- Ethiopian Agriculture Portal

Improved Technologies
and
Resource Management
for Ethiopian Agriculture
Training Manual
Edited by
Mandefro Nigussie
Anteneh Girma
Chimdo Anchala
Abebe Kirub
Ministry of Agriculture and Rural Development
Rural Capacity Building Project
Improved Technologies
and
Resource Management
for Ethiopian Agriculture
Training Manual
©2009 MoARD
Rural Capacity Building Project
P.O. Box 62158, Addis Ababa, Ethiopia
ISBN: 978-99944-53-45-x
Correct citation: Mandefro Nigussie, Anteneh Girma, Chimdo Anchala and Abebe
Kirub (eds.). 2009. Improved technologies and resource management for
Ethiopian Agriculture. A Training Manual. RCBP-MoARD, Addis Ababa,
Ethiopia
ii
ACKNOWLEDGEMENT
Need assessment for short-term training was conducted at
various (federal, regional, zonal, Wereda and Kebele/FTC)
levels of the extension system, with the financial support of
the World Bank, and RCBP would like to thank the Bank for
the critical need assessment conducted.
The assessment report was reviewed and clustered, which
was then converted into modules with the technical support
of the World Bank, CIDA and MoARD. The project would
like to thank those who contributed in the review processes.
The overall support of MoARD, EIAR, Haramaya University,
Melkasa Research Center and Holetta ATVET College are
highly appreciated. All trainers (scientists, lecturers or
experts) provided theoretical and practical training of high
quality that enabled trainees to significantly up-grade their
knowledge, skill and attitude in their respective areas of
specializations.
The contribution of federal and regional RCBP staff was
quite immense, and that is highly appreciated. Thank you
all for the wonderful job done!
Mandefro Nigussie
RCBP Coordinator
iii
Principal Contributors (alphabetical order)
Dr. Abate Bekele, Farm Management
Mr. Asmare Dagnew, Fruits
Mr. Dechasa Jiru, Farm Forestry
Dr. Erenso Degu, Sorghum
Dr. Firdissa Eticha, Wheat
Mr. Fitsum Alemayehu, Soybean
Mr. Adugna Wakijira, Oil Crops
Dr. Kindu Mekonnen, Watershed Management
Dr. Lemma Desalegn, Vegetables
Mr. Lijalem Korbu, Chickpea and Lentil
Dr. Mosisa Worku, Maize
Mr. Mussa Jarso, Highland Pulses
Dr. Setegne Gebeyehu, Haricot bean
Dr. Tilahun Seyoum, Post harvest
Dr. Tilahun Hordofa, Irrigation
Mr. Yohannes Gojam, Dairy Management
Organizers(alphabetical order)
Mr.
Mr.
Mr.
Mr.
Anteneh Girma
Chimdo Anchala
Moges Hiluf
Worku Fida
Facilitators
Mrs. Abebayehu Fekade
Mrs. Yodit Mezmur
Mr. Atkilt Gifom
Mr. Gebremichael Demissie
iv
Contents
Acknowledgement
Principal Contributors
Preface
1.
iii
iv
vi
FARM MANAGEMENT
2
2. IMPROVED CROP PRODUCTION
2.1. Cereals
2.2. Pulses
2.3. Oil crops
2.4. Vegetables
2.5. Fruits
26
26
41
79
93
123
3. POSTHARVEST MANAGEMENT
3.1. Postharvest Technology of Cereals and Pulses
3.2. Postharvest Technology of Green Coffee and Spices
3.3. Postharvest Handling Fresh Fruits and Vegetables
3.4. Fruit and Vegetable Processing
3.5. Milk Processing
3.6. Meat Processing
3.7. Food Hygiene and Environmental Sanitation
132
138
173
189
219
230
233
234
4. NATURAL RESOURCE MANAGEMENT
4.1. Agro-forestry
4.2. Irrigation water management
4.3. Watershed management
252
252
273
289
5. DAIRY MANAGEMENT
297
v
Preface
Rural Capacity Building Project (RCBP) is (one of the projects financed
by the World Bank and CIDA) being implemented by Ministry of
Agriculture and Rural Development (MoARD) with the objectives of
improving agricultural services and systems. RCBP intervention is
focusing on human, physical and system capacity improvement of the
agricultural education, research, development and marketing. The
human resource development include long-term, short-term and
experience sharing visits. Over 1200 professionals are undertaking longterm training (BSc, MSc, PhD levels) within and outside the country in
various fields of specialization. The short-term trainings organized by
RCBP are of two types: modular and other innovative skills which are
being conducted nationwide and region specific, respectively. The
modular training is unique in that critical gap analysis was conducted
and the assessment results were clustered into nine modules (Practical
extension methods and approaches; participatory skills and methods
including PRA; participatory program planning, reporting, M&E;
PTD/PID approaches; communication, facilitation and networking
skills; report writing and documentation of farmer best practices; post
harvest management, integrated farm management and improved farm
practices, marketing and small-scale agribusiness development).
The nine modular trainings were advertized and 11 institutions
submitted their interest, of which four well qualified institutions (two
consultant firms, one NGO and a local University) were selected to train
the nine different modules. Accordingly, Haramaya University
conducted three modular trainings (Practical extension methods and
approaches, post harvest management and marketing and small-scale
agribusiness development), Dynamic Development Studies and Capacity
Building Consults conducted two modules (Participatory Program
planning,
facilitation
and
communication
skill)
WABEKBON
Consultants PLC conducted one module (participatory rural appraisal
(PRA) and Agri-service Ethiopia did two modular trainings (PTD/PID
approaches, report writing and documentation of farmer best practices).
The training materials were provided to individual trainees for the
specific module they attended. However, all trainees need all the
training materials for their future use. Therefore, compiling the different
modules into one or two volumes is of high priority knowledge
management. RCBP compiled the nine modules into two volumes (Vol-I
dealing with integrated farm management, agricultural technologies
related with crops, livestock, natural resource and post-harvest
managements, and Vol-II consisting of marketing and agri-business
development and all other soft skills: extension methods, knowledge
management, facilitation and communication skills, M&E, PTD/PID and
PRA).
vi
These two volumes of the training manuals are consider most relevant
and useful in enhancing roles and responsibilities of the subject matter
specialist (SMS) and development agents (DAs) assigned at various
levels of government. These compiled training manuals are intended for
SMS and DAs who have at least a little background in basic agricultural
knowledge; but seek to learn advanced ideas and their application in a
variety of practical situations.
The core materials of this manual (Volume one) are results of scientists
who are working in the National Agricultural Research System), while
Volume II materials are from senior experts working in key consultancy
firms. Each module had intensive practical sessions of over 60%.
However, RCBP cannot tell whether the trainees have the desired level of
understanding to take-home or not. Here, these manuals have
significant role to play as a backup to do the next step training either in
their working area or outside. The manual can also be used for
professionals working in higher learning and research institutions, state
farms, private farms, cooperatives, planning and monitoring as well as
for individual farmer. In general, the manuals will provide the important
tools needed.
In summary, the two volumes of the RCBP modular training manuals
provide important tools needed to be an effective and efficient
agricultural expert to enhance the agricultural development effort of
Ethiopia
Abera Deresa, PhD
State Minister
MOARD
vii
1. Farm Management
F
ARM MANAGEMENT becomes more important as it involves the full range of local resources,
human and material to resolve identified concerns. Thus, in the context of farm management,
there are three crucial elements to be considered:
•
•
•
All rural people and many of the economic, social, political and cultural activities which are relevant to
their well-being, are by definition located in isolated buildings or in settlements that are both small and
widely separated;
The wide stretch of land that necessarily separates rural communities is subject to a mass of powerful and
competing demands and pressures as agriculture and other forms of land-extensive economic activity are
compelled to restructure; and
In a variety of ways and for a variety of reasons, an increasingly expanding and ‘space hungry’ urban
population creeping or slipping to both those small settlements and to the wide stretch of land that separate
the rural people.
Having stated the above reality as an introductory remark, let us now explain farm management in
order to have a precise understanding. Actually, one has to coin first the words “Farm Management”
separately.
What is farm?
A farm is the area cultivated by a farmer or a group of farmers managed in common. Legally, a farm
means an area of land devoted to agriculture to raising crops or a few heads of livestock. A farm is a
socio-economic unit where a farmer drives his food and cash income for the whole family. Farm is
also a source of happiness to the farmer and to his family, and it is a decision-making unit where a
farmer has many alternative uses of the resources to raise crop and livestock products at his own
disposal. The economic prosperity of a farm largely depends on the viability of the farm and on the
use of farm inputs and managerial ability. Today, in most of the advanced countries, people are
prosperous because farmers are well organized to produce enough for the rest of the society due to:
•
•
•
better allocation of resource among various uses;
adoption of improved technologies and innovations; and
viable farm size.
Farmers operate their farms on profit footing through increased production per unit of cultivated area.
What is management?
Management is a science applied to organize a firm for securing the greatest continuous profit. It is
also the art applied to increase agricultural production per unit of area or unit of cost to meet
population demand in food. As an art, it can be traced to the prehistoric period when the primitive
man began to domesticate animals and raise crops. It has been developed based on knowledge and
experience of many individuals for thousands of years and handed over from father to son in an
unbroken succession all over the world. Countries of oldest civilization like china, India, Greek and
Italy acquired considerable skills in the art of farm management in a period when most of the
countries were in a hunting stage. The foot-prints of the art are reflected in the method of cultivation,
manner of raising livestock and the physical appearance of farms at the various stages of
development.
1
What is farm management?
Farm management is described as a science of decision-making applying economic principles and
technology to production to maximize a set of goals based of relevant sociological, psychological, and
philosophical considerations. Farm management is a branch of agricultural economics, which deals
with wealth-spending and wealth-earning activities with the idea to secure the maximum possible net
income consistent with the conservation or maintenance of environmental capitals. Thus, success in
farm management calls for enrich experience with soil fertility, climatic conditions, farm equipment,
diseases, insect-pests, animal raising and marketing affairs. A person who has little knowledge of
agricultural practices can be neither a successful farmer nor a good businessperson though s/he may
have acquired knowledge through book studies and farm records. Without being in touch with the
various agricultural operations, her/his efforts and investigations have little practical value. It is one
the thing to read about management of a farm but quite another thing to execute it or put it in practice.
The knowledge and skill required for proper management of a farm is gained with considerable
education and experience. Experience ripens the judgment that enables the farmers to utilize land,
labor, and capital to the best economic advantages.
Success in farm business depends on:
•
•
•
•
•
background knowledge of the principles of crop production and livestock raising through practical
acquaintance;
good knowledge of the business principles of farm management;
good managerial capacity of the farmer;
ability to learn by doing, using and interacting; and
ability to focus on actions.
With the adoption of modern technology in farming, the farmers are increasingly concerned with the
choice and decision-making in the pursuit of maximum net profit per hectare. As resources become
scarce, farmers must adopt innovation and require knowing the technical efficiency of inputs and the
price ratios of the input-output. To make the farmers willing and able to bring about the desired
changes in the direction of increased production and higher net returns, extension worker could
confidently provide farmers with the following:
•
•
•
•
•
Proper recommendations on the new practices;
Reliable information concerning the underlying input-output and price relationships so those farmers may
modify the recommendations to suit their specific conditions;
Correct guidance how to weigh technical efficiency for the execution of a successful farming programs;
Help famers how to conduct strengths, weaknesses, opportunities and threats (SWOT ) analysis;
Teach farmers how to bring sustainable development which appears in four forms:
•
•
•
•
Environmental capital, which comprises stocks and flows of energy and matter, and the physical states, such
as climatic conditions or ecosystems, to which they give rise to production and productivity;
Human capital, which comprises the ability of individuals to do productive work, whether paid or unpaid,
and this includes their physical and mental health, strength (stamina or endurance), knowledge, skills,
motivation and attitudes;
Social capital, which relates not to individuals but to the social structures, institutions and shared values
which enable them to maintain and develop their human capital and to be productive. It therefore embraces
firms, trade unions, families, communities, informal friendship networks, voluntary organizations, legal and
political systems, educational institutions, health services, financial institutions, systems of property rights
etc.; and
Manufactured capital, which comprises material goods such as tools, machines, buildings and infrastructure,
all of which contribute to the production process without becoming embodied in its output.
Farm management as a science of decision-making on the use of scarce resources helps farmers to
realize production goals on a continuous basis. Production goals are:
•
•
Maximum net return and satisfaction;
Better standard of living; and
2
•
Consolidated community-run business to secure employment.
The promotion of community and community involvement has become a major feature of farm
management programs for the following reasons:
•
•
•
•
Community’ is valued as a consumer good with a lot of people belonging to be a real community;
Community is valued as a resource striving to enhance and exploit the available resources;
The rural community is a collection of people well integrated into their local society and their environment
and living productive and rewarding lives; and
Community is seen as the essence of good life though it is difficult to identify and promote for various
reasons.
Scope of farm management
Farm management falls in the field of microeconomics. It deals with the allocation of resources at the
level of individual farm. Farm management covers all aspects of farm business, which has a bearing
on the economic efficiency of production resources. The types of enterprises to be combined, the kind
of crops and varieties to be grown, the dosage of fertilizer to be applied, the implements to be used,
the way the farm functions fall within the subject of farm management. Thus, to carry out modern
agriculture successfully, knowledge of farm management is useful in three areas:
Farm management research
Year after year new implements are manufactured, new input substitutes are coming in the markets
and better doing practices are formulated to satisfy the increasing desire of cultivators for more
income. Because of all these changes, farm management research must be continuously strengthened.
Although the problems and solutions vary from time to time and place to place, the following aspects
need to be continuously studied:
•
•
•
•
•
•
•
Delineation of homogeneous type of farming areas;
Generation of input-output coefficients;
Formulation of standard farm plans and optimum cropping patterns;
Developing suitable models of mechanization;
Determination of farm size based on productivity;
Determination of production costs; and
Evaluation of agricultural policies on farm development and growth
Farm management teaching
Training in farm management is essential to understand farmers’ responses to policies and
technological breakthroughs. To help the farmers take the right decisions as to what to grow, how
much to grow, how to grow, when and where to sell and buy, continuous training in farm
management has become necessary.
Farm management extension
Once the results of a study are known, they must be made available to the farmers. They have to be
educated and trained in the application and adoption of the research results. Many farmers in the
developing countries do not have the required education to implement the research results. Thus,
findings of farm management research have to be demonstrated to convince the farmers. The
managerial ability of the farmers can be improved through district, block, and village level training
camps, demonstration farms, and farmers’ training centers (FTCs). Research, teaching, and extension
together seek improving the ability of farmers to introduce desirable changes in the utilization of
scarce resources of the farm with a view to increase income to improve living standards and
satisfaction.
3
Nature and characteristics of farm management
Farm management science has many distinguishing characteristics from other field of agricultural
sciences. A few of the important characteristics are:
Practical science
Farm management aims at testing the applicability of research findings by demonstrating on a given
farm situation. It helps the farmers to select a method, which is practicable and economical to their
particular situation taking into consideration the volume of work and financial implications.
Profit-oriented
Farm management science alone is interested in the profitability of the farm along with practicality of
an idea. For instance, scientists such as agronomists and plant breeders concern themselves with
obtaining the maximum yield per hectare irrespective of the profitability and the cost of input incurred
but the farm management specialist always considers the costs involved in producing each unit of the
output in relation to the returns and decides the optimum level input combination. The relevant factors
to be considered in farm management are:
•
•
•
•
•
Financial implications;
Market outlets;
Transportation facilities;
Storage facilities; and
Costs of production.
In brief, other sciences concern with the physical efficiency of production resources whereas farm
management science concerns with physical, economic and allocation efficiencies as the major
criteria of selection or adoption of improved practices. Nowadays, sustainable use of resources is also
one of the tasks of farm management science.
Integrating science
Farm management is an integrating science in a sense that the facts and findings of other sciences are
coordinated for the solution of various problems of individual farmers with the view to achieving
certain desired goals. It considers the findings of other sciences in reaching its conclusions and
deciding usefulness of new inputs under specific set of conditions.
•
•
•
•
Optimum combination of practices;
Constraints of individual farms;
Evaluation of farm results (quality, cost, volume); and
Benefit-cost ratio.
Broader field
Farm management decisions are made by getting reliable information from more than one discipline.
Most of the physical and biological sciences concern themselves within limited or narrower
compartments of information. Farm management specialist and economist are expected to know the
broad principles of all other concerned sciences in addition to business principles of farm
management and economics. Better decision-making and best choice of alternatives of farming
practices should be based on:
•
•
•
•
•
•
knowledge sources from other sciences;
wider compartments of information;
good managerial ability;
holistic in approach;
emphasis on integration;
local partnership approach;
4
•
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bottom-up approach; and
area-based approach
Micro Approach
Farm management is a micro-approach where it treats every farm unit unique in terms of resources,
potentials, and problems. It recognizes that no two farms are identical with respect to soil, climate,
farmers’ managerial abilities, and other production resources. Each farm unit has to be, therefore,
treated or studied individually. The major emphasis of micro-approach lies on treating the farm as an
operation unit to tailor recommendations to fit into the resource position of the unique farm studied.
When doing SWOT analysis on the micro-approach, it is necessary to target at the following issues:
•
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•
•
•
•
•
•
•
•
•
•
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An adequate income;
Employment;
Affordable and adequate housing
Education and training;
Information advice;
Easy access to services and facilities;
Social integration;
Develop the power to influence events (the community and others should be the subject of their lives not
the object of their lives);
Community empowerment- placing more power in local hands, empowering individuals and communities
to take control of their situations;
Increase mutual care at local levels;
Develop a share or sense of belongingness to the local place;
Enhancing the skill and capacity of the local community;
Encourage interaction of local communities;
Consider both vertical and horizontal relationship; and
Develop complementary and supplementary enterprise.
Treating farm unit as a whole
In farm management context, a farm as a whole is considered the unit for decision-making because
the objective is to maximize the returns from the whole farm instead of only improving the returns
from a particular enterprise or practice. Farm management is much more concerned with the
productivity of all crops instead of the productivity of one crop. Highest return of a particular crop per
hectare may lead to less income earning of other enterprises because the farmers may be allocating
most of her/his resources to one crop or one plot of land instead of using each unit of labor and other
resources where it adds to the greatest returns. This is true where many of the farm resources are
limited and where there is free movement of commodity between rural and urban centers. Thus,
applying the principles of farm management aims at reaching the optimum enterprise mix so that the
farmer should obtain the highest income from his total farm organization.
Relationship of farm management with other sciences
Farm management is dependent on many other sciences such as:
Economic theories
The tools and techniques for farm management are supplied by the general economic theories. The
law of equi-marginal returns, the law of variable proportions, the principles of input substitutions and
the marginal analysis are all tools of economic theories used in the farm management analysis.
The economic theories that play an important part in farm management analysis are:
•
•
•
agricultural finance;
credit and co-operative marketing; and
land economics.
5
Other social sciences
Farm management has close relationship with other social sciences like anthropology, psychology,
and sociology. Psychology provides information on human motivations and attitudes. In decisionmaking, many psychological aspects and mental reservations of decision-maker come in picture such
as attitudes towards taking risks and work under conditions of uncertainty. Rural sociology deals with
the social problems, responses, and reaction of rural people and has a great bearing on farm
management decision-making of the farmers.
Political science
The acceptance of new production techniques and methods in farming involves political aspects of
farm management. The legislation and political actions of government affect the production decision
of farmers
•
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•
•
•
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price of output and input;
Scale of production;
Land utilization policy (land size, floor and ceiling on land);
Restrictions imposed on the growing of certain crops;
Encouragements on the growing of certain crops; and
Inward (food self-sufficiency) and outward production (export-orientation) strategy.
Supporting sciences
Statistics and mathematics are other sciences that have been used effectively and extensively by the
farm management specialists and agricultural economists. These sciences are helpful in providing
methods and procedures to analyze and evaluate data collected from different sources. Specific farm
problems will be solved through the application of supporting sciences.
Physical and biological sciences
Farm management heavily depends on other physical and biological sciences for its source material.
Farm management science defines the optimum use of resources within the framework of resource
constraints whereas physical and biological sciences specify the production possibility without
relating with the cost incurred. Various sciences, thus, contribute to the solution of economic
problems of farms. It is, however, the main task of farm management specialist and agricultural
economist to determine how and to what extent the findings of other science should be used. This is
by no means an easy task for farm management specialist and the economist. Moreover, knowledge of
farm management and agricultural economics is necessary to different types of agricultural specialists
and to those who are working in the rural development. Hence, let us discuss briefly the relationships
between farm management and agricultural economics with different types of agricultural specialists. Farm management and plant breeder
Plant breeder should have some knowledge of farm management or agricultural economics to find the
desirable plant variety that possesses economic characters such as:
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•
•
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high yielding variety/unit area and unit cost;
suitable for profitable cultivation in a particular area;
compatible to the socio-economic set ups; and
variety of less risk and uncertainty.
Farm management and animal breeder
Animal breeder should try to find out a breed of dairy cow and fattening livestock that can give
•
•
maximum returns/unit feed consumed;
maximum returns/human energy and cost incurred;
6
•
•
compatible to the socio-economic and environmental conditions; and
breed of less risk and uncertainty.
Farm management and agronomist
Agronomist should be able to find out a better method of agronomic practices that gives maximum
profit.
Farm management and entomologist/pathologist
Entomologist or pathologist has to find out desirable crop protection measures that can maximize
production and minimum risk.
Farm management and agricultural engineer
New tools or implements, which the engineer invents, should be economically affordable, technically
simple and socially acceptible
Farm management and chemist
Agricultural chemist should be able to find out fertilizer that is economical one. He should also
suggest the economical method of fertilizer application. These are logical reasons why different
agricultural experts must know some concepts of farm management and agricultural economics. In
order to make a precise demarcation between agricultural economics and farm management, let us be
familiar with the branches of agricultural economics, which is conveniently divided into the following
components:
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•
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Agricultural finance;
Agricultural co-operation;
Agricultural marketing; and
Farm management and production economics
Specific objectives of farm management
Farm management is a rational allocation of land, capital, and labor that are relatively scarce to
achieve a set of goals and objectives. What are these set of goals and objectives that could be met by
modern producers?
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To produce enough agricultural produces to feed the existing and increasing population, import substitution,
export promotion, and creating some reserves;
To provide reliable information that assists farmers in their farm management so that they are better to
achieve their goals; and
To provide policy makers with reliable information on farmers and their management to formulate better
government policies and development plans.
However, to meet these specific objectives, farms should make great and durable efforts in all
production sectors. In developing counties, some of the remedies/solutions to farm problems in
developing countries are:
•
•
•
•
small-scale farmers as a major rural development have to be promoted and restructured;
ability to transfer technologies to successful application should be strengthened;
expected to test agriculture economic principles to apply despite the historical context;
expected to have the means to see things thoroughly and methodically; and
7
•
expected to have well-developed educational systems to place the necessary foundations for development at
all levels of production.
Problems of farm management
Farm management problems vary from place to place depending largely upon the degree of
agricultural development and the availability of resources. Some of the most common problems in the
field of farm management and planning are:
•
The size of land holding: fragmented landholding and unfavorable man-land ratio lead to poor financial
position and limit the scope of farm business expansion. Farms need to have reasonable landholding to
produce enough for family at all times and sale for the market so that they could afford to buy modern
inputs and processed/manufactured goods for use.
•
Farm as household: The work habits of a farming population are closely associated with family food
intake, living conditions, sanitation and purchasing power. This make difficult to draw line of demarcation
between farm and household. As a result, farm is seen as life-stay business without introducing innovations
and better ways of doing.
•
Capital inadequacy: Capital (fixed and working) is a serious deficiency in small farm development
because of limited marketable surpluses. The new technologies (improved seeds, fertilizers, plant protection
chemicals, machinery and irrigation) demand heavy investments. However, the small-sacle farmers, in
developing countries, cannot meet these investments from their own financial sources.
The most pressing needs to keep farms on a growth path are:
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low cost technology;
adequate and timely credit;
saving and investment habit of farming population;
development of community-run businesses;
adding values to local products ad resources; and
increased input productivity.
Unemployment and underemployment
This problem, in agriculture, results from the following:
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•
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Farm landholding;
Large family labor supply
Seasonal nature of production; and
Lack of support to develop rural industries; and
Lack of accessibilities.
Underemployment or unemployment brings laziness, social tension, and frustration. It also reduces
efficiency and productivity of rural labor.
Slow adoption of innovation
Small farmers usually conservative and sometimes skeptical of doing new practices because of the
fact that established attitudes and values do not change overnight. The rate of innovation adoption
largely depends on the farmers’ willingness and ability to use the new information, and the capacity of
research and extension programs to bring the finding across farmers so that they can commercially
exploit the research findings.
Inadequacy of input supplies
Farmers are willing to introduce new changes to their farms but they still face difficulty in obtaining
the required quantity and quality on time to sustain the changes. The main reasons are:
8
•
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Shortage of foreign exchange;
Lack of raw materials;
Lack of skill and capital for domestic industries;
Lack of infrastructure; and
Lack of communication and reliable markets
Managerial ability
The most important pressing problems for many years to come will be to improve the managerial skill
of the large number of small farmers, extension agents, and researchers in developing countries. This
is necessary to make the attitudes of farmers, extension agents, and researchers responsive to
technological changes. Educating farmers about innovation on a mass scale is thus the most important
need. Even illiterate people can be educated through demonstration or the application of new
techniques and better ways of using the inputs available. Sustainable investments need to be made on
human resource development to improve managerial skills. Social and human capitals are considered
as casualties of both inappropriate and appropriate rural development. It is the active element of
production and mechanism of order.
Natural resource management
In developing countries, the knowledge on the significance and contribution of the basic natural
resources to agricultural development is generally deficient.
•
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Why some countries develop and some others not developed?
Why some farms have greater efficiency while some others have lower efficiency?
What attributes to development variations?
o
o
o
o
o
o
o
o
o
Is it the availability of natural resources?
Is it a question of social and human capital?
Is it a question of investment in technology?
Is it a question of knowledge transfer mechanism?
Is it a question of education gap between generations?
Is it a question of a coherent and integrated theory of growth model?
Is it a question of deliberate and conscious choice of the management?
Is it a question of stability in policy?
Is it a question of implementation capacity?
Two basic natural resources contribute most to farm development are:
Land
Among the natural resources, land is a mother of production where all other means of production are
connected with it. Agricultural development is possible in three different ways that are not mutually
exclusive:
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Bringing more land under cultivation;
Increasing productivity per unit of area; and
Increasing production through area and productivity interaction.
The first alternative is possible without changing traditional farming methods whereas the second is
entirely dependent on applying improved farming technologies. Traditional agriculture can produce
an acceptable level of agricultural products as long as the population pressure on the land is not
excessive. However, when the growth of population overtakes or exceeds the expanding land use, the
ability of traditional agricultural to produce even at a subsistence level decreases and a state of
continuous deterioration sets in the process of land use:
•
•
•
Decline of soil fertility due to population pressure and overgrazing;
Destruction of soil cover by erosion; and
Inability to re-establish natural plant cover.
9
In fact, economic development in agriculture depends on the proper use and conservation of the soil.
Population pressure, destructive tillage methods, faulty irrigation practices, and overgrazing lead to
deterioration of the soil and this is frequently an irreversible process. Erosion is a natural process
contributing to soil formulation by wearing down mountains and building up the soil in more level
lands. Proceeding at a slow pace may be very beneficial. However, it becomes a catastrophic process
when it is excessively accelerated by population pressure and overgrazing. The main factors of
accelerated erosion are:
•
•
•
•
Ploughing farmland up and down in marginal areas and semi-arid regions which is generally conducive to
violent rainfall and wind erosion;
The destruction of vegetative cover of the slopes in the humid regions, leading mainly to water erosion;
Incorrect tillage practices inherited through successive generations; and
Erosion caused due to excessive overgrazing.
It is possible to bring the potential land under cultivation but capital costs of developing new lands are
generally high and social and cultural problems can also prove to be serious obstacles in developing
countries. Land in agriculture is the active means of production that has some certain peculiarities as
compared to other means of production. These peculiarities are:
•
•
•
•
•
land serves a means and object of labor;
land exists on space and is a free gift of nature;
it cannot freely reproduced or multiplied as other means of production;
under proper management, land does not depreciate; and
whatever land gets, it gives back in terms of output.
However, lack of knowledge on land and uncontrolled population increase lead to the breakdown of
the ecosystems and loss of land cover, which constitute a grave threat to our survival. The gravity of
the situation in developing countries makes it imperative to adopt measures immediately to prevent a
further deterioration of our natural resources before it becomes too late. Water resources
The second largest areas of unused and potentially arable land amounting to about 750 million
hectares are found in the dry regions. Their cultivation is dependent on the possibility of developing
irrigation schemes. The increase in water requirements must be far more considerable in the dry
regions than the humid region, for two main reasons:
•
•
Water is the limiting resource in the dry regions and determines the extent to which other resources can be
developed; and
An increase in water requirements is concomitant with the rise in the living standard of the society.
The existing shortage of water supply in the dry regions does not necessary imply a lack of water
resources. In many of the dry regions, there are potential water resources that could be developed with
the necessary knowledge and investment. Additional water for agricultural production and human
consumption can be made available by:
•
•
•
•
improving water conservation methods;
increasing the efficient use of existing water resources;
allocating water among competing demands; and
developing unconventional water supplies. Irrigated agriculture
The use of low-cost and water-saving irrigation technology by small-scale farmers in developing
countries could increase yields of most crops by 100 to 400 percent. Despite this, some of the world’s
most needy farmers are still unable to use water to irrigate their land effectively because farmers need
for on-farm irrigation technologies, construction, and management of micro-dams and river
diversions. Thus, to bring small-scale irrigation to African farmers, it requires to develop irrigation
10
capacity that needs involvements of different actors working on agriculture and rural development.. In
many countries, water scarcity is a critical constraint to food production and a major cause of poverty
and hunger. Unlike other developing countries, Ethiopia has large bodies of water and potential
irrigable land of about 10 million hectares. At present, the country uses only 6% of the potential
irrigable land. Different methods of water harvesting may provide a viable solution for dry regions in
which no other source of water is available. Conventional irrigation can be a powerful tool for
agricultural development, not only in the dry regions, but even where rain-fed cropping is possible.
The development of irrigation can also have an impact on the development of non-agricultural sectors
of the economy. Irrigation agriculture can be the most productive form of farming in developing
countries. However, disappointing results have been obtained in a large number of irrigation projects
because of fundamental errors in planning and implementation. The advantages of small-scale
irrigation projects in which water resources are developed at the level of the individual farm or village
are being increasingly appreciated. Their cost per hectare is reasonably high than rain-fed even though
the greater proportion of the work can be carried out by the beneficiaries and allocation of water is
easier. Principal water resources
Irrigation water may be drawn from different sources. The principal water sources are:
•
•
•
•
•
•
natural rivers and streams;
water reservoirs which make it possible to regulate the flow of streams;
underground water by means of wells;
unconventional sources such as the use of effluents from sewage treatment;
precipitation; and
water desalination.
However, many development irrigation schemes have failed partially or entirely because of lack of
information on the natural resources that are available to the area to be developed for agricultural
production. All available estimates suggest that the developing countries, overall, have not used even
half of their potential land and water resources. This underutilization is generally due to limitation
imposed by the following:
•
•
•
•
Primitive technologies available in the countries;
Environmental constraints;
Capital costs of developing irrigation system is generally expensive compared to rain-fed agriculture; and
Social and cultural problems.
Thus, the annual increase in food supply at the rate required can only come from two factors
1. Increased cultivated area and increased use of more water;
2. Increased productivity of land and water resources; and
3. Increase in production because of interaction.
Desert areas have traditionally been used for extensive grazing by livestock. Without irrigation, the
areas may be utilized best, if improved ranching methods are adapted. The outlook for domestication
of plants adapted to desert conditions is bleak. Agricultural development depends, on the proper use
and conservation of the land and water resources. Farm Decision Making Procedures
Producer must often make decisions on certain fundamental questions regarding crop and livestock
production and farm businesses. Farm decisions are concerned with the land resources, what to
produce, how to produce and how much to produce? Producers must also decide the scale of their
11
farming operations and equip their farm businesses accordingly. Such decisions can be categorized
into the following two groups:
Strategic management decisions
These are the management decisions, which involve heavy investment and have long lasting effect. A
few example of strategic management decisions are on:
•
•
•
•
the best farm size;
the use of labor and machinery uses;
the construction of buildings; and
irrigation, conservation and reclamation programs.
Operational management decisions
Such decisions are continuously made in the day-to-day operation of the farm businesses. The
investment involved is relatively small and impact is short-lived. The frequency of decisions is also
more as compared to strategic management. Farm decisions mainly dealing with: What to produce
In view of technical feasibility, there can be many alternative enterprises available to a particular
farm. Certain enterprises will yield high production returns per unit area or investment as compared to
other enterprise because of favorable climate, soil, and topographical conditions. The law of
comparative advantage will help decide the crops to be grown or the livestock to be raised.
Some of the issues that determine what to produce include:
•
•
•
•
•
•
•
Natural conditions;
Large surplus of benefits over the cost incurred;
Population demand and purchasing power;
Marketing opportunities and transportation facilities;
The right combination of crops and livestock;
Availability of workforces; and
Material resource supplies and availability.
How to produce
There are many substitutable practices and resources to produce a unit product of crop and livestock.
Decisions are made on the best choice or combination of practices. The question of choice among
different alternatives must be based on the following issues:
•
•
•
•
•
•
Choosing the least cost/efficient methods or practices;
The cheapest technological units in terms of efficiency;
The availability of spare parts or service for the technology/product selected;
Farm size and crop grown in the area;
The topography of the land; and
The technical recommendations and advice of experts. How much to produce
The question of how much to produce deals with two basic concepts
Product-mix
It involves degree of specialization and diversification. Combination of crop and livestock enterprise
will depend on the level of resource available and land use capabilities. Product mix may have either a
complementary or a supplementary relationship. Based on the scarcity of resource, one or two
12
enterprises will be selected. One should not put all the acreage under one crop based on its individual
profitability because one or the other resources will become a limiting factor if production of that crop
is expanded beyond a certain limit. The factors influencing the product-mix are:
•
•
•
•
•
•
labor availability;
land availability and use;
use of by-products;
distribution of income;
maintenance of soil fertility; and
minimization of risk and uncertainty
Level of resource use
The amount of resource that should be allocated for each crop and livestock is the second dimension
of the problem. Different levels of inputs will yield different levels of output. A management problem
to decided on the combination and level of input use based on the overall goals of the farmer to
maximize the return or profit; and minimization of costs and losses. At national level, the question of
how much to produce can be determined by how much a crop should be produced to feed the existing
and increasing population in the country. Thus, the total quantity is related to the total cultivated or
cultivable land and the yield level obtained per unit area. At farm level, the question of how much to
produce is determined by increasing farm input until the extra benefit no longer exceeds extra cost.
The right combination of inputs should be practiced in order to reach the climax point. On the other
hand, the highest combination of resources until the maximum output is being obtained tells how
much to produce at farm levels. This is often difficult to determine at farm level without having the
necessary knowledge and conducting research trails. When to produce
Farmers take care of the time while they decide what, how much, and how to produce. Farmers are
often confused whether to produce normal, early, or late varieties of crops, or what combination to use
to get the best price during different periods.
What to produce, how much to produce, how to produce and when to produce should be decided by:
•
•
•
Traditional methods: including experience of ancestors, primitive cultures, expertise recommendations,
and suggestions.
The technical method: This method considers the soil types, vegetation, local climate, crops grow,
livestock to rare, resources available, population density of forage crops, range management, etc.
Economic method: it is a method where we usually obtain the possible yield per unit area under
minimum inputs. The concepts is closely linked with:
o
o
o
o
additional yield obtained per additional cost incurred;
relative selling prices of the output over the production cost
size of benefit and cost incurred; and
total income earned per household.
The traditional, economic, and technical solutions may not be the right track to draw a precise solution. It is
necessary to conduct a mass of experiments and demonstration trials at farm level mainly to find out the
minimum variant of expense as to obtain the maximum return and to study the percent structure of input-costs
on both crop and livestock production. However, the best proportions of inputs are not the best all the time
because of change in:
•
•
•
•
economic conditions;
methods of production;
the relative price of input and output; and
the real situations.
Thus, the economic, technical, and traditional solutions should be fully supported by research
investigations (findings and evidences).
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Practices of Farm Management
Having examined the overall outstretching issues of farm management, we now continue with four
themes devoted to the practicalities of preparing and executing strategies to achieve farm
development. The issues we consider to discuss are the stages of farm diagnosis, planning,
implementation, and evaluation.
Diagnosis: Researching the Baseline
Introduction
Diagnosis is the practicality and feasibility of preparing and executing strategies to achieve objectives
of farm management. The stages of diagnosis, planning, implementation, and evaluation are all interrelated in the process of realizing farm management objectives.
Definitions and importance
Logically, diagnosis is the first step in the process of farm management task. It is the task of
establishing the baseline conditions of a farm or an area prior to creating a development program for
it. This baseline study has to include reference to resources, opportunities, problems, needs,
constraints and the relationships between them. Another term for diagnosis is baseline study. The
importance of diagnosis has been underlined by a number of farm management experts. Area in
question should be based on an assessment of social and economic trends and conditions and the
needs and opportunities to which they give rise to increase farm productivity. There should be an
assessment of the resources likely to be available. Diagnosis of a particular farm or area focuses on
the following questions:
•
•
What are the most serious problems in the farm or in the area? and
What are the greatest needs in the farm or in the area where we should capitalize for any particularly
disadvantaged groups?
Once we identified the problems of farms, it is necessary involve the various local partners in the
implementation because local people are source material of the diagnosis to get initial momentum. For
all cases, technical assistance should be given to new and inexperienced local action groups so that
they could undertake appropriate preparatory work, which includes analyzing the needs, wishes and
the preparation of a strategy and business plan. To this end, a technical paper suggesting how best to
plan and execute a diagnosis of the area and distilling good practice from recent experience produced
by local and an international team should be considered. Identifying problems at farm or local level is
insufficient or even in some respect inappropriate. In fact, a locally focused farm management
program could be usefully explored and clarified but it should be linked with external market
opportunities, institutions, networks, and various kinds of trans-national collaboration. Farm
management introduced in great haste reflects a measure of disappointment with the quality of earlier
baseline studies and reveals many cases where the initial survey of needs and resources is withheld
and non-existent. Diagnosis in farm management should give more emphasis on comprehensive
resource audits and detailed analyses of strengths, weaknesses, opportunities and threats, prioritization
and the identification of people with leadership and management skills.
Key issues
The first issue is whether the diagnosis should be reserved for an expert team, working largely from
statistical and other documentary evidences of the area, and some interviews with key players or
whether a substantial effort should be made to get local people to articulate their opinions and, indeed,
to serve as witnesses of the local scene. Frequently, local partnerships or development agencies need
to be persuaded that a more participatory approach is beneficial. It also promises greater legitimacy
for the whole development program. Indeed, a diagnosis with a strong participatory component can
14
quite properly be seen and justified as a part of the development process including diagnosis,
evaluation, and implementation of farm management objectives. In the local development context,
diagnostic evaluation has various purposes; it can also be carried out at various levels and at various
times. As far as levels are concerned, evaluation can focus on a national or international program. The
scope of useful diagnoses in farm management has two main themes. The first is the good news
comprising the area’s resources, opportunities, and strengths that may best be considered under such
headings as:
•
•
•
•
•
•
Natural resources: including its location vis-à-vis potential markets, environment, climate, soil etc.;
Capital endowment: including its infrastructure, built environment, cultural landscape etc.;
Human resource: including people as individual, their education and skills, leadership capacity etc.;
Social and institutional environment: including the range and vitality of small or big businesses, the
existence of voluntary organizations and the quality of any existing partnerships bringing together agencies
with an interest in local development;
Policy context: including the existing position of relevant agencies concerning the area’s development
potential. Such position could comprise an opportunity, a constraints or a mixture of the two; and
Possible future scenarios: this could provide opportunities to be exploited. A new motorway being
built in the vicinity or the growing popularity of short, market development for farm products, irrigation
expansion to secure food and cash during the off-season are some examples of future scenarios
The second is the bad news that deals with problems, weaknesses, constraints, and threats which
would need either to be carefully sidestepped or else tackled directly so as to reduce their forces. The
categories listed above under the good news are equally relevant here though the task now is to check
for weaknesses to see as it were and in what aspects ‘the bottle is half empty rather than half full’.
Here, bad news is not the expressed problems and needs of the local population and business world. It
is clearly important that any development strategy can and should seek to address good and bad news
together or else ‘put them to one side’. Conclusions
There are tools or approaches that might be employed in carrying out a diagnosis of a farm or an area
prior to formulating and executing farm management programs. Obviously, the best diagnoses will
probably comprise a mixture of the different tools, which are mutually exclusive.
Statistical mapping
This approach, generally, tends to comprise the assembly, analysis, and mapping of farms or small
area statistics from the most recent census and other sources. This method involves mapping at the
commune level across wide rural areas, the incidence of fragility and vulnerability as an indictor of
the local need for development, and of local dynamism as an indictors of the local potential for
sustaining development. A limitation of this approach, when used in isolation, is that it leaves
unresolved a central question, namely whether development initiatives should reflect the need of an
area (geography of need) or that of development potential. Alternatively, to put it more briefly, should
the subsequent development program put the ‘worst first” and channel resource to ‘black spots’.
Resolving this dilemma generally involves a detailed study of farms or an area rather more than is
achieved by the mapping of indicators or indeed by statistical analysis more generally.
The written word
A second approach involves the systematic scrutiny of a whole range of documentary evidence
relating to the locality. However, such evidence is not plentiful in developing countries. Thus, the
challenge is partly to track down what exists and partly to know how to collect what is helpful
evidence. Regarding the latter, one needs to study the resource potential, constraints, popular
concerns, opportunities, threat and to condense the results to the needs of the study. Going back over
the previous years, relevant material will probably scan or scrutinize:
•
Minutes of the meeting of local elected councils and other major voluntary or community bodies;
15
•
•
•
Any planning studies undertaken for the land-use planning authority or the health authority;
Local newspaper concentrating perhaps on the editorial and letters pages; and
Any student dissertations or theses.
It is a method burdened or filled with dangers since the representativeness of the views expressed and
grounding itself is a slippery concept. But used alongside other methods, and particularly used as a
way of drawing up a detailed agenda of local issues for debate. It is, otherwise, a very useful tool and
one, which is easily overlooked by those who mind to undertake yet another survey.
The resource audit
Another approach focuses explicitly on one key element of the situation–the area’s resource
endowment upon which the economic development of the area becomes real.
The six sets of resource are:
•
•
•
•
•
•
Natural environment – the land, forest, water, hills, fauna and flora of the area or the country;
Cultural heritage – the landscape, historic monuments, local architecture, local products and know-how,
local culture, local brands and trade marks of the region of the country;
Infrastructure – the area’s communication nodes, its proximity to urban centers, education and health
facilities, serviced industrial land housing available for rent;
People – their capacity for innovation, leadership qualities, the number of natives of the region in
positions of responsibility, and people with specific qualification and skills;
Organizations – the machinery for inter-communal co-operation, strong voluntary bodies, strong
collective structure such as co-operatives, major companies and the presence of regional labels or brands;
and
Financial resources – the capacity of business for investment, domestic saving, purchasing power, the
fiscal resources of the communes and the local tax base.
In addition to the above, one should ask six questions for an in-depth analysis:
•
•
•
•
•
•
Is there a market capable of exploiting the available resources?
What actual or potential competition from elsewhere exists?
Is existing local machinery capable of exploiting these resources, and under what conditions?
How far are the resources actually being exploited?
How urgent is its exploitation or its conservation? and
Is further evaluative work needed?
Experts’ opinions
Another good practice on baseline studies advocates the creation of local development agency with a
mixture of qualitative personal interviews and group discussion being employed to elicit or draw from
experts list of local issues and the essential information pertaining to the region. Increasing these
leaders’ ownership of the subsequent development strategy is a valuable fact finding approach. This
technique involves well-informed local people and others from outside the area that are well-informed
on some aspects of the local situation or of the forces acting upon it to come together and reflect, not
alone but collectively, on those of four dimensions of strengths, weaknesses, opportunities and threats
of the local situation.
Local testimony
Finally, we must refer to the systematic assembly of evidence and harvesting of opinion from a much
wider sample of the population. Several of such techniques are covered in the community
involvement issues that entail sample survey of the residents of the area under scrutiny. There are
many examples of village appraisal exercises, for example, that can be launched with great
enthusiasm by local activities as a way of establishing local testimony to be fed into a development
planning exercise, only for the whole process to take that the opportunities to influence events is
missed. More realistic, therefore, may be the scrutiny by the research team of the crop of local
appraisals or other social survey recently carried out in the area, with to distilling useful evidence. If
16
such reports do not exist in three or four-month time limit, then the best approach may be to convene
focus groups or something similar involving representative samples of ordinary local people.
Strategic Planning: Orchestrating Action
Introduction
Here, we are concerned with farm strategic planning and its value in farm development. The previous
section considered diagnosis, which provides a necessary point for strategic planning. Strategic farm
planning is a structured process whereby the actors or producers define a long-term vision of farm
management based on identified needs and priorities, and set out clear objectives and a range of
measures to work towards that vision over a defined period. Moreover, it is not the geographical
extent of the farm or the area in question that determines the strategic plan but the degree to which it
stands above the detail—the challenge of farm planning programs across a reasonably extensive area.
Strategic planning seeks to distil answers to three key questions:
•
•
•
What do we want to do?
How are we going to do it? and
How do we know if we are doing it right?
Any strategic farm planning exercise can be judged by the care we devote in seeking answers to those
questions and the clarity with which the subsequent plan expresses the questions set. Surprisingly, an
enormous amount has been written on strategic farm planning since it is relevant to almost any human
endeavor–government business, public service delivery, military action, or whatever. The general
principles of strategic farm planning reflect, perhaps, certain particular characteristics of a farm or
local development when compared with those other endeavors, notably the following:
•
•
•
•
Strategic farm planning is multi-dimensional in scope – social, economic, cultural, environmental and
political – and the need to integrate those concerns and dimensions;
Strategic farm planning involves multiple actors or stakeholders being persons or organizations with a
legitimate interest in the matters considered;
Strategic farm planning need to treat the planning process as an exercise in involvement and capacity
building – in other words to see the process as itself one of the engines of development; and
Strategic farm planning ensues or results in genuine/real development and not the delivery of certain goods
or services.
Strategic farm planning is considered as practices in pursuit of local rural development. Generally, the
assumption will be that a development agency or local partnership at the area-wide level is
undertaking this task but, increasingly, strategic planning for local development is being attempted by
an ad hoc committee, groups working at the level of the individual village, rural community or small
town. Indeed, the second case study in this section relates specifically to context strategic planning.
The general principles of strategic planning and the available tools are broadly valid at either scale.
Key issues
In the context of management, strategic farm planning is designed to produce three outputs:
•
•
•
Most obviously, produce a document or a plan to guide subsequent action;
Some value added to the actors and institutions involved; this is likely to come about from the mutual
learning and debate which is intrinsic to the farm planning and bargaining exercise; and
A shared commitment to the vision and the measures agreed upon and set out in the plan.
A shared commitment needs to embrace all of the main stakeholders–the local authorities, the
government agencies, the voluntary sector, local business, the various local communities, and
certainly the anticipated funders who may include several of the foregoing, plus others. A good
strategic farm plan spends 60 percent on the process and 40 percent on content. The process of
17
strategic plan includes thinking, visualizing, conceptualizing, and decision-making and problem
solving. The process is actually more important than the plan itself because it provides an opportunity
for produces to buy in to the plan or it may just gather dust on some obscure shelf. The strategic plan
itself should be:
•
•
•
•
•
•
•
based on wide consultation and rigorous collection and analysis of baseline evidence, neither alone being
sufficient;
holistic and integrated in its treatment of relevant needs, issues, resources and action;
a statement of a shared vision and a shared commitment to achieve it. A vision in this context being an
expression of what should be, as distinct from what is in place today or what might become if nothing is
done;
selective and well-argued goals and the objectives and measures chosen to attain them should be clearly
stipulated, a mere wish-list is insufficient;
clear on the partners’ subsequent roles and responsibilities;
clear on the procedures for implementation and for monitoring and evaluation; and
genuine framework for future decision-making
A strategic plan symbolizes the notion of hierarchy such as:
•
•
•
operational plans or work programs (one year);
medium-year work programs; and
multi-year perspective programs.
Each of them spells out financial accounting procedures, defined tasks with their own earmarked
resources and quantified targets as well as precise dates and the unambiguous allocation of
responsibility.
Strategic farm planning consists of two key activities:
•
•
Technical activity: This relates to the collection and analysis of information on the area, the execution of a
program of consultation, the elaboration of a range of possible goals, objectives and measures, the
definition of possible projects and programs, fashioning of appropriate methods of implementation,
monitoring and evaluation; and
Political activity: This relates to the making of choice and the setting of priorities and taking shared
responsibility.
At the heart of strategic farm planning for rural development, different bargains, persuasions and
compromises of the various stakeholders are involved and an acceptance of conflict or at least
disagreement are often the norms. Moreover, strategic farm planning should have clear lines of
accountability and the process should spread over several months to conduct a series of meetings at
which agreement is reached on the main elements of the farm plan. Strategic farm planning for local
rural development needs to be firmly founded on:
•
•
•
•
The agreement of main actors: both the technical and political process should be integrated to start
momentum within six months that the maximum time available to move to an agreed and published plan;
Actor inclusion: the local authorities, the government agencies, the voluntary sector, local business, the
various local communities;
A clear notion of development as virtuous or honest spiral of change: focused primarily on economic,
social, cultural, political and environmental concerns; and
The temptation to squander/misuse scarce resources on gap-filling: this focused on how can rural
development best be initiated and supported with the scarce resources available.
Stages of farm strategic planning
There is no a universally accepted model of strategic farm planning, but most commentators typically
indicate five essential stages. These stages are now considered with local rural development on mind.
The five essential stages of strategic farm planning are:
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•
•
•
•
•
Clarifying the context – this is the diagnostic stage to define the key concerns that demand attention to
fashion practical measures;
Agree on a vision, goals and objectives – crystallizing vision, goals and objectives in clear, concise
language upon which all or most can agree. Vision, goals and objectives should be comprehensive and
realistic firmly based on the evidence of the diagnostic work;
Deciding on the main measures or actions – concerns how goals and objectives are realized given the
resource available and the constraints at work;
Establishing procedures for implementation – deals with implementation in greater depth. Operational
plans, balance between proactive and reactive projects, soliciting and assessing project proposals, matching
finance to make available with the working program and considering the in-house decision making structure
and procedures to distribute responsibilities between staff; and
Establishing procedures for monitoring, evaluation and the updating plans – monitoring and evaluation in
detail the progress of the plan, continuing relevance and effectiveness in achieving the desired results.
Implementation
Different countries have different institutional developments. Some countries have public while others
have private or both. The mix will differ depending on nation’s history, institutions, and political
philosophy. One lesson to be learnt from past failures is avoid extreme, exclusive or restricted
ideological commitment either to free market capitalism or to socialism. With demands, institutional
building takes place entirely either in the private sector or entirely in the public sector. The search for
complementarities between private and public roles and a pragmatic focus on problem solving appear
to be a more effective and efficient approach to implement farm management and rural development
programs. Moreover, the decisive factors to implement farm management and rural development
programs are the improvement in population quality and advance in knowledge. A nation that cannot
sustain long-term institutional building and human capital improvement will never have a highly
productive industrialized agriculture.
In practice, there are so many farm plans as designs and as operational vehicles. There is little wonder
that too many plans fill too many dusty shelves. The challenge is how to narrow the wide gap between
the plan and development that actually happens on the ground. Here, it is very important to relate
implementation primarily to local area development programs, which themselves generally contain or
imply scores of individual activities or tasks to be accomplished over a number of years. Plan
implementation is explained by how long-term and how wide-ranging strategic plans hand over to
short-term and precise operational plans designed to put them into effect. This stresses the role of
individual tasks linked to strategic objectives, each with their own targets, costing, and allocation of
responsibility. Implementation notably concerns with the role of local development partnerships, with
community involvement and the promotion of entrepreneurship – each of them addressing the
challenge of mobilizing the various actors who are crucial to the development process. The point is
that implementation does not somehow automatically happen once a clear strategy and a succession of
operational plans have been agreed; it is not just a matter of systematically carrying out a
predetermined plan. Implementation must be creative and developmental it, fostering initiatives and
enterprises as projects, set within the plan, are solicited or devised, worked up into operational form
and subsequently supported through to their conclusion. As for a definition, it is suggested that
implementation is the process of putting into effect and successfully accomplishing the goals,
objectives, the measures and tasks contained in strategic and operational plans of a given farm or area
or region. Key issues
Many local development agencies can devise their strategic farm plans taking more time and energy.
However, the challenge of implementation consists of soliciting appropriate project proposals from
people and businesses in the area and choosing which ones to support and putting them into effect by
offering funding and other practical assistance. Much of the implementation is indeed about to put
plans on the ground to bring genuine development. Here, there are two fundamental questions to be
addressed.
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Influencing group
The first question concerns the balance between promoting discrete or distinct projects and seeking to
influence other actors and organizations whose work is relevant to farm development. This
influencing other groups to be a part of implementation has often been neglected but can be very
valuable, especially as the other actors and organizations may well have substantially more resources
at their disposal. Persuading a large health authority to switch 1 per cent of its resources towards a
certain area or target population group may well do more for the disadvantaged residents of the area in
question than spending 25 percent of the budget of development agency on a specific healthcare
project in the rural areas. In its insistence or firmness, local authorities now accept a general
responsibility for the well-being of the residents they serve and do so, in close association with other
local agencies. Facilitation and influencing groups are key elements of plan implementation in farm
and rural development. In similar vein, voluntary sector compacts-agreement between public and
voluntary sector agencies in an area set out how the agencies will work in partnership to nurture
community activity and generally improve the quality of life of local people. Again, influencing other
stakeholders is a key element of implementation. Networking is another best approach for systematic
cultivation and nurturing of contacts among individuals who are influential either in their own right or
by dint or impression of their position in other organization has emerged as a major tool of
implementation in recent years. The task is to keep such people informed of your concerns and
activities to solicit their supports for the rural development. Practically, this needs devoting resources
to appropriate communication media – websites, newsletters, seminar, exhibition and the like to build
up some sort of membership based on people with shared concerns. It would be an interesting
research exercise to take a sample of recent rural development programs and assess what proportion
of their eventual success arose from influencing others as district from their direct support of funded
projects. Proactive and/or reactive
The second key issues for farm and a local rural development agency concerns with the proper
balance between proactive and reactive projects. Proactive projects are those devised and carried out
by or for the development agency itself whereas the reactive projects are those which emanate from
third parties, be the private individuals, companies, cooperatives or community groups brought to the
development agency with a request for funding and support of farm and rural development. At one
extreme, proactive projects play no parts in a development program when the development agent is
solely or entirely dependent on what happens to come forward for its consideration. At the other
extreme, proactive projects lay no part when the bottom-up notion or idea of development is virtually
forgotten or so dominate the rural development program. If the basic infrastructure of development is
already in place, a balance between proactive and reactive project is preferable. Local action groups
(LAGs) in that position have felt obliged to invest heavily in various awareness-raising initiatives,
training programs, demonstration projects and the deployment of project officers with a brief to go
round and stir things up. Thus, it is necessary to invest in flagship projects to involve the local action
groups in creating some substantial and very visible facilities around which private project promoters
might devise associated and generally smaller projects such as agro-processing and a mass of small
heritage tourism initiatives in the vicinity.
Project support
In the process of implementation, we underlined a balance between the proactive and reactive
projects. Thus, a budget should be shared to a number of reactive, bottom-up projects coming forward
from local project promoters with request for finance and support. Good practice in local development
is now explored the following approaches:
•
•
•
•
•
soliciting and working up project proposals;
selecting projects;
funding projects;
supporting projects; and
monitoring of projects
20
Success and failure of implementation
Where a sparsely population over wide areas are involved, farm or rural plan implementation failure
is expected. Because these duties would entail a series of steps: bringing people together, soliciting
and developing project proposals, helping people write their business plans, guiding project promoters
through the financial and bureaucratic maze or mess, taking the proposals to committee and
undertaking the subsequent communication, follow-up and monitoring. Among the attributes, we need
energy, commitment, flexibility, networking skills, administrative competence and a grasp of what
does exactly rural development mean. Thus, it is inconceivable or unbelievable to think of any
progress without the participation of private individuals, small business firms, companies,
cooperatives, and community groups.
Other factors that help to determine the degree of success enjoy by farm and local development
programs run along LEADER lines, which include:
•
•
•
enjoying good relations with both local authorities serving the area and the major program funders;
having a well-balanced and effective local partnership; and
enjoying a running start (raising awareness, organizing training programs, developing entrepreneurship,
building network etc.) in the sense of being able to build upon previous endeavors to promote local
development in the area, which will have done some of the groundwork
It is important to note that the overall progress in terms of project implementation and fund approval
and outputs achieved is slow in most areas of developing countries. The four main explanations are:
•
•
•
•
setting up of the local action group and of the regional machinery for overseeing them and for channeling
project funds via the national programs;
Underestimate the time required to build capacity and form partnerships within rural communities;
The complex and bureaucratic nature of the project application process being beyond the local level; and
Inadequate resources devoted to project development and the project application process at the local level in
some areas.
Finally, implementation of farm and rural development plans/programs should be evaluated based on
the accomplishment of objectives specified by the project support group at the outset. It generally has
three components:
•
•
•
Educational: concerning the level of competence attained and any behavioral change on the part of people
engaged in the business or project;
Economic: concerning the effect on the firm’s turnover, employment, individuals’ income etc.; and
Developmental: concerning effects on the local dynamic focusing on any spin-off or offshoot effects on the
local area.
Evaluation of the implemented farm and rural development plans/programs should always be based
on strong empirical facts; simply comparable facts between the “before” and “after” situations with
the aim that the trainer and trainees are fully involved in the evaluation exercise.
Evaluation
Evaluation is a complex, time-consuming and resource-hungry process. It follows that it is important
to reflect periodically and with as much strictness as possible on whether it is achieving what has been
intended, and if not, why not? It is this process of meticulous or precise reflection upon the degree of
achievement to which the work evaluation is generally applied.
Evaluation is a systematic analysis of performance, efficiency, and impact in relation to the
objectives. It is a periodical assessment of achievement to draw lessons from experience in order to
adjust existing action and to modify and improve effort. Evaluation can be defined as putting a value
on work undertaken over a period. More specifically, it is about assessing whether objectives set out
in a plan are actually achieved, why some activities are more successful than others are, and how
strategies can be improved. Evaluation should not be confused with monitoring – an equally necessary
21
exercise but monitoring is much more limited in purpose, scope and complexity. Thus, monitoring is
primarily about the recording of events as distinct from understanding and interpreting their
significance. It is essentially a mechanistic exercise charting actions over time, for example projects
started, money expended, enquiries received or meetings addressed, and asking in effect whether we
are on the right track or not. Evaluation is more demanding and it is a systematic analysis of
performance, efficiency and impact in relation to objectives, its ultimate purpose being not to
pronounce a verdict but rather to draw lessons from experience in order to adjust existing action and
to modify and improve future effort. The evaluation of an action, operation, project, or program
means to examine the achievement of the context in which it is applied and to assess its effect with
respect to the intended objectives. Evaluation is fundamentally about establishing and
elucidating/explain the degree of their attainments. The evaluation process always consists of
measuring deviations and analyzing the reasons for such deviations. To elaborate a little more on the
purpose of evaluation, it is important to involve more stakeholders in the local development process.
The points to be considered are:
•
•
•
•
Accountability and value for money: To help the promoters and founders of the program, decide
whether the money has been properly spent on the targets;
Management: To help the managers of the program, it is necessary to identify ways in which the
program’s execution might be made more effective and/or efficient in the time that remains;
Learning: To help the policy makers as well as various commentators and critics, gain insights and
understanding that might be useful elsewhere or in successor programmers. This learning process should be
related particularly to the relationships between inputs and outputs and between causes and effects; and
Empowerment: To enhance the skills, knowledge and commitment of those involved in the rural
development programs. Empowerment assumes and indeed requires that those involved in the development
program are also involved in its evaluation.
Empowerment is the most important tool of evaluation to further stimulate rural development
dynamic because it a part of the product in the process of rural local development. Indeed, evaluation
does not assess approaches but it empowers a tenet or principle of local development. The local
development process is enhanced where evaluation approaches mirror the participatory and capacity
building of rural projects. Empowerment is, therefore, the ethos, culture, or philosophy of local
development process.
Key issues
In the rural development context, evaluation has various purposes; it can be carried out at various
levels and at various times. As far as levels are concerned, an evaluation can focus national or
international program. As for timing, evaluation can be useful in four contexts:
•
•
•
•
Before a program or project get underway – effectively an exercise in trying to predict the impact or
consequences of the measures planned;
During the program or project – to identify ways of improving performance and management;
At the end of the program or project – to assess immediate impacts or outcomes; and
Sometime afterwards – to pick up long-term consequences and to allow the more matured reflection that
comes from standing back a little.
In deed, there is a case for evaluation being undertaken more or less continuously during the life of a
program or a project, as a part of the normal process of management, though on-going evaluation of
this kind can be expensive and distracting. The evaluation of a local development program is rarely
easy. Consider the challenge of evaluating an integrated rural development program or project can be
for three or four years for an area with about 50,000 people spread across perhaps 1000 sq. km. Some
of the problems related with program evaluation are:
•
•
inadequate statistics (employment, unemployment, income, social deprivation etc.) for either the baseline
year (the program started) or for the present year (three or four years after the program started); and
any effects of the rural development program such as upturn or downturn of the national economy
22
With that avenue or path of enquiry blocked, the research is forced to focus on the specific actions of
the program, trying to trace them through to their consequences on the ground. The most striking
example of a program is the jobs created for jobless people. However, such employment does no tend
to be true if it ignores dead weight problem (the extent to which the jobs would have come about
anyway) and displacement problem (the extent to which the jobs were already in existence in other
areas with less suitability and premises or building elsewhere in the area). More fundamentally, farm
and rural development programs are complex and multi-dimensional processes. They generally
comprise multiple actions, pursued by multiple actors in pursuit of multiple goals. ‘What affects what’
is difficult to entangle because the intangible nature of some outcomes being pursued in farm and
rural development is a culture of enterprise or a greater sense of local identity. Farm management
application is a long-term process, whose full effects are expected to emerge after many years. Thus,
program complexity, inherently intangible outcome, and delayed consequences produce one or two
unfortunate results. In this case, either the valuable outcomes of the program get to be overlooked by
the over-technocratic evaluators concerned only to put ticks in the boxes or else they are exaggerated
by a rather complacent or self-satisfied program manger that consciously lacks more tangible and
visible outcomes on the ground. Given all these difficulties, it might be tempting or appealing to
conclude that a genuinely serious and useful evaluation of farm and rural development is impossible.
However, this is not an option or excuse for not to carry out evaluation. An assessment is still needed
to prove if doing a program worthwhile or not. When some of the difficulties listed above are linked
to farm and rural development, two sorts of evaluation are really of very little value:
•
•
A simple comparison of before-and-after snapshots of certain key indicators (jobs created, business started,
trainees trained, and varieties developed.); and
Formal analytical approaches of the cost-benefit analysis type that are often quite usefully applied to
defined sectoral programs in agriculture. For example, a local project such as the construction of a bypass
around a certain town.
It is important to underpin or support that rural development demands the use of other tools such as
multi-dimensional models/approaches, well-trained evaluators, more qualitative and quantities
analyses, strongly participative stakeholders and the use of indictors in the appraisal of development.
Guiding principles of evaluation
Most evaluators of multi-dimensional, multi-purpose, multi-project rural (local) development
programs have tended to endorse or focus on three questions:
•
•
•
What were or are the program’s objectives?
How far were or are they being realized? and
Why or why not realized?.
The third question forces attention to focus on the so-called or alleged chain of causes between the act
and the consequence and it is an elucidation of that chain that really makes the exercise worthwhile.
The best way to evaluate most farm and rural development programs is to focus on their objectives,
assess the degree of their attainment, and then try to seek out and understand the complex process of
cause and effect that underlie that attainment or lack of it. In this context, the evaluators must keep
sight of multi-purpose, multi-action and multi-actor nature of farm and rural local development
quantified what can be quantified and delivered or investigated deeply using mainly qualitative
methods into the how? why? and why not? Going on from this premise, the precise choice of the
evaluation method will depend on many factors including the real purpose of the evaluation, the
complexity and scale of the program, the availability of data, the likely co-operation of the various
stakeholders, the evaluator’s resources of time and money.
•
•
Keep the focus on outcomes (intended and unintended) and on the processes that led to them; quantify what
you can but do not also ignore what you cannot;
Involve the various stakeholders as subjects in the evaluation and not just as objects;
23
•
•
•
•
•
•
Use careful reference to documentation and initial exploratory interviews to start with the originally
intended goals, objectives and intended outcomes, tangible or intangible, explicit or in some ways implicit;
Refine set of goals, objectives and intended outcomes into more tangible indicators using eclectic or
diverse or free sources;
Make a first attempt at defining how far goals, objectives and intended outcomes have been or are being
attained, or at least if things are moving in the desired direction;
Use evidences as a focus for a retrospective exploration or study of what happened and enquired how and
why goal attainment was achieved or missed. Semi- structured interviews with a wide range of actors,
documentary analysis and participant observation will be invaluable at this stage; and
Synthesize and critically appraise the possibly divergent evidence emerging and attempt an exposition of
the links between the inputs and outputs and the causes and effects that are at the heart of a development
program;
Test out that draft exposition by revisiting your sources and seeking their reactions to the rural development
accomplishing in the area.
Finally, an evaluation is undertaken based on the objectives specified by farm and rural development.
It is, therefore, important to consider how far the project support groups at the outset. It generally has
three components:
•
•
•
Educational: Concerning the level of competence attained and any behavioral change on the part of people
engaged in the farm business or project;
Economic: Concerning the effect on the farm’s turnover, employment, and income; and
Developmental: Concerning the effects on the local dynamics focusing on any spin-off effects on the local
area.
The evaluation is always strongly empirical. It simply involves trying to compare the ‘before’ and
‘after’ situations. The trainer and trainees are fully involved in the exercise.
From evaluation point of view, farmers should adopt innovation and quality management programs
and/or may have to restructure their farm business in order to improve product quantity and quality,
reduction costs and services. Moreover, farmers in developing countries have to continuously evaluate
their farm processes, meaning the way they do things on their farms.
•
•
Typical operational processes on a grain farm including land preparation, planting, fertilizing, crop
protection, harvesting and marketing (e.g. adding value, packing, transporting, after-sales services); and
Typical management processes including monitoring performance (crop growth, product quality and labor
productivity), managing information (seeking and utilizing relevant information, managing assets (land,
machinery, oxen and cash flow, managing human resources (education, training, empowerment, conflict
resolution), planning and resource allocation
Producers have to study the above each process I detail and consider the potential for improving a
particular process or altering it completely so as to achieve their objectives (increase in productivity,
higher quality products, reduction of cost per unit product, improved timeliness and sustainability of
environmental, social, human and manufactured capitals). What happens when farms depend on
markets?
•
•
•
Farmers should produce higher quality products and services knowing consumers needs and expectations;
Farmers should adopt quality management to improve product quality and to reduce cost per unit product
knowing food processors’ needs and expectation; and
Farmers should exactly know how much to produce and at what cost to produce?
Finally, the adoption of new technologies should increase productivity, reduced production cost per
unit product and these, in turn, drive down real commodity prices.
24
In conclusion, many developing countries are rich in natural resources but they remain poor because
their social institutions which are either inadequate or not oriented to meet new economic and social
needs. Moreover, the use of natural resources and the implementation capacity of any country depend
heavily upon the human capital and the level of education and training. Increase in productivity arises
not from technological change and availability of natural resources alone but from improvements in
human capital, institutional innovation, and effective use of the available biological and physical
capitals. Thus, human capital is the most important factor to assess and decide on production and
technological matters (invention, imitation, adoption, use, etc.). Lack of access to technology, market
information, and transport are the major obstacles to the commercialization of small farming system
in developing countries particularly in Ethiopia. Perhaps the most important market constraints are
access to transport and market information. For instance, most producers tend to sell their produces at
lower prices in the local markets because they have few opportunities to sell outside these markets
due to lack of transport and market information. Where producers make farm gate sales, information
on prices prevailing in other markets is useful in setting appropriate prices at local markets. With
better market information, however, there is potential for smallholders to diversify what they produce,
vary their times of planting and target for higher value products for different marketing channels.
Transport posed a problem for producers wishing to sell to the independent wholesalers in big towns
due to the following facts:
•
•
•
Rural trucks are expensive to use terminal markets;
Truck divers are reluctant to go to big towns where they have to unload the relevant produces and wait long
while it is inspected;
Most of the truck drivers are less familiarized with big towns.
Some producers in Ethiopia report that they have few sources of reliable marketing information to sell
their farm produces to the terminal markets. However, this source of information is not entirely
trusted, as people like to keep details of attractive opportunities to themselves. Improved marketing
information flows are valuable. However, farmers still have to overcome other constraints to enhance
production and marketing activity. This situation provides two challenges to the professionals
engaged in agriculture. First, if small farmers are to be empowered to play any constructive role in the
development of agriculture, it is necessary that they get access to support services. However, these
services should not be done on an ad hoc basis. Second, it is necessary to provide target support to
small farmers who have access to land and other assets. It is possible to create a ‘small farmers
miracle’ among small farmers by providing access to support services on a priority basis. The accent
here should be on factors that will induce farmers to produce in as short a time as possible, such as
direct price support for marketed output and measure to decrease their input costs by providing
mechanization services to plough fields and thresh harvests.
25
2. Improved Crop Production
2.1. Cereals Improved Maize Varieties
M
AIZE VARIETY is a group of plants that are distinct from other groups and its identifying
characteristics are constant in time and space. There are two types of maize varieties: open
pollinated varieties (OPVs) and hybrids. OPV is a population and/or a composite that is
different, relatively uniform, and stable. Examples of OPVs are Melkasa-2, Gibe-1, Gambela comp-1
and Hora. Hybrid is produced from two or more genetically distinct parents called inbred lines. Based
on the number and genetic composition of parents, maize hybrids can be single cross (BH-540,
BHQPY-545), three way cross (BH-660, BH-670, BH-543, BHQP-542, AMH-850) and top cross
(BH-140, AMH-800). The main advantage of OPVs is that farmers can save their own seeds for
planting the following season for at least three years. However, hybrids have higher grain yield and
are more uniform than OPVs. The disadvantages of hybrids are farmer should get F1 seed every year
and there is significant yield reduction if farmers use F2 grains as seed. For example yield reduction of
23% for BH-540, 18.9% for BH-660 and 11.7% for BH-140 have been recorded when F2 grains of the
hybrids were planted under research station conditions).The National Maize Research Project has
recommended a number of OPVs and hybrids adapted to the different maize agro-ecologies of the
country (mid-altitude sub-humid, high-altitude sub-humid, low-altitude sub-humid and low moisture
stress areas). These maize varieties include white, yellow, QPM (quality protein maize, maize with
higher lysine and tryptophan content) and non-QPM. Improved maize varieties (both OPVs and
hybrids) give high yield when they are planted in their adaptation areas. List of recommended maize
varieties, their areas of adaptation and some of their important agronomic characteristics are presented
in Table 2.1.
Agronomic Practices
Improved varieties give high yield whenever they are planted under the recommended management
practices in their adaptation areas. Improved maize agronomic practices include land preparation,
planting time, plant density (seed rate, and spacing), fertilization (type, rate and method), weed
control, cropping systems and soil and water conservation. Therefore, maize producers should strictly
follow the recommended management practices to exploit the yield potential of the improved
varieties.
Site selection and land preparation
Selecting appropriate site for maize production is one of the key factors to increase productivity and
production. Maize plant is sensitive to water logging, where water logging more than 24 hours at early
stage can kill the crop. Therefore, maize fields should be well drained and free of waterlogging
throughout the growing season. Maize grows best in deep and loamy soils with a pH range of 5.5 to
7.8.
26
Table 2.1. Released maize varieties with their agro-ecological adaptations and some agronomic characters
Crop
Hybrids
OPVs
Variety
BH-660
BH-540
BH-140
BH-543
BHQPY-545*
BH-670
BHQP-542*
AMH-800
AMH-850
Hora
Kuleni
Gibe-1
Gutto
Morka (improved UCB)
Rare-1
Melkasa-1
Melkasa-2
Melkasa-3
Melkasa-4
Melkasa-5
Melkasa-6Q*
Melkasa-7
Abo-Bako
Gambela Comp-1
Year of
release
Altitude
(m)
Rain fall
(mm)
1993
1995
1988
2005
2008
2001
2001
2005
2007
2005
1995
2000
1988
2008
1997
2000
2004
2004
2006
2008
2008
2008
1986
2001
1600-2200
1000-2000
1000-1700
1000-2000
1000-1800
1700-2400
1000-1800
1800-2500
1800-2600
1800-2400
1700-2200
1000-1700
1000-1700
1600-1800
1600-2200
Low moisture stress
Low moisture stress
Low moisture stress
Low moisture stress
Low moisture stress
Low moisture stress
Low moisture stress
300-1000
300-1000
1000-1500
1000-1200
1000-1200
1000-1200
1000-1200
1000-1500
1000-1200
1000-1200
1000-1200
1000-1200
1000-1200
1000-1200
800-1200
1200-2000
900-1200
600-1000
600-1000
600-1000
600-1000
600-1000
600-1000
600-1000
900-1200
900-1200
Plant
height
(cm)
255-290
240-260
240-255
250-270
250-260
260-295
220-250
205-225
220-235
200-215
240-265
240-260
165-190
270-300
250-270
140-160
170-190
170-175
160-170
180-190
165-175
170-182
220-230
200-220
Ear
Placement
(cm)
145-165
110-120
105-120
140-150
120-140
150-165
100-120
105-125
120-130
100-120
130-145
130-140
90-110
145-180
130-150
65-70
80-90
75-80
70-80
80-90
70-75
80-90
120-130
105-115
Days to
Maturity
Seed
Color
160
145
145
148
144
165
145
175
183
170
150
145
126
180
163
90
130
125
105
125
120
115
112
116
White
“
“
“
Yellow
White
White
“
“
“
“
“
“
“
“
Yellow
White
“
“
“
“
Yellow
White
“
Yield (q/h)
Farmers
Research
centers
field
90-120
60-80
80-90
50-65
75-85
47-60
85-110
55-65
80-95
55-65
90-120
60-80
80-90
50-60
70-80
55-65
80-120
60-80
60-70
40-45
60-70
40-45
60-70
40-45
30-50
25-30
70-90
40-60
60-70
40-45
35-45
25-35
55-65
45-55
50-60
45-50
35-45
30-35
40-50
35-40
45-55
30-40
45-55
30-40
50-60
35-45
60-70
40-50
MSV
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
T
R
Disease reaction
GLS
TLB
T
MT
MT
MT
T
T
T
T
T
T
T
MT
MT
T
T
_
_
_
_
_
_
_
T
T
T
MT
MT
MT
MT
T
MT
T
T
T
T
MT
MT
T
T
T
T
T
T
T
T
T
T
T
CLR
R
MT
MT
T
MT
R
MS
T
T
T
R
T
MT
T
T
T
T
T
T
T
T
T
T
T
T=tolerant, R=resistant, MT=moderately tolerant, MS= moderately susceptible, MSV= maize streak virus, GLS=gray leaf spot, TLB=turcicum leaf blight, CLR=common leaf rust ‘‐’ = disease not important (MSV is important mainly around Gambebela, while GLS is important mainly in high rain fall areas) Rare‐1 is mainly for Hararge highlands while Morka is mainly for Jimma & similar areas with long rainy season * Quality protein maize, QPM (maize with high lysine and tryptophane content) Gibe‐1 is recommended for “Bone” (off‐season) production too. BH‐140 & BHQP‐542 are recommended for production under irrigation in the rift valley and similar areas too. NB: In addition to the varieties listed in this table, there are other varieties released for mid‐altitude sub‐humid agro‐ecology by Pioneer Seed Company and ESE. Pioneer hybrids are PHB3253, PHB30H83 (Tabor), PHB30G19 (Shone) and PHB30D79 (Agar). The hybrid released by ESE is ESE‐203 (Toga). 27
The effect of soil pH outside this range usually makes certain elements more or less available which
leads to the development of toxicity or deficiency. In general, maize can tolerate temperatures ranging
from 5 to 45oC. Frost areas should be avoided during site selection. Regarding land preparation,
plowing 2–3 times depending on the field situation is recommended. Conservation tillage is also the
other option with the application of herbicides.
Planting time
Planting dates should be based on the onset of the rainfall of the growing season in each agroecology/location. It is advisable to plant early whenever there is enough moisture in the soil to benefit
from higher soil fertility present at the beginning of the rainy season and to achieve physiological
maturity before the end of the rainy season.
Planting depth
If the seed is planted too deep, the seedling depletes food reserves before it emerges out of the soil
surface. On the other hand, leaving seeds on the surface or too shallow planting expose the seed to
damage by wild animals and desiccation. Therefore, the optimum depth of planting is 5 – 7 cm.
Plant density
Row planting is recommended for maize production. The optimum plant density differs for different
varieties depending on plant height, and maturity. For late/medium maturing varieties of mid-altitude
sub-humid agro ecology, the spacing should be 75 cm x 30 cm, one seed/hill (44,444 plants/ha) or 80
cm x 50 cm, two seeds/hill (50,000 plants/ha). Gutto is exceptional mid-altitude sub-humid agroecology variety, which requires spacing of 75 cm x 25 cm, since it is early and short. The spacing for
medium/early maturing varieties of low moisture stress areas (Melkasa-2, 3, 4, 5, 6Q & 7) and all
highland varieties should be 75 cm x 25 cm (53,333 plants/ha). For extra early maturing variety
(Melkasa-1) spacing of 75 cm x 20 cm (66,666 plants/ha) is recommended. Generally, seed rate of 25
kg/ha is recommended, but this may vary depending on seed size and planting density.
Fertilizer type, rate, method, and time of application
Maize plant uses different nutrients from the soil. Nitrogen, phosphorus, and potassium are required in
large quantities. Currently, only nitrogen and phosphorus are applied through chemical fertilizers in
Ethiopia. Fertilizer recommendations are location specific and recommendations for some areas are
presented in Table 2.2. Application of the whole rate of DAP at planting and split application of urea
is recommended. For highland areas, it is recommended to apply urea in three splits: 1/3 at planting,
1/3 at knee height and 1/3 at flowering. In addition, for mid-altitude sub-humid areas urea is applied
in two splits: half at planting and half at knee height. While, for the low moisture stress area the whole
dose of urea is applied at knee height. Band/side dressing/spot application of fertilizers is advisable
for efficient use of the fertilizers.
Table 2.2. Recommended fertilizer type and rate (kg/ha) for some locations and similar areas
Fertilizer
Adet
Haramaya
Ambo
Holetta*
Fertilizer rate (kg/ha)
Hawassa
Jimma Bako
DAP
150
100
100
150
100
Urea
200
150
200
200
200
* Holetta red soils, ** No recommendation for phosphorus at Pawe 150
200
150
200
Gimbi
Melkassa
Pawe
Gambela
150
150
100
50
**
150
100
50
In addition, well-decomposed manure and compost could be used as source of nutrients. Five t/ha
compost plus 50 kg/ha of DAP (applied at planting) and 35 kg/ha urea (top dressed at knee
height/Shilshalo) is recommended. Generally, the recommended rate of farmyard manure is 16 t/ha.
28
Weed control
Weeds damage maize crop mainly by competing for nutrients, light and water. Maize is very sensitive
to weed competition from emergence to flowering stage. Therefore, maize fields should be kept weed
free. However, for practical and economic reasons, twice hand weeding (the first one at 25 to 30 days
after sowing and the second at knee height) is recommended. Slashing at flowering stage is also
recommended. In addition, pre-emergence herbicides, primagram or gesaprim, at the rate of 4 – 5 l/ha
supplemented by hand weeding is recommended. Use of lasso-atrazine is also recommended at the
rate of 4-5 l/ha after planting but before emergence of the crop. Rotation or intercropping of soybean
with maize is recommended to reduce striga infestation around Pawe.
Cropping systems
Monoculture is not recommended for maize production. Increase in incidence of diseases, insect pests
and weeds, deterioration in soil structure, loss of topsoil by erosion and depletion of soil fertility are
the major problems associated with monocropping.
Crop rotation
It is the growing of different crops, one at a time, in a definite sequence on the same piece of land.
Maize crop benefits when rotated with legumes as legumes can fix nitrogen. Soybean, haricot bean
and other pulse crops are recommended for rotation with maize. In addition, niger seed followed by
haricot bean as precursor crop for maize is recommended around Bako and similar areas.
Intercropping
It is the practice of growing two or more crops simultaneously on the same field. Intercropping 75%
plant density of haricot bean into 100% plant density of maize during oxen-cultivation (Shilshalo) at
about 35 days after planting is recommended around Bako. Intercropping one seed/hill of haricot bean
within the same row of maize (80 cm x 50 cm, two seeds/hill) is also recommended around Jimma
and similar areas. In addition, intercropping of two rows of maize and one row of faba
bean/gomenzer/potato is recommended in the highland areas.
Relay cropping
A second crop is planted in maize field after maize crop has reached its reproductive stage of growth
but before it is ready for harvest in a practice. Relay planting of sweet potato at 50% flowering of
maize is recommended. In addition, relay planting of haricot bean starting from 50% flowering to 15
days after flowering of maize is also recommended.
Double cropping
It is cultivation of two different crops on the same field within the same season one after the other.
After green ear (‘eshet’) harvest of AMH-800 and Hora, chickpea/grass pea is recommended for
double cropping on Vertisols of central highlands. For Jimma and similar areas it is recommended to
plant, early maturing crops like tef and haricot bean after harvest of early maturing maize planted at
the beginning of the cropping season.
Soil and water conservation
The time span required for the formation and development of 2.5 cm of surface soil is between 100
and 600 years depending on the factors of soil formation. However, that 2.5 cm of fertile surface soil
could easily be lost over a 24 hours period by run-off erosion if it is not conserved and managed
properly. Contour farming, conservation tillage, and strip cropping are among the recommended
practices for soil erosion control in maize production.
29
Pest Management
Many insect pests and diseases have been recorded attacking maize in the field and in the store in
Ethiopia, but only a few are economically important. The major insect pests are maize stem borers,
termites, maize weevil and grain moth. Gray leaf spot (GLS), turcicum leaf blight (TLB), common
leaf rust (CLR) and maize streak virus (MSV) are the major diseases.
Control
Stem borer (Busseola fusca)
Cultural control: Removal of volunteer plants and alternate hosts (napir/elephant grass, wild
sorghum, sorghum tillers grown from ratoon etc) is recommended. After harvest, horizontal
placement of infested maize stalks in the sun for 4 weeks is also recommended. Besides, the infested
maize stalks should be cut at soil level, so that most larvae could be removed from the field. In
general, early sowing as soon as the rain starts can offset the damage caused by B. fusca.
Maize/legume intercropping is also effective in controlling stem borer. However, it is not advisable to
plant maize and bean simultaneously in the same row in stalk borer hotspot areas.
Biological control: Beauveria bassiana and Metarrhizium anisopliae among fungi and Cotesia.
sesamiae and C. flavipes among parasitoids are the first candidates for biological control of maize
stem borer. But these biotic agents need further studies on formulation, mass rearing/production and
commercialization.
Botanical control: Chinaberry (Melia azedarach L.), endod (phytolacca dodecandra L.) and
pepper tree (Schinus molle L.) at 2, 10 and 20 kg/ha for fresh leaves; 1, 2 and 10 kg/ha for dried
leaves; 10, 20 and 30 kg/ha for fresh fruits, and 2, 10 and 20 kg/ha for dried fruits, respectively, are
recommended. Neem seed and pyrethrum flowers at 8% concentration are also recommended. For
efficient control, more than 2 applications are needed. But they need commercialization.
Chemical control: Diazinon 60% (1-2 l/ha), Ethiosulfan 35% (2-2.5 l/ha), carbaryle 1.28 kg/ha a.i,
cypermetrin (16 ml a.i/ha) and carbofuran 1.5 kg a.i/ha are recommended.
Termites Cultural control: Mulching (maize stover and other grasses), intercropping maize with soybean at
the ratio of 2:1, crop rotation (maize with legume), spread of wood ash around the base of the crop
and queen removal are recommended. In addition, use of lodging resistant and early maturing maize
varieties are advisable.
Botanical control: Application of neem seed powder at 45 kg/ha and ‘abbeyi’ (Maesa lanceolata)
leaf powder at 40 kg/ha are recommended.
Chemical control: Diazinon, 60% EC at 2.5 l/ha, GUFOS at 200 ml/ha (for spray) and fipronil at
10-11.7 ml/kg (for seed dressing) are recommended. Storage insect pests control
Adoption of the following integrated pest management package is recommended to ensure better
storage of maize grain and seeds with minimized quantitative and qualitative losses:
Harvesting: Harvesting at proper stage (timely harvesting), Ear inspection/sorting: Before shelling, ears should be inspected for pregerminated ears,
mouldy/diseased ears, insect damaged ears, etc. and removed. Shelling: Shelling at proper moisture content (13-14%), cleaning, and disinfecting the sheller before use,
maintenance of full-feed to sheller to avoid grain crashing by the shelling machine, and checking for
mechanical damage of the grain and taking correction measures are recommended during shelling. 30
Grain treatment and storage management:
o
o
o
o
o
o
o
Proper and careful drying of grains to safe moisture level after shelling (12.5%)
Maintenance of sanitation and hygiene of store as well as grains 4 to 6 weeks prior to placing new harvest for
storage.
Use of both preventive and protective chemicals (Actellic 2% D and Malathion 5% D at 50 g/qt)
Fumigation of granaries and warehouses with chemicals such as phostoxin, quickphox and others.
Use of plant products and inert materials (Chenopodium plant powder at 1.25% w/w, neem seed powder at 2%
w/w, vegetable oils at 5 ml/kg, triplex at 0.1% w/w, melkabam at 1% w/w, SilicoSec at 0.05% w/w, wood ash at
2.5% w/w and small seeded crops like teff at 5-10% w/w)
Use of improved storage structures (sealed and elevated with rodent baffles)
Use of air tight storage (modern hermetic cocoon)
Diseases control
Grey leaf spot (Cercospora zeae-maydis)
Cultural control: avoid infected plant debris, recommended spacing between and within rows, deep
ploughing to bury crop debris, crop rotation and early sowing (at the onset of rainy season
Resistant/tolerant varieties: Use varieties with relatively better resistance/tolerance to the
disease. Example: BH-670, BH-660, Kuleni, and others.
Chemical control: spraying of benomyl at the rate of 0.5 kg/ha is recommended. Turcicum leaf blight (Exserohilum turcicum)
Cultural control: use of adequate inorganic fertilizer in combination with farmyard manure,
intercropping with legumes and crop rotation, use of optimum seeding rate, spacing, and early
planting of maize are recommended.
Resistant/tolerant varieties: using varieties relatively resistant/tolerant to the disease. For
examples, BH-670, BH-660, Kuleni and others
Chemical control: use of combination of mancozeb and propoconazole at the rate of 2 kg active
ingredient per ha of maize (2-3 times of application at ten days interval)
Common leaf rust (Puccinia sorghi)
Cultural control: Timely planting, intercropping maize with legume and crop rotation reduces the
level of infestation.
Resistant/tolerant varieties: using varieties relatively resistant/tolerant to the disease, for
example, BH-670, BH-660, Kuleni, and others
Chemicals control: combination of mancozeb and propoconazole at the rate of 2 kg active
ingredient per ha of maize (2-3 times of application at ten days interval) Maize streak Virus
Cultural method: early sowing, inspection, and rouging infected plants especially at early stage.
Resistant varieties: Use varieties like Abo-Bako and Gambella Comp-1 Chemical control: Controlling the vector (Cicadulina mbila) that transmits the disease using
insecticide
Ear and kernel rot disease (Diplodia zea, Fusarium monoliforme and Gibberela zea)
Chemical control: seed dressing with fungicide Luxan TMTD at 200-500 g/q of seed
31
Wheat Production
Wheat (Triticum spp.) is widely produced in the highlands and mid-altitudes of Ethiopia. Out of 18
major agro-ecological zones (AEZ) in the country, wheat is grown in more than eight AEZ. The major
wheat growing areas include Arsi and Bale in the south-eastern, Hadiya and Kambata in the south,
Shewa in the central highlands, and Gojam, Gondar, Wello and Tigray in the north-western and north.
There are also several secondary areas of wheat production in the country. Many other crops are
produced in the wheat growing AEZs. Most of these crops particularly pulses and oil crops are
important rotational or precursor crops in a wheat-based production system.
Bread wheat (T. aestivum L.) and durum wheat (T. turgidum ssp. durum L.) are the two major species
of wheat cultivated in Ethiopia. Durum wheat is traditionally grown on heavy black clay soils
(vertisols) of the highlands. However, owing to its higher productivity per unit of land, the area under
bread wheat production has been increasing in recent years as compared to that for durum wheat.
The productivity of wheat in Ethiopia is low compared to other wheat producing countries of the
world. Reasons for this are: (1) the use of traditional production system; (2) the influence of biotic
(e.g. diseases) and abiotic factors; and (3) the unavailability of production inputs (e.g. improved
seeds) and/or suboptimal use of recommended packages. Since the inception of bread wheat research
in Ethiopia, fairly high number of improved bread and durum wheat cultivars have been released to
farmers most of which were developed from introduced germplasm, mainly CIMMYT, Mexico.
Tables 2.3 and 2.4 indicate released bread wheat and durum wheat varieties along with their main
characteristics and suggested production domains. Generally, it is wise to recommend here that the
potential areas of cultivation described for each wheat variety should be supported by adaptation
trials. The recommended agronomic and other crop management technologies of wheat production are
also outlined here. Nevertheless, the recommendations provided here could vary from place to place
depending on differences in the agro-ecology where the technology is to be adopted.
Soil requirements
Wheat performs well on black clay, red clay and brown clay soils. The soil pH should be higher than
5.5. Waterlogged Vertisols are not generally suitable for wheat production. But with special soil
management practices (broad bed and furrow or BBF), such soils can become more productive. Ridge
and furrow (RF) can also give good results.
Agronomic practices
The combined use of appropriate cultivars in their recommended agro-ecology and improved farm
management practices could result in the exploitation of their maximum yield potential. It is essential
to strictly grow a variety by applying a good farm management practices in order to get the maximum
benefit. Following are the outline of some recommended agronomic practices which could be used by
wheat growers of Ethiopia.
Land preparation and tillage
Depending on the type of soil, rainfall and cropping systems, 2-4 passes with a local plow (Maresha)
is necessary prior to seeding. On light soils in order to reduce erosion, using total weed killer
herbicides can minimize frequency of tillage. Glyphosate at product rate of 2 liters/ha can be applied
1-2 times during fallow period depending on weed infestation level. A broad bed maker (BBM)
having 8-12 cm width and which allows a drainage furrow of 15-20 cm between beds have been
found to increase wheat grain yield by 50-144% in vertisol areas. The ridge and furrow method of
land preparation by local plow facilitates drainage of excess water from a field through the furrows
and can increase wheat grain yield by 33%. Camber beds of 7-11 meter width made by tractor could
32
facilitate drainage of waterlogged fields and enhance wheat grain yield two to three times relative to
traditional land preparation.
Sowing date
Sowing dates generally depend on location, soil type, onset and distribution of rainfall and the variety
to be used. It should be noted that untimely planting (early or late) is likely to result in reduced yield.
Late maturing varieties require early planting relative to early varieties.
Seeding rate
175 kg/ha for semi-dwarf varieties with low tillering capacity, broadcast seeding and covering by
local plough. 150 kg/ha for intermediate and semi-dwarf varieties with good tillering capability
broadcast seeding and as low as 125 kg/ha for row planting with proper seed drilling machine.
Fertilizer rate
Fertilizer rates should be based on recommendations for specific areas. Fertilizer rates vary from
location to location depending on the fertility status of the soil, cropping sequence and varieties used.
The whole amount of DAP should be applied at sowing, whereas the nitrogen rate is split applied, 1/3
at sowing and 2/3 at mid-tillering (35-40 days after emergence).
Crop rotation
Rotation of wheat with non-cereal crops could provide several benefits to the subsequent
wheat crop. Improved soil-structure, added organic matter and reduced weed, disease and
insect pest problems are some of the advantages of crop rotation. The soil fertility level could
also be enhanced if the preceding crop is a nodulating leguminous crop, which could make a
symbiotic association with Rhizobium bacteria that fix atmospheric nitrogen. Wheat grain
yield after faba bean has increased compared to continuous wheat. Experiments also showed
that a precursor oil crop, mustard, increased wheat grain yield substantially as a result of
certain rotation advantage provided by the oil crop.
Weed management
In wheat-based cropping systems, weeds can be managed in several ways. Seedbed should be free of
weed seedlings at seeding. This can be facilitated by uprooting the weeds, plowing or harrowing, or
by applying total weed killer herbicides before seeding. Practicing crop rotation with non-cereals
would facilitate the control of grass weeds such as Bromus spp., Phalaris spp., Setaria spp. and Avena
spp. Use of clean seed reduces emerging weed population in wheat fields. Twice hand weeding (25-30
and 55-60 days after emergence) is recommended if labour is available. If labour is limiting, a number
of herbicides are recommended to use in wheat. 0.8-1 liter Puma Super or 0.75-1 liter Topic per ha
are recommended against grass weeds in wheat. 1 liter 2,4-D, 100 ml Derby or 1 liter Starane-M per
ha are recommended against broadleaf weeds. Depending on the growth stage of the weed and the
prevailing weather conditions half product rates of tank mixed Puma Super and Starane-M can be
used to control both grass and broadleaf weeds. These chemicals could be sprayed with a spray
volume of 200-400 liters of water per ha. Derby and Starane-M are compatible with Puma Super and
Topic to be sprayed tank mixed but 2, 4-D does not. This minimizes repeated entry to the field.
Pest control
The best and economical way of disease control/or prevention is to use resistant/or tolerant wheat
varieties. Alternative methods of pest control would be the use of crop rotation, fallowing of land and
chemical control option.
33
Recommended chemicals for pest control
Rusts
To control wheat rusts spray 1/2 liter Tilt 250 EC mixed in 150-200 liters water per ha when disease
severity is 5% or more. The second spray may be done 3-4 weeks later, if necessary. The other option
is to spray 1 liter of Baylaton mixed in 150-200 liters of water per ha when disease severity is 5% or
more.
Armyworm
Spray 2-3 liters of Malathion 50 EC or 1.5 kg of Carbaryl powder in 250-400 liters of water/ha. 1
liter Fenetrithion 98% ULV or 1.5 liter Malathion 95% ULV may be applied on one hectare of crop
land.
Aphids
1 kg of Primor 50% WP or 1.5 liter of Chlorimyphos 50% EC in 300-500 liters water for one
hectare.
Grasshoppers
250 g Carbaryl 85% WP mixed with 25-30 kg barley bran or wheat bran and spread on one hectare,
or 0.75 liter of Fenethrithion 98% ULV for one hectare, or 1.5 liters of Malathion 95% ULV for one
hectare.
Harvesting and threshing
It is advisable to harvest the wheat crop soon after maturity to avoid or minimize loses from
shattering and sprouting, in case of unexpected strong wind and showers of rain. Traditionally, wheat
is harvested manually and threshed on the ground using animal power. Farmers use the force of wind
for winnowing and cleaning. Modern harvesting and threshing methods, however, involve use of
combine harvesters and/or motor mounted threshers for stationary threshing.
Storage
Different storage pests can attack the wheat grain in the store. Proper drying of grains to about 12.5%
moisture level is necessary before putting grains in storage facilities. Grain store should be
constructed in a way that it is rodent and bird proof and must be free of weevils before storing grain. It
is advisable that the storage facility is placed in a well-ventilated area.
34
Table 2.3. Agronomic characteristics and recommended production domains of released bread wheat varieties.
Variety
Dereselign
K6290-Bulk
Year of
release
1974
1977
Plant ht.
(cm)
90-106
110-125
Maturity
(days)
100-125
128-131
Rainfall
(mm)
>500
>500
K6295-4A
ET-13A2*
Pavon-76*
Mitikie
Kubsa*
Wabe
Galama*
Abola
Magal
Tusie*
Katar
Shina
Tura
Hawii*
Mada-Walabu*
Simba*
Sofumar*
Wetera
KBG-01*
Sirbo
Bobitcho
Tossa
Digelu*
Meraro*
Senkegna
Tay
Jiru
Warkaye
Alidoro
Dinknesh
Gasay1
Menze
Millennium*
1980
1981
1982
1994
1995
1995
1995
1997
1997
1997
1999
1999
1999
2000
2000
2000
2000
2000
2001
2001
2002
2004
2005
2005
2005
2005
2006
2006
2007
2007
2007
2007
2007
100-115
105-120
90-100
110-125
90-100
90-100
100-125
75-110
60-100
75-110
90-100
95-105
90-100
90-100
95-110
90-100
90-100
90-100
80-90
90-100
90-100
75-85
95-110
70-90
75-100
85-105
70-78
63-99
90-110
59-80
84-97
60-70
70-90
128-131
127-149
120-135
125-135
120-140
120-140
120-155
128-131
113-124
125-130
110-134
100-120
120-150
105-125
100-125
100-150
125-150
120-150
80-100
85-105
95-105
134-143
100-120
110-120
105-125
104-130
154
136
118-180
145
118-127
154
90-120
>600
>600
>500
>600
>600
>600
>600
>600
>500
>600
>600
>600
>600
>500
>600
>600
>600
>600
>600
>600
>500
900-1200
>600
>500
>700
>700
911-1200
900-1200
≥500
900-1200
>700
<904
>600
Altitude (m)
1650-2200
1800-2200
Yield
(q/ha)
24-40
30-50
Breeder/
Maintainer
KARC /EIAR
KARC /EIAR
1900-2400
2200-2900
750-2500
2000-2600
2000-2600
<2200
2200-2800
2200-2700
1800-2400
2000-2500
2000-2400
2800-2500
2200-2800
1800-2200
2300-2800
200-2600
2300-2800
2000-2400
2000-2400
2200-2800
1800-2800
2400-3000
2000-2600
1800-2800
1900-2800
1900-2800
2600-3100
2400-300
2200-2900
2400-3000
1890-2800
2800-3100
2000-2400
30-60
30-60
30-60
30-70
50-70
40-60
45-70
40-65
30-50
40-65
30-60
35-65
40-55
15-40
35-45
30-50
40-50
20-45
66
61
30-55
36
30-50
30-50
60
60
44
29-33
26-52
20-35
44-50
19-33
30-50
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
ADARC/ARARI
KARC /EIAR
KARC /EIAR
SARC/OARI
KARC /EIAR
SARC/OARI
KARC /EIAR
KARC /EIAR
KARC /EIAR
KARC /EIAR
SRARC/ARARI
KARC /EIAR
KARC /EIAR
ADARC/ARARI
ADARC/ARARI
DBARC/ARARI
SRARC/ARARI
HARC/EIAR
SRARC/ARARI
ADARC/ARARI
DBARC/ARARI
KARC /EIAR
Sulla
2007
85-95
130
800-1500
1800-2600
30-60
*Varieties recommended for production at present time by the National Wheat Research Project.
35
AwARC/SARI
Table 2.4: Agronomic characteristics and recommended production domains of released durum wheat varieties
Variety
Plant ht.
(cm)
120
120
115
110
Maturity (days)
Rainfall (mm)
Boohai
Foka
Kilinto
Bichena
Year of
release
1982
1993
1994
1995
500-1200
400-1200
800-1200
Altitude
(m)
1800-2400
1800-2700
1600-2700
1900-2500
Yield
(q/ha)
35-45
30-40
20-45
20-30
Breeder/
Maintainer
DZARC/EIAR
DZARC/EIAR
DZARC/EIAR
DZARC/EIAR
125
105-154
100-140
130-150
Quami
1996
115
100-120
400-1200
1600-2200
20-40
DZARC/EIAR
Asasa
1997
116
110-130
400-1200
1680-2400
25-40
DZARC/EIAR
Robe
1999
106
120-140
800-1200
2000-2500
30-35
DZARC/EIAR
Ginchi
2000
-
-
800-1200
2000-2300
30-50
DZARC/EIAR
Yerer
Ude
Laste
Lelisso
2002
2002
2002
2002
-
-
-
-
800-1200
800-1200
400-950
2000-2300
1800-2400
2300-2800
30-50
30-50
27
32.78
DZARC/EIAR
DZARC/EIAR
SRARC/ARARI
SARC/OARI
Illani
2004
96
135
750-1000
2300-2600
35-55
SARC/OARI
Megenagna
2004
109-120
102-132
>700
1900-2800
20-40
ADARC/ARARI
Oda
2004
110
137
750-1000
2300-2600
38-53
SARC/OARI
Mettaya
2004
97-125
113-139
>600
2000-2800
21-35
ADARC/ARARI
Mosobo
2004
100-110
102-132
>700
1900-2800
20-40
ADARC/ARARI
Selam
2004
81-103
107-135
>700
1900-2800
22-36
ADARC/ARARI
Ejersa
2005
82
134
750-1000
2300-2600
62
SARC/OARI
Bakalcha
2005
81
133
750-1000
2300-2600
67
SARC/OARI
Malefia
2005
79-84
139
900-1200
2400-3000
27.12
SRARC/ARARI
Kokate
2005
95-110
110-120
>700
1900-2800
30.5
AwARC/SARI
Obsa
Flakit
2006
2007
82
42-76
131
140
900-1200
900-1200
2300-2600
2400-3000
68
21-35
SARC/OARI
SRARC/ARARI
Sorghum production
Sorghum [Sorghum bicolor (L.) Moench] is one of the most important cereal crops and is the dietary
staple of the farming community in Ethiopia. It is grown on 1.6 m ha in the country. Amahara,
Oromia, and Tigray regions are the major producers. Grain is mostly for food purpose, consumed in
the form of flat breads (‘injera’) and porridges (thick or thin or ‘gonfo’); stover is an important source
of dry season maintenance rations for livestock; as fuel, and construction material, especially in
lowland areas. Sweet sorghum is emerging as a feedstock for ethanol production. Generally, it gives
food/feed, fodder and fuel, without significant trade-offs in any of these uses in a production cycle.
Adaptation
Grain sorghum is adapted to be grown on many different environmental conditions throughout
Ethiopia. Many farmers in Ethiopia have found the drought tolerance of grain sorghum makes it an
attractive alternative to maize. By virtue of the short growing season, wide adaptation, and versatile
planting date of grain sorghum, some producers also recognize the ease of fitting this crop into
intercrop systems with maize, haricot beans, and other crops. Although it will produce best on deep,
fertile, well-drained loamy soils, it is much more tolerant of shallow soil and droughty conditions than
maize. It can be grown successfully on clay, clay loam, or sandy loam soils. However, don't expect
soils that produce poor haricot beans or poor maize crops to yield a bumper crop of grain sorghum.
The best soils for other crops also produce the highest grain sorghum yields. It tolerates a pH ranging
36
from 5.5 to 8.5 and some degrees of salinity, alkalinity, and poor drainage. In Ethiopia, sorghum
grows in 13 of the 18 major agro-ecological zones and in 41 of the 49 sub-agro-ecological zones. The
national average yield is 12 q/ha. However, research results indicate that 30–60 q/ha can be produced based on
the growing environment. The major constraints for the low national average yield are attributed to drought,
Striga, birds, low soil fertility, diseases and insect pests.
Cultivars Released
Over the years, a large number of cultivars have been released (Table 2,5) based on the national and
regional research institutions-bred improved germplasm in all adaptation environments (low,
intermediate and high). The number of cultivars released were highest in low (Table1) followed by
intermediate sorghum growing environments. While released cultivars include both hybrids and
varieties in the country, it is mostly varieties that were released in most parts of the country (the
exception being one hybrid currently released for the moisture stress areas of the country). The
cultivars’ yields potential vary from place to place. The yield potential of highland, intermediate and
lowland sorghum cultivars are about 65, 69, and 45 quintals per hectare, respectively.
Hybrid Selection
Various hybrids perform differently in different parts of Ethiopia. Therefore, it is important to select
hybrids which have performed well in variety trials. Based on performance test, currently one
sorghum hybrid (P-9501A X ICSR-14) has been released for commercial production for moisture
stress areas of the country. Early maturing hybrids of 85- to 90-day relative maturity are
recommended. Hybrid choices exist but selection currently is limited for lowland and moisture stress
areas production. Besides maturity and yield potential, also consider seedling vigor, plant height,
lodging resistance, stress and disease tolerance, susceptibility to lodging, head exertion; panicle type
or head compactness, test weight, and seed quality (including tannin levels). Low tannin levels are
desirable.
Crop Management
Along with variety development activities, crop agronomy or management activities have been
conducted by the national and regional programs. As a result, plant and row spacing, seed and
fertilizer rate, planting date (Table 2.5) frequency of plowing and weeding recommendations for
various agro-ecologies have been devised.
Land Preparation and Planting Dates
Land preparation is the primary prerequisite for sorghum production. It must be done with maximum
care, because the crop must be given appropriate seedbed to guarantee uniform emergence and stand
establishment. It includes clearing, plowing, harrowing, ridge, and row making. Removing and
burning of sorghum and maize stubbles are very important to avoid pests and diseases that may over
winter in them and carryover to the new crop. It needs a warm, moist soil well supplied with air and
fine enough to provide good seed-soil contact for rapid germination and establishment. Poor
emergence and seedling growth may result if grain sorghum is planted in poor seedbed. Slow seedling
growth may increase losses due to weed competition, diseases, insects, and herbicide damage. An
ideal seedbed should accomplish good tillage practices such as control weeds, conserve moisture,
preserve or improve tilth, control wind and soil erosion, and be suitable for planting and cultivating
with available equipment. Fertile, well drained soils are important to optimize yield. Although
frequency of plowing is decided by workability of the soil, rainfall, and other economic situations,
two to three times plowing is sufficient.
In the dry areas, primarily, on light soils, moisture conservation, and wind erosion controls are
essential. Tied-ridges (furrow dams), have been widely used in the African semi-arid tropics as in situ
37
soil and water conservation systems. If the tied-ridges are made before the first heavy rains, they
conserve the early rainfall, and allow it to infiltrate, which thus benefits crop growth. Using tiedridges instead of flat seedbed (farmers’ practice) in dry crop seasons, significantly increased sorghum
grain yield.
Seeding rates
Seeding rate and row spacing are shown in Table 2.5. Seeding in rows and broadcasting are the two
common planting methods of sorghum. Because of its relatively short growing season, grain sorghum
is often planted in lowland areas in mid-June or even in early July. Such late planting may be
unavoidable in case there may be late onset of rainfall situations, but earlier planting usually results in
higher yields and should be practiced when possible. When planting into a good seedbed, expect
about 85 percent of the sorghum seed to produce normal and mature plants. The optimum population
for high yields under good growing conditions will usually be about 88,888 plants per hectare. Under
irrigation or high levels of management on highly productive soils, this population is recommended.
A population of 88,888 plants per hectare will usually require around 8-10 kg of seed. But the weight
of seed planted is not a good measure of population since seed size varies considerably among various
varieties or hybrids. The seed spacing required for 88,888 plants per hectare row widths are 15 to
20cm between plants and 75cm between rows. Row spacing studies have indicated that grain sorghum
yields will generally be higher with narrow (75 cm or less) rows if other growing conditions are good.
You must control weeds, however, to realize such benefits. When cultivation is to be used for weed
control, the row width will be limited by the cultivation equipment. Where weed control practices and
equipment will allow, row widths of 60 to 75 centimeters between rows are preferred. Thinning can
be conducted 15 days after seedling emergence to maintain the optimum population.
Stand establishment
Plant establishment for sorghum is slower and generally more challenging compared to wheat or
maize. Shoots won’t emerge if the seed is placed too deeply and seedlings are not as vigorous as
maize. Root system development progresses more rapidly than above-ground growth during about
the first month of plant establishment, providing the appearance of abnormal plant development. The
seeding depth ranges from 3 to 4 cm. Plant at shallow depths in fine textured soils and deeper in
coarse -textured soils.
Fertility
The fertilization of grain sorghum should be based on soil test recommendations. One of the most
important points to remember is that grain sorghum is not tolerant of soil acidity. When the soil pH is
lower than 5.8, sorghum yields will usually be extremely low. If the soil pH of your field is lower than
5.8, you should lime to bring it up to 6.5 before planting grain sorghum. Recommendations made by
the different research institutions are shown in Table 25. Applying nitrogen is essential for acceptable
yields. Under good growing conditions, grain sorghum should receive 50 to 100 kg of nitrogen per
hectare. Then apply a nitrogen side dressing when the plants reach a height of about knee high.
Rotating sorghum with legume crops (haricot beans, cowpeas) improves yield as legumes can fix
nitrogen, leading to improving the fertility status of the soil Profitable crop response to applied
fertilizer depends on soil water availability. Integration of tied-ridging for water conservation with
nutrient management results in increased sorghum yields in semi-arid Ethiopia. Tied-ridging before or
with the onset of rainfall is more effective than the traditional practice of shilshalo. Improved water
availability during grain fill is a major concern. Water conservation with tied-ridging found to reduce
water deficits during grain fill.
Fertilizer use is not likely to be economical unless stress due to water deficits can be reduced with soil
moisture retention technique like to tied-ridging.
38
Table 2.5. Cultivars released, altitude, growing period (days), sowing date, seed rate (kg/ha), fertilizer rate (kg/ha), and row spacing (cm) and research
centers of the breeders for different sorghum producing areas
Cultivars released for
different environments
HIGHLAND SORGHUM
Chiro, Chelenko ETS2752,
AL-70
Muyra-1 Muyra-2
INTERMEDIATE
SORGHUM
Geremew , Baji, Birmash,
IS9302, Emahoy
Lalo, Dano,
Aba-Melko
Altitude
(m)
1900 to 2700
1600 to1900
700 to 1680
1500 to 900
1600 to1900
Growing
period
175 to
210
150 to
180
Sowing date
15 April to
10 May
Seed rate
8-10
for row planting
10-15 broadcast
1 to 15 May
8-10
for row planting
10-15 broadcast
fertilizer rate
row spacing
Urea
DAP
Between
rows
Between
plants
100
100
75
20
100
100
100
100
100
75
75
75
75
75
15
15
15
15
100
LOWLAND SORGHUM
Teshale, Gubiye Abshir,
15
75
100
50
8-10
Mid June to
90 to 130
<1600
Meko Seredo, 76T#23,
for row planting
early July
Gambella1107 WSV-387,
10-15 broadcast
Macia*, Red Swazi*,
5-10 for row & 15Gido, Raya, Miskir. Grana-1,
20
Mid-July
122 to
1450 to 1850
Hormat, Abuare, Birhan,
75
100
50
broad cast
129
Yeju
Note: *- The two malt sorghum varieties, MARC-Melkassa Agric. Research Center, EIAR- Ethiopian Institute of Agric. Research, PARCPawee Agric. Research Center, BRC- Bako Agric. Research Center, OARI- Oromia Agric. Research Institute, JARC- Jimma Agric.
Research Center, SRARC-Sirinka Agric. Research Center, ARARI- Amahara Regional Agric. Research Institute (Centers responsible to give
breeder seeds)
Weed control
Weed problems in grain sorghum include perennial grasses such as Johnsongrass and Bermuda grass,
annual grasses such as setaria species and broadleaf weeds such as field bind and amaranthus.
Broadleaf weeds and many annual grasses are generally controlled by pre-emergence and early postemergence herbicide applications. Perennial grasses and some annual grasses are not well controlled
by herbicides available for use in grain sorghum. Mechanical weed control options include: pre-plant,
pre-emergence (before coleoptile near the soil surface) or post-emergence (crop emergence to 15cm
tall) with a light, spring-tooth harrow or rotary hoe, and between-row tillage for wide-rowed grain
sorghum. Tillage for seedbed preparation followed by shallow cultivation just prior to planting will
control initial weed populations and provide the opportunity to establish sorghum ahead of lateremerging weeds. Sorghum is a poor competitor with weeds during stand establishment. Good
seedbed preparation, early cultivation, and narrow rows can help prevent the weeds. An effective
weed control program for grain sorghum will include the following practices: (1) identification of the
problem weeds; (2) selection of the correct herbicides; (3) use of the correct rate and application
method for the herbicides; (4) good seedbed preparation; (5) use of cultivation for control when
needed; and (6) use of good production practices. Herbicides can be used to allow adequate crop
establishment. Herbicide options include: Pre-plant incorporated = atrazine, and Lasso;
Pre-emergence = atrazine, and Lasso; Post-emergence = atrazine + oil, and 2- 4-D.
Insects and their control
Potential insect problems include stalk borers, sorghum shoot flies, sorghum chaffers, sorghum midge
weevils, green bugs and grasshoppers. Select cultivars/hybrids with insect tolerance. Economic
thresholds and foliar insecticides are available for green bug management in grain sorghum. Several
insecticides also are available for grasshopper control. Birds may be a threat as grain nears
maturity. Several insects may attack grain sorghum in sorghum growing areas, and their control may
be necessary if you are to have profitable yields. The extent of damage by insects in grain sorghum is
39
often related to the planting date. When sorghum is planted late, more severe insect problems are
likely to occur. Early planting often helps prevent severe insect damage.
Insects may attack grain sorghum from the seedling stage through maturity and even in storage. In
addition to early planting, control practices include the use of recommended insecticides when
damaging populations of insects are detected.
During the flowering period, examine plants frequently in the cool hours of the morning for signs of
midge populations. Midge problems tend to be more frequent for late plantings or if Johnson grass is
present where grain sorghum is growing. This pest is very common in north Shoa, Pawee and
Gambella. So early planting minimizes the damage due to midge.
Managing diseases of grain sorghum
Seed and seedling rots may be prevented with high-quality, fungicide-treated seed. Choose
cultivars/hybrids with good seedling vigor, adequate stalk strength and tolerance to head smuts,
Anthracnose, Fusarium (head blight), and charcoal rot. Periods of high humidity and warm air
temperatures may cause some reddish or purple leaf streaking or spotting, but the problem is not
considered a serious threat to grain yield. Use hybrid selection, high-quality seed, resistant varieties,
proper crop rotation, and other cultural practices to minimize disease potential. As pathogens are
seed-born, both covered and loose smuts can be controlled by soaking the seed for 20 minutes into
cow or goat urine that has been preserved for a week. Alternatively, the seed can be dressed with
chemicals such as Thriam at 1:400 and Apron plus. To avoid later infection by loose smut, the
smutted heads must be removed as soon as they are seen in the field. Anthracnose is the most
damaging leaf disease of grain sorghum in mid and high-altitude areas of Ethiopia. Serious losses
have also been associated with Fusarium head blight and charcoal rot. Anthracnose and grain mold
develop as grain sorghum approaches maturity. Apparently, grain sorghum is susceptible to attack by
these fungi after the seed head emerges from the boot until maturity. Frequent showers from head
exertion through grain fill favor rapid blighting of the leaves and seed head. Disease-resistant varieties
(IS158, IS2230, NES8827 and NES8835) are the most efficient and inexpensive means of controlling
anthracnose. Most adapted grain sorghum varieties had good disease resistance. Early planting and
rotation of grain sorghum with non-host crops of the anthracnose fungus may also help minimize
disease-related yield losses.
Good crop management practices such as crop rotation and balanced fertility are the best defense
against head blight. Harvesting grain sorghum at 17-to 20-percent moisture may minimize head blight
damage.
Charcoal rot develops primarily on maturing grain sorghum under severe moisture stress. High plant
populations, which reduce the drought tolerance of grain sorghum, are also known to contribute to
charcoal rot damage. Extensive lodging is largely responsible for yield loses related to charcoal rot.
Most adapted grain sorghum varieties are tolerant to charcoal rot except under conditions of severe
drought stress. Following recommended seeding rates, fertility levels, and conducing timely
harvesting to avoid losses due to lodging should reduce disease losses. Crop rotation is largely
ineffective for controlling this disease due to the wide field crop host range of the charcoal rot fungus.
Harvesting and storage
Grain sorghum remains green and the seed retain moisture for a long period of time, even after the
seed are mature. For this reason, harvest the grain at 18- to 23-percent moisture and artificially dry it
rather than field drying it. Field drying grain sorghum is likely to result in excessive harvest losses as
well as high losses to birds, insects, lodging, and perhaps from sprouting of grain in the heads during
prolonged periods of wet weather. For safe storage over long periods, grain sorghum should have no
more than 12-percent moisture. To control pests in the store: Safeguarding of sanitation and hygiene
of storage/’gottera’, use of both preventive and protective chemicals (Actellic 2% D and Malathion
40
5% D at 50 g/q), fumigation of storage with chemicals such as phostoxin, quickphox and others, use
of improved storage structures (sealed and elevated with rodent baffles)
Witch weeds (Striga species)
Witch weeds are becoming the major threats against sorghum production. The two most common
ones are Striga hermonthiica and Striga asiatica. Striga plants have beautiful purple (S. hermonthiica)
and red (S. asiatica) flowers. They are semi-parasitic plants. These plants attach their haustoria under
the ground to the sorghum root system and take out all nutrients from it.
Symptoms: The leaves of the host plants will be changed into yellow (chlorosis). Then, they show
stunted growth and gradually die. Striga plants begin to emerge in about 30 days after the emergence
of sorghum.
Control: Using resistant varieties such as Gubiye, Abshir, Emahoy and Birhan, that is host plant
resistance, is the best option of controlling Striga infestation. The following mechanisms of host plant
resistance have been known so far: low germination stimulant production, using mechanical barriers,
inhibiting germ tube exoenzymes by root exudates, phytoalexine synthesis, post attachment
hypersensitive reactions or incompatibility, antibiosis, insensitivity to Striga toxin, and avoidance
through root growth habit. Gubiye and Abshir are varieties resistant to Striga due to low germination
stimulant production. Birhan is another resistant variety released by the Sirinka Agricultural Research
Center for Welo area, and it combines about three mechanisms of resistance.
Rotation of sorghum with non-susceptible legumes is another option. Although most of the damage by
Striga takes place under ground before the emergence of the striga plants, hand pulling of the
emerged plants is still the most feasible controlling approach for the small-scale subsistence farmers.
Usually, Striga, infestation is very high if sorghum is grown on poor soils. Therefore, the use of a
relatively higher dose of nitrogen fertilizers reduces its infestation significantly. Trap crops exude
Striga seed germination stimulant but they are not parasitized because of dead Striga seedlings.
Although chemical control is not feasible, target spray of 2-4-D can be used to control it. An
integrated approach containing the use of resistant varieties, hand weeding before flower initiation,
cultural practices that conserve soil moisture and nutrient, chemical inputs (herbicides and fertilizers)
are the best approach to control Striga.
2.2. Pulses
Pulses are the second important crops in terms of both acreage and production next to cereals in
Ethiopia. Mostly subsistence farmers under rain-fed conditions grow them. Highland pulses (faba
bean, field pea, chickpea, and lentil) have the largest share of area and total national production of all
pulses grown in Ethiopia. They are valuable and cheap sources of protein when consumed with
cereals, which are deficient in essential amino acids. Pulses play significant roles in soil fertility
restoration and in export market. Despite their importance, however, production and productivity are
far below the potentials due to several factors including the insufficient supply of seeds of improved
varieties. A number of improved varieties of highland pulses have been released for the last two
decades. The current Extension Package Program at the national level made farmers aware of the
importance of improved seeds of various crops. Despite all these, seeds of improved varieties are not
yet sufficiently made available to the needy farmers. It is believed that more varieties will be released
from research and the demand for high quality seed is expected to increase because more farmers will
realize the benefits of the use of quality seeds. In Ethiopia, where the use of improved crop production
technologies in general and improved seeds in particular is limited, the lack of technical skill is one of
the most important limiting factors in seed production. Young breeders, seed technologists, farm
41
management units of research centers, extension workers assisting progressive farmers in seed
production, private seed producers and trainers hardly find suitable guide and appropriate source
material to seed maintenance and production. It is believed that this technical manual will fill this gap.
Agro-ecologies for Highland Pulses
Faba bean grows on clay, silt or heavy deep, fertile and well-drained soils with adequate reserves of
organic matter and a PH range of 6.0-7.0 for high seed yield. Field pea grows on a wide range of soil
types with a reasonable fertility levels and PH range of 5.5-6.5. Both crops require an altitude range of
1800-3000 meters above sea level and annual rainfall of 700-1000mm under the Ethiopian condition.
On the other hand, chickpea and lentil are grown mostly on clay soils with neutral to alkaline PH on
residual moisture. They require altitudes of 1700-2400 meters above sea level in Ethiopia. Not all
crops tolerate waterlogging.
Faba Bean
Among major production constraints is the inherently low grain yielding potentials of the indigenous
cultivars including susceptibility to biotic and abiotic stresses. Faba bean production is also limited by
diseases. Economically important diseases of faba bean in Ethiopia are chocolate spot (Botrytis
fabae), rust (Uromyces viciae-fabae) and root rot (Fusarium solani). Few insects are also affecting
faba bean production. The most important ones are African bollworm (Helicoverpa armigera) and
bean bruchids (Callosobruchus chinensis). Both broad-leaved and grass weed species cause
significant yield losses. Waterlogging, frost and moisture stress are the major abiotic stresses.
Drainage of excess water under waterlogged Vertisols using broad bed and furrow (BBF) in Ethiopia
resulted in a moderate control to black root rot and in a dramatic yield increment compared to
production under flatbeds. Poor fertility, low pH, or acidity, shallow soils are the major soil related
problems. Use of poor cultural practices (marginal lands, minimum tillage, low seed rates, inadequate
or no weeding, no fertilizers also contributes to low productivity of the crop.
Improved varieties
So far, 17 faba bean varieties have been released and are suitable for the typical highlands (2300-3000
masl), mid-altitude (1900-2300 masl.), and waterlogged Vertisols. Large seeded ones are suitable for
export market because of their larger seed size, while the remaining are for local consumption. List of
improved varieties of faba bean recommended for wider and/or specific adaptation is given in the
Table 2.6.
42
Table 2.6. Improved varieties of faba bean, their character and adaptation areas Variety
CS20DK
NC58
KUSE 2-27-33
Kasa
Bulga 70
Mesay
Tesfa
Holeta-2
Degaga
Moti
Gebelcho
Obse
Wayu
Salale
Walki
Adethana (Adet)
Dagim (Sheno)
Lalo (Sheno)
Yield (kg/ha)
On station
On farm
2.0-4.0
1.5-3.0
2.0-4.0
1.5-3.5
2.0-3.5
1.5-2.5
4.5-5.5
2.5-4.0
2.0-4.5
1.5-3.5
2.5-5.0
2.0-3.5
2.0-4.0
1.5-3.5
2.0-5.0
1.5-3.5
2.5-5.0
2.0-4.5
2.8-5.1
2.3-3.5
2.5-4.4
2.0-3.0
2.5-6.1
2.1-3.5
2.2-3.3
1.0-2.3
1.8-3.2
1.0-2.3
2.4-5.2
2.0-4.2
1.5-3.9
1.8-4.2
3.5
3.6
1000 seed
Wt (g)
476
449
393
428
440
428
441
517
781
797
821
346
312
676
520
299
325
Crude protein
content (%)
25.0
27
25.4
28
27.0
27.0
27.02
25.73
29.16
27.0
26.5
26.91
26.47
28.21
27.48
Suitable
altitudel (m)
2300-3000
1900-2300
2300-3000
1900-2300
2300-3000
1800-2300
1800-2300
2300-3000
1800-3000
1800-3000
1800-3000
1800-3000
2100-2700
2100-2700
1800-2800
2240-2630
2600-3000
2600-3000
Cultural practices
Appropriate fertilizer and seed rates, tillage frequency, planting date and plant population density
have been developed for the major production areas (Table 2.7). The weed flora associated with faba
bean and field pea has been identified. Estimated yield losses due to weed competition, critical weed
free periods optimum periods and frequency of hand weeding and weed control using chemical
methods have been developed and recommended for the major weeds.
Table 2.7. Agronomic practices recommended for faba bean production
Agronomic practices
Recommendation
Land preparation
Two ploughing before planting
Sowing date
Mid June to early July
Seed rate (kg/ha)
Row planting
40 between rows & 5 between plant
Broad
casting
150-200
Fertilizer rate
100 DAP ha-1 where necessary or on acidic Nitosol 4t of farmyard
manure with 26 kg of P ha-1
Drainage of waterlogged Vertisols
Alternate broad bed of 80 cm with furrow of 20 cm on either sides
Weed control
•
One to twice hand weeding (25-30 DAE & 40-45 DAE)*
•
•
•
Post emergence application of Fluazifobuthyl or
Fusilade 250 g/l EC at the rate 0.25 kg a.i. ha-1
Use of clean seeds
* DAE = days after emergence
Pest Management
Major diseases and insects in the major production areas have been identified. Major diseases include
chocolate spot (Botrytis fabae), rust (Uromyces viciae-fabae) and black root rot (Fusarium solani) for
faba bean. Pod borer (Helicoverpa armigera) and bean bruchids (Callosobruchus chinensis) are
important insects. Genetic resistance to chocolate spot and black root rot in faba bean has been
43
identified. Fungicides for the control of the major diseases and insecticide for the major insects have
also been recommended (see Tables 2.8 and 2.9).
Table 2.8. Major diseases of faba bean in Ethiopia and recommended control measures
Major diseases
Chocolate spot (Botrytis fabae)
Rust (Uromyces viciae-fabae)
Black root rot (Fusarium solani)
Control measures
Resistant varieties
Foliar application of Chlorotholonil at the rate of 2.5kg ha-1 a.i every 10
days when infection reaches 30% or Mancozeb at the rate of 3kg ha-1
a.i. every week at the same thresh hold level.
Crop rotation and debris management
Resistant varieties
Spraying Mancozeb at the rate of 2.5kg ha-1 a.i. weekly when infection
reaches 5%.
Drainage using broad bed and furrows (BBF) and Camber beds
Resistant varieties
Table 2.9. Major insects of faba bean in Ethiopia and recommended control measures
Common name
African bollworm
(Helicoverpa armigera)
Bean Bruchids (Callosobruchus chinensis)
Control methods
Single spray with Cypermethrin at the rate of 150g a.i. ha-1
or Endosulfan 39% EC 2 lt ha-1 when infestation starts
Application of Primiphos-methyl at the rate of 40g/100kg
(6-8 ppm)
Harvest and post-harvest handling
The plants of faba bean are physiologically mature and ready for harvest in 4-5 months after sowing
depending on the cultivars and the environment. In the cool and higher altitudes, it tends mature
longer while in the warmer mid-altitude areas it matures. Harvesting could be done mechanically or
manually. In developed countries, it is harvested by combining machines. In tropical Africa, including
Ethiopia, manual harvesting is the common practice. Traditionally, the plants are hand-pulled or cut
by small knife and sickles. Harvesting is done before the plants are fully dry after physiological
maturity as late harvesting may result in shedding, shattering, or rotting of pods if untimely rain is
encountered. The appropriate stage is when the leaves and the pods dry out and when the grain
moisture content is significantly reduced (about 16-18%). Harvesting is usually done early in the
morning or late afternoon to reduce losses due to shattering. Time of harvesting more or less exactly
coincides with the start of the dry season in most parts of tropical Africa and it is easily possible to
achieve low moisture contents while the crop is still in the field. The pulled or cut plants are gathered
into small heaps and left in the field for a few days to dry. They are then transported to the threshing
ground by human labor or by animal pulled carts. Threshing is traditionally done by beating the plants
by sticks or by trampling animals on the plants. Storage is a major problem because of damages
incurred by storage pests like bruchids (Callosobruchus spp). Seeds need to be carefully inspected
before storing and storage structures need be cleaned, or if possible, fumigated. Under a required
moisture content of 11-14%, seeds of faba bean maybe stored for 2-7 years at temperatures of 5-10 °C
and for 1-4 years at 10-20 °C. Then grain should be stored in dry and cool places free of pests and
somehow be protected from absorbing moisture in the surrounding.
Field pea
The use of inherently low yielding local field pea cultivars and suboptimal cultural practices
(allocation of marginal lands, poor seedbed preparation, low seed rates, inadequate or no weeding,
44
poor nutrient management) are the major factors for low productivity of the crop in the country.
Diseases, (Ascochyta blight/spot caused by Mycosphaerella pinodes, powdery mildew caused by
Erysiphe polygoni.), insect pests such as green pea aphid (Acrythosiphon pisum), African bollworm
(Helocoverpa agmigera) and bruchids (Callosobruchus chinensis) cause significant yield losses each
year. Weeds also cause substantial losses to field pea production unless rigorously controlled during
critical period of competition. The critical period of weed competition may vary from 3 to 8 weeks
after crop emergence. Both broad leaved and annual and perennial grasses affect field pea. Field pea
weeds can be best controlled with hand weeding. The critical period of weeding are presented in
Table ... Besides the biotic stresses mentioned above, the abiotic stresses such as waterlogging, frost
and moisture stress, soil environment (poor fertility, low pH or acidity, shallowness) are also
important production constraints.
Improved varieties
So far, 23 field pea varieties have been nationally or regionally released for different agro-ecological
zones of the country (Table 2.10.).
Cultural practices
Appropriate fertilizer and seed rates, tillage frequency, planting date and plant population densities
have been developed for the major production areas. The weed flora associated with field pea has
been identified. Estimated yield losses due to weed competition, critical weed free periods optimum
periods and frequency of hand weeding and weed control using chemical methods have been
developed and recommended for the major weeds (Table 2.11.).
Pest management
Major diseases and insects in the major production areas have been identified. Major diseases include
Ascochyta blight/spot (Mycosphaerella pinodes) and powdery mildew (Erysiphe polygoni). Aphids
(Acrythosiphon pisum), pod borer (Helicoverpa armigera) and bean bruchids (Callosobruchus
chinensis) are important insects. Genetic resistance to the diseases and insects have not been identified
though the released varieties have some level of tolerance that the local landraces. Fungicides for the
control of the major diseases and insecticide for the major insects have also been recommended
(Tables 2.12 and 2.13.).
Harvest and post-harvest handling
Field pea is harvested when the seeds are physiologically matured. Under Ethiopian condition, this
period is reached within 115-150 days after sowing depending on the variety and environment.
Harvesting is usually done by manual labor using simple sickles. Since field pea has an indeterminate
growth habit in nature, some pods in the upper portion of the plant could be green when the majority
of the pods at the lower portion of the plant reached physiological maturity. Therefore, the freshly cut
crops should be left on the ground to well dried (may be for three to four weeks) before threshing.
Late harvesting of field pea may result in shedding and rotting of pods if untimely rain is encountered
and in shattering of the seeds. Therefore, harvesting should be done at the appropriate stages when the
leaves and the pods dry out and when the grain moisture content is significantly reduced (16-18%).
Harvesting is usually done in early morning or late afternoon to reduce losses. Threshing field pea is
done by trampling with animals or by hand biting. If available, stationary mechanical threshers
powered by tractor could be used in large-scale production when manual labor is relatively expensive. High seed moisture content in storage has adverse effect on quality and viability. The initial grain
moisture content of field pea must be reduced to the required level of nearly 12% before storage.
Optimum moisture content reduces the deterioration rates during storage, prevents, or reduces attack
45
by moulds and insects. Then grain should be stored in dry and cool places free of pests and somehow
be protected from absorbing moisture from the surrounding.
Table 2.10. Released field pea varieties with their agronomic and morphological characteristics
Variety
Yield (t/ha)
On station On farm
FP.ex.DZ
Mohanderfer
G22763-2C
NC 95 Haik
Tegegnech
Markos
Adi
Milky
Hasabie
Holeta
Walmera
Megeri
Gume
Tulu-shenen (Sin)
Dadimos (Sinana)
Hursa (Sinana)
Adet-1 (Adet)
Sefinesh (Adet)
Weyitu (Sinana)
Tulu-dimtu (Sina)
Bamo (Sinana)
Arjo-1 (Bako)
Bariso (Bako)
2.0-3.0
2.0-3.0
2.0-3.5
2.0-3.0
2.5-3.5
2.5-3.5
2.5-4.0
2.5-3.5
2.0-3.0
2.0-4.0
2.5-4.0
2.1-4.1
2.0-4.1
1.0-1.5
1.0-1.5
1.5-2.0
1.5-2.0
1.5-3.0
1.5-2.5
2.0-3.0
1.5-3.0
1.5-2.0
2.0-3.0
2.0-3.0
1.0-3.4
1.6-3.3
Seed color
(at harvest)
White
White
White
Light brown
Cream*
Cream*
White
White
Light brown
Light brown
White
Green
Cream*
1000 seed
Wt(g)
156
223
145
163
215
188
209
157
132
143
174
136
201
Crude protein
content
(%)
22.0
25.1
22.2
23.77
26.8
23.0
22.0
26.6
23.0
23.1
27.0
25.0
Suitable
altitude
(m)
1800-2300
1800-3000
2000-3000
2300-3000
2000-3000
1800-2300
2300-3000
2300-3000
1800-2300
2300-3000
2300-3000
1800-2400
1800-3000
Cream*
2.6
2.5
-
4.4
2.5-3.9
2.5-3.9
2.8
2.0-2.5
2.0-2.5
1800-3000
1800-3000
white
white
white
174
250-300
200-250
1800-2600
2000-2600
2000-2600
* Black helium Table 2.11.. Agronomic practices recommended for field pea production
Agronomic practices
Land preparation
Sowing date
Row planting
Seed rate (kg/ha)
Broad casting
Fertilizer rate
Weed control
* DAE = days after emergence
Recommendation
Two ploughing before planting
Mid June to early July
75-150
50-100 DAP ha-1 where necessary
Once hand weeding (25-30 DAE)
Post emergence application of Fluazifobuthyl
or Fusilade 250 g/l EC at the rate 0.25 kg a.i. ha-1
Use of clean seeds
Table 2.12. Major diseases of field pea in Ethiopia and their control methods
Major diseases
Ascochyta blight
(Ascochyta pisi)
Powdery mildew
(Erysiphe polygoni)
Control methods
Improved (tolerant) varieties
Improved (tolerant) varieties with crop
rotation and debris management
46
Table 2.13. Major insects of field pea in Ethiopia and their control methods
Common name
Pea
aphid
(Acyrthosiphon
pisum)
African bollworm
(Helicoverpa armigera)
Control methods
Pirimor 50%WP at the rate of 0.5 kg a.i. ha-1,
Pericarp 5% WP 1kg ha-1 or Dimethoale 4% 1lt
ha-1 when 35% of the plants are infested
Single spray with Cypermethrin at the rate of 150g
a.i. ha-1 or Endosulfan 39% EC 2 lt ha-1 when
infestation starts
Chickpea
Chickpea is a good source of dietary protein, fertility restorer through symbiotic nitrogen fixation,
drought tolerant and break crop. It can be processed and used in form of dehulled (split seed or kik),
and soaked and roasted (kolo or snacks). The crop can be used in mixture with cereals and root crops
in the preparation of childhood food such as faffa, of which 10% is chickpea, as a protein
supplements. The yield potential of chickpea is as high as 6 t/ha and even in Ethiopia realized
potential closer to this often obtained under research conditions. However, the national average grain
yield in Ethiopia has remained extremely low, usually 0.6-0.8t/ha, owing to different biological and
physical constraints. The major ones are inherently low grain-yielding potentials of indigenous
chickpea cultivars including susceptibility to biotic and a biotic stresses, poor crop management and
cultural practices followed by growers biotic and abiotic stresses.
Chickpea varieties
The characteristics of improved chickpea varieties recommended for production are given in Table
2.14.
Cultural practices
Seedbed preparation
To keep the soil friable and weed free, it is advisable to plough deep once from March to May in dry
season and disking twice from Mid June to early August. Where chickpea is grown on flat heavy clay
soils, it is advisable to use ridge and furrow (RF) plots as it facilitate the removal of excess water from
the field. Broad bed and furrow (BBF) can also be used on gentle slopes of 0-0.8%.
Sowing time and methods
Planting time is an important factor in increasing chickpea yield. The recommended sowing times for
chickpea vary with altitudes, locations, and depends upon site-specific seasonal rainfall, soil types,
and maturity period of specific chickpea variety. The recommended sowing date for Vertisols of
medium and high altitude areas is from mid August to early September depending up on the intensity
of rainfall. Advancing planting time to early September increase about 50% yield in chickpea since
planting during this rainy season allows the crop to grow vigorously and enable it to make efficient
use of conserved moisture during germination, establishment and seed filling stage. In low moisture
stressed environments such as low lands or sandy soils, early planting in July is advantageous.
Chickpea can be sown in rows or broadcasted. Planting in row gave higher yields as compared with
broadcast method as the former facilitates inter-row cultivation and hand weeding.
47
Seed rate
The optimum planting density for chickpea varies from location to location depending up on the
growing environments and growth habit of the crop. It was known that seeding rate has no significant
effects on seed yield due to the capacity of the crop to produce large number of branches to
compensate for low plant population. However, it is essential to use high seed rate in ensuring good
plant stand under adverse environmental conditions. For row planting, a spacing of 30cm between
rows and 10cm between plants is recommended (i.e. a density of about 333,334 plants/ha). A reduced
spacing between plants can be used for varieties with erect and hence plant density can be increased.
However, seed rate for broadcast method appears to vary depending up on the seed size of the
cultivars and growth habit. So, high seed rates for large seeded and erect cultivars and low seed rates
for varieties with small seed size and prostrate growth habit can be used. For instance , the seeding
rates for small seeded cultivars such as DZ-10-4 and DZ-10-11 varies is 90-100 kg/ha where as that of
large seeded cultivars like Shasho, Arerti and Mariye vary up to 140-160 kg/ha ( Table 2.14.).
Table 2.14.. Improved chickpea varieties, their agronomic characters and adaptation areas
Variety
Day to
maturity
Growth habit
DZ-10-4
111-135
Semi-erect
DZ-10-11
106-123
Dubie
Mariye
Wroku
Akaki
Arerti
Shasho
Habru
Chefe
Natoli
Teji
Ejere
Seed color
White
100
Seed
wt (g)
10.2
Early September
Seed
rate
(kg/ha)
65-75
Adaptation zone
Altitude
Rain fall
(mm)
(m)
1800-2300
700-1100
Semi-erect
Light Brown
13.0
Early September
70-80
1600-2000
700-1100
110-115
Semi-prostrate
Gray
22.0
80-90
1800-2300
700-1100
Brown
Golden
Golden
White
White
White
Creamy whit
Golden brown
Creamy whit
Creamy whit
25.5
33.0
21.0
25.7
29.9
37.0
35.0
32.0
38.0
41.0
Mid August to
early September
Mid august
Mid August
Mid August
Mid August
Mid August
Mid August
Mid August
Mid August
Mid August
Mid August
106-120
100-149
57-147
105-155
90-155
91-150
93-150
86-151
122-130
118-129
Semi-erect
Semi-erect
Semi-erect
Semi-erect
Semi-erect
Semi-erect
Semi-erect
Semi-erect
Semi-prostrate
Semi-erect
120-140
100-120
90-120
100-115
100-125
110-140
110-140
120-160
120-140
120-140
1500-2300
1900-2600
1900-2600
1800-2600
1800-2600
1800-2600
1800-2600
1800- 2700
1800-2700
1800-2600
700-1300
700-1200
700-1200
700-1200
700-1200
700-1200
700-1200
700-1200
700-1200
700-1200
Planting date
Pest Management
Root diseases of chickpea
Many pathogenic fungi occurring together in the same field cause root diseases of chickpea. However,
for the purpose of clarity, root diseases are presented separately.
Fusarium wilt (Fusarium oxysporum )
Fusarium wilt is the most important disease-affecting yield in Ethiopia. Wilt occurs during seedling
and adult plant stages. At seedling stage, the disease can occur 25 weeks after sowing on susceptible
cultivar depending on the environmental conditions for wilt development. During the adult plant stage
of the crop, the infected plants show typical wilting (drooping of the petioles along with the leaflets).
When the stem of the infected plant split, black discoloration of the xylem is evident. Early wilting
causes more losses than late wilting but seeds from the later are lighter, rougher and dull.
Control measures: The best and acceptable method of wilt control is through development of
resistant cultivars.
48
Fusarium root rot (Fusarium solani)
The disease is favored by a temperature of 22-28OC and high soil moisture. The disease can appear at
any growth stage of the crop. It causes yellowing of the basal foliage, stunted growth and reddening of
the vascular tissue below the soil line.
Control measures: Since the level of resistance in chickpea to Fusarium root rot is not high, an
integrated approach that includes cultural practices (drainage), maintenance of good seed vigor and
genetic resistance is required.
Collar rots (Sclerotium rolfsii)
The pathogen has wide host range where grasses being less susceptible. The disease is usually
observed under wet warm conditions. The first visible symptoms appear as yellowing or wilting of the
lower leaves, which progresses to the upper ones. On all infected tissues, the fungus produces
numerous small round-shaped sclerotia, which are brown in color. The only economic control consists
of long-term rotations with non-susceptible host and deep plowing.
Major foliar diseases of chickpea
Historically, chickpea production has not been threatened by foliar disease in Ethiopia. However, due
to changes in chickpea production, germplasm exchanges, and changes in rainfall pattern, foliar
diseases are becoming a problem.
Ascochyta blight (Ascochyta rabiei)
Ascochyta blight is a devastating disease when weather condition (cool and wet weather) prevails.
The pathogen is seed and stubble born. In Ethiopia, it is an important disease in early-planted
chickpeas in the low lands and when rainfall is extended beyond September.
Symptoms: Above ground plant parts are affected during all crop stages. Seeds from infected pods
can show discoloration.
Control measures: Ascochyta blight can be controlled using resistant cultivars, such as Arerti.
However, other practices can augment resistance like the use of pathogen free seeds, seed treatment
with fungicides foliar fungicide spray, stubble management and crop rotations.
Stunt
Important groups of viruses affecting cool-season food legumes are those causing yellowing,
chlorosis, reddening and stunting. The viruses that are involved the foregoing symptoms are Bean
Leaf roll Luteovirus, beet western yellows virus, soybean dwarf virus and chickpea Luteovirus. They
are transmitted by aphids like Aphis craccivora and Acrythosiphon pisum
Control measures: Cultural practices such as varying sowing dates, plant density and using border
plants which are not hosts to the virus are effective in reducing yield losses. Insect pests
Chickpea is an important crop grown in different parts of the country. Despite its wide cultivation it is
attacked only by few insect pests, of African Bollworm (Helicoverpa armigera) in the field and
Adzuki bean beetle ( Callosobruchus chinensis) in the store. Cut worm (Agrotis segetum ) is also an
important pest and sporadic in its status.
African Bollworm (Helicoverpa armigera): African Bollworm (ABW) pupae undergo a
prolonged facultative pupal diapaus during the cooler months of November to March. This behavior is
partly responsible for the survival, build up and carry over potential of the pest from season to season.
Moreover, studies on seasonal flight habit of adult ABW moths revealed two population peaks in a
year- one-peak "Meher" peak after the main rain season and the other "Belg" peak after the small rain season. 49
Control measures
Chemical control: Several insecticides were evaluated for their efficacy in controlling ABW in
chickpea and of the tested insecticides Cypermethrin (45g ai/ha) and Endosulfan (472 g ai/ha) were
found effective when applied at peak flowering stage. It should be noted that insecticides for the
control of ABW must be applied when the larvae are at early stage.
Cultural control: Different sowing date and plant densities were also tested to see their impact on
the incidence of ABW in chickpea. An increase in plant density and early planting favored the
incidence of the pest. However, planting large area early in the season leads to pest dilution and thus,
it might not result in high incidence of ABW
Genetic Control
Host plant resistance: So far very few chickpea genotypes were screened for their relative resistance
to ABW. None of the tested genotypes were free of infestation. However, accession ICCV-7 was
found relatively tolerant to this pest.
Adzuki Bean Beetle
The beetle causes substantial weight loss under farmers' storage conditions. A loss assessment study
using improved variety revealed a mean weight loss of 52% within eight months of storage period.
Control measures
Chemical: Different insecticides were screened and Actellic 2% dust at the rate of 50g/ 100kg was
found effective in controlling this storage pest. However, recent studies showed that the insecticide is
less effective and frequent applications are required.
Botanicals: Several plants species were evaluated and efficacious plant species was found. Melletia
ferufinea at 5% W/W gave complete protection of chickpea for long period. Nonetheless, the toxicity
of this species to human beings has not yet been investigated.
Optimum tillage practices and weeding
Chickpea response to tillage and weed control practices conducted for 2-3 years at Akaki and Debre
Zeit from 1999-2001 indicated that first plowing at mid April before planting with weeding gave a
higher seed yield and followed by second plowing at mid April and late June before planting with
weeding.
Fertilization
From different fertilizer trails, it is confirmed that neither fertilizer rates nor sources have a marked
effect on yield of chickpea on Vertisols. However, the use of 100kg DAP/ha has been noticed to
supplement nitrogen and phosphorus requirements at early growth stage of the crop.
Harvest and Post harvest Handling
Chickpea maturity, usually 4-5 months after emergence, has been manifested by light green coloration
of pods. It is advisable to harvest when about 90-95% of the crop matures.
Threshing: It can be done by driving animals on the crop on well-prepared threshing ground or by
threshers.
Storage: Chickpea is attacked by storage pests like weevils, rodents etc. Hence, storage bins should
be placed in cool place, thoroughly cleaned, made free of overwintered pests, fumigate before putting
seeds and provide with proper air circulation. The storage bins should be building 50 cm above the
ground to protect rodents. 50
Lentil
Lentil is an invaluable source of protein (23-24%) for the vast majority of Ethiopian masses and as
such, it is consumed in different preparations: a split or whole grain stew forming the popular cereal
"enjera " or bread staple food component, and sometimes as roasted or boiled whole grain snack
alone or often mixed with cereals or other pulses. The relatively high level of lysine in lentil
compensates for low concentration in cereal grains hence when consumed in combination gives
nutritionally well balanced diet. The straw/haul is an important source of feed for animals fattening.
Besides, lentil is leading in fetching the local market price and comparably has significant export
market option in field crops. Moreover, it offers an indispensable additional advantage emanating
from its unique property in restoring and maintaining soil fertility through symbiotic biological
nitrogen fixation. Lentil can fix up to 107 kg N/ha implying fixation of about 6,500 ton N annually in
Ethiopia. Consequently, Ethiopian lentil culture is characterized by growing the crop mainly in
rotation with major cereals such as Tef, wheat, barley and others. In such culture, a yield advantage of
the succeeding cereal crop is realized because of the fixed nitrogen by the predecessor legume and
due to breakage of the life cycle of important diseases and insect pests. The production constraints
includes both biotic (insects, diseases and weeds) and abiotic (temperature, soil fertility and drought)
stresses affecting the vertical or horizontal production of lentil. Lentil is very sensitive to
environmental stresses such as drought, water logging and frosts. There are about ten important lentil
diseases in Ethiopia among which rust, root rots and Fusarium wilt are the major ones. Pea aphid is an
important insect pest threatening the crop starting from early seedling to maturity stage. Adzuki bean
beetle (Bruchids) is the most serious post harvest pest (under storage conditions). Coming up with
resistant varieties, such as Alemaya to rust (Uromyces fabae), which is devastating on lentil, was a
breakthrough in the breeding program and a relief to the subsistence farmer who has been suffering
from losing his produce of the whole field if this particular disease appears.
Improved varieties
The characteristics of improved lentil varieties recommended for production are given in Table 2.15.
Table 2.15. Improved lentil varieties, their agronomic characters and adaptation areas
Variety
El-142
R-186
Chalew
Chekol
Gudo
Ada
Alemaya
Alemtena
Teshale
Seed rate
(kg/ha)
50-65
65-80
50-65
50-65
80-100
80-90
65-90
85-90
85-95
100 seed
wt (g)
2.4-2.5
2.6-2.9
2.6-3.1
2.2-2.4
4.4-6.1
4.4-6.1
2.7-3.3
2.8-3.0
2.6-2.9
Seed color
Dark brown
Green
Yellow
Dark brown
Redish brown
Grey
Yellowish red
Dark brown
Brownish black
Seed size
small
Small
Medium
Small
Large
Large
Medium
Medium
Medium
Days to
maturity
80-109
122-143
111-128
84-91
86-151
88-157
81-136
94-126
97-129
Adaptation Zone
Altitude (ml)
Rainfall (mm.)
1650-2000
400-600
1800-2400
500-1200
1850-2450
500-1200
1600-2200
500-1200
1850-2450
500-1100
1850-2450
500-1100
1800-2600
500-1200
1600-2000
400-600
1800-2400
400-800
Cultural practices
Land preparation
Lentil is mainly grown in the highlands of Ethiopia where rainfall is usually high. Generally, lentil is
highly susceptible to excessive moisture stress and farmers plant lentil on sloppy fields or otherwise
use ridge and furrow system to drain excess water from lentil field to avoid water logging problem
specifically on Vertisols. The soil should be friable and free of weeds at planting. One deep dry
plough (March early June) and twice disking from mid June to early July depending on the
51
environment are recommended. Double yield advantage of lentil can be obtained when two to three
times oxen ploughed accompanied by twice hand weeding.
Planting Time
Luxurious growth followed by severs lodging due to early planting and terminal drought stress due to
late planting should be avoided to get maximum yield. Late June to mid July planting is recommended
in both mid to high altitude areas.
Seed rate
Response to planting densities varies among lentil genotypes/varieties depending on seed size and
growth habit of the specific cultivars. Erect growth and large seeded genotypes need higher seed rate
where as prostrate and small seeded ones need relatively lower seed rates. Either lentil can be planted
by broadcasting or in rows however, broadcasting is quite common. For row planting, 20 cm row
spacing and 5 cm between plants spacing is recommended. Seed rate of 65, 80 and 100 kg/ha seeding
rate for small, medium, and large-seeded lentil varieties, respectively is optimum.
Fertilization
Lentil is found non-responsive to N and P fertilizers on Vertisols. However, 100kg DAP/ha is
recommended for most legumes as a starter until the plant becomes self sufficient in N fixation and
furnishing phosphorus needs.
Pest management
Insect pests
Six insect species were identified as important insect pest in different lentil growing regions of the
country. These are Pea aphid, Adzuki bean beetle, Black bean aphid Bean flower thrips and ABW. Of
which, Pea aphid, and ABW are important insect pests.
Economic threshold level determination: Although the economic threshold level of a given
insect pest is affected by several factors, spraying of lentil at a density of 25-50 pea aphids per 10 cm
x 13 cm white board is economical. However, since aphids have high reproduction rates frequent
inspection of the field is required.
Control measure of pea aphid
Insecticide screening: Several insecticides were evaluated and Primicarb (Primor) 50% WP,
Primiphos-Methyl (Actellic) 50% EC, Ofunack 40% EC and Dimethoate (Roger) 40 EC were
effective in reducing the population of this pest.
Cultural control: Plant density has no effect on the incidence of pea aphid on lentil and early
planting expose the crop to more aphid attack. However, planting large area early in the season leads
to pest dilution and thus, it might not result in high incidence of pea aphid in lentil.
Major diseases of lentil
Lentil production is affected by wilts, foliar diseases, and root rot pathogens.
Root diseases
Wet root rot (Rhizoctonia solani)
The disease affects seedlings when warm, moist conditions are prevalent. Seedlings become less
susceptible with maturity. Seedling damping-off can be severe when soil moisture and soil surface
organic matters are high.
Symptoms: Seedling symptoms appear as water-soaked lesions turning reddish-brown to brown. On
older plants, reddish brown, sunken lesions may occur on the hypocotyle sometimes girdling the
entire plant, resulting in severe plant stunting or death.
52
Control measures: Rotation with cereals, clean tillage of field prior to sowing Fusarium wilt (Fusarium oxysporum)
Fusarium wilt is severe on lentil mainly grown on residual moisture in the highlands dominated with
Vertisols. Wilt is severe during warm weather.
Symptoms: Symptoms appear at seedling and adult plant stages. Wilt in adult plants can appear
from the flowering to late pod filling stages. Seedling wilt is characterized by sudden drooping
followed by drying of leaves and deaths of seedlings. The infected roots when split show very little
vascular discoloration.
Control measures: Adjusting sowing dates and use of resistant cultivars. The National Lentil
Research Project is aiming to develop wilt/root rot resistant cultivars.
Collar rot (Sclerotium rolfsii): The disease is prevalent in areas with high soil moisture in the
seedling stage of the crop.
Symptoms: The affected seedlings lie flat on the ground. The typical symptoms are seen near the
collar region, which is rotted and discolored. On the affected collar region, white strands of the
pathogen are characteristic rapeseed like brown sclerotia are seen on the affected collar region. Control measure: Adjusting sowing dates to avoid high soil moisture and temperature. Straw
should be well decomposed before planting lentil.
Foliar diseases of lentil
Foliar diseases caused by fungi are the major bottleneck of lentil production in Ethiopia.
Rust (Uromyces fabae)
Early infection in the crop growth stage and environmental conditions such as temperature ranging
from 20-22OC and wet weather can result in complete crop failure.
Symptoms: Rust pathogen infects all aerial plant parts. Brown uredia are formed on both sides of
leaves and other plant parts. At maturity, dark-brown telia develop on infected plant parts. The
pathogen completes its life cycle on lentil. The pathogen also affects faba bean, chickpea and grass
pea.
Control measures: The most effective means of combating rust is using resistant cultivars. In the
area of developing rust resistant breeding, the National Lentil Research Project developed highly
resistant cultivars like Adaa and Alemaya that are being widely grown by small-scale farmers where
rust occurs at epidemic proportion in each season. For July planting areas, cultivars that escape rust
disease like Chekol are developed. In agro-ecologies where there are no resistant cultivars, adjusting
sowing date, crop rotation, fungicide spraying (Dithane M-45 at the rate of 1 l/ha) and field sanitation
can be practiced to mitigate the effect of rust on lentil yield and quality.
Ascochyta blight (Ascochyta lentis)
This disease usually observed in research center and few farmers’ fields. It can be a potential threat
affecting both quality and quantity if lentil is introduced in low lands.
Symptoms: Above ground plant parts are affected during all crop stages if environmental conditions
(cool and wet weather) prevail. Tan spots are seen on leaflets, pods and stems speckled with black
fruiting bodies called pycnidia. Seeds from infected pods can show symptoms.
Control measures: use of pathogen free seeds; seed treat with fungicides (thiabendazole and
benlate); foliar fungicide spray (Chlorothalonil at 2-3 l/ha) as single application at flowering to early
pod stages; 2-3 years crop rotation and use of resistant varieties.
53
Weeds of lentil
The commonest and important weed species identified in lentil were; Phalaris paradoxa, Argemone
mexicana , Bromus pectinatus, and Cyperus rotundus. Common Bean (Haricot bean)
The wide range of growth habits among bean varieties has enabled the crop to be cultivated well
under different agro-ecological conditions. Prostrate bush types in the central zone achieve rapid
ground cover, compete well with weeds, and avoid competition with tef for labor. Climbers are
widely grown on homestead fences in the western region, where they can make full use of the longer
growing season. Some of them can also be fit for inter-cropping. Early maturity and a moderate
degree of drought tolerance have led to the crop’s vital role in farmer’s strategies for risk aversion in
drought prone lowland areas of central, eastern, and southern Ethiopia. Farmers increase their bean
area considerably in years when late onset of the rains prevent normal cereal establishment. This crop
is better in escaping (short maturity period) drought than sorghum and in some years provides the
only harvest in drought affected areas of the Rift Valley. In eastern Ethiopia, farmers practice varietals
mixtures, which have helped to avoid disease and insect pest outbreaks. Soil erosion is relatively low
under a bean crop canopy, and the straw is stored as a high quality supplement to cereal fodder during
the dry season.
Production environments
Altitude and temperature
Common bean has a wide range of adaptation. In Ethiopia, common bean grows well between 1400
and 2200 masl. The minimum and maximum mean temperature requirements are 10 and 320C,
respectively. Beans do not grow well at low altitudes as high temperatures cause poor seed set. At
high altitudes, the growth is slow and beans are sensitive to frost.
Rainfall
Areas with medium rainfall ranging from 350 mm to 700 mm (70 to 100 days) are good with a welldefined rainy season so that harvesting is done in dry weather. Some rain is required for the critical
flowering period. Very high rainfall causes flower drop and increase the incidence of diseases. The
relative humidity should not exceed 75%.
Soils
Beans can be grown on a variety of soils. I can be grown on light sandy soils to heavy clay soils if
they are well drained as beans are sensitive to water logging. PH should be above 5.0
Improved varieties
In the past three decades of research undertakings, twenty varieties were developed and released
together with appropriate crop management packages recommended for these varieties (Tables 2.16
and 2.17). In addition, resistance sources of major diseases and insect pests were identified.
54
Table 2.16. .Characteristics and adaptation of improved bean varieties for domestic consumption
Variety
Year
of release
Days
to maturity
Roba-1
1990
75
Yield
on station
(q/ha)
21
Atendaba
Zebra
Brown Speckled
1997
1998
74
76
78
24
27
11
Beshbesh
1997
76
Red Wolayta
1974
Melke
Seed
size
Suitable area
Seed Rate (kg)
Row
Broadcast
Small
90-100
110-120
Medium
Medium
Large
90-100
80-90
90-100
110-120
100-110
110-120
25-30
Small
70-80
90-100
77
22
Small
90-100
110-120
1997
78
20-25
Large
70-80
90-100
Nasir
Dimtu
Goberashia
Ayenew
Goffa
Tabor
Wedo
Melka Dimma
2003
2003
1998
1997
1997
1998
2003
2006
88
86
23-25
20-23
80-90
80-90
70-80
80-90
80-90
100-110
100-110
90-100
100-110
100-110
91
23
Small
Small
Large
Large
Large
Small
Large
Medium
80
90-100
Batagonia
2005
150
18
Medium
30
Anger
2005
91
23-30
Medium
100
Tibe
Haramaya
2004
2006
98
100
22-28
20-32
Medium
Medium
60
50-70
Bobe Red
2006
92
25
Medium
90
Across all locations
(environments)
Central Rift Valley
Central Rift Valley
Across all bean growing
environments
Specific for Southern region
(Wolaita area) (for bean fly
resistance)
Across all bean growing
environments
Specific for Southern region
(Wolaita area )(for bean fly
resistance)
Across all location
Across all location
South western (Jima area)
East and West Hararghe
East and West Hararghe
Hawassa area (South)
Welo
Central rift valley and Similar
environments
Altitudes of Sidema and
Wolaita zone
Bako, Bffoboshi, loko and
similar areas
Bako and Tibe
All bean growing areas of
eastern Hararghe
Central rift valley and similar
areas
110
100-120
Table 2.17. Characteristics and adaptation of improved small white (navy) bean varieties (export type)
Variety
Year
released
Days to
maturity
Yield (q/ha)
On- station On- farm
95-100
95-100
95-100
85-90
15-20
20-24
22-25
20-22
10-15
15-20
18-20
15-20
Mexican-142
Awash-1
Awash Melka
Argene
1972
1990
1998
2005
Seed rate (kg)
BroadRow
planting
casting
100-120
90-100
100-120
90-100
100-120
90-100
100-120
90-100
TA01JI
2005
100-120
90-100
85-90
22-25
19
Chore
Cherecher
2006
2006
100-120
100 -110
90-100
90-100
87-109
98
23
22-28
21-27
Agro-ecology
All over the country
Central rift valley
All over the country
Central rift valley and similar
areas
Central rift valley and similar
areas
All over the country
Hararghie highlands and similar
areas
Cultural practices
Land preparation
As beans have relatively bigger seeds, they do not need a fine seedbed. However, the land should be
ploughed properly and should be free of weeds, soil clods and other undesirable materials. Plowing
55
should be done just after harvesting the previous crop and before the soil is too hard to till. This
operation will help to turn down the vegetation and the remains of the previous crop. A second
plowing can be made one month later. A third plowing can follow just before sowing. Pulverizing all
soil clods with a hoe is also important.
Planting time
Time of sowing is very important. Delays in sowing reduce potential yield considerably. For any
growing areas, the proper sowing time is when conditions are ideal for germination, emergence,
establishment, and growth of bean. As they take 75-95 days to maturity at medium altitudes (10001700 masl) and about 110 days at high altitudes (1800-2200 masl), the sowing should be done about
70 days before the end of the rains at medium altitudes and about 100 days before the end of the rains
at high altitudes. Too late sowing will lower the yield. Important factor during sowing is depth of
planting. Even if it is not possible to generalize, 4-8 cm is the proper range to use depending on seed
size, soil type, and climate. Under hot and dry conditions and rainfall is unreliable for deep sowing the
seed should be given more protection from sun baking and places the seed in a possible advantage not
to be induced to germination by light showers. However, such practice in areas of heavy soil and good
rainfall results in poor emergence. The seed can be row planted or broadcasted followed by
subsequent plowing to cover the seeds. A summary of planning time is given in Table 2.18.
Table 2.18. Research supported bean-planting time
Production area
Southern Ethiopia (lowland area)
Southwestern
Central Rift Valley
Rainy season
3rd week of March
3rd week of April
week of June
Planting time
1st Week of April
2nd Week of April
End of June to 2nd Week of July
In the rest part of the country. the planting time is mostly from 2nd week of June to 3rd week of July.
Sowing method and seed rate
If possible, bean should be sown in rows for easier weeding. The row sowing can be done by hand or
by a seed drill. It is also possible to sow by making a furrow with the local plough, seed in the furrow
and cover with soil from the next furrow. If broadcasting is used the seed can be covered by plowing
with an ox plough or by disc harrowing. Depending on seed size, soil type, and climate, the proper
range for seed depth is from 4 to 8 cm. Seed rate used depends on:
•
•
•
seed size (expressed as 100 seed weight),
row width, and
intra-row spacing.
Spacing depends on the size of mature plant; both above ground and below ground, and how the land
is used efficiently. Seed rate should be chosen to give about 300 to 500 thousand plants per hectare.
To achieve this plant population a seed rate of 70 to 100 kg/ha is required for row planting and 110 to
120 kg/ha for broadcasting based on seed size and quality. A higher seed rate should be used for
broadcasting due to more uneven distribution of the seed and poorer field germination. For the Central
Rift Valley, the spacing between rows should be 40 cm, and seeds in the row 10 cm apart. It is
important to secure optimum plant population in beans at planting. Seed quality, soil moisture at
planting, soil insects and/or seedling diseases are additional factors to be considered for optimum
stand establishment. Plant nutrient management
Soil fertility is one of the bean production constraints in Ethiopia. The soils are generally deficient in
N and P. Bean is responsive to N, P and K fertilizer when soil levels are inadequate to support yield
levels possible with existing soil moisture and growing season climatic conditions. Crop response to a
nutrient is affected by soil moisture, temperature, placement, tillage, and crop. Thus, agronomists
should know and give due emphasis to soil types, climate, and the bean plant itself. If other crops
56
respond to phosphorus in the area apply around 50-100kg DAP/ha during planting. The small amount
of nitrogen will help the plants to get a good start. When the plants are deficient in nitrogen they show
leaf yellowing, at this moment, 50-100 kg urea could be applied as top dressing before flowering. Bean-based cropping systems
Crop rotation
In Ethiopia, beans are grown in rotation with cereals. Growing of beans year after year on the same
land will result in build-up of pests and diseases. Beans should preferably be not grown more often
than every 3rd to 4th year on the same land.
Intercropping
Shade tolerance and early maturity contribute to the predominant position of beans as an under storey
intercrop for sorghum, maize, coffee and enset in southern and eastern zones (85% of all sorghum in
the eastern highlands is intercropped with beans). Beans can be inter-planted with maize or sorghum
in the same field either by broadcast planting the two crops together or by planting in different rows
or by planting cereals in rows and broadcasting beans in between. This intercropping system not only
improves the total productivity by 20% but can also reduce weed incidence and improve soil fertility.
Early maturing bean varieties planted simultaneously with maize in 2:1 maize:bean intercrop pattern
can give sustainable yield and income advantage in the rift valley.
Alley cropping
Alley cropping of beans with perennial leguminous shrubs such as Sesbania sesban or Cajanus cajan
(with 4 to 6 m between perennial hedge rows) can reduce soil erosion and also improve soil fertility.
This system can produce an additional biomass of 2 to 3 t/ha, which can be used for fodder or for
mulching or for green manure application without any significant grain yield reduction of beans.
Pest management
Disease control
Common beans suffer from a wide range of leaf, stem and root diseases including common bacteria
(CBB), rust, anthracnose, angular leaf spot, floury leaf spot, web blight, halo blight, aschochyta
(Phoma) blight and bean common mosaic virus (BCMV). In Ethiopia CBB, rust and anthracnose are
the most important and are widely distributed, while the others, though important, are much more
restricted in their distribution.
Common bacterial blight
Common bacterial blight caused by Xanthomonas campestris. Phaseoli is ranked among the most
important diseases on bean in Ethiopia. It is most prevalent in the low altitude areas and at various
degrees, wherever beans are grown. While this disease occurs, its prevalence varies within the same
country and within season. The actual yield loss caused by this pathogen is estimated at 21%. The
incidence and severity has been reported to be very high in many parts of the country. Estimated yield
losses in United States, Canada and Colombia ranges between 13% and 60%. Though no immune
variety is found, efforts are currently being made to produce varieties resistant or tolerant to these
diseases.
Symptoms
Initial symptoms appear as water soaked spots on the lower surface of the leaves. As the spots
enlarge, the centers become necrotic and irregular. Lesions later merge and surrounded by narrow,
yellow zones, which turn brown. On pods small, water soaked, greasy- looking spots appear. These
enlarge, becoming dark reddish brown and slightly sunken. Under humid conditions a yellow, slimy
exudates may be produced, forming a yellow crust when dry. The Bacteria occurs on and inside seed,
57
which may bear pale yellow lesions and become wrinkled or remain symptom less. Lesions may also
develop on stems, which may break under windy conditions.
Control
Various methods of control have been tried for common bacterial blight. These include seed treatment
with copper fungicides, cultural control methods such as crop rotation, deep ploughing, and disease
free seed, and use of resistance varieties and dry weeding. Practically, it can be achieved for shortterm control by use of disease free seed together with crop rotation but for long-term control, using
resistant or tolerant varieties is effective. Recommended varieties such as Awash-1, Roba-1, Nasser,
and Awash Melka are less affected by bacterial blights.
Anthracnose
Anthracnose is caused by Colletotrichum lindemuthianum, which is wide spread and common, often
causing severe damage. It is the most important disease of beans worldwide. Yield losses can reach
100%, especially when infected seed is used. Based on results in Tanzania, it has been estimated that,
for each 1% in anthracnose 9kg/ha reduction. The pathogen occurs in numerous pathogenic races.
Symptoms
Leaf symptoms appear initially on the lower leaf surface. Dark red to black lesions occur along the
veins. On larger leaf veins, these lesions expand into sunken cankers, within which acervuli bearing
conidia are produced. Lesions also commonly develop on cotyledons as well as on petioles, branches,
stems, and pods. Pod lesions are typically sunken and contain masses of salmon-pink conidia, which
are mostly cigar shaped.
Control
Use of healthy seed, rotation of two to three years and field sanitation (bean straw) are effective
measures to control anthracnose in the field. Treatment of seeds with Benomyl (2.5g/kg of seed) and
spray with Benomyl (0.4kg/ha) and Mancozeb (00.2% concentration) alternatively in 5 to 7 days
interval from just before flowering to harvest. The spray will only pay in high value seed crops
Bean rust
Bean rust caused by Uromyces appendiculatus is a widespread and important disease of beans in
eastern and southern Africa. In Ethiopia, severe out breaks of bean rust were reported from the south
and southwestern parts and the mid altitude and cooler regions. A severe outbreak of bean rust
resulted in 85% yield loss in the popular and widely grown, but susceptible cultivar, Mexican 142 and
30% for the partially resistance Cultivar, 6-R-395. The loss depended on the resistance level of
cultivars, location and season. These results related with the variation in yield and yield loss.
Symptoms
Minute yellow raised spots appear on both sides of infected leaves as well as on petioles and pods,
These ospots enlarge and rupture the epidermis to form reddish brown uredial pustules, which may be
surrounded by yellow haloes and then by rings of smaller secondary pustules. The dry, powdery
spores are typical of rust fungi. As the infection ages, much of the leaf becomes chlorotic while the
tissue colonized by the fungus remains green (green islands). The pustules darken as the pigmented,
thick walled, single called teliospores are produced and the gradually dies.
Control
Growing resistant varieties is a good control method. The recommended varieties have a good partial
resistance against rust, especially Awash and Roba-1. Sanitation, crop rotation, and varietal mixtures
are found to be very helpful control measures. Spraying mancozeb or systemic fungicides at different
crop growth stage can be used as control measures.
58
Angular leaf spot
Angular leaf spot of beans is caused by the fungus phaeoisariopsisgriseola. It is found in tropical, sub
tropical, sub tropical and temperate regions of the world. The fungus has numerous hosts, among
them phaseolusvulgaris. P. Lunatus, P.acutifolius, pisum sativum and Vigna sinensis. It is widely
distributed throughout the continent of bean growing areas.
Symptom
Initial symptoms of this disease are gray spots that generally appear on the lower leaf surface. Later
on, these spots turned brown and covered with small columns of hyphae, called synnemata. Lesions
are angular because the leaf veins limit them. The angular lesions are also visible on the upper leaf
surfaces; Lesions may cover large areas of the leaf, causing it to appear chlorotic. Occasionally,
partial premature defoliation occurs. Lesions on the pods, stems, and petioles are reddish brown and
frequently have darker borders.
Control
Plant debris and infected seed are the main sources of infection; wind, wind-driven rain, and soil are
the principal means of dissemination. The use of clean seed, burial of infected debris, and rotation can
decrease disease severity. However, in Africa the common practical measures are the use of cultivar
mixtures and inter cropping with cereals. Although fungicidal seed dressings can also be effective, the
use of resistant cultivars is the best strategy
Halo blight
Halo blight, is caused by the bacterium Pseudomonas syringae PVl. Phaseolicola, is a wide spread
and important disease favored by cool conditions. The crop losses have not been adequately
quantified in Africa. Losses up to 43% have been recorded elsewhere.
Symptoms
Initial symptoms appear three to five days after infection as small, water-soaked spots on the leaves.
A halo of greenish Yellow tissue then develops around the lesion. Under epidemic conditions stems
and pods may also become infected, the latter leading to seed infection. On the pods, the lesions are
rounded with a greasy appearance and distinct halos
Control
Use of resistant varieties is considered the most efficient control measure.
Bean common mosaic virus
Symptoms
Bean common mosaic virus (BCMV) may induce a variety of symptoms in systemically infected
plants, including mosaic, green vein banding, leaf curling, secondary leaf malformation, and plant
stunting. Certain strains of BCMV can induce a systemic necrosis reaction in mosaic resistance plans.
This hypersensitive reaction, known as black root, appears first in the younger trifoliate leaves, which
show a characteristic vein necrosis. The necrosis advances rapidly down the stem affecting the entire
vascular system, including the pods (if formed) and roots. Symptom expressing is dependent upon the
bean genotype, strain of the virus, environmental conditions, and growth stage of the plant at which it
becomes infected. Generally, the younger a bean plan is infected, the more pronounced are the
symptoms that develop. In addition, the seed transmissibility of BCMV decreases considerably when
susceptible bean plants become infected after flowering.
Control
Use of healthy seeds and eliminating weeds and alternate hosts found grown nearby can be applied to
control the viral disease.
59
Insect pest control
Bean stem maggot
Ecological studies carried out so far show that three species of bean stem maggots (BSM)-commonly
known as bean fly-occur in Ethiopia. These are Ophiomyia phaseoli (Tryon), 0. spencerella
(greathead) and 0. centrosematic de Meijere. The adults are very small flies, about 2mm in length.
The larvae (maggots) are white and have a length of about 3mm when fully grown. As soon as the
seedlings have developed their primary leaves, deposition of eggs takes place on the leaf blades near
petioles. The place, where an egg has been inserted under the epidermis appears as a sunken, lightcolored spot, so that the base of the attacked leaves shows a characteristic speckling. The maggots
mine through the leaf blade, petiole, and main stem to the base of the stem. There the feeding activity
by the late larval stages causes a swelling with numerous cracks. Young plants attacked start
withering, and usually will die within a short time. Pupation takes place in the crack of the swollen
stem base. BSM is wide spread in Africa, Asia, and Australia. Attempts made to develop integrated
management of BSM. These include cultural, host plant resistance, biological control, and insecticidal
control.
Control
Cultural control studies on management of BSM concentrated on the effect of sowing date and plant
density. Sowing dates were site specific; for example, bean fly numbers were lower and crop yields
higher in early sown beans in the drier areas of Mekelle, Kobo and Melkassa where as at Hawassa,
which has higher rain fall, bean fly numbers declined with late seeding. On the other hand lower bean
fly numbers and higher yields were with higher plant densities of 300,000-500,000 seeds/ha at all
locations. Growing resistant varieties to BSM, for example, Beshbesh and Melke is another feasible
option. Seed dressing with endosulfan at the rate of 5g a.i/kg of seed gives adequate control of BSM.
Bean bruchids (Acanthoscelides obtectus)
A serious stored products pest, adapted for life and reproduction in the dry conditions of produce
stores, although many infestations may start in the field on the ripening seeds; it is multivoltine in
produce stores on pulses. Most serious on Phaseolus beans, but it is recorded damaging many other
different pulses in storage. Eggs are laid either loosely in the produce, or on the pods in the field, or in
cracks in the beans testa; each female lays 40-60 eggs; hatching takes 3-9 days. Many infestations
start in the field, and the larvae feed on the ripening seeds. Larval development through four instars
takes 12-150 days. The larvae are white, curved, thick-bodied, and legless and are found inside the
bean seeds. Pupation takes place within a small cell inside the bored seed, behind a thin ‘window’
composed almost entirely of testa (for easy emergence of the adult); pupation usually takes 8-25 days.
Adults are small, 2-3 mm long, stout, brownish-black with pale patches on the elytra.
Mexican bean beetle (Zabrotes subfasciatus)
It is a major pest of beans in certain parts of the tropics. Even though, phaseolus bean is the usual
host, the pest is also recorded on cowpea and other legumes. The pods are bored and the seeds eaten
by the developing larvae. The eggs are lid stuck on to the pods or on the testa of beans, and the larvae
feed on the cotyledons. The adult beetles are oval, small (2-2.5mm), with long antennae. The hind
femur is without spines, but there are two moveable spurs at the apex of the hind tibia. Attempts were
made to develop IPM of bruchids.
Control
Use of resistant varieties, botanicals (neem, pepper tree, and Persian lilac) and applying primiphosmethyl at the rate of 4-6 ppm a.i. gives effective control of Bruchids
African ball worm (Helicoverpa armigera)
The adult moth has a wingspan of about 35 mm and appears mainly in two color varieties with brown
forewings or grey, respectively. The caterpillars are up to 40 mm in length and have a characteristic
60
undulating, white band on each side of the body. Their color varies from black to green, brown,
reddish-brown, whitish, and orange. Caterpillars cause heavy damage to flower buds and pods. One
caterpillar can damage a number of pods and buds by moving from one to the other.
Control
All crop residues must be burnt after harvest; strip cropping of 10-15 rows of bean with two rows of
maize reduces ABW damage to beans. Planting of an early maturing maize variety such as Katumani
about 10 days before planting common bean is recommended. Use of cypermethrin, applied at 150g
a.i/ha gives effective control of ABW.
Weed control
Beans do not compete well with weeds, particularly at early stage. Also weeding bean late in the
season critically affects bean yields due to mechanical damage. Weeding is important and is made
much easier if the beans are sown in row. For Bako areas, 80-100% yield loss due to weed was
reported. Around Melkassa area, leaving beans unweeded can result in 37-64% yield loss based on
soil types. The weeding can be started 2-3 weeks after sowing and continue to about 5 weeks after
sowing. To minimize the weed problem and increase the yield of beans weeding at least once around
30-35 days after emergence is ideal. Weeding should be finished before the flowering starts. If the
beans are sown in rows weeding should preferably be done by hoeing with a light hoe or by using a
row-weeder. Hand weeding will normally be the cheapest and most effective but if enough laborers
are not available chemical weed control is possible. In that case use of herbicides such as alachlor
(2.92kg a.i./ha) or pendimethalin (1.50 kg a.i./ha/ or flurodifen (2.0kg a.i./ha) after sowing and before
emergence of beans is recommended. In areas where perennial weeds such as Digitaria, Cynadon,
Cyperus and Launea are a problem, one supplementary hand weeding might be very important.
Harvest and post-harvest handling
Beans can be harvested when all the pods are yellow. Early harvest of colored beans can cause
discoloration. The plants are pulled out with the roots and this can preferably be done early in the
morning when the plants are slightly moist as this minimizes shattering. The plants are stacked in the
field until they are dry or brought to the threshing ground and stacked there for drying. The threshing
can be done by oxen or by driving over the plants with a tractor. It can also be done by beating the
beans with a stick. After threshing, beans can be cleaned by hand winnowing or by a winnowing
machine. As several diseases are carried over from one season to the next on the straw and chaff left
in the field and on the threshing ground, a thorough sanitation should be carried out after the bean
crop, i.e. all residues should either be fed to cattle within three months after harvest or be burned.
Soybean
In Ethiopia, soybean is gaining importance in recent years. The area seeded to soybeans is expected to
increase due increased demand of domestic processing industries and increased demand for use in
animal feed. Ethiopia is strategically located closer to the world's largest consumers. This is good
opportunity for the country to target soybean as potential export commodity. The crops determinate
and indeterminate growth nature makes it fit to different production zones. Soybean is potential crop
for import substitution and key crop for industry and fighting malnutrition. Acceptance of the crop by
farmers is now increasing. However, its cultivation has not spread very much. Average soybean yield
is very low as compared to other crops growing in the same season. In addition to productivity, there
are no large variety of preparation techniques and processing methods and dishes made out of soybean
and soya products. This is because, in many parts of the country, soybeans are not known and cannot
be found in the local market, and it requires special processing techniques to convert them into an
61
edible, tasty food. These difficult techniques are not familiar in most part of the country. The efforts
to introduce them have not been very successful yet on a larger scale. Hence, inclusion of soybean as
major crop in the crop production system requires innovative production, processing and utilization
technologies and approaches. Increasing soybean production and productivity is will contribute
substantial for the development of the country economy and for the well-being of its inhabitants.
Production and productivity in turn should be aimed at enhancing sustainability, which requires wise
and efficient utilization of existing resources. Hence, the research should assist the farming
communities to find ways of feeding and providing other needs to the increasing populations. The
nutritional value of the diets of urban and rural poor has been declining due to lack of domestic
animals reared per family and the decline in the supply of animal products. Carbohydrates dominate
the diets of the majority of urban and rural poor. Most people have no access to protein sources like
egg, milk, and meat. These people are suffering from malnutrition and its consequences. Probably,
children are the most seriously affected group by this problem. To tackle this problem the scaling out
of the present efforts on promotion of soybean production and utilization has paramount importance.
The rural poor have also limited sources of income in order to buy the necessary domestic needs and
agricultural input. The cultivation of soybean will open a new way of earning income since soybean is
highly demanded for the manufacturing of protein isolates and concentrates, oil and other industrial
products. Due to low production and supply of soybean in the domestic market, the soybean base
agro-industries in the country have been importing large amount of defatted soybean annually and
there is big edible oil shortage in the country. So, to improve the low income and malnutrition
problem of the poor, it is crucial to adopt a strategy that brings about wide impact by disseminating
the existing soybean technologies & promoting the production and utilization of soybean among small
holder farmers. Lack of access to improved technology and low prices for their product is major
challenge in crop production. To deal with this integrated effort will be required to disseminate the
available technologies widely and develop mechanisms through which farmers get those technologies
easily in their locality on sustainable basis. Cooperative based technical package dissemination can
help to reach many farmers with improved technologies and information on agriculture and rural
development.
Improved varieties and management
Awassa-95, AFGAT and Belessa-95
Awassa-95 with breeding code G-2261 and Belessa-95 with PR-149-6 were evaluated in national
variety trials from 1996 to 2001. Awassa-95 was tested over 10 environments whereas Belessa-95
over 9 environments. Base on the yield in the respective trials, agronomic performance, and disease
reaction PR-149-6 was released in 2003 and given the name Belessa-95. Likewise, G-2261 was
provisionally released in 2003 and got full release in 2005 as Awassa-95.
Belessa-95 is long maturing variety suitable for production in high rainfall areas especially moist
humid western and southwestern part of the country in altitude ranging from 580 to 1800m. It may
require 134 to 169 days depending on altitude and temperature to reach to physiological maturity. Its
yielding potential is ranging from 1724 to 2980 kg/ha at on-station and around 2085 kg/ha at on-farm.
Awassa-95 is relatively early to intermediate maturing variety requiring around 120 days reaching to
physiological maturity depending on the temperature, altitude and moisture availability of the growing
locations. It is suitable variety for production in intermediate rainfall areas. The areas receiving
500mm rainfall in growing period is conducive for its production. Its yield potential is ranging from
1769 to 2600 kg/ha at on-station and 1960 to 2800 at on-farm depending on production environment.
AFGAT (TGX-1892-10F) medium maturing, the genotype expressed remarkable variability for
yielding potential in the all test locations. The mean grain yield of TGX-1982-10F ranged from
62
1800kg/ha -2800kg/ha and it is most reliable having about 75% chance of outperforming the best
check. TGX - 1892-10F was released in 2007 and given the name AFGAT.
Morphological descriptions and agronomic performance of the varieties presented in Table 2.19. The
varieties are susceptible to water deficit at germination and late podding and seed set. Belessa-95
requires uniform and enough moisture for uniform germination and as compared to Awassa-95 more
sensitive to low moisture at germination. Water deficiency reduces plant size and restricts root growth
hence cut production. The crop cannot withstand water logging which reduces oxygen availability to
roots.
Table 2.19. Morphological descriptions and agronomic performance of released varieties
Traits
Breeding code
Growth habit
Days to 50% flowering
Days to 90% maturity
Plant height (cm)
100 seed weight (gm)
Yield (kg/ha)
•
Research field
•
On-farm
Awassa-95
G-2261
Indeterminate
42 – 64
90 – 129
42 – 60
14
Belessa-95
PR-149-6
Indeterminate
55 – 90
134 – 169
72 – 100
13
AFGAT
TGX - 1892-10F
Indeterminate
45 – 70
120- 131
42 – 60
16
1769 - 2600
1960 – 2800
1724 - 2980
2085
1800 - 2800
1560 – 2900
Williams, Crowford, Awassa-95
•
•
Length of growing period:
90-120 days;
Soil type: High yield could be generally obtained with soils having the following characteristics
o
o
o
•
•
•
•
Reasonable clay content to allow retention of soil moisture. Sandy soils are ok provided rainfall is adequate
and evenly distributed during crop growth
Freedom from excessive water logging problems
Fertile soil with good tilth and neutral pH (6-7);
Altitude (m): Can grow in altitude range of 300-2200m but potential yield could be obtained from 1300 to
1700 m;
Rainfall (mm): 500 mm at cropping season. Two critical periods with respect to water requirements:planting to emergency and pod-filling;
Temperature (Min-Max): 20-400c but optimum 23-250 C; and
Major growing wereda of the commodity: Sidama, Burji, Western and South Western part of the country
Davis, Clark 63K, Cocker and AFGAT
•
•
•
•
•
•
•
•
•
Length of growing period:
121-150 days;
Soil type: High yield could be generally obtained with soils having the following characteristics;
Reasonable clay content to allow retention of soil moisture. Sandy soils are ok provided rainfall is adequate
and evenly distributed during crop growth;
Freedom from excessive water logging problems;
Fertile soil with good tilth and neutral pH (6-7);
Altitude (m): Can grow in altitude range of 300-2200m but potential yield could be obtained from 1300 to
1700 m;
Rainfall (mm): 500 mm at cropping season. Two critical periods with respect to water requirements:planting to emergency and pod-filling;
Temperature (Min-Max): 20-400c but optimum 23-250c; and
Major growing wereda, of the commodity: Sidama, Burji, Western and south western part of the country
63
TGX-13-3-2644, Belessa-95
•
•
Length of growing period:
Greater than 150 days;
Soil type: High yield could be generally obtained with soils having the following characteristics
o
o
o
•
•
•
•
•
Reasonable clay content to allow retention of soil moisture. Sandy soils are ok provided rainfall is adequate
and evenly distributed during crop growth
Freedom from excessive water logging problems
Fertile soil with good tilth and neutral pH (6-7);
Altitude (m): Can grow in altitude range of 300-2200m but potential yield could be obtained from 1300 to
1700 m;
Rainfall (mm): 500 mm at cropping season. Two critical periods with respect to water requirements:planting to emergency and pod-filling;
Temperature (Min-Max): 20-400c but optimum 23-250c;
Major growing wereda, of the commodity: Western and south western part of the country; and
Quality traits ( oil content %, 31.2% for Belessa and 27.4% for TGX-13-3-2644) Summary of the recommended varieties of soybean and their adaptation areas is presented in Tables
2.20 and 2.21.
64
Table 2.20. Characteristics of some soybean varieties recommended or released for cultivation in Ethiopia.
Characteristics
Maturity group
Days to maturity
Growth habit*
General
adaptability
Williams
Early
90-120
D
Short rain
fall areas
Crawford
Early
90-120
D
Short rain
fall areas
Seed rate (kg/ha) 60
60
Spacing (cm)
40 x 5
40 x 5
Yield( kg/ha)
15 – 20
15- 20
* D = Determinate, ID = Indeterminate
Clark 63K
Early
90 -120
ÍD
Short
rainfall
areas
60
40 x 5
15 - 20
Awassa-95
Early
90-120
ID
Short rainfall
areas
Cocker 240
Medium
121 - 150
ID
Intermediate and
long rainfall areas
60
40 x 5
17 - 26
60
60 x5
15 - 25
Variety
AFGAT
Davis
Medium
Medium
121-150
121-150
ID
ID
Intermediate
Intermediate
and long
and long rainfall
rainfall areas
areas
60
60
60 x 5
60 x 5
15-29
15 - 25
65
Jalale
Medium
120 - 133
ID
Intermediate
and long
rainfall areas
60
60 x 5
16 - 21
Cheri
Medium
135
ID
Intermediate
and long rainfall
areas
60
60 x 5
24
Belesa-95
Late
> 150
ID
Long rainfall
areas
TGX-13-3-2644
Late
> 150
ID
Long rainfall
areas
60
60 x 5
17 - 29
60
60 x 5
20 - 25
Table 2.21. The likely areas of adaptation of soybean varieties
Location
Gojebe (1250m)
Jimma (1750m) and surrounding
Gambella (520m)
Metu
Awassa (1700m)
Arsi Negelle ( 1960m)
Belle Wolayta (1400m)
Arbaminch (1400m)
Bako (1650m)
Anger Gutin (1400m)
Deddessa (1300m)
Pawe (1200m)
Lower Birr Shelleko (1530m)a
Melka Worer (750 m) b
Zeway/Alage
Wolediya (1900m), Bure (2150m) and
Harbu (1500m)
Varieties
Cocker-240
Cocker-240, Davis, Clark-63K, TGX-3-3-2644,
Awassa-95, Belessa-95
Awassa-95, Belessa-95
Davis , Clark -63K
Williams, Clark -63K, Crawford, Cocker -240, Davis,
Awassa-95
Cocker -240,Clark-63K,Williams,Crawford
Clark-63K,Williams
Cocker -240,Williams
Cocker -240,Davis,Williams,TGX-13-3-2644
Bellessa-95
Davis, Cocker-240, Clark-63K, Williams
Davis, Williams, Cocker-240, Clark-63k
Belessa-95, TGX-13-3-2644, Awassa-95, Crawford
Clark-63K, Davis, Cocker-240, TGX-13-3-2644
Cocker-240, Clark-63K, Williams
Early maturing varieties
Clark -63K, Williams, Davis,
a Potential area for soybean production where more than 5 tons/ha recorded in yield trials. b With supplementary irrigation Seed Production for Highland Pulses
Modes of Reproduction
Pollination is simply defined as the transfer of pollen grains from anthers to stigmas. When pollen
from an anther of a plant falls on stigma of the same flower, the situation is called self-pollination.
When pollen from flowers of one plant is transmitted to stigmas of flowers of another plant, it is
known as cross-pollination. Field pea, chickpea, and lentil reproduce by self-pollination. On the other
hand, faba bean is considered as an often cross-pollinated or partially out-crossing crop with an
average cross-pollination of 35%. Bees facilitate the transfer of pollen from one plant to another in
faba bean.
Relevance of Pollination in Seed Production
Normally, varieties of self-pollinated crops are naturally homozygous while the cross-pollinated once
are highly heterozygous in nature. Because the level of cross-pollination is negligible in selfpollinated crops, their genetic constitution stays stable after varietal release. Farmers may plant the
same seed for several years if the necessary precaution is taken to avoid off-types and mechanical
mixtures. In cross-pollinated crops, however, strict precautions have to be taken to avoid not only
mechanical mixtures but also genetic deterioration due to foreign pollen. This is because crosspollinated crops are liable to out-crossing and, therefore, the rate at which a given variety losses its
identity is directly related to the rate of out-crossing with other variety of the same species. The rate of
out-crossing, in turn, depends on the magnitude of isolation distance between the two varieties and the
presence of pollinators. It is, therefore, advisable to supply farmers with certified seeds of the original
variety more frequently than as in self-pollinated crops.
66
Improved Varieties of Highland Pulses
With the efforts made so far, several varieties of highland pulses have been nationally released from
different centers. List of the currently active varieties in production is given Tables 1a and b.
Varietal description
Varietal descriptions are essential to differentiate one variety from another of the same crop and it is
normally the responsibility of the breeder to describe his varieties. Two varieties are considered
different if they differ in at least one important character, which is clearly and easily recognizable and
consistent over years and locations. Generally, qualitative characters like flower color are more
preferable as descriptors than quantitative characters like the yielding potential of a variety, 1000 seed
weight and plant height. This is because qualitative characters are less affected by changing
environments and, as a result, they are more stable than the quantitative characters. However,
quantitative characters like plant height can also be used as descriptors but it is advisable to use ranges
of possible values over years and locations and not means to describe a given variety using quantitative
characters. As faba bean is a cross-pollinated crop, the number of sample plants on which varietal
description is to be done should not be less than 1000, while lower number of plants could represent
the population in self-pollinated crops. Plants considered for varietal description should be in full intravarietal competition from the central rows of a plot. All observations on the plant (height, number of
stems per plant, growth habit, etc.) and the leave (color, size and number of leaflets per leave, etc.)
should be made at the green pod stage. Observations on the flower (color, number of flowers per node
and length, etc.) should be made when it just opens and on the pod (number per plant, length, width,
shape and curvature, etc.) when fully developed. Observations on seeds should be made shortly after
harvest. The most commonly used morphological descriptors in faba bean; field pea, chickpea, and
lentil are given in Tables 2.22-2.25.
67
Table 2.22. Important morphological descriptors for faba bean
Morphological Descriptor
Plant
•
•
•
Stem
•
•
•
•
Foliage
Leaflet
•
•
•
Raceme
•
Days to flowering
Days to physiological maturity
Flower
•
•
•
•
•
•
•
•
Pods
Seed
•
•
•
•
•
•
•
•
•
•
•
•
Explanations
Height (length from the ground level to the tip of the plant measured at
maturity)
Number of stems (the main stem and tillers above half of the length of the
main stem)
Growth habit (determinate, semi-determinate or indeterminate). Determinate
is with terminal inflorescence, semi-determinate and indeterminate are
without terminal inflorescence.
Number of nodes (across the main stem of the plant starting from the first
flowering node)
Stem color at physiological maturity (light or dark)
Stem thickness (measured as width of one side of stem at mid-height from
ten single representative plants at early podding stage)
Anthocianin color (absence or presence of anthocianin stem pigmentation at
flowering time)
Color before flowering (green, light green or dark green)
Size of basal pair of leaflets at full expansion stage (small, medium or large)
Number of leaflets per leaf (mean of five leaves each of them taken from the
median flowering nodes of five separate plants at full expansion stage)
Number of flowers at the second and the third flowering node (mean of five
representative plants)
Number of days from emergence to 50% of the plants with at least one flower
Number of days from emergence to 90% of the pods have dried
Flower color of petal (white, violet or brown)
Length (cm)
Melanin (spotted or non-spotted)
Number of flowers per node
Number per plant
Angle at maturity of second or third pod bearing node (erect, horizontal
pendent)
Length (mean of 5 random dry pods)
Median width (cm)
Pod curvature at green shell stage (present or absent)
Shape (sub-cylindrical, flattened constricted or flattened non-constricted)
Pod color (light green, green or deep green)
Number of ovules per pod including seeds
Thickness of pod wall (low, medium or high)
Reflectance (matte or glossy)
100 seed weight (average weight of two samples of 100 random seeds)
color of testa immediately after harvest (black, dark brown, light brown, light
green, dark green, Grey, white, violet or yellow)
Helium color (black or color less)
Seed shape (flattened, angular or round)
68
Table 2.23. Important morphological descriptors for field pea
Morphological Descriptor
Plant
•
•
•
Stem
•
•
•
•
•
•
•
Foliage
Leaflet
•
•
•
Flower
•
Days to physiological maturity
Pods
Seed
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Explanations
Height (length from the ground level to the tip of the plant measured at
maturity)
Growth habit (determinate and indeterminate).
Determinate is with terminal inflorescence and Indeterminate is
Without terminal inflorescence.
Number of nodes (across the main stem of the plant starting from the first
flowering node)
Stem color at physiological maturity (light green or dark green)
Stem angulation (erect, semi-erect or fully horizontal)
Number of branches
Texture (ribbed or smooth)
Color before flowering (green, light green or dark green
Size at full expansion stage (small, medium or large)
Number of leaflets per leaf (mean of five leaves each of them taken from
the median flowering nodes of five separate plants at full expansion
stage)
Petiole length (cm)
Arrangement (opposite or alternate)
Number of flowers at the second and the third flowering node (mean of
five representative plants)
Days to flowering (number of days from emergence to 50% of the plants
with at least one flower)
Flower color of petal (white, violet or others)
Length (cm)
Pubescence (absent or present)
Bracts (absent or present)
Number of days from emergence to 90% of the pods have dried
Number per plant
Size (cm)
Type (beaked or non-beaked)
Reflectance (matte or glossy)
Pod color (light green, green or deep green)
Number of ovules per pod including seeds
100 seed weight (average weight of two samples of 100 random seeds)
Seed color of testa immediately after harvest (greenish, dark brown, light
brown, gray, white)
Helium color (black or color less)
Seed texture (rough or smooth)
Table 2.24. Important characters for chickpea
Plant type
Stem
Leaf
Branches
Plant height
Flower
Maturity
Pod
Seed
Any marker
Erect, semi-erect, semi-spreading and spreading
Color, thickness
Color, size (Large, medium, small)
Number of primary, secondary and tertiary branches per plant
In cm, tall, mid-tall, and conventional type
Days to 50% flowering, color and size
Number of days to maturity
Number/plant, number of seeds/pod and size
100-seed weight, roughness, shape and color
For example, simple leaf gene
69
Table 2. 25. Important characters for lentil
1.
For field inspection
Anthocyanin pigmentation
Leaf pubescence
Color of flower standard
Plant height
Time to first flower
Leaflet size as observed at flowering
2.
For sample validity
Seed weight
Background color of seed testa
Pattern on testa
Presence/Absence of stem, leaf and pod
Presence/absence
White, white with blue veins, violet, pink, or rose
cm
Days
Large, medium and small
In g or 100 random seeds
Green, pink, brown, gray, or black
Absent, dotted, spotted, marbled, or combination of patterns
Color of pattern on testa
Olive green, gray brown, or balck
Cotyledon color
Red, yellow or green (Turns yellow with age)
Destructive sampling by removal of testa to see seed cotyledon color
The seed system
There are two possible sources of improved seeds to farmers in Ethiopia. The first source is the formal
seed supply system, which is normally composed of seed multiplication, processing and quality
control and marketing and distribution units. The only organization in the formal seed sector is the
Ethiopian Seed Enterprise (formerly Ethiopian Seed Corporation). The Ethiopian Seed Enterprise has
only a limited capacity to produce the necessary quantity of seed to meet the national demand. The
involvement of private investors in this system is believed to be profitable and helpful as well to
reduce the load on the Ethiopian Seed Enterprise and the scarce government resources. Under the
formal system, breeders are normally expected to generate a small amount of seed called the breeder
seed. This small amount of seed that is multiplied to produce the large quantities of certified seed
needed to satisfy the national seed requirement. The breeder seed is first multiplied to produce the
pre-basic seed, which in turn is multiplied to produce the basic seed. The basic seed is again
multiplied to produce the certified seed, which is sold to the farmers for commercial production.
These different classes of seeds have to meet certain requirements viz. purity, quality, health, and
uniformity before they have to be advanced to the next generation or distributed to farmers for wide
production. The flexibility of these requirements increases as we proceed from breeder to certified
seed. That means, standards are more rigid for the early generations than for the later in the seed
multiplication scheme. Some of these requirements are examined before planting, some when the seed
crop is in the field and the rest require analytical examination in seed laboratory on seed samples
taken from basic and certified seeds in the storage, marketing, and distribution units. Formal seed
systems are usually interested in producing seeds of uniform varieties because certification procedures
are based on genetic uniformity.
The second system is the informal seed supply system where farmers themselves produce seeds and
sell to or exchange with their neighbors. The strengthening of this system with some technical
assistance from seed agency, research centers, and relevant governmental and non-governmental
development organizations is very essential. As relatively higher seed rates per unit area of land are
required for highland pulses, the informal seed system should support the formal seed system to fulfill
the national demand. This could be accomplished through the annual or biannual provision of certified
or basic seeds to progressive farmers with the necessary technical back-ups from breeders, seed
technologists, or extension workers. They should make proper training on seed production and the
70
necessary facilities like mobile seed cleaners available to the farmers until they are both technically
and materially capable to carry out all tasks. Informal seed system also plays an important role in
producing and distributing seeds of farmers’ own developed varieties.
Both formal and informal seed systems can play a complementary role. The formal system may serve
in the production and distribution of improved seeds to the potential farmers while the informal one
may serve resource-poor farmers with low income who cannot benefit from the formal system.
Potential farmers themselves can also use the output of informal seed system when the formal system
is not in a position to make improved seeds available in sufficient amounts. The amount of seed to be
produced must be based on the current demand for improved seeds and seed demand assessment is
very crucial in planning seed production. Normally, the requirements for breeder, pre-basic and basic
seeds depend on the demand for certified seeds by the farming community. Theoretically, the demand
for certified seed in turn depends, among other factors, on the proportion of improved seeds utilized in
a given country, seed rate per unit area and the period required for seed renewal or technically called
“generation control”. Seed replacement rate for self-pollinated crops on average is 4-5 years while it
is 3-4 years for cross-pollinated crops. Assuming that all farmers regularly use improved varieties
based on the standard renewal rates, the annual seed requirement (SR) in quintals per year can be
estimated as:
SR = Total Annual Grain Production Area of a Given Crop (ha) X Seed Rate (kg)
Seed Renewal Rate (Years)
However, seed requirement is a complicated phenomenon influenced by several factors and such
estimation may over simplify the situation. The economic background of subsistence farmers is not
stable and the cropping pattern changes with the actual climatic condition of a given season. In such
cases, the seed requirement of the farmers is rather dictated by external factors like the pattern of the
rainfall and their purchasing power than the actual demand. The stability of market price for grain and
grain products and social services like the credit system are also decisive in farmers’ decision-making.
Experienced professionals who have good knowledge of the up to date social, economic, and climatic
situation should, therefore, assess and predict the demand for seed.
Seed multiplication
Site Selection
Seed production should be undertaken where soils and climatic conditions are favorable for good crop
production. Each variety should be produced in areas of its best adaptation in order to harvest quality
seeds. The accessibility of the seed production field to transport and proximity to seed processing
plants is also equally important in site selection for seed production so that the seeds of the varieties
can be economically produced. The presence of irrigation water and facilities is very important to
avoid risks of moisture shortage at any stage of crop growth. Seed should be produced under uniform
fields to attain full genetic expression and uniform stand of the crops so that an easy identification of
off-types will be possible for rouging. Seed production should not be undertaken on land, which has
grown the same kind of crop of different variety in the previous year. Such fields must be made free
of volunteer plants by allowing an interval of one crop of another species. Even then, land to be used
for seed production must also be made free of volunteer plants introduced any way by hand pulling of
the volunteer plants. Another option is by irrigating the field two-three weeks before planting to
stimulate early germination of seeds of volunteer plants, which then can be easily destroyed by
uprooting, or by under cultivation.
Careful selection of the land to be used for seed production can prevent many problems and
minimizes the work of rouging. It is advisable to avoid planting into a field that is crossed by roads
and a field close to seed warehouses or other installations. It is also equally important that the seed
production field should not be located on the lower level than a field to be planted with a crop that
71
could infest it if the field is sloppy. A few large farms are desirable for seed production than many
fragmented small farms, be it for potential farmers, private investors or state farms. This is because
large farms can be well equipped and easily supervised and managed. If seed production is on
farmers’ fields on contractual basis, progressive and innovative, flexible and experienced, farmers
should be selected for the successful accomplishment. The inherent capacity of the farm, the capacity
of the farmer to irrigate and control pests and diseases and his position within the isolation block
should be considered.
Managing seed production fields
There are no special crop management and protection recommendations for highland pulses seed
production different from grain production. Full genetic expression of the plant type is needed to identify
desirable plants and eliminate off-types and full genetic expression, in turn, is possible under good crop
management and protection conditions. Therefore, the available recommendations should be more strictly
followed in seed production. Highland pulses are sensitive to compacted soil layers as well as surface
compaction. They do not require a fine seedbed as such and hence only 2-3 plowings with the local
plow or one disc plowing followed by two disc harrowing is enough. It is an advantage if land
preparation can start early to encourage weed seeds to germinate so that they can be destroyed in
subsequent cultivation. Generally, timely sowing is essential for optimum yields since late sown crops
can run into the periods of low moisture and heavy aphid infestation in the mid altitude and frost in the
high altitude areas. For faba bean and field pea, main season sowing of mid to third week of June in mid
altitude and last week of June to first week of July in the high altitude areas are recommended based on
the onset of rainfall. Similarly, early August to early September for chickpea and Earl-late August for
lentil are recommended based on the onset of rainfall. Where lodging is suspected, it is advisable to use
10% less fertilizer and slightly less seed rate than the commercial recommendation. This can be can be
achieved by setting the seed rates. Seed rates can be calculated by taking into account the size of the seed,
germination percentage and expected field loss due to birds, soil born diseases and insects. For instance,
the desired plant population per hectare is roughly 500,000 plants for faba bean and 1,000,000 plants for
field pea. Seed rate can be as indicated below:
Seed Rate (Kg/ha) = 10,000 x required plants /m2 x
Number of seeds/kg
% germination
100
x
100
100-expected field loss
For example, given that 50 plants (assuming a spacing of 40cm between rows and 5cm between
plants) of faba bean are required per m2, 3500 seeds make a kilo and the seed has a germination of
85% with an expected field loss of 20%, then:
Seed rate = 10000 x 50 x 100 x 100
3500
85 100-20
= 142.86 x 1.18 x 1.25
= 210.72 kg/ha
It should also be noted that the type of the soil influences the seed rate required in that higher
germination capacity and vigor are required for good population density in heavy soils.
Although the blanket application of 100kg DAP/ ha is recommended under soils of poor fertility groups
for faba bean and field pea, and no significant response to fertilizer application was recommended for
chickpea and lentil, the results of fertilizer trails so far are not consistent as these crops are very sensitive
to environmental changes. Therefore, it is advisable that the seed producer himself should undertake an
accelerated fertility trial to determine the most accurate and site specific fertilizer requirement of his farm.
Weeds can cause substantial losses to highland pulses particularly in faba bean, field pea and lentil
72
production when they are not removed during critical period of competition. The critical period of
weed competition varies from 3 to 8 weeks after crop emergence for these crops. In general, faba bean
is more sensitive than field pea to weed competition. The numerous weeds affecting these crops are
from broad leaves and both annual and perennial grasses. Major weeds in these crops are managed
with hand weeding. Two times hand weeding is very essential for faba bean and lentil one 3-4 weeks
after emergence (WAE) and the second 6-8 WAE. For field pea and chickpea, one hand weeding is
just enough when done in 3-4 WAE. A few insect pests attack faba bean, field pea, chickpea and lentil
as compared to other crops. Major insect pests attacking these crops in the field are aphids
(particularly for field pea and lentil) and pod borer (faba bean, field pea and chickpea). Cypermethrin
(Cymbush 10% EC) can effectively control pod borer at the rate of 150g a.i. ha-2. The spraying should
start with infestation. On the other hand, aphids are controlled by spraying Pirimicarb (Primor
50%WP) at the rate of 0.5 kg a.i. ha-2. Spraying is economical when 35% of the plants are infested.
Faba bean is mainly affected by chocolate spot, rust and black root rot while aschochyta blight and
powdery mildew diseases affect field pea. Chickpea is also affected by black root rot, wilt and
aschochyta blight while lentil is affected by rust, black root rot and aschochyta blight. Most of the
improved varieties are moderately tolerant; therefore, need some protection of the foliar diseases with
fungicides under sever infestation if quality seed is the targeted. Black root rot is controlled by proper
water drainage. Waterlogging aggravates and initiates black root rot development. Therefore, proper
drainage is necessary where camber beds and broad bed and furrows may serve the purpose.
Maintenance of physical and genetic purity
Seed production fields are liable to two types of contamination, i.e. genetic contamination caused by
cross-pollination with other varieties of the same species growing in the field itself or in the vicinity
and mechanical contamination caused by mechanical mixture with seeds of other varieties of the same
crop. The sources of contaminants may include genetic contamination of the crop in the previous seed
production field, mechanical mixture of undesirable seed in the prior production fields or in the seed
lots, volunteer plants resulting from seed left by the prior crop and seed brought to the field by water,
birds, animals, people, or agricultural equipment. The effects of genetic and physical contamination
can be reduced through an appropriate isolation distance, rouging of off-types and avoiding
mechanical mixtures. The isolation distance required varies with the type of crop and the stage of seed
production. In basic seed, an isolation distance of 400m for faba bean, 20m for field pea and 5m for
chickpea and lentil is required from other fields of different varieties of the same crop on each side of
the seed production field to prevent out crossing in faba bean and mechanical mixtures in others.
Similarly, isolation distances of 200m for faba bean, 10m for field pea and 3m for chickpea and lentil
is required in certified seed production (Table 6). However, the distances for faba bean may be
reduced if there are physical barriers between two fields cropped with different varieties of the same
species that prevent easy movement of pollen from one field to another of different variety of the
same species through pollinators. Faba bean production field can also be surrounded with a species
like rapeseed that does not intercross with faba bean but that attracts the same pollinating insects. The
assumption in this case is that the pollinating insects first visit these border plants and lose their
foreign faba bean pollen to them.
Rouging: Plants that are not true-to-type should be removed from the seed production field when
they can be easily identified (example, at flowering). However, off-types should be removed from
faba bean fields before they shed pollen to prevent out-crossing. Off-types can be identified by their
deviation from the genotype such as plant type, size, pigmentation, and flower color. Their size and
their position out of the rows can also identify volunteer plants. The proportion of maximum
permissible off-type plants in these crops is given in Table 6. It is almost equally important to rogue
plants that look diseased and defective.
Mechanical Mixtures: Machinery and equipment should be carefully cleaned during planting and
later at vegetative stages to avoid mechanical contamination by seeds of weeds, other crops or other
varieties of the same species. The threshing floor should also be clean and preferably cemented to
keep contamination by inert matter, weed seeds, and other crop seeds to a minimum.
73
Harvesting and Threshing
Late harvesting may result in shedding and rotting of pods if untimely rain is encountered and in
shattering of the seeds. Therefore, harvesting should be done at the appropriate stages when the leaves
and the pods dry out and when the grain moisture content is significantly reduced. Under our condition
where time of harvesting more or less exactly coincides with the start of the dry season, it is easily
possible to achieve low moisture contents while the crop is in the field.
The crops are not as such suitable for combine harvesting and simultaneous threshing and harvesting
is may be economically performed using manual labor where labor is available and cheap. The crops
should be protected from rain after harvesting while in the field with the use of canvases and
polythene sheets. Faba bean and field pea are indeterminate in growth habit that the lower pods
mature earlier when the upper ones are still green. Therefore, the freshly cut crops should be left on
the ground and after well dried (may be three to four weeks after) the crops should be fed to a
stationary thresher to get clean seeds. The threshing floor (for both formal and informal seed
production) should be clean and preferably cemented to keep contamination by inert matter, weed
seeds, and other crop/variety seeds to a minimum.
Seed processing
Raw seed usually constitutes unwanted components like impurities both in physical and genetic terms.
Therefore, seed processing plant, which includes the process of drying to optimum moisture level for
storage, cleaning and grading, testing for purity and germination, treating for storage pests and seed
borne diseases, and bagging and labeling, is a largest investment in itself. The initial moisture content
of the seed highly influences the viability of the seed and drying must be started within a few hours after
harvesting and threshing and continue until the required optimum moisture level is achieved. Optimum
moisture content reduces the deterioration rates during storage, prevents attack by moulds and insects,
and facilitates processing. Improved seeds of highland pulses should be dried to moisture content of
nearly 9% by thinly spreading on trays or floors in the open sun before storage. Seeds may also be dried
artificially by passing heated or unheated air through the seeds to remove moisture but this method is
more expensive than natural drying although it is necessary especially under a warm, rainy and humid
environments. Seed moisture content is determined as percent water content of the seeds. It is measured
either by drying seed samples in an oven or with the help of moisture testers. The oven method involves
weighing the seed samples and drying them to a constant weight in an oven. The dried seeds are weighed
again and any loss in weight represents the weight of water lost due to drying. Then the percentage
moisture content is estimated as:
Moisture content (%) = W1 – W2 X 100
W1
Where W1 is the weight of the seed sample before drying and W2 is the weight of the seed sample
after drying. The use of moisture meters may require calibrations and correction factors that may need
some technical skill. However, it is the most efficient and faster method. Seeds after being harvested
have to be cleaned to remove inert matter, weed and other crop seeds, other varieties seeds and
diseased and damaged seeds. Cleaning enhances seed quality like purity, germination and health if the
right machines are used and right operations are followed. Seed cleaning based on the differences in
physical properties between the desirable seed and contaminants. Cleaning is possible because seeds
are different in physical properties like size, weight and shape. Sieves mainly made of iron are used
for cleaning and they mainly separate based on the width and thickness of the seeds. There are also air
separators separate seeds mainly according to their weight in relation to the air resistance. Certain
particles (dust, chaff, empty or partially filled seeds, husks) will be transported where as the heavier
seed will fall down through the air stream. Use of graded seeds is also obviously an important
requirement where sowing is done using seed drills and planters. Seeds should be properly graded
before being distributed to the farmers.
74
Seed storage
Seeds should be stored in a dry and cool place free of pests and somehow be protected from absorbing
moisture from the floor. Seeds should be treated with proper chemicals for storage pests but care must
be taken that the treatment of the seed with improper chemicals may impair the ability of the seed to
germinate. The chemical treatment of the seed immediately after harvest and the fumigation of the
store before storage are advisable to keep the quality of the seed in storage. The most important
storage pest in pulses in Ethiopia is the bean bruchids. Currently, the effective control measure
recommended for bean bruchids is the use of Primiphos-methyl (Actelic 50% EC) at the rate of
40g/100kg (6-8 ppm).
Field inspection
Field inspection for basic and certified seeds is performed by seed certification agencies (not by the
producer) in several countries although these processes are at infant stages in Ethiopia. However, the
grower should be trained on the conditions that may lead to the acceptance or rejection of the field
and the seed. Inspectors must have a thorough knowledge of varietal characteristics, common diseases
and weeds and practices and conditions for production of high quality seeds of the crop. Adequate
methodologies of field sampling and specific tolerance levels for contaminants are also important.
Inspections should be made without any previous notification to the seed grower. The main objective
of field inspection is to examine the seed production field and determine its suitability for
certification. Observations are made on whether the crop is grown from an approved seed sources,
grown in a field meeting prescribed land requirements as to the previous crop, in compliance with the
prescribed isolation distances, presence of off-type plants and objectionable weeds and plants of other
crops and diseases. The field should also be thoroughly checked that there are no volunteer plants.
Field inspection must be carried out at the crop development stages when contaminants are clearly
identified.
Basic seeds and certified seeds have different quality standards, which are more rigid in basic seeds
for maximum permissible off-types, isolation distance and maximum permissible percent of other
crop seeds (Table 6). Three inspections in case of faba bean (one before flowering, one at flowering
and one before or during harvesting) and two in other crops (one each before and during flowering)
are recommended. Inspection before flowering is done to assure proper isolation distance and
presence of volunteer and off-type plants while the one during flowering is done to see the presence of
off-types with different flower colours as described for the variety. Inspection is made before or
during harvesting to assure whether the seed maintained its originality as described for the variety.
Field inspection can be accomplished in two steps. First, the inspectors are required to undertake the
so-called “Field Overview” where by the inspectors walk through the field so that they can see the
general condition of the whole field. Rough estimation of the field size and shape should be taken
before making the inspection. If the field is roughly regular in shape, the standard patterns of walking
through the field as shown in Fig. 3 should be followed for the field overview. However, the
inspectors themselves should modify the standard patterns of walking for an irregularly shaped field
in such a way that the modified patterns of walking fairly represent the whole field. The inspector
should get into the field from any side, so long as the standard pattern of travel can be seen. He should
walk through the field in such a way that the sun’s position helps clearly observe the general condition
of the field. The first and foremost requirement in seed production is that the seed to be multiplied
must be from an officially released variety. The inspector should identify the variety actually grown in
the field. In case of doubt, he has to carefully compare the morphological characters with the variety
descriptors to assure varietal identity. If the varietal identity does not confirm to the varietal
descriptors, it can be automatically rejected. In case most of the crop (one-third or more) is lodged and
is difficult or impossible to evaluate it properly, the whole field may be rejected without further
inspection. However, this principle may not hold for prostrate crops like field pea. Observations are
also made on isolation distance, crop uniformity, crop condition, disease infection and cultural
practices and yield estimates. The second step in field inspection is to determine the number of
statistically representative plants from the seed production field, called the “Field Inspection Sample”.
75
Normally, given the standard for tolerance level to each contaminant, the Field Inspection Sample
should include 3 times the number of plants in which 1 contaminant is allowed. Since different
generations have different standards for different types of contaminants (Table 6), the size of the Field
Inspection Sample is also expected to vary with contaminant and seed class. However, to simplify the
inspection, one standard Field Inspection Sample Size is suggested to be used for all contaminants in
each seed class.
The size of this standard Field Inspection Sample is determined by the strictest standard for each seed
class. Suppose that you are inspecting faba bean basic seed field and after making the field overview
successfully, you want to determine the sample size for more detailed inspection. The strictest
standard for faba bean basic seed production is 0.1%, which is the value for maximum permissible
percent of off-type plants. This standard allows 1 contaminant plant in 1000 desired plants. The
standard field inspection sample size in this class of faba bean seed production field is suggested to be
3000 (1000 x 3) plants. To assure that the Field Inspection Sample more accurately represents the
total field quality, the whole field inspection sample is divided into 5 or 6 smaller areas called the
Field Counts, randomly located in different parts of the field. This number of field counts has been
statistically demonstrated to represent field quality accurately, if they are located in different parts of a
uniform field. Field Counts are calculated simply by dividing the total Field Inspection Sample size
by 5 or 6 depending on the number of field counts selected (5000/5 = 600 plants per field count or
3000/6 = 500 plants per field count). If the number of plants per unit area is known, these 600 or 500
plants can easily be translated into an area to be inspected for each field count. The higher the number
of plants per unit area, the smaller will be the field inspection sample and the field count sizes (m2).
Once the field count size is determined, the site of the first field count should be randomly selected
and the appropriate distance between subsequent field counts should be set in such a way that they are
randomly located in different parts of the field.
Sometimes it is may be proved that the field meets the standards and is automatically accepted, or
does not meet the standards and it is automatically rejected. However, field counts should be taken
and rates of occurrence of contaminants must be recorded any way. In each of the five field counts,
the inspector should carefully examine all plants and counts and should take records of all
contaminants separately until the field and the five or the six field counts have been covered. When
field inspection is completed, the total number of plants of each contaminant in all field counts should
be added and the proportion of contaminants should be determined. If the proportion of each
contaminant plants is less than the rejection level, the field is accepted for that particular factor. If
more contaminant plants than the tolerance level are found, the field is rejected or correction measures
like rouging should be carried out after which the field must be re-inspected. When the level of the
contaminant plants is exactly equal to the level of tolerance, an additional 5 or 6 field counts should
be taken to confirm acceptance or rejection.
Records should also be made on situations that are not specified in the standards. If there are pockets
with excessive contaminants, non-uniform and different from the rest of the field, they should be
marked off and recorded with a map on the field inspection report for rejection or rouging. The
number of weed plants whose seed is difficult to eradicate and plants diseased with pathogens but not
specified in the standards should be recorded. Areas within the isolation distance should be examined
in all sides of the field for volunteer plants or for fields that may contaminate the seed crop. It should
also be confirmed that roadways and field edges are free of plants, which may cause contamination at
harvest. If isolation is not sufficient, it must be corrected if possible or the field should be rejected.
Seed Inspection
Seed has to satisfy certain analytical requirements of seed quality control measures, which include
genetic and physical purity, germination, freedom from weed seeds and seed borne diseases and
optimum moisture content. Seed inspection is again performed by seed certification agencies (not by
the producer) for basic and certified seeds. However, an internal seed quality control system is also
76
very important by all seed producers. A lot number should identify seeds coming from each field from
one another and if harvesting could not be undertaken under the same condition due to bad weather, it
is advisable to have even sub-lots. Systematic moisture determination at time of harvesting, during
drying, and after drying is needed. Purity and germination tests are also equally important. The main
objective of seed inspection by seed agencies is again to examine the seed and determine its suitability
for certification. Observations in this case are made on presence of objectionable weed seeds, other
crop seeds, seeds of other varieties of the same crop, seed borne diseases, the level of inert matter and
seed moisture content. It is important to confirm that the seed maintained its originality as described
for the variety. In this case, too, standards for basic seeds are more rigid for some parameters
(maximum permissible percent of other crop seeds and maximum permissible percent of other
variety’s seeds) as compared to certified seeds. Analytical tests are normally undertaken on a bulk of
representative samples taken randomly from the seed lot. If the seed is in a single bag, samples should
be drawn using a trier at least from three places of the bag and should be bulked. If there are a number
of bags, at least one sample should be taken from each bag and be composited. The bulk sample
should be thoroughly mixed and sub-divided into the so called a working samples by repeated
quartering. The weight of a working sample may reach 100g-500g depending on the type of crop and
the level of accuracy and the number of replicates desired.
Contamination of 0.05% (on weight basis) by seeds of other crop species is permitted in certified
seeds of faba bean and field pea. As faba bean is partially open-pollinated, contamination by other
variety of the same crop is not permitted in basic seed, as it will deteriorate the genetic performance of
a given seed even within a few generations. The seed should be free of inert materials such as sand,
stones, straw, soil particles and defective seeds that are broken, rotten, insect attacked, shrivelled and
not able to germinate. A broken seed larger than half of the normal seed size is not considered
defective if the embryo is not damaged. The maximum total amount of permissible contamination by
inert material and defective seeds in basic and certified seeds is 2%. It should be free from
objectionable weed seeds (0%) and seed borne diseases and should be dried to optimum moisture
content of 9% (Table 6). Seeds contaminated with pathogens should be thoroughly treated with
proven disinfectants or protectants before distributing to the farmers. Seeds should be tested for
important seed-borne diseases like chocolate spot and aschochyta. The information on quality control
tests should be strictly considered to decide whether seed treatment is needed and the seed rates for
the optimum population density.
Generally, purity (genetic or physical) is calculated on the weight basis as:
Purity (%)
=
Weight of pure seed
Total weight of the working sample
=
Weight of pure seed
Weight of (pure seed +seeds of other
varieties + seeds of other Crops +
weed seeds + inert matter)
X
X
100
100
The seed should have a high germination percentage (minimum of 85% for faba bean, field pea and
chickpea and 75% for lentil) and real value, which are estimated as follows:
Germination (%) =
Real value (%)
Total number of seeds germinated X 100
Total number of seeds planted
=
Purity (%) X Germination(%)
100
77
Seed Certification
Seed certification is made by seed certification agencies to ensure the purity, freedom from weed and
other crop seeds and seed-borne diseases and good germinability. Seed certification is done based on
field and seed inspections, the ultimate goal being to achieve seeds with the highest possible real
value. Field inspection verifies the seed source, varietal identity, previous cropping, isolation distance,
off-types, weeds, other crops, other varieties, diseases, etc. Seed inspection at the processing plant and
in the seed store verifies for seed standard. Seeds below the standard are rejected and are excluded
from the market. The producer himself should normally request field and seed inspections and
certification preferably in advance of the sowing of the seed crop. The seed is rejected if the
requirements are not satisfied. However, if the seed meets the prescribed seed certification standards,
the certifying agency provides the label that assures the seed is certified. Seed certification ensures
that the seed sold to the farmer is of the indicated variety, sufficiently pure, of good germination
capacity and diseases free. Seeds should be bagged in bags of appropriate size for distribution and
each bag should be labelled and sealed to prevent adulteration. The label should contain the following
information:
•
•
•
•
•
•
•
•
•
•
Kind of seed;
Name of the variety;
Percent purity;
Percent germination;
Date of germination test;
Percent weed seed;
Percent inert matter;
Name and address of the seller;
Period of validity of the certification; and
Any other information pertinent to the seed
Recommended field practices to be followed in seed production and analytical seed quality
requirements to ensure quality of basic and certified seeds in highland pulses are shown in Table 2.26.
78
Table 2.26. Recommended field practices to be followed in seed production and analytical seed quality requirements to ensure quality of
basic and certified seeds in highland pulses
Parameter
Maximum permissible off-type plant (%)
Maximum number of field inspection
Number of Objectionable weed plants
Minimum isolation distance(m)
Minimum percent of pure seed (on wt.
Basis)
Maximum permissible percent of other
crop seeds (on wt. Basis)
Maximum permissible percent of other
Variety’s seeds (on wt. Basis)
Maximum permissible percent of inert
matter (on wt. basis)
Moisture content maximum (%)
Minimum Germination including hard
seeds (%)
Minimum real value (%)
Weed seeds maximum (%)
Faba bean
Basic Certified
seed
seed
0.1
0.2
3
3
nil
nil
400
200
95
95
Field pea
Basic Certified
seed
seed
0.1
0.5
2
2
nil
nil
20
10
98
98
Chickpea
Basic Certified
seed
seed
0.1
0.2
2
2
nil
nil
5
3
98
98
Basic
seed
0.1
2
nil
5
98
Lentil
Certified
seed
0.2
2
nil
3
98
nil
0.05
nil
0.05
nil
0.05
0.1
0.2
nil
5/kg
0.1
0.5
0.10
0.20
5/kg
10/kg
2
2
2
2
2
2
2
2
9
85
9
85
9
85
9
85
9
85
9
85
9
75
9
75
81
nil
81
nil
83
nil
83
nil
83
0.05
83
0.10
74
0.1
74
0.2
2.3. Oil Crops
Among the limiting factors of groundnut and sesame production and productivity, diseases play a
major role. The bacterial leaf spot caused by Xanthomonas sesame or Pseudomonasa sesame is the
major disease and cause significant damage to sesame. Phyllody, root and stem rot, wilt and powdery
mildew are minor in importance. In years of severe infections, bacterial blight can even devastate the
crop in humid and high rainfall areas of the country. Among insect and mite pests recorded on sesame
and groundnuts termites were reported to be important in Wollega, Hararghe, Gamo Goffa and the
Middle Awash. Sesame seed bug (Elasmolomus sordidus) is a serious pest in the northwest, while
jassids, the African bollworm and thrips are becoming important pests of groundnut in all areas of the
crop is grown. In storages, webworm and different species of beetles were reported to be important on
both crops.
Disease management
Sesame
The crop is attacked by a number of fungal, viral, bacterial mycroplasma like organisms and
nematodes, which limit its production. Bacterial leaf spot disease, which is caused by Xanthomonas
sesame Sabet and Bowson, or Pseudomonasa sesame Malakoff, is the most important one that can
even devastate sesame under favorable environmental conditions.
79
Table 2.27 Economically important diseases of sesame in Ethiopia
Common name
Blight
Blight
Phyllody
Wilt
Wilt
Root rot
Root rot
Leaf spot
Leaf spot
Leaf spot
Powdery mildew
Pathogen
Pseudomonasa sesame
Xanthomonas sesame
Micoplasma like organism (MLO)
Fusarium oxysporum
Verticillium sp.
Fusarium oxysporum,
Rhizoctonia sp.
Alternaria sesame
Cercospora ssesamicola
Cylindrosprium sesami
Oidium sp.(imperfect stage)
Erysiphe sp. (perfect stage)
Status
Major
Major
Major
Minor
Minor
Minor
Minor
Minor
Minor
Minor
Minor
Bacterial blight
The bacterial leaf spot Pseudomonas sesame is of worldwide distribution and is probably the major
cause of yield reduction whenever it occurs in sesame plantings. It is most damaging under conditions
of high rainfall and high humidity, but less damaging when sesame is grown in arid areas under
furrow irrigation, but when flood-irrigated, standing water can encourage the spread of the disease.
In Ethiopia, both pathogens (Xanthomonas and Pseudomonasa sesame) may occur together or
separately and can cause considerable yield reduction or complete crop failure in years of suitable
climatic conditions for disease development. The disease is widely distributed in the country but it is
often severe at Didessa, Fincha, Asosa, Dabus, Bisidimo, Babile, Gambella, Meiso, Tedele, and Kobo.
At present, it is most sever at Loko, Guten, Gambella, and Pawe; moderate at Humera, Metema and
Babile while low at Werer.
Control measure
Since transmission is mainly through the seed it is often difficult to control bacterial blight after
infection has already taken place in the field. To manage the disease use of resistant varieties,
quarantine, cultural, chemical, and resistant varieties were practiced in many parts of the World.
Host plant resistance
Evaluation of sesame genotypes for bacterial blight resistance started since 1981 and continued in an
on and off rhythm until 2005 at different places. Through this long years research at Werer, Babile,
Loko and Pawe varieties E, Venzuela 44, Ex-Tuvan, Zira, Morada, Abusanduk and selections such as
SPS 202- 297, 202-304, 202-349, 202-514, 207-958, Acc. 214-254, B/M # 06, B/M-09, B/M-25,
B/M-28, B/M # 51, PGRC/E 111-504, AccNo.202-514, PGRC/E 202-099 and SPS Bako #5 (81)(82);
E.W. 010.(1), E.W. 002. (5), W.W 001 (5) and E.W. 013.(8) were found moderately resistant.
Physical method
Hot water treatment on bacterial blight severity and disease incidence, germination percentage, and
plant height was studied at Werer. Germination percentage of seeds was significantly affected when
water temperature passed above 60oC. Seeds treated in 65oC water for 10 minutes germinated only
20%, while those treated by above 65oC did not germinate at all. Therefore, sesame seeds could be
treated in 52oC for 10-12 minutes to control seed borne bacteria. However, to get maximum benefit
from the seed treatment re-infection at field level should be avoided or minimized.
Chemical method
Four levels of streptomycin concentration (250, 500, 750, 1000 ppm) were evaluated to determine the
effective streptomycin concentration in controlling bacterial blight. It was found that soaking sesame
80
seeds in 1000-ppm streptomycin solution for 30 minutes reduced blight infection by 75% and
increased yield by 23.6%.
Phyllody
Phyllody is another important disease of sesame that causes considerable yield reduction when
conditions are favorable for its development and spread. However, for this important disease there is
no directly recommended control measure, but managing jassid (Orosius albicnatus) that transmit the
diseases is considered important in minimizing the risk.
Other diseases
The remaining diseases such as wilt, root rots, leaf spots, leaf curl, and powdery mildew are sporadic
in appearance and minor economically. Therefore, there is no remedy or control measure studied for
these groups of diseases in Ethiopia so far.
Groundnut
Early and late leaf spots and rust are important diseases of groundnut. The leaf spot diseases cause
yield reduction of 65% in areas with high rainfall. Diseases with minor economic importance include
root rot, wilt, stem rot, kernel rot, crown rot, leaf blotch, different leaf spots, leaf curl viral diseases,
and bunchy top.
Table 2.28 Economically important groundnut diseases in
Ethiopia
Common name
Early leaf spot
Late leaf spot
Rust
Gray mold
Storage mold
Storage mold
Wilt
Pepper spot
Root and crown rot
Root and crown rot
Root rot
Leaf spot
Leaf spot
Leaf spot
Stem rot
Stem rot
Phyllody
Peanut mottle
virus/rosette?
Pathogen
Cercospora arachidicola
Cercospora personata
Puccinia arachids
Botrytis sp.
Aspergillus niger
Aspergillus flavus
Fusarium sp.
Alternaria sp.
Aspergillus sp.
Rhizoctonia sp.
Rhizopus sp.
Cladosporium sp.
Penicillium sp.
Phomopsis sp.
Sclerotium rolfsi
Aspergillus niger
MLO
?
Status
major
major
major
minor
minor
major
major
major
minor
major
minor
minor
minor
minor
minor
minor
minor
major
To control groundnut diseases several variety screening and very few fungicide testing trials have
been carried out for the last 30 years in major growing areas of the country. Results of these studies
are presented here under.
Host plant resistance
On groundnut, several genotype screening works have been conducted at Abobo, Babile, Bisidimo,
Loko, Pawe, and Werer for leaf spot and rust resistance. These diseases infected all tested genotypes,
however, the level of resistance to leaf spot and rust varied significantly. Most of the genotypes tested
81
showed a high disease severity and yield was not collected from most plots due to heavy defoliation
of leaves in different years depending on climatic conditions. However, there were genotypes with
varying degree of resistance to leaf spot and rust at tested sites.
•
•
•
The variety screening trial conducted for rust resistance identified genotypes such as Chalambana, PI315608, PI-298115 moderately resistant;
For leaf spot, at Babile genotypes ICG 270, ICGV 863457, ICG 2917, PI 381622 and IGFDN-29 were
found resistant while ICG 9224 and Oldhalle were moderately resistant however, pod yields could be very
low (9-17q/ha). At Pawe genotype ICG-9224, ICGV 86347 and ICGV-86347 were moderately resistant. At
Werer and Loko genotypes ICG-7273, ICG-9261, PI-381622, ICG-2530, and ICG 7476 proved to be
resistant to leaf spot diseases again. Generally, genotypes ICG-270, ICG 2917, ICG 7476 and PI-381622
was resistant to leaf spot and rust over years and locations but yielded very low at both locations; and
Low level of mold (Aspergillus) contamination was recorded on genotypes ICG-2519, ICG-9088, NC-4X
and J 11.
Chemical control
•
•
Groundnut rust can be controlled by spraying Benlate 50% WP (1 gm/liter water); and
Spraying chlorothalonil 85% WP at the rate of 3-3.5 kg product per hectare at 15 days interval from disease
onset controlled leaf spot effectively.
Insect Pests Management
Sesame
A wide range of pests attack sesame around the world, in Ethiopia however, only the sesame
webworm (Antigastra catalaunalis), seed bug (Elasmolomus sordidus), gallmidge (Asphondilia
sesami), green vegetable bug (Nezara viridula) grasshoppers, African Bollworm, (Helicoverpa
armiger), and crickets have been recorded. They become more serious as crop acreage expands and
mono cropping is practiced largely. Among insect pests attacking sesame nowadays only the sesame
seed bug, webworm, and gallmidge are causing serious problems. In the past, only seed bug was
causing economic problems while webworm and gallmidge were minor pests.
Table 2.29. Insect and mite pest recorded on sesame
Scientific name
Polyphagotarsonemus latus (Banks)
Podagracia spp. (Jacoby)
Oryzaephilus surinamensis
Tribolium castaneum
Conoderus vespertinus F
Epicauta albovittata (Gestro)
Common name
Yellow tea mite
Flea beetle
Saw toothed grain beetle
Red flour beetle
Stripped blister beetle
Status
minor/moderate
major
minor
minor
minor
minor
Gonocephalum simplex (Fabicius)
Elasmolomus sordidus (Fabicius)
Agonoscelis pubescens (Thunberg)
Nezara viridula (L.)
Myzus persicae (Sluzer)
Empoasca spp. (Jacobi)
Helicoverpa armigera (Hubner)
Antigastra catalaunalis (Duponchel)
Aiolopus simulatrix (Walker)
Dusty brown beetle
Sesame seed bug
Cluster bug
Green stink bug
Green peach aphid
Jassid
African bollworm
Sesame webworm
Grasshopper
minor
major
minor/ moderate
minor/moderate
moderate/ major
minor /moderate
minor
moderate/ major
minor/ moderate
82
Sesame web worm (Antigastra catalaunalis)
Antigastra catalaunalis originates from the Mediterranean sub-region and India. It is a serious pest on
sesame in the drier tropical and subtropical regions of the Old World and has recently invaded the
New World. Webworms are expected to follow the cultivation of sesame and become a pest with a
cosmopolitan distribution.
Biology: Adult moths have a wingspan of 20-21 mm. The forewings are triangular with a clearly
pointed apex. The ground color is light orange-brown. There is no particular wing pattern on the foreor hind wings. The veins on the forewing are more pronounced than the membrane between them.
The lifespan of the adult varies from 5-9 days in males and 5-11 days in females, and is dependent on
locality and season. Females lay eggs singly on the lower surface of tender leaves and on the apex of
twigs, flowers, and pods at night. The larvae reach about 18 mm in length. The head and prothoracic
shield is dark brown. The larvae are light brown to green with thin, longitudinal, pale-red lines. There
are five larval instars. Young larvae are less frequent on pods than on other plant parts. The larvae
feed externally by making a loose web, which sticks several leaves together. The larvae feed on leaves
and young shoots. Excreta (frass) remain between the leaves and the loose web. At a later stage, the
larvae infest the sesame fruit capsule making an entrance hole on the lateral side and feeding on the
seeds; they leave excreta on the seeds. The pupae are found in the soil near dead host plants. Plants
grown under shade are more susceptible to infestation by webworm than those grown in the open.
Economic impacts: A. catalaunalis is a serious pest of sesame. It infests flowers more than pods,
but can cause up to 53% seed loss in pods. The economic injury level for the application of carbaryl
and endosulfan was calculated as the infestation of 2-3% of plants, 32-77 days after sowing in India. Control
Cultural control: There is a significant correlation between moth abundance and the wet and dry
seasons. Timely thinning of the plants to 10 cm between plants and 40 cm between rows is
recommended.
Chemical Control: A wide variety of chemicals has been used to control webworm, which include
endosulfan, malathion, deltamethrin, carbaryl dimecron, and lamdacyhalotrine, pirimiphos-methyl,
and thuracide.
Sesame seed bug
Sesame seed bug Elasmolomus sordidus synonyms Aphanus sordidus or A. littoralis has a wide
distribution range in Africa and Asia. It has been recorded from West Pakistan, India, China, Senegal,
Malawi, Somalia, and the Sudan. In 1977, it is reported as a major pest of sesame in North West
Ethiopia. Sesame seed bug was reported to attack the seeds of sesame, and groundnuts, but has also
been recorded feeding on grasses, sedges, cotton and bananas in Nigeria.
Sesame seed bug was reported long ago however, its prevalence and damage was restricted to North
Western part of the country and it is so important only in years of outbreaks. In the Sudan, Kordofan
Province, the pest is a serious local pest when it appears in large numbers at harvest time. In Ethiopia
no records of outbreak could be cited, but as an informal survey result indicate the pest is well
established at Humera and Metema areas and its seriousness varied from year to year depending on
the topography and climatic conditions, such as rainfall and humidity.
Damage: Sesame is attacked in the field when pods are open, after the plants have been cut and put
together in stacks for drying and in warehouses. The pest incurs both physical damage (weight loss,
color change, and shape) and quality loss (oil yield, odor, and change of protein content). The nymphs
and adults suck the oil from the seeds, which shrivel and become bitter and worthless. Infested seeds
are poor in germination and loose vigor.
83
Management
Cultural
•
•
•
•
•
•
•
Sanitation (removal or burning of the stalks);
Destruction of weeds that could harbour the pest;
Drain standing water;
Harvest early when pods/stem are yellow;
Thresh/shake as early as possible when pods open fully;
Store in air thight bugs and well protected ware houses; and
Keep clean around the store and seal all openings Chemical: There is no registered insecticide for the control of sesame seed bug in Ethiopia,
However, farmers at Humera and Metema area spray Malathion 50% EC and Ethiosulfan 35% EC
one to three times at the base of sesame stalks in stack. Dusting the base of stack and the soil around
them with Ethiolathion 5% Dust, DDT and Carbaryl 85% WP is well prcticed. In the Sudan γBHC is
used for dusting the base of stack and the soil around them at harvest time. In India Acephate 600
g/ha, Triazophos 500 g/ha and Neem Seed Kernel Extract (NSKE 5%) applied 75 and 90 days after
planting were found effective. Fenitrothion and Diazinone could also be used as foliar spraay before
harvest.
Sesame gall midge
The sesame gall midge (Asphodilia sesami) is distributed from India to Africa and Asia. Gall midge
was minor pest of sesame in Humera area, but now a days it is becoming key pest as mono cropping
of sesame is well established in the area due to its high market value.
Damage: Cause extensive damage. Eggs are laid in ovaries of flowers and the gall begins to develop
before the petals wither. Fruits may shed after attack and or they may develop into large galls inside
which the fly maggot feeds and eventually pupates. In Uganda, in the Lango area the damage in one
season was estimated to be 20-30% of the potential crop. Late sown varieties in Thailand are also said
to be more subject to attack by the midge.
Biology: The adult is mosquito like fly with long antennae and the maggot is a grayish-cream, some
3-4 mm in length. The orange to reddish maggots feed inside young developing capsules and causes
their malformation into globular, seedless galls. Flies have only one pair of wings and the mouth parts
are sponging type. With these stamp like mouthparts adult flies are not able to injure plants. They
usually feed on nectar and other sweet substances such as honeydew and pupate in cocoon in the soil.
The larvae, called "maggots" are the damaging stage. They are head and legless and have mouthparts,
which consist of a pair of dark colored hooks, used for chewing. According to their feeding habits,
maggots can be classified as fruit borers (fruit flies), stem and shoot-borers and leaf minors.
Control: It can be controlled by Dimethoate but application may be required every 10-14 days
during the flowering period in those areas where it occurs annually or elsewhere in a season of above
average infestation. Apply Diazinon, Malathion, Phosphamidon (Dimecron), Bait sprays Malathion,
Dipterex: Add to the insecticide/water mixtures protein hydrolysate, for example, Buminal or fish
protein soluble as attractants. Usually the treatment of every second plant or row is sufficient. Apply
as a coarse droplet spray. If protein is not available use sugar to prepare the bait (but all the plant
should be treated) and repeat every week.
Sesame jassid
Sesame jassid, Orosius orientalis is a serious pest of sesame especially through the transmission of
sesame witches' broom disease (phyllody). It is also observed in most sesame growing areas of
Ethiopia. Plants developed phyllody do not bear seed thus causing 100% yield loss. Detection and
inspection: - Visual inspection and manual searching of plants will reveal the presence of adults and
nymphs. Sticky traps and sweep-nets could also be used to monitor populations.
84
Chemical control
•
•
•
Cypermethrin, deltamethrin and fenpropathrin were effective in maintaining the plant population and in
regulating the disease in India;
Foliar applications of a mixture of carbaryl and parathion-methyl considerably reduced disease incidence
and increased yield; and
Monocrotophos also prevented the spread of phyllody, and a soil application of phorate followed by sprays
of systemic insecticides was found to control both leaf curl virus and phyllody.
Green peach aphid (Myzus persicae)
It sucks the juice from the leaf and young stems.
Control
•
•
•
Field sanitation;
Use of natural enemies (see ABW); and
Chemical spray of marshal, deltanate, or dimethoate and Suprathion
Storage Pests
Different storage beetles could be managed by applying fenithrithion at 30 g/t, baythion at 100 g/t,
Aluminum phosphide at 5 tablets, and pirimiphos-methyl at 300 ppm. Similarly, Storage webworm
could be managed by applying Aluminum phosphide, Fenithrithion, and Pirimiphos-methyl at the
above-mentioned rates.
Groundnut
During its development, curing and after harvest groundnut is attacked by a number of insect pests
Among pre-harvest insects African bollworm, lesser armyworm, cotton leaf worm, stripped blister
beetle, termite, jassid, aphid, and pollen beetle presume primary importance. Insect and mite pests
recorded on groundnut are presented (Tables 4). In the past termites were reported to be important on
both sesame and groundnut only in Wollega area. Nevertheless, now the problem has become
expanded to other areas such as Hararghe, Gamo Goffa and the Middle Awash. Sesame seed bug
(Elasmolomus sordidus) is a serious pest in the northwest, while jassids, the ABW, and thrips are
becoming important pests of groundnut in all areas where crop is cultivated. In storages, webworm
and different species of beetles were reported to be important.
Table 2.30. Insect pest recorded on groundnut in Ethiopia
Scientific name
Epicauta albovittata (Gestro)
Mylabris spp. (Reiche)
Gonocephalum simplex (Fabicius)
Bemisia tabaci (Gennadius)
Aphis craccivora (Koch)
Empoasca spp.(Jacobi)
Common name
Stripped blister beetle
Pollen beetle
Dusty brown beetle
Whitefly
Groundnut aphid
Jassid
Status
moderate to major
moderate to major
minor
minor to moderate
moderate to major
minor to moderate
Nezara viridula (L.)
Odontotermes anceps (Sjostedt)
Helicoverpa armigera
Spodoptera littoralis
Spodoptera exuga
Aiolopus simulatrix (Walker)
Thrips spp
Green stink bug
Termite
African bollworm
Cotton leaf worm
Lesser armyworm
Grasshopper
Thrips
minor
moderate to major
moderate to major
moderate to major
moderate to major
minor to moderate
minor to moderate
85
Mangement
To manage groundnut insect pests it is very important to know the behavior and habitat of each
species. The above listed important pests fall in two distinctly different habitats (foliage and soil),
which are of paramount importance in the design of management strategies. Foliage inhabiting
arthropods can be divided into two groups according to method of feeding and characteristic injury
inflicted to the peanut plant. These are foliage consumers which remove foliage with mandibulate
mouthparts (boll and leaf worms, grasshoppers, and beetles); and intracellular feeders (jassid, aphid,
trips, whitefly and spider mites). Foliage consumers damage groundnut by removing foliage and thus
diminish photosynthetic substrate. As a result significant yield loss can occur if heavy infestation
appears at early stage of crop development. The intracellular feeders damage by removing cellular
contents or indirectly by injecting toxic secretions and vectoring numerous plant diseases. Damage of
these arthropods (jassids, aphids, thrips, and spider mites) can result in significant yield loss
depending on the particular pest species, plant growth stage attacked and physical environment.
Lesser armyworm (Spodoptera exigua) or Laphygma exigua
Host range
S. exigua is a polyphagous pest, which attacks most kinds of field crops. It is most commonly
recorded from grasses and from maize, rice, sorghum, cotton, tobacco, groundnut, broad bean,
sesame, jute, citrus, sugar beet, lucerne, various vegetables, and weed species.
Symptoms: Young larvae feed on the under surface of leaves where they eat the lamina but often
leave the upper epidermis and larger veins intact. Larger larvae make irregular holes in leaves and
fully-grown larvae devour foliage completely, leaving only major veins.
Control: Recommended insecticides for spodoptera spp. include Fenvalerate, Carbaryl, Methomyl,
Chlorpyrifos, Malathion, Methyl parathion, Permethrin and lamba-cyhalothrin.
Leaf worm (Spodoptera littoralis)
Economic impact
•
•
•
•
S. littoralis is cosmopolitan insect pest;
It can attack numerous economically important crops throughout the year;
Larvae first select young folded leaves for feeding, but in severe attacks, leaves of any age are stripped off;
and
Sometimes, even the ripening kernels in the pods in the soil may be attacked.
Chemical Control
•
•
•
•
Durusban 24% EC/ULV @ 2 lt/ha;
Carbaryl 85% WP @1kg/ha;
Decis 2.5% ULV @ 2 lt/ha; and
.Mitac 20% EC/ULV @ 2 lt/ha
Mechanical control
•
Hand picking of the egg mass
African bollworm (Helicoverpa armigera)
ABW is a polyphagous insect pest feeding on leaves and flowers and causing great yield loss to crops.
It can cause up to 12% yield reduction
Cultural control
•
•
•
Closed season;
Field sanitation; and
Effective land preparation
Chemical control
•
Thiodan/Endosulfan 25%ULV 3 liters/ha;
86
•
•
•
•
Thiodan/Endosulfan 35% EC 2.5 liters/ha;
Katare/Lambda cyhalothrin 0.8% 2 liters/ha;
Decis/Deltamethrin-2 liters/ha; and
Curacuron/selecron- 2 liters/ha
Aphid (Aphis craccivora)
•
•
•
•
A. craccivora is a major pest of groundnut, cowpeas, pigeon peas and a range of other crops worldwide;
Economic impact can result from direct feeding, but more importantly, due to virus spread by the aphid;
It is a vector of about 30 plant viruses, such as groundnut mottle and groundnut rosette; and
Direct feeding damage on groundnuts by large numbers of aphids can result in partial sterility of plants.
Symptoms
•
•
•
Groundnut plants take on a bushy appearance due to attack by A. craccivora;
Infection with rosette virus; and
Rosette may take two forms
o
o
o
Chlorotic rosette (white patches with green veins on young leaves and short internodes) and
Green rosette (darker appearance with stunting of leaflets and branches).
Whole plant: external feeding; dwarfing. Leaves show abnormal colors; honeydew or sooty mould; necrotic
areas.
Detection: On groundnut, very young rolled up leaves of seedlings should be examined for nymphs
early in the season. Management
Cultural
•
•
•
Early and dense sowings, early sowings allow plants to start flowering before aphids appear, while dense
sowings provide a barrier to aphids penetrating in from field edges;
Sanitary measures are important within crops and between seasons to prevent the spread of viruses for
which A. craccivora is a vector; and
Virus-infected plant material should be removed after harvest and any volunteer plants or weeds that harbor
viruses should be destroyed.
Chemical
•
•
•
•
•
•
Most major groups of insecticides have been used against this insect pest, including chlorinated
hydrocarbons, organophosphates, carbamates and pyrethroids;
Control in groundnuts must be very effective between germination and the 40th day;
Systemic insecticides with satisfactory persistence through this growth stage are preferred;
Systemic insecticides will kill aphids effectively, but they may still have time to feed and transmit virus
before dying;
In such circumstances, it may be more effective to control aphids on wild hosts on which they feed before
dispersing to crops; and
Contact insecticides such as marshal 25% ULV 2 liters/ha, Polo 500 SC 1 liter/ha, Deltanate 200 EC/ULV 2
liter/ha, Suprathion 35% EC/ULV 2 liter/ha and Dimethoate 40% ULV 1.5 liter/ha give good control.
Biological control: Coccinellid, lacewing, and syrphid fly are good predators of aphids
Thrips (Caliothripsspp.)
Primary hosts include onions, garlic, leek, groundnut, legumes, soybean, grass pea, moth beans, mung
bean, black gram, Sesame, and sorghum.
Jassid (Empoasca lybica)
Behavior
• When touched nymphs move sideways or adults jump;
• Commonly located on the upper canopy of the plant; and
• During day most of jassids are found on the underside of leaves andvice-versa
87
Biology
• Using its sharp ovipositor, the female thrusts its greenish, curved eggs either in to the midrib or a main vein
of the leaf, in to the petiole of the leaf, or some times in the stem;
• Nymphs are flat and pale yellow green in color; and
• Adults pale green, wedge shaped
Damage
It apparently introduces a toxin that impairs photosynthesis in a proportion to the amount of feeding,
and in this causes the edge of leaves to curl down wards, the leaf to become yellowish and then
redden, before drying out and shedding. Severe hopper burn (caused more readily by nymph than the
adult jassid and by older rather than older nymphs) can severely stunt young plants and reduce yield.
Management
Use insecticides such as
•
•
•
•
Dimecron 250 ULV 3 liters/ha;
Dimethoate 1.5 liter/ha;
Malathion 2.5 liter/ha; and
Spray applications (Théoden and Karate) made for other insect pests can suppress the population.
Many soil-inhabiting insets feed upon the fruit (pod) and/or fruit precursors. After soil, insets' feeding
secondary infections of fungi and other plant diseases causing organisms get entry into the stems,
roots, and pods. As a result direct feeding or predisposing to disease organisms may further reduce
pod production and subsequently to yield reduction. Among soil inhabiting insects, termites presume
primary importance in groundnut.
Termites
Termite is a social insect having four distinct castes, namely, workers, soldiers, the king, and the
queen.
Workers: The workers represent the majority of the colony population and are responsible for caring
for eggs, constructing, and maintaining tunnels, foraging for food and feeding and grooming of other
cast members. They are white and soft bodied. Soldiers: The soldiers are responsible for defending the colony. They are white, soft bodied with an
enlarged, hardened head containing two large jaws, or mandibles, which are used as a weapon against
predators.
Winged reproductive types: These types produce the offspring in the colony and swarm at
certain times of the year. Colonies can have both primary reproductive (one king and one queen), and
hundreds of secondary reproductive to assist in egg laying and colony growth.
The King: The king termite assists the queen in creating and attending to the colony during its initial
formation. He will continue to mate throughout his life to help increase the colony size.
The Queen: The queen termite creates the colony by laying eggs and tending to the colony until
enough workers and nymphs are produced to care for the colony. She can live for more than ten years
and produce hundreds of eggs each year. Colonies can each have several million termites with the
help of secondary queens who also produce eggs.
•
•
•
•
Termite attack on plants start from the roots, which are hallowed out;
Workers gradually extend their activities upwards;
Then the plant dies off until the stalks above the soil are hallowed out; and
Bore in to the stem below ground level causing wilting and eventually death of the plant.
88
Managing termites in agro-ecosystems
Preventing termites gaining access to plants
Seed dressing or placing persistent insecticidal barriers in the soil around the roots; poisoning the mounds
with organochlorine or organophsphate insecticides; and less persistent insecticides, such as
organophosphates (chlorpyrifos, iodofenphos, isofenphos), carbamates (carbosulfan, carbofuran), and
pyrethroids (permethrin, decamethrin, deltamethrin), have been used and gave good control.
Reducing termite densities in the vicinity of the crops
Cultural practices
Deep plowing or hand tillage exposes termites to desiccation and to predators, thus reducing their number
in the crops. Pre-planting tillage also destroys the tunnels built by termites and restricts their foraging
activities and associated damage to crops. Removal of the queen and/or destruction of the nest have
frequently been used by farmers as a traditional method for control of mound-building termites. Mounds
are physically destroyed, flooded, or burnt with straw to suffocate and kill the colony.
Crop rotation
May be useful in reducing the buildup of termites since intensive monoculture for long periods makes plants
more susceptible to termite attack; and However, winged adults of some termite species are capable of moving
in from other sites if preferred hosts are planted in the field used for rotation.
Intercropping
•
•
•
•
The most effective cultural practice used by small-scale farmers in Sub-Saharan Africa to manage insects
that have specific host ranges;
However, controversial results have been reported for termites;
Intercropping in forestry has been suggested as a means of retaining termite diversity in the crop in order to
prevent them from achieving pest status; and
Certain grasses are intercropped with different crops in western Africa to repel termites.
Removing residues and other debris from the field
•
•
May reduce potential termite food supplies and hence lead to a reduction in termite numbers and subsequent
attack; and
Termite infestation of 100% was observed in groundnut crops where the plant residues were rated very
high.
Mulches
May either increase or decrease the incidence of termites depending on whether they have any repellent
properties.
Use of plant extracts
•
•
•
•
•
Various parts of plants and plant extracts are known to be either toxic or repellent to pests of agriculture;
Plant extracts, such as those of neem, wild tobacco and dried chili, have been used;
Wood ash heaped around the base of the trunk of coffee bushes has been recorded as preventing termite
infestations;
Wood ash has also been reported to repel termites from date palms; and
Wood ash has also been used to protect stored yams, maize straw, tree seedlings, however, it requires
further verification.
Biological control
Many natural enemies (predators, parasites, and pathogens) attack termites in nature. The use of the
fungus Metarhizum anisopliae in bait stations is under use investigation in Australia. Ants (big sized
ones) were found good predators of termites.
89
Rendering plants less susceptible to attack by termites or enhancing plant vigor
The of good quality seed, healthy seedlings, and appropriate transplanting procedure is more likely to
produce healthy plants. Intensive cropping for long periods may reduce soil fertility and structure and
then lead to reduced crop vigor and an increase in susceptibility to termite attack. Crop rotation,
including fallow periods, improves soil fertility and structure. Weeds competing with crops for
nutrients, light, and water may lead to stress; Deficiency or excess of water may stress plants and
encourage termite attack. The use of inorganic fertilizers enhances plant vigor. Application of
nitrogen, phosphorus, and potassium in wheat, barley, and yam has been observed to reduce termite
incidence. Storage pests
Post harvest peanut handling/storage is the most difficult task farmers must take into account. It is at
this stage that most attack takes place. In all forms, the seed or pod is subject to attack by insects and
mites with subsequent damage, contamination, and deterioration from the time they are harvested
until they are utilized or consumed. In the store several lepidopteron and beetle pests attack
groundnut. Among storage insects, only few are identified. Of which only weevil, flour beetles, and
rice moth are important. Studies made for storage pest management at Werer indicated that beetles
could be managed by applying malathion 50% EC at 100 g/kg, pirimiphos-methyl 2% D at 0.5 g/kg,
baythion 1% D at 1 g/kg, fenithrithion 3% D at 0.25 g/kg and perimethrin 5% D at 1 g/kg.
Weed Management
Many annual grasses and broad leaved weed species infest sesame and groundnut in the major
growing areas, however, their importance vary from time to time, place to place and region to region.
Therefore, it is difficult to give a comprehensive list of weeds in Ethiopia where these crops grow. For
example: at Humera weeds such as Dinebra retroflaxa, locally known as "chewchewit", Digitaria
sp.?? and broadleaf weeds such as Launaea sp. or Lactuca sp. (Demayto), Chorchorus spp.
(Humeray/Amira or Mulukia), Pseudarthria hookei (Tekan), Convolvulus spp. (Hareg) and
unidentified species called "Dreaya" are very important. At Metema and partly at Dansha Cuscuta sp.
(Noug anbessa) is becoming important, while at Metema Euphorbia heterophylla and Andropogon
abyssinicus and Pennisetum polystachion are very important along the road sides and at farm edges.
In Werer Portulaca oleracea, Sorghum arundinaceae (Sudan grass), Parthenium hysterophorus
(congress weed), different species of nutsedge or nutgrasss, Flaveria trinerva (dikenekel),
Gynandropsis gynandra (spider flower) chorchorus spp., etc are important.
Generally, early-season weeds significantly reduce sesame yields. After planting, sesame is not highly
competitive with weeds. Annual weeds create a shade canopy and intercept sunlight above the crop.
Weeds have extensive root systems and extract moisture at the sacrifice of sesame seed production.
This increased competition for moisture and nutrients can result in a substantial reduction in sesame
growth and yield. Broadleaf weeds can also be competitive early in the season due to their fast
growth. The early-season height advantage of some broadleaf weeds seriously reduces crop yields.
Weeds cause significant yield and quality loss due to interference with the crop or indirectly
competing for resource. Even moderate infestations of annual weeds reduce yields of sesame by 20 to
60% under irrigated condition. The presence of weeds at harvest increases the moisture content in
seed and causes storage problems. During the first few weeks after emergence, the sesame seedlings
are very sensitive to weeds; hence, an effective weed control measure is vital during this period.
Different types of perennial and annual grasses and annual broad-leaved weeds compete the crop in
rainfed as well as irrigated areas. These weeds can be controlled by adopting cultural methods (crop
rotation and tillage practices) and chemical weed methods depending on weed species, degree of
infestation and weather pattern.
Field clearing: At Humera and Metema field clearing (Nedefa) is done at two different times that is
in October, soon after harvest or at the end of May or beginning of June just before planting. After
90
harvest, nedefa is done by manual labor or young growing weeds are killed by applying 2-4-D. This
activity is very effective as it removes weeds from farm before shading their seeds.
Tillage: Tillage is one of the best methods used to kill weeds growing in crop fields. For sesame,
tillage is practiced in 75% or more of the crop. Most growers cultivate one time and very few two
times and a portion of the hectare is hand hoed only at planting (minimum tillage). Deep plowing of
40-45cm depth controlled sedges at Werer.
Hand weeding: In sesame and groundnut only hand weeding is practiced. Mostly sesame is weeded
2-4 times in the season depending on the weed infestation and species. In some farms groundnut may
need only two-hand weeding. If the first weeding is done before fourth week then the second must be
done at the seventh week. Generally, these crops has to be weeded two to three weeks after emergence
to get good crop establishment and yield is directly related to earliness and effectiveness of weeding.
However, farmers do not always weed their crop timely and properly due to shortage of labor and
weather interruption. The weeding frequency established for irrigated conditions is to make the first
weeding at seedling stage (30-35 DAE). The second weeding is at initial flowering (50-55DAE) and
the third at 50% flowering and the fourth ones as necessary.
Herbicide use: Several herbicides have been evaluated in sesame but there are no registered
herbicides for sesame in Ethiopia. Herbicides such as Treflan, Dual, and Select have controlled weeds
when incorporated lightly at planting. Metolachlor 960 EC at the rate of 2.5 l/ha gave good and
prolonged control of grass and broad-leaved weeds and gave greater than 6 q/ha yield under research
managed conditions. Use of Treflan and Glyphosate (Roundup) help reduce troublesome weeds in
farmlands. Pre-emergence herbicide Stomp 330 E @ 1.48 ai kg/ha can be used before germination
and is very effective in controlling wide range of grasses and broad leaf weeds. On groundnut
Vernolate at the rate 3.96 kg/ha a.i., Nitralin 1.32, Metabromuron at 4.00 and Alachlor at the rate of
2.8 kg/ha a.i. were effective against grass and broadleaf weeds in groundnut.
Crop rotation: Sesame is deep-rooted crop and needs high level of fertility. Therefore, in rotation
leguminous crops should be included along with sesame as under. There is no defined cropping
system for this group of crops. However, farmers in major sesame and groundnut growing areas rotate
sesame with, sorghum/maize cotton and groundnut or soybean. This rotation scheme and the
biological effect of each species over the other should be determined. Generally, there are various
advantages in including sesame in a crop rotation system. Where sesame is rotated with a cereal, there
can be mutual benefits in weed control. Broadleaf weeds can be readily controlled in the cereal crop
using selective herbicides, such as atrazine or 2-4 D, greatly reducing the risk of broadleaf weeds in
the subsequent sesame crop. Similarly, grass weeds, which are difficult to control in the cereal crop,
can be easily controlled in a conventionally tilled sesame crop using pre-emergent herbicides such as
Treflan, Dual, and Stomp.
91
Table 2.31 Important weeds in sesame and/or groundnut
Scientific name
Sorghum arundianaceum
Echnocloa xolonum
Pennisetum polystachion
Portulaca oleraceae
Dinebra retroflexa
Digitaria abysinica
Zelya pentandra
Launea cornuta
Chorchorus trilocularis/fasicularis
Gaynandropsis gaynandra
Cyperus esculentus
Cyperus bulbosus
Ipomoea plebia (many species)
Convolvulus arvensis
Common/local name
Wild sorghum (
Barnyard grass
(
(
Status
Major
Major
Major
)
))
Purslane (
/
(
/
)
Blue coach grass (
)
)
(
)
)
Major
Major
Major
Major
Major
Major
Major
Major
Major
Major
Major
Setaria verticillata
Flaveria trinerva
Andropogon abysinicus
Wild lettuce (
Mulukhiyah (
/
Spider wisp/flower
Nut grass/sedge (
)
Sedge (
)
Bindweeds (
)
Bindweed (
)
Congress weed (
/
Love grass (
)
( (
)
( /
)
Tribulus terresteris
Puncture vine (
Tagetes minuta
African marigolds (
Cyperus rotundus
Echinochloa crusgalli
Elusine indica
Purple sedge (
)
Cockspur/barnyard grass
Wild finger millet (
)
Minor
Minor
Minor
Cynodon dactylon
Erricloa fatamensis
Boerhaavia erecta
Brachiaria spp.
Cuscuta campestris
Datura stromonium
Lolium temulentum
Euphorbia hetrophylla
Commelina bengalensis
Bermuda grass (
)
Nappier grass
(
)
Dodder (
/
)
Witches' weeds, deadly nightshade (
Darnel (
)
Mexican fire plant (
)
Dayflower/Wondering jaw (
/
Minor
Minor
Minor
Minor
Minor
Minor
Minor
Minor
Minor
Bidens pilosa
Amaranthus hybridus
Leucas martinicensis
Striga hermontica
Orobanchae cernua, minor &
ramosa (in groundnut)
Bermuda grass
Zanthium strumarium
Spanish needle/Blackjack (
/
Pigweed (
)
Bobbin weed (
)
Witchweed (
/
) 217
Broomrape (
/
)
)
)
Intermediate
Intermediate
Intermediate
Couch/Devil's grass
Cocklebur (
/
/
Intermediate
)
-
)
)
)
Minor
Minor
Minor
Minor
Minor
Minor
Minor
)
92
Intermediate
)
/
2.4. Vegetables
Tomatoes
Tomato (Lycopersicon esculuntum) is one of the most important and widely grown vegetable in Ethiopia.
Fresh, processing, and cherry type are produced in the country. Small-scale farmer produces the bulk of
fresh market tomatoes. Processing types are mainly produced in large-scale horticultural farms. It is an
important cash-generating crop to small-scale farmers and provides employment in the production and
processing industries. It is also important source of vitamin A and C as well as minerals. Currently yellow
type tomatoes that are high in beta-carotene are also becoming dietary important in the market. Farmers
are interested in tomato production more than any other vegetables for its multiple harvests potential of
year round production, which results in high profit per unit area. The fresh produces is sliced and used as
salad. It is also cooked for making local sauce. The processed products such as tomato paste, tomato
juice, tomato ketchup, and whole peel-tomato are produced for local market and export. Recently tomato
is recognized for treating various human diseases. Such diverse uses make the tomato an important
vegetable in irrigated agriculture in the country and the production is rapidly increasing in many parts of
the country.
Production belt
In Ethiopia, it is produced in altitudes between 700 and 2000, which is characterized as warm and dry day
and cooler night, are favorable for optimum growth and development of tomatoes. A temperature range
between 21 to 270C day and 10 to 20oC night is favorable for plant development, and fruit set in the
country. It grows better at a constant day and night temperature. A difference of 60C between day and
night temperatures was found sufficient for good plant growth and development. Fruit setting is poor
when the temperature is either high or low. Extreme temperatures cause flower drops and poor fruit set.
At high temperatures such as Werer above 350C day and 20 0C night temperatures from March to July,
cause a high blossom drop. The cultivars that are currently in production failed to set fruits and gave low
yield when the day and night temperatures were above 320C and 210C, respectively. Heat tolerant
genotypes could be the potential ones for such growing conditions. It must be also noted that tomato
flowers fail to set fruits as the result of poor nutrient imbalances and poor managements. Tomato can be
grown in many types of soils. However, well-drained friable sandy loam soil with pH of 6.7 is preferable
for early and high fruit yield. Tomato is widely produced under irrigation. Production in the rainy season
is also possible, but need intensive pest management. The bulk of tomato production is concentrated in
the Central Rift Valleys however; there are favorable growing pockets different parts of the country.
Plant characteristics
Tomato is a herbaceous plant. It is self pollinated, but occasionally out crossing occurs under high
temperatures of above 35 and 20 day and night, respectively, due to exertion of the stigma beyond the
anther cone of the male floral part. Apparently, there are diverse tomato species and genotypes that are
tolerant to biotic (diseases and insect pests) and a biotic stresses (heat, salinity, moisture stress) that have
potential to improve the commercial tomatoes for different growing regions and production purposes. The
tomato plants vary in growth habit as determinate, semi-determinate, and indeterminate. Determinates are
high in stature produce fruits for extended period whereas determinate ones are bush types early maturing
types. The plants also differ in fruit characteristics (size, shape, color, flesh thickness, number of locules,
blossom end shape, quality (TSS%, pH, acidity, juice viscosity, juice volume). The fruits may be globeshaped almost round, oval or flattened and pear shaped. They differ in skin and flesh cooler in that the red
ones are the most preferred in the local market. High TSS% (4.5-6.0), intensive red color of both skin and
93
flesh, low acid, resistant to cracking are some of the attributes important for processing industry; the
sugar and acid ratio makes an important contribution to the flavor of tomatoes.
Demand for fresh market types
Round, large, free from defects, good flavor and attractive red-colored fruits are demanded characteristics
for . Fruits should also be firm, healthy, evenly colored, good appearance and good keeping quality and
high vitamins content. The tomato fruits currently produced differ in size from small cherry types (20 g)
to extra large of beefsteak (180 g). The fruits can be categorized as small (l 50 g), medium (70 - 110 g),
big (100-170 g) and very big (> 170 g) sized. The two size extremes have low acceptance in the market.
Cultivars for processing should be:
•
•
•
•
•
•
firm with thick wall;
high fruit retaining capacity on the plant;
high processing quality, i.e., high TSS% (4.5-6.0), pH less than 4.5;
intensive red color of both skin and flesh;
better tolerant to diseases and physical damages; and
high yield of processed products.
Growth habits
Growth habit includes indeterminate and determinate while fruit shape is either flat, round, cylindrical or
pear shaped (figures 2.1-2.3).
Fig. 2.1. Indeterminate tomatoes (continue
growth)
Fig. 2.2. Determinate tomatoes
(Terminate in flower development)
Flattened Round Cylindrical Pear Fig. 2.3. Predominant fruit shapes
94
Released cultivars
Different tomato cultivars have been recommended for different purpose at different times to the
production systems for their high fruit yield and quality potential. However, it is important that, the
cultivars should be tested for adaptation before launching production scheme in areas where the cultivars
were not tested before.
Table 2.32.
Characteristics of the released tomato cultivars
Cultivars
Chali
Cochoro
Miya
Fetane
Bishola
Eshete
Metadel
MelkaShola
MelkaSalsa
Sirinka 1
Woyno
Growth
habit
Short
Short
Tall
Short
Short
Tall
Semi-tall
Short.
Short set
Tall set
Short set
Fruit shape
Square
Oblong
Plum
Cylinderical
Slightly cylindrical
Slightly flatten
Slightly flatten
Cylindrical
Pear
Round
Oval
Fruit size
(g)
80-85
70-76
90-97
110-120
140-150
130-140
90-100
60-70
40-50
60-65
40-50
Maturity
(days)
80-90
80-90
82-90
75-80
85-90
75-80
75-80
100-120
100-110
95-100
85-90
Yield
(q/ha)
431
463
471
454
340
394
345
430
450
382
249
Plant establishment
Tomato may be directly seeded to the production field or transplanted from seedbed. Transplanting has
the advantage of economic use of seeds, select superior seedlings, easiness for field establishment and
early harvest. Direct sowing requires high amount of seed of about 10 times more (4000 g) than
transplants (400g). However, seedlings thinned out from the direct seeded field could be used as
transplants to establish a different plot. Intensive field management is also important for successful
seedling establishment.
Nursery management
Transplants could be produced either in the field or in controlled green house or lath house in flats using
appropriate soil mixes. This a common practices for seedling bushiness’. Production under field condition
could follow different operations
Nursery sites
Close attention must be given to the selection of the nursery site for producing vigorous and healthy
seedlings:
•
•
•
•
•
Seedbeds should be sited in a location, where frequent visits/supervision can be carried out;
They should be away from obstructions affecting the availability of light and be close to source of irrigation
water;
Preference should be given to well-drained sandy loam soils;
The soil should be worked to loose and friable conditions; and
The beds should not be on field previously used to produce tomatoes or related crops such as Capsicum,
potatoes; an seedbeds should be rotated with other no-related species at least 3 years after each batch of
seedlings are produced.
95
It should also be protected from strong winds and the area be kept free from weeds and other plants which
are hosts of insect pests, virus and/or other diseases which are common in tomato production areas.
Seedbed preparation
The nursery field should be carefully tilled; roots, stones, and clods should be removed. The seedbeds
should be easy for cultivation, irrigation, and hardening-off operations. A suitable basic design for a
seedbed should be one-meter width with 5 or 10 meters length and 40 cm between beds to permit a
person to work half the seedbed from each side. Three kinds of seedbeds are commonly used in
producing tomato seedlings, depending on the soil and climatic conditions (Figures 2.4 and 2.5).
•
•
•
Flat seedbed: Prepared where the land is level with adequate drainage system;
Elevated or raised seedbed: This may be constructed to avoid excess water on seedbed. Used in rainy season or
when water logged soil condition is expected; and
Sunken seedbed: For areas, which have a prolonged dry season and help to conserve and economize water.
Fig. 2.4. Seedbed preparation
Fig. 2.5 Seedbed mulched with grass or straw
Seed sowing
The seedbed is pre-irrigated 1-2 days before seeding to facilitate the planting operation. About 250-300 g
seed with over 90%, germination potential is required for one hectare. About 15 beds (3,000
seedlings/ 10 m2 bed) of 350 m2 are required to produce sufficient number of seedlings for planting
one hectare. Seeds should be mixed with equal ratio (1:1) of carrier (sand or soil) to facilitate even
distribution of the seed. It is sown in the row at 15 cm row apart at the depth of about 0.5-1 cm, covered
with pulverized/fine soil, and lightly firmed. The whole bed is mulched with grass or straw to protect
seeds from washing away during watering and is removed after the seedlings have emerged. The beds are
watered with watering can followed by surface irrigation after the seedlings have reached about 5 cm
height. The seedlings are then thinned at 3-5 cm spacing at the first true leaf stage and proper
management (weeding, watering) practices are followed to produce healthy and vigorous seedlings. No
further shade is necessary then after to avoid the development of long and spindly seedlings, which is a
common problem in farmers field. Raising large number of seedlings helps to select vigorous, strong and
healthy transplants. It is important to examine seedlings daily.
Fertilizer
Organic manure or compost and chemical fertilizers provide nutrients for producing healthy and vigorous
seedlings. Incorporating well-decomposed manure is conducive for good seedling production. However,
the amount of fertilizer applied on seedbed depends on the fertility of the soil. Generally about 100 g
Urea is applied at thinning (at first true leaf stage) to enhance growth.
Irrigation
At initial stages, water is applied frequently with a watering can. Application could be changed to
flooding when seedlings are about 5 to 8 cm height. Caution should be taken in watering the seedbeds. It
should be watered with a fine spray with a sprinkling can or with garden hose. Water dashed on seedbed
through a hose with large holes can easily washout the seed. The seeds bed should never be allowed to
96
dry out, nor should be kept soaked but sufficient water should be applied to wet the soil. Until the plants
are well established, the soil should be kept moist, but not wet. Keeping the surface wet or over watering
is favorable for damping off diseases. Watering is preferred in the morning or late in the afternoon, but
not encouraged in strong sun.
Seedling protection
Damping off is the most common seedbed diseases in tomato. The causal agents Pythim spp,
Phytophthora spp that are soil borne fungi are common in tomato production fields.. At pre-emergence,
the disease decays germinating seed before it pushes through the soil and causes poor seedling stand even
with seeds of high germination capacity. Whereas, at post-emergence affected seedling shrivels and the
entire plant will be lost unless control measures are practiced. Excess amount of moisture, dense
seedlings, excess amount of nitrogen, carelessly handling of plants and the presence of weeds favor
damping off disease. Protective seed treatment chemicals, burning straws on seedbed and solarization of
seedbed for about one month were reported effective in reducing the incidence.
Hardening seedlings
Seedlings need to be hardened before transplanting to the field to enabling them withstands the field
conditions. This should be done by reducing the frequency of watering and allowing the soil to low
moisture status when it is ready for field planting. Withholding irrigation water for two to three days
before uprooting the seedlings from seedbed facilitates the removal of transplants. Subsequently
Field management
Land preparation
Good land preparation (ploughing, leveling, harrowing etc) is important for better seedling establishment
and field management especially for even distribution of irrigation water in the field. Early and timely
ploughing is necessary to expose the soil to solar treatments that are useful to reduce diseases and insect
pest incidence.
Planting season
Tomato can be grown throughout the year provided diseases control measures and irrigation water are
available. It has been demonstrated that rain free, clean dry worm conditions and moderately uniform
temperatures are favorably for high fruit set, clean fruits, less diseases incidence and for high quality fruit
production. However, heavy rainfall is detrimental to the plant and can result in poor fruit set and low
fruit yield and quality. The cooler month (August-November) sowings produced high yield
Spacing and population
One of the management practices that greatly influences tomato fruit yield is plant population and
spacing. The distance between rows and between plants depends on the methods and purpose of
production, soil fertility, plant structure and vine types, the farm equipment and the method of production
intended to use. Tomato cultivars are spaced 70 cm between rows and 30 cm between plants. Generally,
plant spacing of 100-120 cm between rows and a 10-30 cm between plants with either single or double
rows could be used. Plant population per hectare is estimated at 42,000 to 100,000.
97
Transplanting of seedlings
Healthy, vigorous, stocky, and succulent seedlings should be selected. Seedling will be ready for
transplanting 28-35 days after sowing or at 2-3 true leaf stages or 12-15 cm height for field transplanting.
If seedlings are too young, it results in stunted growth or if they are too tall and leggy, there will be poor
in field establishment (Figures 2.6 and 2.7). Prior to transplanting, a hole is made with pegs that are big
enough to accommodate the roots. The seedlings then be placed at about 10 cm depth as in the nursery.
Hand or foot to prevent the roots from dry out must gently firm the earth around the roots. This is
common not done in farmers’ field. Transplanting could better be done late in the afternoon or in the
morning in order to reduce the risk of poor establishment.
Fig. 2.6. Tomato seedling at first true leaf stage
Fig.2. 7. Strong seedling (left) and over matured seedling (right)
Staking and Pruning
Plant support (staking) is an important production practice for tomato production. Short set especially
processing types that are hard skinned could be produced without support, however, all fresh markets
could be produced with support or mulch to produce clean and health fruits for the fresh market Staking
has the following advantages:
•
•
•
•
•
•
•
•
•
protecting fruits from soil contact,
ease of fruit harvest,
cultivation,
chemical application,
less diseases incidence,
early yield,
clean fruit,
extended harvest, and
less fruit and plant damages by wind and other hazards.
Individual or all plants could be staked (a pole placed about every one meter) in and supported with
horizontal trellises of two to three wires at 20 cm above the ground. Small-scale farmers using different
local materials such as bamboo, eucalyptus, etc commonly use this in tomato production.
Mulching
In addition to staking and pruning practices, mulching unstaked tomato plants with grass straw could
reduce fruit losses by protecting the fruits from direct contact with the soil. It also contributes to weed
supers ion, conserve soil water and influence the root environment for better growth of the tomato plants
98
Water Requirement
Tomato plant has a high water demand for its large plant biomass and high fruit yield. The fruit contains
about 90-96% water. Insufficient water during flowering and fruit development leads to flower and fruit
drops, blossom end rot, physiological disorder and subsequently low fruit yield and quality. Therefore,
proper irrigation water management at different developmental stages (seedling, vegetative, flowering,
fruiting is the most important practices to be considered for high quality fruit production. Furrow
irrigation system is the most common practice used by farmers but is poorly managed due to lack of
experiences (Figure 2.8). Currently, around Melkassa on light soil, water is applied every 3-5 days for the
first 3 weeks after transplanting and every 7 day then after. However, drip irrigation system is becoming
important for efficient use of water and for good fruit harvest.
Fig. 2.8. Field management of tomatoes
Fertilizer
Well-decomposed farmyard manure, composts and chemical fertilizers could be used to increasing yield
and quality of both fresh and processing tomatoes. The rate and method of application is important for
efficient use of nutrients hence side dressing and foliar application (solution of macro and micronutrients)
are the important ones. Tomato plants produce stunted growth, small leaves and poor fruit yield if the
plants are not nourished at different growth stages (vegetative flowering and fruiting). In absences of
well-decomposed manure or compost, farmers could apply different levels of NP fertilizers. In light soil,
200 kg/ha DAP (18 N and 46 P) is broadcasted and 100 kg/ha urea (46% N) is side dressed at
transplanting and early flowering, respectively.
Crop protection
Diseases
Disease is one of the major constraints affecting tomato production at different plant growth stages and at
post harvest. Diseases reduce yield and causes complete loss of the crop in the field. Climatic conditions
such as temperature and moisture especially high relative humidity, less sunshine, high night temperature
increases the disease incidence. The most common ones in tomato production fields are root nematode
(Figure 2.9), septoria leaf spot (Septoria lycopersici), late blight (Phytophtra infestant) (Figure 2.10),
early blight (Alternaria solani), powdery mildew (Leveillula taurica) and viruses as well as rootknote
nematodes especially Melidogene cognita which is the dominant species in Rift Valley. Control measures
will be taken at the right stage.
99
Fig. 2.9. Root nematodes
Fig. 2.10. Late blight disease of tomatoes
Insect pest causes severe losses in tomatoes. The major insect pests are potato tuber moth, African boll
worm (Figure 2.11) and red spider mites. The tobacco white fly is an important pest in the Awash Valley
known for its ability to transmit tomato yellow leaf curl virus. Control measures must be taken
accordingly.
Weeds
Fig. 11 African Ball Worm on tomato fruits
Brume rape (Orobanche) is the common parasitic weed on tomato production in the Rift Valley region
(Figure 2.12). Cultural control practices such as deep ploughing and flooding of tomato field for two
consecutive months reduce Orobanche seed in the soil. Soil solarization of the field with clean plastic
cover for 45 days during the hottest months of the year (May) can significantly reduce orobanche spp.
seed bank in the soil. Soil fumigation with Methyl bromide (800 l/ha) under polyethylene cover for seven
days was effective for soil sterilization and reduced the incidence. In addition growing trap crops such as
maize, sorghum, onion, pepper etc. continuously for two consecutive years also reduced Orobanche seed
bank in the soil by about 60%. It is important to continuously up root the weed before it flowers and set
seeds.
Fig. 12 Orobanche in tomato field
100
Physiological disorders on fruits
A number of physiological disorders affect tomato fruit quality as shown in Figure 2.13. These occur due
to nutritional deficiencies, extreme temperatures, moisture stress, varietal characteristics etc. The most
common ones currently observed in the main production region are blossom end rot, blotchy ripening,
catfaces, cracking, puffiness, and sunscald. The plant be properly managed to reduce and avoid the
incidences.
Cracking
Sunburn
Catface(Poor pollination)
Nutrient deficencies
Fig. 2.13. Philological disorders of fruits
Harvesting
The stage of maturity at which tomato fruit depends on:
•
•
•
the purpose for which they are grown (fresh or processing);
the distance they are transported from production to retailer or consumers; and
availability of storage facilities.
The fruits could be harvested at different ripening stages with creates or plastic boxes:
Mature green: When the fruits are fully green, the seed cavity filled with jelly substance, and the
seeds are well developed Turning/breaker: When the surface of the fruit, at the blossom end, turns to pink Pink; When most of the surface of the fruit is turned to pink Red/hard ripe: When the fruit is fully colored, but firm flesh Over ripe: When the fruits are fully colored, but soft Fresh market tomatoes could better be harvested at turning stage, i.e., when fruits can be easily
transported for distant market or stored for long period. For processing, fruits must be harvested when
they are red ripe so that they can directly be sent to the processing plants. Depending on cultivars, fruits
could be ready for harvest at about 75 to 90 days after transplanting. The fruits could be carefully
removed from the plant and put on the create or plastic boxes. The duration of harvest for fresh market is
about 5-7 times (30-40 days). Harvested 3-4 to times manually or single machine harvest. Harvested
fruits will be cleaned in the machine and directly transferred to the processing plant where all are machine
operated. Since tomato, fruit is above 90% water, careful picking, packaging and transportation is
important to ensure better price.
101
Post harvest handling
The high perishable nature of tomato fruits require careful attention in the harvesting and post harvesting
operations in order to reduce losses and meet market demand and to fetch high price. The post harvest
losses is high due to moisture losses, rough handling and packaging, bruises, diseases and transportation.
Round and thin-skinned cultivars such as Marglobe, Hienz 1350, and Moneymaker are highly perishable
as compared to the pear or cylindrical and thick-skinned ones such as Melkashola, Melkasalsa, Roma VF.
Firmness of per carp tissue is a key component for long storability. Currently, plastic and wooden boxes
are used for harvesting and transporting operation. These have become important to avoid injury and
reduce, decay and softening of fruits that affect the attractiveness of fruit in the market.
Sorting and grading
Once fruits are harvested they must be sorted into marketable and unmarketable especially those of poor
quality due to physiological, pathological and mechanical damages.
It is important to select:
•
•
•
•
•
•
firm, not over ripe;
fairly well formed;
smooth, clean and well developed;
good color,, texture and flavor;
free from blemishes and defects like sunscald, injury, puffiness, cat faces; and
Good appearance
Losses are high if fruits are not properly handled and properly disposed immediately. Organized tomato
market channels is needed in order to assist and encourage those involved in the development of fresh
market tomato industry.
Packaging
In a good standard quality container, that attracts consumers. Tomatoes could be packed to a net of 6 to
10 kg tomatoes for short and distance markets. Fruits could be stored under ventilated ambient storage
and immediately. In addition, fruits could be processed in a form of small-scale homestead processed in
form of juice and ketchup for local markets.
Storage
It is important to distribute to the market before lost market quality. Fresh market tomatoes harvested at
turning stage can be held a week at 10-12 0C. long storage for 1-2 weeks. However red ripened will not
stay more than 7 days. Fruits could be stored in ventilated ambient conditions or cold storage. Harvesting
at breaker stages has the advantage of keeping fruit for longer period. Storage in breaker and turning
stages has about five days storability advantages over fully red ripen fruits.
Seed production
The field culture of tomatoes for seed is almost identical with that of fruit production. Different
management steps are followed to produce good quality seed.
Rouging and isolation
Plants should be thoroughly examined for true to type (vegetative growth and fruit characteristics).
Those affected by diseases must be removed immediately. Even if the tomato varieties are self
pollinated, it is important to isolate from one another to prevent varietal mixes and to avoid small
percentage of cross-pollination that may occur especially where pollinators such as bees are present.
This is important to avoid even the slightest contamination.
102
Harvesting, processing and drying
Depending on cultivars fruits could be harvested in 90- 120 days after transplanting. Healthy and true
to typical fruits are selected for seed extraction. The fruits must free from disease and any physical
damage and it must be typical to the variety in color, size, shape etc. The fruit should be red ripen,
under no circumstance rejected fruits be used for seed production. Since tomato seeds are embodied in
a jelly like substance, their extraction requires especial efforts. Different extraction methods are used
depending on the availability of facility or technology and the amount of seed to be extracted. The
fruit are squeezed and crushed into a container such as bucket. It is then frequently stirred at least 3
times daily to maintain uniformity of fermentation in the container and to avoid discoloration of the
seed as well as prevent fungus growth. The process of fermentation could be for two days (36-48
hours) under room temperature (24-270C). If it is cooler, the process can continue for one day i.e. for a
total of 72 hours but it has to be continuously monitored for unwanted seed germination, which
eventually affects seed quality. Generally, when cottony growth is observed on top of the container,
the fermentation is about completed. The seed is then repeatedly washed 2-3 times with tap water till
the seed is free from pulps. During the process, the seed will sink to the bottom and clean seed will be
collected after the pulp has been drained off. The seed is then spread on suitable tray or mat/nylon
net/cloth bags and dried in the sun or under shade for about two days to bring down the moisture
content between 7-9%. The seed should be put in plastic bag, so that they do not absorb moisture from
the air. The fermentation processes has been effective in controlling seed borne disease such as
bacterial canker. In addition to the above practices, fruit can also be squeezed on a container such as
tray and directly dried without fermentation. However, this practice will not help control seed bore
disease as the former practices.
Seed yield
Yield of tomato seed vary considerably with varieties, the ratio of fruit to seed yield vary from about
200-300 to 1 and even less for some. Seed yield can be between 90 and125 kg/ha. The 1000 seed
weighs is about 2.7 g. with 92-97% germination and with a germination rate of about 6-8 days.
Seed storage
Under local conditions, the dried seed can be stored in plastic or cloth bags under cooler conditions or
hanged in shade (open air) till the next planting season. Under commercial production, tomato seeds
could better be stored in sealed container. The seed can retain full viability for about 3-4 years if kept
at room temperature at low moisture content of about 9% and relative humidity up to 70 percent.
Onion
Onion (Allium cepa L) is an important bulb crop in Ethiopia. It is recently introduction and rapidly
becoming popular among producers and consumers. It is widely produced by small farmers and
commercial growers throughout the year for local use and export market. Onion is valued for its
distinct pungency and form essential ingredients for flavoring varieties of dishes, sauces, soup,
sandwiches, and snacks as onion rings. It is popular over the local shallot because of its high yield
potential per unit area, availability of desirable cultivars for various uses, ease of propagation by seed,
high domestic (bulb and seed) and export (bulb, cut flowers) markets in fresh and processed forms.
Onion contributes substantially to the national economy, apart from overcoming local demands.
Products like bulbs and cut flowers are exported to different countries of the world. The crop is about
1.75 million birr worth cut flower stems were exported. In 2001, 8.5 million birr dry bulb was
exported mainly to Djibouti market. Currently many farmers have changed their life in onion
development program. With the growing irrigated agriculture in the country, there is a great potential
for extensive onion seed and dry bulb in different production belt in the country. This note
summarizes improved dry bulb and seed production technologies.
103
Adaptation belt
Temperature is noted to be one of the most important environmental factors for onion dry bulb and
seed production in Ethiopia. The crop requires cool condition during the early part of its development
and warm condition during bulbing, bulb maturity, harvesting and curing stages. Onion bulbs have
specific temperature requirement for seed and bulb production. In the country, onion can be grown in
700-2000 meter above sea level. Temperature temperatures of 20oC - 26oC day and 11 - 15oC night
are ideal for bulb production. In cooler areas where temperature fall to 4-100C or at an altitude of
greater than 2000 masl bolting and disease resistant or tolerant varieties like Red Creole could be
used. High temperature favors bulbing and accelerates maturity then results in small, split, double and
low yield and quality bulbs. At lower temperature, there will be a delay in bulbing and maturity at
least by 2-3 week and yield will be low. However, low temperature is required for flower stalk
development, and then warm and dry conditions for seed maturity and harvest. It is important to
identify locations with optimum climatic conditions favorable to attain high yield and quality of dry
bulb and seed production. Onion can grow in all types of soils from sandy loam to heavy clay.
Highest yield will be obtained from freely drained friable loam soil with pH of 6-6.8. Due to build up
of soil borne diseases, it should be rotated with unrelated crops such as beans, cereals, and onion
could be planted every 3 or 4 year.
Plant and variety characteristics
Different types of onion cultivars are available. These are fresh market, bunching and dehydrator types,
which could be open pollinated, or hybrids. The fresh market types (red colored, highly pungent) have
high acceptance in the local market compared to bunching and dehydrator types. The dehydrator onions
are large and are commonly produced for flaxes, onion powder, and onion rings that are mainly used for
snacks. The onion cultivars vary in vegetative characteristics such as foliage length, leaf arrangement
(erect, pending) and leaf color. They also differ in bulb characteristics, internal structure (single, double,
multiple) bulb shape (Figure 2.14), color (red, yellow, white), flavor rate (sweet, mid pungent and
pungent. In addition to the above characters, cultivars also differ in storability (short, medium, long), bulb
size, dry matter content (7-20%), total soluble solid (TSS%) as well as bulb maturity. Dry bulb with high
dry matter is firmer and hence more resistant to damage. The onion genotypes also differ in ease of seed
stalk development and kinds of physiological defects like splitting, doubling, thick necks and pre mature
bolting. There is a strong local preference for red bulb color and high pungent with long shelf life.
Fig. 2.14. Dominant shapes of dry onion bulbs
The onion crop is highly cross-pollinated. The intensity varies between 30-90% depending on
availability of pollinators. The pollen usually sheds before the female part is receptive (Protoandry)
and this makes self-pollination difficult. Depending on the cultivars, the number of flower stalks
produced by a single onion dry bulb varied from 3-12 flower stalks and it produces about 250 to 1000
flower per umbel under Melkassa conditions.
104
Description of released varieties
Five cultivars are released and produced by farmers however the materials be tested for adaptability
before launching extensive production program
The cultivars
Adama Red
It is a dark red colored and firm, very pungent, flat globe shaped and susceptible to purple blotch disease.
It flowers and set seed very easily. It is accepted both by producers and by consumers and is
successfully produced by small farmers and commercial growers in most regions of the country. The
cultivars are grown in Awash Valley and Lake Region in larger quantity.
Melkam
High yielder but light red in bulb color than Adama Red. It is similar in all the remaining
characteristics to Adama Red.
Red Creole
It is red, firm, very pungent, not easily bolting, and relatively tolerant to purple blotch disease.
Bombay Red
Thick flat shaped, light red, light pungent, susceptible to purple blotch disease. It has a high
proportion of split bulbs and have short shelf life compared to Adama Red.
Dereselgn
Early maturing, medium red, large bulb sizes and fits to short growing season
Table 2.33. Characteristics of released/recommended onion cultivars
Character
Leaf color
Leaf arrangement
Bulb size(g)
Bulb shape
Bulb skin color
Bulb Flesh color
Maturity (days)
TSS%
Dry bulb q/ha
Seed set
Adama Red
Medium green
Erect
60-80
Flat globe
Dark red
Reddish white
110-130
10-13
350
High
Melkam
Dark green
Erect
70-90
High globe
Medium Red
Reddish white
110-130
10-12
400
High
Red Creole
Light green
Medium
80-100
Thick flat
Medium red
Reddish white
130-145
11-14
300
Resistant
Bombay Red
Dark green
Medium
85-100
Flat globe
Light red
Reddish white
<120
9-11
300
High
Dereselgn
Deep green
Erect
85-100
Globe
Medium red
Reddish white
90-110
10-18
300
High
*Growing altitudes (500- 2400 m with optimum ranges of 700-1800 m), Soil pH (6.5-7), Seeding rate (3-4 kg), maturity
period (110-130 days) are not very different among the cultivars. The first two cultivars are widely demonstrated and
popularized and extensively produced in many regions of the country.
Plant establishment
Onion dry bulbs are produced either by direct sowing to the field or transplanting seedlings or from
dry sets depending on the growing conditions of specific region.
•
•
Transplanting has the advantage over direct sowing on economic use of seed and for selecting superior
(healthy and vigorous) seedlings. It is easy to weed and water during the early period of onion growth. It
enables the farmer to attend closely to the seedlings in beds;
Direct sowing in the field requires high amount of seed of about three times (12 kg) more than using
transplants (3-4 kg). It requires also proper land leveling, weeding, and thinning. Seedling thinned out from
direct seeded plots can be transplanted to the field; and
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•
Unlike seedlings or seeds onion sets can adapt to short growing seasons and are tolerant to harsh
environment. Sets are small dry bulblets usually less than 2.5cms in diameter. They are earlier and produce
heavy crops than either seeds or seedlings. One has to select the planting methods appropriate to specific
growing conditions.
Nursery management
Nursery site selection
Good seedlings are essential for the success in onion bulb production. Very close attention must be
given to the selection of nursery site, seedbed preparation, and management in order to produce
vigorous and healthy plants. The seedbed should be located on areas where there is a well-drained
sandy loam soil. It should also have access for frequent visits. The seedbeds should be with other
crops as a rotation to avoid disease build up and to produce healthy and vigorous seedlings.
Seed bed preparation and seed sowing
Land will be well prepared and appropriate seedbed produced. Three kinds of seedbeds are commonly
used for raising vegetable seedlings including onion. This could be raised, sunken, or flat ones.
Raised seedbed is constructed for the rainy season sowing to drain excess water or when water logged
soil conditions are expected.
Sunken seedbed is used in areas of prolonged dry conditions to conserve moisture.
Flat seedbed is used where the land is level with adequate drainage. Seedbed of 1 x 5 or 1 x 10 meters
could be prepared About 3.0 to 4.0 kg, 90-95% germination seed is required to produce seedlings for
one hectare of land where as 12 kg seed of the same quality is needed for direct seeding. About 60-70
seedbeds with an area of 450 m2 are required to produce sufficient number of seedlings for one
hectare planting. The seeds should be sown at 10cms between rows, lightly covered with soil and
mulched with grasses or straws till seedling emerged (2 - 5cms) from the soil (Figure 2.15).
Sunken
Flat `
Raised Fig. 2.15. Cross-section of, sunken and raised seed bed
Water application
Onion is a shallow rooted crop. Uniform application of water is essential for obtaining healthy
seedlings. Watering cans could be used to avoid wasting the seeds from the runoff and improper
application of water to the seedlings at early stage of growth. Application to flooding should be
carried out when seedlings are about 5-8cms heights. It is important that the soil should be kept moist
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but not wet. Watering is preferred in the morning or late in the afternoon but not encouraged to water
during hot and sunny hours to reduce high evapotranspiration and encourage assimilation rate.
Fertilizers
Organic manure, compost or chemical fertilizers, provides nutrients for producing healthy and
vigorous seedlings. The rate and method of application is important for high and quality bulb yield.
The amount applied depends on soil fertility. The plots will be applied well decomposed manure
under poor soils 100 kg DAP is applied before seedling and 100 kg/ha urea is at 15-20 days after
sowing to enhance the growth of seedlings. The weeding and cleaning operations should be carried in
order to produce healthy and various seedlings.
Seedling protection
Unlike Tomato and hot pepper, diseases and insect pests are not very serious problems in onion
seedlings. Regular field rotation and using clean seedbed are important operations to minimize the
incidence. However, when thrips and purple blotch symptoms are observed chemical control
measures are applied. Currently, Cypermethrin (100 g. a.i/ha) in about 500 –700 liters of water and
Mancozeb (3 kg/ha) should be applied for insect pests and diseases control, respectively.
Field management
Land preparation
A planting site should be clean, free from weeds, and flat. The land must be well plowed and
harrowed to a fine tilth, leveled and it should be fairly firm and free from clods before either seeding
or transplanting seedlings. Onion must be rotated ones in 3-4 years with unrelated crop species in
order to minimize the risk of soil born diseases, insect pests, and weeds.
Planting season
Onion dry bulb can be produced throughout the year provided diseases, insect pests control measures, and
dependable irrigation water is available. However, the yield and quality of dry bulbs seem to vary from
season to season due to the diverse climatic conditions prevailing in production areas. For example at
Nazret, Adama Red produced the highest total and marketable dry bulbs during the cooler growing
periods, July, August and September sowings, with a yield of about 180-200 q/ha..
Plant spacing
Plant spacing is an important practices that influencing dry bulb yield and quality of onion. Onion is
planted in flat ridges to effect field operation (cultivation, weeding, irrigation etc) Spacing of 40 x 20
x 10cms, 40cms bed including furrow, 20cms between rows on the bed and 10cms between plants
with 333,300 plants/ha gave high yield (150 q/ha) and was easy to management of the plant. This is
suitable for small-scale hand operated production system. The spacing could be adjusted depending
on the availability of facilities especially for tractor operated large-scale production.
Transplanting seedlings
Depending on the climate soil condition and cultivar, seedlings will be ready for transplanting 45-55
days after seeding. Healthy and vigorous seedlings of 12-15cms height or 3-4 true leaf stages are
carefully uprooted from the seedbed. Prior to planting pre irrigation is also carried out to settle the soil
around the transplants and facilitate the planting operation. Following the recommended plant
spacing, holes are made with pegs that are large enough to accommodate the roots. Then seedlings are
placed in a hole and the soil is pressed around the root by hand or on foot to avoid formation of air
pocket near the root and to protect the seedlings from dry up. Water must be applied immediately
after transplanting. Similar to other transplanted vegetables, withholding irrigation water for two to
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three days before uprooting the seedlings from seedbed facilitates the uprooting and subsequent good
field establishment of seedlings. Light root pruning plant parts is practiced to facilitate the
transplanting operation.
Fertilizer and mulching
Onion production can benefit the producer from the addition of manure, compost, and/or inorganic
fertilizers. The first two are locally available and are important in supplying the necessary nutrients,
improves soil texture and water holding capacity of the soil. The amount to be applied depends on the
type and fertility status of the soil. The rate for a particular locality or soil types has to be determined
before application.
Water requirement
Onion has a shallow and fibrous root system with most roots concentrating in the top 30cms of the
soil. Uniform application of irrigation water is also needed to achieve high yield and quality dry bulb.
Furrow irrigation is the most common practice used in onion production, however, the frequency and
amount of irrigation water applied varies with cultivars, soil types, season, amount, and distribution of
rainfall and development stage of the plant. Generally, water is applied more frequently, every 4-5
days for the first 3 to 4 weeks after planting and extended to every 7 - 9 days then after. As the onion
begins to mature and the tops begin to fall that is 15-25 days before harvest, irrigation should be
terminated. It has been note that late and infrequent application of irrigation water results in thick
necked, none uniform and low storable bulbs.
Cultivation and weed management:
Three to four cultivations are needed for the control of weeds, need for fertilizer dressing, and for
reconstructing the ridges. Cultivation should be shallow to avoid root damage. Onion takes about 4555 days to develop a seedling having 3-4 true leaf stages.
Crop protection
Onion could be produced under both rainfed and irrigation if proper care is taken against disease and
insect pests.
Disease
Purple blotch and downy mildew are the two common diseases in onion; however, purple blotch
(Alternaria Porri) is a very severe disease in most onion-growing region in the country mainly during
wet season. It attacks leaves, bulb and seed stalks and subsequently reduces yield and quality. In the
initial symptom, small whitish sunken spot appears on the leaves. Later, the spot turns purple and is
surrounded by chlorite areas. At severe infestation, the whole leaves turn brown and dries. In order to
overcome the problem, using clean seed, growing under well-drained soil, rotation with non-related
crops (planting ones every 3-4 years), burning crop debris, and frequent chemical application are
good practices. The yield losses are estimated to be about 50%. Mancozeb 3.0 kg/ha or Captafol 80%
WP, 0.3% at about 500-700 liters of water/ha at 7 days interval was reported to be effective. About 57 sprays are applied per season depending on weather conditions and the intensity of the disease.
Recently, Ridomil MZ 63.5 (3.5 kg/ha) is also applied. Neck rot diseases also occur during and after
harvest. Bulbs that are well dried are less likely to be affected.
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Pest
Thrips (Thrips tabaci): It is the most common serious pest in onion production in the country during
the worm weather and causes considerable losses. It leaves on bulbs and inflorescences and affects
dry bulb yield and seed quality. Severities vary from season to season and year to year. Under
Melkasa condition, thrips population was the highest from February through April and the lowest
from June through August and an overall yield loss of 33.5 % was reported. Dipping seedlings in 1%
Diazinon solution before transplanting and spraying cypermethrin at 100 g. a.i /ha or 500 ml/ha. at 7
days interval significantly increased bulb yield. The chemicals are diluted in 500-700 liters of water.
The application has to start when about 10 thrips observed on the plants and continue till maturity.
Onion Thrips
Harvesting and curing
Onion bulb should be harvested at the right stage. It takes about 55-65 days to develop visible bulbing
from the time of transplanting and then 60-70 days bulbing to maturity. Thus, it takes between110 and
130 days from transplanting to bulb maturity. Bulbs are better harvested when leaves are dry or fall
over. However, harvesting is possible when 25-50% of the tops are down. Farmers are used to harvest
even earlier depending on availability of good market price.
Onion bulb grading
After bulbs are harvested, curing is essential to prevent disease infection and improve its storage life.
The bulbs are left for 3-5 days until leaves get completely dried and the neck gets soft. This could be
accomplished either in the field or in open shade or ventilated store. At this stage, the nutrient from
the leaves move into the bulb until the foliages are dead and the neck gets soft. Such curing practice
improves yield and quality in terms of skin color and its retention. Once cured root and leaves are
properly trimmed and graded it can be transported to markets or kept in storage. The yield of properly
cured dry bulbs at the research center ranges between 250-350 q/ha where as in the farmers’ fields
between 90-150 q/ha. The yield is composed of marketable and unmarketable dry bulbs. The
unmarketable bulbs include under sized (below 20 g), diseased, decayed, physiological disordered
such as thick necked, splits and bolted ones that are influenced by the location, seasons, cultivars and
management practices. Thick necked occurs mainly when some proportion of the bulb fail to
complete bulbing and leaves continue growing.. Heavy and continuous watering and late application
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of nitrogen contribute to thick necked. Such bulbs have short post harvest life. It could be reduced if
bulbs are harvested when all leaves are dry
Harvesting onion on the right and grading dry bulbs on the left Post harvest handling
All the necessary precautions measures have to be taken to keep the produced health and in good
conditions until reach consumers. Careful handling during harvesting, transporting, and loading is
necessary to avoid physical damages. Dry bulbs will be sorted to marketable quality that fit for normal
consumption. It is important to eliminate defected, sprouted thick necked and spitted bulbs removed
and standard quality selected and saved. The marketable bulbs will be categorized according to the
market standards .Onion dry bulbs are grade for distinct shape and color, district size grade, free from
any damage sufficiently dry and free from foreign smell. In addition, could be packed in 25 kg in
plastic netted open jute.
Dry storage
Types of cultivars, quality of bulbs, field management, and handling practices are important
conditions influencing storability. Cultivars with soft neck and high dry matter store well compared to
the thick necked and low solid content. Similarly, cultivars with high dry matter stores well. It is
important to develop less cost ventilated storage facilities applicable to small farmers. Onion could be
stored under natural ambient ventilation or forced ventilation. Under cold storage dry bulbs could be
stored either 0-5OC at 65-75 % or 25-30 OC at 65-75% RH. Simple ventilated storage constructed
from poles, wire meshes and sheets of grass roofing found effective in extending the shelf life of
onion in the rift valley. Such simple ventilated shade could be constructed from any locally available
materials such as bamboo, grasses, small poles etc and be effectively used for small and bulk storage.
Ventilated structure also minimize losses and maximize storage period which could be achieved by
orienting the store to the prevailing wind and sometimes by hanging the bunches and stacking the
bulbs on wooden/mesh shelves with sufficient air space. The bulbs could be stored 2-4 months.
Bulb store
Seed production
Temperature has a great influence on flowering of onion. A period of low temperature (9-170C is
required for flower stalk development. In Upper Awash and Lake region, the months of September to
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February with temperatures of 26-280C day and 11-160C night supplemented with low humidity
provides good conditions for flower stalk emergency and subsequent satisfactory seed set for easy
bolting varieties. Drier and low humid conditions with ample sunshine and the absence of strong wind
are suited for seed maturity, ripening, and harvest practices. Excessive rainfall and cooler conditions
during flowering leads to diseases and poor fruit set and ripening and makes the harvesting of seed
difficult. It also delays seed maturity and results poor quality seed.
Pollination
Onion is highly cross-pollinated. The intensity varies between 30-94% depending on availability of
pollinators. The pollen shed before the female part is receptive (protandry). This makes selfpollination impossible without bagging/caging the flowers. Various insects are involved to carry
pollen between flowers. The availability of suitable pollinators, such as bees, which feed upon the
nectar and transfer pollen within an umbel and between different plants, is very important. Honeybee
hives could be placed on the farm to effect seed setting in commercial production.
Method of production
Two methods of production are commonly used.
•
•
The bulb to seed method has the advantage of maintaining seed quality. It allows rouging of off color,
misshapen, splits, rotten and sprout bulbs, and many stalks are also formed per bulb; and
The seed to seed method misses the above advantages but it could be used alternately (every other year)
with the other method to speed up the production practices without affecting the varietal quality
It takes about 10-12 months and 7-8 months to produce seeds under bulb to seed and seed to seed
methods, respectively.. The bulbs will be planted in the cooler period (early September to October),
which is conducive for flower stalk development and subsequent seed set.. The bulb to seed method is
the most commonly used.
Cultural practices
Large or medium sized mother bulbs (5-6 cm), uniform, typical size and color, free from diseases,
insects and other injuries will be selected and stored for about 2 months and planted to the seed
production field. The size of the bulb determines the vigor of vegetative phase and number of
reproductive shoots, which is related to number of seed stalks and to subsequent seed yield. The
optimum mother bulb planting time could be between August and October. August, September, and
October bulb planting gives high number of flower stalks and seed yield due to worm temperatures,
low rainfall, and low disease pressure during flowering, fruit set and harvest operations. All the
cultural practices such as pest control, cultivation, as well as regular water application and proper
weeding are routine operation as bulbing onion.
Isolation
All the flowers in one umbel do not open and mature at the same time. In addition, the male and
female parts of the flowers do not mature at the time and therefore cross-pollination is very common
(30-94%). So varieties should be separated by a distance of at least 600 m - 800 m. as a barrier to
reduce the chances of seed contamination. So commercial production, it is advisable to concentrate on
one or two varieties.
Harvesting, threshing, processing and packaging
Since not all the umbel in a plant matures at the same time it is desirable to harvest the field about 3 to
4 times. The seed is ready for harvest when the first formed seed in the head begin to shatter or expose
the black seed. The heads are cut by hand using shear with part of the stem attached and left to dry on
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canvas in ventilated sheds or in the sun. Much of the seed may fall from the capsule during drying
however, the seed could be fully separated by rubbing over the canvas or by light pounding on piston
and mortar for about 10-15 min. Trashes and poorly developed seeds can be removed or cleaned by
immersing seed in clean water for about 15 minutes for one or two times. The seed is then transferred
to canvas or trays and dried in sun under shade for 3 to 5 days. This has to be done immediately to
maintain seed quality.
Seed yield
A great variation was found in seed yield among the promising open pollinated cultivar. The cultivar,
Adama Red, produced the highest seed yield of 12 q/ha. Onion seed germination varies between 90
and 95% with 1000 seed weigh of 3.5-4.0 g.
Seed storage
Onion seed deteriorates faster than any other vegetable seed. It deteriorates quicker under worm
conditions (room temperature). Great care must be taken to dry the seed to 79% moisture and protect
it from excessive heat under conventional storage. Once the seed dried, it must be sealed in a moistproof container. Under local conditions, it is bettered stored in paper under dried or ventilated
conditions for at least one year.
Hot Pepper
Capsicum is a high value crop used as vegetables and spice in Ethiopia. Pepper is a high value crop in
both domestic and export markets. It is important in the local dishes, karia, berbre and processing
industries (coloring agent) and export in the form of oleoresin (red pigment) and ground powder in
different forms. It is produced in many parts of the country and serves as cash crop for small-scale
farmers. Different pepper types such as bell (sweet) pepper which is non-pungent, chili (mitimita) and
hot pepper (berbere) which is pungent are produced in which hot pepper is dominantly produced.
The pungency is due to high capsaicin (C18H27O3N) content in the fruit. Capsicum is grown in
different agro-ecological areas in which hot pepper predominates. Small-scale farmers in various
regions especially in Southern and Western Ethiopia extensively produce it. The fruits are consumed
as fresh, dried or processes products as vegetable and as a spices. The scope of this training manual is
therefore to provide information on pepper production constraints and discuses sustainable production
techniques that help research and extension agricultural development agents and other stakeholder.
Production belts
Capsicum is grown in most part of the county. The central (Eastern and Southern Shewa), Western,
North Western (Wollega, Gojam) and the Northern part of the country are the potential capsicum
producing areas in the country. Currently most of the produce comes from capsicum is grown in most
part of the country.
Characteristics
Pepper is a self-pollinating crop; however, a considerable amount of cross-pollination mainly due to
the position of the stigma in relation to the anthers. The long-styled flower in which the stigma
extends beyond the stamens favor cross-pollination where as a high degree of self-pollination is
expected from the short-styled flowers. The stigma becomes receptive before pollen shedding, is
common in many hot popper cultivars. Considering all these conditions, the importance of controlling
cross-pollination in purity maintenance of pepper cultivars must be emphasized.
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Pepper as a plant has different characteristics such as growth habit, plant height, plant canopy, leaf
width, leaf color, leaf shape, stem shape, stem color, branching habit, growth habit, nodal and
anthocyanin. In its inflorescence, it also shows difference in maturity, number of flowers per axils,
flower position, corolla color, and male sterility. The fruits also vary in their fruit position, fruit color
at maturity and a ripening, fruit position, fruit shape, fruit length, fruit width, fruit wall thickness, fruit
shape at blossom end, number of locules, pungency, and seed color, and number of seeds per fruit.
Varieties
The Ethiopian Agricultural Research Institute has so far released a number of varieties that include 3
for fresh and dry market and 2 for fresh market (green fruit) and 2 for processing. Of all these
varieties Mareko fana and Bako local are widely grown both for fresh and dry market. The rest are
just under promotion to create demand. Listed below are varieties that are recommended for
production.
Table 2.34. Adaptation and dry pod yield performance of \hot pepper cultivars
Cultivars
Melka Awaze
Melkashote
Mareko fana
Bako local
MelkaZala
Melka dima (Paprika
king)
Melka eshete (Paprika
queen)
Area of adaptation
1000-1800
1000-1800
1200-2100
1200-1900
1200-2100
1000-2000
900-1300
900-1300
900-1300
800-1300
900-1300
800-110
Maturity
days
100-110
110-120
120-135
130-145
130-150
100-120
1000-2000
800-1100
100-120
Pod character
Light red, mild
Dark red, pungent
light red pungent
light red pungent
Light red, very mild
(processing)
Dark red very mild
(processing)
Yield
(q/ha)
25-28
25-30
15-25
20-25
17-28
15-20
15-20
Climate and soil requirements
Hot pepper is grown successfully as a rainfed crop in areas receiving an annual rainfall of 850-1200
mm. Heavy rainfall leads to poor fruit set and in association with high humidity leads to rotting of
fruits. Conversely, any dry spell, even for a few days, will result in substantial reduction of yield.
Very long spells of dry weather are unfavorable for the crop growth. Hot peppers are better adapted to
warm humid climate, while worm and dry weather enhances fruit maturity. An optimum day
temperature for hot pepper is ranging from 20 to 30°C and the night temperatures ranging from 15 to
20oC. When the temperature falls below 15°C or exceeds 32°C for extended periods, growth and yield
are reduced. High temperature associated with low relative humidity at the time of flowering increases
the transpiration, resulting in abscission of buds, flowers, and small fruit. A soil temperature of 10oC
retards plant development, whereas, 17oC causes normal development. Hot pepper can grow best in a
loam or sandy loam soil with good water-holding capacity, but can grow on many soil types, as long
as the soil is well drained. Pepper prefers a light porous and well-drained soil rich in organic matter.
In poor drained soils, plants shed their leaves and turn sickly and fruit drop takes place due to water
logging conditions. It can be grown successfully in sandy loam soil provided adequate irrigation and
maturing are carried out. An ideal soil for the crop is light loamy or sandy loam rich in lime and
organic matter. Black soils are also suitable for the crop production as long as water stagnation is
controlled. Water stagnation, even for a very short period, is injurious for the plant. So, heavy textured
soils in locations where drainage facilities are inadequate should be avoided. The crop can be grown
successfully with soil pH of 6-7.
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Pepper production
Nursery management
Improper seedling production practices influence the health and vigour of seedlings. A number of
factors affect seed germination and seedling establishment. Despite seed and soil born diseases,
improper nursery management such as use of broad seedbed, excessive seed rate per seed bed,
broadcasting seeds and flooding seedlings cause harmful effect resulting either week or infected
seedlings. An adverse effect of these practices is observed in most nursery production fields in
Ethiopia. Seedlings produced by this way are weak and easily affected by diseases and insects even
after transplanting. Thus, to produce healthy and vigour seedlings follow the steps described below.
Nursery site selection
Seedbeds site should be clean, levelled and should not be close to any types of trees because the
shadow of the trees will affect seedlings getting adequate sunlight. Additionally, the falling of leaves
and barks from the trees release chemicals that negatively affect seed germination and seedling
emergence. Equally important is seedbeds sanitation. Seedbed sites should be clean from any crop
residue and isolated from vegetable fields of the same family (example, tomato, tobacco, eggplant and
pepper). Do not select seedbeds that have been used previously with the above-mentioned crops
because infection may occur from the crop residue and the related crops.
Seedbed preparation
Vegetable seedbed should be prepared carefully:
• Prepare manageable seedbed size either 1m x 5m or 1x10m; and
• Avoid broad bed size for seedbed since it is not convenient to practice different operations such as seed
sowing, cultivating, weeding, and watering and fertilizer application.
Seed source
Peppers are relatively slow to emerge and need protection from seed and soil-borne diseases. In order
to produce any crop, first, it is advisable to use the certified seeds. However, certified seeds are mostly
not readily available in many cases. Thus, farmers’ particularly vegetable growers obtain seeds either
from local market or extract their own seeds from the previous harvest fruit that categorically rejected
and unmarketable. Both purchased seeds from the local market, traditionally extracted seeds are
unreliable, and more likely attacked by seed borne pathogens and become the cause to transmit the
disease in the nursery. In order to avoid such problems, treating the seeds with chemicals prior sowing
the seeds is advisable because it protect the seeds both from seed and from soil borne infection.
Treating vegetable seeds with Apron star can also help to control disease-causing organisms during
seed germination and seedling emergence.
Procedure for seed treatment with chemical
•
•
Determine the amount of the seed to be treated; and
Calculate the amount of Apron Star required as shown below:
Example: Suppose, the amount of seeds required for one seedbed is 20 gram of pepper. The company
recommendation of Apron star for 1 kg seed is equal to 2.5 g. Then, the amount of Apron star required to treat
20 g seed can be calculated as below:
Required amount of Apron star product= 20g x 2.5g/1000g= 0.05g.
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Next, to mix the chemical with water, it is necessary to calculate the required amount of water as
shown below:
It is recommended to mix 1 kg of any vegetable seeds is equal to 10ml water, thus the amount of
water for 20g pepper can be calculated as below:
Required amount of water= 20 x 10/1000=0.02ml.
Another option
To control soil-borne, disease is to sterilize the seedbed. Place a 5-cm thick layer of straw or any other
dry organic matter on the bed and burn it. Then add water after burning is completed. This also adds
small amounts of P and K to the soil for the seedlings.
Sowing time and seed rates
Seeds of hot pepper are sown in nursery beds two months ahead of the main rainy season so that it
could be transplanted at the on- set of kremet. Depending on the size of the field, enough seedbeds
should be prepared. To raise seedlings for one hectare 0.9-1.2 kg of seed is required. Seeds are sown
to 1-2 cm depth with 5 cm between rows. However, growers commonly use high seed rate per seed
bed to secure maximum seedlings that can be used for gap filling in case transplanted seedlings failed
to be established in the fields. Using high seed rate has the following drawbacks:
•
•
•
•
•
•
It creates overcrowding and suffocation and restrict aeration;
Crowded seedlings create competition for nutrients and sun light and can lead to stunted growth of the
seedlings due to lack of enough nutrients;
Seedlings tend to be weak with less number of leaves, and lack stem strength, thickness and poor in root
development;
Create a favorable condition for the growth and development of the pathogens;
Seedlings being crowded, the diseases can easily be transmitted from affected seedlings to the healthy ones;
and
In most cases, infected seedlings will die either while they are in the seed bed or after transplanting
and become source for diseases transmission.
Thus, using recommended seed rate per unit area of land and sowing in rows is important. After
sowing, provide shade to the seedbed until emergence take place.
Water application
Watering seedlings with correct amount of water uniformly is an important task in nursery
management. Excess amount of water and incorrect method of watering will harm seedlings.
However, a number of farmers who irrigate seedlings with furrow irrigation instead of watering can.
Under furrow irrigation, it is difficult to control the amount of water and excess water is likely to
occur. Excessively wet soil on the other hand create conducive environment for disease development
and affect seedlings root growth development.
Site selection
The field site where peppers are to be grown should be carefully selected. Sites with slight to
moderate slope are ideal for pepper cultivation, as they promote drainage and necessary to avoid
poorly drain fields. When the soil is kept too wet for long time there will be no adequate air
circulation, as a result it can cause serious injury to peppers. Thus, draining excess water out of the
field is important. Locate pepper plantings as far away from tobacco, tomato, potato, and eggplants as
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possible because of the danger of disease spread from those plants to peppers. Moreover, the site
selected should not have been cropped to the above listed crops during the previous season. Crop
rotations following those mentioned crops should also be avoided, as they are susceptible to many of
the same diseases. Soils known to be high in residual nitrogen should also be avoided to prevent
peppers from producing excessive foliage at the expense of fruit. Consider the previous crop when
deciding how much nitrogen to apply; there will probably be some residual nitrogen following a crop,
which received heavy doses of nitrogen fertilizer during the previous season.
Field preparation
Plough the land thoroughly for minimum of three times to a depth of 25 cm. First plough should be
done immediately after harvest the previous crop. This help to incorporate weeds and other stubbles in
to the soil. The second plough is done after a month following the first plough to break clods and level
the field. To ensure a smooth level field for transplanting, plough the field for the third time. Manures
and fertilizers are applied before the last ploughing and covered by the fourth ploughing. Ridges and
furrows are to be formed at recommended spacing.
Seedling transplanting and transplant care
Pepper seedlings are usually ready to be transplanted to the field when they are 53 to 60 days old or
12 to 15 cm tall (pencil size) or at five true leaf stage. Hardening the plants and prevent transplant
shock, reduce water application ten days prior to transplanting. Take care not to over hardened
seedlings since it affect plants to grow slowly in the field. To transplant seedlings, carefully pull them
from the seedbeds using shovel, rake, fork and pickaxes. Take care not to damage the root systems,
particularly the adventitious roots and cover them with wetting materials, preferably sacks to keep the
roots moist and place them in a cool area under shade until transplanted. If watering is required, wet
roots only. Transplant only healthy and disease free seedlings.
Planting time
Transplant seedlings in late afternoon or on a cloudy day minimize transplant shock. Planting holes
are prepared in rows using pegs or any materials. Place seedlings at the shoulder of the ridge, if
production is thought to be under rain fed conductions or beneath the ridge if it is under irrigation.
Place seedlings properly in to the hole to the level of the cotyledons or first true leaves without
damaging or bending the main root. The soil should be well pressed after transplanting is over and
irrigate immediately to establish good root to soil contact. Proper planting seedlings greatly increase
yields as compared to the traditional way of planting with bending the root systems. It has been
observed that traditional practices with bending the root systems affect or delay the normal growth of
the plant and reduce yield.
Spacing
Planting pepper in-row is unpopular practices among Ethiopian farmers rather they traditionally plant
pepper randomly without considering standard spacing. Transplanting pepper in row at recommended
space (60 x 40 cm. for rainfed, 80 x 30 cm. For irrigation) increase productivity and has many
advantages. It provides nutrient availability and avoids plant competition, allows root growth and
development, enhances plant growth and lateral branch production and thereby increases flowering.
Additionally, it facilitates to carry out field operation (cultivation, weeding, hoeing, fertilizer
application, better drain land and conduct crop protection activities). Conversely, if planted randomly
as it was observed in farmers field plants fail to develop the size needed to produce a good crop of
fruit and provide good foliage cover to protect fruit from sunscald and reduces yield.
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Water management
Pepper is grown principally under rain fed conditions, but there is a potential to grow under irrigation
conditions as well. Pepper plants are shallow-rooted and have low tolerance to drought or flooding.
When peppers are grown under rain fed conditions, heavy rains cause flooding, pepper plants cannot
tolerate excess water, and plants will generally wilt and die if they stand in water for more than 48
hours. Phytophthora blight and bacterial wilt can occur where soil remains wet for long periods and
may cause total crop loss. Thus, fields should be drained quickly after heavy rain by constructing
ditches around the field.
When pepper is grown under irrigation conditions, long dry periods may cause plants to shed flowers
and small fruits. Although the depth of water irrigation and the volume to be applied is not yet
established, irrigation at an interval of about 8-10 days under Melkassa conditions provided good
yield. Fields should be irrigated if there are signs of wilting at midday, when stressed plants are likely
to make a slow recovery after drought injury. Irrigation should be done to maintain uniform soil
moisture to promote uniform growth and fruit setting. Furrow irrigation is recommended to be applied
early in the day so that the field is dry before nightfall. Irrigating late in the afternoon and over
irrigation promote root rotting diseases. In order to irrigate pepper field, the field should be divided in
every 5 to 6 m in to blocks and ditches should be constructed around each block to drain excess water
from the field.
Management after planting
Cultivation
Peppers have shallow roots, thus, attacked by weeds easily. Weeding around the plants is to be done
according to necessity. Hand hoeing and cultivation is needed to control weeds. Research indicated
that cultivation of pepper fields 2-3 times during plant growth period is highly advantageous because
it has been found to be effective to allow aeration in the root zoon of the plant and enhances plant
growth.
Fertilizer application
It is known that soil nutrition is depleted unless supplemented with different form of fertilizers.
Addition of cattle manure / compost just after harvest during the first plough helps to increase soil
organic matter content and maintain soil fertility. If manure is not available application of
diammonium phosphate (DAP) and urea is recommended. DAP at the rate of 200 kg/ha is
recommended to be applied after the field has been leveled and should be mixed with the soil.
According research recommendation, application of 100 kg urea per hector provides good results and
it may be applied in two split application with the receipt of little rain showers as side-dressing. The
first half can be applied in the early stage of the plant at 15 – 20 days after transplanting and the
second half can be applied at the latter stage when the second cultivation is made. Ideally, you should
conduct your own fertilizer trials to determine the optimum fertilizer rate for your area. However, the
actual amount of fertilizer to apply depends on soil fertility, fertilizer recovery rate, soil organic
matter, soil mineralization of N, and leaching of N fertilizer. Application of fertilizer according to the
level of soil fertility is necessary.
Disease Management
Several diseases can affect pepper. Occasionally, a particular disease may become significant. Listed
below are the major diseases that most frequently occur on pepper. Symptoms are described briefly.
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Colored pictures of disease symptoms are presented to help identification. Diseases of minor
importance are also included but pictures may not present. Available control options are also
suggested, though pesticide application is widely recommended. Recommended control options for
each disease are based on consideration of many types of information (scientific, experiential, and
extension bulletins) available in the Internet, because available control options developed in the
country are limited. As far as the pathogens are similar, we believe that the control option suggested
elsewhere will undoubtedly work effectively in pepper production where the problem is much more
severing. To manage pepper diseases and insect pests use resistance or tolerance varieties where
possible. Practicing sanitation to reduce inoculums and cultural practices is also important. If the
situation is worth, spraying fungicides at the last resort with correct identification of the diseases and
insect pests is advisable. Diagnosing by reading a description of the problem, especially diseases, is
difficult. However, with practice and the information provided in this manual, the development agents
can make an educated guess. In summary, the information provided in this manual is therefore,
intended to help development agents and extension personnel how to identify, monitor pepper disease
and serve to make sound decision in launching control measure against pepper diseases.
Common diseases
Seedling diseases
Damping-off is caused by Pythium spp. , Phytophthora spp. and Fusarium spp, Rhizoctonia solani,
and other fungi. Pre-emergence damping-off or seedling death may occur as a result of infected seeds
or soil borne fungal pathogens which live in the soil. The disease can occur either before or after
emergence of seedlings. Usually occurs in patches in nursery beds or in scattered areas of the field
with direct seeded crops. Seedling plants will exhibit a necrotic collapse of the hypocotyl and root
system when infected. Irregular areas of seedlings may be affected in the transplant bed or subsequent
contamination by run-off water or soil.
Symptoms
•
•
•
•
The first symptom of damping off is failure of seedlings to emerge. The seed may rot or the seedling may
have a dead or damaged radicle (primary or seedling root);
Once emerged, young seedlings may wilt when soil moisture should be adequate or the stem may collapse.
You may notice a lesion at the soil line; and
Seedlings may be stunted or not be vigorous. Young roots may be brown, black, or few in number.
Conditions for disease development
•
•
•
The disease is favored by high soil moisture and cool temperatures;
The disease occurs in infested soil. Often associated with over watering and poor drainage; and
Pepper seedlings are particularly susceptible to damping-off.
Management
Cultural Controls: •
•
•
•
•
Nursery beds must have good drainage and ventilation;
Establish seedlings in sterilized soil by burning dried wood or collected residue on nursery beds before
sowing;
Apply enough water to keep the plants growing normally, and ventilate the growing space during the day;
Avoid seed sowing on seed bed with residual, non decomposed plant debris; and
Once plants are beyond the seedling stage, they are no longer susceptible to damping-off.
Chemical treatment •
•
Coat the seed with a suitable fungicide such as Apron star or thiram. If disease appears, apply a fungicidal
drench to prevent further infection; and
In the transplant bed, avoid planting in low, poorly drained areas or into land previously in peppers.
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Powdery mildew (Leveillula taurica)
•
•
•
•
Detecting powdery mildew on pepper can be difficult. The white powdery growth characteristic of
powdery mildew diseases occurs only on the underside of leaves and it will turn brown rather than
remaining white. Diffuse yellow spotting often develops on the upper surface. Affected leaves tend to drop
off the plant, as occurs with bacterial leaf spot;
Leaf symptoms consist of chloraotic blotches or spots, with scattered areas of necrosis;
On the underside a white powdery growth may be visible; and
Heavily infected leaves abscise which can result in defoliation.
Condition for disease development
Disease may develop during warm or hot weather and during dry or rainy periods.
Management
•
•
•
Chemical control may be required during periods of sever disease pressure;
Cultivars differ in disease susceptibility; and
PBC-600 is relatively tolerant to the disease.
Bacterial Spot (Xanthomonas axonopodis pv. Vesicatoria)
•
•
•
•
Affects leaves, fruit, and stems;
Symptoms begin on leaves as small, water-soaked spots and turn dark brown and appear greasy;
Heavily infected leaves turn yellow and drop resulting in sever defoliation; and
Scabby lesions may appear on the fruit. During periods of high rainfall or humidity, spots on leaves may
coalesce causing "blight" symptoms and abscission.
Conditions for disease development
ƒ
ƒ
ƒ
ƒ
This bacterium survives in crop debris in the soil and on seed;
The bacterium is a seed-borne disease and can spread rapidly in the transplant bed and can survive in crop
debris from infected plants;
Many strains attack both tomato and pepper; and
Long periods of high relative humidity and free moisture on leaves and high temperatures.
.
Management
•
•
•
•
•
•
use pathogen-free seed and disease-free transplants. Transplant production should be carefully monitored
for disease occurrence;
avoid infected plants for field planting and do not work transplants when they are wet;
disease free seed should always be used for planting.;
Maintain soil fertility and properly irrigate the plants;
Maintain a preventative bactericide schedule in the transplant bed. Make applications on a 7- to 10-day
schedule if spots appear, and one day before pulling plants;
In the field start spray schedule when the disease first appears:
o
o
o
o
o
o
•
•
Spray copper compounds such as Koside 2000 at the rate of 25 g in 15 liter of water.
Copper fungicides may help to reduce secondary spread, but their effectiveness is limited by rainfall and dew
formation.
Adjust spray schedules according to the weather and presence of disease:
Spray one week after plants are set;
spray every 5 to 7 days during rainy periods;
spray on 10-day intervals during drier weather;
spray before rain is forecast but allow time for spray to dry;
Practice crop rotation. Use at least 1-2 years rotation between tomato or pepper crops with non host crops;
and
Crop debris should be destroyed as soon as possible to remove this source of disease for other plantings and
to initiate decomposition
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Cercospora leafspot (Frogeye Spot) (Cercospora capsici)
ƒ
ƒ
ƒ
ƒ
ƒ
leaf lesions are circular and about 1 cm in diameter with brown borders and light gray centers (frog eye);
lesions on stems, petioles, and fruit peduncles are elliptical with dark borders and gray centers;
multiple leaf lesions can cause leaf abscission without leaf yellowing.;
the fruit are not infected; and
Lesions are roughly circular leaf spots with white centers and narrow dark borders. Leaf lesions may often
appear zonate. Heavy infection may cause abscission of leaves and subsequently reduce yield.
Conditions for disease development
•
•
the fungus survives on seed and in infected crop debris.
extended rainy periods, long periods of leaf wetness, and close plant spacing enhance disease development.
Management
Fungicidal sprays can control the disease, but they are not necessary in many production areas except
during highly conducive periods
Phytophthora blight (Phytophthora capsici)
•
•
•
•
•
•
Phytophthora blight affects both seedlings and mature plants;
Plants may be attacked at any stage of growth; all parts of the plant are susceptible;
Collar rot and wilt with a blackened stem is the most common symptom;
The blight phase in which leaf spots, stem lesions, and fruit rot occur is associated with heavy
rainfall periods or overhead watering;
Affected plants wilt and branches die. Roots frequently are rotted. Under severe disease pressure,
where soil is wet, entire plants can die rapidly. Large rot areas can develop to affect at least half a
fruit; when conditions are wet, a whitish gray mold can appear on affected areas of fruit; and
This disease causes a seedling death as well as a root rot, stem canker, leaf blight, and fruit rot in
older plants. Infected seedlings show damping-off. Stem infection at the soil line is common.
Water-soaked, dark brown lesions on the lower stems (collar rot phase) usually extend upward for
an inch or more above the soil line and may expand to girdle the stems, preventing upward
movement of water and nutrients. Affected plants exhibit sudden wilting and death. The initial
canker is dark green and water-soaked but turns brown as the plant dies. Infected leaves develop
circular or irregular, dark green, water-soaked lesions, which dry and appear light tan. A mass of
white fungal growth may develop inside the fruit, and seeds usually turn dark brown or black. A
fine, grayish-white to tan mold may also become evident over the lesion on the fruit surface.
Under humid conditions, fungal growth develops extensively over the entire fruit. Fruit lesions
may also appear as enlarging, water soaked areas, which then shrivel and darken.
Conditions for disease development
ƒ Warm to hot weather with wet soil conditions; worse in poorly drained areas of the field; and ƒ Extensive rainfall is favorable conditions for development of the blight phase. Management
•
•
•
•
•
•
Avoid wet fields for pepper planting. Pump down fields rapidly after heavy rains;
Planting on elevated beds to provide a well drained root zone;
Good field drainage to remove surface water;
Good water management;
Use of fungicides (metalaxyl and copper); and
Practice crop rotation, crop rotation may be important in reducing primary inoculum. Many diseases build
up in the soil when the same crop is grown in the same field year after year. Rotation can help break this
cycle and stop the buildup of disease organisms in the field. To be effective, rotations must be carefully
planned. The present crop and all related plants or alternate hosts for the disease must be kept out of the
field. Only those crops not susceptible to the disease should be grown there. Different plant diseases will
persist in the soil for different lengths of time, so the length of the rotation will vary with the disease being
managed.
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Anthracnose (Colletotrichum acutatum, C. gloeosporiodes,
Colletotrichum spp)
Anthracnose or ripe rot is an increasingly important disease of pepper. Damage appears primarily on
fruit. Fruit may be infected by spores of the fungus at any time of development, by symptoms usually
expressed on mature fruit. Symptoms first appear as small, water-soaked lesions on fruit. These can
rapidly develop into larger sunken areas. A dark growth of the fungus may be visible in these lesions,
with tan to pink concentric circles of spores evident in some cases. Occasionally, leaf spots and stem
dieback may occur.
Management
•
•
•
Use pathogen-free seed;
Avoid injury to fruit; and
Crop rotation may be important in reducing primary inoculum.
Bacterial soft rot (Erwinia carotovora pv. carotovora)
This disease is characterized by soft, often "mushy" rot of the pepper fruit that occurs primarily after
harvest and during shipment. The rot often occurs on the stem of the fruit, and advances from that
point into the stem end of the fruit. This decay can progress quickly in transit. Field symptoms are
obvious as fruit soften and sag from the pedicel like a balloon filled with water. Softened areas
usually are gray in color. The invasion by numerous organisms will confer a characteristically foul
odor to infected fruit.
Management
In the field, maintain adequate insect and disease control. Insects can move the soft rot bacteria fruit
to fruit during feeding. Severe outbreaks of foliar diseases can expose fruit to sunscald injury and to
subsequent soft rot. Avoid harvesting while plants are wet. Do not let harvested fruit set in the sun.
Avoid fruit bruising and wounding.
Sclerotinia stem rot (Sclerotinia sclerotiorium)
This disease can be damaging some years, especially in cool, damp winters in fields near or following
susceptible crops. The causal fungus infects the stem at the soil line, individual petioles of leaves, and
occasionally fruit close to the soil surface. Stem infections frequently girdle the stem causing plant
wilt and death. When weather is moist, the white mycelium will often grow up the stem surface
several inches above ground.
Petiole or bud infections proceed rapidly downward in the plant. Entire branches may be girdled in
this manner. Fruit infected directly from the soil surface or downward through the pedicel, rot quickly
into a watery mass. The fungus survives as sclerotia formed in stems and lesions associated with
diseased fruit. These sclerotia are black, irregular in size (1/8"-3/4"), and highly resistant to
environmental conditions when in plant debris or soil.
Management
Avoid rotations involving susceptible crops such as cabbage, celery, lettuce, potatoes or tomatoes.
Deep plow fields with a previous history of this fungus to bury fallen sclerotia.
Southern blight (Sclerotium rolfsii)
•
•
•
The fungus attacks the stem of the pepper plant at the soil line and causes a soft decay of the outer tissues;
This girdling of the stem causes a wilting and yellowing of the leave s and an eventual drying of the stem
and branches; and
It seems to be most active in poorly drained, light, and sandy soils.
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Viruses (Pepper mottle, Potato Y, Tobacco mosaic, Tomato spotted
wilt)
It is difficult to distinguish single or multiple virus infections in the field. Most of these viruses induce
degrees of mosaic, mottle, vein banding, and plant stunting. Malformation, leaf cupping, and fruit
distortion may also be encountered. Accurate diagnosis is dependent on laboratory tests involving
serology or viral inclusion examination. Symptoms vary depending on the virus or strain, the plant,
time of year and environmental conditions. The range of symptoms may include leaf mottling,
puckering or curling; stem and petiole streaking; rough, deformed, or spotted fruit; stunted plants; and
leaf, blossom, and fruit drop.
Distribution mechanisms
•
•
•
•
Tobacco mosaic virus is commonly mechanically transmitted during transplant production,
harvesting, and setting;
Pepper mottle, potato Y, and tobacco etch are primarily transmitted by aphids during feeding;
Tomato spotted wilt virus (TSWV) is transmitted by thrips; and
These viruses are known to survive in numerous weed hosts such as ground cherries (Physalis
spp.), nightshades (Solanum spp.) common groundsel (Senecio sp.), wild tobacco (Nicotiana sp.),
toadflax (Linaria sp.), sicklepod (Cassia sp.), and jimson weed (Datura sp.).
Tobacco Mosaic Virus
•
•
•
•
•
•
•
•
Use resistant varieties;
Workers handling pepper plants should wash hands with strong soap and water or 70% alcohol before
handling plants. This is most important for workers who use tobacco. This will assist in controlling tobacco
mosaic virus;
Reduce insect transmission of viruses by eradicate wild host plants in fence rows and on ditch banks during
seasons when crops are not growing;
Destroy old infected crops well before planting subsequent crops;
Plant barrier crops around pepper fields. A 50-cm strip of a non-susceptible crop (maize) tends to trap
insects flying in until they become non-infective;
Spray barrier crop with suitable insecticide at least weekly to reduce population of insect vectors;
Locate fields as far away as possible from very susceptible crops such as tomato and tobacco; and
Use resistant varieties if available.
Harvesting, Drying and Storing
Pepper may be harvested at either stage, depending on the preferences of local consumers. For fresh
use, peppers are harvested at the green stage. After harvest, fruits should be stored in a cool, shaded,
dry place until they are sold. For dry or powder use, the fruits have to be harvested at leathery stage
when it contains low moisture content. The fruits to ripen take approximately 50-55 days after
flowering depending on temperature, soil fertility, and variety. However, warmer temperatures will
hasten ripening, and cooler temperatures will delay it. Harvest can be obtained from plants on a
weekly basis as fruits ripen. Pepper is commonly dried after harvest and sold as dried fruits or ground
into powder. For dry pepper, the most important consideration is to preserve the red color of the
mature fruits. The most widely adopted drying is generally in the sun. Spread the crop in thin layer on
wooden beds that allow ventilation, hard dry surface (cemented floor), and sheets made from jutes, or
black plastic sheets. It should be regularly stirred to ensure uniform drying and to reduce discoloration
and fungal growth. Correctly, dried peppers should be bagged in jute bags and should be stored under
cool storage.
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2.5. Fruits Fruit Nursery Management and Field
Production Practices
Introduction
Fruit crops consist of perennial woody trees, shrubs, vines, and palms. Based on their temperature
requirements fruits are generally grouped into three categories as temperate, subtropical, and tropical
fruits. Temperate fruits require extended chilling period for proper vegetative growth and flowering,
and are usually grown in areas with prolonged cold weather for flowering and worm conditions for
fruit set.. However, it is possible to grow them in tropics at higher altitudes. Some of the temperate
fruits can also be grown at lower altitudes by substituting chilling requirement with defoliation,
chemical application, and dry weather. Apple, pear, peach, cherry, almond, walnut, and strawberries
are grouped as temperate fruits. On the other hand, subtropical fruits such as oranges, lemons, and
grapevine grow in areas where occasional light freeze occurs. A period (a month or two) of dormancy
induced by cool weather is generally essential for their proper flowering and better fruit quality. The
third category is tropical fruits that grow in areas with free of frost problem, which affects the normal
growth and development of the crop? Dormant periods, dictated by dry weather, are essential for
many of tropical fruits such as grapefruit, lime, mango, and avocado, while others like pineapple,
banana, and papaya prefer rainfall, which is well distributed throughout the year.
Fruit crops play an important role in the national food security. They are generally delicious and
highly nutritious (mainly of vitamins and minerals) that can balance cereal-based diets. Fruits such as
banana and avocado are also rich sources of carbohydrate and fat respectively. Fruits supply raw
materials for local industries and sources of earn foreign currency by exporting fresh and/or processed
products. Moreover, the development of fruit industry will create employment opportunities,
particularly for farming communities. In general, the country has great potential and encouraging
policy to expand fruit production for fresh market and processing both for domestic and export
markets. Such development of the fruit industry will play an important role in the national economy of
the country. Besides, fruit crops are friendly to nature, sustain the environment, provide shade, and
can easily be incorporated in any agro-forestry program.
Challenges
Despite the encouraging agricultural development-led industrialization (ADLI) policy of the
government and the great potential of the country, fruit production, and consumption is generally low
compared to other developing countries. The yield and quality of fruits produced in the country is also
very low. Currently, though there are some commercial fruit farms in the country, the bulk of the
fruits are produced by the gardeners and small-scale producers. Since fruit production requires
intensive care and considerable labor, the industry is yet bound to remain mainly in the small-scale
producers. Thus, the fruit industry of the country needs much assistance particularly from research
and extension services, for its development.
Most of the fruit crops are recently introduced to the country and are new to the Ethiopian agricultural
system. As a result, nearly all the fruit materials in the hands of farmers throughout the country are of
unknown origin and poor in yield and quality. In addition to this, shortage of certified planting
materials for major crops is one of the major limiting factors in the production of fruit crops in the
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country. Furthermore, nursery and field management practices, diseases and insect management,
postharvest handling and utilization aspects of major fruits are not well studied under Ethiopian
conditions. For proper and sustainable development of the fruit industry, research on different aspects
of fruit crops to develop technologies for various agro-ecologies and different purposes is highly
imperative strong effort needs to be done to promote fruit technologies in order to improve fruit
production and productivity thereby contributes to alleviate food shortage and nutritional imbalance in
the country. This presentation focuses on nursery managements and field production practices of
representative fruit crop, Mango.
Nursery Management
Propagation
Fruit crops are propagated sexually by seed and/or asexually by vegetative materials.
Seed
Seeds develop when an ovule is fertilized by a pollen grain. The ovary becomes a fruit and the
fertilized ovule becomes seed. Under natural conditions, the daughter plants produced from a seed is
never an exact replica of the parent plants. Papaya, guava, and rootstock materials of woody fruits
such as citrus, mango, and avocado are propagated by seed. Rootstock propagation by means of seed
has the great advantage over vegetative propagation that it entails rather less work. However, the main
disadvantages of seedlings are their propensity for variation and the impossibility of predicting the
limits of this variability.
Vegetative material
Vegetative materials for propagation may come from any portion of the plant except the seed (stem
cuttings, roots, leaves and corms). Vegetative propagation produces plants with the same
characteristics as the parent plants. Some of the fruit crops produce vegetative materials naturally, e.g.
banana (sucker), strawberry, and pineapple (slip and crown). However, man also uses vegetative
propagation to produce plants, which are similar to their parents by grafting, cutting, layering etc.
However, Budding and grafting are the most commonly used practices for the major fruit crops.
Scion variety selection
Scion variety is selected based on market demanded, productivity, maturity period, shelf life,
adaptability, vigority, availability, and compatibility with the selected rootstock. Scion graft-wood
should be with a bud ready to shoot, 15 to 20 cm length in the field, pencil size thickness, and taken
from pest and disease-free and mature plants.
Rootstock selection
The rootstock is grown from seed or cuttings selected mainly for its vigorous root system, and could
be well adapted to soil and the environment where the grafted tree will be planted. It could be tolerant
to different stresses such as drought; water logged soil, some diseases and insects, alkalinity, toxicity
etc. Some rootstocks have desirable effect on scions like regular bearing, improving fruit quality and
regulating canopy size.
Rootstock seed extraction
Rootstocks fruits must be harvested when they get fully mature on the tree. The seeds are then
extracted right after fruit harvest. Mucilaginous seeds should be soaked in water for about a day and
washed to remove the flesh. Washed seeds need to dry under shade for sometime, and remove the
seed coat carefully (if only necessary) and plant the seeds preferably immediately after drying.
Raising rootstock seedlings
Rootstock seedlings can be raised either on seedbed (1m x 5m size) or in polybags (with drainage
holes at the bottom) filled with different growth media mix (usually of sand, forest soil, and manure).
124
Seeds should be planted at appropriate depth and position. Seed germination may take up to one
month depending on the temperature (the higher the temperature the faster the germination will be),
type of fruit crop and the variety. Seedbed should be under partial shade and seedlings are
transplanted when they reach appropriate size. Seedlings can be ready for grafting about 6 months
after planting on the nursery bed or polybags.
Grafting
It is one of the many methods of asexual propagation where two parts (varieties) are joined to make
one plant. The main advantages of grafting include shorten juvenility/ early fruit bearing, increase
qualities of scion and rootstock (diseases, soil pH, etc), manageable tree size, and true-to-type. For
instance, a cultivar may give high yield of excellent fruits, but may be susceptible to soil born
diseases. Another cultivar, on the other hand, may be resistant or tolerant to the soil borne diseases,
but a poor yielder. Thus, combining of the desirable characteristics of the two cultivars in one tree
using grafting gives a tree that is resistant or tolerant to the soil born diseases and at the same time
gives high yield of quality fruits. On the other hand, the major limitations of grafting are
incompatibility of scions and rootstocks needs skill and special tools, danger of disease introduction
or transmission, susceptible to physical damage (wind, animals etc) especially at early stage, and
needs wider areas for establishment of foundation blocks.
Mostly the rootstock and the scion come from two trees of the same species, but of different cultivars.
Occasionally, trees of different species, but of the same family, can be grafted successfully. In most
cases, grafting is done in the nursery. During grafting cares on proper selection and preparation of
scion, matching scion thickness with the stock, and scion budstick maturity are needed. Methods of
grafting can be classified under four categories depending on the type of grafting material used and its
position on stock plant.
•
•
•
•
Cleft /wedge/ grafting , for example mango, avocado, apple, and macadamia;
Whip/ tongue grafting;
Bud grafting (budding = grafting with a single eye or bud) (e.g. citrus, guava); and
Approach grafting
Top working
It is a type of grafting technique used to convert old and/or inferior seedling trees by a desired
superior cultivar with improved characteristics. When top working the branches are removed almost
entirely and the cut ends set with scions of the desired variety. The methods of grafting used in top
working are very numerous; however, the main ones are cleft graftings.
Essential grafting tools
•
•
•
•
•
•
•
•
•
•
•
Grafting knives
Secateurs
Grafting tape
Pruning saw
Wax
Sharpening stone
Sterilizing agent
Nails
Hammer
Labels/tags
Stakes
125
•
Figure 1: Mango grafting tools (sharpening stone, grafting knife, secateurs, alcohol, grafting tape, plastic hat)
Nursery pest management
At this stage, diseases, insect pests, and weeds must be strictly controlled. The most commonly
observed diseases at this stage are anthracnose (e.g. mango) and phytophthora/ damping-off (e.g.
papaya) while aphids on mango and orange dogs and leaf minor insects on citrus can cause serious
damage. They must be controlled by pesticide sprays, and mechanical collection and killing (e.g.
orange dog).
Irrigation
Seedlings in the nursery, before and after grafting, should be frequently watered (at least every 2-3
days interval) depending on the age, the type of fruit crop, and the temperature (the higher the
temperature the higher the evapotranspiration and the higher the frequency of watering).
Field Production Practices: mango as a model crop
Mango is cultivated in all tropical and subtropical areas. Its fruits can be eaten as dessert or used for
making various products (juice, jam, etc). It is rich in vitamin A and has fair amounts of vitamins B
and C. It is grown in Asosa, Gambella, around Harar and Babile, Deddesa Valley, Upper Awash,
Shewa Robit, Arbaminch etc.
Environmental requirements
Altitude: Mango grows best from sea level to 1400m. However, it can grow well up to 1700 m.
Temperature and humidity: High temperature and low humidity is ideal for mango production. It
can be produced either under rainfed or under irrigated conditions. Long dry season (at least two
months) is essential for its flower initiation. However, excess humidity, rain, or frost may cause
flower drop and promote mildew and anthracnose incidences.
Wind: Strong wind impedes mango pollination and hence affects fruiting. Thus, windbreak must be
used whenever necessary.
Soil: Mango tree needs deep and well drained, and slightly acidic soil with moderate water holding
capacity and light slope for drainage.
Cultivars
There are more than one thousand mango cultivars in the world. The majorities of these cultivars are
originated as chance seedlings arising from natural crossing and are maintained true to type by
asexual propagation. Except in research centers and few state farms, no known mango cultivars are
produced and most mango trees in Ethiopia are seedlings (not grafted). Seedling mango trees are
vigorous, tolerant to some diseases and produce high fruit yield. However, their fruits are not uniform
in size, shape and taste; trees have long juvenile period; unmanageable tree size for routine cultural
practices; and fruits do not mature at the same time affecting marketing.
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Almost all commercial mango cultivars are monoembryonic. However, some polyembryonic cultivars
are inferior in quality. Monoembyonic cultivars do not come true to type from seed and hence asexual
propagation is essential to get uniform materials except Apple mango. On the other hand,
polyembryonic cultivars produce both zygotic and nuclear embryos. Nuclear embryos are generally
vigorous and suppress zygotic embryo, are identical to mother plant, and good for production of
genetically uniform clonal rootstocks.
Table 2.35: Adaptation and fruit yield performance of mango cultivars
Cultivars
Apple mango
Kent
Keitt
Tommy Atkins
Sodere-11
Area of adaptation
Altitude (m)
Rainfall (mm)
< 1500
RF+Irr., Irrigation
< 1500
< 1500
< 1500
< 1500
RF+Irr., Irrigation
RF+Irr., Irrigation
RF+Irr., Irrigation
RF+Irr., Irrigation
Production status
Under popularization
Under adaptation testing
Under adaptation testing
Under adaptation testing
Recommended
Nursery
Rootstock selection: mango cultivars selected for rootstock purpose should have uniform growth, high
vigor, tolerance/resistant to soil born diseases, and favorable effect on scion varieties (regular bearing,
fruit size and quality).
Rootstock seed extraction: mango seeds have low germination capacity and fruits must be harvested
when they get ripe on the tree. Seeds need to be extracted right after fruit harvest. Then, soak the
seeds for 24 hours and wash them to remove the flesh, and dry the seeds under shade for sometime.
Remove the seed coat carefully and plant the seeds preferably immediately after drying.
Raising rootstock seedlings: Mango rootstock seedlings can be raised either on seedbed (1m x 5m
size, and at a spacing of 15cm and 30cm between the seeds and rows respectively) or in polybags
(with drainage holes at the bottom) filled with different growth media mix (mostly of sand, forest soil
and manure). Seeds should be planted at a depth of 5-7cm by positioning the convex side up. When
concave side is planted up, germination delays and the seedling becomes twisted. Seed germination
may take 2-3 weeks depending on the temperature (the higher the temperature the faster the
germination will be). Seedbed should be under partial shade and seedlings are transplanted when they
reach a height of 10cm (or at the age of 2-3 weeks). At this stage, diseases, insect pests, and weeds
must be strictly controlled. Seedlings can be ready for grafting about 6 months after planting on the
nursery bed or polybags.
Figure 2: Seed coat removal (left ) and raised rootstock seedlings (right)
Irrigation: Mango seedlings, before and after grafting, need to be watered at least every 2‐3 days depending on the temperature of the area. 127
Grafting: The average grafting success in mango is about 80% using Veneer grafting technique.
Mango can also successfully be grafted using Side grafting method. In side grafting, the vertical flap
of the rootstock bark is completely removed and one side of the scion is sliced away in a slopping
manner. While in veneer grafting, the flap is retained and tied over the scion; and the scion is sliced
on both sides of the lower portion in the form of wedge. These grafting techniques are easier, more
economical, give a higher degree of success, and ideal for top working. During grafting, the following
cares are needed. Proper selection and preparation of scion; matching scion thickness with the stock;
take terminal, non-flowered shoots of 3-4 months maturity; and defoliate selected scions on the
mother plant about 7-10 days prior to detaching.
a b c d Figure 3: Mango scion budstick (a) cleft grafting (b, c) and wrapping the union (d)
Figure 4: Grafted mango seedlings covered with plastic hat (left), after hat removal (center) and top working of old mango
tree (right)
Pest management: Anthracnose disease and aphid insects may cause serious damage on mango
seedlings. Pesticide spray is needed to control the incidences.
Field management
Land preparation: The land should be cleared from live plants and plant debris. Then it should be
ploughed, harrowed, and leveled for planting. Deep ploughing is necessary in areas where hardpan is
expected. A land with a gentle slope facilitates irrigation and drainage.
Spacing: It depends on type of cultivars, grafting/ seedling, production area, and production system.
Grafted trees need narrower spacing than seedling trees. Some varieties have narrow canopy while
others have wider canopy, which needs wider spacing. Generally, square is more recommended than
other arrangements due to its convenience, and 7-9 m spacing between plants and rows is suggested.
Hole preparation: Usually 40x40x40cm3 holes are prepared for light and permeable soils 2-4
weeks before planting. However, for heavy and soils with a shallow hard pan 1x1x1m3 holes need to
be used. During hole preparation, kept topsoil and subsoil separately. Mix topsoil with welldecomposed organic matter and elemental fertilizers and fill back the hole with the mixture.
128
Planting: Planting can be done any time of the year if irrigation water is available; but it is
preferable to do it at the beginning of the rainy season. Planting in the evening or during cloudy
weather is preferred. During planting, care should be taken not to damage the root system. Keep the
graft union well above the ground level. Protect young plants from low temperature using shade.
Irrigation: Bearing trees need a rest period of about 3 months for flower induction. However, after
bloom trees must be irrigated adequately. The amount and frequency of irrigation depends on climatic
conditions, water holding capacity of the soil and age of trees. Young trees should be irrigated every
week while bearing trees must be irrigated at 10-15 days interval during the dry season.
Fertilization: The types and rate of fertilizer vary depending on soil fertility, age of trees and nonbearing or bearing trees. As a rule of thumb, a non-bearing mango tree needs 70g of nitrogen, 20g of
P2O5 and 65g of K2O per year. Then, the fertilizer rate will be doubled for the following years. Use
organic matter as source of nitrogen, but an excess application of nitrogen may lead to potassium
deficiency. Apply the fertilizer in two equal splits. On the other hand, a bearing mango tree requires
725g of nitrogen, 180g of P2O5 and 670g of K2O per year. During the year of heavy bearing, double
the nitrogen application. Apply the fertilizers once just after harvest. Micronutrient deficiencies are
not common in mango.
Pruning: Mango tree is naturally pruned, but at early stages, young trees (2-3 year-old) need to be
trained. Removal of the dead and diseased branches and pruning of intermingled branches to open the
center must be practiced once or twice a year. Moreover, prune branches that are too low or too high
on the trunk. Pruning has several advantages such as establishment of good frameworks, well-spaced
branches, and decrease breakage due to crop load.
Pest management
Fruit flies: They attack when fruits start ripening. They can be controlled by sanitation, early
harvesting, chemical spray and biological control.
Thrips: Attack buds and tender leaves of mango. It can be controlled by using biological agent
(fungus – Verticillium lecane) and chemical spray.
Scales: Attack branches, leaves, and fruits of mango. They can be controlled by using chemical
(Folimat) spray, and controlling ants with ash, greasy materials, or sticky-materials. Ladybugs eat
scales but ants eat the ladybugs and honey dew produced by scales. Hence, ants secure the scales from
Lady, bugs. If the ants are not there, scales produce much honeydew and die or eaten by ladybugs.
Mango weevil: It attacks seeds inside very small fruits, and causes small fruit drops just like
anthracnose and powdery mildew. The life cycle of weevil is about 40-50 days. The larva feeds itself
in the seed, then comes out to the flesh, and dies there causing the fruits look good externally but they
are not marketable. Hence, it is a very serious pest of mango and should be controlled by sanitation
(removing leaves) and spray with appropriate insecticide at the right time
Termites: Attack mango plants at all stages, but serious at seedling stages. They form anthills. They
can be controlled by digging and removing the queen and flooding the hole, and chemical such as
Diazinon, and Confidor spray gives full control. Confidor is applied in the rainy season or be sure it is
wet enough (2 ml/l).
Mole rats: It damages mango trees particularly at early stages. Flooding, chemical such as
Phostoxin, a leguminous plant that kills them, and traps can be used to control them in the field
129
Mango hopper: Are the most damaging insect during flowering. It hides under dark and becomes
active during flowering. Adults and nymphs suck the sap from the tender shoot and panicle, and
panicle withers and affects fruit set. Insecticides should be used to control the insect.
Mealy bug: Female lays eggs under soil around the tree trunk. Then, nymphs emerge and climb the
tree to suck sap from young shoots, panicles, and flowers pedicles. Affected parts dry and result in
substantial yield reduction. Control is effective at egg stage during hot months. Sticky bands (3045cm wide) around the trunk reduce the movement of nymphs.
Powdery mildew: It is a fungal disease, which is common in all mango-growing regions. It can
seriously damage the crop. It attacks all plant parts, but mostly damages young leaves, flowers, fruits,
and young shoots. The incidence is favored by high humidity, cloudy weather, and low night
temperatures. Fungicide spray effectively controls the disease. Spraying Bylaton immediately when
the plant is ready to flower and then repeated at 10-14 days interval for the first months before fruit
set could completely control the disease. Folicur and Bourdex mixture can also be used instead of
Bylaton. Pruning unnecessary branches also reduces the damage.
Anthracnose: It is also a fungal disease, which is very common in humid and high rainfall areas
(severe during rainy season). It affects leaves, shoots, inflorescence/ flower panicles and fruits. In
order to control the disease remove the dead and dry twigs, spray plants with copper fungicides (such
as Kocide and Antracol), and dip affected mature fruits in hot water (51oC) for 5-15 min before
storage. Resistant varieties such as Kent, Keitt, Tommy Atkins, and Vandyke can be used when
available.
Malformation
It is very serious problem in certain mango growing areas. There are two types of mango
malformations. These are vegetative malformation that is more common on nursery seedlings and
young plants, and floral malformation, which occurs on trees at the bearing stage, and affect
productivity. There is inverse correlation between temperature and the incidence of malformation.
Figure 5: Malformed mango fruit
Flowering and fruit drop in mango
Mango flowering is entirely dependent on climatic conditions. Flowering period is extended by low
temperature, but shortened as the temperature increased. It has two types of flowers, male and perfect.
Low temperature increases male flowers and hence reduce fruit yield. Mango is highly crosspollinated by different insects.
Fruit drop is extremely high in mango (up to 99%) due to lack of pollination, low stigmatic
receptivity, defective perfect flower extent of self-incompatibility, drought and lack of irrigation, and
high incidence of diseases and insect pests. Thus, regular irrigation and timely control of diseases and
insects reduce fruit drop. However, sometimes boron deficiency also causes fruit drop in mango.
130
Biennial or alternate bearing
It is yield reduction in alternate years, which means year of heavy fruiting followed by a year of little
or no fruiting. It is the most serious problem in mango production regardless of cultivars and areas.
Irregular bearing is caused largely by poor orchard management, but alternate bearing habit is
controlled by genes. Biennial bearing problem may be minimized by deblossoming, smudging, –
building up of slow fire, uses of chemicals like Ethrel and KNO3, pruning and thinning, and use of
promising regular bearing cultivars (but most of these cultivars are inferior in quality and late in
maturity).
Fruit ripening
The best fruits are that ripe on trees, but harvest unripe fruits for long distant market. During ripening,
mango fruit decreases acidity, increases sugar contents, and loses firmness and chlorophyll. Mango
fruits can ripen in about 5 days and become overripe in 7-8 days under tropical conditions. Place fruits
in layers and straw between two layers during ripening. Closed but well ventilated rooms are essential
for fruit ripening.
Harvesting
Stage of harvest has an important effect on fruit ripening and quality. The characteristic taste and
flavor of the cultivar cannot develop unless fruits are harvested at the correct stage. The possible
maturity indices include slight color development on the shoulders, when one or two ripe fruits fall
from the plant naturally, total soluble solids of at least 120 Brix, the ability to withstand a pressure of
1.7 to 2.0 kg/cm3, and when the specific gravity of fruits ranges between 1.01 and 1.02.
Shaking of the branches or hitting fruits with pole and dropping fruits from top results in internal
damage of the flesh during falling and spoils the appearance. A harvester can climb up the tree with a
collecting bag on his shoulder, but care is needed not to break the branches. Mango picker with a long
pole (bamboo) fitted with a cutting shear at the distal end and under which a fruit collecting net tied is
preferably used. However, harvesting of fruits from tall trees using mango picker is difficult.
Figure 6: Matured mango fruit ready for harvest
131
3. Postharvest Management I
NCREASING AGRICULTURAL PRODUCTION is one of the primary concerns in production
agriculture. A lot of effort has been made in areas related to food and cash crop production with a
great success stories in Ethiopia. However, increasing yield of biological products without value
addition using appropriate processing and preservation technologies will definitely leads to huge
nutritional and monetary losses. Further, promotion of the export market of the countries product
demands standard postharvest treatments and preservation technologies. This clearly indicates the
need for proper postharvest management related to all groups of food and cash crop such as fruits and
vegetables, cereals, pulses, oil crops, meat and meat products, coffee and tea, milk and milk products
as well as ornamental products.
When speaking about raw materials, especially those used by industrial firms and particularly cottage
industries, it must be considered that they may have two different origins: they may either grow
spontaneously or be cultivated. In both cases, the quality of the raw material is crucial to the
fulfillment of the goals pursued in the processing and preservation of the product, and determines the
level of profit. The material must therefore be of good quality and its industrial performance, which is
strongly dependent on the quality of the raw material, must be high. In addition to this, the raw
material must meet certain basic sanitary quality requirements.
As stated previously, the quality of a processed product essentially depends on the quality of the raw
material. On the other hand, the quality of the raw material also depends on the way that it is handled
during the production process. This is partly true in the case of species that grow in the wild. It is
partly true because harvest and post-harvest handling also influences the quality of a product.
However, not only the harvest and post-harvest processes have an impact on the quality of the raw
material. The entire production process is important, from planting or sowing to harvesting. In
addition, even before sowing, the selection of the soil, of the genetic material to be planted and of the
geographical location, will undoubtedly have a significant impact on the outcome, on the quality of
the raw material, and on the processed product. Of course, some species and specific cultivars or
varieties within them, are highly susceptible to environmental conditions, while others are much more
resistant to the conditions of the ecosystem in which they grow. Postharvest begins now of
separation of the edible commodity from the plant that produced it by a deliberate human act
with intention of starting it on its way to the table. The Postharvest period ends when the food
comes into the possession of the final consumer. Plants or plant parts continue to function
metabolically after harvest. However, their metabolism is not identical with that of the parent
plant growing in its original environment and therefore, they are subjected to physiological
and pathological deterioration and losses. "Loss" means any change in the availability,
edibility, wholesomeness, or quality of the food that prevents it from being consumed by
people. Causes of losses could be biological, microbiological, chemical, biochemical
reactions, mechanical, physical, physiological, and psychological. Microbiological,
mechanical, and physiological factors cause most of the losses in perishable crops. Other
causes of losses may be related to:
•
•
•
•
•
•
•
•
inadequate harvesting, packaging and handling skills;
lack of adequate containers for the transport and handling of produces;
storage facilities inadequate to protect the food;
transportation inadequate to move the food to market before it spoils;
inadequate refrigerated storage;
inadequate drying equipment or poor drying season;
traditional processing and marketing systems can be responsible for high losses; and
legal standards can affect the retention or rejection of food for human use being lax or unduly strict.
132
Losses may occur anywhere from the point where the food has been harvested or gathered up to the
point of consumption that is, harvest, preparation, preservation, processing, storage, and
transportation. Storage is an integral part of the food processing chain. While this source book
concentrates on the storage of basic commodities such as grains and root crops, major foods such as
oils, fish, and fresh produce are also covered. The storage of finished goods, which have been
processed, is outside the scope of this source book and is covered in other books in the series. The
food pipe line is given below to enable the reader easily understand the post harvest problems. Producer
Frost
Heat
Proper ocessing
Transport
Rain
Humidity
Storage
Contamination
Contamination
Processing
and
Packaging
Broken grain
Excessive dehulling
Trimming
Spoilage
Bruising
Breaking
Leakage
Insect
Molds
Bacteria
Rodents
inefficiency
Excessive peeling
Excessive trimming
Marketing
Unsafe foods
Quality losses
Excessive polishing
Birds
Sprouting
Rancidity
Overripening
Consumer
Fig.3.1. Schematic diagram of the post harvest food pipe line
The concept of water activity has been very useful in food preservation and on that basis, many
processes could be successfully adopted and new products designed. Water has been called the
universal solvent, as it is a requirement for growth, metabolism, and support of many chemical
reactions occurring in food products. Free water in fruit or vegetables is the water available for
chemical reactions, to support microbial growth, and to act as a transporting medium for compounds.
The higher the water activity the higher the physiological and biochemical changes taking place in
fruits and vegetables. Microbiological growth is also positively influenced by water activity in fruit
and vegetables. Enzymatic browning, enzyme activity, mold, and bacteria growth, yeast growth is
higher at increased level of water activity in fruits and vegetables.
In order to prevent or control spoilage the causes must be identified. Crop product spoilage is caused
by internal factors inherent or present within the potato, tomato, onion and pepper itself, and factors
present in the external environmental. Internal factors are natural substances known as enzymes,
which are contained in for example potato, tomato, onion, and pepper and are continually causing
changes in their composition. Up to a certain stage, such enzyme activity may be desirable as, for
example, in the activities, which cause tomato to ripen. But in potato, tomato, onion and pepper and
many other foods, the continued action of these enzymes causes rotting which make them inedible.
Enzymes also play an important role in nature, such as in the breakdown of very complicated plant
compounds. The simple elements formed are then used once again to nourish living things. The
external or environmental factors responsible for spoilage include living organisms (both plant and
animal) temperature conditions, moisture conditions, light, and oxygen.
The most important living organisms, which cause food, are: bacteria yeasts, moulds, insects and
rodents. Some kinds of bacteria moulds produce toxic substances in potato, tomato, onion, and pepper
without producing noticeable changes in the eating quality. These are very dangerous to health.
Insects and rodents not only cause great economic waste by consuming potato, tomato, onion and
pepper intended for human use, but in some cases, contaminate with hairs and faces.
133
Warm humid environments promote insect growth, although most insects will not breed if the
temperature exceeds about 35 °C or falls below 15 °C. In addition, many insects cannot reproduce
satisfactorily unless the moisture content of their food is greater than about 11%. The main categories
of foods subject to pest attack are cereal products and products derived from cereal products, other
seeds used as food; especially legumes, dairy products such as cheese and milk powders, dried fruits,
dried and smoked meats and nuts. As well as their possible health significance, the presence of insects
and insect excrete in packaged foods may render products unacceptable for markets, causing
considerable economic loss, as well as reduction in nutritional quality, production of off-flavors and
acceleration of decay processes due to creation of higher temperatures and moisture levels. Early
stages of infestation are often difficult to detect; however, infestation can generally be spotted not
only by the presence of the insects themselves but also by the products of their activities such as
webbing clumped-together food particles and holes in packaging. Unless plastic films are laminated
with foil or paper, insects are able to penetrate most of them quite easily, the rate of penetration
usually being directly related to film thickness. In general, thicker films are more resistant than
thinner films, and oriented films tend to be more effective than cast films. The looseness of the film
has also been reported to be an important factor, loose films being more easily penetrated than tightly
fitted films.
The penetration varies depending on the basic resin from which the film is made, on the combination
of materials, on the package structure, and of the species and stage of insects involved. The relative
resistance to insect penetration of some flexible packaging materials is as follows:
•
•
•
•
excellent resistance: polycarbonate; poly-ethylene-terephthalate;
good resistance: cellulose acetate; polyamide; polyethylene (0.254 mm); polypropylene (biaxially oriented);
poly-vinyl-chloride (un-plasticized);
fair resistance: acrylonitrile; poly-tetra-fluoro-ethylene; polyethylene (0.123 mm); and
Poor resistance: regenerated cellulose; corrugated paper board; kraft paper; polyethylene (0.0254 - 0.100
mm); paper/foil/polyethylene laminate pouch; poly-vinylchloride (plasticized).
Some simple methods for obtaining insect resistance of packaging materials are as following:
•
•
•
select a film and a film thickness that are inherently resistant to insect penetration;
use shrink film over-wraps to provide an additional barrier; and
Seal carton flaps completely.
Rats and mice carry disease-producing organisms on their feet and/or in their intestinal tracts and are
known to harbor salmonella of serotypes frequently associated with food-borne infections in humans.
In addition to the public health consequences of rodent populations in close proximity to humans,
these animals also compete intensively with humans for food. Rats and mice gnaw to reach sources of
food and drink and to keep their teeth short. Their incisor teeth are so strong that rats have been
known to gnaw through lead pipes and unhardened concrete, as well as sacks, wood and flexible
packaging materials. Proper sanitation in food processing and storage areas is the most
effective weapon in the fight against rodents, since all packaging materials apart from metal
and glass containers can be attacked by rats and mice.
Changes in temperature may cause direct damage to potato, tomato, onion and pepper in its outward
state, or may lead to indirect changes by helping spoilage agents such as bacteria and enzymes to
increase their activates. Direct damage by temperature is similar to the process of melting of fat when
exposed temperature above the melting point. Vegetables break down after freezing and the tissues of
all fruit and vegetables rupture after freezing and thawing causing them to be easily attacked by
bacteria to bring about spoilage. Temperature is the single most important factor in maintaining
quality after harvest. Refrigerated storage retards the following elements of deterioration in perishable
crops:
134
•
•
•
•
•
Aging due to ripening, softening, and textural and color changes;
Undesirable metabolic changes and respiratory heat production;
Moisture loss and the wilting that results;
Spoilage due to invasion by bacteria, fungi, and yeasts; and
Undesirable growth, such as sprouting of potatoes.
Water content, light and oxygen are other causes of spoilage. Preservation methods and techniques are
aimed at eliminating or restricting numerous factors that cause or promote deterioration or spoilage. In
order to maintain their nutritional value and organoleptic properties preservation is important. These
technical means can be summarized as follows:
Physical:
•
•
•
•
•
•
•
Heating;
Cooling;
Lowering of water content (drying/dehydration);
Concentration;
Sterilizing filtration;
Irradiation; and
Other physical means (high pressure, vacuum, inert gases)
Chemical:
•
•
•
•
•
•
Salting;
Smoking;
Sugar addition;
Artificial acidification;
Ethyl alcohol addition; and
Antiseptic substance action
Biochemical:
•
•
Lactic fermentation (natural acidification); and
Alcoholic fermentation
Inherent problems that affect the fruit and vegetables supply of man. Food preservation methods and
techniques are aimed at eliminating or restricting factors that cause or promote potato, onion, tomato
and pepper deterioration or spoilage. Inherent enzyme activity in potato, onion, tomato, and pepper is
prevented by heating the vegetables to temperatures, which destroy them and stop their activity.
Enzyme activity is also slowed down by cooling, freezing alternatively, air and light are shutoff from
vegetables, or chemicals are added to inhibit enzyme activity within them.
Controlling microorganisms (yeasts, mould, and bacteria), which cause fruits and vegetables spoilage
are killed by heat. In order that heat-treated fruits and vegetables are kept free- of these -agents, the
partial or complete elimination of these microorganisms is accompanied by further preventive
methods, to eliminate the possibility of recontamination. This is achieved by enclosing the fruits and
vegetables in tightly sealed containers to shut off air, moisture, and light. The process used to achieve
is known as packaging or canning for thermally processed products of fruits and vegetables.
In addition, the activities of microorganisms or their multiplication in fruits and vegetables like
potato, onion, tomato, and pepper may be slowed down or inhibited by refrigeration, or by freezing
and storage in the frozen state. The removal of water, known as dehydration, causes the water content
of the fruits and vegetables to be reduced to an amount, which does not support the growth or activity
of bacteria, yeasts, and moulds.
135
Chemical compounds in the form of preservatives are also added during disinfection, to control
growth and activities of bacteria, yeasts, and moulds. Salting smoking and the addition of sugar and
acids are chemical treatments also given (foods to control microorganisms.)
The principles of drying and treating food with chemicals like salt, smoke, sugar, vinegar, alcohol,
nitrate, nitrogen, antioxidationts, and organic fruit acids are used for food preservation. Chemical
compounds, which are used largely in traditional food preservation in topical Africa are salt, smoke
and in minor degrees, sugar. Salt is employed in the processing of fish and meat. The process is
usually known as curing. This is done to diminish perish ability and improve palatability. It also
increases the keeping quality of the product and may produce certain desirable changes in flavor and
color. Salt restricts the growth of bacteria and when sufficiently concentrated solutions are used,
bacteria are inhibited altogether. The proportions used in curing inhibit the development of spoilage
microorganisms and stop those, which help produce undesirable colors in food products. Salt hardens
the flesh of fish and meat and decreases its ability to absorb moisture although salt is a preservative,
foods per served by curing lose some nutrients. If salt is no considerably reduced or washed out of the
produce before consumption, it may cause health problems.
Smoking is one of the oldest methods used t preserve beef, mutton and goat meat. It is also use to
improve the keeping quality and palatability of fish. Dried beef and chicken may also b smoked. Flesh
which is to be smoked may be smoked nay be soaked in a strong solution of brine (salt solution) or in
a curing solution of salt and other seasoning before being smoked. Smoking affects flesh by surface
drying and penetrating the flesh where it deposits thick, brown, oil liquid called creosote. This
substance seen coated on foods, acts as an antiseptic.
In practice, preservation procedures aim at avoiding microbiological and biochemical deterioration,
which are the principal forms of deterioration. Even with all recent progress achieved in this field, no
single one of these technological procedures applied alone can be considered wholly satisfactory from
a microbiological, physico-chemical and organoleptic point of view; even if to a great extent, the food
value is assured. Thus, heat sterilization cannot be applied in order to destroy all microorganisms
present in foods without inducing non-desirable modifications.
Preservation by dehydration/drying assures microbiological stability but has the drawback of
undesirable modifications that appear during storage: vitamin losses, oxidation phenomena, etc.
Starting with these considerations, the actual tendency in food preservation is to study the application
of combined preservation procedures, aiming at the realization of maximum efficiency from a
microbiological and biological point of view, with reduction to a minimum of organoleptical
degradation and decrease in food value.
The principles of combined preservation procedures are:
•
•
•
•
•
•
avoid or reduce secondary (undesirable) effects in efficient procedures for microbiological preservation;
avoid qualitative degradation appearing during storage of products preserved by efficient procedures from a
microbiological point of view;
increase microbiological efficiency of preservation procedures by supplementary
means;
combine preservation procedures in order to obtain maximum efficiency from a microbiological point of
view, by specific action on various types of micro-organisms present; and
Establish combined factors that act simultaneously on bacterial cells.
Cold storage can be combined with storage in an environment with added of carbon dioxide, sulfur
dioxide, etc. according to the nature of product to be preserved. Preservation by drying/dehydration
can be combined with freezing, i.e., fresh fruit and vegetables are dehydrated up to the point where
their weight is reduced by 50% and then they are preserved by freezing. This procedure (freezedrying) combines the advantages of drying (reduction of volume and weight) with those of freezing
(maintaining vitamins and to a large extent organoleptic properties).
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A significant advantage of this process is the short drying time in so far as it is not necessary to go
beyond the inflection point of the drying curve. The finished products after defreezing and
rehydration/reconstitution are of a better quality compared with products obtained by dehydration
alone.
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Cold storage of dried/dehydrated vegetables in order to maintain vitamin C; storage temperature can be
varied with storage time and can be at -8 °C for a storage time of more than one year, with a relative
humidity of 70-75 %;
Packaging under vacuum or in inert gases in order to avoid action of atmospheric oxygen; mainly for
products containing beta-carotene;
Chemical preservation: a process used intensively for prunes, which has commercial applications is to
rehydrate the dried product up to 35 % using a bath containing hot 2 % potassium sorbate solution. Another
possible application of this combined procedure is the initial dehydration up to 35% moisture followed by
immersion in same bath as explained above; this has the advantage of reducing drying time and producing
minimum qualitative degradation. Both applications suppress the dehydrated products reconstitution
(rehydration) step before consumption; and
Packaging in the presence of desiccants (calcium oxide, anhydrous calcium chloride, etc.) in order to reduce
water vapor content in the package, especially for powdered products.
Preservation by concentration, carried out by evaporation, is combined with cold storage during warm
season for tomato paste (when water content cannot be reduced under the limit needed to inhibit
moulds and yeasts, e.g. aw = 0.70-0.75).
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•
Chemical preservation is combined with acidification of food medium (lowering pH);
Preservation by lactic fermentation (natural acidification) can be combined with cold storage for pickles in
order to prolong storage time or shelf-life; and
Preservation with sugar is combined with pasteurization for some preserves having sugar contents below
65%.
Quality has been defined as ‘fitness for purpose’ as it depends on who is the recipient in the marketing
chain. For example, farmers’ definition of quality is high yields and high returns; wholesalers and
retailers want products with a good appearance and long shelf life; and consumers refer to quality
products with a good appearance, flavor, and shelf life. This definition of quality has changed today
due to increasingly consumer-driven production/postproduction systems. It has been resolved in a
series of international conferences on ‘Managing Quality in Chain’ that quality is the composite of
product characteristics that impart value to the buyer or consumer. Therefore, products with the
following quality description are qualified accordingly:
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Low quality - not meeting consumer expectations;
Acceptable quality – satisfying consumer expectations; and
High quality – exceeding consumer expectations
Quality can be described using many parameters such as the following:
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Appearance, including size, color and shape condition and absence of defects;
Mouth-feel or texture;
Flavor or taste; and
Nutritional value
There are some methods that are used by growers and packers to improve the appearance of their
products in order to encourage more sales. As for other products, presentation and marketing can have
a positive influence on consumer sales. For example, in tomato and pepper, the fruits are packed in
pink plastic bags to enhance the color.
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It is important to note that customers that are dissatisfied with the internal quality of the product will
be reluctant to buy that product again. This means that repeat sales and total profits will decrease.
Appearance is only one part of fruit quality. Consumers buy with their eyes but they will only return
to buy again if the product tastes good too. The following are lists of some of the components that can
be used to measure the quality of a product
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Appearance;
Size: dimensions, weight, volume;
Shape and form: diameter/depth ratio, smoothness, compactness, uniformity;
Color: uniformity, intensity;
Gloss: nature of surface wax;
Defects: external, internal, morphological, physical, physiological, pathological or entomological;
Texture (feel): Firmness, hardness, softness, crispness, succulence, juiciness, mealiness, grittiness;
Flavor (taste and smell): Sweetness, sourness, astringency, bitterness, aroma, off-flavors and off-odors;
Nutritive value: Dietary fiber, proteins, vitamins and minerals; and
Safety: Naturally occurring toxicants, contaminants (chemical residues, heavy metals), mycotoxins and
microbial contamination
Quality loss can be because of growing conditions, metabolic stress or natural senescence,
transpiration and water loss, mechanical injury, infection by micro organisms and cardboard packaging.
Therefore, minimizing product respiration, water loss, mechanical damage, exposure to extreme temperatures,
injury, insects, pathogens and minimizing transportation time to marketing are important points to be considered
to maintain quality. The following sections will deal with postharvest technologies related to crop and livestock
based product qualities.
3.1. Postharvest Technology of Cereals and Pulses
Cleaning and grading
Cleaning and grading are the first and most important post harvest operations undertaken to remove
foreign and undesirable materials from the threshed grains and to separate the grains/ products into
various fractions. The comparative commercial value of agricultural products is dependent on their
grade factors. These grade factors further depend upon physical characteristics like size, shape,
moisture content, and color; chemical characteristics like odor and free-fatty acid content; and
biological factors like germination, insect damage. A mixture of seeds can be separated based on
difference in length, width/thickness, specific gravity, and surface texture/drag in moving air, color,
and shape. Cleaning in agricultural processing generally means the removal of foreign and
undesirable matters from the desired grains/products. This may be accomplished by washing,
screening, hand picking, separating, and winnowing. Grading refers to the classification of cleaned
products into various quality fractions depending upon the various commercial values and other
usage. Sorting refers to the separation of cleaned product into various quality fractions that may be
defined based on size, shape, density, texture and color.
Screening
Screening is a method of separating grain/seed into two or more fractions according to size alone. For
cleaning and separation of seeds, the most widely used device is screen. When solid particles are
dropped over a screen, the particles smaller than the size of screen openings pass through it, whereas
larger particles are retained over the screen or sieve. A single screen can thus make separation into
two fractions. When the feed is passed through a set of different sizes of sieves, it is separated into
different fractions according to the size of openings of sieves. Screens along with an air blast (air
screen) can satisfactorily clean and sort most of the granular materials. Hangers generally suspend the
screens, and when an eccentric unit oscillates this unit, they have a horizontal oscillating motion and
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at the same time a smaller vertical motion. These two motions cause grains to travel downward to the
screen and at the same time, the grains are thoroughly stirred during the passage.
Types of screens
In most screens, the grain/seed drops through the holes by gravity. Coarse grains drop quickly and
easily through large opening in a stationary surface. With finer particles, the screening surface must
be agitated in some way. The common ways are revolving a cylindrical screen about a horizontal axis
and shaking/ gyrating or vibrating the flat screens.
Revolving screen/cylinder sorter
Trommel or revolving screen is a cylinder that rotates about its longitudinal axis. The wall of the
cylinder is made of perforated steel plate or sometime the cloth wire on a frame, through which the
material falls as the screen rotates. The axis of cylinder is inclined along with the feed end to the
discharge end. Sizing is achieved by having smallest opening screen at the feed end with
progressively larger opening screens towards the discharge end. This type of sorter is simple and
compact with no vibration problem. Nevertheless, the capacity of cylinder sorter is lesser than the
vibrating screen of same size. Although it is an accurate sizer, it does not perform well with friable
material or in cases where particle degradation is undesirable because tumbling produces some
autogeneous grinding. The speed of rotation of the trommel is kept within the limit at which the
material is carried from bottom a distance equal to the radius of cylinder before it starts tumbling. The
inclination of cylinder sorter for dry granular materials is kept up to 125 mm/m. The capacity, bed
depth and efficiency of these screens can be changed by changing the speed of operation and the
inclination of cylinder. Effective screening area (not the total surface of cylinder) is calculated by
multiplying the length of cylinder by ⅓ of the diameter.
Shaking screen
Like the vibrating screen, shaker is a rectangular surface over which material moves down on an
inclined plane. Motion of the screen is back and forth in a straight line. Although in some cases
vibration is also given to the screen. Unlike the vibrating screen, the shaker does not tumble or turn
material enroute except that some shaking screens have a step-off between surfaces having different
size openings, so that there may be two or three tumbles over the full length of the screen. The shaker
is widely used as combined screen and conveyor for many types of bulk material. Rotary screen
Rotary and gyratory screens are either circular or rectangular decked. Their motion is almost circular
and affects sifting action. These are capable of accurate and complete separation of very fine sizes but
their capacity is limited. These screens are classified into two categories.
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Gyratory screens: This is generally a single decked machine. It has a horizontal plane motion, which is
circular at feed and reciprocating at the discharge end. The drive mechanism is at the feed end and it is
either a V-belt or direct coupling. The shaft that imparts motion to the screen is a counter balanced
eccentric. The shaft moves about a vertical axis. At the discharge end, most rotary screens have linkage to
the base frame, usually a self-aligning. Gyratory screens operate with screening surface nearly horizontal.
Circular screens: These are also rotary screens but their motion in horizontal plane is circular over the
entire surface. Similar to the gyratory screens the screening surface of circular screens are also little bit
tilted for allowing the material to move over them. Vibratory screen
For cleaning, grading and separation of agricultural granular materials vibratory screen cleaners are
very popular. For separation of undesirable foreign materials from feed mass and sorting the materials
into various size groups according to desired quality standard or grades, the vibratory screens are
extensively used. Accuracy in separation based on size is very important, as small difference in size
may be able to separate undesirable or low quality matter.
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An eccentric unit agitates the vibratory screens. When materials to be separated are put on a vibratory
screen, because of its vibration, materials are also agitated and separated during their transit over the
screen. The eccentricity is usually of two types, a shaft to which off center weights are attached, and a
shaft that itself is eccentric or off centered. In the latter case, a flywheel for providing uniform
vibration balances the eccentricity. Most vibrating screens are inclined downward from the feed end.
Vibration is provided to the screen assembly only and the body and other surrounding structures are
isolated from vibration. Generally, up to three decks are used in vibrating screens. The capacity of
vibrating screen is higher than any other similar sized screen and is very popular for cleaning and
grading of granular agricultural products. The vibration of screen is responsible for performance of
the following functions:
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it helps in providing passage to particles through the openings of screen;
it restricts clogging of the screen by particles that become trapped in the opening
because of vibration the particles are stratified over the screen surface and each particle has a chance to
meet the screen opening; and
a continuous flow of particles along the screen is possible.
Screen openings
Screens are generally constructed by perforated sheet metal or woven wire mesh. The openings in
perforated metal sheets may be round, oblong or triangular as shown in Fig. 4.2. The openings in wire
mesh are square or rectangular. The size and shape and their combination of the screens available in
market are identified by some trade numbers.
Fig. 4.2. Perforated metal screens: a. round holes, b. oblong holes and c. triangular holes.
Perforated metal screens
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Round openings: The round openings in a perforated sheet metal screen are measured by the diameter
(mm or in.) of the openings. For example, 1/18 screen has round perforation of 1/18 in. in diameter or 2mm;
Oblong openings: The oblong or slotted openings in a perforated sheet metal screen are designated by
two dimensions, the width and length of the opening. While mentioning oblong openings the dimension of
width is listed first then the length as 1.8 x 20 mm. Generally, the direction of the oblong opening is kept in
the direction of the grain flow over the screen; and Triangular openings: There are two different systems used to measure triangular perforations. The most
commonly used system is to mention the length of each side of the triangle in mm, it means, 9 mm triangle
has 3 equal sides each 9 mm long. The second system is to mention openings according to the diameter in
mm that can be inscribed inside the triangle. This system is identified by the letter V as 9V, 10V.
Wire-mesh screens
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Square mesh: The square openings in wire mesh are measured by the number of openings per inch in
each direction. A 9 x 9 screen has 9 openings per inch (Fig. 3.2); and.
Rectangular mesh: the rectangular openings in wire-mesh screens are measured in the same way as
square wire-mesh screen. A 3 x 6 rectangular wire-mesh screen will have 3 openings per inch in one
direction and 6 openings per inch in the other direction The rectangles formed by the wire-mesh are kept
parallel to the direction of gram flow (Figure 4.3 and 4.4). 140
Fig. 4.3. Wire mesh screen
Fig. 4.4. Wire mesh screen
(Rectangular opening)
(Square opening)
The basic purpose of any screen is to separate the feed consisting of a mixture of particles of different
sizes into two distinct fractions. These fractions are the underflow, the particles that pass through the
screen; and the overflow or oversize, the materials that are retained over the screen. A screen can be
termed as ideal screen, which separates the feed mixture in such a way that the largest particle of
underflow is just smaller than screen opening, while the smallest particle of overflow is just larger
than the screen opening. However, in practice no screen gives perfect separation as stated above, and
is called actual screen. The underflow may contain material coarser than screen size, whereas the
overflow may contain smaller particles than screen size.
Equipment for cleaning, grading and separation
It is very difficult to differentiate among the processes of cleaning, grading, and separation because all
of these are carried out simultaneously with the common procedures. The operation of cleaning,
grading, and separation of the products are performed by exploiting the difference in engineering
properties of the materials. These products may be used either for food or seed purposes. Various
types of cleaning, grading, and separation equipment have been designed and developed based on
properties of product to be handled. Thus, this equipment can be classified based upon following
characteristics of the material.
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Size;
Shape;
Specific gravity or weight;
Surface roughness;
Aerodynamic properties;
Ferro-magnetic properties;
Color; and
Electrical properties
Separation based upon size
Screen cleaners/graders
It performs the separation according to size alone. The mixture of grain and foreign matter is dropped
on a screening surface, which is vibrated either manually or mechanically. A single screen can make
the separation into two fractions. The screening unit may be composed of two or more screens as per
the cleaning requirement mounted one on the top of another. The equipment is made of mild steel.
The separation takes place due to difference in size of grain and foreign matter. The cleaner is
operated by hanging on an elevated point with the help of four ropes. Grain is fed on the screening
surface in batches. The screens can be changed as per the grain to be handled. The cleaner is swung
back and forth until all the grain is screened. The cleaned grain is retained by the bottom sieve, which
can be discharged by pulling a spring-loaded shutter. Impurities of larger size, stubble, chaff etc. are
retained on the top sieve and can be removed easily. Downstream from the bottom sieve consists of
dust, dirt, broken, shriveled grain, etc. drop down during the operation.
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A typical seed grader consists of seed roller for controlling the feed rate, set of three sieves, pulley,
eccentric system, outlets, frame, and electric motor. The sieves are detachable and can be replaced by
suitable sieves if other round grains are to be graded. The seed is put into the hopper and it is dropped
onto the sieve through feed rollers. Sieves are vibrated through an eccentric system. Graded seeds are
collected through three different spouts. The machine is suitable for grading of food grains.
Disk separator
The disk separator separates materials based on difference in length of various constituents. The
separator has pockets or indentations on its surface. When the machine is operated, the smaller sized
materials are caught in the pockets while the larger ones are rejected. It is used especially for
removing dissimilar material like wheat, rye, mustard; barley from oats. The indent disk separator
consists of a number of disks in series fitted on a shaft inside a close housing, which revolves on a
horizontal axis. The pockets are undercut on each disk as shown in Fig. 4.5. As the disk revolve
through a mixture of grains, the pockets pick up short grains and drop them in a trough at the side of
the machine.
Fig. 4.5. Disk separator The desirable or undesirable materials not lifted by the disks are conveyed through the disk spokes to
the end of the machine and passed out through the tailing opening. A number of distinct separations or
grading of the grain of varying length can be made in a single machine by installing combination of
disks having pockets of different sizes. The mixture first passes through the disks with small pockets
and then disks with pockets progressively larger from inlet to discharge If only one separation has to
be performed; combination of disks of same size of pockets is used in the machine to increase its
handling capacity. The removable vanes are provided with spokes of the disks, which serve the
purpose to move grains through the machine agitate them and bring them in contact with the pockets
The disk pockets are made of three basic shapes of various sizes. The 'R' pocket derived its name from
'rice' and designed to remove broken rice grains from whole grains. It has a flat and horizontal lifting
edge and round leading edge. It rejects round grains but lifts out cross-broken or flat grains. The ‘V’
pocket derived its name from ‘Vetch’ and designed to pick up and remove round shaped grains. It has
a round lifting edge winch tends reject tubular or elongated grains. Disks with other letter
designations are designed to perform specific separations.
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Separation based upon shape
Indented cylinder separator
The indented cylinder separators also separate the materials based on relative lengths like disk
separators. It consists of a horizontal rotating cylinder, which has indents. on the inside surface. The
indents are closely spaced and hemispherical in shape (Figure 4.6). When the mixture of grain is fed
into one end of the cylinder, short grains are picked up by the combined effect of fitting into the
indents and centrifugal force. These grains are dropped into an adjustable trough inside the cylinder
near the top of rotation. A screw conveyor is provided in the bottom of the trough, which conveys the
material. Generally, the cylinder is kept at slight inclination to facilitate gravity flow of lone grains in
the cylinder. The cylinders with indents of different sizes are available, but the size of all indents in a
particular cylinder is the same. For different separation needs, indented cylinder has to be changed.
The speed of operation of cylinder and the position of adjustable trough are important adjustments for
obtaining the desired level of separation. Since the centrifugal force helps to handle the grain in the
pocket, it affects the distance traveled by grains before they fall. The excessive speed will not allow
grains to drop from the indents. Too slow speed will not lift short grains from the mixture. The
position of separation edge of the adjustable trough should be such that it can catch the desired
fraction of the dropping grain.
Fig. 4.6. Indented cylinder separator
Inclined draper
The separation by inclined belt draper takes place due to difference in shape and surface texture of the
material. This technique of separation is used when all other methods fail. The mixture to be separated
is fed over the centre of an inclined draper belt moving in upward direction. The round and smooth
grains roll or slide down the draper at faster rate than the upward motion of the belt, and these are
discharged in a hopper. The flat shaped or rough surfaced particles are carried to the top of the
inclined draper and dropped off into another hopper (Figure 4.7). The belts of different degrees of
roughness may be used as a draper for separate materials. If rolling tendencies of the grain are
predominant, the rough canvas belt may be used. The smooth, plastic belt may be used in case sliding
action is desired for the lower action. Feed rate, speed of speed of draper and angle of inclination are
other important variables for effective separation of dissimilar materials. The feed rate is kept low
enough to give opportunity to each grain for separation. The speed of the draper may be varied to
simulate with the length of incline. The angle of inclination is adjusted to assure rolling or sliding of
the desired lower fraction. To increase the capacity of the separator, number of belts may be used one
above another in a single machine.
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Fig. 4.7. Inclined draper
Spiral separator
The spiral separator separates the grains as per their roundness. The main component of the separator
is a stationary, open screw conveyor standing on one end (Figure 4.8). The mixture is fed at the top of
the unit. The round materials of the mixture pick up speed as they slide or roll down the inclined
surface until their centrifugal force become sufficient to throw them in the outer helix; while the nonround materials are caught in the inner helix and are discharged through a separate spout. There is no
moving part in the spiral separator. The rate of feeding is the only adjustable component. The feeding
should be such that each grain/particle rolls independently for effective separation. The main
limitation of the spiral is lack of flexibility. Separation of mustard, rape, soybean, wild peas, or other
round seeds can be performed from wheat, flax, oats etc. This device is less versatile as compared to
other mechanical cleaners, but it is simple, inexpensive, and quite useful for seed cleaning purposes.
Fig. 4.8. Spiral separator
Separation Based upon Specific Gravity
Specific gravity separator
The specific gravity separator makes the separation according to difference in density or specific
gravity of the materials. This separator works on two principles, i.e., the characteristics of grains to
flow down over an inclined surface, and the floatation of the particle due to upward movement of air.
The main part of the device is a triangular-shaped perforated deck. The deck is properly baffled
underneath to ensure uniform distribution of air over it. The pressure or terminal velocity of the air
rising through the deck is controllable very closely within a wide range (Figure 4.9). The mixture of
grain is fed into the feed box. The air is blown up through the porous deck surface and bed of the
grain by a fan at such a rate that the material is partially lifted from contact with the deck surface. The
lightest materials are lifted to the top of the stratified mass. The air does not lift the heavier particles.
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The stratified mass moves along the direction of conveyance due to oscillating motion of the deck and
is discharged at the right edge of the deck.
Destoner or Stone separator
The stone separator is a form of specific gravity separator. It separates the grain mass into two
fractions as per the difference in specific gravity. The mixture is fed onto the centre of a perforated
deck (Figure 4.10). The air coming through the deck from bottom stratifies the materials while the
reciprocating action of the deck separates the heavy particles from the lighter particles. The heavier
materials move towards the top end of the deck whereas the lighter particles are discharged from the
low end of the deck, without any middling product. The separation can be controlled by adjusting the
feed rate, slope of the deck, deck vibration and the airflow rate.
Fig. 4.9. Specific gravity separator
Fig. 4.10. Stone separator
Pneumatic and aspirator separators
The pneumatic separation is based on the difference in aerodynamic properties of various constituents
of the mixture. The aerodynamic properties of a particle depend upon its shape, size, density, surface
and orientation with respect to air current. Both the aspirator and the pneumatic separator use terminal
velocity of the grain to separate different fractions. This refers to the velocity of air required to
suspend particles in a rising air current. In a pneumatic separator, the fan is placed at the intake end of
the machine that creates higher pressure than the atmospheric pressure. The high-pressure air blast
separates the materials. The mixture of products is introduced into a confined rising air stream, the
particles with low terminal velocities are lifted by the air current whereas the particles with higher
terminal velocities than air velocity fall down. The air velocity can be adjusted by altering the speed
of fan or by changing the opening of air inlet. The aspirator has a fan at the air discharge point, which
creates a vacuum or negative pressure within the machine. The scalping separator is a type of
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aspirator separator in which rough separation is performed. The mixture of the grain is dropped into a
rising air column, which has a velocity slightly lower than the terminal velocity of the heavy grains.
The leaves, trash, and lighter particles rise with the air and are deposited in an enlarged settling
chamber. The denser, plumper grains fall through the incoming air into a container.The fractionating
aspirator is another type of separator. The mixture of grain is fed into the lower end of an expanding
air column, the heavy grains fall against the airflow while the lighter particles are lifted. The grains
with high terminal velocity are dropped in the expanding column. The lighter fractions of grains are
discharged as per the relative weight through different outlets positioned in the column. Thus, the
mixture is separated into various fractions (Figure 4.11).
Fig. 4.11. Diagram of pneumatic separator; 1. Undesirable material removal, 2. Uniform feeder, 3. clean grain out let, 4. Centrifugal
blower, 5. Control for air intake
Separation based on fluidization technique
The fluidized bed cleaner/separator makes the classification of seed due to difference in density and
size. This device is suitable for cleaning lighter seeds like cabbage, radish, lettuce, carrot, onion, grass
seeds etc. When an air current is passed vertically upward through a perforated deck containing a bed
of granular materials, various phenomenon occur (Fig. 4.12). At low airflow rate, the bed remains
inert, causing pressure drop in the air flowing through the bed. As the airflow rate increases, a stage
are reached called the quiescent stage when the bed begins to expand to the extent of 10% volume
increase. The mobility of the bed depends on the shape of the particles but the external vibration is
applied to produce a mobile fluid bed. At this stage, the surface may be observed to bubble, small
particles may be observed to rise and some general circulation of the bed may occur. These are known
as boiling and bubbling beds. Classification of the beds by density or particle size may occur at these
stages. Further increase of airflow rate may cause slugging of the bed. The surface of the bed at the
slugging stage is turbulent and uneven preventing any classification. When the airflow rate is further
increased, the bed of cohesive particles may pass into a channeling stage. Finally, any increase in the
airflow rate may lead to the formation of the spouting bed. In order to achieve separation the bed
should be boiling or bubbling.
Fig. 4.12. Fluidized bed separator.
The seeds fall from the hopper either directly onto the deck or onto a vibratory feeder and from there
onto the deck. A fan feeds a plenum chamber beneath the porous deck to fluidize the seeds
immediately. The channel slopes are kept between 10 and 20° so that the fluidized seed flows down
the slope; while classifying in the normal way. When it reaches the bottom of the deck after a
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residence time of about 1-5 seconds the fine chaff and dust. are collected at the top and the good seeds
in the lower layers. The channel is built in the form of a converging taper so that the bed would
become deeper at the discharge end, thus increasing the precision of separation. For free flowing
seeds, the amount of vibration is negligible. As the seed flows freely from the end of the channel a
splitter is carefully positioned to separate the rubbish and leaving the good seed to pass .
Separation based upon magnetic property
Magnetic separator
The magnetic separator performs separation based on surface texture and stickiness properties of the
grain. Since the grains do not contain any free iron, therefore, are not attracted by the magnet. A
selective pretreatment of mixing finely ground iron powder to feed mass is given. The grain mixture is
fed to a screw conveyor or other mixing device that tumbles and mixes the grain with a proportioned
amount of water. Due to moisture, iron powder adheres to rough, cracked, broken, and sticky seed
coats. Moisture does not remain on smooth grains so no iron powder adheres to smooth surfaced
grains. The grain mixture is fed onto the top of a horizontal revolving magnetic drum, the smooth
grains that are relatively free of powder fall along the drum simply by gravity. The materials with iron
powder are attracted by the magnetic drum and stick to it and are removed by rotary brush or break in
the magnetic field as shown in Fig. 4.13. Most magnetic separators have two or three revolving
magnetic drums operating in a series. The grain mixture is passed over these magnetic drums to
increase the efficiency of operation. The extent of difference in seed coats, amount of water mixed,
and amount of iron powder and thoroughness of powder-water mixing operation affect the degree of
successful separation by magnetic separators.
Fig. 4.13. Magnetic separator; 1. Feed hopper, 2. Water spray, 3. Iron powder mixing, 4. Magnetic drum
Quality testing of grains
Because of the increasingly sophisticated and complex automated management systems in modern
mills, the commercial trade of grains requires stringent quality standards. Specific raw material
quality is required to meet the needs of these processes. This enables to maximize throughput and
yield and to prevent any interruptions in production caused by unexpected variations in the grain
quality. Commercially, there is a need to provide grains that conforms to strict quality standards,
which are nationally and internationally accepted and capable of verification and standardization.
Many of the quality tests used have not been able to be standardized, because they have been
incapable of being validated by reference to known reproducible standards. In a commercial sense, the
term "quality" is defined as fitness for purpose or as fulfilling the requirements for a particular
process. Therefore, there can be no absolute definition of quality, because it varies according to the
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requirements of the process and the ultimate end use of the product. For example, in selecting wheat
the miller needs to know how well particular sample wheat will perform in the mill in terms of the
final amount of flour obtained from the wheat, the ease of separation of bran from endosperm, its
breakability, and the flow properties of the flour. Bakers will have different requirements from the
miller, particularly whether the flour will produce good bread and give no problems in processing in
the bakery. In effect, a quality test is trying to predict the performance of the grain in later processing
during milling and other final products. Such predictions were generally obtained by trial and error in
the first place through generations of experience and empirical correlations between simple tests and
the final product performance. For example, an experienced miller will be able to predict the "quality"
of a wheat sample by its smell and appearance and by biting and chewing a few grains of wheat. The
act of biting and chewing encompasses the whole process of milling and mixing the flour with water
to produce dough. Moisture
Moisture content is regarded as one of the most important quality characteristics of grains, mainly
because it directly affects the specific weight and value of the grain (buyers do not want to pay for
water) and its effect on the microbiological stability during storage. When grains are first harvested,
they can have wide range of high moisture content, depending on climatic conditions, and therefore
need to be dried. Grains are dried to safe storage temperature directly after harvesting. Optimum
storage moisture for wheat, for example, is less than 12.5%, whereas optimum-milling moisture is
between 14% and 17%, necessitating the addition of water (conditioning) to the wheat before milling.
The distribution of water in samples of grains is frequently inhomogeneous, making sampling
techniques important. Different tests involve different methods of sample preparation with, for
example, tests stipulating varying degrees of grinding that will result in variations in water losses
during grinding. Moisture content determination methods
There are several methods for determination of moisture content of agricultural
products. For
determination of moisture content of a particular product, the choice of method depends on many
factors, they are:
•
•
•
•
•
•
the form in which water is present in the product;
the relative amount of water present;
the rapidity of determination;
accuracy of method;
product's nature whether easily oxidised or decomposed; and
the cost of equipment used.
Moisture content is determined mainly by two methods, i.e., direct, also called as primary and
indirect, and called as secondary methods. The accuracy of moisture content determination by direct
methods is high; hence, these methods are used by research workers. The moisture content values
obtained by direct methods are used to calibrate all the indirect type moisture-measuring devices. The
direct methods of moisture determination are time consuming therefore, such methods are not very
much useful for determination of moisture in field, or warehouses. Indirect methods are faster and
mostly employ the electrical properties of the grains. The determination of moisture is empirical
method because the various moisture determination methods measure more or less the water present
in the product. Thus, the experimental conditions or method governs to some extent, the amount of
moisture obtained.
Direct methods
•
Air oven method: When the moisture content of grains is up to 13%, 2-3 grams representative ground
samples of grains are placed in an air-oven. The temperature of the oven is set at 130°C and the samples are
kept in oven for 1-2 hours. Afterwards, the samples are taken out and placed in a desiccator to cool down.
The drop in the weight of grain is measured based on its initial weight;
148
•
In other method, 25 to 30 grams of ungrounded representative samples of grains are taken and placed in an
air-oven at 100°C temperature. The samples are kept in it for 72 to % hours. Afterwards, the samples are
taken out from oven placed in a desiccator to cool down to room temperature. Moisture content of samples
is measured based on drop in weight from initial weight of sample;
•
Vacuum-oven method: In this method, 2-3 grams of representative sample of ground material is placed
in a vacuum-oven (25 mm vacuum) and dried at 100°C for 72-96 hours. Afterwards, the samples are
weighed. The drop in the weight of grain is measured based on its initial weight;
The equipment generally used for determination of moisture content by air oven method are given below.
•
o
•
•
Moisture dishes: For moisture measurement, the moisture dishes should be made of heavy gauge aluminum
sheet metal. The moisture dishes may not be easily damaged by dents. The dishes should have tight covers. Same
numbers should be marked on the dish and its cover. Before use, the moisture dishes should be dried in an oven for
one hour thereafter these should be weighed.
Desiccator: The desiccator should be properly airtight and have active absorbent inside. o
Oven: Convective type of dryers is mostly used for moisture determination. These are sufficiently heat
resistant. These ovens maintain predetermined temperature. The oven should have arrangements for proper
air circulation, transferable perforated toys and a suitable thermometer sensitive enough to show 0.5°C
temperature difference. These ovens are equipped with proper temperature control system. The oven should
be run for few hours prior to their use for moisture determination;
Balance: An analytical balance should be used to determine the moisture content of product correctly. The
balance should be sensitive enough to weigh up to 0.01 grams.
The temperature and time combination for various grains/seeds are given in Table 4.1.
Table 3.1. Oven temperature and heating period for moisture content determination
Seed
•
•
Oven temperature, °C
Heating period, hour
Wheat
130
19
Sorghum
130
18
Maize
130
72
Mustard
130
04
Sunflower
130
01
Safflower
130
03
Beans
103
72
Barely
103
20
Brown-Duvel fractional distillation method: The moisture content of products is measured by
fractional distillation method. The method is recognized as an official method for determination of
moisture content. Hundred gram whole grains along with 150 ml. of mineral oil is taken in a flask. The
sample is boiled. Moisture from the sample is thus evaporated, collected, and condensed in a graduated
cylinder. The milliliter of moisture collected shows the percentage moisture content. The determined
moisture content is on wet basis. In this method, the temperature of mineral oil in flask should reach to
200°C within 26 minutes. The time required for moisture determination is about 30 minutes. If the
temperature of mineral oil reaches to desired temperature within time, the moisture content determination is
found to be accurate. When samples of grains are taken from bulk, a variation in moisture content to the
tune of 1 to 1.5% is possible;
Infrared method: In this method, grain moisture content is directly measured by evaporation of the
water from a sample of grain with an infrared heating lamp. A commercial infrared moisture meter is also
available in market. The instrument consists of a balance, a pan counter balanced by a fixed weight and a
variable length of weighing chain. An infrared lamp is mounted on an arm above the pan with a provision to
change its height. A scale calibrated in percentage moisture content is incorporated in the stem of the
instrument. At the end of the test, when the balance is zeroed, a direct reading of moisture content is
149
obtained. The sample of grains may be unground, but when ground sample is used, the time needed to
evaporate the water is reduced.
Indirect methods
Electrical resistance method: The electrical conductivity or resistance of a product depends
upon its moisture content. This principle is employed in resistance measuring devices. The universal
moisture meter measures the electrical resistance of the grain at a given compaction. The electrical
resistance apart from compaction is also affected by grain temperature and impurities present in the
sample. Such moisture meters are calibrated for grain/seed types, degree of compaction and
temperature. Universal moisture meter gives accurate readings of moisture content on wet basis.
Dielectric method
Such devices measure the dielectric constant of grains. The grains are filled in chamber. The sides of
the chamber are formed by the plates of a condenser between which a high frequency current is
passed to measure the capacitance of the sample. The capacitance varies as per the water present in
sample, the degree of compaction and the grain temperature. The electrical properties of grain are
temperature dependent. Since the measurement of grain, temperature is difficult, therefore/ambient air
temperature is often used. This may result a source of error because of the difference between air and
grain temperatures.
For measuring moisture content, the major components are water and dry matter. The amount of water
or dry matter in the grain is often expressed in percentages. There are two methods of calculating this
percentage. Grain marketing institutions use the wet-basis (wb) method for calculating and expressing
moisture content; engineering and scientific researchers use the dry-basis (db) method. The definitions
of each may be confusing, but the procedure for converting moisture content from wet basis to dry
basis or from dry basis to wet basis is simple. Dry matter consists of the components of grain that are
not water. For grains such as shelled corn (maize) and wheat, the dry matter is primarily starch. For
grains such as soybeans and canola, the dry matter includes a significant amount of oil and protein.
For determining moisture content, the exact components of the dry matter are not important. The grain
trade defines moisture on the wet basis because it directly expresses the amount of water in the grain
as a percent of the total grain weight. Wet- basis moisture content (Mw) may be calculated as follows:
As grain dries the weights used for both the numerator and the denominator of this equation change.
Thus, the amount of water removed by a single percentage point change in wet-basis moisture content
will decrease as the grain becomes drier. Moisture content values expressed as wet-basis cannot be
directly added or subtracted to find a weight change attributed to drying. Engineering and scientific
researchers often prefer to use dry-basis moisture content, because the amount of water removed by a
single percentage point of dry-basis moisture content change remains constant for all ranges of
moisture content. Dry-basis moisture content (Md) may be calculated as follows:
150
Conversion of dry-basis moisture content to wet-basis moisture content, expressed as a percentage,
may be calculated as follows:
Conversion of wet-basis moisture content to dry-basis moisture content, expressed as a percentage,
may be calculated as follows:
Size and shape
Size and shape of grains have long been associated with the extraction rate (the total proportion of
white flour extracted from a given weight of wheat). The surface area of a given grain is roughly
inversely proportional to the average diameter of the grain. The larger the grain, the greater would be
the ratio of volume to surface area. This is because of the well-known cube-square relationship
between volume and surface area of a body: as an object increases in size, the volume increases as the
cube of its length or radius, whereas the surface area increases only as the square of its radius. Grains
vary in size and shape, and it is therefore expected that large, plump grains will have a lower
proportion of surface area (bran) to volume (endosperm) than small thin grains. This should then have
an impact on the maximum extraction, with large round grains producing more white flour per unit
weight than small grains. Table 3.3 gives typical dimensions found among cereal grains and Table 2.4
shows typical extraction rates produced by wheat grains of various sizes throughout break roll milling.
Size fractions of grains can be determined by passing the wheat through vibrating sheets containing
slots of decreasing width.
Most grading systems rely on visual inspection and comparison of the morphology of grain samples.
This highly subjective procedure requires considerable training and expertise to achieve consistent
results and is incapable of independent verification by reference to quantifiable standards. Until
recently, for example, comparison of grain morphology was sufficient to discriminate hard from soft
wheat varieties. Certain new varieties exhibit the morphological characteristics of soft wheat but
possess the milling and baking characteristics of hard wheat. Various objective instrumental
measurements of grain characteristics have been developed, in particular for hardness and grain
morphology. Digital image analysis has been used to quantify both the shape and color of samples of
wheat grain and to discriminate between different varieties and has now been developed for use
commercially to measure the size and color of wheat grains. Works are underway to extend the same
technology for use on rice.
Table 3.2. Typical dimensions (mm) of cereals grains
Cereal Type
Wheat
Durum
Barely
Rye
Oats
Maize
Sorghum
Length
5.0-8.5
6.0-8.5
7.5-9.7
5.0-10.0
9.5-11.0
8.5-10.6
4.7-5.6
Width
1.6-4.7
2.8-4.0
3.5-3.8
1.5-3.5
2.5-3.1
7.5-10.0
4.0-4.6
Thickness
2.0-3.4
2.4-3.2
2.4-2.9
1.5-3.0
1.8-2.3
4.3-6.5
2.0-2.6
Table 3.3. Percentage Extraction of White Flour Obtained from Wheat
Grains of Various Sizes through Break-Roll Milling
Break No.
Large
Medium
I
II
37.14
49.25
24.80
44.38
151
Small
20.57
42.11
Impurities
On arrival at the mill, grains are inspected thoroughly for impurities such as damaged, shriveled,
diseased grains, and other contaminants. Such impurities in wheat are generally known as screenings
in the United Kingdom, dockage in the United States, and besatz in continental Europe, although each
term has a slightly different meaning because of the use of different methods to separate and measure
the total proportion of impurities. Admixture is a term used to describe all material that is not whole
grain. Screenings are determined by passing the grain through slotted or mesh screens, with the size of
the slots depending on the end use of the grain. The principal reason for measuring the proportion of
impurities is to ensure the grain conforms to the specifications stated by the seller and to ensure that it
is not contaminated or infested before storage. If the batch fails to meet the necessary quality
requirements, the batch may be rejected or adjustments to the price paid can be negotiated. For
example, a discount of up to 3% for each 1% of impurities detected is specified for stocks of wheat
purchased for European Union intervention purposes.
Smell
Smell is important in the initial assessment, for instance, of wheat quality, because it can indicate the
presence of fungal or insect contaminants. Problems arise in such assessments, because they are
highly subjective and variable and because different individuals have highly variable responses to
taints and odors. New methods are being developed that attempt to quantify smells and odors by use
of thin-film conducting polymer and metal oxide sensors, as in the "electronic nose.”
Specific weight
Specific weight, also known as test weight or hectoliter weight is one of the most widely used
indicators of wheat quality in commercial trading. It is measured by the weight of grains required to
fill a container of known volume under controlled conditions. Specific weight is described as
kilograms per hectoliter, known as hectoliter weight. Specific weight is associated with extraction—
the amount of flour produced per unit weight of wheat—although it may not always be a reliable
indicator because of its susceptibility to extraneous factors such as grain packing density, grain shape
and size, grain surface condition, impurities, moisture, and disease. The packing density will be
affected by vibrations in the laboratory, variations in handling, and the type of equipment being used
to contain the volume. Hook (1984) investigated the relationship between specific weight and flour
yield using UK wheat varieties. This work and numerous previous publications cast doubt on the use
of specific weight as an indicator of flour yield. Correlations between specific weight and yield were
poor and influenced by variety, growing site, and year. Both grain moisture and its moisture history
strongly influence specific weight. Because of these factors, the use of test weight has been much
criticized and cannot therefore be considered a reliable indicator of milling quality or extraction.
Thousand grain weight
Thousand-grain weight is usually expressed as the weight of a thousand grains of wheat in grams. It is
normally determined automatically by electronically counting and weighing 1000 grains of cleaned
wheat. It is used to predict how much flour will be extracted from a given weight of wheat. Thousandgrain weight is probably more highly correlated with milling extraction, because it is directly related
to grain size, which is known to be related to extraction. Typical values of 1000-grain weights of the
main cereals are presented in Table 3.6. The density of wheat is here defined as the density of the
endosperm, rather than the apparent density or specific weight of bulk wheat samples, which, as
described in the section on "Specific Weight," is highly dependent on many factors other than the
wheat endosperm density. The density of endosperm as measured by most methods will normally
contain the combined contribution of air pores (2%-13%) and the solid endosperm material. The
density of wheat will be largely influenced by the porosity and the packing of the endosperm
components within the grain and therefore will be closely associated with physical hardness,
virtuosity, and milling performance of wheat (Table 3.5). Table 2.7 shows typical density ranges
found in common cereals
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Table 3.4. Typical 1000 grain weights
Grain
Maize (corn)
Wheat
Rice (white) medium
Sorghum
Barley (with hulls)
1000 Grain Weight (g)
300
40
30
20
40
Table 3.5. Typical density ranges of common cereals
Cereal Type
Wheat
Hard
Soft
Durum
Oats
Barley
Rye
Rice (dehulled)
Sorghum
Maize
Density (gcm-3)
1.280-1.478
1.360-1.478
1.280-1.430
1.450-1.480
1.10-1.20
1.28 (mean)
1.34 (mean)
1.35-1.39
1.23-1.33
1.25 (mean)
Bulk testing methods of density determination, such as hectoliter weight, commonly used as
indicators of commercial wheat quality in the milling industry, although fast and cheap, can give only
limited information in a single average apparent density for the sample being measured and cannot
give any information on the distribution of density values within a wheat sample. Bulk testing
methods will also depend on factors other than the density of the wheat, such as the degree of packing
of the grains, the size and shape of the crease, and surface properties of the bran. Similarly, liquid
displacement methods will be prone to errors because of trapped air, such as air spaces between the
grains, within the crease, or in the brush hairs. To obtain reliable information about the density of
endosperm and the distribution of density values, measurements must be performed on a large number
of single pieces of undamaged endosperm.
Drying and storage
Moisture content in the cereal grain plays a vital role in the chain of handling and storage.
Germination, microbial growth, insect infestation, deterioration of color, development of off-flavor,
and lowering of nutritive value are some common quality factors associated with storage of highmoisture grain that render the commodity unfit for human consumption. Thus, removal of moisture
becomes a crucial step to provide extended storage life, facility of handling, retention, or enhancement
of quality, and new products for further processing. Drying of grain can be done by the natural action
of the sun. When the use of sun energy is not feasible or not satisfactory for various reasons artificial
drying is an option. It is a very energy-intensive process; thus, the efficiency of a drying operation in
terms of energy and time has economic consequences for commercial viability. The final moisture
content of the product to be achieved is largely decided by the storage environment and its storability
or set tolerance limits on the quality attributes. This, in turn, dictates the selection of a drying system,
drying time, and the range of operating parameter values. Acceptable moisture content for storage
Mold growth and insect infestation are the main causes of grain spoilage during storage. Both grain
temperature and moisture are important in helping to maintain good quality grain. Table 3.6 gives
typical recommended moisture contents for grain storage.
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Table 3.6. Recommended storage moisture content for grain (%wb)
Grain quality
Grain quality can be defined in terms of physical quality characteristics, sanitary quality
characteristics, and intrinsic quality characteristics. The drying process affects each of these quality
indicators. Damage from overheating lowers the quality of grain for commercial milling uses In
severe cases, overheating may cause scorching and discoloration, which lowers market grade. The
effects of overheating on kernel discoloration (browning) are a combination of the drying air
temperature and the time of grain kernel exposure to that temperature. Physical damage can result
from too-rapid drying (or too-rapid cooling) of grain, which causes stress cracks in the kernels. Stress
cracks are failures of the starchy endosperm of the kernel, resulting in a condition whereby only the
seed coat maintains the physical integrity of the kernel. The percentage of stress cracks developed
during drying increases as the rate of drying rate (expressed in percentage points per hour) increases.
Recent research has focused on methods to assess the breakage susceptibility of grain in the
marketplace. After a sample of grain is placed in a chamber that houses a spinning impeller, the
impeller spins for a set period. The grain is removed from the chamber, and the percentage of broken
kernels is the leakage. Broken kernels are defined as those that pass through a 4.75-mm (12/64-in.)
round-hole screen. For shelled corn, the breakage susceptibility increases dramatically as the grain
dries below 12%. More important to the food and feed industry is the development of molds and their
toxic metabolites. Although not directly associated with the drying process, the development of mold
species and the risk of toxin development relate to the moisture content of the grain and the time spent
at that moisture content. This relationship between spoilage and temperature, moisture, and time has
been referred to as the allowable storage time.
Intrinsic quality characteristics
The drying process affects the value of the grain for seed, animal feed, or milling or other processing.
High kernel temperatures during drying reduces protein content in feed grains, the yield of flour and
starch during milling, the yield and quality of oil pressed from oilseed, and the percentage of
germinating kernels in grain used for seed. From a drying perspective, the impact of drying on
intrinsic quality characteristics can be limited by using air temperatures less than the maximum drying
air temperature for a specific grain and use.
154
Drying systems
There are many different types of systems used for drying grain. The discussion below pertains
primarily to equipment in common use in the United States for drying grain.
Fans
Fans move the drying air through a bed of grain. The fan, forcing air against the grain static pressure,
determines the amount of air that moves through the grain during drying. The amount of air
determines the drying time and cooling time, affects the energy efficiency of the dryer, and influences
the grain quality. Two fan types used for forcing the drying air through a mass of grain are axial-flow
fans and centrifugal-flow fans. Fans are selected for their airflow and static pressure performance
characteristics. Each fan has its own performance characteristics, typically presented in a fan curve or
fan table as airflow (m3/ mm, or cfm) versus static pressure (cm, or inches of water column). Table 4.9
presents sample fan tables that represent a range of 10-hp axial and centrifugal fans. Axial-flow fans
are commonly used for both drying and storage aeration because they cost less for the same delivered
airflow. However, they are best suited for static pressures of less than 10 cm (4 in.) of water column.
Axial-flow fans are also noisier than centrifugal fans. Centrifugal-flow fans are best suited for static
pressures greater than 10 cm (4 in.) of water column. The advantages of centrifugal fans include their
low-noise characteristics. While the airflow produced by any fan will decrease as the static pressure
increases (shown in Table 4.9), the grain static pressure response increases as airflow increases. The
point at which the grain static pressure response equals the fan static pressure for an amount of airflow
is the operating point for the fan. Airflow per unit of grain is a useful characteristic for evaluating a
fan, because it directly relates to the time required to dry or cool grain. Rated horsepower is not a
good way to compare fans; the horsepower required is determined not only by the airflow and by
static pressure, but also by the efficiency of the fan blade in moving air.
Low-Temperature Bin Dryers
Low-temperature drying means drying with natural air or air with its temperature increased by up to
5°C (100 F). Drying and storage occur in the same bin-thus the name in-bin drying. The bin has a
fully perforated floor, high-capacity fan or fans, grain unloading equipment, and possibly a heater and
a grain spreader. Low-temperature drying bins can include stirring equipment for controlling the
uniformity of the final grain moisture content and increasing airflow rate. Disadvantages include
increased investment and maintenance cost and about 0.5 m (1.5 ft) of storage depth lost to the stirring
equipment drive mechanism. Stirring does not significantly increase grain damage. Fines can be
shifted to the drying floor, where they will reduce drying airflow. Adequate airflow is the key to
successful low-temperature drying. Airflow rates are typically 1 -3 m3/mint (0.9-2.7 cfm/bu).
Increased airflow rates require larger fans with more power and higher initial and operating costs and
can be more reliable in completing the drying required before excessive grain spoilage occurs. Adding
heat (up to 5°C, 10°F) does not necessarily reduce the air needed for safe drying and may cause over
drying. Increasing the airflow is a better means to dry grain faster and reduce the chance of spoilage.
If heat is used with low-temperature drying, common sources are electricity, LP gas, and the sun.
Table 3.7. Static pressure difference across fan types
155
Low-temperature drying systems are considered low-initial-investment and low-drying-capacity
systems. Low energy use and excellent grain quality can be expected. These systems are best for
grains with low moisture contents at harvest and for drier geographical areas with low relative humidy
during the fall. The maximum moisture content for the single-fill low-temperature drying method with
the recommended airflow is 22 % for corn, 18 % for sunflower, 15 % for flaxseed, and 17 % for small
grains.
High-temperature bin-batch dryers
High-temperature bin-batch dryers dry batches of grain with heated air (Fig. 4.14.). Two types of binbatch dryers are the on-floor and hatch dryers. Airflows of 10 25 m3/mint (9 23 cfm/bu) are typical,
with drying temperatures of 35-60° C (100—140°F). Drying and storage occur in separate bins. The
drying bin has a perforated floor, drying fan, heater, and grain-unloading equipment. Batch drying
bins may also have a grain spreader or grain-stirring equipment. One drying bin can dry grain for one
or more storage bins. High-temperature bin-batch dryers have moderate initial investment and
moderate energy use. Representative drying capacities are presented in Table 4.8. Good to excellent
grain quality can be expected, since the amount of over drying is limited, and the drying rate is
moderate. These systems will dry one or two batches per day, with typical seasonal volumes up to 500
t (20,000 bu).
Fig. 4.14. High temperature bin-batch dryers
Compared with other drying systems, bin-hatch dryers often cost less per unit of drying capacity but
require more labor. Someone usually needs to supervise the transfer of each batch to storage and fills
in the next batch and level grain if spreaders do not operate properly.
On-floor bin-batch dryer
An on-floor bin-batch dryer dries a layer of grain on a perforated floor (Fig. 4.4). Batch drying depth
and drying air temperature are usually limited, so the moisture content of the dried batch varies by
less than about five percentage points (e.g., 16-11%) between top and bottom. Recommended grain
depth for drying is 0.8-1.2 m (2.5-4.0 It) without stirring. With stirring equipment, grain depths for
drying can be up to 3 m (10 ft). Moving the dried batch to storage mixes the moist top grain with the
drier bottom grain for safer storage. As grain depth increases, drying capacity decreases, and it is
more difficult to manage the drying process.
Roof bin-batch dryer
Roof bin-batch dryers dry a layer of grain about 0.8 m (2.5 ft) deep on a coned perforated floor under
the roof (Fig. 4.4). Wet grain is loaded onto the coned perforated floor for drying. The space between
the grain and the drying floor is a hot air plenum. Heat from the cooling grain adds heat to the drying
156
air. Hot dried grain drops onto a totally or partially perforated floor for cooling or storage. It is cooled
with a separate fan, while the drying chamber is refilled with wet grain, and drying starts again
Continuous-flow bin dryers
A continuous-flow bin dryer is usually a bin with a perforated drying floor, fan, heater, grain spreader,
grain-unloading equipment, and an auger to transfer grain to storage (Fig. 15 and 4.16). These dryers
unload hot, dried grain semi continuously from the bottom of the drying bin to storage bins equipped
for cooling. The grain flow is automatically controlled to limit over drying.
Table 3.8. Shows bin diameter, airflow and drying capacity
Fig. 15. Continuous-flow bin dryers
Optimum grain-drying depths are 1-2 m (3.3-6.6 ft). Airflows of 10-25 m3/mint (9-22 cfm/bu) are
typical, with drying temperatures less than 80°C (176° F). Grain recirculation or stirring equipment is
used only when the last batch of grain is dried and stored in the drying bin. If grain is stored in the
drying bin, a perforated wall liner or evenly spaced perforated tubes are needed to minimize
condensation. Continuous-flow bin dryers have moderate initial investment and moderate energy use.
Good grain quality can be expected, because the amount of over- drying is limited, and the drying rate
is moderate. These systems are used for seasonal volumes of up to 750 t (30,000 bu).
High-temperature column dryers
High-temperature grain dryers are characterized by multiple vertical columns that hold the grain while
the air is forced horizontally through the grain. Column thickness for these dryers varies from 30 to 40
157
cm (12—16 in.). The wider columns provide improved energy efficiency, but at the sacrifice of
greater variation among kernel moisture contents and somewhat lower drying capacity. Hightemperature dryer capacities are quoted for ideal drying conditions. These conditions rarely occur on
the farm, with realistic capacities being 80% of the advertised value. Design airflow varies from 80 to
100 m3/mint (70—90 cfm/bu), with drying air temperatures up to 100°C (2l2°F). High-temperature
column dryers require a moderate to high initial investment and high-energy use. Grain quality
problems due to brittle kernels result from the high drying rate and the rapid cooling typical of these
dryers. Seasonal volumes up to 1,500 t (60,000 bu) are normal for batch units, with continuous units
used for seasonal volumes above 3,750 t (150,000 bu).
Fig. 4.16. High-temperature grain dryer
Manual batch column dryers
These dryers are typically for drying small volumes of grain per year. An advantage of manual batch
dryers is portability. They can be used in several locations, including in-field drying. Only the dryer,
LP gas tank, and perhaps one conveyer need to be moved. Disadvantages include more labor and
supervision for loading, drying, and unloading each batch. The additional grain handling inherent in
these units can lead to additional grain damage.
Automatic batch dryers
Automatic batch dryers are column dryers that are mostly permanent installations (Fig. 4.17). Loading
and unloading of a batch dryer are automatically controlled to control grain moisture content. These
dryers can be used to dry and cool grain, or they can transfer hot grain to storage for delayed cooling.
The use of delayed cooling is strongly recommended for shelled corn.
Fig 4.17. Schematic diagram of Automatic batch dryers
158
Continuous-cross flow column dryers
Continuous-cross flow dryers (Fig. 4.10) are high-capacity dryers for the investment but can be
operated such a way that high energy use and low grain quality result. These dryers are used most
often for shelled corn but can be used to dry other grains, if lower temperature limits can be set. These
dryers can be used to dry and cool grain, or they can transfer hot grain to storage for delayed cooling.
The use of delayed cooling is strongly recommended for shelled corn.
Concurrent-flow dryers
In a concurrent-flow dryer, the air and the grain both flow downward through the dryer (Fig. 4.18).
The hottest air encounters the moist grain. The air is cooled rapidly, due to the high rate of moisture
evaporation, allowing the use of drying-air temperatures as high as 50-250°C (300-500°F).
Concurrent-flow dryers are considered high-investment and high-drying- capacity equipment. The
advantage of this type of dryer is that all the grain kernels receive the same drying treatment, thus
avoiding no uniformity in grain temperature and moisture content, which is inherent in the design of
continuous-cross flow dryers. Seasonal volumes greater than 1,250 t (50,000 bu) are typical.
Other dryers
Several types of dryers other than those included in the preceding discussion are in use or have been
researched.
Fig 4.18. Continuous-cross flow dryers
Fluidized bed dryers, spouted bed dryers, rotary drum dryers, and even microwave dryers have been
investigated for drying grain. None of these types is currently in active use for drying cereal grains in
the major grain-producing regions of the United States.
Grain Cooling
Grain dried in any heated air dryer must be cooled (Figure 4.20). It can be rapidly cooled immediately
after drying, or delayed-cooling methods can be used to reduce fuel costs, increase dryer throughput,
and reduce stress cracks and breakage susceptibility. With delayed cooling, hot grain is usually
transferred from a high-temperature dryer to a separate bin to be cooled. In-bin cooling, dryeration,
and combination high- and low- temperature drying are the three most often used delayed-cooling
methods. Delayed-cooling effectiveness increases as drying-air temperature increases. The minimum
drying-air temperature to consider delayed cooling is 50°C (120° F).
In-bin cooling
In-bin (or in-storage) cooling is the simplest delayed cooling method and is suitable with any type of
high-temperature dryer. Compared with rapid in-dryer cooling, in-bin cooling can reduce fuel costs at
least 10% and increase the capacity of a high-temperature dryer by 10-20%.
159
Fig 4.19. Continuous cross flow column dryer
The general operating procedure is to stop high-temperature drying when the grain moisture is about
1% above the desired final moisture content. The hot, dried grain is then transferred to storage and
cooled continuously to remove additional moisture. About 0.1 to 0.15 percentages of points are
removed for each 5°C (10°F) reduction in grain temperature during the process. After cooling, grain is
usually stored in the cooling bin.The minimum airflow (m3/min; cfm) for cooling is 12 times the
desired cooling rate (t/hr; bu/hr). For example, a 5-t/hr (200-bu/hr) drying capacity requires fans to
cool at least 5 t/hr (200 bu/hr) when the bin is full. The minimum fan size is 60 m3/min (2,400 cfm) at
the maximum grain depth. Bins with fully perforated floors provide the best air distribution for in-bin
cooling. Partly perforated floors or ducts are adaptable, but air movement through the grain will be
less uniform.
Fig. 4.20. Grain cooler
160
Dryeration
Dryeration is an energy-efficient method of delayed cooling and drying completion. Compared with
immediate, rapid cooling in the dryer, dryeration reduces fuel use 15-30 %, increases drying capacity
up to 50 %, and results in fewer stress cracks, less brittleness, and improved color (bloom) and
millability (Figure 4.21). With dryeration, hot grain is moved to the cooling bin immediately after
drying. Cooling is delayed at least 4 hr for steeping or tempering, while the moisture content equalizes
in the kernel. As the grain cools, the air warms to the grain temperature and absorbs moisture from the
grain. This warming and drying happens over a short distance in the grain, forming a cooling front
that gradually moves through the bin. Air moving through warm grain ahead of the cooling front does
not significantly change the grain’s temperature or moisture content, so warm grain continues to
temper, though air is moving through it. Dryeration results in fewer stress cracks during cooling and
in more moisture removal. Drying in a high-temperature dryer can be stopped when grain moisture
content is 2-3 percentage points higher than the desired final moisture content. The cooling and drying
effect of dryeration reduces grain moisture content about 0.2-0.25 percentage points for each 5°C
(10°F) reduction in grain temperature during cooling. After the grain is cooled in the dryeration bin, it
should be transferred to storage. Airflow of 0.6 1.2 m3/mint (0.5 1.0 cfm/bu) should be provided when
the bin is full. The higher the airflow, the faster the grain cools: 0.6 m3/mint (0.5 cfm/bu) cools hot
grain in about 24 hr, and 1.2 m3/mint (1.0 cfm/bu) cools it in about 12 hr. More management is
required for dryeration, but the extra energy savings, dryer capacity, and grain quality can more than
offset the disadvantages. Improved grain quality, especially by corn, is often overlooked but is
becoming increasingly important in grain marketing.
Fig 4.21. Grain cooling in bins (dryeration)
Milling Cereals
All the cereal grains are plant seeds and contain a large centrally located starchy endosperm, which is
also rich in protein. Almost all the cereal grains are covered with protective outer layers such as husk
and bran. The germ or embryo is located near the bottom of the seed. For general food uses we
remove hulls which are largely cellulose and indigestible to human being, the colored bran and germ
which contain most of the oil. Since the oil is attacked by enzymes and produce rancid condition in
grain, the germ is removed. For various foods, starchy and proteinaceous endosperm is used.
Sometimes the ‘B’ vitamins and minerals are added to ground meal, which is known as enrichment.
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Grinding of cereals may be broadly classified into plain grinding and selective grinding. In the first
case grains are milled to a free flowing meal consisting of sufficiently uniform particle size, whereas
in the second process the grinding operation is carried out in various stages depending upon the
differences in structural and mechanical properties of components of grain. Hardness of seed effects
the power requirements of grinding.
Average size of particle in a ground product
For the measurement of the particle size in the range between 76 mm to 38 µm (micrometer), standard
screens are used. These screens are known as ‘testing sieves’ and are made of woven wire screens.
The mesh and dimensions of testing sieves are carefully standardized. The openings of these test
sieves are square. In 1910 a series of test sieves called Tylar sieves were originated in the USA which
were adopted by the US Bureau of Standards. The opening size of the Sieves is based on the 200mesh sieve. This sieve has 200 openings in one inch. The nest sieve opening is larger by 2 or 1.41
times than the previous screen. Intermediate sieves with opening ratios of 1.189 are also available.
These intermediate screens are not commonly used. For analysis of ground products, a set of standard
screen is arranged serially in a stack. In the bottom, a pan is placed and then on it smallest mesh size
sieve is placed. On the top of the mesh, the next larger one is placed and thus serially the stack is
arranged. The size of openings of standards screens are given in Table 3.9. Food grains are composed
of cellulose, fiber, starch, fat etc. These constituents affect the size, shape, and distribution of the
particles in milling operation. Milling of grains is usually done by abrasive or impact type of mills.
Performance of a mill is characterized by the capacity, power requirement per unit of material
reduced, size and shape of the product before and after reduction and the range in size and shape of
the product. The most common method of classification of comminuted product is screening of the
ground material through set of sieves, which is also called as “screen analysis.”
Table 3.9. Test sieves and their respective sizes
162
Screen analysis
For determination of average particle size in ground food grains, a set of Indian Standard Screens is
arranged serially in a stack. For food grain flour analysis, a set of IS Sieves No. 100,70,50,40,30,20
and 15 with pan and cover is taken. A sample of 250 g of ground product is dried in an oven to a
constant weight. The dried sample is placed in the topmost sieve and the set is placed on a sieveshaking machine and shaken for 5 minutes.
Cereal milling machines
Crushers
This type of reducing machines squeeze or press the material until it breaks. Crushers are mostly used
to break large pieces of solid materials into small lumps. Crushers are used in industrial operations,
like mines etc. Use of crushers in agricultural operations is limited.
Serrated or toothed-roll crushers: In such crushers, the rolls are serrated as per need. Toothed-roll
crushers (Fig. 4.22) are much more versatile than smooth-roll crushers are. The best example of such
type is the break and reduction rolls of a wheat flour milling plant. Disintegrators are the toothed-roll
crushers in which the corrugated rolls are rotating at different speeds. These machines tear the feed
apart. The size reduction in serrated-roll crushers is by compression, impact, and shear, and not by
compression alone, as in the case of smooth roll crushers. The serrated-roll crushers can also
accommodate larger particles than smooth-roll crushers can.
Fig. 4.22. Serrated or toothed-roll crusher
Grinders
The grinders are used to mill the grains into powder. The grinder comprises a variety of size-reduction
machines like attrition mills, hammer mills, impactors and rolling compression mills.
Attrition mills
In an attrition mill the grains are rubbed between the grooved flat faces of rotating circular disks.
These mills are also known as burr or plate mills. The axis of the roughened disks may be horizontal
or vertical (Fig. 4.23). In addition, mill one plate is stationary and fixed with the body of the mill,
while other one is rotating disk. The material is fed between the plates and is reduced by crushing and
shear. Mills with different patterns of grooves, corrugations on the plates perform a variety of
operations. In attrition mills the materials are slowly, fed overfeeding lowers the grinder’s
performance, also heat generation during milling increases. The disks of burr mills are usually 20 to
137 cm in diameter and are operated at 350 to 700 rpm. These mills are used for making whole grain
and dehusked gram flour, but their use in spices grinding is limited. Double runner disks type attrition
163
mills are also available. These are used for grinding of soft materials. In these mills both disks are
driven at high speed in opposite directions. Feed enters through an opening in the hub of one of the
disks; it passes outward through the narrow gap between the disks and discharges from the periphery.
The disk are operated between 1200 to 7000 rpm, hence the capacity of such mills is large.
Fig. 4.23. A vertical disk attrition mill
The type of plates and the gap between them controls the fineness of grinding in burr mills. The
spacing between the plates is adjustable and usually the arrangement is spring loaded to avoid damage
to plates in case of over loading or to overcome tile damage to plates by foreign material coming
along with the feed. The salient features of a burr mill are its lower initial cost and lower power
requirements. But foreign matter may cause damage/breakage, and operation without feed may result
in burr wear. Such mills are in large use for most of the cereal grains including tef throughout
Ethiopia.
Hammer mills
Hammer mills are used for various types of size reduction jobs. These mills contain a high-speed
rotor, rotating inside a cylindrical casing. The shaft is usually kept horizontal. Materials are fed into
the mill from the top of the casing and is broken by the rotating hammers and fall out through a screen
at the bottom. The material or feed is broken by fixed or swinging hammers, which are pinned to a
rotor. The hammers are rotated between 1500 and 4000 rpm, strike, and grind the material until it
becomes small enough to pass through the bottom screen (Fig. 4.24). Fineness of grinding is
controlled by the screen size used.
Fig. 4.24. Hammer mill
164
Hammers are either rigidly fixed to the shaft or swinging. In case of swinging hammer mill there is
less chances of damage of hammer if some unbreakable solid material comes to milling chamber
along with feed. There are several designs of striking edge of the hammers. Hammer mill can grind
almost anything—like tough fibrous solids, steel chips, food grains, sticky clay, and hard rock. The
hammer mill is assumed to reduce size by impact. The kinetic energy of the rotating hammers is used
to disintegrate the feed. Most of the size reduction is achieved by impact of hammers, though some
amount of shear also takes place between the feed and screen and other mill parts. The salient features
of hammer mill are their simplicity and versatility in design and work, freedom from damage during
empty operation and less chances of damage of mill due to foreign objects. The worn hammer does
not significantly reduce the efficiency of mill, but the main disadvantage of the mill is its high power
requirements. The capacity and power requirements of hammer will depend on the nature of feed to
be ground. Commercial mills reduce solids between 60 to 240 kg(kWhr)-1 of energy consumption.
Hammer mills are used for poultry feed grinding, spices grinding. It was also found suitable for
grinding of wet sorghum and millets and for potato, tapioca, banana and similar flour making.
Ball mills
The ball mill is a cylindrical or conical shell slowly rotating about a horizontal axis. Half of its
volume is filled with solid grinding balls (Fig. 4.25). The shell is usually made of steel lined with high
carbon steel plate, porcelain or silica rock. For medium and fine reduction of abrasive materials ball
mills are used. In a ball mill size reduction is achieved by impact of the balls when they drop from
near the top of the shell. The balls are carried up the side of the shell nearly to the top. By gravity the
balls drop on the feed underneath. The energy consumed in lifting the balls is utilized for grinding job.
Fig. 4.25. Ball mill
When the ball mill is rotated, the balls are carried by the mill wall nearly to the top where they are
released by gravitational pull and drop to the bottom and picked up again. Centrifugal force keeps the
ball in contact with the mill wall. Most of the grinding is done by the impact of balls. Due to
centrifugal force, if the speed of rotation of mill is faster, the balls are carried to more distance. In
case of too high speed, balls stick to mill wall and are not released. This is a stage of centrifuging. The
rotational speed at which centrifuging occurs is known as critical speed. At this speed as the balls are
released from the top, no impact occurs hence little or no grinding results. Therefore, the operating
speeds must be kept less than the critical speed. The speed at which the outermost ball released from
the mill wall depends on the interaction of gravitational and centrifugal forces. The critical speed can
be determined by the following equation
nc =
1
2π
g
R−r
…4.1 where, nc = critical speed, revolution.s‐1 165
g = acceleration due to gravity, 9.80 ms‐2 R = radius of the mill, m r = radius of the ball, m The rotational speeds of the ball mills are kept at 65 to 80% of the critical speed, with the lower
values for wet grinding in viscous suspension.
Milling of Pulses
Introduction
Pulses are good source of proteins. They are consumed in form of dehusked and split kernel. Milling
of pulses for the production of split grain is an age-old process and varies in milling procedures vary
widely from place to place. The recovery of split product is influenced by such factors as variety,
agronomic factors of pulse production, size of seed, maturity, and uniformity and it varies from 60 to
75% depending upon the type of pulses and techniques adopted by the millers. Improper conditioning
of pulses and machine parameters can cause lower yields reducing it by up to 10 to 20 %. Dehusking
is a process, which involves removal of the fibrous seed coat, and there is no standard process for
milling pulses; where various parameters involved are optimized. Use of oil mixing with pulses for
conditioning and the application varies from 150 to 500 gq-1 of grain. Similarly, addition of water also
varies from 4 to 20 kg per 100 kg of grain. For loosening of husk and its complete removal 3-8 passes
through emery rollers are given. This action causes breakage and powdering of kernel.
Structure of pulses
Pulses are dicot plants and there is much similarity in the structure of the seeds of various pulses.
However, they differ from each other in color, shape, size and seed coat thickness. The outermost
layer of the seed is the testa or seed coat. The endosperm in mature seed is in the form of a layer
surrounding the cotyledons or embryo. There are a few external structures like hilum, micropyle and
raphe. The hilum is an oval shaped scar in the middle where the seed is attached from the stalk. The
micropyle is a small opening in the seed coat beside the hilum. The raphe is in a ridge from beside
hilum and opposite to the micropyle. Inside the seed coat the seed is composed of embryonic
structure. The embryo consists of a radicle, a plumule or epicotyle and a hypocotyle which connects
the radicle and the plumule.
Chemical composition of pulses
Pulses contain 17 to 25% of protein by weight. The protein content of pulses is about double of the
cereals and more than meat, and egg. On the other hand pulses contain low level of lipids and fats.
They are good source of thiamin, niacin, calcium, and iron. In dry pulses very low amounts of
ascorbic acid is present, but when these are soaked in water, during their germination, ascorbic acids
are made available.
Pulses protein: Man and other monogastric animals get protein from pulses. The proteins of pulses
are mainly glocolin, some species of pulses may also contain albumin. The standard of proteins
depends on the composition of amino acids. The protein efficiency ratio of pulses is from 0.7 to 2.1,
which is less than egg and milk protein. When cooking the nature of pulses proteins improve. Pulses
contain more amount of lysine while sulfur-containing amino acids are in lower quantities. In many
developing countries, pulses meet much of the daily protein need. Since cereals have low levels of
lysine, when these are mixed with pulses the per value of diet improves. Proper quality of protein can
be obtained through cereal and pulses diet, which is easily digestible. It is a general belief that pulses
are comparatively hard to digest by monogastric animals. Various studies have shown that
digestibility of well cooked pulses go up to 90%. Pulses contain about 60% carbohydrate mainly
starch, which in general is well absorbed and utilized. The fat content is between 1 and 2 %.
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Pulse Milling Processes
Pulse milling constitutes two major steps: loosening of the husk, followed by removal of the loosened
husk in suitable milling machinery. The first step is commonly referred to as pre-milling treatment,
whereas the second is referred to as milling or dehulling. The first step of loosening the husk is
achieved either by a wet or dry method, thus dividing the process in to two categories. In the wet
method, the grains are soaked in water for a few hours, drained, left in heaps (usually overnight), and
very commonly dried in the sun. In the dry method, grains are mixed with a small amount of oil,
usually after scarification of the husk. This scarification of the husk is commonly called pitting and is
done to facilitate the oil penetration between the husk and the cotyledons. Oil-treated grains are
heaped overnight and then dried in the sun for 2-5 days, with intermittent water spraying and mixing.
In both of the pre-milling treatments, adherence of the husk to the cotyledon weakens and,
consequently, its removal becomes easy. The loosened seed coats of the pretreated pulses are removed
in the subsequent operation of milling. For this purpose different machines are used, depending on the
type of pulse and scale of operation. Pulse milling is practiced at different levels: home-scale, cottagescale, and large-scale, and machines such as pestle and mortar or hand-driven disk mills are used in
home-scale operation. In cottage-scale, a motorized plate mill, under-runner disk Sheller, horizontal
flourmill, or hullers are used for the milling; whereas emery-coated roller machines are used mainly in
large-scale operations. Dry pre-milling treatment is preferred for larger-scale operation, although it is
time-consuming and laborious. Generally wet-processing methods are practiced in small-scale and in
rural sectors for producing small quantities of split pulse to meet the household requirements. Largescale pulse mills always prefer dry-processing methods. Pulses can be grouped in two categories as
“easy-to-mill” and “difficult-to-mill” depending on their milling characteristics. Because the seed coat
(husk) of some pulses such as red gram, green gram, black gram, and beans is tightly adhered to the
cotyledons through a layer of gum it is difficult remove. Pulses like chickpea, peas, or lentils have
husks loosely enveloping the cotyledons, hence is easily separated. Accordingly, the milling processes
of the two categories are slightly different from each other. Generally easy-to-mill pulses can be
processed in small-scale mills, whereas all difficult-to-mill pulses need to be processed in large-scale
pulse mills using dry pre-milling treatments. A product obtained by dry method is said to cook better
while that produced by wet method tastes better but takes longer time to cook. In either way, the main
common unit operations performed in milling of different pulses are outlined as follows.
Important unit operations of pulse milling
Cleaning/grading of raw grains
Pulses must be cleaned during the process, because they may be delivered containing up to 20%
impurities. Foreign materials include pod walls, broken branches, soil, cereals, oilseeds, weed seeds,
diseased and deformed seeds, and stones. Initial cleaning of lentils takes place on scalpers and air
screens. Raw material is cleaned by removing dust, dirt, foreign material, off-sized, immature, and
infested grains. The cleaned grain is graded into uniform sizes. Air draft and rotary screens with round
holes are used for cleaning. In rotary screens, however, the grain does not have equal opportunity to
meet the sieve before reaching the end of the separation zone, which leads to improper grading. After
the lentils are conditioned with water and tempered, the seeds are graded on round-hole rotary
screens. The graded seeds are then dehulled, and the mixture of whole and split lentils, hulls, broken
seed, and fines are passed through an inclined gravity separator to remove broken seed and fine
particles. Whole seeds are screened from splits and are returned to the dehuller. The splits are fed into
a horizontal gravity separator to separate dehulled from hulled splits. Destoners are also used to
separate mud and stones. The cleaned grains are then graded as per their size mostly by a reel grader.
The presence of impurities lower the quality of the product and the impurities may also damage the
milling machines.
Conditioning
Food legumes are consumed mostly in the form of dehusked and split grains. A layer of gum between
cotyledons or kernel and outer husk is present in most of the pulses. This gum layer may be thin or
thick which in turn governs the degree of adherence of the seed coat to the cotyledons. The nature of
gums influences the adherence of husk to kernel while the amount of gum affects the duration and
167
severity of the conditioning process. The main objective of the conditioning is to loosen the husk to
facilitate its separation from the kernel, thus reducing the milling losses. The conditioning process is
done by various methods. There is no standard method. Conditioning of grains can be achieved by
water treatment, hydrothermal treatment, use of salts and chemicals, and use of heat alone.
Insufficient conditioning results in incomplete loosening of husk, therefore, greater abrasive/scouring
forces are necessary for complete removal of the husk. This causes higher milling losses in the form
of brokens and powder with lower recovery of dhal.
Dehusking and Splitting
The conditioned grains are subjected to abrasive/scouring forces for removal of husk and for splitting
of cotyledons into two equal halves. Dehusking and splitting is the most important and major unit
operation of any pulse milling process. Dehusking of pulses generally carried in an abrasive roller
mill. In some pulse milling plants, vertical stone is also used to dehusk and split the grains. For
splitting of the dehusked and moistened grains, vertical disk burr mill is used or the grains are allowed
to fall on a hard or cemented surface from sufficient height. Due to impact with hard surface, the
dehusked grains are split.
Polishing of split kernel
This is done to impart desirable shine and lusture to the product. During this process, a pre-desired
quantity of edible oil and water is mixed with split grain (kik) by passing them through a screw
conveyor. The presence of oil and water imparts desirable color and shine to milled pulses.
Grading of milled product
Separation of split kernel is carried mainly as per their size and soundness. The separation is usually
achieved by rotating reel graders, in which separate compartments have different opening sizes of
screens. Various sizes of split fall through the openings of these screens. Graded products are bagged
separately as per their grades. In general the two processes for milling of pulses are indicated in the
flowcharts. However, variations exist in pre-milling treatments and milling machines used for
different pulses as each pulse has a specific characteristic end use.
Table 3.10. Milling recoveries of pigeon-pea
Milling fractions
(%)
Full split
Broken
Powder
Husk
Milling method
Commercial
Manual (small- scale)
Range
Average
Range
Average
60 – 95
70.0
50 – 80
60.2
2 – 10
4.5
5 – 20
10.8
9 – 15
12.8
7 – 22
13.0
5 – 20
12.7
10 – 25
15.5
Seed characteristics that affect milling
Several seed characteristics affect the dehulling efficiency, for example, size and shape of the grains,
husk content, and its thickness, adherence of the husk to the cotyledons, and moisture content.
Interaction of pre-milling treatments and seed characteristics play an important role in determining the
dehulling quality. Selection of pre-milling treatment also depends on the seed characteristics of the
grain.
Nature of seed coat
In pulses, a tough, single seed coat tightly envelopes the cotyledons. In some pulses, such as cowpea,
green gram, and lentil, the seed coat is thin, forming about 5-10% of the grains, whereas in other
pulses, such as chickpea and pigeon pea, it is thicker and constitute about 12-15% of the pulse. As
shown in Table 4.11, mean seed coat content ranges between 4.9 and 14.4% for different pulses,
indicating a large variability. Variation occurs even within several varieties of the same pulse. This
168
would significantly affect the expected yields of dehulled grains. The theoretical yields of dehulled
grain are determined by subtracting the seed coat content from the total seed mass.
Table 3.11. Variability in Seed Coat Content of Different Pulses
Number of
Range
Mean
Pulse
genotypes
(%)
(%)
Chickpea (brown)
21
9.7-17.3
14.2
Chickpea (white)
19
3.7-7.0
4.9
Pigeon pea
22
12.6-17.2
14.4
Green gram
24
7.4-11.4
8.8
Black gram
5
8.9-11.6
10.4
Lentil
6
7.0-8.0
7.2
Cowpea
3
9.0-11.5
10.5
Kidney beans
5
9.0-11.2
9.7
Horse gram
2
11.2-13.4
12.5
Physical characteristics of grains
Dehulling characteristics are governed, to some extent, by the seed morphology, which varies
immensely among legumes. Differences in the cell arrangements of the pulses seed coats influence
their dehulling characteristics. The seed coat in cowpea consists of a highly organized palisade cell
structure.
Studies showed that cowpea varieties with thick, smooth seed coats (highly organized palisade cells)
dehulled easier than with rough seed coats. In white-husked chickpeas, the outermost layer
(epidermis) develops into a uniseriate palisade layer without thickening of the cell wall, whereas in
brown-husked chickpeas, it develops into a multiseriate palisade layer that later becomes thick-walled
sclereids, heavily stainable with toluidine blue. This would probably explain the easier-dehulling
properties of brown chickpea varieties than those of the white-husked varieties.
Seed size is one of the factors affecting the dehulling process in pulses. A varietal character is
influenced by the growing season and location. Uniformity in size is also important for efficient
dehulling. Dehulling efficiency is negatively correlated with seed size in green gram and cowpea. The
choice of the device for dehulling the pulse also depends on the size of the pulse. If the dehulling
equipment, such as roller machine or stone grinder, is not properly set, large seeds are most likely to
break resulting in significant losses during dehulling. Studies also suggested that uniform and
medium-sized pigeon pea seed would improve the efficiency of dehulling. Very small seeds are more
difficult to dehull because they split even before husk removal and, hence, require several recycling
steps and, therefore, are not generally preferred by millers. The efficiency of dehulling and splitting of
lentil is favored by large seed size, thin testa, a short storage period and the correct wetting and drying
practices.
Similar to seed size, seed shape is a varietal characteristic in pulses. This characteristic is generally
not affected by the growing environment. Pulses exist in various shapes such as spherical-shaped pea
and pigeon pea, cylindrical-shaped green gram and black gram, pyramidal-shaped chickpea, flat ovalshaped field bean and horse gram and kidney-shaped beans. This property plays a vital role in the
selection of dehulling devices.
169
The hardness of seeds is another important grain property affecting the milling quality. Kernels of
some pulses such as green gram and cowpea are soft, whereas those of pigeon pea and kidney beans
are hard at normal moisture levels. Chickpea and black ram kernels have medium hardness. Although
the magnitude of correlations was low, grain hardness, has been reported to be negatively correlated
with the yield of dehulled splits, which implies that hard grain genotypes of pigeon pea would
produce lower yield. Variability in dehulling efficiency or yield of dehulled grain was significantly
affected by hardness of the grain and resistance to splitting in individual cotyledons. In addition,
several environmental factors may influence the yield of dehulled splits from pulses. Variations in
milling characteristics of pigeon pea, as influenced by variety and agro-climatic conditions, have been
reported. Location and maturation of pigeon pea, which influence seed size, shape, and grain
hardness, would directly affect the dhal yield in small-and large-scale-processing operations. Pigeon
peas grown on light soils have better dehulling and cooking qualities. A few millers also have
preferences for seed color, favoring white pigeon pea for their yield is better when compared with
other pigeon peas, and ability to splits with a smaller degree of dehusking, but less visible white spots
on leftover husk, can be sold in the market at a higher price than that obtained from colored seeds.
Effect of Varietal Differences on Dehulling Quality
A large variability has been reported in the dehulling quality of green gram, cowpea, chickpea, and
pigeon pea cultivars, as determined by the tangential abrasive dehulling device (3, 49). Among whitehusked (kabuli) varieties of chickpea, the yield of dehulled grains varied from 84 to 90%, whereas the
yield ranged from 73 to 83% among brown-husked (desi) varieties of chickpea (Table 3.12). From the
results of the studies in Table 3, it is apparent that a large variability exists in the dehulling quality of
different pulses and even among different varieties of the same pulse. However, such variability does
not appear to have received much attention when breeding for high-yielding varieties, although
dehulling quality of pigeon pea has been the subject of a few studies in the past. Pigeon pea varieties
generally exhibit fewer variations in dehulling characteristics than cowpea varieties. The dehulling
quality of the green gram cultivars is generally poor, because of their ease of splitting and long
dehulling time. These workers suggested that resistance to seed splitting during dehulling and a
loosely bound state of the seed coat to the cotyledons were the major seed quality requirements for a
good dehulling property of these legumes. Variations in the degree of dehusking obtained in this study
are possibly the result of varying extents of loosening-of husk from the cotyledons after pre-milling
treatments. These workers reported a wide range in the degree of dehusking (67-100%) of pigeon pea
varieties. Furthermore; dehulling property was independent of seed size and husk content, but was
greatly influenced by other varietal characteristics, such as quantity of gum between the husk and
cotyledon, extent of husk adherence, and moisture content of the grain at the time of dehulling. In a
subsequent study,
Table 3.12. Variability in Dehusked Splits of Different Pulses
Pulses
No. of
cultivars
Cowpea
Chickpea (brown-husked)
Chickpea (white-husked)
Pigeon pea
Green gram
Black gram
6
18
6
18
12
5
170
Splits yield (%)
Range
Mean
60-78
73-83
84-90
72-81
64-73
65-76
69.0
78.0
87.0
76.5
68.5
70.5
Milling characteristics of pulses
Pigeon Pea
This pulse poses the greatest difficulty in milling because the husk adheres tightly to the cotyledons.
Generally, only the dry method is followed. Cleaned and size-graded grains are pitted in smooth roller
machines, smeared with varying amounts (0.2-0.5%) of oil (any edible oil), tempered for about 12-24
hours, sun-dried for 1-3 days, followed by spraying with water (2-6%), thoroughly mixed, heaped
overnight, and then passed through the rollers for dehusking. This type of operation is repeated three
or four times. After each dehusking operation, the husk, powder, and brokens are separated from
dehusked split pulse. Dehusked splits obtained in this operation are considered as ‘second grade’
because their edges are not sharp and are usually rounded-off by scouring. The mixture of dehusked
and unhusked grains obtained during processing is again mixed with water, as described earlier,
equilibrated, and sun-dried. The sun-dried grains are either passed through the roller machine or split
in a horizontal or vertical grinder or by using an impact-type machine. The dehusked splits thus
obtained are considered as a “first grade,” because they would not have any chipped edges and would
have a better consumer appeal. Quite often, both first- and second-grade dehusked splits are mixed
and marketed. The yield varies from 70 to 75% depending on the variety and the method followed. In
large-scale mills, sun drying is being replaced gradually with batch-type bin driers, because of which
work can proceed throughout the year.
Chickpea
The chickpea is comparatively easy to mill. The cleaned and size-graded grains are pitted in smooth
rollers at low peripheral speed. After pitting, the grains are mixed with about 5-10% water in a screwconveyer-type mixer and heaped for a few hours to allow the water to seep in. The wetted grains are
sun-dried for 1 or 2 days. The dried pulse is then passed through either a horizontal or vertical stoneemery grinder, where dehusking and splitting takes place simultaneously. The dehusked splits are
separated from the husk and brokens with an appropriate aspirator and sifter; the remaining unhusked
grains are dehulled by repeating the foregoing operation until all the grains are dehulled.
Peas and lentil
The milling of these pulses is easy as found for chickpea. General practice involves initial scouring,
application of water, heaping, and sun-drying, followed by dehusking splitting, aspiration of husk,
separation of brokens and splits, and finally, polishing.
Pulse processing machines
Cleaning and size-grading systems
Pulses need to be cleaned of dust, dirt, immature grains, and other extraneous materials. They have to
be graded according to size. These operations are carried out by two types of machines: rotary- or
reel-type sieve-cleaners, and reciprocating sieve cleaners. The flat, reciprocating sieve-cleaners are
extensively used both by large- and small-scale-milling units. However, this type is gradually being
replaced by rotary-type cleaners in large mills. The rotary-type screen cleaner consists mainly of four
compartments of screens fitted on a shaft. The machine operates at low speed of 18 to 30 rpm on a
sloppy platform for a better performance. The body of the machine is generally constructed of wood
or mild steel. Advantages of this type of cleaners are lower dust and noise pollution and lowmaintenance cost. The reciprocating-type cleaner consists of two or three compartments of differentsized screens (depending on the type of pulse being milled) and a suction arrangement to remove dust
and other light particles. Normally pulses are graded into two or three different sizes. Screens would
usually be inclined at an angle of about 5 degrees to the horizontal, with amplitude of close to 15-20
mm; the speed is about 300-350 rpm. The size of the reciprocating cleaner varies from 150 ×75 cm to
240 × 90 cm depending on the required capacity.
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Pitting and dehulling machines
These machines consist of emery-coated rollers, cylindrical or slightly tapered, rotating in a cage of a
perforated sieve. Cylindrical rollers are mounted at an incline, whereas the tapered rollers are
mounted perfectly horizontal. These arrangements help in easy movement of the pulse. The size of
different cylindrical rollers varies from 75 × 25 cm to 90 × 35 cm. The tapered rollers come in
different sizes, such as 17.5 × 20 × 60 cm to 35.0 × 45.0 × 90 cm. The annular gap between the roller
and the wire mesh screen varies from 2 to 4 cm depending on the type and size of the pulse used. The
power requirement, capacity, roller size, and speed of the rollers are all interrelated; hence, they vary
from fabricator to fabricator. The inlet and outlet of the roller machine can be adjusted for regulation
of flow rate and retention time.
The granular size of the emery grits used depends on the type of the pulse milled. Normally, it varies
from 14 to 16 to 36 to 40 mesh (BSS). Generally, fine-grade emery is used for pitting of almost all
pulses. Rough emery (14-16 mesh) is used for dehusking of pulses such as pigeon pea and chickpea,
whereas fine emery (36-40 mesh) is used for dehusking pulses such as black gram, green gram, and
lentils. Normally pitting is done at a lower peripheral speed (610 – 670 m/min) whereas for
dehusking, particularly for pigeon pea, high peripheral speed of 850 – 975 m/min is employed. Other
pulses such as black gram, green gram, and chickpea are generally dehusked at a lower peripheral
speed of 610 – 670 m/min. The oiling and watering systems are essentially screw- or paddle-type
mixers with conveyor units. The screw is slowly rotated (50 – 70 rpm) to achieve proper mixing of
oil-water with the grain. The length and width of the conveyors range between 1500 and2500 and 200
to 300 mm, respectively.
Splitting machines
The final product of the pulse milling industry is the dehusked split cotyledon. During processing, a
mixture of dehusked and unhusked grains is obtained. Fully dehusked, un-split grains are split in two
after water treatment and sun drying. In some pulses such as black gram, the seed is split without any
treatment. For splitting, various machines including the under-runner disk (URD) shelters, vertical or
horizontal attrition mills, roller machines, or impact machines are used. Under Runner Disk Shelter is
a machine used for splitting dehusked black gram, chickpea, lentil, pigeon pea, and soybean. It has
two horizontal disks with emery coating of 12-mm thickness. The upper disk is stationary; the lower
one rotates to cause splitting of dehusked pulse. The capacity of a machine depends on its size and
speed. The Sheller machines cause breakage as high as 30-40% particularly if the grains are not
thoroughly size-graded. Revolutions of the disks, peripheral speed as determined by the speed of
rotation and diameter, roughness of contact surfaces and their parallelism, the distance and duration
the grains roll (under pressure) between the revolving disks play important roles in splitting or
breakage in these machines. A modified version of this consists of an upper stationary disk is of
rubber, with shore hardness of 40. This machine handles grain gently and results in less breakage.
Attrition mills of vertically or horizontally rotating stone disks or emery disks are also used to split
pulses. Vertical or horizontal grinders or under-runner disk shelters are generally used for splitting
chickpea, whereas black gram is split using attrition mills. An impact-type machine is very commonly
used for splitting the dehusked grains. It consists of a mild steel blade impeller mounted on a shaft
enclosed in a casing. The dehulled seed is fed to the machine and rotating blades throw the seeds on
the hard body (casing) of the unit, causing the splits. The seed is split by impact. The splitting roller is
generally similar to the dehusking roller. However, the size of the emery grits (which reflects the
smoothness or roughness of rollers) varies from pulse to pulse. A course emery coating is required for
the splitter roller. The rollers are used for splitting green gram, pigeon pea, lentil, and others.
A box-type aspirator with a suction fan is generally used for separation of husk and powder. Brokens
are separated by appropriate sieves, which are mixed later with husk and powder and sold as cattle
feed. Cyclone-type separating systems are being introduced in a few pulse mills in India for
improving efficiency and reducing dust pollution. Separate machines, similar to reciprocating-type
screen graders, are generally employed for separation of splits from dehusked whole grains. An
appropriate combination of perforated and slotted sieves is used for the separation of brokens, splits,
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and whole grains. The final treatment, polishing, is an optional operation in the pulse-milling industry
before packing. This is done to provide a luster and improve the consumer appeal. Usually, a screw
conveyor, with or without nylon ropes wound on to the shafts and flights, is used for this purpose.
Depending on the consumer need, different polishing materials, such as water, oil, or soapstone
powder are applied on to the split surface.
Dehulling losses
The primary objective of dehulling is to remove only the seed coat from the cotyledons, but quite
often-noticeable amounts of cotyledon material and germ are also removed during the milling
operation. As a result, considerable quantitative and qualitative losses occur during dehulling of
pulses. The dehulling losses would depend primarily on the machinery employed for dehulling and
the characteristics of the pulse being milled. The dehulling losses in terms of brokens were quite high
(24.6%) in the stone grinder, and this might have been due to the attrition action of the stones
employed for dehulling in this method. In commercial mills, product yields approach only 70%,
which is much lower than the theoretical yield. The average dehusked splits yield from household and
traditional commercial dehulling methods varied from 68 to 75%, which was 10-17% less than the
theoretical average value close to 85%. Table 3.13 summarizes the data collected from commercialmilling systems in terms of yields of dehusked splits, powder, brokens, and husk fractions for
different pulses milled in large- and small-scale-dehulling systems.
Table 3.13. Dehulling losses in various pulses
Pulse
Pigeon pea
Chickpea
Lentil
Green gram
Black gram
Large-scale Processing
Husk +
Dehusked
Brokens (%)
powder (%)
splits (%)
72-78
75-80
76-81
70-78
70-77
2-8
1-6
3-10
5-10
3-8
18-25
14-23
10-21
17-24
17-25
Small-scale Processing
Dehusked splits Brokens
Husk +
(%)
(%)
powder (%)
55-70
65-70
68-75
60-75
65-75
15-20
10-15
8-14
10-15
8-14
15-20
15-20
10-15
8-15
10-15
3.2. Postharvest Technology of Coffee and Spices
Coffee
Processing
Post-harvest coffee processing has historically involved trio goals. The first is to determine the
method of processing that delivers the best tasting coffee for a particular market where coffee is sold.
The second is to process the coffee in the most efficient and least expensive manner. There are two
ways coffee can be processed - dry (‘natural’) processing and wet (‘fermented and washed’)
processing. In most cases, wet processing is regarded as producing a higher quality product. However,
some areas prefer dry processed coffee for its ‘fuller’ flavor.
Dry Process Method
The traditional dry or "natural" process is the oldest and most straightforward method to obtain coffee
beans. The first process involves cleaning to remove dirt, leaves and twigs, dry or undeveloped berries
and stones and soils. The cleaned coffee cherries are then either spread out on mat or clean surface to
dry naturally in the sun or placed in machines called coffee driers. The cherries must be raked and
turned often, to prevent mold and mildew from occurring during the duration of up-to-two weeks so
they may lay to dry. Mechanical drying is faster, usually less than two days, but the cherries must also
be turned often and hot air evenly distributed. The beans dry with their mucilage and pulp intact i.e.
the full cherry is dried as it leaves the tree becoming the black dry. Dry processed coffees can exhibit
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store variance from cup to cup and a slightly lower acidity but fuller body than their wet processed
counterparts can. Some say, "the drying of the whole cherry imparts full body and natural sweetness
to the beans." Dry processed coffees, while once viewed as inferior to wet processed coffees can now
fetch significant premiums in their own right. Certain Sumatran coffees have become extremely
expensive and main Brazilian estate coffees have followed in this emerging pattern. Many as an
essential element of a great espresso blend view natural processed coffees. The coffee cherries are
dried immediately after harvest. This is usually sun drying on a clean dry floor or on mats. In largescale production, the drying surface may be built from concrete. The bed depth should be less than 40
mm and the cherries should be raked frequently to prevent fermentation or discoloration. However,
there are problems associated with this method. The most serious problem is dust and dirt blown onto
the produce. Another problem is rainstorms often appear (even in the dry season) with very little
warning, this can soak the produce very quickly. Finally, labor has to be employed to prevent damage
or theft. Sun drying is therefore not recommended.
Solar drying
Figures 4.26 and 4.27 are designs for two solar driers - the solar cabinet drier and the Excel solar
drier. The coffee should be placed in the trays in the solar drier. The layer of the crop should be no
deeper than one inch (3cm) and it is better if the whole tray area is covered. The drier should be ready
as early in the day as possible so that all possible sunlight hours are used. The coffee should be stirred
regularly so that a uniform coloration is formed. At night, the crop should be placed in a cool dry
room.
Fig. 4.26. The solar cabinet drier
Fig. 4.27. The exell solar drier
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Artificial driers
In the wet season, solar drying of produce is difficult. Rain is very unpredictable and frequent. Solar
driers will prevent the coffee getting wet. However, due to the low level of sunlight, solar drying can
take a long time. This can lead to mould growth. An alternative drier is needed.
Hulling
The dried cherry is then hulled to remove the pericarp. This can be done by hand using a pestle and
mortar or in a mechanical huller. The mechanical hullers usually consist of a steel screw, the pitch of
which increases as it approaches the outlet so removing the pericarp. The hulled coffee is cleaned by
winnowing.
Wet process method
Traditionally "Washed" coffees are processed using a large amount of water. Freshly picked cherries
are first sent to water tanks for density separation. Overripe and partially dry cherries, having lower
density, float to the surface of the water tank whereas the denser, unripe and ripe cherries sink to the
tanks bottom. The cherry is then transferred to a pulping machine, or pestle and mortar, which
removes the outer fleshy material (mesocarp and exocarp) leaving a bean covered in mucilage.
Pulping
Pulping involves the removal of the outer red skin (exocarp) and the white fleshy pulp (mesocarp) and
the separation of the pulp and beans. Immature cherries are hard, green, and very difficult to pulp. If
the coffee is to be wet processed, correct harvesting is essential. The two most common pulpers and
most suitable for small-scale units are the drum and the disc pulpers.
Drum pulpers
This involves a rotating drum with a punched sheet surface and adjustable breastplate between which
the coffee cherries are pulped, the pulp and the beans separated (Figure 3). The distance between the
drum and the breastplate has to be adjusted so that the pulp is removed without the beans being
damaged. These can be manually operated or attached to a treadle or bicycle. For larger scale units,
motorized drum pulpers are available.
Disc pulpers
The same concept is involved with the disc pulper. The only difference is that rather than the cherries
being squeezed between a breast plate and a drum, a disc with a roughened surface is used.
Mucilage removal
The amorphous gel of mucilage around the bean consists of hemicelluloses, pectic substances, and
sugars and is insoluble in water. This can be removed by chemical methods, warm water or by an
‘agua pulper’. However, for small-scale units the only feasible method is fermentation. Fermentation
involves the beans being placed in plastic buckets or tanks and left until the mucilage has been broken
down. Natural enzymes in the mucilage, yeasts, and bacteria work together to breakdown the
mucilage. The coffee should be stirred occasionally and every so often a handful of beans should be
tested by washing them in water. If the mucilage can be washed off and the beans feel gritty rather
than slippery, the beans are ready. The beans should then be washed immediately as ‘off’ flavors
develop quickly.
The denser cherries are then pressed again in water, between grated screens that removed the bulk of
the cherry pulp. However, there is still another layer that needs to be removed- the mucilage. The
beans are again immersed in water, and allowed to ferment for anywhere front a few hours to a few
days. The fermentation does two things-it breaks down the cellulose of the mucilage layer covering
the parchment husk enclosing the beast, and, it is generally agreed, increases the acidity of the coffee.
It also adds increased complexity and elegance. After this fermentation step, the coffee could also be
run through long channels that served to separate the coffee according to different densities.
Several companies have developed a new generation of pulpers that consume little and even no water.
175
Some have machines, which can handle cherries with any degree of maturation, front fully mixed to
completely ripe and pulp only the high quality ripe ones. However, for best quality of coffee selective
picking of the ripe cherries is highly recommended. Ecological wet milling proposes the removal of
the mucilage by friction in machines called mucilage removers that consume and contaminate much
less water than the traditional fermentation tanks. Mucilage removers can also be used after partial
fermentation to complement the removal of mucilage. Whether to use fermentation or mechanical
means to remove the mucilage is today the topic of intense arguments by quality experts. However,
the need to protect our environment may hold the last word in favor of mechanical removal. Figure
4.28 shows separartion of pulp and beans.
Fig. 4.28. Separation of pulp and beans (1- Rotary drum, 2- Breast plate, 3- Separating plate, 4- Receiving trough, 5Cherries, 6- Beans, 7- Pulp)
Semi -washed method
The semi-washed "pulped natural" Arabica coffees are considered a good base for the best espresso
blends which is important to note since espresso is the fastest growing coffee preparation system in
the world. This method of processing uses the density separation method and de-pulping without the
use of the mucilage removal step. In some cases, partial removal of mucilage is done mechanically.
The beans are dried without the pulp but enveloped by all mucilage or some of it (when dry it will be
brownish colored parchment, the darker the brown the more mucilage is left behind).
The semi washed system produces the same cup as natural coffee along with the advantage that there
is no risk of unripe cherries interfering with the cup. Either method, it is understood, will yield coffees
that are sweeter and less acidic than those that undergo a fully washing process. The critical aspect of
post harvest coffee processing is to understand that almost every processing operation has a unique set
of challenges and opportunities from both a quality and cost control perspective, and that almost every
situation will yield a totally unique result. It is therefore critical for farmers and processors to be
aware of all the appropriate choices at their disposal in order for them to achieve the maximum quality
at the lowest possible cost.
Parchment drying
Wet Parchment coffee coming out of a wet mill must be dried to about 11-12% moisture content. This
is accomplished by letting the parchment beans dry in the sun or through some type of mechanical
drying. The beans, as in the dry process, require constant raking to avoid mold and bacterial growth if
they are dried on surfaces or screens. It is pretty well established at this point, that no particular drying
method is superior from a quality point of view. Each method has its own risks and advantages.
Mechanical methods can overheat the beans and dull their flavor if file machines are not properly
designed or operated. Suit drying can take too long and dull and/or muddle flavors or introduce
176
bacterial and fungal taints. The method chosen depends on the resources of the processor and the costs
of the various inputs in a given situation. Ambient temperature and humidity in addition to naturally
present microbes, can also affect the drying method that is finally chosen. The full wash helps to
enhance the acidity at the expense of some of the body. Once the coffee is dried to the appropriate
moisture level it can either be stored to await shipment, or in some situations to cure in a step that
some farmers and millers believe improves and integrates the coffee's flavor by mellowing it and
reducing the potential harshness that many newly harvested and processed coffees can have.
Roasting and manufacturing coffee
Each species of coffee comprises many different varieties, forms, and types and the specific
characteristics of the beans varies. In addition to these botanical criteria there are also less obvious
characteristics which occur as a result of various influences such as the ecological environment
(sometimes the soil), cropping techniques, etc. Some of these influences are genetic in origin, while
others are phenotypic or environmentally related. They are manifested by pronounced differences in
size, shape, color, and even texture of the beans. The techniques used to process the coffee, the care
taken during its processing, and the way the beans are stored before shipping also influence the
appearance of the beans, for example, more or less complete skin removal, and particularly color,
which may be affected by excess fermentation and insufficient or irregular drying. Finally, aging
changes the hue of the beans. This is easily recognized by merchants. The coloring of the beans
becomes generally more subdued the longer they are stored. These visible criteria are extremely
important from a commercial point of view. In a way, they provide a key to any sample of beans: their
botanical grouping, geographical origin, method of preparation, age, storage conditions etc.
Roasting and associated operations
The aromatic qualities of coffee only become apparent once the beans have been exposed to high
temperatures during pyrolysis, which is still referred to as 'roasting' or 'grilling'. In addition to changes
in its external appearance (color, size and texture) during the course of this operation, the product is
the centre of complex chemical changes, some of which generate the particular aroma and taste of
coffee. Coffee roasting is preceded by various operations including cleaning and dusting to remove
the foreign matter from the beans (pieces of husk or parchment, stones, earth, string, nails, etc.). Many
different types of equipment are suitable for this job, the most modern of which are the pneumatic
separators. The beans are then stored in partitioned silos prior to roasting.
Progressive temperature increases have the following effect on coffee: at about 100°C, the beans
begin to turn from green to yellow. The drying is accompanied by a loss of water vapor and the scent
of toasted bread. Above 120°-130°C, the bean turns a chestnut brown, which gradually darkens. At
150°C the coffee begins to give off an aroma like that of roasted seeds, and the development of the
characteristic aroma begins at about 180°C, at which temperature the combustion gases appear in the
form of bluish white curls, with a release of CO2 and CO. The beans then turn brown and their volume
increases. At a higher temperature, more gas of a darker color is released and the aroma has
completely developed. The beans expand, crackle, and a shiny exudates collects on the surface. At
about 270°C, the release of smoke is complete and the beans turn black and dull and cease to expand.
At about 300°C they become black and sooty, and crumble at the slightest pressure. By this time, the
aroma has completely disappeared and the coffee is carbonized. Specialists place the 'roasting zone'
between 185° and 240°C the optimum temperature being between 210° and 230°C. Above this
temperature, over-roasting begins. Both the roasting temperature and the way process is conducted
have a considerable effect on the quality of the coffee. A series of reactions take place during roasting
including dehydration, hydrolysis, desmolysis, and catalysis. The optimum intensity of each reaction
occurs at well-defined temperatures and some of these reactions overlap. In practice, the objective of
roasting is to develop the maximum potential of the aromatic and organoleptic qualities of the bean
according to the tastes of the clientele.
177
Roasting is still carried out very empirically in many -roasting- plants. Professional methods,
however, require an exact knowledge of green coffee characteristics, in order to identify not only the
species, varieties, and types from all production areas, but also their particular characteristics,
depending upon their origin, where they have been stored, their grade, the rate and nature of their
impurities, etc. Each type will react differently to the various stages of roasting process such as length
of time- rate of expansion, color of the beans, weight loss, etc. The roaster must be familiar with these
factors in order to obtain the maximum organleptic qualities from each batch, with a minimal loss of
substance.
The roasting process normally lasts for between 12 and 15 minutes. It is faster with certain types of
equipment than others. For example, it can be completed in five minutes using the American
continuous roasting technique. On the other hand, there are also slow roasting techniques, which
require about 25 minutes. Recuperating the volatile aromatic substances released at the time of
roasting and carried out with the hot gases has been the subject of several studies. While roasting
gives coffee its taste and aroma, it also changes the bean in certain way. First, the bean loses weight
due to the evaporation of water from the green coffee; the extreme limits of this evaporation are
between 14 and 23%. The amount of weight lost depends upon the level of moisture in the green
bean, the botanical origin, the methods of preparation at the production site, storage conditions, the
roasting method used, etc. Moisture evaporation is not the only element responsible for the loss of
weight. There is also the elimination of the silver skin (0.2 to 0.4%) and the release of certain volatile
elements. There is an increase in volume as the coffee is roasted. This phenomenon, which is due to
the formation and expansion of gas between 180° and 220°C, also induces the endosperm to increase
in volume. This is manifested in a volumetric increase of about 50 to 80% (the extremes are between
30 and 100%). The botanical origin, production area, amount of moisture present, and the roasting are
all criteria that may affect the intensity of expansion. Whatever the cause, the potential for expansion
is an important characteristic from a commercial point of view. Buyers are attracted by large, wellformed beans, and are rarely insensitive to the appeal of larger packages. Bean color is significantly
affected by roasting. It is particularly dependent upon the intensity and duration of the operation.
Cooling the beans rapidly at the end of the roasting period can also make a slight difference. Waxing
the beans, when allowed, also affects the color.
Roasting equipment and techniques
There are two roasting techniques, heating by convection and heating by conduction, which differ in
that in the former, the coffee, is in contact with hot gases while in the latter it is in direct contact with
a hot surface.
Heating by convection
This method has two variations: hot air roasting, where the beans are in contact with the hot air
produced by a generator, and flaming, where the beans are directly exposed to a flame. In the first
variation, which is now the most common and widespread, the hot air is produced in a combustion
chamber and is passed through the coffee by a blower. Gases are released from the coffee and mix
with the air, which is then removed by a suction system. The silver skin is also released from the
beans and removed by the air currents. The drum rotates slowly and blades mounted in the drum
ensure a thorough mixing of the beans and the diffusion of hot gases. A probe is used to take samples
for monitoring the operation. Various types of measuring equipment control temperatures. The coffee
is removed by a large run-off valve, which is operated by a counter-weight. The heating design varies
depending upon the fuel used. With coke, a special oven is necessary; with gas or oil, special burners
are normally required. The application of this technique has given rise to various systems and models
of equipment. With flaming, the coffee is subjected to the direct effect of a flame produced by the
combustion of a gas conveyed by a duct mounted in a rotating axis in the roasting chamber. Agitators
to prevent some of them from being overheated actively mix the beans. This technique is not as
widespread as the one previously described.
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Heating by conduction
This is the oldest method in use. It involves the transfer of heat by conduction. The drum or metal ball
containing the coffee is rotated either manually or by a motor above a firebox fueled by charcoal, gas
or electricity. In smaller models stationery circular pans with rotating blades for agitating the beans
are commonly used. This technique is being used less and less, except for small family-run
operations. Whatever the method of roasting used, when the coffee has reached the desired level of
roasting, it is poured out through the opening of the drum into a shallow cooling tank, which has a
large diameter. Here it is mixed by agitators, and a ventilating fan directs a cool current of air towards
the lower part of the tank. The temperature decreases rapidly, thus eliminating any risk of overroasting.
The size of the equipment varies from small one with a few kg capacity to extreme are large,
continuous roasters which have an hourly output of between 2 and 4 tones. The technology has
developed to the extent that some large continuous roasting equipment completes the roasting process
in a residence time of about 4 to 5 minutes. In this equipment, the coffee is carried along by blades
and passes through a long, perforated, horizontal cylinder, which rotates slowly at a rate of four to six
turns per minute. A hot air current blows through it, the temperature of which is rigorously controlled.
Another commonly used roasting technique is the fluidized bed system where coffee is suspended in a
roasting chamber by a vigorous hot air current. The roasting time is about 3 to 5 minutes depending
upon the nature of the coffee and the degree and quality of roasting desired. Finally, 'high yield' or
'super yield' roasters exist which enable the coffee to be roasted within a very short Period: about a
minute and a half.
Commercial blends
Few coffees have all the characteristics necessary to provide the beverage with the ideal aroma and
taste. In the roasting process, therefore, several specifically selected types must be blended so that
their different qualities complement each other. An average of three to five types of coffee may be
associated in a blend, but it is usual to find even more in certain highly superior blends. Blending may
be carried out before or after roasting. If the characteristics of the coffees are compatible (moisture
content, grade, percentage of small beans and pea berries etc.) it may be carried out prior to roasting.
Coffees are blended after roasting if there is too great a variation in type. However, these are not the
only considerations that guide the manufacturer. The price factor also helps to determine the choice of
components, depending upon the purchasing potential of the clientele, as well as seasonal supplies.
Packaging roasted coffee
Roasted coffees rapidly lose their flavor and aroma. The loss is very noticeable after two to three
weeks. Later on, a rancid taste develops which persists. Roasted coffee easily absorbs atmospheric
moisture. Its qualities become rapidly altered when its moisture content exceeds 6%. In order to avoid
this, stock must be renewed regularly, at least for superior qualities. Alternatively, an expiration date
must be displayed on the package or sufficiently airtight packaging should be used which can preserve
the qualities of the coffee for a longer period. The atmospheric oxygen is the main factor responsible
for the loss in quality as it reacts with certain components, especially the fats. The alteration is mainly
due to oxidation of substances on the bean's surface. This is why some coatings inside the packages,
which can absorb fats, have a harmful effect on the product. Packaging materials used for roasted
coffee must therefore be odorless, and impermeable to water vapor and fats. The technology of the
packaging material has developed such that compound materials, combining glued or laminated
products, plastic films, polythene, textiles, metal, (aluminum-cellulose compound) etc. are used for
packaging. Airtight vacuum packaging or the inclusion of an inert gas in airtight containers (or
packages) is the most satisfactory solutions in terms of conservation, provided the package is not
opened.
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Ground coffee
Another form that coffee appears in the market is in powder form. Its use is favored because it is less
time-consuming to prepare, but it does not preserve the aromatic qualities of the product. In fact, as
soon as the package is opened, the grounds are much more sensitive than the bean to the oxidation
process (becoming rancid), due to their large surface area. The contents of the package should
therefore be stored in a hermetically sealed container. With this practice, the visual attraction of high
quality beans has faded over the years in favor of ground coffee, the nature (except for the obligatory
indication of the species), composition, and origins of which are poorly defined.
Spices
Cinnamon
Harvesting
The plant is harvested during the wet season since the rains facilitate the peeling of the bark.
Harvesting involves the removal of the stems. This takes place early in the morning. The tender stems,
with diameters of less than 1.2cm, are removed and used for mulching. Stems with diameters of more
than 5 cm are not used to prepare cinnamon bark. The leaves are removed and can be used for oil
distillation. The soft outer bark is stripped off using a fine rounded rasp knife. The stripped stem is
rubbed with a brass rod to loosen the inner bark. Cuts are made around the stem at 30 cm intervals
using a small pointed knife. This knife should be stainless steel or brass to prevent staining. The
longitudinal cuts are made on either side of the stem and the bark carefully eased off using pointed
knife and rubbing rod.
Processing
The bark is left to ferment in bundles for twenty-four hours. The 'compound quills' are placed on coir
rope racks and dried, in the shade to prevent warping. Drying continues in the sun and may require a
total of three or four days. Good quills should be about 2.5 cm wide by 1.5 mm thick. The clean, lightcolored bark curls as it dries, assuming the appearance of a quill. The curled pieces of peeled bark
(quills) are placed one inside another to make 1 m long 'compound quills' that are known as "pipes".
These quills are then selected for export, the best ones are placed on the outside and broken and small
pieces in the center. The quality of the product is dependent on the thickness of the bark, the
appearance and the aroma and flavor. The cinnamon quills are divided into groups based on diameter
and number of quills per kg each of which is further divided into specific grades. Cork-free ones of
finest, smoothest quality being graded "00000." The coarsest being graded "0" and the “chips,”
“pieces,” “quillings” (broken pieces), “featherings,” etc. graded accordingly. Any pieces of bark less
than 106 mm long are categorized as quillings. Featherings are the inner bark of twigs and twisted
shoots. Chips are trimmings of quills, outer and inner bark that cannot be separated or the bark of
small twigs. The British Pharmacopoeia defines cinnamon as the dried bark of the Cinnamonum
zeylanicum tree. It should contain less than 2% foreign matter by weight, not less than 1% volatile oil.
Grinding adds value, but it should be done carefully. A whole, intact product can be easily assessed
for quality whereas a ground product is more difficult. There is a market resistance to ground spices
due to fear of adulteration or the use of low quality cinnamon. This can only be overcome by
producing a consistently high quality product and gaining the confidence of customers.
Packaging and packaging materials
Packaging of cinnamon, especially ground requires polypropylene bag. Polythene cannot be used as
the flavor components diffuse through it. The bags can be sealed simply by folding the polypropylene
over a hacksaw blade and drawing it slowly over the flame of a candle. However, this is extremely
uncomfortable as the hacksaw blade heats up and burns the hands of the operator. This is however, a
very common technique. A sealing machine will speed this operation up considerably and produce a
much tidier finish (which is very important). The cheapest machines have no timing mechanism to
show when the bag is sealed and they have a tendency to overheat. Sealing machines with timers are
desirable. The machines come in many sizes. For most work, a 20 cm sealer is sufficient. Eye
180
catching labels should be sealed above the product in a separate compartment and holed so the
package can be hung-up in the shop.
Wholesale export
For wholesale export, the quills are packed in compact cylindrical bales of 50 kg and wrapped in jute
cloth.
Black Pepper
Harvesting
By definition, 'processing' does not involve harvesting. However, one cannot produce a good product
from badly harvested materials. Correct harvesting techniques could be said to be the most important
factor in the production of a high quality final product. The main problem is immature harvesting. The
main reasons for immature harvesting are the fear of theft. If the crop is picked correctly when it is
mature, the higher yields and higher value of the final product may offset the losses due to theft.
Through extension officers, correct harvesting should be encouraged. However sometimes immature
pepper receives a higher price than mature pepper due to purchase by food processors due to its higher
percentage of flavor components. The pepper spike should be picked when one or more of the berries
start going yellow/orange. The berries should be hard to the touch. In most countries, the harvested
pepper berries are removed from the spikes before drying. This can be done by hand, beating with
sticks or trampling on the pepper spikes.
Cleaning
A clean product is essential. The major problem for the export of pepper by small-scale farmers is the
production of a sufficiently clean product. The first step is to remove dust, dirt, and stones using a
winnowing basket. This can be done in the same way as for rice. Someone used to this work can
remove the dirt, dust and stone quickly and efficiently (they can clean over 100 kg of pepper in an
eight-hour day). There are machines that can be bought or made that can remove the dust, dirt and
stones. However, for a small-scale unit, winnowing the crop by hand is the most appropriate system.
After winnowing the crop needs to be washed in water, for quantities of up to 50 kg a day all that is
needed is two or three 15 litre plastic buckets. The crop should be washed by hand and drained two or
three times. For larger quantities, a 1 m³ sink/basin with a plug hole needs to be constructed. This can
be made out of concrete. However, the water must be changed regularly to prevent recontamination
by dirty water. Only potable water should be used. The pepper berries can be blanched before drying
by dipping them in boiling water for ten minutes.
Drying
This is by far the most important section in the process. The inability to dry the produce will, at the
very least, slow down the whole process and possibly lead to mould growth. Any pepper with even a
trace of mould cannot be used for processing. The sale value of moldy pepper can be less than 50%
the normal value. In extreme cases, the whole crop can be lost. To get the full black color of dried
pepper it needs to be dried in direct sunshine. This can be achieved by sun drying, solar drying or in a
combined solar and wood burning drier. During the dry season, sun drying is usually adequate to dry
the produce. The simplest and cheapest method is to lay the produce on mats in the sun. However,
there are problems associated with this method. Dust and dirt are blown onto the crop and unexpected
rain storms can re-wet the crop. A solar dryer avoids these problems. The simplest type is the cabinet
solar dryer, which can be constructed out of locally available materials (e.g. bamboo, coir fiber, or
nylon weave). For larger production (over 30 kg/day), high capacity solar dryer could be used.
However, the construction costs are greater and a full financial evaluation should therefore be made to
ensure that a higher income from better quality spices can justify the additional expense. During the
wet season or times of high humidity, which often coincides with the harvest of the spices, a solar
dryer or sun drying cannot be used effectively. An artificial dryer, who uses a cheap energy source, is
necessary. This may be a wood or husk burning dryer or a combined wood burning and solar dryer.
Care needs to be taken to prevent over drying of the crops, which results in the loss of flavor
181
components. A drier operator will soon learn how to assess the moisture content of the crops by hand.
The final moisture content should be less than 10% wet basis.
Grading
In some cases the crop needs to be graded, for example, high quality packaged products. Pepper is
graded by size, color, and relative density. Color grading will have to be done by hand. Machines can
be bought or made that will grade the pepper according to its size or relative density. However, a
trained person with a winnowing basket is more appropriate for small-scale production.
Grinding
Grinding adds value, but it must be done carefully. There is a market resistance to ground produce due
to fear of adulteration producing a consistently high quality product and gaining the confidence of
customers. There are two types of grinders - manual grinders and mechanical grinders. A grinding
mill has to be placed in a separate and well-ventilated room because of dust. Many manual grinders
could be used to grind pepper. An experienced operator can grind about 20 kg in an eight-hour day.
However, this is hard and boring work. A treadle or bicycle could easily be attached to the grinder,
making the work easier. With this system, one person could grind about 30 kg in one day. Work needs
to be done to find out the degree of fineness the consumer wants. For small-scale production (up to
100 kg/day), a series of these grinders is all that is needed. For larger scale production units, a
mechanical grinder would be required. Horizontal plate, vertical plate, or hammer mills are suitable
for grinding pepper. A grinding mill has to be placed in a separate and well-ventilated room because
of dust. Packaging
Packaging material Packaging of pepper especially if it is ground requires polypropylene. Polythene
cannot be used as the flavor components diffuse through it. The bags can be sealed simply by folding
the polypropylene over a hacksaw blade and drawing it slowly over the flame of a candle. However,
this extremely uncomfortable as the hacksaw blade heats up and can burn the hands of the operator.
However, this is a very common technique. A sealing machine will speed this operation up
considerably and produce a much tidier finish, which is very important. The cheapest sealing
machines have no timing mechanisms to show when the bag is sealed and they have a tendency to
overheat. Sealing machines with timers are desirable. The machines come in many sizes. For most
work a 20 cm sealer is sufficient.
Storage
A well-designed and secure store is essential. The optimal conditions for a store are a low
temperature, a low humidity and free from pests. The store should be located in a shaded, dry place.
To keep humidity as low as possible only fully dried products should be stored in it. The produce
should be checked regularly and if it has absorbed too much moisture, it should be dried again. To
prevent rodents entering, the roof should be completely sealed. Mosquito netting should be placed
over the windows and doors should be close fitting. Standards are set as in Table 3.14.
Table 3.14. Standards
International Standards Organization
British Standards
American Spice Trade Association
Standards
Moisture
Content (%)
by weight
Max
12.0
12.0
12.0
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Extraneous
Matter (%)
by weight
Max
1.5
1.5
1.0
Lights (%)
by weight
Max
Pinheads (%)
by weight
Max
10.0
10.0
4.0
4.0
4.0
-
Oils extraction
Pepper oleoresin is extracted from black pepper by solvent extraction and is used to flavor foods.
Furthermore, the pepper is crushed and then undergoes steam distillation yielding from 1 to 2.4 % of
an essential oil that represents the aromatic odor of the spice. The sharp, pungent taste of pepper is
contributed by the resin chavicine and the burning aftertaste by the crystalline alkaloid piperine, both
components of oleoresin of pepper, obtained from the ground dried berries through solvent extraction.
Both oil of pepper and oleoresin of pepper are utilized in the food industry to flavor sausages, table
sauces, canned meats, and salad dressings.
Ginger
Fresh ginger
Fresh is usually only eaten in the area where it is produced although it is possible to transport fresh
roots overseas. Both mature and immature rhizomes are consumed as a fresh vegetable.
Preserved ginger
Preserved ginger is only made from the immature rhizomes. Candied ginger, crystallized ginger, and
preserved ginger, all considered to be confections rather than spices are prepared from fresh green
rhizomes that have been cleaned, peeled, shaped, boiled, and preserved in sugar solutions of varying
strength. Preserved ginger is produced on a large scale in Hong Kong and Australia. Most preserved
ginger is exported. Making preserved ginger is not simple, it requires a lot of care and attention to
quality, only the youngest, most tender stems of ginger should be used.
Dried ginger
Dried ginger spice is produced from the mature rhizome. As the rhizome matures, the flavor and
aroma become much stronger. Dried ginger is exported, usually in large pieces, which are then ground
into a spice in the country where it is used. Dry ginger is available ground, cracked (broken into bits),
or whole. As a flavoring it has a wide range of uses: Ground ginger is used extensively in
gingerbread, pies, cookies, pickles, puddings, and the preparation of Oriental meat dishes such as
"Hawaiian Gingered pork," Cracked and whole ginger are used in making flavored syrups and
pickling vinegar. Dried ginger can be used directly as a spice and for the extraction of ginger oil and
ginger oleoresin.
Processing ginger
There are two important factors to consider when selecting ginger rhizomes for processing:
•
•
the stage of maturity at harvest; and
native properties of the type grown.
Ginger rhizomes may be harvested from about 5 months after planting. At this age, they are
immature. They are tender with a mild flavor and are suitable for fresh consumption or for processing
into preserved ginger. After 7 months, the rhizomes will become less tender and the flavor will be too
strong to use them fresh. They are then only useful for drying. Mature rhizomes for drying are
harvested between 8 and 9 months of age when they have a high aroma and flavor. If they are
harvested later than this, the fiber content will be too high. Gingers grown in different parts of the
world can differ in their native properties such as taste, flavor, aroma, and color. This affects their
suitability for processing. It is most important when preparing dried ginger which needs rhizomes
with a strong flavor and aroma. When drying ginger, size is also important. Medium sized rhizomes
are the most suitable for drying. The large rhizomes often have a high moisture content, which causes
problems with drying.
Making dried ginger
Dried ginger is available in many forms. The rhizomes may be left whole or they may be split or
sliced into smaller pieces to accelerate drying. Sometimes the rhizomes are killed by peeling or
boiling them for 10-15 minutes. This results in a black product that can be bleached using lime or a
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sulphurous acid. The only product, which is acceptable for the UK market, is cleanly peeled dried
ginger. Dried ginger is produced according to the following steps:
•
•
•
•
The fresh rhizome is harvested at between 8 and 9 months of age;
The roots and leaves are removed and the rhizomes are washed;
The rhizome is killed. This is done by peeling, rough scraping or chopping the rhizome into slices (either
lengthwise or across the rhizome). Whole, unpeeled rhizomes can be killed by boiling in water for about 10
minutes; and
The rhizome pieces are then dried. This is often by sun-drying. Information on drying foods is included in a
separate technical brief.
Quality of dried ginger
The most important factors to control in the production of dried ginger are:
•
•
•
•
The appearance of the final product - especially for whole roots for export (not so important if the product
is to be ground or used for oil extraction)
Content of volatile oil and fiber - especially for extraction of oils
Level of pungency - especially for the extraction of oils
Aroma and flavor - especially for the extraction of oils
The dried and cured ginger is graded according to quality and appearance-in the best grades each hand
is plump, free from mildew and light buff in color. The aroma should be spicy-sweet and pungent.
The taste should be hot and clean. Quality of the final product is determined by both pre-harvest and
post-harvest factors:
•
•
•
•
•
•
•
The most important factor is the cultivar of ginger grown. This determines the flavor, aroma, pungency and
levels of essential oil and fiber;
The stage of maturity of the rhizome at harvest determines its end use. At 8-9 months of age rhizomes are
most suitable for drying;
When the rhizomes are harvested they should be handled with care to prevent injury;
They should be washed immediately after harvest to obtain a pale color. The wet rhizomes should not be
allowed to lie too long in heaps as they are liable to ferment;
Care should be taken when removing the outer cork skin. It is essential to remove the skin to reduce the
Fiber content, but if the peeling is too thick, it may reduce the content of volatile oil which is contained near
the surface;
During drying, the rhizomes lose about 60-70% of their weight and achieve a moisture content of 7-12%.
Care should be taken to prevent the growth of mould; and
Dried ginger should be stored in a dry place to prevent the growth of mould. Storage for a long time results
in the loss of flavor and pungency.
Chilies
Harvesting
By definition, 'processing' does not involve harvesting. However, one cannot produce a good quality
product from badly harvested materials. Correct harvesting techniques could be said to be the most
important factor in the production of a high quality final product. For processing, chilies should not be
picked until it starts going red.
Cleaning
The crop should be cleaned before processing. The first stage is to remove dust and dirt using a
winnowing basket. This can be made locally from bamboo, palm, or other leaves. Someone used to
this work can remove the dust, dirt and stones quickly and efficiently (e.g. they could clean 100 kg of
chilie in an eight hour day). Small machines are available for cleaning but they are rarely cost
effective. After winnowing the crop needs to be washed in water, all that is needed are two or three 15
litre buckets. For larger quantities, a 1 m³ sink/basin with a plug hole needs to be constructed. This
can be made out of concrete. However, the water must be changed regularly to prevent
recontamination by dirty water. Only potable water should be used.
184
Drying
This is by far the most important section in the process. The inability to adequately dry the produce
will, at the very least slow down the whole process and possibly lead to mould growth or
discoloration. Any produce with even a trace of mould cannot be used for processing. The sale value
of moldy chilie can be less than 50% the normal value. In extreme cases, the whole crop can be lost.
During the dry season, sun drying is usually adequate to dry the produce. The simplest and cheapest
method is to lay the produce on mats in the sun. However, there are problems associated with this
method. Dust and dirt are blown onto the crop and unexpected rain storms can re-wet the crop. A
solar dryer avoids these problems. The simplest type is the cabinet solar dryer, which can be
constructed out of locally available materials, for example, bamboo, coir fiber, or nylon weave). For
large scale drying (over 30 kg/day) larger units, solar dryer could be used. However, the construction
costs are greater and a full financial evaluation should therefore be made to ensure that a higher
income from better quality spices can justify the additional expense. During the wet season or times of
high humidity, which often coincides with the harvest of the spices, a solar dryer or sun drying cannot
be used effectively. An artificial dryer that uses a cheap energy source is necessary. This may be a
wood or husk burning dryer or a combined wood burning and solar dryer. Care needs to be taken to
prevent over drying of the crops. A drier operator will soon learn how to assess the moisture content
of the crops by hand. The final moisture content should be 10% wet basis.
Grading
In some cases the crop needs to be graded, e.g. high quality packaged products. Dry chilies fruit is
graded by color and size this is done by hand. Brighter red color is much preferred.
Grinding
Grinding adds value but it must be done carefully. A whole, intact product can be easily assessed for
quality whereas a ground product is more difficult. There is a market resistance to ground produce due
to fear of adulteration. This can only be overcome by producing a consistently high quality product
and gaining the confidence of customers. There are two types of grinders - manual grinders and
mechanical grinders. A grinding mill has to be placed in a separate and well-ventilated room because
of dust. Many manual grinders could be used to grind chilies. An experienced operator can grind
about 20 kg in an eight-hour day. However, this is hard and boring work. A treadle or bicycle could
easily be attached to the grinder that will make the work easier. With this system, one person could
grind about 30 kg in one day. Work needs to be done to find out the degree of fineness the consumer
wants. The grinding mills then need to be set so that they produce the desired ground product. For
small-scale production, (up to 100 kg/day) a series of these grinders is all that is needed. For larger
scale production units, a mechanical grinder would be required. Horizontal plate, vertical plate or
hammer mills are suitable for grinding chilies. A grinding mill has to be placed in a separate and wellventilated room because of the dust. The grinding mill needs to be adjusted so that it grinds the chilies
to the desired fineness.Chili powder is usually a blend of spices that includes ground chilies, ground
oregano, grounbd cumin, garlic powder, and other ground spices.
Packaging
Packaging of these products, especially if they are ground requires polypropylene bags. Polythene
cannot be used as the flavor components diffuse through it. The bags can be sealed simply by folding
the polypropylene over a hacksaw blade and drawing it slowly over the flame of a candle. However,
this is extremely uncomfortable as the hacksaw blade heats up and burns the hands of the operator.
However, this is a very common technique. A sealing machine will speed this operation up
considerably and produce a much tidier finish (which is very important). The cheapest sealing
machines have no timing mechanism to show when the bag is sealed and they have a tendency to
overheat. Sealing machines with timers are desirable. The machines come in many sizes. For most
work, a20 cm sealer is sufficient. Eye catching labels should be sealed above the product in a separate
compartment and holed so the package can be hung-up in the shop. 185
Storage
A well-designed and secure store is essential. The optimal conditions for a store are: low temperature,
low humidity and free from pests. The store should be located in a shaded, dry place. To keep
humidity as low as possible only fully dried products should be stored in it. The produce should be
checked regularly and if it has absorbed too much moisture, it should be dried again. To prevent pests
entering, the roof should be completely sealed. Mosquito netting should be placed over the windows
and doors should be close fitting.
Onion
There are numerous cultivated varieties (or cultivars) of onions, and through careful selection and
breeding many different sizes, colors, shapes, flavors, and degrees of firmness have been developed.
Although onions are grown domestically in all the major farming. Onions have been specially grown
and developed for dehydration processing. Selections out of the cultivars such as the Southport White
Globe, first developed a century ago in Southport, Connective, that combine the advantageous
features of whiteness, large size, high solid content, superior flavor strength, and adequate seasoning
power are used extensively. The White Creole is another variety of onion widely used in dehydration.
Onion hybrids are beginning to be used and should become increasingly important. Onion crops
produced for dehydration are usually grown under irrigation from specially selected seed. The highly
mechanized harvest follows about seven months after sowing. Prior to dehydration, the onions are
inspected and graded, then peeled, derooted, topped, washed, and sliced to a uniform thickness so that
drying will be even. Approximately 8 pounds of fresh onions produce 1 pound of the dehydrated
product.
Dried onion (dehydrated onion) is produced by eliminating approximately 96 % of the moisture
through tunnel drying on trays, with circulating hot air; or drying by means of a continuous stainless
steel belt upon which the sliced onion is fed and then passed through various chambers with varying
degrees of heat. This low moisture content of about 4 % is essential to avoid deterioration and
maintain stability in the dried finished product. In both these drying methods, the pieces of onion are
neither cooked nor charred. The temperature is carefully controlled so that the onion solids will be
dehydrated very slowly so avoid any discoloration that might cause damage to the flavor. Dried onion,
for use as a condiment rather than as a vegetable, is produced in many different particle sizes, all
suitable for replacing raw onion. Dried onion is reconstituted in about thirty minutes and thus can be
employed in its dry form if the food products to which it is to be added (sauces, gravity, soups, and
the like) contain liquid. It should be noted, however, that large-sized pieces, sold as large sliced onion,
require a longer period for reconstitution.
One pound of instant granulated onion or instant ground onion added to 4 quarts of water is the flavor
equivalent of 10 pounds of raw prepared onion. One pound of either instant minced onion, chopped
onion, or sliced onion, added to 3 quarts of water, is the flavor equivalent of 8 pounds of raw prepared
onion. Food and spice manufactures now pack these various types of dried onion products in cartons
or glass containers, suitable for commercial use in many food products: dried soups, Chili con carne,
Chinese foods gravies, dressings, omelets, vegetables. Spanish rice, salads, meats, onion salt, and
pickles, just to mention a few similarly packaged for the consumer, these convenient, uniformly
flavored, easy-to-store dehydrated onion products are most satisfactory condiments for home use.
Garlic
Garlic stands second to the common onion as the most extensively used member of the cultivated
Alliums. As a condiment, garlic has traditionally been more popular in southern Europe, the
Mediterranean region, and Latin America than in England and Scandinavia. The availability of
dehydrated garlic has stimulated a tremendous growth in its popularity. Much of the credit for this
extraordinary development must be given to the convenience of the dehydrated product, such as
powdered garlic, instant granulated garlic, instant ground garlic, instant minced garlic, chopped garlic,
sliced garlic, and garlic salt. Garlic salt is dehydrated garlic combined with table salt, but the other
forms consist of pure garlic. When the moisture content is as low as it should be, there is very little
186
aroma in either the dried onion or the dried garlic. The characteristics flavors develop when the dried
products are dehydrated, allowing enzyme action to occur. Although the pungent odor of garlic is
strongest in the bulb, it permeates the entire plant. Garlic owes its characteristics odor to the presence
of the pale yellow, intensely obnoxious, volatile oil of garlic, which contains allyl propyl disulfied and
diallyl disulfied. When extracted, it represents a yield of about 0.1 % of the weight of the bulbs. Less
offensive and resembling more closely the true flavor of garlic, dehydrated garlic powder is in far
more demand for flavoring than is oil of garlic, which is used mainly in pharmaceutical preparations.
Processing
For dehydration purpose, the fruit is peeled by hand, topped, and sliced into thin layers. This could be
done manually or using a blade of a household food processor. The sliced garlic can be placed on
trays or clean sheet of cloth and left in the sun. For fast drying, the thickness of sliced material shall
not more than two centimeters thick. Frequent stirring is needed to shorten drying time. Furthermore,
the slices tend to stick one another and form large lumps, which need to be disintegrated during
stirring. In a good sunny condition the slice garlic will be fully dried (4% m.c.) in two days and is
ready for grinding.
Packaging
Ground garlic can be packed in glass bottle, plastic bags and even paper bags. The container need to
have a tight feet cover to prevent loss of aroma. The product needs to be stored in cool dry place.
Fenugreek
Fenugreek was widely cultivated as a drug plant (Semen fenugreek) until the nineteenth century. The
mucilaginous seeds, reputed to have many medicinal virtues, were used to cure mouth ulcers, chapped
lips, and stomach ailments. An ointment prepared from these seeds that was used in earlier European
folk medicine had so repugnant an odor it was called “Greek excrement.” Fenugreek is employed
today in Indian and Ethiopian medicine as a carminative and tonic for gastric troubles. When soaked
in water the seeds smell and produce soothing mucilage said to aid digestion. Fenugreek seed is used
also by Indian women for its alleged power to promote lactation. Ground fine and mixed with
cottonseed, it is fed to cows to increase the flow of milk. Mildewed or &sour& hay is made palatable
to cattle when fenugreek herbages are mixed with it. It is used as a conditioning powder to produce a
glossy coat on horses. Indeed, in the middle ages, fenugreek was recommended as a cure for baldness
in men, and in Java today it is used in hair tonic preparations and as a cosmetic. The powder made
from the seeds is used in the Far East as a yellowish dye. Harem women in North Africa and the
Middle West eat roasted fenugreek seed to achieve a captivating buxom plumpness.
As a spice, fenugreek seeds add nutritive value to foods as well as flavoring. It is an importance crop
in the Middle and Far East where meatless diets are customary for cultural and religious reasons rich
in proteins, minerals, and vitamins, it can be used to supplement the diet and help prevent
deficiencies. Fenugreek is used in less developed areas of the world as a nourishing food and as a
relatively inexpensive condiment. In Egypt and Ethiopia fenugreek is a popular ingredient of bread,
known to the Arabs as hulba, and in Ethiopia going by the Amharic name of abish. In Greece the
seeds, boiled or raw, are eaten with honey. Although the use of most spices in medicine has declined
substantially in recent years. Fenugreek may be an important exception to the rule. Studies in England
indicated that fenugreek seed contains the steroidal substance diosgenin. Diosgenin, at present
obtained mainly from the tubers of certain species of Dioscorea (wild yams) in Mexico and Central
America is of importance to the pharmaceutical industry as a starting material in the partial synthesis
of sex hormones and oral contraceptives. The fenugreek seeds contain about 5 % of a bitter fixed oil
that can be extracted by ether. This oil as an overpowering celery like odor that is extremely tenacious
and in recent years has attracted the interest of the perfume trade. Steam distillation of the seeds has
been attempted, but the oil yields have been very low. Fenugreek seed is available either whole or
ground, as a bitter taste reminiscent of burnt sugar and maple. It is a prominent component of many
curry powders. The processing of fenugreek into powder is not different from other grains. Cleaning,
washing, drying, and milling are all present. Some applications of fenugreek may light roasting of the
187
seeds. Storage of the fenugreek powder does not require special attention different from other ground
cereals.
Cardamom
Cardamom has a strong, unique taste, with an intensely aromatic fragrance. Black cardamom has a
distinctly more astringent aroma, though not bitter, with coolness similar to mint, though with a
different aroma. Today the most important grades of cardamom in the trade are:
•
•
•
•
green pods, artificially dried in kilns or hot-rooms;
sun-dried pods (light-colored, dried in the sun);
decorticated (hulled seeds); and
bleached (pods that have been chemically bleached by fuming with burning sulfur or by hydrogen
peroxide. This type has become less important in recent years.)
Both the seeds and pods of cardamom contain an essential oil, obtained through steam distillation.
The whole fruits (including the seeds), when crushed, will yield 3.5 to 7 % essential oil; the husks
alone yield 5 to 1 % essential oil. Traditionally oil of cardamom has been used in medicine as a
carminative and as a flavoring to disguise the odor of foul-smelling drugs. This expensive essential oil
is used sparingly today by the perfume trade, by a few cigarette manufactures to flavor tobacco, and
by some meat packers to add flavor to sausages. Cardamom is best stored in pod form, because once
the seeds are exposed or ground, they quickly lose their flavor. However, high-quality ground
cardamom is often more readily (and cheaply) available, and is an acceptable substitute. For recipes
requiring whole cardamom pods, a generally accepted equivalent is 10 pods equals 1½ teaspoons of
ground cardamom.
Mustard
The condiment mustard seed is available today in three forms powdered dry mustard, known also as
"mustards flour" or "ground mustards" is made by grinding the seeds finely and then removing the
hulls by means of a multiple milling screening, and sifting operation. If”hot" mustard is desired, the
pungency is increased by pressing the ground product to remove a portion of the fixed oil. Prepared
mustard, also known as "mustard paste" is a mixture of ground mustard seed, salt, vinegar, and spices.
This very popular preparation is used on hot dogs, sandwiches, cheeses, eggs, meats, and salad
dressings. The brilliant yellow color of prepared mustard in the United States is due to the addition of
ground Alleppey (India) turmeric in its manufacture. This mustard is packed in glass jars, while in
Europe it is generally packed in tubes like toothpaste. The whole seeds may be used in pickling or be
boiled with vegetables-cabbage and sauerkraut, for instance. Unlike most other aromatic spices,
powdered mustard has no aroma when dry. It must be moistened for about ten minutes to develop its
sharp, hot, and tangy flavor. When the powder is mixed with warm water, enzyme activity develops
the pungent principle. Once the moistened powdered mustard has developed its aroma, it should be
used within an hour or the flavor will gradually be lost. The mustard served in Chinese restaurants is
usually freshly prepared in this manner. If the mustard is to be kept for an extended period, it must be
acidified (as with lemon juice, vinegar, or wine) to arrest enzymatic activity and the mixture
refrigerated. Prepared mustard if acidified with vinegar, it retains its strength. Manufacturers
frequently urge the refrigeration of mustard products. When added to mayonnaise, curries, or salad
dressings, mustard tends to act as a preservative by retarding decomposition brought about by
bacteria.
Part of the chemical structure of a "tear gas" used in World War I is also a part of the structure of the
glycoside sinigrin-found in black mustard seeds-that is exceedingly irritating to the mucous
membranes, especially those of the eyes and nose. Excessive amounts caused inflammation to the
respiratory passages of soldiers in the trenches in France, leading to severe lung damage and, on
occasion, death. On the other hand, such substances, when used in minute and strictly controlled
amounts as in condimental mustard, stimulate the appetite by increasing the activity of the salivary
glands. White mustard seeds contain almost no volatile oil. Those of black mustard may yield, on
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steam and water distillation, from 0.25 to 1.25 % of the essential oil used in the food industry. The
seeds of both species yield about 25 to 35 % of fixed oils, obtained by expression in an oil press.
These fixed oils, by-products of the condiment industry in many countries, many be used in soap
making, for burning in lamps, and as lubricants. In addition to being grown for its seed. White
mustard may be grown as a salad plant, cover crop, and "green manure" (plowed in, when half grown,
to add organic matter to the soil). Black mustard is grown mostly for its seed. The use of mustard as a
medicine in Western countries has declined in recent years. It previously had been used for centuries
as a stimulant, a diuretic, an emetic, a rubefacient, and an all-round remedy (in plaster form) to relieve
rheumatism and arthritis. 3.3. Postharvest Handling of Fruits and Vegetables
Production practices
Production practices have a tremendous effect on the quality of fruits and vegetables at harvest and on
postharvest quality and shelf life. To start with, it is well known that some cultivars ship better and
have a longer shelf life than others have. In addition, environmental factors such as soil type,
temperature, frost, and rainy weather at harvest can have an adverse effect on storage life and quality.
For example, carrots grown on muck soils do not hold up as well in storage as carrots grown on
lighter, upland soils. Lettuce harvested during a period of rain does not ship well and product losses
are increased. Management practices can also affect postharvest quality. Produce that has been
stressed by too much or too little water, high rates of nitrogen, or mechanical injury (scrapes, bruises,
abrasions) is particularly susceptible to postharvest diseases. Mold and decay caused by Rhizoctonia,
is due to fruits lying on the ground, which could be alleviated when using mulch. Broccoli heads are
susceptible to postharvest rot caused by the bacteria Erwinia if nitrogen is applied as foliar feed a
grower should feed the soil, not the leaves. Beets and radishes are susceptible to soil-borne diseases
when the soil temperature reaches 80º F; symptoms are black spots on these root crops. Food safety
also begins in the field, thus it requires special concern, since a number of outbreaks of food borne
illnesses have been traced to contamination of produce in the field. Common-sense prevention
measures include a number of do nots:
•
•
•
•
•
•
Do not apply raw dairy or chicken manure or slurries to a field where a vegetable crop such as leafy lettuce
is growing;
Do not apply manure to an area immediately adjacent to a field nearing harvest maturity;
Do not forget to clean equipment that has been used to apply manure to one field before moving it to
another field in production;
Do not irrigate with water from a farm pond used by livestock;
Do not harvest fruit from the orchard floor for human consumption as whole fruit or non-pasteurized juices,
especially if manure has been spread or animals allowed to graze; and
Do not accumulate harvested product in areas where birds roost.
A grower should constantly evaluate water used for irrigation, and compost all animal manures before
applying them to fields. There are good sources of information on growing practices that would
promote postharvest quality. Consult textbooks, Extension publications, and trade journals, and
become involved with grower organizations to find out more.
Harvesting
Maturity index for fruits and vegetables
•
•
•
Skin color: this factor is commonly applied to fruits, since skin color changes as fruit ripens or matures;
Optical methods: Light transmission properties can be used to measure the degree of maturity of fruits;
Shape: The shape of fruit can change during maturation and can be used as a characteristic to determine
harvest maturity;
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•
•
•
•
•
•
•
•
•
•
•
•
•
Size: Changes in the size of a crop while growing are frequently used to determine the time of harvest;
Aroma: Most fruits synthesize volatile chemicals as they ripen;
Fruit opening: Some fruits may develop toxic compounds during ripening, such as ackee tree fruit, which
contains toxic levels of hypoglycine;
Leaf changes: Leaf quality often determines when fruits and vegetables should be harvested;
Abscission: As part of the natural development of a fruit an abscission layer is formed in the pedicel;
Firmness: A fruit may change in texture during maturation, especially during ripening when it may
become rapidly softer;
Juice content: The juice content of many fruits increases as the fruit matures on the tree;
Oil content and dry matter percentage: Oil content can be used to determine the maturity of fruits,
such as avocados;
Moisture content: During the development of avocado fruit the oil content increases and moisture
content rapidly decreases;
Sugars: In climacteric fruits, carbohydrates accumulate during maturation in the form of starch. As the
fruit ripens, starch is broken down into sugar;
Starch content: Measurement of starch content is a reliable technique used to determine maturity in pear
cultivars;
Acidity: In many fruits, the acidity changes during maturation and ripening, and in the case of citrus and
other fruits, acidity reduces progressively as the fruit matures on the tree; and
Specific gravity: Specific gravity is the relative gravity, or weight of solids or liquids, compared to pure
distilled water at 62°F (16.7°C), which is considered unity.
Methods of harvesting
The goals of harvesting are to gather a commodity from the field at the proper level of maturity, with
a minimum of damage and loss, as rapidly as possible, and at a minimum cost. Today, as in the past,
these goals are best achieved through hand harvest in most fruit and vegetables.
Hand harvest
Primary advantages
•
•
•
•
Humans can accurately select for maturity, allowing accurate grading and multiple harvest;
Humans can handle fruit with a minimum of damage;
Rate of harvest can be easily increased by hiring more workers; and
Hand harvest requires a minimum of capital investment (although some fanners provide housing for their
employees)
The main problems with hand harvest are centered on labor management. Labor supply is a problem
for farmers who cannot offer a long employment season. Labor strikes during the harvest period can
be very costly. In recent years, there has been a significant increase in costs associated with
complying with government labor regulations. In spite of these problems, quality is such an important
aspect in successful marketing of fresh market commodities that hand harvest is still the dominant
method of harvest. Effective use of hand labor requires very careful management. New employees
must be trained to harvest the fruit quality needed at an acceptable rate. Employees must know what
level of performance is expected of them, and be encouraged and trained to reach that level. Benefits
such as paid vacations, insurance, and so on, will help ensure a return of employees who have already
been trained. With some commodities, machines have been used to aid hand harvest. Belt conveyors
are used in some vegetable crops such as lettuce and melons to move a harvested commodity to a
central loading or in-field handling device. Scoops with rods protruding from the end of the scoop are
used by workers to comb through some berry crops. Platforms or moveable worker positioners have
been used in place of ladders in crops such as dates, papayas, and bananas. Lights have been used to a
limited extent for night harvest of melons in California. This allows harvest when outside
temperatures are cool, which is easier on workers and can improve melon quality. Numerous other
mechanical aids have been tried, but they often do not increase productivity enough to warrant their
expense.
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Mechanical harvest
Main advantages of mechanical equipment
•
•
•
Potential of rapid harvest;
Improved conditions for workers; and
Reduced problems associated with hiring and managing hand labor
Effective use of mechanical harvesting equipment requires many skills not associated with hand
harvest. The equipment must be operated by dependable, well-trained people. Improper operation of
the equipment results in very costly damage to the expensive machinery and quickly damages a lot of
commodity. The equipment must be regularly maintained and emergency maintenance must be
available. The commodity must be grown to accept mechanical harvest. For example, trees must be
pruned for strength and minimize fruit damage caused by fruit falling through the tree canopy.
Maximum and uniform stand establishment is necessary for vegetable crops. In addition, cropping
patterns must be set up to utilize the expensive equipment as long as possible in order to pay for the
high capital investment. This can severely limit the production choices of some farmers. However,
mechanical harvest is not presently used for most fresh market crops because machines are rarely
capable of selective harvest, they tend to damage the commodity, and they are expensive. Mechanical
harvest can be used with commodities that can be harvested at one time and are not sensitive to
mechanical injury (roots, tubers, and nuts). Rapid processing after harvest will minimize the effects of
mechanical injury. Mechanical harvesting of crops now hand harvested will probably require breeding
new varieties that are more suited to mechanical harvest. This is a lengthy process and has been done
only for a very few commodities.
Mechanical harvest problems
•
•
•
•
Damage to perennial crops, for example, damage to bark from a tree shaker;
Lack of processing and handling capacity to handle the high rate of harvest;
Technological obsolescence before equipment is paid for; and
Social impacts of lower labor requirements
Harvesting container and tools
Harvesting containers must be easy to handle for workers picking fruits and vegetables in the field.
Many crops are harvested into bags. Harvesting bags with shoulder or waist slings can be used for
fruits with firm skins, like citrus fruits and avocados. These containers are made from a variety of
materials such as paper, polyethylene film, sisal, hessian, or woven polyethylene and are relatively
cheap but give little protection to the crop against handling and transport damage. Sacks are
commonly used for crops such as potatoes, onions, cassava, and pumpkins. Other types of field
harvest containers include baskets, buckets, carts, and plastic crates. For high-risk products, woven
baskets and sacks are not recommended because of the risk of contamination. Depending on the type
of fruit or vegetable, several devices are employed to harvest produce. Commonly used tools for fruit
and vegetable harvesting are secateurs or knives, and hand held or pole mounted picking shears.
When fruits or vegetables are difficult to catch, such as mangoes or avocados, a cushioning material is
placed around the tree to prevent damage to the fruit when dropping from high trees. Harvesting bags
with shoulder or waist slings can be used for fruits with firm skins, like citrus and avocados. They are
easy to carry and leave both hands free. The contents of the bag are emptied through the bottom into a
field container without tipping the bag. Plastic buckets are suitable containers for harvesting fruits that
are easily crushed, such as tomatoes. These containers should be smooth without any sharp edges that
could damage the produce. Commercial growers use bulk bins with a capacity of 250-500 kg, in
which crops such as apples and cabbages are placed, and sent to large-scale packinghouses for
selection, grading, and packing. 191
Harvest handling and transport to packaging house
Quality cannot be improved after harvest, only maintained; therefore, it is important to harvest fruits,
vegetables, and flowers at the proper stage and size and at peak quality. Immature or over mature
produce may not last as long in storage as that picked at proper maturity. Cooperative Extension
Service publications are an excellent source of information on harvest maturity indicators for
vegetables and fruits. Harvest should be completed during the coolest time of the day, which is
usually in the early morning, and produce should be kept shaded in the field. Handle produce gently.
Crops destined for storage should be as free as possible from skin breaks, bruises, spots, rots, decay,
and other deterioration. Bruises and other mechanical damage not only affect appearance, but provide
entrance to decay organisms as well. Postharvest rots are more prevalent in fruits and vegetables that
are bruised or otherwise damaged. Mechanical damage also increases moisture loss. The rate of
moisture loss may be increased by as much as 400 percent by a single bad bruise on an apple, and
skinned potatoes may lose three to four times as much weight as non-skinned potatoes. Damage can
be prevented by training harvest labor to handle the crop gently; harvesting at proper maturity;
harvesting dry whenever possible; handling each fruit or vegetable no more than necessary (field pack
if possible); installing padding inside bulk bins; and avoiding over- or under-packing of containers.
Packing in the field and transport to packinghouse can be effected by:
•
•
•
•
Polyethylene bags: Clear polyethylene bags are used to pack banana bunches in the field, which are then
transported to the packinghouse by means of mechanical cableways running through the banana plantation;
Plastic field boxes: These types of boxes are usually made of polyvinyl chloride, polypropylene, or
polyethylene;
Wooden field boxes: These boxes are made of thin pieces of wood bound together with wire; and
Bulk bins: Bulk bins of 200-500 kg capacity are used for harvesting fresh fruits and vegetables.
Preliminary postharvest operations
Washing and sanitation
Sanitation is of great concern to produce handlers, not only to protect produce against postharvest
diseases, but also to protect consumers from food-borne illnesses. E. coli 0157:H7, Salmonella,
Chryptosporidium, Hepatitis, and Cyclospera are among the disease-causing organisms that have
been transferred via fresh fruits and vegetables.Use of a disinfectant in wash water can help to prevent
both postharvest diseases and food-borne illnesses.
Chlorine in the form of a sodium hypochlorite solution or as a dry, powdered calcium hypochlorite
can be used in hydro-cooling or wash water as a disinfectant. Some pathogens such as
Chryptosporidium, however, are very resistant to chlorine, and even sensitive ones such as Salmonella
and E. coli may be located in inaccessible sites on the plant surface. For the majority of vegetables,
chlorine in wash water should be maintained in the range of 75–150 ppm (parts per million.) The
antimicrobial form, hypochlorous acid (Table 3.15. , is most available in water with a neutral pH (6.5
to 7.5).
Table 3.15. Amounts of hypochlorite to add to clear, clean water for disinfestations
Sodium hypochlorite
(5.25%)
Sodium hypochlorite
(12.7%)
Target ppm
50
75
100
125
150
50
75
100
125
150
Ounces/5 gallons
0.55
0.8
1.1
1.4
1.7
0.12
0.17
0.23
0.29
0.35
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Cup/50 gallons
0.50
0.75
1.00
1.25
1.50
0.10
0.15
0.20
0.25
0.30
Curing of roots, tubers, and bulb crops
Roots, tubers and bulbs can be cured if treated as shown in Table 3.16.
Table 3.16. Conditions for curing roots and tubers
Commodity
Potato
Sweet potato
Yams
Cassava
Temperature
(°C)
15-20
30-32
32-40
30-40
Relative humidity
(%)
90-95
85-90
90-100
90-95
Storage time
(days)
5-10
4-7
1-4
2-5
Operations prior to packaging
Fruits and vegetables are subjected to preliminary treatments designed to improve appearance and
maintain quality. These preparatory treatments include cleaning, disinfection, waxing, and adding of
color; some includes brand name stamping on individual fruits.
Cleaning: Most produce receives various chemical treatments such as spraying of insecticides and
pesticides in the field. Most of these chemicals are poisonous to humans, even in small
concentrations. Therefore, all traces of chemicals must be removed from produce before packing. Disinfection: After washing fruits and vegetables, disinfectant agents are added to the soaking tank
to avoid propagation of diseases among consecutive batches of produce.
Artificial waxing: Artificial wax is applied to produce to replace the natural wax lost during
washing of fruits or vegetables. This adds a bright sheen to the product. The function of artificial
waxing of produce is summarized below:
•
•
•
•
•
•
•
Provides a protective coating over entire surface;
Seals small cracks and dents in the rind or skin;
Seals off stem scars or base of petiole;
Reduces moisture loss;
Permits natural respiration;
Extends shelf life; and
Enhances sales appeal.
Brand name application: Some distributors use ink or stickers to stamp a brand name or logo on
each individual fruit. Ink is not permissible in some countries, but stickers are acceptable. Automatic
machines for dispensing and applying pressure sensitive paper stickers are readily available. The
advantage of stickers is that they can be easily peeled off.
Blanching: Blanching is a mild and short heat treatment (45-70C), used only on plant material as
vegetables and fruit (Table 3.17). The main purpose of blanching is the inactivation of oxidative
enzymes, but is also beneficial for packaging and processing of fruit and vegetables. Blanching, that
is, the exposure of the fruit and vegetables to mild temperatures for a few minutes is a critical control
operation in the processing of shelf-stable fruits. In traditional preservation methods, the main
function of this heat treatment is to destroy the enzymes that could deteriorate vegetables and fruits.
However, in these minimal processing techniques, blanching has another important role: to reduce the
initial microbial load by inactivating heat sensitive microorganisms. The temperatures used are lethal
for yeasts, most moulds, and aerobic microorganisms. Thus, blanching has been found to reduce the
microbial load from 60% to 99%. In addition, this heat treatment has a sensitizing effect on the
survivors, which would be less resistant to the stresses imposed by aw and pH reduction and by the
presence of sorbate and sulphites or other antimicrobials.
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Table 3.17. Blanching parameters for some vegetables
Vegetables
Peas
Green beans
Cauliflower
Carrots
Peppers
Temperature (°C)
85-90
90-95
Boiling
90
90
Time (min.)
2-7
2-5
2
3-5
3
Humectants: Increasing the concentration of dissolved compounds or solutes (namely
"humectants") decreases the water activity. The choice of the humectant depends on several factors,
such as, its water activity lowering capacity, cost, solubility, and the organoleptic characteristics of
the final product. The kind and concentration of humectant greatly affects the water and solute
exchanges during osmosis and so the characteristics of final product. Low molar mass saccharides
such as glucose, fructose, and sorbitol favor the sugar uptake due to the easy penetration of the
molecules; thus, solid enrichment instead of dehydration is the main effect of the process. On the
contrary, high molar mass solutes favor water loss instead of solid gain, resulting in a product with
low solute content.
Antimicrobials: Most common antimicrobials used in intermediate moisture fruit products and
ambient-stable high moisture fruit products are sorbic and benzoic acids and sulphite compounds.
They are primarily used to inhibit the growth of yeasts and moulds. The action of these preservatives
is very pH dependent, being more active against microorganisms in acid foods. In particular, the
antimicrobial effect of the acids is due partly to their influence on the pH of the food and partly to the
specific effect of the acid itself attributed mainly to the undissociated form of the acid. This permeates
the cell membrane, collaborating to the influx of protons.
Acidulants: pH is one of the most important hurdles in intermediate moisture fruit products and
ambient-stable high moisture fruit products since it determines the type of organisms that can
proliferate and their rate of growth, the activity of the preservatives and the stability of many
vitamins. In general, the pH of the preserved fruit must be as low as palatability permits. But
fortunately fruits can tolerate significant reductions of pH without flavor impairment. Sorting
•
•
•
•
•
•
Electronic sorting;
Hand sorting;
Comfortable Sorting Environment;
Lighting;
Fruit flow; and
Sorting accuracy
Sorting is necessary to remove blemished and damaged fruit and vegetables and to grade fruit
according to market specifications. Electronic sorting equipment is increasingly being used as an
alternative. Electronic sorting equipment should be positioned at the start of the packing line to
remove unpackable fruit prior to fungicide treatment and waxing. This reduces the size and cost of the
rest of the packing machinery.
Electronic sorting
A color video scanner feeds information to a computer to determine if each fruit is packable or not.
Electronic sorting equipment can be programmed to accept or reject different degrees of blemish.
Some disorders such as creasing are difficult to grade electronically and hand sorting is still required
as a final check on the fruit. Labor costs for sorting can be reduced as much as 50% allowing time for
more accurate assessment of fruit quality by hand sorters. Surveys have shown that blemish, red scale,
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creasing, rind texture and on Valencia oranges, color, account for most of the fruit rejected during
sorting.
Hand sorting
Hand sorting efficiency can be improved by ensuring staff are comfortable, have good lighting and
are trained in regard to sorting criteria.
Comfortable sorting environment
Sorting inside an enclosed air-conditioned room can protect sorters from noise, cold and heat and
ensure that mould spores released by the sorting process are not distributed throughout the packing
shed. Re-circulated water in fluming can be employed to take moldy citrus fruits outside of the shed
to minimize risk of infection from mould.
Lighting
Good lighting is essential. Cool white fluorescent lighting producing 178 foot candles or 1900 Lux at
the fruit surface should be suitable.
Fruit flow
The flow of fruit should be broken up into lanes no wider than 30cm and preferably the roller
direction of turn should be reversed so that fruit is rolling towards the sorter. One sorter should be
responsible for each lane of fruit.
Sorting accuracy
Sorting accuracy can be improved by ensuring that sorters have access to photographic guides
illustrating blemishes, defects and disorders. Sorters should be regularly updated on market
specifications. Electronic sorting equipment can improve sorting efficiency by eliminating out of
grade fruit and reducing the quantity of good fruit inadvertently culled out by sorters.
Sizing
•
•
Transverse roller sizer; and
Weight sizers
Citrus fruit needs to be sized accurately to enable packages to be correctly filled and attractively
presented in the market place. Citrus fruit can be sized mechanically, with electronic optical sizers or
weight sizing equipment. Electronic volumetric sizing is more accurate and less damaging to the fruit
than mechanical sizing. Mechanical sizing of citrus is carried out with belt and roller sizing or
expanding roller equipment. Properly set up belt and roller sizing can be quite accurate if not overloaded but some skill is needed to re-set the size for various shapes of fruit. Lemons require slow belt
speeds whereas flat fruit such as some mandarins need faster belt speeds. If roller speeds are too fast
in relation to belt speed, fruit kicks out, or if roller speeds are too slow in relation to belt speeds, the
fruit wedges or drags. Lemons and mandarins are best graded with electronic optical sizing
equipment.
Transverse roller sizer
Various types of expanding roller sizers are available. Some have variable speed rollers which can
"spin up" flat fruit such as mandarins which otherwise would size inaccurately on a slowly rotating
roller. Bearing wear and bent rollers are sometimes a problem with expanding roller sizers.
Weight sizers
These are not recommended for sizing fruit intended for pattern packing. Variation in fruit density is
too great resulting in variable pack heights and poor presentation.
Packaging fruits and vegetables
Modern packaging must comply with the following requirements:
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•
•
•
•
•
•
•
•
•
•
The package must have sufficient mechanical strength to protect the contents during handling, transport,
and stacking;
The packaging material must be free of chemical substances that could transfer to the produce and become
toxic to man;
The package must meet handling and marketing requirements in terms of weight, size, and shape;
The package should allow rapid cooling of the contents. Furthermore, the permeability of plastic films to
respiratory gases could also be important;
Mechanical strength of the package should be largely unaffected by moisture content (when wet) or high
humidity conditions;
The security of the package or ease of opening and closing might be important in some marketing
situations;
The package must either exclude light or be transparent;
The package should be appropriate for retail presentations;
The package should be designed for ease of disposal, re-use, or recycling; and
Cost of the package in relation to value and the extent of contents protection required should be as low as
possible.
Classification of packaging
Packages can be classified as follows:
•
•
•
•
•
•
Flexible sacks; made of plastic jute, such as bags (small sacks) and nets (made of open mesh);
Wooden crates;
Cartons (fiberboard boxes);
Plastic crates;
Pallet boxes and shipping containers; and
Baskets made of woven strips of leaves, bamboo, plastic, etc.
Uses for above packages
Nets are only suitable for hard produce such as coconuts and root crops (potatoes, onions, yams).
Wooden crates are typically wire bound crates used for citrus fruits and potatoes, or wooden field
crates used for softer produce like tomatoes. Wooden crates are resistant to weather and more efficient
for large fruits, such as watermelons and other melons, and generally have good ventilation.
Disadvantages are that rough surfaces and splinters can cause damage to the produce, they can retain
undesirable odors when painted, and raw wood can easily become contaminated with moulds.
Fiberboard boxes are used for tomato, cucumber, and ginger transport. They are easy to handle,
lightweight, come in different sizes, and come in a variety of colors that can make produce more
attractive to consumers. They have some disadvantages, such as the effect of high humidity, which
can weaken the box; neither are they waterproof, so wet products would need to be dried before
packaging. These boxes are often of lower strength compared to wooden or plastic crates, although
multiple thickness trays are very widely used. They can come flat packed with ventilation holes and
grab handles, making a cheap attractive alternative that is very popular. Care should be taken that
holes on the surface (top and sides) of the box allow adequate ventilation for the produce and prevent
heat generation, which can cause rapid product deterioration.
Plastic crates are expensive but last longer than wooden or carton crates. They are easy to clean
due to their smooth surface and are hard in strength, giving protection to products. Plastic crates can
be used many times, reducing the cost of transport. They are available in different sizes and colors and
are resistant to adverse weather conditions. However, plastic crates can damage some soft produce
due to their hard surfaces, thus liners are recommended when using such crates.
Pallet boxes are very efficient for transporting produce from the field to the packinghouse or for
handling produce in the packinghouse. Pallet boxes have a standard floor size (1200 × 1000 mm) and
depending on the commodity have standard heights. Advantages of the pallet box are that it reduces
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the labor and cost of loading, filling, and unloading; reduces space for storage; and increases speed of
mechanical harvest. The major disadvantage is that the return volume of most pallet boxes is the same
as the full load. Higher investment is also required for the forklift truck, trailer, and handling systems
to empty the boxes. They are not affordable to small producers because of high, initial capital
investment.
Nested packaging
Dry leaves or straw can be used to package fruits and vegetable for short term storage until products
reach market and sold. The typical example is packaging of banana in dry plantain leaves during
ripening in storage and transportation.
Flexible film and bags packaging
There are several different types of flexible film for packaging of fruits and vegetables such as
polyethylene, polypropylene, polyvinylchloride etc. This plastic film exists in high or low density
depending on the respiratory characteristics of fruits and vegetables.
Modified atmosphere packaging
Modified atmosphere packaging (MAP) refers to packaging of perishable products in an atmosphere,
which has been modified so that its composition is other than that of air. Whereas controlled
atmosphere storage involves maintaining a fixed concentration of gases surrounding the product by
careful monitoring and addition of gases, the gaseous composition of fresh MAP foods is constantly
changing due to chemical reactions and microbial activity. Gas exchange between the pack headspace
and the external environment may also occur because of permeation across the package material.
Packing foods in a modified atmosphere can offer extended shelf life and improved product
presentation in a convenient container, making the product more attractive to the retail customer.
However, MAP cannot improve the quality of a poor quality food product. It is therefore essential that
the food be of the highest quality prior to packing in order to optimize the benefits of modifying the
pack atmosphere. Good hygiene practices and temperature control throughout the chill-chain for
perishable products are required to maintain the quality benefits and extended shelf life of MAP
foods.
Gases used in modified atmosphere packaging: The three main gases used in modified
atmosphere packaging are O2, CO2, and N2. The choice of gas is very dependent upon the food
product being packed. Used singly or in combination, these gases are commonly used to balance safe
shelf life extension with optimal organoleptic properties of the food. Noble or 'inert' gases such as
argon are in commercial use for products such as coffee and snack products; however, the literature
on their application and benefits is limited. Experimental use of carbon monoxide (CO) and sulphur
dioxide (SO2) has also been reported.
Carbon dioxide: Carbon dioxide is a colorless gas with a slight pungent odor at very high
concentrations. It is an asphyxiant and slightly corrosive in the presence of moisture. CO2 dissolves
readily in water (1.57 g/kg @ at 100 kPa, 20° C) to produce carbonic acid (H2CO3) that increases the
acidity of the solution and reduces the pH. This gas is also soluble in lipids and some other organic
compounds. The solubility of CO2 increases with decreasing temperature. For this reason, the
antimicrobial activity of CO2 is markedly greater at temperatures below 10° C than at 15° C or higher.
This has significant implications for MAP of foods. The high solubility of CO2 can result in pack
collapse due the reduction of headspace volume. In some MAP applications, pack collapse is favored,
for example in flow wrapped cheese for retail sale.
Oxygen: Oxygen is a colorless, odorless gas that is highly reactive and supports combustion. It has a
low solubility in water (0.040 g/kg at 100 kPa, 20° C). Oxygen promotes several types of deteriorative
reactions in foods including fat oxidation, browning reactions and pigment oxidation. Most of the
common spoilage bacteria and fungi require oxygen for growth. Therefore, to increase shelf life of
foods the pack atmosphere should contain a low concentration of residual oxygen. It should be noted
197
that in some foods a low concentrations of oxygen can result in quality and safety problems (for
example unfavorable color changes in red meat pigments, senescence in fruit and vegetables, growth
of food poisoning bacteria) and this must be taken into account when selecting the gaseous
composition for a packaged food. Nitrogen: Nitrogen is a relatively un-reactive gas with no odor, taste, or color. It has a lower density
than air, non-flammable and has a low solubility in water (0.018 g/kg at 100 kPa, 20° C) and other
food constituents. Nitrogen does not support the growth of aerobic microbes and therefore inhibits the
growth aerobic spoilage but does not prevent the growth of anaerobic bacteria. The low solubility of
nitrogen in foods can be used to prevent pack collapse by including sufficient N2 in the gas mix to
balance the volume decrease due to CO2 going into solution.
Carbon monoxide: Carbon monoxide is a colorless, tasteless, and odorless gas that is highly
reactive and very flammable. It has a low solubility in water but is relatively soluble in some organic
solvents.
Packaging with small unit: For retailer market smaller unit of half, 1kg-15 kg capacity packaging
is more preferable.
Controlling of biodeterioration factors
Postharvest fruit and vegetable disease
Stored produce is subject to a variety of rots and decay caused by fungi or bacteria. These organisms
may cause soft spots or light brown lesions on fruits and vegetables. Fungal growth, in a variety of
colors, may also be apparent on the surface of infected produce. In time, the entire fruit or vegetable
can become dry and mummified, or, under moist conditions, a soft, wet mass.
Postharvest diseases may start before or after harvesting. Plants or fruits infected in the field may not
develop symptoms until stored. Once in storage, infections continue to develop on the fruits and
vegetables. Wounds, cuts, or bruises caused during harvesting are common entry points for bacteria
and fungi. Penetration can also occur during storage through natural openings, such as lenticels, or
directly through the cuticle and epidermis. Spread of the infection usually requires the presence of
warm temperatures and high moisture, although some storage rots can continue to develop at low
temperatures. Penicillium, a fungus which causes blue and green mold on fruits, can continue to grow
slowly even at temperatures near freezing. Once produce is infected, the disease can spread to healthy
produce by direct contact. Insects can also be involved in spreading disease. Fruit flies, attracted to
fruits and vegetables infected with "sour rot" carry spores of the fungus Geotrichum from infected
produce to healthy produce.
Postharvest physiological disorders
Postharvest physiological disorders refer to the breakdown of tissue that is not caused by invasion of
pathogens. They may develop in response to an adverse environmental condition or a nutritional
deficiency during growth and development
Low temperature disorders
Storage produce at low temperature is beneficial, because the rate of respiration and metabolism is
reduced. However, low storage temperatures do not suppress all aspects of metabolism to the same
extent (Table 3.18). Some reactions are sensitive to low temperatures and cease completely below a
critical temperature. Decreasing the temperature does not reduce the activity of other systems to the
same extent as it does respiration. The overall effect is the creation of a metabolic imbalance and if it
becomes serious enough, to result in an essential substrate not being provided, or toxic products being
accumulated, the cells will cease to function properly and will eventually lose their integrity and
structure. These collapsed cells manifest themselves as areas of brown tissue in apples. Metabolic
disturbances occurring at reduced temperatures are generally divided into two main groups: those due
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to chilling injuries and those due to physiological disorders. In addition, early maturing varieties have
shorter storage life and are prone to chilling injuries than late maturing varieties.
Table 3.18. Fruits and vegetables susceptible to chilling injury when stored at moderately low nonfreezing temperatures
Produce
Apples, some cultivars
Avocados
Bananas
Beans (snap)
Cucumbers
Eggplants
Grapefruit
Lemons
Melons
Mangoes
Oranges (CA, AZ)
Papayas
Pineapples
Pumpkins
Sweet potatoes
Tomatoes
(o C)
2.2—3.3
4.4—7.2
11.7—13.3
7.2
7.2
7.2
10.0
12.8
7.2
10.0—12.8
3.3
7.2
7.2—10
7.2—10
10
7.2—12.8
Sign
Internal browning, brown core, soft scald, soggy breakdown
Graying brown discoloration of flesh
Dull skin color, browning of flesh, failure to ripen
Pitting and russeting
Pitting and water soaked area
Surface scald
Pitting, scald, watery breakdown
Pitting, membranous stain, red blotch
Pitting
Grayish scald-like discoloration of skin, unever ripening
Pitting, brown stain
Pitting, failure to ripen, off flavor, decay
Dull green when ripened
Decay
Decay, pitting
Water soaked areas, poor color development immature
green tomatoes
Mineral deficiency disorders
Plants require a balanced mineral intake for proper development, so a deficiency in any essential
mineral will lead to maldevelopment of the plant as a whole. It can be said that the condition is a
physiological disorder if the fruiting organ or actual "vegetable" portions is affected rather than the
whole plant. Calcium has been associated with more deficiency disorders than other minerals (Table
3.19). The application of calcium salts can increase firmness, acidity, and solids and completely
prevent the occurrence of disorders such as blossom-end rot in the tomato; but with other disorders,
such as bitter pit, only partial control is obtained. The role of calcium may be physiological, since it
suppresses respiration and several other metabolic sequences in plant tissues such as breakdown.
Calcium is associated with peptic substances in the middle lamala and membranes and many prevent
disorders merely by strengthening the structural components of the cell without alleviating the
original cause of cell collapse. The toxic compounds that lead to cell collapse would need to be
present in a greater concentration before cell disintegration, and before browning symptoms manifest.
Table 3.19. Calcium-related disorders of fruits and vegetables
Produce
Apple
Avocado
Bean
Chinese cabbage
Carrot
Mango
Pepper
Potato
Tomato
Watermelon
Disorder
Bitter pit, lenticel blotch, cork spot, lenticel breakdown, cracking, low
temperature breakdown, internal breakdown, senescent breakdown,
Jonathan spot, water core
End spot
Hypocotyi necrosis
internal tipbum
Cavity spot, cracking
Soft nose
Blossom-end rot
Sprout failure
Blossom-end rot, black seed, cracking
Blossom-end rot
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Principles of fruit and vegetables storage
Fruit and vegetables contain high moisture content and nutrients. Due to this, fresh produces under go
faster changes in terms of their physiology, biochemistry, microbiology during ripening, storage, and
transportation. Resulting from these characteristics the respiration rate of fruits and vegetables s high
if stored at high temperature. Therefore, the basic principles of fruits and vegetables storage are to
reduce storage temperature, increase relative humidity, and carbon dioxide concentration, and hence
reduce respiration rate, which leads to shelf life improvement. Technologies that enable to reduce
level of oxygen such as modified atmosphere packaging, controlled atmosphere storage, and cold
storage are very important in fruits and vegetables preservation. Temperature
Temperature is the single most important factor in maintaining quality after harvest.
Refrigerated storage retards the following elements of deterioration in perishable crops:
•
•
•
•
•
aging due to ripening, softening, and textural and color changes;
undesirable metabolic changes and respiratory heat production;
moisture loss and the wilting that results;
spoilage due to invasion by bacteria, fungi, and yeasts; and
undesirable growth, such as sprouting of potatoes.
One of the most important functions of refrigeration is to control the crop's respiration rate.
Respiration generates heat as sugars, fats, and proteins in the cells of the crop are oxidized. The loss
of these stored food reserves through respiration means decreased food value, loss of flavor, loss of
salable weight, and more rapid deterioration. The respiration rate of a product strongly determines its
transit and postharvest life. The higher the storage temperature, the higher the respiration rate will be.
For refrigeration to be effective in postponing deterioration, it is important that the temperature in
cold storage rooms be kept as constant as possible (Table 3.20). Exposure to alternating cold and
warm temperatures may result in moisture accumulation on the surface of produce (sweating), which
may hasten decay. Storage rooms should be well insulated and adequately refrigerated, and should
allow air circulation to prevent temperature variation. Be sure that thermometers, thermostats, and
manual temperature controls are of high quality, and check them periodically for accuracy.
Table 3.20. Storage conditions of fruits and vegetables
sensitive
Apples
Apricots
Asparagus
Avocados
Bananas
Beans, snap
Beans, lima
Beets, root
Blackberries
Blueberries
Broccoli
Brussels sprouts
Cabbage
Cantaloupe
Carrots, topped
Storage conditions for vegetables and fruits
Temperature % Relative humidity
Precooling
Storage Life Days
30-40
90-95
R,F,H
90–240
32
90-95
R,H
7–14
32-35
95-100
H,I
14–21
40-55
85-90
14–28
56-58
90-95
7–28
40-45
95
R,F,H
10–14
37-41
95
7–10
32
98-100
R
90–150
31-32
90-95
R,F
2–3
31-32
90-95
R,F
10–18
32
95-100
I,F,H
10–14
32
95-100
H,V,I
21–35
32
98-100
R,F
90–180
36-41
95
H,F
10–14
32
98-100
I,R
28–180
200
Ethylene
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Table 3.20. Cont.
Storage conditions for vegetables and fruits
sensitive
Temperature
% Relative humidity
Precooling
Storage Life Days
Ethylene
Cherries, sweet
30-31
90-95
H,F
14–21
Corn, sweet
32
95-98
H,I,V
4–6
Cranberries
36-40
90-95
60–120
Cucumbers
50-55
95
F,H
10–14
Y
Eggplant
46-54
90-95
R,F
10–14
Y
Endive
32
90-95
H,I
14–21
Y
Garlic
32-34
65-75
N
90–210
Grapefruit
50-60
85-90
28–42
Grapes
32
85
F
56–180
Kiwifruit
32
95-100
28–84
Y
Leeks
32
95-100
H,I
60–90
Y
Lemons
50-55
85-90
30–180
Lettuce
32
85-90
H,I
14–21
Y
Limes
48-50
85-90
21–35
Mushrooms
32
95
12–17
Nectarines
31-32
95
F,H
14–18
Y
Okra
45-50
90-95
7–14
Onions, bulb
32
65-70
N
30–180
Onions, green
32
95-100
H,I
7–10
Oranges
32-48
85-90
21–56
Peaches
31-32
90-95
F,H
14–28
Y
Pears
32
90-95
F,R,H
60–90
Y
Peas, in pods
32
95-98
F,H,I
7–10
Y
Peppers, bell
40-55
90-95
R,F
12–18
Y
Peppers, hot
45-50
60-70
R,F
14–21
Y
Pineapple
45-55
85-90
14–36
Plums
32
90-95
F,H
14–28
Y
Potatoes, early
50-60
90
R,F
56–140
Potatoes, late
40-50
90
R,F
56–140
Y
Pumpkins
50-60
50-75
N
84–160
Raspberries
32
90-95
R,F
2–3
Y
Rutabagas
32
98-100
R
120–180
Spinach
32
95-100
H,I
10–14
Y
Squash, summer
41-50
95
R,F
7–14
Y
Squash, winter
50-55
50-70
N
84–150
Strawberries
32
90-95
R,F
5–10
Sweet potatoes
55-60
85-90
N
120–210
Y
Tangerines
40
90-95
14–28
Tomatos
62-68
90-95
R,F
7–28
Y
Turnips
32
95
R,H,V,I
120–150
Watermelon
50-60
90
N
14–21
F=forced–air cooling, H=hydrocooling, I=package icing, R=room cooling, V=vacuum cooling, N=no precooling needed
Pre-cooling
Pre-cooling is the first step in good temperature management. The field heat of a freshly harvested
crop heat the product holds from the sun and ambient temperature is usually high, thus, should be
removed as quickly as possible before shipping. Refrigerated trucks are not designed to cool fresh
commodities but only maintain the temperature of pre-cooled produce. Likewise, most refrigerated
201
storage rooms have neither the refrigeration capacity nor the air movement needed for rapid cooling.
Therefore, pre-cooling is generally a separate operation requiring special equipment and/or rooms.
Rapid pre-cooling to the product's lowest safe temperature is most critical for crops with inherently
high respiration rates. These include artichokes, brussels sprouts, cut flowers, green onions, snap
beans, asparagus, broccoli, mushrooms, peas, and sweet corn. Crops with low respiration rates include
nuts, apples, grapes, garlic, onions, potatoes (mature), and sweet potatoes. The following methods are
the most commonly used
Room cooling Produce is placed in an insulated room equipped with refrigeration units. This method can be used
with most commodities, but is slow compared with other options. A room used only to store
previously cooled produce requires a relatively small refrigeration unit. However, if it is used to cool
produce, a larger unit is needed. Containers should be stacked so that cold air can move around them,
and constructed so that it can move through them. Used refrigerated truck bodies make excellent
small cooling rooms.
Forced-air cooling
Fans are used in conjunction with a cooling room to pull cool air through packages of produce.
Although the cooling rate depends on the air temperature and the rate of airflow, this method is
usually 75–90 percent faster than room cooling. Fans should be equipped with a thermostat that
automatically shuts them off as soon as the desired product temperature is reached.
Hydro cooling
Dumping produce into cold water, or running cold water over produce, is an efficient way to remove
heat, and can serve as a means of cleaning at the same time. In addition, hydro cooling reduces water
loss and wilting. Use of a disinfectant in the water is recommended to reduce the spread of diseases.
Hydro cooling is not appropriate for berries, potatoes to be stored, sweet potatoes, bulb onions, garlic,
or other commodities that cannot tolerate wetting.
Top or liquid icing
Icing is particularly effective on dense products and palletized packages that are difficult to cool with
forced air. In top icing, crushed ice is added to the container over the top of the produce by hand or
machine (Table 3.21). For liquid icing, slurry of water and ice is injected into produce packages
through vents or handholds without removing the packages from pallets and opening their tops. Icing
methods work well with high-respiration commodities such as sweet corn and broccoli. One pound of
ice will cool about three pounds of produce from 85º F to 40º F.
Vacuum cooling
Produce is enclosed in a chamber in which a vacuum is created. As the vacuum pressure increases,
water within the plant evaporates and removes heat from the tissues. This system works best for leafy
crops, such as lettuce, which have a high surface-to-volume ratio. To reduce water loss, water is
sometimes sprayed on the produce prior to placing it in the chamber. This process is called hydrovac
cooling. The primary drawback to this method is the cost of the vacuum chamber system.
Chilling injury
Many vegetables and fruits store best at temperatures just above freezing, while others are injured by
low temperatures and should be stored best at 45 to 55 0F. Both time and temperature are involved in
chilling injury. Damage may occur in a short time if temperatures are considerably below the danger
threshold, but some crops can withstand temperatures a few degrees into the danger zone for a longer
time. The effects of chilling injury are cumulative in some crops. Low temperatures in transit, or even
in the field shortly before harvest, add to the total effects of chilling that might occur in storage. Crops
such as basil, cucumbers, eggplants, pumpkins, summer squash, okra, and sweet potatoes are highly
sensitive to chilling injury. Moderately sensitive crops are snap beans, muskmelons, peppers, winter
202
squash, tomatoes, and watermelons. These crops may look sound when removed from low
temperature storage, but after a few days of warmer temperatures, chilling symptoms become evident:
pitting or other skin blemishes, internal discoloration, or failure to ripen. Tomatoes, squash, and
peppers that have been over-chilled may be particularly susceptible to decay such as Alternaria rot.
Table 3.21. Products that can be iced and not
These products can be iced
Artichokes
Asparagus
Beets
Broccoli
Cantaloupes
Carrots
Cauliflower
Endive
Green Onions
Leafy Greens
Radishes
Spinach
Sweet Corn
Watermelon
These items are damaged
by direct contact with ice
Strawberries
Blueberries
Raspberries
Tomatoes
Squash
Green Beans
Cucumbers
Garlic
Okra
Bulb Onions
Romaine Lettuce
Herbs
Preventing moisture loss
While temperature is the primary concern in the storage of fruits and vegetables, relative humidity is
also important. The relative humidity of the storage unit directly influences water loss in produce.
Water loss can severely degrade quality for instance, wilted greens may require excessive trimming,
and grapes may shatter loose from clusters if their stems dry out. Water loss means salable weight loss
and reduced profit. Most fruit and vegetable crops retain better quality at high relative humidity (80 to
95 percent), but at this humidity, disease growth is encouraged. The cool temperatures in storage
rooms help to reduce disease growth, but sanitation and other preventative methods are also required.
Maintaining high relative humidity in storage is complicated by the fact that refrigeration removes
moisture. Humidification devices such as spinning disc aspirators may be used. Even buckets of water
will increase humidity as the fans blow air across the water's surface and increase evaporation.
Keeping the floor wet is helpful, though messy and potentially hazardous to two-legged creatures;
frequent cleansing with a weak chlorine solution will be needed to prevent harboring of disease
organisms in water and produce scraps on the floor. Crops that can tolerate direct contact with water
may be sprinkled to promote high relative humidity. When it comes to maintaining appropriate
humidity levels, "the biggest thing for small growers is going to be monitoring equipment. Humidity
is measured by an instrument called a hygrometer. Several companies offer small, low-priced
hygrometers suitable for small-scale producers.
Ethylene
Ethylene, a natural hormone produced by some fruits as they ripen, promotes additional ripening of
produce exposed to it. Damaged or diseased apples produce high levels of ethylene and stimulate the
other apples to ripen too quickly. As the fruits ripen, they become more susceptible to diseases.
Ethylene "producers" should not be stored with fruits, vegetables, or flowers that are sensitive to it.
The result could be loss of quality, reduced shelf life, and specific symptoms of injury. Some
examples of ethylene effects include:
•
•
•
russet spotting of lettuce along the midrib of the leaves;
loss of green color in snap beans;
increased toughness in turnips and asparagus spears;
203
•
•
•
•
•
•
•
•
•
bitterness in carrots and parsnips;
yellowing and abscission of leaves in broccoli, cabbage, Chinese cabbage, and cauliflower;
accelerated softening of cucumbers, acorn and summer squash;
softening and development of off-flavor in watermelons;
browning and discoloration in eggplant pulp and seed;
discoloration and off-flavor in sweet potatoes;
sprouting of potatoes;
increased ripening and softening of mature green tomatoes; and
Shattering of raspberries and blackberries.
Underground storage
Some vegetables can be left in situ conditions until the good price comes provided the soil is dry
during a short time of 1-3 months storage in the soil. On the other hand, some vegetables like potato
can be mixed with dry organic soil and stored in underground storage systems for some time enabling
shelf life extension.
Controlled atmosphere storage
Controlled atmosphere storage referees to conditions where concentration of oxygen, carbon dioxide
and other gases artificially applied and controlled during the storage period. The concentrations of
these gases are different for different fruits and vegetables. Therefore, the first step is identifying the
optimum gas concentration required by fruit or vegetable under consideration.
Cold storage for fruits and vegetables
Each fruit and vegetables require specific storage conditions, which are optimum for their safe
storage. The relative humidity and air temperature are known to be specific not only for a given crop
but for variety. During storage of fruits and vegetables in mechanically cold/refrigerated storage
system, the optimum conditions for a particular commodity have to be identified (see optimum
temperature and relative humidity table presented above). The cold storage reduces air temperature, in
some case increases the relative humidity, and hence reduces the respiration rate of fruits and
vegetables as well as reduced growth of microorganisms, which are otherwise responsible for the
occurrence of decay and rot. On the other hand, reduced temperature leads to slow biochemical and
chemical changes in fruits and vegetable that indirectly means reduced rate of ripening. This
phenomenon is required because it enables fruits and vegetables to be stored longer without
significant quality deterioration (Figures 4.29 and 4.30).
Low-cost evaporative cooling storage
Natural ventilation evaporative cooler
A ir outlet
Per forated
shelf
E vap orative coolin g pad
Fruit
A ir inlet
W ater tank
204
Forced ventilation evaporative cooler
Dry bulb temperature, °C
40
100
90
80
70
60
50
40
30
20
10
0
35
30
25
20
15
0
2
4
6
8
Relative humidity, %
Fig. 4.29. Effect of evaporative cooling on relative humidity and temperature during storage of fruits and vegetables
10
Time, h
Outside air temperature
Cooler relative humidity
Cooler air temperature
Outside relative humidity
Fig. 4.30 Changes in temperature and relative humidity inside and outside the evaporative cooler
Transportation, Distribution and Marketing
Transit temperature management
To be effective, a system needs forced-air delivery and air-return channel(s) large enough to enable
fans to operate at near-peak performance. Anything that interferes with this air circulation reduces air
volume output of the blowers (fans), thereby reducing the amount of circulating cold air for
temperature maintenance. A thick layer (8 to 16 in.) of top-ice over load prevents cold air from
penetrating the ice and cooling the load. In trailers with frame-front bulkheads, this results in only the
top product layer, in contact with the ice, being kept cool while product warming occurs in lower
layers in tight loads. Applying top-ice in windrowed pattern prevents this from occurring and provides
faster cooling. In trailers with solid-front return air bulkheads, top-ice causes a false, "already cold"
signal to be transmitted to the thermostat. This causes the refrigeration unit to go to the heating cycle,
which melts the top-ice and causes product warming.
Product compatibility
In mixed loads, certain product compatibility factors must be considered. These include following:
205
•
Temperature compatibility—Differences in temperatures needed for various products in a load must be
considered. For example, strawberries must be kept near 32°F (0°C) and should not be shipped with
summer squash, cucumbers, or tomatoes;
Ethylene production and sensitivity compatibility—Care must be taken not to ship commodities
that produce large amounts of ethylene (e.g., apples, pears, avocados, and certain muskmelons) with
commodities that are very sensitive to ethylene (broccoli, carrots, lettuce, kiwifruit, and most ornamentals).
The incidence of russet spotting on lettuce (caused by exposure to ethylene) is about three times greater in
mixed loads than in straight loads in truck shipments;
Product odor(s) compatibility—some products produce odors (e.g., onions and garlic) which can be
absorbed by other products, causing the latter to have an objectionable odor, and less market appeal; and
Moisture compatibility—some products benefit from package-ice or a high relative humidity in the
ambient atmosphere (e.g., leafy vegetables, sweet corn, and berries) while other commodities benefit from
intermediate humidity levels (e.g., garlic and dry onions). Humidity control is especially important during
long transit periods.
•
•
•
Marketing
Wholesalers
•
•
•
•
•
•
•
•
Chain store distribution centers servicing own stores;
Service wholesalers supply produce to independent and/or chain retail stores;
Car lot receivers divide and sell large quantities to retailers, brokers, jobbers, purveyors, and institutions,
and may service retail stores;
Commission merchants be car lot receivers who sell consigned shipments on a fixed percent commission
and may perform the same functions as car lot receivers, including servicing of retail stores;
Jobbers handle products from car lot receivers to small, independent retailers;
Mixers buy from other wholesalers, generally car lot receivers, and make up mixed loads of various
commodities for shipping on order to distant markets;
Purveyors service restaurants, institutions, and/or carriers and may also be processors of prepared foods;
and
Wholesale auctions sell certain commodities on a price-bid basis.
Retailers
•
•
•
Chain stores may belong to corporations, individuals (families), or to cooperatives they may be large or
small;
Independent stores and other outlets include neighborhood supermarkets, small ("Mom and Pop") retail
stores, green grocer stores that sell only produce and produce-related items, and produce carts; and
Direct marketing outlets include farmer's markets, roadside stands, "pick-your-own" operations, and "renta-tree" operations.
Problems of wholesalers and retailers
Wholesalers' problems
•
•
•
•
•
•
•
•
Produce warehouse management personnel need of more training in horticultural product-handling
requirements;
Non uniformity of produce quality;
Purchased or received commodities being often immature, overripe, or of mixed maturities requiring extra
handling, space, and time, thus causing marketing losses;
A need for quality control at both shipping points and at the wholesale level to be improved; and for better,
more objective communication of product quality;
Physical facilities used in many operations being inadequate for proper product handling, especially with
respect to temperature maintenance, sanitation, and ethylene concentrations in storage atmospheres;
Transportation problems, including product temperature management and physical damage to shipping
containers and products during transit;
Education programs in product handling being made available to wholesale handlers (wholesaler handling
practices can either compound or alleviate previous mishandling, maturity, or temperature-management
problems); and
Extra handling required for many products received on nonstandard-size pallets 206
Retailers' problems
•
•
•
•
•
•
•
•
Difficulty to obtain uniform-quality supplies of each commodity;
The lack of uniform maturity and ripeness with various commodities—especially common among
muskmelons, tomatoes, and some temperate fruits;
Inadequate quality control at the shipping point and at wholesale levels;
Knowledgeable personnel to be recruited and retained;
Inadequate physical facilities existing for temporary holding and displaying of produce under optimum
conditions;
Product-handling education programs for retail produce personnel lacking at wholesale and retail levels
(such programs could be provided or conducted by the company's own staff, produce consultants, produce
trade associations, commodity group representatives;
Improved communications among handlers in the various handling steps, primarily through trade
associations' programs, including educational activities aimed at food-service produce handlers; and
Expanded efforts by national produce associations in promoting the nutritional value of fresh produce and
in supporting studies on the effects of handling practices on maintenance of nutritional quality Postharvest handling of selected commodities
Onions
Maturity
Onions are ready for harvest when the necks are reasonably dry and the tops have fallen over. As
onions mature, their dry matter content and pungency increase, with a resulting increase in storage
potential. Therefore, farmers should get sufficient awareness concerning the maturity stage of onion
for proper harvesting and shelf life improvement. If onion bulb is harvested when the neck is closed
due to few surface layer skin then the possibility of moisture movement from the inside of the bulb as
well as contamination due to microbiological entrance are highly limited. The following photograph
shows a typical maturity stage for harvest and subsequent storage for relatively longer period.
Harvesting
Harvest onions when the weather is dry; harvesting after a rainfall, or when the humidity is high
increases susceptibility to post-harvest disease. At harvest, bulbs must be firm, with mature necks and
scales, and must be a good size. Like many types of temperate climate plants, onions have a period of
active growth followed by a period of dormancy. This pattern is the onion's response to different
environmental and climatic conditions encountered in its life cycle. Successful growers and shippers
take advantage of this fact. To maximize yield and quality, onions should be harvested only when
mature. The bulbing phase is often very rapid and occurs near the end of the onion's active growth
period. During this time, the onion tops will begin to fall over and die. Onions should be ready to
harvest when approximately 10 to 20 percent of the tops have fallen over. Harvesting begins with a
shallow undercutting 1 to 2 inches below the bulbs. Undercutting initiates and hastens the onion's
change from growth to dormancy. Defective onions,i.e. sprouted, insect damaged, sun scalded, green,
bruised) should be discarded.
Drying
For optimum storage quality, onions must be cured soon after harvest by placing them in uncontrolled
sun drying conditions or a drying room at 20-30°C and 70% relative humidity for 12 to 24 h. Curing
decreases the incidence of neck rot, reduces water loss during storage, prevents microbial infection,
and is desirable for development of good scale color. To be transported or stored for any length of
time, onions must be thoroughly dried and in a state of complete dormancy. Onions that are not
completely dormant are subject to infection by decay organisms and are sensitive to bruising and
other mechanical damage. There is no alternative to complete drying and proper postharvest handling.
Several obvious physiological conditions indicate thorough drying. These include the complete drying
of roots, foliage, and several layers of skin on the bulb. The dry skins should have a uniform color and
texture. The best indicator of complete drying is the condition of the neck of the onion. The neck
should be dry nearly to the surface of the onion and should not slide back and forth when squeezed
207
between the thumb and forefinger. Onions that are packed before they are thoroughly dry will quickly
decay. The most common postharvest disease is "neck rot," which results when Botrytis and similar
pathogens enter an incompletely dried neck wound. Once an onion is infected, decay cannot be
stopped.
The optimum temperature for long-term storage of onions is 0°C with 65-70% relative humidity. To
ensure a storage life of up to 8 months, onions must be promptly stored after curing. Exposure to light
after curing will induce greening of the outer scales. Pre-mature sprouting in onions reduces
marketing potential. Preharvest application of a sprout suppressant, such as maleic hydrazide, retards
sprouting and prolongs storage life. In this case, wholesalers, retailers, and exporters of onion may
apply maleic hydrazide to retard sprouting and increase shelf life at commercial level. However,
farmers can simply sundry the bulbs and then reduce losses of the product until sold. Different onion
types have different storage potentials. The storage potential of onions follows the order: yellow red,
white, Spanish and sweet. Within each color group, there are significant differences between cultivars
in their storage potential. This shows that farmers in the region should be properly advised on
selection of the appropriate variety or cultivars, which has proved to have longer storage life.
Onions are susceptible to a number of physiological disorders during storage such as, watery scales,
translucent scales, and freezing injury. Symptoms of watery scales include a thick leathery skin with
watery glassy scales below; freezing injury resembles watery scales is characterized by soft watersoaked scales. Translucent scales are characterized by a water-soaked translucent appearance. These
physiological disorders often become entry points for fungal and bacterial rots. For control of these
problems, effective curing and prompt storage are critical. The relationship between physiological
disorders and microbiological infection because of easy penetration should be made clear to farmers,
wholesalers, retailers, exporters, and development agents dealing with onion production.
Long-term storage
Onions may be stored for several months in a refrigerated storage facility. A temperature of 32 to 36 F
and a relative humidity of 65 to 75 percent is required. Onions will freeze at about 31 F. The effects of
freezing, even for short periods, are cumulative. That is, several short periods below 31 F are just as
damaging as a single longer period. Onions that have frozen become soft and decay quickly. On the
other hand, onions that have been dried and are otherwise in good condition but allowed to remain
above 50 F are subject to sprouting. Sprouting onions cannot be marketed and are very susceptible to
decay and severe weight loss (Table 3.22).
Table 3.22. Percentage of loss at various temperatures
Storage period
Two weeks
One month
Three months
Six months
70F
8.9
10.2
25.2
61.8
40F
5.2
7.0
15.9
32.7
34F
5.3
6.1
10.6
14.0
Storage of dried onion bulbs
Onions are best suited to low humidity in storage. Onions will sprout if stored at intermediate
temperatures. Pungent types of onions have high soluble solids and will store longer than mild or
“sweet” onions, which are rarely stored for more than one month. For long-term storage, onions are
generally sprayed with maleic hydrazide (MH) a few weeks before harvest to inhibit sprouting during
storage. Table 3.23 shows the storage conditions recommended for these crops.
Table 3.23. Storange requirements of onion
Crop
Onions
Temperature
0-5
28-30
RH (%)
65-70
65-70
208
Potential storage duration
6-8 months
1 month
For bulk storage of onions, ventilation systems should be designed to provide air into the store from
the bottom of the room at a rate of 2 cubic feet per minute per cubic feet of produce. This type of
storage structure may be more appropriate for cooperative producers in Oromiya Region or for market
places to be organized at wereda level specific to their onion production potential. If produce is in
cartons or bins, stacks must allow free movement of air. Rows of containers should be stacked parallel
to the direction of the flow of air and be spaced six to seven inches apart. An adequate air supply must
be provided at the bottom of each row and containers must be properly vented.
Bulk storage:
Fig. 4.31. Storage in cartons or bins: Storage Diseases
Onions are susceptible to Botrytis neck rot during storage. The disease is characterized by grey fungal
growth, often watery in nature, at the neck area and on the outer scales. The infection usually spreads
quickly through the whole onion. Bruising of onion bulbs during harvesting,, storing under humid
conditions, and exposing the inner tissues due to breakage of outer scales increase the incidence of
Botrytis neck rot. Curing onions prior to storage will reduce the incidence of this disease.
Black mould, caused by Aspergillus niger, is characterized by black discoloration at the necks of
onions. The black discoloration can sometimes be found on the outer scales. Bruised onions are more
susceptible to this fungus. Black mould causes the tissues to become water soaked which often
induces bacterial soft rot. Although low temperature storage delays growth of the fungus, exposure of
infected onions to temperatures above 15°C, as occurs during marketing, will accelerate its growth.
Stored onions are also susceptible to blue mould, caused by Penicillium. Penicillium moulds induce
watery soft rot of onion tissues and/or blue-green discoloration at the neck or other tissues.
Minimizing mechanical damage and proper curing often reduces the incidence of this fungus.
Bacterial soft rots caused by Erwinia often occur during storage of onions. Onions infected by
bacterial soft rots often appear healthy on the outside but when cut open some of the inner scales are
brown, water-soaked and have a cooked appearance. A characteristic foul smell often occurs and the
centre core of the onion often slips out when pressure is applied at the base of the onion. Bacterial rots
caused by Pseudomonas infect outer scales are characterized by yellow slime, which produces a sour
odor. Control of fungal and bacterial rots of onions can be achieved by:
•
•
•
•
•
•
Pre-harvest application of a registered fungicide
Harvesting at proper maturity
Minimizing bruising of bulbs
Discarding defective onions
Prompt and effective curing
Storing as quickly as possible
209
Potato
Potatoes for processing are best kept at intermediate temperatures to limit the production of sugars,
which darken when heated during processing. Potatoes meant for consumption must also be stored in
the dark, since the tubers will produce chlorophyll (turning green) and develop the toxic alkaloid
solanine if kept in the light. Potatoes stored for use as "seed" are best stored in diffuse light. The
chlorophyll and solanine that accumulate will aid to protect the seed potatoes from insect pests and
decay organisms. Tropical potatoes must be stored at temperatures that will protect the crops from
chilling, since chilling injury can cause internal browning, surface pitting, and increased susceptibility
to decay. Storing potatoes
When storing potatoes, a field storage clamp is a low cost technology that can be designed using
locally available materials for ventilation and insulation. The example illustrated here employs a
wooden ventilator box and straw (cereal crop straw can be used after drying) for insulation. The entire
pile of potatoes and straw is covered with a layer of soil, which should not be highly compacted. To
reduce heat gain, locate the field clamp in the shade (under a tree, on the cool side of a building, or
under a tarp shade.) In very cold regions, a second layer of straw and soil can be added. In hot
regions, less soil is needed, but more ventilation can be added by constructing chimney-type air
outlets at the top of the clamp.
Simple storage houses for potatoes can be constructed for small quantities of produce. The examples
provided here can store 1 to 2 metric tons are used on farms and in mountain villages. The first is
made from unfinished wooden planks painted white to reduce heat accumulation from the sun and
covered with a large thatched roof for protection from sun and rain. It has a large door on one side for
loading and unloading.
The second storage house is constructed from lath and plaster and mud bricks in a cylindrical form. It
has two doors, one on top for loading, and the other at the bottom for easy removal of potatoes for
sale or consumption. Whitewash helps reduce heat accumulation and a thatch roof protects the
potatoes from rain and sun.
For large quantities of potatoes, a self-supporting A-frame storehouse can be constructed. A pit is dug
about 10 feet deep and wooden air ducts are placed along the earthen floor. The roof of the building is
constructed of wood, then covered with straw bales and a thick layer of soil. The capacity of this
structure can be designed based on the expected yield of potato.
Ducts for ventilation of bulk storage rooms can be laid out vertically as well as horizontally. The
storeroom for potatoes shown below provides for plenty of ventilation using simple materials. The
room can be of any size or shape since air ducts can be positioned to extend evenly throughout.
When loading potatoes into bulk storage, even distribution of the produce is important for proper
ventilation. Uneven loads will inhibit air movement and result in storage losses due to inadequate
ventilation.
210
Even distribution of potatoes in the storeroom:
Storage requirements
Temperature and tuber damage are the two most important factors in successful potato storage. Very
careful handling is the key to preventing damage. Harvesting is best done when the soil is slightly
moist to prevent abrasion and the tubers lifted carefully to avoid damage. Ideally, they should be left
to dry for few hours in the field, collected in field containers and placed in a cool, shady place.
Potatoes for food (ware potatoes) must not be exposed to light for more than a few hours otherwise
they turn green, develop an unpleasant taste, and may become toxic. It is important to make the
distinction between ware potato storage and seed potato storage. The objective of ware potato storage
main is to obtain the maximum quantity of tubers, of acceptable quality to the consumers, at a rate to
meet consumer demand. This requires the lowest possible quantitative and qualitative losses, with no
or little sprouting, kept in the dark to prevent greening and firm tubers, all at an economical cost. In
seed potatoes, storage the objective is to have optimum development of sprouts prior to planting. In
both cases, the farmer requires the maximum return from his investment in time, materials,
equipment, and buildings. Temperature influences the rate of respiration of the tubers, sprout growth,
and the development of microorganisms causing rotting. For example, at a storage temperature of
10°C, the rates of sprouting, rotting and respiration are modest, at 20°C these activities are almost at a
maximum. Ware potatoes can be stored up to six months in tropical highlands without significant
losses provided that:
•
•
•
•
•
the variety of potato is one with a long dormancy or the tubers are treated with a sprout inhibitor if storage
duration is required to continue beyond the period of dormancy;
the potatoes are free from diseases, damage or insect infestation;
storage temperatures are kept to levels that do not induce high rates of respiration;
the relative humidity within the store is kept at sufficiently high levels to reduce water loss from the tubers;
and
the potatoes are not wet as a result of rain or condensation.
Preparing ware potatoes for storage
All potatoes showing greening, any decay or damage should be rejected for storage. Immature tubers
and those showing minor damage or wetting by rain may be put aside for immediate consumption. As
with other root crops potatoes to be stored need to be cured to repair any skin injuries and to promote
the formation of a stronger epidermis to reduces water loss. The principle of curing of roots and tubers
was discussed in section the optimum conditions for curing potatoes are:
•
•
•
Temperature: 15 - 20°C
Relative humidity: 85 - 90%
Duration: 5 - 10 days
211
At farmer level, the curing method proposed for yams in section 4.2.1 is quite satisfactory for
potatoes. If a sprout inhibitor is to be used, it should be applied after the curing operation has been
completed otherwise curing will not take place. Sprout inhibitor should neither be applied to, nor
come into contact with, potatoes to be used as seed.
Low-cost ware potato storage
Simple low-cost storage of ware potatoes is possible in a wide range of structures and conditions if the
basic principles of store design, operation, and management are followed. In the highland tropics
ambient temperatures of 10°C to 15°C at night and 15°C to 18°C during the day make it possible to
use very simple methods of potato storage. In the lowlands of Sub-Sahelian Africa where potato
growing has only recently been introduced there has been no general development and significant
adoption of satisfactory storage systems, although work in this field is still on going.
Clamp storage
The clamp is a simple and inexpensive storage method particularly applicable to the more temperate
regions. The details of design vary considerably but all follow similar lines. CIP recommends (Centro
International de Papa 1981) that tubers are heaped on a bed of straw 1m to 1.5m wide with a
ventilating duct on the floor in the centre of the heap and covered with a layer of about 20 cm of
compacted straw or 30 cm if not compacted. The clamp must be in a well-drained location.
Temperatures inside a ventilated clamp will be approximately those of the ambient temperatures.
The clamp system can be modified to meet local requirements provided nothing is done that will lead
to an unwanted increase in temperature. To avoid too high a temperature in warm climates the clamp
should be shallow, but the length can be increased if necessary to maintain capacity. Where rodents or
other mammals are a nuisances a wire net can be dug at least 15 cm deep into the ground and covered
over the clamp.
Naturally ventilated ware potato stores
There must be sufficient movement of cool air through a heap of potatoes to remove respiratory heat
and keep the potatoes as cool as ambient temperatures will allow. The design of any naturally
ventilated store is based on the principle of natural air convection. This type of store has been the
subject of intensive extension programs by FAO for farmers in the highlands areas. The critical factor
in maintaining the store temperature as near ambient as possible is the size of the heap. Generally, the
maximum height of the pile of potatoes should not exceed 1.2m. If, for any reason store temperatures
are expected to be higher than 25°C, it is better to keep the potatoes in small lots, in small crates or in
shallow layers. The Naturally Ventilated Store introduced by the FAO project was a mudblock
structure; 1.2m long, 1.2m wide and 1.0m high to the eaves with a thatched roof and a capacity of
about 700kg The capacity could be increased by making the store longer. The lower part of the store
was a ventilating chamber or plenum made over a pit about 35cm deep into which was built a stone
foundation wall 15 cm deep to support a mud block wall on the periphery of the pit and rising to
ground level. Wooden sticks (saplings or sawn timber) were spaced two or three centimeters apart and
laid over the stall to make a ventilating floor. A mud block wall was continued upwards for a further
one meter to the eaves. On the windward side of the structure, a ventilation opening was fitted with a
shutter to control ventilation. The storage section was from the false floor up to eaves at one meter
high and was provided with closeable openings for loading and emptying. The roof was a structure of
raffia (or equivalent wood material) covered with grass. Store management was simple. After curing
the potatoes are treated with a sprout inhibiter. During the storage period the shutter on the ventilation
opening is left open at night when ambient temperatures are lowest (13°-18°C) and closed during the
day when temperatures are higher and relative humidities lower. A series of trials, carried out both at
research station and farmer level, compared the FAO store with prevailing storage methods. The
results clearly indicated that the cool night air ventilation and reduced daytime ventilation lead to a
significant improvement in the condition of potatoes after storage over the existing traditional
212
methods. Good quality potatoes could be stored for four months with losses of about 10%. The
advantage of the improved store to farmers was that instead of being forced to sell their entire crop
within a maximum period of two months when market prices are at their lowest level, this new store
allowed them to extend or delay the marketing of their potatoes until prices were more favorable. The construction of the store is limited for the most part to locally available materials, mud blocks,
bamboo or wood poles, wooden shutters and few locally available carpentry items. The cost varies
from 5,000 francs CFA, when all materials, excluding carpentry items, were available on the farm, to
18,000 francs CFA when the farmer pays for all the materials and labor. The cost/benefit ratio was
estimated to be 2.5, based on information provided by farmers who had adopted this technology.
Thus, a capital investment of 18,000 CFA could be recovered after two storage periods.
Naturally ventilated store in the Highlands
Table 3.24. Storability (in months) in naturally ventilated stores
Average Ambient
temperature (°C)
5
10
15
25
30
Seed
potatoes
Light Dark
12
8
8-9
4
4
3
3
1-3
2
1
Ware potatoes
Sprout inhibitor
10
8
6-7
4-5
1
No sprout inhibitor
6
3-4
2-3
Ventilated warehouses
The principle of naturally convicted air ventilation was applied to the storage of potatoes in
warehouses of 7-20 ton capacity. The structures were built of mud block walls with a galvanized
corrugated sheet steel roof. Controllable ventilation louvers, each 70cm x 30cm, were built into the
two long walls, those at the windward side were 50 cm above the ground, and those on the opposite
wall were built at about 30 cm below the eaves level. There was at least one pair of louvers (inlet and
outlet) for every three linear meters of wall. A ceiling of bamboo or raffia was built under the roof on
which was placed a 30 cm thick layer of packed straw to insulate the building from the heat radiated
from the metal roof. Mud block were preferred to cement blocks because their insulation was greater.
The ventilation louvers were opened only at night. The average internal store temperature was 14.5ºC
with a mean minimum outside air temperature (at night) of 10ºC and a mean maximum outside air
temperature of 30ºC. Women organized into pre-cooperatives for the marketing of potatoes operated
more than 50 stores of this type. The potatoes were placed inside small crates (50 x 30 x 30 cm) which
were stacked in rows inside the store, leaving inspection alleys of 80 to 100 cm, wide. Each crate was
marked with the name of its owner but marketing was organized as a group.
213
Seed potato storage
The effect of light on reducing sprout elongation and the physiological ageing process has long been
known. CIP and others have demonstrated how a store using natural diffused light can be used for
storing seed potatoes by farmers in tropical countries. Only a simple shed protecting the potatoes
against rain and direct sunlight, and equipped with shelves on which the potatoes are spread in
shallow layers is needed. After few weeks of storage, seed tubers turn greenish and develop short,
sturdy, and green sprouts. Protection against rodent attacks may be necessary.
Fig.4.32. Diffuse light seed potato stores
Diffuse light storage (DLS) is a low cost method of storing seed potatoes, which has been found to
extend their storage life and improve their productivity. DLS uses natural indirect light instead of low
temperature to control excessive sprout growth and associated storage losses. While the principle that
light reduces potato sprout growth has been long established in scientific literature, the International
Potato Center in Peru (CIP) has adapted the technology for use by potato farmers in developing
countries. The results of DLS have had wide reaching effects within developing countries that depend
on potatoes as a primary staple crop. Since its introduction in 1978, DLS has been rapidly adopted.
Local thatch for the roof and a combination of corrugated plastic sheets and fly screen for the walls
can be used to construct. Basic criteria for a DLS structure is that it have an insulated roof translucent
walls, and adequate ventilation. The adoption of the DLS in some other developing countries
including is remarkably similar. Farmers tend not to build new stores or copy demonstration stores
precisely, but rather to modify existing dwellings to meet their needs and budgets. The transfer of
DLS resolved several of farmer’s problems with potato production. DLS cut storage losses and
increased yields, thus reducing the need to import expensive potato seed. Since farmers produced their
own potato seed they were not dependent on shipping dates of imported seed, and could plant during
optimal conditions. Planting at optimal times resulted in more spaced harvests and provided farmers
with extra time to cultivate another crop. As more farmers adopted DLS reduced its dependency on
foreign seed imports, and brought prestige to their agricultural research and extension programs.
Potatoes stored in diffuse light showed a twelve percent increase over the traditionally stored seed. A
survey was conducted to determine the amount of adoption of DLS technology. The farmers stressed
the marked differences of the shorter and sturdier sprouts, and the subsequent vigor of plants whose
seed had been stored in diffuse light. They noted that short sprouted seed from DLS was easier to
handle during transportation and planting. Respondents indicated that the emergence of DLS seeds
was faster and uniform than traditionally stored seeds. Ninety-five percent of farmers interviewed
who used DLS found that the plants produced from these stores were of better quality and gave higher
yields than those from traditional stores. The other five percent indicated no beneficial yield effects of
DLS. While DLS seems to have been adopted by a large number of farmers, thirty-five percent of the
214
farmers interviewed were still not aware of the technology. These potato growers were from remote
areas. DLS may not be an option for farmers who are very isolated or who cannot afford to sell their
seed or to buy translucent siding. Work needs to be done to address the issue of outreach and resource
availability to isolated farmers.
Tomato
Minimum requirements
Tomatoes should be intact, fresh, and sound. They should be clean, free from foreign matter, offsmell, or taste. Tomatoes should be firm, without spots, cracks, bruises, or chilling injury, which
could result in a glassy appearance. They should be regular in shape and color typical of the variety.
The shelf life of tomato at various temperatures is shown in Table 3.25.
Table 3.25. Approximate shelf life
Temperature (°C)
8
10
12
14
18
20
Days
3
8
10
13
10
8
Ideal conditions
•
•
Mature green 12 to 16°C, 90 to 95 per cent relative humidity; and
Firm ripe 6 to 8°C, 90 to 95 per cent relative humidity
Recommended temperature
•
•
Mature green 12 to 18°C, and
Firm ripe 6 to 10°C
Harvesting
A typical mature green tomato will have jelly-like flesh in all locules. Its seeds are sufficiently
developed. External indicators of fruit maturity are position on the plant, size, shape, and surface
(waxy gloss or sheen). Use a combination of these factors to determine when tomatoes are ready to be
harvested. Delaying harvest until a small percentage of fruits start to show color in the field helps to
insure that green fruits are fully mature.
Grading
During grading of fruits, damaged, rotten, and cracked fruits should be removed. Only healthy,
attractive, clean, and bright fruits should be selected. The grades are mostly based on the condition
and the quality of the fruits and not specifically on their size. However, based on the size of the fruits
three grades are formed: small (<100 g), medium (100-255 g) and large (> 255 g). Retailers normally
do size grading for the local market. Internal urban markets have differential prices for size grades as
against ungraded fruit. 215
Packaging
For local markets, the fruits are packed in bamboo baskets or plastic crates. Plastic crates can be
conveniently stacked one on the other and a contoured rim keeps the product safe and natural and
allows sufficient air circulation. The packing should ensure careful handling i.e. rigid enough to
protect the fruits from being crushed. For exports, the fruits are packed in cardboard telescopic boxes
with capacities of not more than 15 kg, should be used. Size graded tomatoes are pattern packed in
layers to make best use of the box. Cooling and storage
Pre-cooling to about 10°C will be necessary for tomatoes of advanced maturity. Tomatoes are
adversely affected by exposure to low temperatures. Unripe tomatoes are susceptible to chilling injury
below 10°C. Low temperature exposure also adversely affects the development of flavor and color.
Cool chain: Cool chain is essential during the transport of export quality commodity all the way
from the farm to the customer. This helps in maintaining the temperature inside the box at the same
low level as in the cold storage. Stages of the cool chain:
•
•
•
•
•
•
•
•
Cold store at the farm;
Refrigerated truck from farm to the airport;
Cold store at the airport;
Building up of the pallet in a cold store at the airport;
Loading the aircrafts directly from the cold store in a short time;
Cargo aircraft maintains cold store temperature in hold;
Off loading direct into a cold store in the receiving country; and
Refrigerated truck to the customers.
Storage
The main objective in storage after harvest is to control the rate of ripening to extend the marketing
period. As the tomatoes are chilling sensitive, the recommended storage temperatures differ
depending on the fruit maturity. A storage temperature of13 C with 90-95% relative humidity is
recommended for slow ripening. At this temperature, most varieties keep in good condition for 2-3
weeks and change color very slowly. In cold storage, unripe tomatoes can be stored for 4 weeks at a
temperature of 8-10 C with 85-90 % relative humidity. Fully ripe fruits are stored at 7 C with 90%
relative humidity for 1 week.
Transport
Tomatoes are highly perishable in nature hence quick means of transportation is necessary. Tomatoes
are transported by road through tractors, trucks and by rail and air to distant markets. Village produce
is transported to the nearby towns and city market only by road.
Tomato post-harvest disorders and diseases
Chilling injury
•
•
•
•
The less ripe a tomato, the more susceptible it is to chilling injury;
Mature green fruit will be injured by temperatures below 12°C;
Ripe fruit will be injured at temperatures below 5°C; and
Chilling injury in tomatoes is characterized by delayed and blotchy coloration and greater susceptibility to
decay
216
Heat injury
Temperatures above 32°C will cause heat injury in tomatoes, which is characterized by a translucent
streaky appearance to the fruit
Bacterial soft rot (Erwinia)
•
•
Rot may occur at injuries anywhere over the surface of the fruit; and
Bacterial soft rot is easily recognized by the soft, mushy consistency of the affected tissues and is generally
associated with a bad color
Rhizopus rot
•
•
This disease is distinguished from bacterial soft rot by the presence of coarse mould that can be seen by
gently pulling apart the diseased tissue; and
Under humid conditions, the mould may grow out over the lesion
Pepper
Maturity
Peppers mature through three distinct stages during development namely, immature green, mature
green and mature red. From immature green to mature green, pepper fruit increase in firmness and
pungency and the cell walls thicken. No change in color occurs. Mature green peppers are
horticultural mature and can be consumed fresh or in processed form (e.g. caned). Harvesting
immature green peppers could result in poor color and flavor, low yields and short lifespan. the
mature red market, peppers that have not fully ripened and have traces of green color are often
unacceptable for marketing. The color change from mature green to mature red is due to the
conversion of chlorophyll (green) to carotenoids (red or orange). This change from green to red color
can be accelerated using foliar applications of ethephon once color development has been initiated on
the plant. Allowing peppers to turn red naturally on plants requires a long growing season and extends
the harvest period. Ethephon has been used to enhance ripening of bell, chili, pimiento, jalapeno, and
paprika peppers. Two applications of 100 ppm ethephon at 1 week intervals beginning once the
peppers are full-sized and about 30% red can significantly improve color. A single application of
ethephon at higher concentrations may induce fruit abscission and defoliation and decreases yields.
Post-harvest methods for ripening peppers involve spraying ethylene over the harvested fruit. This
method is not always successful because peppers vary in their ability to change color from green to
red once detached from the parent plant. Application of 100 ppm ethylene followed by three days
storage at 20-25°C and 85-90% relative humidity can improve color of chili peppers.
Harvesting, handling and storage
Hot peppers are harvested by removing from the branch and ensuring that the stem rem peppers are
harvested by removing from the branch and ensuring that the stem remains intact and attached to the
fruit. Only hot peppers attaining the required color and size should be harvested and over-ripe soft
fruit removed from the tree and out graded. During harvesting, fruit can be placed directly into plastic
field crates or into smaller buckets, which are then transferred to field crates at the side of the field.
Alternatively, cotton waist bags can be used to collect the peppers, which are then transferred to field
crates. All crates and produce should be kept in shaded conditions, protected from sun, wind and rain.
Harvesting is preferred during the early part of the day; harvesting during or Just after rain is not
recommended as wet conditions enhance the breakdown of the pepper fruit. When transporting from
217
the field to the packing facilities, plastic field crates are required. Transport in sacks or mesh bags
result in mechanical damage. Freshly harvested peppers must be stored between 7 to 10°C and 95%
relative humidity. The typical storage life of peppers under these conditions is 3-5 weeks. Storage life
is limited by moisture loss. Peppers are sensitive to chilling injury when exposed to temperatures
below 7°C. Symptoms of chilling injury include pitting and water-soaked tissue. Physiological
disorders in peppers include blossom-end rot and pepper speck. Dark, sunken lesions at the blossom
end of the fruit characterize blossom - end rot. Pepper speck occurs as spot-like lesions that penetrate
the fruit walls. Fruit showing these disorders will not be store and should be discarded.
Storage diseases
The major post-harvest diseases of peppers are Alternaria and Botrytis rots. Phytophthora rots can
also occur if the pepper fruit are exposed to prolonged periods of heavy rainfall. Fruit infected by
Phytophthora have water-soaked lesions. Fungal rots during storage can be controlled by:
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Promptly cooling harvested fruit;
Avoiding bruising and injury;
Post-harvest hot water dips at 52-55°C for 2 minutes; and
Post-harvest application of registered antimicrobials such as. O-phenylphenol at 98 g/l.
Hot peppers may be stored for four to fourteen days depending on the growing conditions and the
utilization of the correct post-harvest handling techniques.
Export Grading and Packing
Hot peppers should not be washed, as water on the surface will accelerate breakdown; debris or soil is
removed by gentle rubbing. No post-harvest treatments are used to prolong the storage life or to
prevent collapse and breakdown. Hot peppers are graded by hand on either a moving conveyor or a
standard grading table. Conveyor operation is more rapid than standard tables; experienced graders
should line the conveyor to remove reject fruits and allow the r to remove reject fruits and allow the
acceptable fruits to continue to fill directly into cartons. All fruits showing signs of mechanical or
insect damage, disease, undersized or softening should be rejected at this point. The fruits are loose
packed with no separate size grading, assuming that all peppers attain the minimum size
specifications. Net weights are dependent on the market and the importer, varying from 3 to 8 kg. Hot
peppers are packed into cartons according to importer requirements. This is based on color as follows:
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•
Only red peppers;
Mixture of red, green and yellow (may be together or separated in the same carton; and
Only green
Where no cool storage facilities are available, peppers should be graded, packed, and exported within
24 hours of harvesting. Even with cool storage facilities at 12ºC, to ensure high quality on arrival,
export is preferred within 48 hours of harvest. This is particularly apparent with peppers from certain
growing areas, which exhibit short storage and shelf lives. Pre-cooling prior to shipment is advisable,
particularly during the summer months where ambient temperature in importing countries are high
and will accelerate fruit softening.
Post-harvest losses
Mechanical damage
Peppers are susceptible to mechanical damage particularly if transported in sacks or bags.
Mechanically damaged peppers, shown by cracks, splits, and punctures will deteriorate by cracks
splits and punctures will deteriorate rapidly
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Physical factors
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Contact with moisture which remains on the pepper when packed will cause rapid breakdown;
Harvesting during rain is to be avoided; and
Storage and quality is also affected by seasonal factors related to the weather conditions; low quality and
poor storage are shown during the periods June to November
Pathological factors
Infection from microorganisms generally occurs as secondary infection after the fruit has commenced
breakdown and collapsed because of over-ripening and softening
Condition
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Free from soil and debris;
No over-ripe or softening fruit;
Free from microbial infection or insect infestation;
No mechanical damage, splitting or cracking; and
Stems intact and green
3.4. Fruit and Vegetables Processing
Peeled tomato
Preferably, choose cylinder-shaped Italian-style tomatoes, although round-shaped varieties may also
be used.
Raw materials needed are fresh tomatoes; lemon juice; and tomato juice. Materials and equipment
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Aluminum pot with lid;
Glass jars with screw-band or twist-off lids;
Kitchen utensils: knives, plastic or metal containers, sieve, clean cloths; and
Source of heat.
Processing
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Select fully ripe tomatoes with a firm pulp, with no superficial blemishes and of a uniform size.
Wash in clean water and drain.
Place 5 1 of water in a pot on the stove.
Place between 1 and 2 kg of tomatoes in the pot when the water begins to boil for 30 to 60 seconds, until
the superficial layer of the skin becomes soft.
Rapidly remove them by means of a sieve.
Place them in a container with cold water so that the skin will peel off.
Finish peeling the tomatoes by hand and with the help of a knife.
Fill the jars.
In order to get more tomatoes into the jar, tap the bottom of the jar with the palm of your hand.
Add one teaspoon (3 ml approximately) of lemon juice for every 500 g jar.
Add the hot tomato juice (as in the recipe to prepare tomato juice) and leaving a space of 2 cm.
If necessary, place the jars with the lids screwed on loosely in a double saucepan, until the temperature
reaches 80-85°C.
Add more hot juice, if necessary.
Seal the jars with the lids.
Clean the outside of the jars and lids.
Proceed as in the recipe for tomato sauce.
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Tomato Paste/Pulp
The pulp-based concentrate product may be classified in puree (10 Brix°), simple (16 Brix°), double
(29 Brix°) and triple (30-32 Brix°) concentrate. The double and triple concentrates are prepared by
means of vacuum evaporators.
Raw materials needed are fresh ripe tomatoes; and salt. Materials and equipment
The same as those used to prepare tomato juice.
Processing
To prepare the puree, proceed as follows:
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Proceed as in the recipe for the preparation of tomato juice (without adding lemon juice) until the juice is
extracted.
Place the pot with the juice back on the fire and let it concentrate until it reaches 10 Brix°, stirring with a
wooden spoon every now and then to prevent the mixture from sticking.
Once 10 Brix° have been reached, add 1% salt, dissolve and remove the pot from the fire.
Fill the bottles to the top with hot puree and cover.
Sterilize the bottles as indicated in the procedure to make tomato sauce.
To prepare the simple concentrate, proceed as follows:
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•
Concentrate the product until 16 Brix° is reached.
Add 2% salt, dissolve and remove from the fire.
Fill the bottles or jars with the hot product and cover them.
This product must be sterilized. Proceed as indicated in the recipe for the preparation of tomato sauce.
•
•
Label the containers and seal the jar lids with adhesive tape.
Once the container is opened, keep in the refrigerator.
Procedures to produce tomato paste:
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The tomatoes previously selected are cut into halves, to facilitate the extraction and to check whether the
tomatoes are sound;
With an extractor, the pulp is separated from the skin and pips;
The pulp is cooked in the pot till a concentration of 7.5% is reached;
The bottles are filled after a spoonful of lemon juice is poured into each bottle;
The bottles are closed with the help of a capper;
And now, they can be sterilized;
The bottles, washed and labelled, are stored; and
Heating and concentrating the ingredients
Tomato juice
The following is a recipe to prepare tomato juice that may be used to make cocktails and cook with
foods when fresh tomatoes are no longer available on the market.
Raw material
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Fresh ripe tomatoes of 4.2 to 4.5 Brix°
Lemon juice
Optional: salt and pepper to taste
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Materials and equipment
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Pot with lid;
Pulper or disc pulp remover;
Jars with screw-band lids (200 ml approximately) or bottles with crown corks (200 ml approximately);
Manual capper;
Crown corks;
Kitchen utensils: wooden spoon, knife, spoons, funnel and wooden board, various plastic containers,
kitchen cloths; and
Heat production system.
Processing
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Store the raw material in a shed until it is used.
Select the tomatoes according to their degree of maturity. Use ripe tomatoes and eliminate those presenting
signs of rot.
Wash in clean water and drain.
Cut the tomatoes in quarters and eliminate those rotting inside.
Wash the bottles or jars separately and drain.
Place the tomatoes in a pot and cook on a medium fire, stirring them with a wooden spoon every now and
then.
Add two tablespoons of lemon juice for every kg of tomatoes.
Optional: add salt and/or pepper to taste.
Remove the pot from the fire when the contents begin to boil and reach 6.5-6.5 Brix°.
Let the product cool partially.
Extract the tomato juice by passing the product through the pulper.
Pass the skin and seeds a second time through the pulper so as to increase the yield of the juice.
Place the pot with the juice back on the fire and cook until it begins to boil.
Fill the bottles to the top with hot juice.
Proceed as in the recipe to make tomato sauce.
Tomato ketchup
Ingriedient needed to prepare tomato ketchup are listed in Table 4. 25.
Table 4.25. Tomato ketchup prepararions
Ingredient
Tomato pulp
Onion
Sugar
Garlic
Cloves
Cardamom
Black pepper
Cumin seeds
Red chillies powder
Salt
Vinegar
Sodium benzoate
Amount
1 kg
20g
100g
2g
1g
1g
1g
1g
5g
20g
50ml
0.75g/kg of finished product
Potato chips
Essentially potato chips are fried potato slices in which the water is driven out during frying
in hot oil. In essence, oil replaces the water. The crispness and color of the potato are
influenced by:
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The specific gravity (moisture content) and sugar content of the cultivar;
The temperature of the oil;
The speed of movement through the frier; and
The thickness of the chip
Process steps
Frying and moulding: The frying time for stackable potato chips - as much other potato based wet
fried products with similar 0.6 – 0.7 mm thickness - is ranging between 15 and 20 seconds with an oil
temperature of 185 °C. The turnover of the oil in the type of fryer used for stackable potato chips is
generally around 8 hours. Being the typical characteristics of this product its long shelf life, the oil
quality and management must be at the highest possible standards. Cottonseed oil is the preferred
choice for many customers but since it is not easy and economically convenient in many Countries,
refined palm oil remains the most popular choice. The exit of the fryer and the matching with the belt
of the seasoning unit is one of the key points to have a good packaging performance. Considering the
importance of the alignment after frying, different systems have been tested to ‘correct’ any
misalignment of the chips out from the fryer: the result is an integrated system of belts and chains that
maintain the chips in position during all the passages between one belt and the following one.
Seasoning device: The variety of seasonings necessary to cover the market request led to the need
of different seasoning units designed around the seasoning characteristics. A particular volumetric
system gives each row the same volume of seasoning. Due to the different characteristics of the
powders, the design of the delivery system must be able to carry different solutions. Generally, it is
necessary to have at least one system for high bulk density and free flowing seasonings and another
one for the ones with more packing tendency. After dosage of the seasoning, the spreading onto the
chips is done with a series of small vibrating sieves.
Portioning and Packaging: The importance of this section is clear when comparing the shelf
attraction of a can or a nice carton box with a tray in it against the common form/seal bags. The first
phase necessary to obtain a good portioning is the flipping upside down of all chips in order to form a
kind of continuous ‘rope’ that can be handled and moved at much lower speed than the single chips.
After testing many mechanical devices to flip the chips that are coming at a rate from 5 chips per
second up, the system based on a compressed air flow remains the most suitable for the purpose. The
transfer of the ‘rope’ of chips from the flipping to the portioning unit can be made efficiently by
means of vibrating channels. Portioning is a volumetric operation that relies on the uniformity of the
weight of the chips between the rows. Typical portioning are 200 grams, 100 grams or 50 grams. In
some cases - typically in the co-packing - there may be the need of different packing types: cans, flow
pack, trays, plus flow pack. In all these situations, the best option is still the semi-automatic set up. If
the packaging is done automatically, each row is directed to a unit that put the portion of the chips in
the can or in the tray. The package is then checked for weight, nitrogen flushed and sealed. As
mentioned before, one critical element for distribution is the shelf life of the stackable potato chips.
Package quality, very low oxygen residual content, oil quality, are the key elements to guarantee the
shelf life. With can packaging and simple nitrogen flushing a 6 months shelf life is normally achieved.
To reach 12 months, nitrogen flushing and can sealing must be able to maintain a residual oxygen
level of less than 4%.
Dehydration of fruits and vegetables
Fruits
Gently wash all fruits in cold water just before drying to remove dirt, bacteria, and insects.
Thoroughly wash fruits that have skins you will not peel off, such as cherries and prunes. Do not soak
fruit because extended soaking can cause nutrient loss and waterlog the fruit, which increases drying
times. Remove fruit stems and peels. Peels may be left on some fruits, such as apples and peaches, but
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they may become bitter or discolor during drying. Core or pit the fruit and cut it into uniform halves,
quarters, or slices.
Vegetables
Wash vegetables in cold water just before drying. If vegetables are covered with soil, wash them
under clean running water to prevent the dirt from resettling on the food. Do not allow vegetables to
soak in water. Most vegetables should be peeled and trimmed then cut, sliced, or shredded into
uniform pieces. Although peeling some vegetables young zucchini and well-washed carrots is
optional, unpeeled vegetables tend be tougher when dried. Remove fibrous or woody portions and
damage areas. You can prepare pieces with a food slicer or food processor.
Pre treating fruits and vegetables
Although you can dry and store many foods without pretreatment, pretreatment generally improves
quality, particularly for vegetables. Five major reasons for treating foods before drying are to
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•
•
•
preserve color and flavor;
minimize nutrient loss;
stop decomposition (enzyme action);
ensure more even drying; and
extend storage life
Pretreatment methods for fruits and vegetables
Fruit Vegetable Ascorbic acid/citric acid dip Steam blanching Salt solution dip Water blanching syrup blanching Honey dip Sulfiting
Pre treating fruits
Decomposition from enzyme action during storage is less a problem with fruits than it is with
vegetables. Fruits have higher levels of sugar and acid, which counteract enzyme action. Although pre
treating fruit is not necessary, you can use an ascorbic acid/citric acid dip, a salt solution dip ,syrup
blanching, a honey dip, or a sulfiting procedure, Certain fruits such as apricots, pears, peaches, and
some varieties of apples, tend to discolor with drying. Pre treating those fruits can decrease browning
during processing and storage and lower losses of flavor and of vitamins A and C.
Ascorbic acid/citric acid dips: Ascorbic acid/citric acid dips are often used as a pretreatment for
fruits. They prevent fruits such as apples, pears, peaches, and apricots from turning brown when cut
and exposed to air. An ascorbic acid dip also increases the vitamin c content of the dried fruit.
(Ascorbic acid is another name for vitamin c.) Use U.S.P. Ascorbic Acid Or Food-grade ascorbic
acid, which are seasonally available among canning supplies in supermarkets. Vitamin C tablets can
also be used. To prepare an ascorbic acid solution, combine 1/2 teaspoon of ascorbic acid crystals, or
three crushed, 500-milligram tablets of vitamin C with 1 quart water. Stir until the ascorbic acid
dissolves. Place the cut fruit in the ascorbic acid solution. Stir the fruit to ensure even coating. Leave
the fruit in the ascorbic acid solution for about 5 minutes. Approximately1 quart of solution will treat
8 cups of fruit. Pineapple juice or juice from citrus fruits such as oranges, lemons, or grapefruit can
also be used as a pretreatment. These juices contain a mixture of citric and ascorbic acids. However,
citric acid is a weaker acid than ascorbic acid and is less effective as a pretreatment. You can also use
a commercial pretreatment such as the anti-darkening powders often sold with food preservation
supplies. Follow the label directions.
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Salt Solution Dip: Prepare a solution of 2 to 4 tablespoons of salt per gallon of water. Soak fruit for
2 to 5 minutes, and then drain it well.
Syrup Blanching: Prepare fruit for drying. Prepare sugar syrup made with 1 part sugar and 2 parts
water. If desired, use less sugar. Bring the syrup solution to a boil. Add the fruit, simmer for 5
minutes, and then drain the fruit. Place the fruit on drying trays and dry. This fruit product is like a
candied fruit. Honey Dip: A honey treatment for fruit can effectively minimize browning and softening in lightcolored fruit. Prepare a honey-water dip using 1 part honey to 4 parts water. Dip the fruit in the honey
solution immediately after slicing, let it soak for about 5 minutes, and drain well. The dried fruit will
have a slight honey taste
Sulfiting: Either sulfur dioxide treatments, sulfiting or sulfuring, are very effective for retarding
oxidation and browning in fruit. Fruit flavor and storage life may also improve. Almost all
commercially produced light-colored fruits, such as dried apples, pears, and apricots, are treated with
sulfur compounds. However, some people have severe allergic responses to sulfur compounds. They
should not eat or work with dried fruit pretreated with sulfur or sulfite compounds. Sulfuring, a
complicated and potentially dangerous procedure, is no longer recommended. Sulfiting involves
preparing a solution of water and a sulfiting agent and then soaking the cut fruit in the solution. In the
United States six sulfur compounds (sulfur dioxide, sodium sulfite, sodium bisulfite, potassium
bisulfite, sodium metabisulfite, and potassium metabisulfite) have been listed by the U.S. Food and
Drug Administration (FDA) as Generally Recognized as Safe” (GRAS). The most popular sulfiting
agents for home drying are sodium bisulfite, sodium sulfite, and sodium metabisulfite. They should be
either U.S.P. (food grade) or reagent grade (pure). They are available at most winemaking supply
centers and some larger supermarkets.
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Amount of sulfur to add per quart of water
Sodium bisulfite
1/2 to 1 teaspoon
Sodium sulfite
1 to 2 teaspoons
Sodium metabisulfite 1 to 3 teaspoons
The sulfiting process has two steps:
• Prepare the sulfiting solution in a large glass container just before use. Place the cut fruit in the solution. Do
not leave the fruit in the sulfiting solution too long or the fruit will be mushy. Use about 10 minutes for
sliced fruit and 30 minutes for halved fruit. Do not exceed the recommended quantities of sulfites or soak
times; and
• After sulfiting, remove the fruit and drain it well. Some people recommend a quick rinse in cold water before
drying. Place sulfited fruit on drying trays and dry. Drying times for sulfited fruits are longer because the
fruit absorbs some water during soaking.
Allergic reactions to sulfites
Some individuals, particularly those with asthmatic conditions, are highly sensitive to sulfites. During
the drying process, most of the sulfites enter the air, leaving only a trace on the fruit. Nevertheless,
this trace may cause severe allergic reactions in sensitive individuals. Sensitive individuals should not
eat food treated with sulfites or prepare soaking solutions with sulfites. If you use a sulfiting
pretreatment when drying foods, be sure to say so on the label.
Pre-treating vegetables
Blanching (heating in boiling water or steam) is the pretreatment method of choice for vegetables.
Almost all vegetables should be blanched before drying to destroy the enzymes that make vegetables
deteriorate. Blanching keeps vegetables from browning, becoming bitter, or developing off flavors.
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Blanching also cleans and softens vegetables and makes them easier to re hydrate later. Although you
can use boiling water or steam for blanching, vegetables lose more nutrients during boiling.
Steam blanching: Use a steamer or make a steamer out of a kettle with a tight-fitting lid. Place a
colander, wire basket, or sieve inside the kettle. Make sure the food will be above the water level. Add
2 inches of water to the kettle and heat it to boiling. . Place the container with the loosely packed food
in the steamer, cover the kettle tightly, and continue boiling.
Water blanching: Fill a kettle with enough water to cover the food. Bring the water to a rolling boil
and gradually stir in the food. Cover the kettle tightly and boil. You can reuse the water when
blanching more of the same food, adding more water as necessary. If the water appears dirty, replace
it with clean water.
Determining blanching times: Blanching times vary with altitude (higher altitudes require longer
blanching times), the type and texture, of the vegetable, the amount of vegetable and the thickness of
the pieces. Generally, vegetables should feel and taste firm yet tender. They should not be cooked, but
they should be heated all the way through. Test the food by cutting through a piece. If sufficiently
blanched, it will be cooked (translucent) at the center. You should test the food frequently to avoid
over- or under blanching. Under blanching may cause deterioration in storage, poor re-hydration, or
bad color. Over blanching makes, vegetables lose color, flavor, and nutrients and give them poor
texture after re-hydration.
After blanching: Drain vegetables by pouring them directly on the drying trays. If you plan to reuse
the water, place a large pan under the trays. Wipe the bottom of the drying tray with a clean towel to
remove excess water. Draining the vegetables on one tray and then transferring them to the drying
tray results in unnecessary handling. Immediately transfer the blanched vegetables into the dehydrator
so drying can begin while the vegetables are still warm.
Sun and solar drying
Field sun drying, used for large tonnage of fruit and vegetables, can be very inexpensive in areas
where climatic conditions are adequate and additionally labor cost is low.
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The radiant energy of the sun provides the heat to evaporate the water while the wind helps to move the
moisture and accelerate the process;
This type of drying performs well in warm and dry condition in fields or other locations (e.g. In shallow for
light sensitive product like herbs and species);
The temperature of the food during sun drying is usually 50c-150c above ambient temperature;
The time of sun drying depends on the product characteristics and drying conditions and typically ranges
from three to 4 days but can be longer for example three to4 weeks for raisins and apricots;
Several practical methods have been developed to reduce the length of drying time, one of the most
important. Especially for larger production scale .is the application of different product pretreatments before
sun drying egg steaming, immersion in boiling water or sugar and/or salt solutions; and
Another way to reduce sun drying time is to use solar energy concentrators with or without natural or forced
airflow inside the dryer. This technique is normally called solar drying.
Dried tomatoes
For preparation of dried tomatoes, all kinds of tomatoes are used but always ripe ones. Procedures to
be followed to produce tomato paste are given as follows:
•
•
After the preliminary operations, the seedless tomato halves are cut in slices about 6 to 8 mm thick, slices of
the same thickness will require the same drying time; and
Tomato needs no blanching or can be blanched. So, the slices are directly arranged in the family sun-drier
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Dried tomato slices
The drier slices are kept in cellophane bags, firmly closed to protect them from humidity. The product
must be kept in a dry and dark place.
Raw material
Unblemished, fully red, ripe and firm tomatoes.
Materials and equipment Sodium metabisulfite powder, knives, trays, scale, plastic buckets, simple solar dryer and
polyethylene or polypropylene/cellophane bags.
Procedure
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Select unblemished tomatoes of a uniform color;
Wash them in drinking water;
Remove the calyx and peduncle;
Cut the tomatoes lengthwise, in quarters or eights;
Remove the seeds and dry separately in the shade;
Blanch the tomato pieces in boiling water for 1-2 minutes;
Cool in drinking water and drain;
Immerse in a sodium metabisulfite solution prepared with 1 g metabisulfite and 1 l of water. Soak for 15-20
minutes; and
Drain and place on the dryer's trays, in a single layer.
Use trays with a plastic rather than a metal mesh.
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Dry until the pieces become brittle;
Cool and package in polyethylene or polypropylene/cellophane bags;
Pack in cardboard boxes to prevent damage caused by light;
Store in a cool and dry place until the product is consumed; and
The product may be preserved for 1 year. Dried papaya
Raw material
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Fully ripe papaya;
Lemon or lime juice or citric acid;
Sodium or potassium metabisulfite; and
Glycerine for foods
The drying procedure is almost similar to drying of mango bar as presented in the following section.
Dried mango bars
Raw material
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Fully ripe mango;
Sugar;
Lemon or lime juice or citric acid;
Sodium or potassium metabisulfite; and
Glycerine for foods
Materials and equipment
•
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•
Aluminum or stainless steel pot with lid; trays;
Pulper;
Solar dryer;
Cellophane to wrap the bars; and
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•
Kitchen utensils: wooden spoon, knives, funnel, wooden chopping blocks, an assortment of plastic
containers and kitchen cloths.
Processing
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Wash the mangoes and cut them in pieces;
Extract the pulp with the pulper;
Add the ingredients as explained below:
Sugar: 10-15% the weight of the pulp, according to the variety used;
Lemon juice: 2 spoonfuls per kilo of pulp;
Sodium or potassium metabisulfite: 2 g per kilo of pulp;
Mix and heat at 70-80°C;
Remove the foam with the skimmer;
Grease the surface of the trays with glycerin to prevent the product from sticking;
Place the mixture on aluminum or steel trays, at a ratio of 15 kilos per square metre of tray area;
Place the trays in a solar dryer. The dehydration is complete when the product acquires a leather-like
consistency (about 15% moisture);
Place three layers of product on top of each other and cut in small 4 x 4 cm squares;
Wrap each square in cellophane; and
Pack in plastic bags, label and store.
Mango slice
The mangoes are washed, peeled, and cut into 6-8 mm thick slices with a stainless steel knife. To
obtain finished products with quality and long storage life, the mango slices are soaked for 18 hours in
a solution containing: 1 liter boiling water, up to 40 brix (7-800 g) sugar, 3 g/ liter of water potassium
metabisulphite, and 2 spoons per liter of water. The slices thus prepared are drained and placed on
glycerin coated aluminum trays, which are placed in a sundrier. The drying is completed when the
product has a moisture content of 15%. The dried slices (150 g~) are packed in cellophane bags,
labeled and stored in a dry place. Storage life is about 12 months.
Mango Jam
Both ripe fruits and under ripe fruits are used. The mangoes are washed peeled and cut in to small
slices with a stainless steel knife. The amount of sugar required represents 60% of the weight of the
mango prepared. The cooking is done in two stages the first stage consists in adding 70 % of the
amount of sugar calculated, plus 2 spoons of lemon juice per Kg of mango. Stir well during the entire
cook until 55 brix of solids by refractometer is reached. Second stage, this stage consists in adding
30% of the sugar, plus 2 spoon of lemon juice per Kg mango. Stir well during the entire cooking unit
67 brix of solids by refractometer is reached. The jars are filled while the mixture is hot during the
operation the jam mast be stirred with the handle of a wooden spoon in order to get rid of air that has
entered the jars are closed with screw-tops.
Vegetable pickles
One type in this category is represented by other vegetables acidified with vinegar separately or in a
mix (red peppers, sweet green pepper, green tomatoes, cauliflower, etc.). The preparation steps are
similar to the ones used for cucumbers in vinegar. Significant quantities of special mixed vegetables
in vinegar are manufactured in many countries, with the international name of "mixed pickles" with
following composition: small cucumbers - maximum 70 mm in length, sliced carrots, cauliflower,
small onions (less than 25 mm diameter), mushrooms etc. and spices. The vegetables are acidified
separately in vinegar and then are put into receptacles (glass jars); flavored vinegar, salted and
sweetened with acetic acid concentration of 3-5% is poured over them. In the case of lower acetic acid
concentrations, pasteurization at 90°C for 10-20 minutes is applied according to the receptacle size. Papaya pickle
Green papaya is required to make pickle. The papaya should be green and very firm and harvested
before the ripening process starts. If the papaya is used too early it will give a pickle with a bitter-
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milky flavor. The final product can he packed in glass jars or polythene bags (at least 100 micron,
preferably a thicker gauge). The polythene bags are a very cheap form of packaging and can be made
into very small packet sizes, which are appropriate for marketing in rural areas. However, polythene is
not a very good barrier for containing aromas, which attract ants, which in turn, will eat through the
polythene very quickly. The yield of usable fruit from whole green papaya is approximately 70%. The
limejuice can he stored in bulk, if limes are not available when the papaya is in season, using
preservative, (Sulphur dioxide, or Benzoic acid at l000-l500ppm). The garlic can he ground in bulk
and kept for long periods, by mixing it with the salt, which is required in the recipe. To make 200 x
1lb jars of papaya pickle requires approximately 13kg of sugar and 27kg of green papaya (Table
3.26).
Table 3.26. Recipe
Item
Prepared papaya
Sugar
Ground garlic
Ground ginger
Ground mustard seed
Ground fennel seed
Ground cumin seed
Chilli powder
Saffron powder or turmeric powder
Salt
Acetic acid (80%)
Lime juice
%
54.0
36.0
3.0
0.5
0.3
0.3
0.4
0.8
0.1
2.0
0.3
2.o
Method
Wash the whole fruits in clean water and discard any, which is bad. Remove the skin with a stainless
steel knife. Cut the fruit into longitudinal segments and remove the seeds, then cut the segments into
very small pieces (5mm cubes). This can be done by hand or much quicker using a Kenwood dicing
machine. Make a number of cuts in the segments with a sharp stainless steel knife, and then push a
segment through the dicer, which will turn it into very small chips of fruit. Mix the papaya pieces with
the sugar in a stainless steel saucepan; leave the mixture for ten minutes so that the sugar draws out
the water from the fruit pieces. Then boil the mixture for ten minutes to evaporate off some of the
water from the papaya, and soften the fruit pieces. Add all the dry spices to the saucepan; this is to
cook the spices into the fruit pieces. The limejuice and acetic acid is added at the end of the cooking
process. This prevents the loss of volatiles, which is very important in the case of the acetic acid.
The whole batch should he boiled down to 90% of the initial total weight of the ingredients in the
saucepan. This will ensure that the pickle will have the correct consistency. Boiling down to the same
finishing weight means that the same number of jars will be filled each time and produce a standard
product. Hot fill the pickle into jars, which have been cleaned and then steamed to sterilize them, and
are still hot so that the jars do not crack. The lip of the jar should he clean and dry (wipe with clean
tissue paper or steam) before placing the lid on it. Polythene bags do not need to be steamed inside, as
they are usually clean by the very nature of their manufacture. The pickle should not he hotter than
90°C as this will soften the polythene. When tilling the bags no pickle must meet the top of the hag
otherwise it will not heat seal. The simplest way to do this is to use a wide neck funnel (which the
pickle can be pushed down through) which slips inside a tube placed in the opening of the bag. The
hot filling of the pickle into hermetically sealed jars will preserve the product until the jar is opened.
The acetic acid (vinegar) stops the pickle deteriorating once the jar has been opened. The amount of
acetic acid required in the recipe can he calculated using an empirical formula. Acetic acid is used
instead of vinegar because it is much cheaper.
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Quality control
Recommended microbial tests
Control tests for microbial invasion in fresh vegetables must be assayed to analyze the growth of
spoilage and pathogenic microorganisms. Total aerobic, psychrophile, and coliform bacteria counts
are performed in standard plate count agar (SPC) and red violet bilis agar (VRBA). A series of
dilutions are made in sterile 0.1 peptone and then pour plated onto SPC and VRB agars; plates for
total aerobic and coliform bacteria are incubated at 35-37°C ± 2°C for 24/48 hours, and psychrophile
bacteria at 7°C ± 2°C for 7 days, respectively. However, major contaminants and spoilage organisms
in fresh vegetables and fruits or by-products, are moulds and yeasts. These organisms are counted by
using potato dextrose agar (PDA) and poured plates, and are incubated at room temperature for 5 to 7
days.
Nutritional changes
Minimally processed vegetables retain nutritional and fresh-like properties because heat is not a major
detrimental factor during processing. When using controlled or modified atmosphere packaging in
combination with refrigerated storage, prolonged shelf life of vegetable products and retention of
vitamins is favored compared to thermally treated vegetables (e.g., canned vegetables), in which high
amounts of nutrients are lost due to severe temperature treatment.
Changes in sensory attributes and acceptability
Since minimally processed vegetables resemble fresh produce, changes in sensory attributes and
acceptability are minimized during processing. Thus, flavor, texture, and appearance are retained.
Traditional food preservation processes involving high temperature treatments, freezing, or
dehydration produce an adverse effect, however, on the texture, flavor and aroma of processed food
products. The following factors are critical in maintaining the quality and shelf life of minimally
processed products:
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using the highest quality raw product;
reducing mechanical damage before processing; reducing piece size by tearing or by slicing with sharp
knives;
rinsing cut surfaces to remove released cellular nutrients and to kill microorganisms;
centrifugation to the point of complete water removal or even slight desiccation;
packaging under a slight vacuum with some addition of CO2 to retard discoloration; and
maintaining product temperature from 1° to 2°C during storage and handling.
Other undesirable sensorial changes are a result of enzymatic activity in raw vegetable products. Two
groups of enzymes are responsible for these changes: Oxidative enzymes such as (Polyphenoloxidase,
PPO, and peroxidase) in unprocessed vegetable and fruit products cause browning or other changes in
color. Changes in taste and flavor are caused by lipid oxidation due to the action of the enzyme
lipoxygenase. Hydrolytic enzymes cause softening of vegetable and fruit products (i.e.,
pectinecterase, and cellulase enzymes); and sweetening of vegetables and fruits by hydrolysis of the
starch (amylases). Activity of such enzymes can be prevented by applying thermal treatment but since
the products are minimally processed, the use of heat is not a true option. One has to use other barriers
to prevent changes in color such as anti-browning agents, i.e., ascorbic acid, and anti-oxidizing agents
as well as calcium salts to enhance texture firmness of vegetable tissues.
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3.5. Milk Processing
What is milk?
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87% water;
13% solids fat and fat-soluble vitamins it contains and the solids not fat include carbohydrates, protein,
water-soluble vitamins and minerals;
Nearly perfect food;
No other single food can substitute for milk in diet and give a person the same nutrients that you get
from a glass of milk;
Adults 2 cups;
Teenagers 4 cups per day; and
Children 3 cups
Nutrients
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Protein - body building and repair;
Carbohydrates - energy and warmth;
Fats - energy and warmth, carries fat-soluble vitamins ADEK;
Vitamins - Growth, prevents diseases; and
Vitamin D - bones and teeth, prevents rickets
Vitamin A - aids growth, prevents night blindness
Riboflavin (Vitamin B2) - regulates production of energy from dietary fat, carbohydrates and protein.
Minerals - strong bones and teeth, body regulation
Calcium - bones and teeth, prevents osteoporosis
Phosphorus - bones and teeth
Shopping pointers
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Product name;
Pasteurized;
Homogenized;
Ingredients, if any are added; and
Pull date - date on container, indicates that the milk should stay fresh 5 - 7 days after the date stamped
on carton
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Storage tips
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Pick up as one of the last items in store;
Refrigerate as soon as possible;
Use milk in order of purchase from individual refrigerators at home(Put freshest milk in the back and
use the oldest first);
Chill UHT milk before serving. Refrigerate after opened;
Dry milk should be refrigerated after reconstituted;
Do not pour unused milk back into original container;
Close container so milk will not absorb flavors;
Canned milk - store in cool, dry place; rotate and turn cans upside down in storage every few months;
Store dry milk in a cool, dry place. Humidity causes milk to lump and may change color and flavor throw out; and
Freezing milk changes consistency and not nutritional value. Refrigerate to thaw.
Processing of milk
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Pasteurization - is the process of heating raw milk to at least 145° and holding continuously for at least
30 minutes or to at least 161° and holding for at least 15 seconds in approved and properly operated
equipment. The milk is then cooled promptly to 45° or lower. Milk’s keeping quality is improved, but
nutrient value is not significantly changed;
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Homogenization - is the process of breaking up milk fat into smaller globules, which disperses them
permanently in a fine emulsion throughout milk. This is done in a homogenizer where milk is forced under
high pressure through very tiny openings. Nothing is added or removed. Homogenization results in the
formation of a softer curd during digestion;
Fortified - is the addition of one or more vitamin, minerals, or proteins not naturally present in a food. The
term, fortified, also applies when added nutrients include one or more naturally present in the food; and
Ultra-pasteurization - is the process of heating raw milk for two to four seconds at 275 to 300°, then
aseptically packaging it to stay fresh from 60 to 90 days. The product should be kept under refrigeration.
After opening, it will hold only as long as any other milk.
Forms of milk
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Raw milk - fresh, unpasteurized milk straight from the cow;
Whole milk - contains not less than 3.25% milk fat. It must contain not less than 8.25% solids-not-fat.
Almost all whole milk marketed is also fortified with vitamin D;
Low fat milk - has had sufficient milk fat removed to bring the levels between 0.5 and 2%. It also contains
at least 8.25% solids-not-fat. It must contain 2000 IU of vitamin A per quart. Vitamin A is added to offset
its loss caused by removal of some o the milk fat. You can find milk in this category labeled as low fat, 2 %
milk, and 1% milk;
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Skim milk - also called nonfat milk, has had sufficient milk fat removed to bring the level to less than
0.5%. It must contain not less than 8.25% solids-not-fat and must be fortified with vitamin A;
Chocolate milk - is made by adding chocolate or cocoa and sweetener to 2% milk. It must be fortified
with Vitamin A and addition of vitamin D is optional;
Eggnog - is a mixture of milk, eggs, sugar, and cream. It may also contain added flavorings such as rum
extract, nutmeg, or vanilla. It’s a seasonal product most readily available during the holidays;
Nonfat dry milk - is the product obtained by removal of water only from pasteurized skim milk;
Buttermilk - is made by adding a special bacterial culture to milk to produce the desirable acidity, body,
flavor and aroma characteristic of this product;
Evaporated milk - is a canned whole milk concentrate, prepared by evaporating enough water, under
vacuum, from fresh whole milk to reduce the volume by half. This concentrate is then homogenized,
fortified with vitamin D, packed in cans, sealed and sterilized by heat;
Sweetened condensed milk - is a canned whole milk concentrate, prepared by evaporating enough
water, under vacuum, from fresh whole milk to reduce the volume by half. It is pasteurized and sugar added
to prevent spoilage;
Whipping cream - is the fat of whole milk. Heavy cream contains a minimum of 36 percent fat, while
light whipping cream contains 30 to 36 percent fat;
Half-and-half - a blend of milk and cream has 10 to 12 percent fat;
Sour cream - with 18 percent fat, is cream that has been soured by lactic-acid bacteria; and
Yogurt - is a milk product with custard like consistency. It is made by fermenting partially skimmed milk
with special acid-forming bacteria.
Grades of milk
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Grade A - has the lowest bacterial count and is the grade sold in retail stores;
Grade B - safe and wholesome; and
Grade C - safe and wholesome. The grade does not indicate its richness, but applies only to its degree of
sanitation.
Uses of milk
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Beverage - it requires no preparation other than chilling. It can be served hot or cold with meals, as
snacks, and as party foods; and
Milk as an ingredient - Milk contributes to the nutritive value, flavor, texture, consistency, and
browning quality of food products. Milk in all forms can be used as an ingredient in a variety of recipes.
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Principles of milk cookery
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Prevent film or scum formation;
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Prevent boiling over;
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Using a covered container
Stirring the milk during heating
Beating the mixture with a rotary beater to form a layer of foam on the surface
The formation of the film on the boiled milk is the principal reason for the boiling over of milk. A pressure
develops under the scum, which forces the milk to break through the film and boil over the sides of the pan.
Prevent scorching of milk;
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When milk is heated, some of its protein tends to settle out (coagulate) on the sides and bottom of the pan and can
scorch easily unless the milk is heated on a very low heat.
Stirring the milk while it heats helps to thin out the film.
Use a double boiler to avoid scorching.
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Prevent curdling of milk;
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When acid is added to milk, the protein settles out in white clumps, or curds, and separates from the whey causing
curdling. For example: acids in tomatoes can cause milk protein to separate as in tomato soup
Thicken with starch either the milk or the food to be added to the milk. (Example: tomato soup - thicken milk with
four and then add the tomato, or thicken the tomato and then add the milk)
Cook at a low temperature
Use very fresh milk (Milk with a high acid content will curdle when heated; acids can develop from improper
storage)
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Milk substitutes
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Cheese, ice cream, can replace part of milk in diet - but at added cost and they have more
calories;
Cheese and cottage cheese - larger containers cost less; and
Yogurt and ice cream - cost as much as three times a glass of milk
Reducing fat content in recipes calling for mil products
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Use skim or 2% milk for whole milk; and
Use yogurt for mayonnaise
Ultra High Temperature (UHT) Processing
Ultra-high temperature processing or (less often) ultra-heat treatment (both abbreviated UHT) is the
partial sterilization of food by heating it for a short time, around 1-2 seconds, at a temperature
exceeding 135°C (275°F), which is the temperature required to kill spores in milk. The high
temperature also reduces the processing time, thereby reducing the spoiling of nutrients. The most
common UHT product is milk, but the process is also used for fruit juices, cream, yogurt, wine, soups,
and stews. UHT milk was invented in the 1960s, and available for consumption in 1970s. High heat
during the UHT process can cause Maillard browning and change the taste and smell of dairy
products. UHT milk has a typical shelf life of six to nine months, until opened. It can be contrasted
with HTST pasteurization (high temperature/short time), in which the milk is heated to 72°C
(161.6°F) for at least 15 seconds. For example, UHT processing centers have been successfully
installed at Pune, Hyderabad, Baramati and some more projects are in the pipeline in countries. The
aseptically packed milk is produced in a plant sponsored by the National Dairy Development Board.
Two kinds of packs are available; one a tetra-pak in the form of tetrahedron which has a shelf life of
three weeks stored under ambient temperature (without refrigeration) and other a tetra Birk, (Birk
shaped) which has a minimum shelf life of three months without refrigeration. A number of flavored
milk drinks formulated by the cooperative dairies and UHT treated as aseptically packed have also
been introduced in Gujarat and Delhi. With this the Indian Dairy Industry now engaged in product
diversification, value addition and export promotion is uniquely placed to exploit these benefits.
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Nutrition: UHT vs pasteurized milk
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Calories: depending on variety of milk, UHT milk contains the same number of calories as pasteurized
milk;
Calcium: UHT and pasteurized milk contain the same amount of calcium.;
Folate: UHT milk contains less folate than pasteurized milk. UHT milk contains 1 mcg of folate per 100g,
while pasteurized contains 9 mcg; and
Vitamin B12, Vitamin C and Thiamin: Some nutritional loss can occur in UHT milk.
Methods for preparation of milk products fruit yoghurt
Yoghurt is a fermented milk product, which gives nutty flavor. Milk is deficient in vitamin C and iron
and so are the products prepared from it. The addition of fruits in the manufacture of fruit yoghurt will
not only improve the taste but also enhance the nutritional quality of the product.
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Milk is standardized to 3.5 - 4.0% fat;
Skim milk powder is added to it at the rate of 2.07 and sugar at 7.0’/;
The mixture is pre-heated to 35-40°C to dissolve the ingredients;
It is then filtered through muslin cloth;
Milk is then heated to 70°C;
It is then two - stage homogenized at 65°C;
The homogenized milk is then pasteurized;
It is cooled to 43°C;
Milk is then inoculated with starter culture of L. bulgciricus and S. therm ophilus in 1:1 ratio at 2.5 %;
Inoculated milk is poured into cups containing already processed fruit pieces at 15-20%;
Incubation is carried for 3 ½ hours at 42°C or till titratable acidity becomes 0.75 %; and
It is immediately transferred to the refrigerator and stored at 5-7°C.
3.6. Meat Processing
Use of heat
Cooking of meats for immediate consumption increases the keeping time of meat. Meat can also be
cooked before it is preserved at low temperature. Meat is canned in different ways. Some chemicals
are also added to meats such as spices, salt or nitrates and nitrites in curing processes, which affect the
heat processing. Meat can be canned in two ways:
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Meats that can be heat processed. Such meats are called as shelf stable and canned processing temperature
is 98°C; and
Meats that are heated enough to kill the microorganisms. Such types of meats are non shelf stable or
refrigerated to prevent spoilage and processing temperature is 65°C,
Heat can be used in meat products in other ways such as:
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Treatment of meat surfaces with hot water to lengthen the keeping time and may lessen nutrients and color;
Cooking at the packing plant by steam or hot water to reduce the number of microorganisms;
Smoking of meats and meat products helps to reduce microbial number;
Precooking or tenderizing of meats to reduce bacteria1 numbers to some extent but not sterilize; and
Cooking of meats for direct consumption to reduce the microbial content and increase the keeping time.
Use of temperature
Meat is presented by use of low temperatures than any other methods. Chilling is more common than
1ezing.
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Chilling
It is slightly above the freezing point. Storage temperature varies from 1.4 to 2.2°C. The time limit for
chilling storage depends upon the, temperature, relative humidity and their microorganisms. Storage
time can be increased by storage of meats in an atmosphere containing CO2 or ozone.
Freezing
Freezing is mostly used to preserve the meats for long distances. The freezing temperature should be
from 12.2°C to 28.9°C: The bacterial numbers decrease slowly during storage due to freezing process.
By drying
The numbers of microorganisms are reduced by the use of smoking and drying process. Meat
products like dry sausages are preserved by its low moisture content. A dry outer surface on the
ceasing of any sausage is protective. Older methods of drying meats are usually combined with salting
and smoking. Another method of drying meat involves a short nitrate—nitrite cure before drying and
addition of lecithin as an antioxidant and stabilizer.
Use of preservatives
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CO2 or ozone;
Use of heavy salt; and
Use of salt combined with curing and smoking in order to be effective.
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The curing of meats by salting was the method of preservation without refrigeration but now some
curing agents are added. The permitted curing agents are sodium chloride, sugars, sodium nitrite, and
sodium nitrate.
3.7. Food Hygiene and Environmental Sanitation
Food Safety
The food industry is made up of businesses that produce, manufacture, transport, and distribute food
for people. Food production involves many activities that occur on farms, on ranches, in orchards, and
in fishing operations. The retail distribution system consists of the many food operations that store,
prepare, package, serve, vend, or otherwise provide food for human consumption. Most of the food is
fixed in processing plants, restaurants, cafeterias, institutions, and other sites outside the home. These
foods are produced using a variety of processing, holding, and serving methods. There are many
opportunities for food to be contaminated between production and consumption. Contamination is the
presence of substances or conditions in the food that can be harmful to humans. Bacteria and viruses
pose the greatest food safety challenges. Food can be contaminated at the farm, ranch, orchard, in the
sea, at food processing plants, during transports, at retail establishments, and by consumers at their
homes. Sources of contamination include air, water, soil, animals and insects, food handlers, food
contact surfaces, ingredients, and packaging materials. It is important to know how to handle
ingredients of food safely and how to prepare food in such a manner that reduces the risk of
contaminated food being served to clients. In many countries, agencies have been established which
are responsible for protecting food supplies at retail outlets, distribution, and storage systems and
processing plants. The agencies prepare and publish food codes and enact rules and regulations to
protect the public from danger associated with food-borne illnesses. Food-borne illness is the sickness
that some people experience when they eat contaminated food. As a means of preventing outbreak of
harmful food-borne diseases, implementation of a food safety assurance in food establishments and
manufacturing plants has become a common practice. This helps ensure that proper safeguards are
used during food production and service.
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Objectives of sanitation for food plants
Sanitation programs are concerned with maintaining all aspects of good sanitation practices in food
process streams. There are various reasons for the establishing a formal sanitation program.
Regulatory actions are usually initiated and conducted by state agencies in order to make sure that
plants maintain their sanitary conditions. However, most regulatory agencies are understaffed, and
many are reluctant to prosecute unless airtight case can be developed. Plants that are filthy and rife
with people, procedures, and conditions capable of creating potentially unwholesome products may
face trouble in form of consumer complaints and eventual loss of business. The ethics of knowingly
processing and selling a food that has been prepared in an unsanitary manner should also be
considered. The food industries largely are morally committed to producing a wholesome product.
Many cases in which a food has been voluntarily recalled because the processor has discovered a
quality defect probably would not influence 99% of the consumers who purchase it. Failure to make
this commitment may result in economic penalties due to lack of consumer confidence and/or legal
action by consumer groups and regulatory agencies. The objectives of many sanitation programs are:
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to provide a clean manufacturing operation capable of producing wholesome and safe products,
to provide guidance and training for employees in good sanitary practices,
to identify process stages that are pivotal in producing acceptable products, and
to keep the management well informed of the sanitary conditions of the plant and its workers.
The Sanitation Manager
Usually a food microbiologist, food scientist, chemical engineer, or food engineer with a degree is
chosen for this position. The duties of the sanitation manager vary with the product type, company,
type of process, a host of other factors. Formal training is not too important if adequate “in-service”
training is available. In addition to the conducting audits, the product protection manager must serve
as a resource person for all questions relating to sanitation. When and how to clean equipment,
approved baits for bait stations, the status of approved lubricants, and many other questions will be
asked during a normal day. He may also be given with the responsibility of managing pest control
program.
Training
A strong sanitation program needs to be sustained by continual and enlightened training of the all
persons working at the establishment. The trainings deal with sanitation of buildings, the control of
foreign materials, personal hygiene, control of microorganisms, insects and rodents, warehouse and
equipment sanitation, etc. Such training could be developed and presented by the sanitation
coordinator. Trainings are also offered by universities, trade associations, and regulatory agencies.
Such trainings can be tailored to specific needs of companies, plants, or processes. Employees of food
establishment must understand that sanitation is everyone’s responsibility and their cooperation in
every phase of the quality assurance program is an integral part of their job. The transmission of foodborne disease organisms and methods of controlling them (destroying and/or preventing their growth
in food) should be stressed. Training food workers is done by on-the-job training and focus on food
handling procedures.
Management
The management should take the lead in showing great concern regarding the sanitary conditions of a
plant. Without the support of the management, the efforts by the sanitation coordinator or supervisor
cannot result in a truly sanitary operation. The plant manager must show interest in the sanitary
operations by personally and regularly touring the plant and encouraging cleanliness and strict
adherence to Good Manufacturing Practices (GMPs). The penalties for management failing to
understand the importance of good sanitation practices can be severe and in the past have led to the
failure of the entire corporations. These include:
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Regulatory actions as a result of unsanitary conditions, which may lead to product recall and even seizure;
Damaging, unfavorable publicity;
Potential product liability and personal injury suits;
Loss of production; and
Loss of sales due to consumer rejection
The plant engineer and maintenance supervisor also play an important role in the success of sanitation
programs. Once observed and reported, sanitary problems must still be corrected or modified so that
any hazard that might exist is corrected. These managers, therefore, must act as a team with the
sanitation coordinator to make corrections effectively and promptly.
The role of government in food safety
The purpose of government regulation in food safety is to oversee the food producing system and
protect food that is intended for human consumption. Governmental agencies enforce laws and rules
to protect food against adulteration and contamination. Regulatory personnel monitor both the process
and the product to ensure the safety of the food we eat. However, there are not enough inspectors and
other resources to administer adequately the program. The enormous size of the food industry makes
it virtually impossible for regulatory inspectors to monitor effectively all aspects of food safety.
Therefore, food safety programs involve governmental agencies and the food industry working
together to ensure the safety of the food supply. Food Service Sanitation Manual, Food and Beverage
Vending Sanitation Manual, Retail Food Sore Sanitation Guide and other similar codes of practice are
prepared and enacted. Such food codes are revised from time to time with the assistance of experts
from state and local government, industry, professional associations, colleges, and universities.
The role of food industry in food safety
The food industry has accepted greater responsibility for overseeing the safety of its own processes
and products. Consumers expect and deserve food that is safe to eat. If a food establishment is
involved in a food-borne disease outbreak, consumers may retaliate by taking their business elsewhere
or by seeking legal action. Financial loss and damaged reputation are some of the outcomes of a food
borne disease outbreak that can cause a serious harm to the food establishment found responsible for
the problem. One means of preventing the harmful effects of a food-borne disease outbreak is to start
a food safety program in the food establishment. This helps ensure that proper safeguards are used
during food production and service. Obviously, the sanitation program in any food plant is an
essential element of the plant’s overall operations. The concept of designing good sanitation into the
process is an important aspect of this. The result has been the recognition of the great value of systems
approaches to these programs. One of the most widely used of these systems-oriented programs is the
so-called Hazard Analysis and Critical Control Point (HACCP) scheme.
Hazards to food safety
A food borne hazard refers to a biological, chemical, or physical hazard that can cause illness or
injury when consumed along with the food. Biological hazards include bacteria, viruses, parasites, and
fungi. Biological hazards are commonly associated with humans and with raw products entering the
food establishment. Bacteria can cause food borne infections, intoxications, and toxin-mediated
infections. Many of these organisms occur naturally in the environment where foods are grown. Most
are destroyed by adequate cooking, and numbers are kept to a minimum by proper cooling during
product distortion and storage. Biological hazards are by far the most important food borne hazard in
any type of food establishment. They cause most food borne illnesses and are the primary target of a
food safety program. Chemical hazards are toxic substances that may occur naturally, or added during
the processing of food. Examples of chemical contaminants include agricultural chemicals (i.e.,
pesticides, fertilizers, antibiotic), cleaning compounds, heavy metals (lead and mercury), food
additives, and food allergens. Harmful chemicals at very high levels have been associated with sever
poisonings and allergic reactions. Chemicals and other non-food items should never be placed near
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food items. Physical hazards are hard or soft foreign objects in food that can cause illness and injury.
They include items such as fragments of glass, metal, toothpicks, jewelry, adhesive bandages, and
human hair. These hazards result from accidental contamination and poor food handling practices that
can occur at many points in the food chain from the source to the consumer.
Bacteria
Bacteria are one of the most important biological food borne hazards in any food establishment. All
bacteria exist in a vegetative state. Vegetative cells grow, reproduce, and produce wastes just like
other living organisms. Some bacteria have the ability to form spores. Spores help bacteria survive
when their environment is too hot, cold, dry, acidic, or when there is not enough food. Spores are not
able to grow or reproduce. However, when conditions become suitable for growth, the spore will
germinate much like a seed. The bacterial spores can then return to the vegetative state and begin to
grow again. Bacteria can survive for many months as spores. In addition, it is much harder to destroy
bacteria when they are in a spore form. Bacteria are classified as either spoilage or pathogenic
microorganisms. Spoilage bacteria degrade (breakdown) foods so that they look, taste, and smell bad.
It reduces the quality of food to unacceptable levels. Pathogenic bacteria are disease-causing
microorganisms that can make people ill if they or their toxins are consumed with food. Both spoilage
and pathogenic bacteria must be controlled in food establishments.
Bacterial growth
Bacteria need six conditions in order to multiply.
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a source of food;
a mildly acid environment (pH of 4.6 -7.0);
a temperature between 50C and 600C;
time;
oxygen; and
enough moisture.
Number of cells Since many foods naturally contain microorganisms, we need to be sure to control these six
conditions as much as possible to prevent bacteria from multiplying. Bacterial growth follows a
regular pattern that consists of four phases (Figure 4.33). The first phase is the lag phase in which the
bacteria exhibit little or no growth. The bacteria adjust to their surroundings during the lag phase. The
lag phase lasts only a few hours at room temperature. However, the duration of this phase can be
increased by keeping foods at 50C or below.
Stationary phase Lag phase Time
Fig.4.33. Bacterial growth curve
The second phase of bacterial growth is the log phase. Bacterial growth is very rapid during the log
phase with bacteria doubling in numbers every few minutes. The third phase of bacterial growth is the
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stationary phase. The number of new bacteria being produced equals the number of organisms that
are dying off during this phase. The bacteria have used up much of the space, nutrients, and moisture
in the food by this phase of the growth curve. The final phase in the growth curve is the decline phase.
Here bacteria die off rapidly because they lack nutrients and are poisoned by their own toxic wastes.
Source of food
A suitable food supply is the most important condition needed for bacterial growth. Most bacteria
prefer foods that are high in protein or carbohydrates like meats, seafood, dairy products, and cooked
rice, beans, and potatoes.
Acidity
Very acid foods (pH below 4.6), like lemons, limes, and tomatoes, will not normally support the
growth of disease-causing bacteria. Pickling fruits and vegetables preserves the food by adding acids
such as vinegar. This lowers the pH of the food in order to slow down the rate of bacterial growth. A
pH above 7.0 indicates the food is “alkaline.” Examples of alkaline foods are olives, egg whites, or
soda crackers. Most bacteria prefer a neutral environment (pH of 7.0) but are capable of growing in
foods that have a pH in the range of 4.6 to 9.0. Most foods have a pH of less than 7.0 and the range
where harmful bacteria grow is from 4.6 to 7.0. Many foods offered for sale in food establishments
have a pH in this range. Disease-causing bacteria grow best when the food it lives on has a pH of 4.6
to 7.0. Milk, meat, and fish are in this range.
Temperature
Not all bacteria have the same temperature requirements for growth. Psychrophilic bacteria grow
within a temperature range of 00C to 210C. These microorganisms are especially troublesome because
they are capable of multiplying at both refrigerated and room temperatures. Most psychrophilic
bacteria are spoilage organisms, but some can cause disease. Mesophilic (middle range) bacteria grow
at temperatures between 210C and 430C, with most rapid growth at 370C. Bacteria that grow best at
temperatures above 430C are called thermophilic organisms. All thermophilic bacteria are spoilage
organisms.
Time and temperature are the most critical factors affecting the growth of bacteria in foods. Most
disease-causing bacteria can grow within a temperature range of 50C to 600C. This is commonly
referred to as the food “Temperature danger Zone”. Some disease-causing bacteria, such as Listeria
monocytogenes, can grow at temperatures below 50C, but the rate of growth is very slow. Careful
monitoring of time and temperature is the most effective way a food establishment manager has to
control the growth of disease causing and spoilage bacteria.
Time
Under ideal conditions, bacterial cells can double in number every 15 to 30 minutes. Clostridium
perfringens bacteria can double every 10 minutes. For most bacteria, a single cell can generate over
one million cells in just five hours. It is very important not to give bacteria an opportunity to multiply.
Proper storage and handling of food helps to prevent bacteria from multiplying. Because bacteria have
the ability to multiply rapidly, it does not take long before many cells are produced. A rule of thumb
in the foodservice industry is that bacteria need about four hours to grow to high enough numbers to
cause illness. This includes the total time that a food is between 50C and 600C.
Oxygen
Bacteria also differ in their requirements for oxygen. Aerobic bacteria must have oxygen in order to
grow. Anaerobic bacteria, however, cannot survive when oxygen is present because it is toxic to them.
Anaerobic bacteria grow well in vacuum packaged foods or canned foods where oxygen is not
available. Anaerobic conditions also exist in the middle of cooked food masses such as in large
stockpots, baked potatoes, or in the middle of a roast or ham. Facultative anaerobic forms of bacteria
can grow with or without free oxygen but have a preference. Most food borne disease-causing
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microorganisms are facultative anaerobes. Microaerophilic organisms have a very specific oxygen
requirement, usually in the range of three to six percent. Controlling oxygen conditions may not be an
effective way to prevent food borne illness. Regardless of available oxygen, some disease-causing
bacteria will find the conditions suitable for growth.
Moisture
Moisture is an important factor in bacterial growth but it is not the percentage of moisture or “water
by volume” in a food that most affects bacterial growth. Rather it is the amount of “available water”
or water available for bacterial activity. This is expressed as water activity and is designated with the
symbol Aw. Water activity is a measure of the amount of water that is not bound to food and is,
therefore, available for bacterial growth. For example, a fresh chicken has 60% water by volume, and
it is Aw is approximately 0.98. The same chicken, when frozen, still has 60% water by volume but its
Aw is now “0.” Water activity is measured on a scale from 0 - 1.0. Disease-causing bacteria can only
grow in foods that have a water activity higher than 0.85. Many foods are preserved by lowering their
water activity to .85 or below. Drying foods or adding salt or sugar reduces the amount of available
water.
Potentially hazardous foods
Some types of foods have the ability to support the rapid and progressive growth of infectious and
toxin-producing microorganisms. These foods are called “potentially hazardous.” Potentially
hazardous foods (PHF) are usually high in protein or carbohydrates and have a pH above 4.6 and a
water activity above 0.85. Common examples of potentially hazardous foods are red meats, poultry
and raw shell eggs, fish and shellfish, and dairy products. Other potentially hazardous foods are
vegetables such as cooked rice or potatoes, refried beans, and fruits such as cut cantaloupe. Potentially
hazardous foods always require special handing. If these foods are held at temperatures between 50C
and 600C for four hours or more, harmful microorganisms can grow to dangerous levels. Potentially
hazardous foods have been associated with most food borne disease outbreaks. It is critical that the
handling and storage of potentially hazardous foods be controlled to prevent bacterial growth.
Food-borne Illness
Many of us might have experienced some degree of nausea, abdominal pain and cramping, diarrhea,
or vomiting though may not have lasted long enough to be diagnosed. Such experience usually is a
food borne illness. The symptoms of food borne illnesses include one or more of the following:
headache, nausea, vomiting, dehydration, abdominal pain, diarrhea, fatigue, and fever. The type of
microorganism, degree of contamination of the food, and the condition of the person affected
determine the severity of the symptoms. When a living, disease-causing microorganism is eaten along
with a food, it can cause a food borne infection. After ingestion, the organism burrows into the lining
of the victim’s digestive tract and begins to grow in number. Sometimes, the organism may spread to
other parts of the body through the blood stream. Bacteria, viruses, and parasites are examples of
microorganisms that can cause infection. A common type of food borne infection is salmonellosis, a
disease is caused by Salmonella bacteria that are frequently found in poultry and eggs. Intoxication is
caused when a living organism multiplies in or on a food and produces a chemical waste or toxin. If
the food containing the toxin is eaten, the toxin causes an illness. It is known by the name food
poisoning. Common examples of this case are Clostridium botulinum and Staphylococcus aureus.
Intoxication may also occur when an individual consumes food that contains synthetic chemicals such
as cleaning agents or pesticides. A toxin-mediated infection is caused when a living organism is
consumed with food. Once the organism is inside the human body, it produces a toxin that causes the
illness. A toxin-mediated infection is a different from intoxication because the toxin is produced
inside the human body. An example of an organism that causes this type of illness is Clostridium
perfringens.
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Food-borne illness caused by bacteria
Bacteria are classified as spore forming and non-spore forming organisms. A spore structure enables a
cell to survive environmental stress such as cooking, freezing, high-salt conditions, drying, and highacid conditions. Spores are not harmful if ingested, except in a baby’s digestive system, where
Clostridium botulinum can cause infant botulism. However, if conditions in the food are suitable for
bacterial growth and the spore turns into a vegetative cell, the vegetative cell can grow in the food and
cause illness if eaten. Spore-forming bacteria are generally found in foods that are grown in soil, like
vegetables and spices. They may also be found in animal products. Spores are most likely to turn
vegetative when:
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Heat shocked (heating causes to change);
Optimum conditions exist for growth (high protein, high moisture);
Temperatures are in the food temperature danger zone or between 5ºC to 60ºC; and
When the amount of time food is in the danger zone is 4 hours or more.
To prevent spore-forming bacteria from turning to dangerous vegetative state, it is critical that hot
food temperatures be maintained at 60ºC or above and cold foods should be held at 5ºC or below.
Always cook and cool foods as rapidly as possible to limit bacterial growth.
Food borne illness caused by viruses
The viruses that cause food borne disease differ from food borne bacteria in several ways. Viruses are
much smaller than bacteria, and they require a living host (human, animal) in which to grow and
reproduce. Viruses do not multiply in foods. However, a susceptible person needs to consume only a
few viral particles in order to experience an infection. Viruses are usually transferred from on food to
another, from a food worker to a food, or from a contaminated water supply to a food. A potentially
hazardous food is not needed to support survival of viruses. There are three viruses that are of primary
importance to food establishments; Hepatitis A, Norwalk, and Rotavirus. Proper hand washing,
especially after using the toilet, is the key to controlling the spread of food borne viruses.
Food borne illness caused by parasites
Food borne parasites are another important food borne biological hazard. Parasites are small or
microscopic creatures that need to live on or inside a living host to survive. Many parasites can enter
the food system and cause food borne illness. Parasitic infection is less common than bacterial or viral
food borne illnesses. Nematodesare associated with food borne infection from fish. Cyclospora
cayetanensis is present water and transferred to foods. Cryptosporidium parvum and Giardia lamblia
are single-cell microorganisms called protozoa. Giardia is found in the feces of wild animals,
domestic pets, and infected persons.
Food borne illness caused by chemicals
Chemicals hazards are usually classified as either naturally occurring or synthetic chemicals.
Naturally, occurring chemicals include toxins that are produced by a biological organism. Synthetic
chemicals include substances that are added, intentionally or accidentally, to a food during processing.
Examples of naturally occurring chemicals are allergens, various toxins from food products and
synthetic chemicals including cleaning solutions, food additives, pesticides, and heavy metals. About
90% of all allergies are caused by eight foods, namely milk, egg, wheat proteins, peanuts, soy, tree
nuts, fish, and shellfish. The only way for a person who is allergic to one of these foods to avoid an
allergic reaction is to avoid the food. In many cases, it does not take much of the food to produce a
severe reaction. As little as half a peanut can cause a severe reaction in a highly sensitive people.
Toxins produced by mycotic organisms such as molds, yeasts, and mushrooms could be capable of
causing food borne illness. Molds and yeasts can withstand more extreme conditions (more acidic
foods, lower Aw foods) than bacteria can. Most molds and yeasts are spoilage organisms that cause
foods to deteriorate. However, some types of fungi produce toxic chemicals called mycotoxins. Many
mycotoxins have been shown to cause cancer. An important food borne mycotoxin, called aflatoxin, is
produced by Aspergillus spp. molds. Many mycotoxins are not destroyed by cooking.
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Added artificial chemicals
Several chemicals added to foods that may pose a potential health risk. Intentionally added chemicals
may include food additives, food preservatives, and pesticides. Pesticides leave residues on fruits and
vegetables, which can usually be removed by vigorous washing procedure. Non-intentionally added
chemicals may include contamination by chemicals such as cleaning and sanitary supplies. In
addition, chemicals from containers or food-contact surfaces of inferior metal that are misused may
lead to heavy metal or inferior-metal poisoning (cadmium, copper, lead, galvanized metals, etc.).
Food borne illness caused by physical hazards
Physical hazards are foreign objects in food that can cause illness and injury. They include items such
as fragments of glass from broken glasses, metal shavings from dull can openers, staples, unfrilled
tooth picks that may contaminate sandwiches, human hair and jewelry, fingernails, or bandages that
may accidentally be lost by a food handler and enter food. Stones, rocks, or wood particles may
contaminate raw fruits and vegetables, rice, beans, and other grain products. Physical hazards
commonly result from accidental contamination and poor food handling practices that can occur at
previous points in the food chain from harvest to consumer. To prevent physical hazards, wash raw
fruits and vegetables thoroughly and visually inspect foods that cannot be washed (such as ground
beef). Food workers must be taught to handle food safely to prevent contamination by unwanted
foreign objects such as glass fragments and metal shavings. Finally, food workers should not wear
jewelry when involved in the production of food, except for a plain wedding band.
Factors that contribute to food-borne illness
Studies show that most outbreaks of food borne diseases occur because food is mishandled. The
leading factors that cause food borne illness include:
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Time and temperature abuse (inadequate cooking and improper holding temperature);
Poor personal hygiene and improper hand washing;
Cross contamination;
Contaminated ready-to-eat foods such as salad items and processed meats; and
Foods from unsafe sources.
Time and temperature abuse
Controlling temperature is perhaps the most critical way to ensure for safety. Most cases of food
borne illness can be linked in some ways to temperature abuse. The term temperature abuse is used to
describe situations when foods are exposed to temperatures in the danger zone for enough time to allow
growth of harmful microorganisms, and not cooked or reheated sufficiently to destroy harmful microorganisms.
Harmful microbe can grow in potentially hazardous foods when temperatures are between 50C and
600C. An important rule to remember for avoiding temperature abuse is “keep hot foods hot, keep
cold foods cold, or do not keep the food at all.” Keep food temperatures, the temperature inside the
core of a food item, above the temperature danger zone 600C to prevent harmful microbes from
growing. Higher temperatures destroy microbes. However, toxins produced by microbes may or may
not be affected by that. Keep food temperatures below the temperature danger zone 50C to prevent
most microbes from growing. Bacteria that can grow in lower temperatures do so very slowly. There
are unavoidable situations during food production when foods must pass through the temperature
danger zone such as cooking, cooling, reheating, and food preparation (slicing, mixing, etc). During these
activities, the amount of time foods are in the temperature danger zone must be minimized to control
microbial growth. When it is necessary for a food to pass through the temperature danger zone, it
should be done as quickly as possible. In addition, foods should pass through the danger zone as few
times as possible.
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How to measure food temperatures
Maintaining safe food temperatures is an essential and effective part of food safety management. One
has to know how to measure food temperatures correctly to prevent temperature abuse.
Thermometers, thermocouples, or other devices are used to measure the temperature of stored,
cooked, hot-held, cold-held, and reheated foods. Food temperature measuring devices typically
measure food temperatures in degrees Fahrenheit (denoted as 0F), degrees Celsius (denoted as 0C), or
both. It is important that one knows which temperature scale a temperature-measuring device is
indicating.
Thermometer guidelines
Food temperature measuring devices scaled only in Celsius or dually scaled in Celsius and Fahrenheit
must be accurate to ±10C (±1.80F). Food temperature measuring devices scaled in Fahrenheit only
must be accurate to ±20F. Mercury filled and glass thermometers should not be used in food
establishments. Clean and sanitize thermometers properly to avoid contaminating food that is being
tested. This is very important when testing raw and then ready-to-eat food thermometer, wipe off any
food particles, place the stem, or probe in sanitizing solution for at least 5 seconds, then air dry. When
monitoring only raw foods, or only cooked foods being held at 600C (1400F), wipe the stem of the
thermometer with an alcohol swab between measurements.
When and how to calibrate thermometers
Most thermometers have provisions to calibrate them and need to be calibrated: before their first use,
at regular intervals, if dropped, if used to measure extreme temperatures and accuracy is in question.
Boiling Point Method: Immerse at least 2 inches of the stem from tip sensing part of the probe into
boiling water, and adjust the needle or pointer to 1000C (2120F). At higher altitudes, the temperature
of the boiling point will vary. Consult a local health department if there is any question. Ice Point
Method: Insert the probe into a cup of crushed ice. Add enough cold water to remove any air pockets
that might remain. Let the probe and ice mixture stabilize and adjust the needle (pointer) to 00C
(320F).
Measuring food temperature
The sensing portion of a food thermometer is at the end of the stem or probe. On the bi-metal
thermometer, the sensing portion extends from the tip up to the “dimple” mark on the stem. The
sensing portion for digital and thermocouple thermometers is closer to the tip. Accurate readings are
possible only when the sensing portion of the temperature-measuring device is inserted deeply into
the food. Always insert the sensing element of the thermometer into the center or thickest part of the
food. When possible, stir the food before measuring the temperature. Always wait for the temperature
reading to stabilize. The approximate temperature of packaged foods can be measured accurately
without opening the package. Place the stem or probe of the thermometer between two packages of
food, fold the package around the stem, or probe to make good contact with the packaging. For some
prepackaged foods, it may be best to open the package or container and measure the temperature of
the food. To measure food temperatures accurately and safely be sure to:
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use an approved temperature measuring device that measures temperature from -180C (00F) to 1040C
(2200F);
locate the sensing portion of the measuring devise;
calibrate the measuring device using the ice or boiling point method;
clean and sanitize the probe of the temperature measuring device according to procedure; and
measure the internal temperature of the food by inserting the probe into the center or thickest part of the
item.
Preventing temperature abuse
Controlling temperatures in potentially hazardous food is important in almost all stages of food
handling. Frozen foods should be kept solidly frozen until they are ready to be used. Freezing helps to
retain product quality. Proper frozen food temperatures do not permit disease causing and spoilage
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microorganisms to grow. Cold temperatures also help to preserve the color and flavor characteristics.
Frozen foods can be stored for long periods without losing their wholesomeness and quality.
Refrigerated foods are held cold, not frozen. Cold foods should be maintained at 50C (410F) or below.
It is wise not to forget that some harmful bacteria and many spoilage bacteria can grow at
temperatures below 50C (410F), although their growth is very slow. By keeping cold foods at 50C
(410F) or below, you can reduce the growth of most harmful microorganisms and extend the shelf life
of the product. For maximum quality and freshness, hold cold foods for the shortest amount of time
possible. Applying heat is another method to preserve food. To destroy harmful bacteria, food is
heated to proper temperatures. Established safe cooking temperatures are based on the type of food
and the method used to heat the product. Cooked foods that have been cooled and then reheated must
be maintained at 600C (1400F) or above until used. You must keep foods hot to stop growth of
harmful bacteria. There are times during food production when foods must be in the temperature
danger zone. It should be recognized that the time spent in the temperature danger zone should be
minimal for potentially hazardous items. Improper holding temperature of foods is the number one
contributing factor that leads to food borne illness. Spores of certain bacteria like Clostridium
botulinum, Clostridium perfringens, and Bacillus cereus can survive cooking temperatures. It is to be
noted that if spores survive when exposed to ideal conditions they can again become vegetative cells.
The industry for cooling requires food temperatures to go from 600C (1400F) to 50C (400F) in 4 hours.
To destroy many of the bacteria that may have grown during the cooling process, reheat foods to 740C
(1650F) within two hours to prevent the number of organisms from reaching levels that can cause food
borne illness. The preferred method for thawing foods is in the refrigerator at 50C (410F) or below.
This prevents the food from entering the food temperature danger zone. Other acceptable methods for
thawing include using a microwave oven, as a part of the cooking process
Importance of hand washing and good personal hygiene
The cleanliness and personal hygiene of food workers are extremely important. If a food worker is not
clean, the food can become contaminated. Even healthy humans can be a source of harmful
microorganisms. Therefore, good personal hygiene is essential for those who handle foods. Desirable
behaviors include:
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knowing when and how to properly wash hands;
wearing clean clothing;
maintaining good personal habits (bathing and restraining hair; keeping fingernails short and clean; washing
hands after using toilet; etc.); and
maintaining good health and reporting when sick to avoid spreading possible infections.
Thinking of all the things hands touch during a typical work day, the list may include taking out the
trash, covering a sneeze, scratching an itch or mopping up a spill etc. When touching once face or
skin, running fingers through hair or a beard, using the toilet, or blowing once nose, potentially
harmful germs will be transferred to the hands. Staphylococcus aurous, Hepatitis A, and Shigella spp.
are examples of pathogens that may be found in and on the human body and can be transferred to
foods by hand contact. Personnel involved in food preparation and service must know how and when
to wash their hands. Using approved cleaning compounds (soap or detergent), vigorously rub surfaces
of fingers and fingertips, front and back of hands, wrists, and forearms (or surrogate prosthetic
devices for hands or arms) for at least 20 seconds. Remember, soap, warm water, and friction are
needed to adequately clean skin. A significant number of germs are removed by friction alone. A
brush can be helpful when cleaning hands. However, the brush must be kept clean and sanitary.
Thorough rinsing under clean warm running water and cleaning under and around fingernails and
between fingers is essential. Drying hands on apron or a dish towel is prohibited. In addition to proper
hand washing, fingernails should be trimmed, filed, and maintained so that hand washing will
effectively remove soil from under and around them. Unless wearing intact gloves in good repair, a
food employee must not wear fingernail polish or artificial fingernails when working with exposed
food. Always wash hands:
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before food preparation;
after touching human body parts;
after using the toilet;
after coughing, sneezing, using a handkerchief or tissue, using tobacco, eating, or drinking;
during food preparation when switching between raw foods and ready-to-eat products;
after engaging in any activities that may contaminate hands (taking out the garbage, wiping counters tables,
handling cleaning chemicals, picking up dropped items, etc.); and
after caring for or touching animals.
Hands shall be washed in a separate sink specified as a hand-washing sink. An automatic hand
washing facility may be used by food workers to clean their hands. However, the system must be
capable of removing the types of soils encountered in the food operation. Food employees may not
clean their hands in a sink used for preparation or ware washing, or in a service sink used for the
disposal of mop water and liquid waste. Each hand-washing sink must be provided with hand cleanser
(soap or detergent) in a dispenser and a suitable hand-drying device. Hand sanitizing lotions and
chemical hand sanitizing solutions may be used by food employees in addition to hand washing. Hand
sanitizing lotions must never be used as a replacement for hand washing. When washing fruits and
vegetables food workers should not contact exposed, ready-to-eat foods with their hands. Instead, they
should use suitable utensils such as deli-tissue spatulas and tongs. In addition, food establishments
sometimes allow their food workers to use disposable gloves to prevent contaminations of foods.
Gloves protect food from direct contact by human hands. Gloves must be impermeable, i.e. not
allowing anything to penetrate the porous texture of the glove. You must treat disposable gloves as
second skin. Whatever can contaminate a human hand can also contaminate a disposable glove.
Therefore, whenever hands should be washed, a new pair of disposable gloves should be worn. For
example, if you are wearing disposable gloves and handling raw food, you must discard those gloves,
wash your hands, and put on a fresh pair of gloves before you handle ready-to-eat foods. Never handle
money with gloved hands unless you immediately remove and discard gloves. Money is highly
contaminated from handling. If you take latex gloves off by rolling them inside out, the inner surface
of the glove is very contaminated from your skin. Again, if you take disposable gloves off throw them
away. Never reuse or wash disposable gloves - always throw them away.
Outer clothing and apparel
Work clothes and other apparel should always be clean. The appearance of a clean uniform is more
appealing to your guests. During food preparation and service, it is easy for a food worker’s clothing
to become contaminated. If you feel that you have contaminated your outer clothing, change into a
new set of work clothes. For example, if you normally wear an apron and work with raw foods, put on
a fresh, clean apron before working with ready-to-eat foods. Also, never dry or wipe your hands on
the apron. As soon as you do that, the apron is contaminated. Aprons help to reduce transfer of
microbes to exposed food. Hats, hair coverings or nets, and beard restraints discourage workers from
touching their hair or beard. These restraints also prevent hair from falling into food or onto foodcontact surfaces.
Personal habits
Personal hygiene means good health habits including bathing, washing hair, wearing clean clothing,
and frequent hand washing. Poor personal habits are serious hazards in food establishments. A food
worker’s fingers may be contaminated with saliva during eating and smoking. Saliva, sweat and other
body fluids can be harmful sources of contamination if they get into food. Supervisors should enforce
rules against eating, chewing gum, and smoking in food preparation, service, and ware washing areas.
However, food workers are permitted to drink beverages to prevent dehydration. The beverage must
be in a covered container. The container must be handled in a way that prevents contamination of the
employee’s hands, the container, exposed food equipment, and single-use articles. Jewelry, including
medical information jewelry on hands and arms, has no place in food production and ware washing
areas. Rings, bracelets, necklaces, earrings, watches, and other body part ornaments can harbor germs
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that can cause food borne illness. Jewelry can also fall into food causing a physical hazard. A plain
wedding band is the only piece of jewelry that may be worn in food production and ware washing
areas.
Personal health
To reduce contamination risk, sick workers must report to the person in=charge. Shiga toxinproducing Escherichia coli, and Hepatitis A. Food employees must also report when they have
symptoms of intestinal illness such as vomiting, diarrhea fever, sore throat, or jaundice, or a lesion
containing pus such as a boil or infected wound that is open or draining. If a food worker is exposed
to Salmonella typhi, Shigella spp., Shiga toxin-producing Escherichia coli, or Hepatitis A, it must be
reported to the supervisor. All of these diseases are easily transferred to foods and are considered
severe health hazards. Food workers who have been exposed to any of these agents must be excluded
from work or be assigned to restricted activities having no food-contact. Workers diagnosed with one
of these diseases must not handle exposed food or have contact with clean equipment utensils, linens
or unwrapped single-service utensils. Infected wounds should be completely covered by a dry, tight
fitting, impermeable bandage. Cuts or burns on a food worker’s hand must be thoroughly bandaged
and covered with a clean disposable glove. To date there has not been a medically documented case of
Acquired Immune Defiance Syndrome (AIDS) transmitted by food. Therefore, AIDS is not
considered a food borne illness. Employers may not fire or transfer individuals who have AIDS or test
positive for the HIV virus away from food handling activities. Employers must also maintain the
confidentiality of employees who have AIDS or any other illness. Physical disabilities are not
considered as threats either.
Cross contamination
The transfer of germs from one food item to another is called cross contamination. This commonly
happens when germs from raw food are transferred to a cooked or ready-to-eat food via contaminated
hands, equipment, or utensils. For example, bacteria from raw chicken can be transferred to a readyto-eat food such as lettuce or tomato when the same cutting board is used without being washed and
sanitized between foods. Cross contamination also happens when raw foods are stored above readyto-eat foods. Juices from the raw product can drip or splash onto a ready-to-eat-food. In food
establishment germs can be transferred by a food worker, equipment and utensils or another food.
Preventive measures eliminate the possibility of cross contamination between products and may
include the following:
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Always store cooked and ready-to-eat foods above raw products;
Keep raw and ready-to-eat foods separate during storage;
Use of separate equipment such as cutting boards, for raw foods and ready-to-eat foods (color coding may
be helpful for this task);
Keep all food-contact surfaces clean and sanitary;
Prepare ready-to-eat foods first-then raw foods;
Prepare raw and ready-to-eat foods in separate areas of the kitchen;
Avoid bare hand contact with ready-to-eat foods; and
Use good personal hygiene and hand washing.
Other sources of contamination
Utensils used to dispense and serve foods can also be a source of food contamination. Utensils should
be properly labeled to identify the type of food they are used to dispense. During hot or cold holding
of foods the utensils should be stored in the food. This helps prevent contamination from workers to
customers. It also keeps the utensil that contains food out of the temperature. The dispensing utensils
(scoops) for ice and dry storage should be clean and kept in an area that is protected from
contamination. Scoops and tongs that are used in customer service areas also need to be labeled and
kept clean. To ensure that dispensing utensils in customer’s self-service areas are used for the
intended foods, many retail food establishments will attach the dispensing utensil with a string or
chain. Animals are not allowed in food establishments unless they are being used for support or
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special service (i.e., guide dogs for the blind). It is very important not to touch animals during food
preparation and service. If an animal is touched for any reason, hands should be washed before
returning to work. Germs from a worker’s mouth can be transferred to food when the employee uses
improper tasting techniques. A food worker may not use a utensil more than once to taste food that is
to be sold or served.
General sanitary standards for fruits and vegetables
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Quality and health standards and regulations must be strictly applied, or the product will be exposed to
contamination by bacteria, mould and yeasts, thus jeopardizing the expected development of an agro
industrial enterprise
Such measures must be adopted as early as in the production phase, and must continue in the post-harvest,
transportation, storage, preparation and processing phases
In line with these principles, the following sanitary standards must be fulfilled and applied by workers on
the production premises:
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o
Workers must wash their hands and clean their nails carefully before engaging in any process
They must keep their nails short, and if possible, use rubber gloves.
To enter the working area, workers must wear a clean smock, a hair net to protect the food from possible
contamination by hair, and a mask to avoid microbial contamination
The working utensils and equipment must be cleaned appropriately to remove any waste or residual organic
material
The containers (glass jars and bottles) must be washed with hot water before being filled with food
The waste generated by the production process must be removed from the production area on a daily basis
Clean and dry the outside of the containers with the product before labeling and storing
The storage site of the finished product must be clean and free from all possible contamination (it must have been
previously fumigated). It must also be cool and dry
Once the working cycle has been completed, the production area must be left perfectly clean
It will therefore have to be pre-rinsed with water at a temperature of 40°C (to remove about 90% of the dirt),
washed with detergent, and finally rinsed with water at a temperature of 38-46°C
Both the premises and the equipment will have to be disinfected on a fortnightly basis
Caustic soda will be applied first (2%), and then nitric acid (1.5%) at a temperature of 75 0 C after which they will
be rinsed with water
Environmental sanitation and maintenance
Exterior conditions
The exterior of a food establishment includes the building structure, parking, landscaping, doors and
windows. The exterior of the facility must be free of litter and debris that could attract pets and detract
from the aesthetics of the facility. Grass and weeds should be regularly mowed and pulled to eliminate
harborage areas for insects, rodents, and other pests. Walking and driving surfaces should be
constructed of concrete, asphalt, gravel, or similar materials to facilitate maintance and control dust.
These surfaces should also be properly graded to prevent rain water from pooling and standing on
parking lots and sidewalks.
Interior conditions
Proper construction, repair, and cleaning of floors, walls, and ceilings are important elements of an
effective sanitation program. Smooth and easy-to-clean surfaces are needed in food preparation areas,
storerooms, including dry storage areas and walk-in refrigerators, and ware washing areas. For floor
coverings, walls, wall coverings, and ceilings, use non-absorbent materials that are free from cracks or
crevices where soil may lodge, and from imperfections that might cause accidents. To keep them in
good condition, choose surfaces that are resistant to damage and deterioration by water, cleaning
agents, and repeated scrubbing.
Floors
The preferred floor materials in food preparation and ware washing areas include terrazzo, quarry tile,
asphalt tile, and ceramic tile. Concrete may also be used if it has been properly sealed with in epoxy
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or similar material to make it durable and non-absorbent. In food, production and ware washing areas
avoid the use of wood, vinyl, and carpeting. These materials are not easy to clean and they tend to
absorb water, soil, and other forms of contamination. Carpeting is not allowed also in food
preparation areas walk-in refrigerators, ware washing areas, toilet room areas where washing
lavatories, toilets, hand, and urinals are located and refuse storage rooms or other areas subject to
moisture. Floors graded to drains are needed in food establishments where water flush methods are
used for cleaning. In addition, the floor and wall must be coved and sealed. Coving is a curved sealed
edge between the floor and wall that eliminates sharp corners or gaps that would make cleaning
difficult and ineffective. Slips and falls are the most common types of accidents in food
establishments. In many instances, slippery floors cause accidents, which result in personal injury and
broken equipment. Use mats and other forms of anti-slip floor coverings where necessary to protect
the safety of workers. These devices should also be impervious, non-absorbent, and easy-to-clean.
Walls and ceilings
Smooth, nonabsorbent, and easy-to-clean walls and ceilings must be provided in food preparation and
ware washing areas, walk-in refrigerators, and toilet facilities. Light colors enhance the artificial
lighting in these areas and make soil easy to see for better cleaning. In areas that are cleaned
frequently, use walls and wall coverings that are constructed of materials such as ceramic tile,
stainless steel, or fiberglass. Concrete, porous blocks, or bricks should only be used in dry storage
areas unless they are finished and scaled to provide a smooth, nonabsorbent, and easily cleanable
surface. Ceilings should be constructed of nonporous, easily cleanable materials. Studs, rafters, joists,
or pipes must not be exposed in walk-in refrigeration units, food preparation, and ware washing areas,
and toilet rooms. Light fixtures, ventilation system components, wall-mounted fans, decorative items,
and other attachments to walls and ceilings must be easy to clean and maintained in good repair.
Restroom sanitation
Toilet facilities are required for all employees. Employee restrooms must be conveniently located and
accessible to employees during all hours of operation. Toilet facilities near work areas promote good
personal hygiene, reduce lost productivity, and permit closer supervision of employees. A toilet room
on the premises must be completely enclosed and provided with a tight-fitting and self-closing door.
Materials used in the construction of toilet rooms and toilet fixtures must be durable and easily
cleanable. The floors, walls, and fixtures in toilet areas must be clean and well maintained. Supply
toilet tissue at each toilet. Provide easy to clean containers for waste material, and have at least one
covered container in toilet rooms used by women. Poor sanitation in toilet areas can spread disease.
Dirty toilet facilities can also have a negative effect on the attitudes and work habits of the
establishment's employees. Include these areas in the routine cleaning program to ensure they are kept
clean and in good repair. Never store food in restroom areas.
Hand washing facilities
Food workers must know when and how to wash their hands in order to do their jobs safely.
Conveniently, located and properly equipped hand washing facilities are key factors in getting
employees to wash their hands. Locate hand-washing stations in food preparation, food dispensing,
and ware washing areas. Hand washing stations must also be located in or adjacent to restrooms. The
number of hand washing stations required and their installation are usually set by local health or
plumbing codes. A hand washing station must be equipped with hot and cold running water under
pressure, a supply of soap and a means to dry hands. A hand-washing lavatory must be equipped to
provide water at a temperature of at least 380C through a mixing valve or combination faucet. If a
self-closing, or metering faucet is used, it must provide a flow of water for at least 15 seconds without
the need to be reactivated. Equip each hand washing station with a dispenser containing liquid or
powdered soap. The use of bar soap is frequently discouraged by regulatory agencies because bar
soap can become contaminated with germs and soil. Individual disposable towels and mechanical hotair dryers are the preferred hand-drying device. Most local health departments do not recommend
retractable towel dispenser systems because there are too many possibilities for contamination.
Common cloth towels, used multiple times by employees to dry their hands, are also prohibited. Keep
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hand-washing stations clean and well maintained and never use them for purposes other than hand
washing. It is equally important to remember that sinks used for preparing produce and water washing
must not be used for hand washing.
Garbage and refuse sanitation
Proper disposal and storage of garbage and refuse protect food and equipment from contamination.
Refuse is solid waste that is not disposed of through the sewage disposal system. Garbage is the term
applied to food waste that cannot be recycled. Good management of these wastes decreases attraction
of insects, rodents, and other pets to the food establishment. Typically, this involves proper handling
and short-term storage of the materials inside buildings. Outdoor storage bins hold refuse and garbage
for slightly longer periods until pickup. An inside storage room and all containers must be large
enough to hold any refuse, recyclables, and returnable that accumulate in the food establishment.
Trash containers must be provided in each area of the food establishment or premises where refuse is
generated or commonly discarded, or where recyclables or returnable are placed. Trash containers are
not placed in locations where they might create public health nuisance or interfere with the cleaning
of nearby areas. Durable, cleanable, insect and rodent-resistant, leak-proof, and non-absorbent
equipment and receptacles are used to store refuse garbage, recyclables, and returnables. Plastic bags
and wet strength paper bags are normally employed to line receptacles for storage inside the food
establishment or within closed outside receptacles. Equipment and containers used for holding refuse,
recyclables, and returnables must be cleaned regularly as dirty equipment and containers attract insect
and rodents. When cleaning this equipment, care must be exercised not to contaminate food,
equipment, utensils, linens, or single-service and single-use articles. Suitable cleaning equipment and
supplies such as high-pressure pumps, hot water, stream, and detergent must be available to
thoroughly clean equipment and receptacles. Wastewater produced while cleaning the equipment and
receptacles must be disposed of through an approved sanitary sewage system or other system that is
constructed, maintained, and operated according to law. Each food establishment should also have an
outside storage area and enclosure to hold refuse, recyclables and returnables that accumulate. An
outdoor storage surface should be durable, cleanable, and maintained in good repair. Equipment and
receptacles shall be covered with tight-fitting lids, doors, or covers to discourage insects and rodents.
Refuse and garbage should be removed from the premises as needed to prevent objectionable odors
and other conditions that attract or harbor insects and rodents. Outdoor storage areas must be kept
clean and free of litter. Suitable cleaning equipment and supplies must be available to clean the
equipment and receptacles. Refuse storage equipment and receptacles must have drains, and drain
plugs must be in place. Cardboard or other packaging material (that does not contain food residues)
may be stored outside for regularly scheduled pickup for recycling or disposal. If materials are stored
so they do not create a rodent-harborage problem, a covered receptacle is not required.
Pest Control
All food establishments must have a pest control program. Insects and rodents, which spread disease
and damage food, are the targets. These include rats, house mice, house flies, cockroach small moths,
and beetles. Insects and rodents carry disease-causing bacteria in and on their bodies. The key element
of a successful pest control program is prevention. However, no single measure will effectively
prevent or control insects and rodents in food establishments. It takes a combination of three separate
activities to keep pests in check. One must:
•
•
•
Prevent entry of insects and rodents into the establishment;
Eliminate food, water, and places where insects and rodents can hide; and
Implement and integrated pest management program to control insect and rodent pests that enter the
establishment.
Insects
What insects lack in size, they more than make up for in number. Insects may spread diseases,
contaminate food, destroy property, or be nuisances in food establishments. Insects need water, food,
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and a breeding place in order to survive. The best method of insect control is keeping them out of the
establishment coupled with good sanitation and integrated pest management when needed.
Flies
House files, below-files, and fruit files are the types of files most commonly found in food
establishments. The housefly is the one most likely to spread disease. Twenty-one species of flies are
categorized as "disease causing flies" because they are proven carriers of various germs that can cause
food borne illness. When a fly walks over filth some of the material, including bacteria, sticks to its
body and leg hairs. When a fly feeds on waste material, it takes some bacteria into its body. When the
fly goes into an area where food is prepared or eaten, it walks on food and food-contact surfaces
hereby contaminating them. The housefly cannot chew solid food. Instead, the fly vomits on solid
food to soften it before eating it. When vomiting, some bacteria may spread on the food and
contaminate it. Blowflies are usually larger than houseflies and are a shiny blue, green, or bronze
color. Blowflies have a keen sense of smell, thus, are attracted by the odors produced by food
establishments and food-processing plants. Fruit flies are the smallest of the three flies and are
attracted by decaying fruit. Fruit flies are known to spread plant diseases. Their role in the spread of
germs that cause infections in humans is currently being investigated.
Fly control
Eliminate the insect's food supply as a first step to fly control. Food should be stored properly to
protect it from flies. In many cases the main source of flies is improperly stored garbage. Cleaning of
kitchen, dining, and toilet facilities should be a routine practice. Equip windows, entrances, and
loading and unloading areas with tight fitting screens or air curtains to prevent the entry of flying
insects. Insect electrocuter traps are devices used to control flying insects such as months and
houseflies. The traps contain a light source that attracts the insects to a high voltage wire grid. Upon
contact with the grids, the high voltage destroys the flies and other insects. Recent evidence suggests
that insect fragments are produced as the insects are destroyed. These fragments can be a source of
contamination for food and food-contact surfaces. Thus, insect electrocuter traps must not be installed
over a food preparation area and/or must be installed so that dead insects and insect fragments will not
be propelled onto or fall on exposed food; clean equipment, utensils, and linens; and unwrapped
single-service. Chemical insecticides should be applied by a professional pest control operator.
Remember insecticides are a supplement to, never a substitute for, a clean food establishment.
Cockroaches
Different types of cockroaches such as the American, Oriental, and German, can be found in food
establishments. Similar to flies, cockroaches are capable of carrying disease organisms on their body.
They crawl from toilets and sewers into kitchens, running over utensils, food preparation areas, and
unprotected food. They carry bacteria on their legs and body as well as in their intestinal tract.
Roaches avoid light and commonly hide in cracks and crevices under and behind equipment and
facilities. It is possible to have a cockroach infestation and not realize it until they are caught by
surprise some night when a light is turned on suddenly in a room.
Cockroach control
Control of cockroaches requires maintaining good housekeeping both indoors and outside. To avoid
hiding places unwanted materials such as boxes and rags must be removed. No cracks and crevices in
floors and walls and around equipment shall exist. Doors and windows should be tight fitting and if
kept open for ventilation or other purpose, must be protected by screening, air curtains, or other
effective means. Incoming food and supplies must be checked for signs of infestation such as egg
cases and live roaches. Foods must be stored in containers that are insect proof and have tight-fitting
lids. Floors, tables, walls, and equipment should be kept clean and free of food wastes. Frequent
cleaning will help remove egg cases and reduce the roach population. Chemical control is only
recommended in combination with the other control procedures and not as the primary method. It is
recommended that insecticides be applied by a reputable, professional pest control operator. These
individuals know how to handle insecticides to avoid contamination of food and food-contact surface.
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Cockroaches are best controlled by insecticides. Make certain the pest control operator remembers to
treat baseboards, windows, door trim, and under and around appliances. Commercially available baits
can be used in "blind" areas, such as false ceilings. Re-treatment in a few days may be necessary to
kill any young roaches that may have recently hatched.
Moths and beetles
Moths and beetles cause concern since they invade certain foods and can do extensive damage. The
grain beetle, flour weevil and rice weevil are examples of stored beetles can be found in food
establishments. These insects feed on a variety of products including corn, rice, wheat, flour, beans,
sugar, meal and cereals. Small moths and beetles create problems of wasted food and nuisance rather
than disease. Control of moths and beetles begins with proper stock rotation. Use the FIFO (First In First Out) system of stock rotation. All opened packages or sacks should be either used immediately
or stored in covered containers. Clean shelves and floors frequently. These pests thrive on flour, meal,
and cereal products that are spilled on the floor or shelving. Examine incoming shipments for signs
infestation, and keep infested products away from other stock until they are ready for disposal. Keep
dry food storage areas cool. Cool temperatures limit growth of these insects and reduce egg lying.
Insecticides may have to be used to prevent re-infestation of stored food. Pest control operators must
treat only along baseboards, cracks, crevices, and under pallets to avoid contaminating food.
Rodents
Rodents adapt easily to human environments and tolerate a wide range of conditions. They may carry
germs that can cause a number of diseases including salmonellosis, plague, and typhus. Rodents also
consume and damage large quantities of foods each year. The term "domestic" rodents includes
different types of rats, including roof rats, and house mice. Some rats hide in burrows in the ground,
around buildings, in sewers, and eat almost any food such as garbage, meat, fish, and cereal. The roof
rat is a very agile climber and it generally harbors in the upper floors of buildings but is sometimes
found in sewers. Roof rats prefer vegetables, fruits, cereal, and grain for food. The house mouse is the
smallest of the domestic rodents. It is found primarily in and around buildings, nesting in walls,
cabinets, and stored goods. The house mouse is a nibbler and it prefers cereal and grain.
Signs of rodent infestation
It is unusual to see rats or mice during the daytime, since they are nocturnal. It is necessary to look for
signs of their activities. From rodent signs you can determine the type of rodent, whether it is a new or
old problem, and whether there is a light or heavy infestation.
Droppings: The presence of rat or mouse feces is one of the best indications of an infestation. Fresh
droppings are usually moist, soft, and shiny, whereas old droppings become dry and hard. Roof rat
droppings are smaller and more regular in form. The house mouse's droppings are very small and
pointed at each end.
Runways and Burrows: Rats stay in a limited area. They are very cautious and repeatedly use the
same paths and trails. Outdoors in grass and weeds, you can see paths worn down that are 2 to 3
inches wide. Some types of rats prefer to burrow for nesting and harborage. Burrows are found in
earth banks, along walls, and under rubbish. Rat holes are about three inches in diameter whereas
mouse holes are only about one inch in diameter. If a burrow is active, it will be free of cobwebs and
dust. The presence of fresh food or freshly dug earth at the entrance of the burrow also indicates an
active burrow.
Rub-marks: Rats prefer to stay close to walls where their highly sensitive whiskers can keep in
contact with the wall. By using the same runs, their bodies rub against the wall or baseboard. The oil
and filth from the rats’ body create a black mark called a rub-mark. Mice do not leave rub-marks that
are detectable except when the infestation is heavy.
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Gnawing: The incisor teeth of rats grow 4 to 6 inches a year. As a result, rats have to do some
gnawing each day to keep their teeth short enough to use. Gnawing in wood are fresh if they are light
colored and show well defined teeth marks.
Rodent control
Effective rodent control begins with a building and grounds that will not provide a source of food,
shelter, and breeding areas. The grounds around the food establishment should be free of litter, waste,
refuse, uncut weeds, and grass. Unused equipment, boxes, crates, pallets, and other materials should
be neatly stored to eliminate places where pests might hide. Get rid of all unwanted materials that may
provide food and shelter for rodents. This means storing trash and garbage in approved type
containers with tight-fitting lids. Plastic liners help to keep cans clean, but they will not exclude rats
and mice. Garbage must be removed frequently from the food establishment to cut off the food
supply. Rats can enter a building through holes as small as 1/2 inch. Mice can enter through even
smaller holes. Buildings and foundations should be constructed to prevent rodent entry, and all
entrances and loading and unloading areas should be equipped with self-closing doors and door
flashings that will serve as suitable rodent barriers. Metal screens with holes no large than 1/4 inch
should be installed over all floor drains. Traps are useful around food establishments where
rodenticides are not permitted or are hazardous. Live traps can be used for collecting live rats. Check
traps at least once every 24 hours. Killer or snap traps can also be used as part of a rodent-control
program. When using these types of traps, place them at right angles to the wall along rodent
runways. Glueboards are shallow trays that have a very sticky surface. They catch mice when the
mouse's feet stick to the board when they walk on it. Rodenticides are dangerous chemicals that can
contaminate food and food-contact surfaces if not handled properly. Baits should be used outdoors to
stop rodents at the outer boundaries of your property. These substances should be applied by a
professional pest control operator. Baits should be placed in a tamper proof, locked bait box that will
prevent children and pets from being exposed to the toxic chemicals inside. Always make certain that
pesticides are stored in properly labeled containers away from food in secure place. Dispose of
containers safely and know emergency measures for treating accidental poisoning.
Integrated pest management
Modern pest control operators use integrated pest management to control pests in food establishments.
Integrated Pest Management (IPM) is a system that uses a combination of sanitation, mechanical, and
chemical procedures to control pests. Chemical pesticides are used only as a last resort and only in the
amount needed to support the control measures in the IPM program. A five-step program for IPM is
recommended. This consists of inspection, identification, sanitation, application of two or more pest
management procedures, and evaluation of effectiveness through follow-up inspections. There are
many benefits of an integrated pest management program. It is cost effective and more efficient than
programs using only chemicals. IPM is also longer lasting and safer to employees, and customers.
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4. Natural Resource Management
4.1. Agro-forestry
I
N ETHIOPIA FARMERS’ managed garden are found in the southern parts of the country namely
in Gedeo, Sidama areas where coffee-enset, trees and fruit trees with other herbs and annual crops
as well as livestock are produced in combination. The current Forestry College was based at place
called Wondo and the name Genet was later annexed, which has eluded from its paradise garden and
tree,f ruit and undergrowth vegetation mix, signifying Heaven by the King Hailesilase I. who
constructed a palace for his daughter in the paradise garden
According to international evaluation, a place that mimics Heaven on Earth was spotted to be Debre
Ziet (Bishoftu) by the BBC question and answer program, which is confirmed by a woman who
heard over a BBC radio. She is born and brought up in same place. Bishoftu in local traditional
meaning is the land that is blessed by surface and underground water. Presence of large body of
water increase night temperature and reduce maximum temperature there by making the site
comfortable compared to same land, which has no water. From scientific perspective, agro-ecological
potential productivity, species diversity, environmental comfort provision, special quality and
quantity in milk and honey produced by the local people confirms as a real land of honey and milk
however evaluated. Thus it is a land of full of paradise even in the face of being a military base which
psychological creates antagonistic feeling, it still give peace and comfort to man and womankind.
The city deserves to be named as a Garden City. Contemporary, the seedlings are distributed from
this very Earthly-Garden of Bishoftu most big cities of wide climatic range in the nation.
The Konso traditional agroforestry as we shall see in this manual in detail is the best exemplary viable
crop, livestock and tree combination through physical and biological conservation practice in the most
marginal and dry land agro-ecology of the nation. In the central to the north where ox culture and
mono-cropping is dominating, tree enter-crop of Acacia albida and Croton macrostachyus practices
reveal better production in increasing crop yield and in addition provide feed and wood without
displacing the main crop. Agroforestry is an old concept and a new land use system or a practice of
producing perennial plants, crops and animal on the same farmland with the intention of optimizing
an overall output from the combination.
Agroforestry as Strategic Intervention
National land use practice and policy allow mono cultivation to up to 60 %. Prior to crop germination
soil erosion is a common practice in ox culture faming. Such practice being erosive had
unquestionably converted and is converting the green roof of African Mountain to the almost rocky
mountain in the north and even in Central highlands. On the contrary in Sidama and Gedeo
(Wango=1250 people/km2) similar degree of slope under enset, coffee, tree and fruit tree based home
garden of hoe culture farming has less to no problem of soil erosion, population increase,
environmental degradation and famine in relative terms. The ox culture is an antagonistic system in
tree production and conservation. In dry farming, system of Konso and the surrounding nearly 500
people/km2 can fulfill their basic Need. a cabbage tree Moringa stenopetala covers 50% of their daily
need Thus agroforestry is an entry that bridges tree development in changing the wrongly conditioned
habit of the ox plow users and mono croppers.
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Role of Agroforestry in Food Security
The gap in the in production system is the quality aspect which is storage in particular. In the
traditional production system this important factor has been taken care off to the level of rejecting
high yielding crop if its storable quality is low.
Benefits of agroforestry
Generally, agro forestry has the potential to solve many land-use problems. Some of the benefits that
the practice of agro forestry offers are:
•
•
•
•
•
•
•
•
•
•
Soil-fertility improvement, for example,. through fixation of nitrogen or build-up of organic matter;
Provision of fuel wood;
Provision of poles, timber, fruits, medicines, etc;
Improved beekeeping;
Control of erosion;
Stabilizing of river and stream banks, i.e. prevention of siltation;
Improvement of water infiltration in to the soil;
Shrubs can act as live fences against livestock and human beings;
Trees and shrubs can contribute to better microclimate; and
Provision of fodder, especially in the dry season.
The traditional slash-and-burn agricultural system qualifies as an agroforestry system but it has been
argued that it is destructive of forests.
Soil fertility
The potential for agroforestry in the region lies in solving problems related to soil fertility, availability
of forest products, fruit production, and amenities such as shade and beauty. Soil fertility can be
improved or sustained by the addition of vegetative organic matter, i.e. decomposition of leafy
biomass and roots. Further, the ability of certain trees to fix atmospheric nitrogen contributes to better
fertility. This would not only be beneficial to the soil, but would also be cheaper for resource-poor
farmers and provide fodder or firewood. Thus, it would be desirable to disseminate effective
agroforestry technologies that could address the issue of acidic and poor soils.
In Vertisols, water logging is a major problem Broad Bed Furrow Maker farm implement developed
by ILCA has been used to drain the soil. Local furrow has also been used. Tree intercrop like Acacia
albida and other perennial hedgerow plants contribute in draining soils, seepage and increase organic
matter that improves drainage. Unfortunately, such technologies have not yet been developed to the
extent that they can be widely extended to farmers. There is, therefore, a need to focus on indigenous
technologies and to find out how, for example, the catchment biological and physical conservation
management system can be developed to make the production of crops and animal less destructive to
the forests.
Energy
The region is mostly rural and over 90% of the people depend on fuel wood for their energy needs.
Increased tree growing and better management of existing resources could provide for products such
as fuel wood, poles, fruits and timber which have not only become scarce but increasingly expensive.
Thus, such commodities could be produced both for subsistence and for cash. Scarcity of fuel wood
may influence both the amount of food cooked and its type. Further, since fuel wood collection is
women’s work the further away the source of fuel wood the greater their workload becomes.
Consequently, they have less and less time and energy to spend on other activities such as caring for
children or engaging in income-generating activities. Thus, the scarcity of fuel wood has a direct
impact on the family’s nutrition.
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Within an ox culture where mono-cropping is predominantly practiced poor farmers use dung and crop
residue. Cow-dung and crop residue use for fuel is the most land degrading practices. The source of fuel
in this regard is grass family crops fine and high-density shallow rooted plant. They are the most
depleting miner plants of the rich upper A horizon soil. Thus God on purpose made them live only for
some few months with the intention of conserving nutrient and moisture to sustain life on Earth. Even
under natural condition, any grass or crop that has been consumed by human or animal has to be recycled
in the form of droppings and urine. Burning crop residue, cow dung and burring human wastes is the
most nutrient depleting tasks of all wrong acts in conventional agriculture in Ethiopia. In Menz, for
example, where there is no tree at all and the entire land is covered with grass. Fuel is cow dung and some
crop residue. Under agro-ecology potential production classification, it is a high potential cereal zone
with a high rainfall area. Despite being classified under high potential production zone, the tragedy is that
it is an area, which is under permanent relief program in the region. Recent attempt of Eucalyptus
planting by World Vision International Ethiopia has improved the situation in food security and
productivity. In monocropping cereals of ox culture, system long-term gestation of perennial tree growth
is the constraint. In the energy preference ladder, the poor are concentrated in the lower steps. But those
who can afford or those who have large holdings has better chance of planting a tree in principle. Such
aggravated scale of poverty can be reversed through conversion of mono-cropping grass forage and grass
crops to multistory home garden and on farm multi-purpose planting practices
The use of improved cooking practices and stoves other than the traditional three- stone type is
important in the conservation of energy. In Northern Province, there have been efforts to construct
fixed stoves, which are an improvement over the traditional ones. However, energy-conservation
practices should also include better cooking practices, for example:
y
y
y
y
y
y
y
Pre-soaking of certain foods before cooking;
Cover with plastic ,immerse and boil;
Cutting the food into small pieces;
Simmering food instead of rapid boiling;
Covering cooking utensils with tight lids;
Use of dry firewood; and
Consuming raw
Soil Fertility
In addition to providing various products, trees have service function. Many species have the ability to
fix nitrogen from the atmosphere and can play an important part in sustaining or improving soil
fertility and increasingly important as fallow period becomes shorter. Researchers have systematically
been working on development of agroforestry technologies for soil fertility improvement such as
improved fallow with Sesbania sesban.
Nutrition
Food from trees makes supplementary, seasonal, and emergency contributions to the household food
supply. Trees and forests can provide crucial emergency food during huger periods and may provide a
buffer during emergencies, e.g. drought. These foods are characteristically energy rich, but may
require complicated processing. Fruits contribute significantly to the nutritional well-being of people,
especially as snacks. They contribute vitamins A, C, D and E to the diet and thus can be an important
factor in children’s health. Extension officers need to consult with the elders in their areas to learn
about the local trees, which can provide food from leaves, nuts, roots, fruits as can boots of cassava,
evidenced from Moringa stenopetala a cabbage tree and fruits of Syzguime guenensii .
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Components of Agroforestry
Searching for better farming method has continued ever since man domesticated plants and animals at the
birth of agricultural revolution. Agroforestry has become an important part of the new thrust to develop
more sustainable land use to replace destructive techniques since the revaluation. Traditionally wide
variety of foods and materials has been produced for their diverse need, with development, they began
specializing in particular crops, especially cash crops, and such cropping led to single farming system. In
addition to complete clearance of forest, the current development is leading farmers to have few crops in
mono-cultural system. On the other hand, forest and agricultural professionals know and develop only a
narrow portion of life sciences. Despite enormous effort made in developing agriculture for many years,
the problem of land degradation, hunger, and malnutrition continues to be a serious threat to the country.
Drawing wealth of knowledge of science of land management and ecology in integrated system for a
sustainable production seems to be a practical option. Such new interdisciplinary approach of optimizing
system in ecological and economic sense, of short and long-term in farming is a sound approach in rural
farming. On the surface of it, agroforestry may seem a simple amalgamation of farming and forestry.
However, it encompasses other components resources and management involved in given time aspect.
The five major components from which agroforestry definition developed are the following.
•
•
•
•
•
Land;
Environment;
Agriculture (livestock + crop) component;
Forestry component; and
Management strategy
The result of the complex interaction between the components of the system defines agroforestry system.
To select the appropriate agroforestry system that suited to farmer’s objectives, a number of the
component may be varied in agroforestry.
Agriculture and forestry sector components
The three major natural resources, i.e. tree, crop and animal are classified and grouped into two major
components as plant and animal component. The plant component is divided as tree/shrub and crops.
These two sub-components can overlap as shown in the following illustration.
Nature component of structural basis
This classification categorizes three basic sets or elements namely tree, animal and crop. Their
combination in agroforestry system can be called sub system or sub component. These are
combination of the above elements known as:
• Agrisilviculture:
• Silvopastoral:
• Agrosilvopastoral:
• Agro-pastoral:
Crop and trees including shrubs/vines and trees
Pasture/animals and trees
Crops, pasture/animals and trees
Crop and forage(animal) combination
There are basic bases in which agroforestry can be classified from structural, functional socio-economic
and ecological role perspectives. They are explained in the following respective category:
Structural basis: refers to the composition of the components, including spatial admixture of the
woody component, vertical stratification of the component mix and temporal arrangement of the different
components;
Functional basis: refers to the major function or role of the system, mainly of the woody components
(these can be productive, e.g. production of food, fodder, fuel-wood, and so on, or protective, e.g.,
windbreak, shelterbelt, and soil conservation).
Social economic basis: refers to the level of the input of management (low input, high input) or
intensity or scale of management and commercial goals (subsistence, commercial, intimidate);
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Ecological basis: refers to the environmental condition and ecological suitability of the systems, on
the assumption that certain types of the systems can be more appropriate for certain ecological conditions
:there can be a set of AF systems for arid and semi-arid lands, tropical highlands ,and lowland humid
tropics. The agroforestry system in Gurage highland predominantly is line planting of Eucalyptus tree for
windbreak in home garden insect is an example of environmental functional base where the trees can
ultimately be used for construction and fuel function. In the Rift Valley on the other hand, intensive
livestock farming combined with deliberate retention Acacia tortolis for livestock shade and ultimately
for charcoal production for cash income. Thus in agroforestry there are always a multiple basis or roles
that a given plant plays. The variation here is dictated by differences in land location. The objective and
goals of agroforestry can be identified as
•
•
•
•
Long-term economic stability;
Complementary production;
Environmental protection and control; and
Better use of marginal (poor) land
These will be further explained below
Economic stability
In agroforestry system, direct production of tree product is possible for various end uses in integration this
can forms basis for the following cottage and other industries. Value of a tree can be affected by the
shape, size, pruning height, cost of failing the tree transportation cost etc. Time- value of money, the real
value of the tree will increase at first up to a maximum value. After this the net value (relative value that
accounts for the interest rates) will began to decline. See the accompanying graph, which explain this.
Types of product are wood products, food and fodder products, pods and leaves as food, and fodder, and
miscellaneous products: Honey, essential oils medicine. These products demand strict conditions to be
economically viable, they are:
•
•
•
•
•
Improved genetic stock for guaranteed yield;
Quality site suited to the tree species;
Well-planned planting design;
Defined management practice for tending and harvesting; and
Transporting facilities with the economic reach.
Complementary production
Agroforestry system is developed with the objective to complement rather than supplement to and or
competes with conventional agricultural enterprises on a farmer's farm. The complementarity’s is
enhanced though efficient use of environmental resource [light, nutrient, water etc.] in improving
production in combination compared to production feed and food in isolation.
Environmental protection
Tree planting or retention protects soil and ameliorates the environment by
•
•
•
•
controlling soil erosion;
minimizing land degradation;
preserving rural wild life; and
stabilizing extreme temperature
Better use of poor land
Planting of appropriate tree species can have positive effect and used to reclaim saline prone land. It also
yields the following effects
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•
•
•
•
improve soil structure drainage;
control weeds;
bring leached nutrient to surface (recycled); and
improve fertility status of the soil through nitrogen fixation
Output and benefits of agroforestry can be summarized as:
• tree planting in a row along contour stabilizing soils on slopes as biological structure;
• agroforestry with a diversity of production has an advantage over other components of agriculture in being
flexible form of land use;
• allow livestock and crops to be grown on same unit without complete displacement;
• improve nutrition status of human and farm animal through inclusion of fruit and vegetable trees and provision of
protein reach green fodder for animal in dry season;
• crop/fodder yield increase by complementary relationship;
• the major livestock production problem is feed shortage and sustainability. Agroforestry supplements an out-ofseason fodder, in form of green feed and protein rich supplement; and
• other indirect uses of Agroforestry
Agroforestry role in landscape
Tree configuration in agroforestry intervention allows a mix of other plants of shallow rooted crops or
pasture to occupy upper space in underground and lower strata in the above ground space. The trees
generally play a deeper biological conservation role in less intense density in tree crop or tree-pasture
mix. In general, tree in the landscape tree perform the following functions:
•
•
•
•
•
•
•
Reduce ground level wind velocity so reducing losses of soil moisture and soil drift when trees on
planted/retained as wind break;
Reduce rain drop intensity, thus reduces primary cause of soil erosion by water;
Increase infiltration, reduce run off and surface erosion and subsequent lake siltation and death;
Provision of high level of fresh organic matter supplied as leaf and bark litter promotes soil aggregation, which
in turn, decreases the susceptibility of the soil erosion;
Tree roots bind the soil together, strengthening and consolidating the immediate area reducing soil movement;
prolong soil moisture in dry season of the remaining rain water even after intercepted reduction (example coffee
shade trees, moisture under Acacia aldida canopy 1.5-2 times compare to open
Trees restore the hydrological balance of the hydrological cycle from environmental conservation viewpoint.
Trees can combat salinity
The presence of deep rooted trees reduce salty matter table down, while the removal of trees and
replacement with Shallow rooted crops of pasture will increase the volume of water recharge to the
ground water. It results in salt-water rise to the surface and causes salinity especially in low land
warmer area.
Mixed planting
Plants are classified in terms of gestation period as annual, biennial, and perennial plants. They can
also be classified as race, variety, genus, family order and so on. One can classify in terms of height,
root spread, and depth. The principal classification of different storey system is primarily important in
terms of optimum above and underground resource trapage that increases complementary production
relation per unit area. Mixing of Rhyzobia bacteria harboring plant like leguminous plant with none
harboring is another important natural mixing that assists complementary production in nature.
Mixing is to avert risk due to diversification, which is intended to withstand different climatic and
edaphic constraints.
MP.1 Mixed cropping
Mixed cropping is growing of different annual crops or even same crops of different ecological
requirement. The following crops being annual have no perennial tree mix in them, thus they system
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is not included in agroforestry delineation. The author believes that it is a transitional both conceptual
and practical example between mono-cropping and mixed tree inter-crop/inter-pasture
MP.1.1 mixing the same crop of different variety
For example in Gojam three finger millet varieties is grown in a mix. Based on farmer’s information,
black variety of finger millet grows in dry ecology, while the white one in wet and higher elevation of
much cooler agro-ecology. The red variety is an intermediate that require an intermediate requirement
in temperature and moisture. The objective of mixing this variety is to diversify and reduce risk. In
dry years, black variety performs better while in rainy year the white variety does well. Under any
environmental condition, a finger millet yield loss is unthinkable unless a drought prolog for more
than 7 years unlike their neighboring regions that are always a victim of drought. This is not authors’
word but that of the farmers themselves. Finger millet can be stored for a period of 30 years under
local storage conditions. The yield is as low as nine quintal/ha, while that of improved maize with
modern input like fertilizer and other chemicals is as much as 40 q/ha. Yet, 40 quintal of maize will
not be compromised by 9 quintals of finger millet. Guaranty in performance sound environmental
impact, storage and food quality are some of the important parameters that the keen farmers are after.
MP.1.2 Mixing related crops of different genus
Barley is mixed with wheat in Tigray for example. The objective is to reduce risk in crop loss. Barley
usually does better in the highlands, collar temperature, and probable moist condition. On the other
hand, wheat can stand adverse condition compared to barley. Even if their above ground and below
ground reach seem having same height and depth respectively, the mix can trap above ground
resource and mine underground nutrient and water compared to mono-cropping. However small there
is a complementary production relation. In Wello, maize and Sorghum are grown in a mix. Similar
principle applies in this regarded as it is explained in barley wheat mix.
MP.1.3 Mixing unrelated crops of different genus
It is a widely adopted practice in most parts of Ethiopia. The most common major crop is tef, it is
usual mixed with safflower, rapeseed, noug, and lupin
MP.2: Tree Crop interaction
A conventional agroforestry tree-crop combination comes across repeatedly. The important details
will be discussed with examples in the sub sections below.
Effect of trees on soil fertility and land degradation
Soil fertility is the capacity of soil to support plant growth, under the given climatic and other
environmental conditions. A narrower view of fertility is sometimes encountered, regarding it as the
content of available plant nutrients. This leads to a restricted view of soil management, to the neglect of
physical and biological properties, and this aspect is better referred to as nutrient content. A wider
concept than sol fertility is that of land productivity, the capacity of land resources as a whole (climate,
water, soil, etc.) to support the growth of required plants, including crops, trees, and pastures, on a
sustained basis. Under natural ecosystems, fertility is maintained by a constant interaction between soils
and plant communities, with a high degree of internal recycling. A natural equilibrium is reached,
changing only slowly with plant succession or, in the longer term, climatic change the use of land for
production, whether as agriculture, agroforestry, or forestry, inevitably disturbs this equilibrium. The
diverse natural vegetation communities are replaced by single crops or a smaller number of plant species,
and carbon and nutrients are necessarily removed from the plant-soil ecosystem as harvest. If production
is to be sustained, ways must be found to maintain or restore fertility. The earliest solution was simply to
clear more land, making use of the fertility built up under the natural ecosystem. This became
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systematized in the practice of shifting cultivation, the earliest form of agroforestry. In modern
agriculture, decline in fertility is checked by a range of practices: return of crop residues, green maturing,
compost, and animal manure to restore organic matter and some nutrients, crop rotation and intercropping
to vary the plant nutrient demands, fertilizer to replace nutrients, and more recently the technique of
minimum tillage. Wetland (paddy) rice cultivation was developed, with its distinctive set of soil processes
for achievement o sustainable production. Plantation forestry also encounters problems of soil fertility,
owing to the large removal of organic matter and nutrients, which takes place during clear felling.
MP.2.4 Cordia /enset inter cropping
Cordia african in the past is a strait tree timber tree. Currently we are unable to produce single stemmed
strait tree. The problem is due to the fact that apical shoot of Cordia african cannot stand direct sun light;
as a result, the shoot is killed. Later on the coppice are initiated forming forked multiple stem. Those
secondary branches in the next dry season experience the same rhythm and again re-branched9secondary
branches). To solve this problem different nurse tree trial has been carried out yet the result was not
promising. Under traditional management in the southern Ethiopia, the farmers developed a technology in
which they plant the tree in inset plantation. Inset is a crop with wide leaves that provides sufficient and
uniform shade and grows as high as 6 or more meters. Cordia africana is planted as tree intercrop at later
stage. Thus, the tree can grow up to 6meters without losing its apical shoot or without branching below
the stated height. Thus using this technique one can grow a strait ball for timber (Cordia is a best quality
timber). Still some experiment has to be carried out to optimize the required quality output.
MP.2.5 Coffee shade tree intercrop
It is a combination where umbrella shaped shade trees are tree intercrop in organic farmers coffee
production is practiced. It is market oriented high vale crop production in a traditional complementary
production relation. Information generated from participatory farmers’ interview has been
summarized in the table. Rainfall is intercepted that mount that reaches the under storey coffee is
much lower and the sizes are much smaller which enables the drops to increase infiltration and
reduces the potential mechanical damage. The farmers’ indigenous knowledge has been illustrated by
the author as follows (Table 4.1)
Table 4.1. Relative appropriateness as a function quality and quantity of coffee product
Function
Shade
Nutrient input
Soil conservation
Impact on test (quality)
Impact on Sustainability and
environmental impact
Grand Total
Grand Mean
Acacia
species
5
4
4.8
5
4.8
Albezia
gummiferra
5
5
5
4.6
4.6
Shade trees
Croton
macrostachyus
3.8
3.8
4
0
3.2
Cordia
africana
3.8
3.4
2.8
1.6
3.2
Meltia
ferruginea
3.8
3.6
3.8
3.6
3.8
93
3.72
121
4.84
74
2.96
74
2.96
92
3.68
Note: - 5=Excellent,4=Very Good 3=Good, 2=Satisfactory 1=no effect, 0= Bad
This is a mix in which perennial plant (tree) exists in the admixture. It thus qualifies the definition of
agroforestry. The other crops in a mix are both annual and biennial. The above combination presented
to show how the mixing system is evolved to illustrate the conceptual and traditional practice under
Ethiopian farmers’ condition. On the other hand, the root depths will not general fit to the
aboveground proportional length trend. For example Acacia albid which is about 10 meters high is
definitely found accessing 3o meters deep in near Mojo at Udie Peasant Association.( information
from water development at Wolinchite and preliminary observation showed a tap root depth of more
than 100 meters. On the contrary, Eucalyptus the tallest broad leaved tree in the world will not have
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the deepest root. Alfalfa with a height of about two meter has a root depth of at least 5 times longer.
Thus root shot ratio of a plant will not keep proportionality. It is clearly illustrated in multi-storey
formation of different crops both above and below ground in traditional mixed tree intercrop in Konso
farming system. The tree crop interaction can be horizontal or vertical inter action. Optimization of
resource utilization in a complementary interaction relationship can be optimized, by selection of the
appropriate species to be combined or management practices that boosts the production of these
components. Such synergy will enable the output of each component to increase holistically compared to
the sum of the components produced individually. The Konso people practice an integrated agroforestry
and soil conservation on terraced land in multi-storey system. This is a practice of long history and one of
the advanced technologies in Ethiopia. They use the limited environmental resources both above and
belowground in an optional way. As they are mixing several crops of different canopy and root reach
level, farmers produce better yield by mixing than planting each crop in mono-cropping practices.
Types of interaction
The production relations of any two components can be competitive directly or indirectly. For example,
trees might have a detrimental effect by shading or harboring wild animals. As a result, the tree can be
subjected to complete clearance in the process of arable or pasture land expansion. On the other hand, it
can have a supplementary production relation; in this case, there will not be any detrimental or beneficial
effect. The complementary relationship in production is a combination of two components where
production can be increased because of combination compared to the sum of each production in isolation
on similar area under the same management and other production factors. It is also a subject to variation
under management or at different time. For example, Faidherbia albida tree inter-crop has a
complimentary relation, the complementarity production relation increases if it is coupled with
management such as pruning of branches. The relative yield increase is high for cereal crops like maize
or millet but decreases for small cereals like wheat and tef.
Agroforestry for livestock production
In agroforestry combination of perennial trees have an important role as feed directly and contribution in
sustainable livestock production in agroforestry system through its service role indirectly.
Shade and shelter
Under extreme cold and high temperature animals of almost all classes need to be sheltered to keep them
in their optimum comfort temperature range for optimum production so do need plants. High temperature
reduces birth rate, production of milk and meat on the other hand cold temperature resulted in loss of
newborn animals. In all cases, the temperature requirement by newly born animals is elevated with a very
narrow range. As a result, their housing or shelter requirement needs to be designed in such a way that it
can keep them in the required temperature ranges. Thus ,a right species selection for shade or
manipulation of a canopy to obtain the right density of porosity level to control both direct sun light and
controlling wind speed to avoid chilling are the most important pieces of information which the research
has to be after.
Table 5.2. Absolute monthly average temperature in drier parts of
Location
Yabelo
Arbaminch
Gidole
Koka
Duration
(year)
1963-70
1960-66
1957-70
1951-57
Mean absolute max.
30.7 (Feb.)
34.3 (Feb.)
29.5 (Feb.)
32.2 (Jun.)
Mean absolute min
(0c)
7.6 (Dec.)
10.5 (Dec.)
6.7 (Jan.)
7.0 (Dec.)
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Wind break
Currently the temperature is increasing during the day and decreasing during the night. In the
highlands, low temperature is the major causes that affect crop or livestock production. Wind on the
other hand aggravates the injury level. In the lowlands high temperature is the major problem, wind
plays a part in the solution. In agroforestry windbreak is one of the technologies that should be
developed for its optimum benefit in a farmland a mixed farming scattered trees have multiple uses
both in pasture and arable land. Acacia species are the most popular shade trees in Ethiopia. The form
of their canopy is predominantly an umbrella-shaped.
Fodder and brows trees and their role in grazing pattern
Trees are perennial and deep rooted to grasses and crops. Most trees retain their green leaves in dry
seasons as they have access to resources like ground water in dry season incorporating trees into the
farming system there for complements grazing by providing fodder reserve to off-set deficiencies in
pasture supply.
Honey production
Ethiopia has three to five million bee colonies, which makes the country with the highest bee density in
Africa. It is the fourth largest wax producing country after China, Mexico, and Turkey. The total
estimate is about two thousand one hundred t/ year; it is one of the largest honey producing country in
Africa. Worldwide it stands in tenth place in honey production. In area where cattle production is
limited apiculture plays a significant role.
Recommended species
Flowering period
J F M A M J J A S O N D
Altitude(m)
1. Acacia abyssinica =============
1500 - 2900
2. Acacia albida
===============
````````````500 - 2600
3. Acacia tortilis
============
600 - 1900
6. Albizia gummifera ============
1550 - 2150
7. Albizia schimperiana===============
1550 - 2800
8. Cordia africana
====== = = == = = ======
550 - 2600
9. Croton macrostachys = = =========== = =
1300 - 2700
10.Dovyalis caffra ..._____________ ....................
1500 - 2600
11.Ehretia cymosa = ========== = = = = = = = = =
500 - 2700
12.Erythrina abyssinica ===========
======= 1
000 - 2800
13.Erythrina brucei ___
_______
1550 - 2800
14.E.camaldulensis===========================
900 - 2400
15.Eucalyptus globulus = = = = = ===== = = = = = == =
1800 - 3200
16.Euphorbia candellbrum ==
==========
1200 - 1900
17.Euphorbia tirucalli = = = = = = = = = = == = = = = = =
1300 - 2000
18 Moringa stenopetala
= = = = = = ==
19Phoenix reclinata
20. Vernonia amygdelina
21.Annual grases/Weeds
= in all ranges
______________________________________________________
Note:- It is a general indicator the detail and reliable information is under investigation for priority species in specific agro-ecology/site
condition/
============== Pollen and nectar are collected frequently
========
Pollen and nectar collected less frequently
________________ Either pollen or nectar
Pod production for livestock feed
Examples of Acacia tortilis pod
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Fodder from pollarded branches
Leaf harvested from Acacia albida pollarding 53 quintals /ha from Wolinchite, Butajira, Near Mojo and
Debre Zeit yielded 8.4 M3/year per hectare at the spacing of 50 trees/ha.
Site selection
It is a matching of a given site to an appropriate agroforestry species. In matching species to sites, a broad
climatic zone should be identified. This classified from subtropical humid to arid climate. Secondly
matching of the local conditions like altitude, slope, soil types, and local climate are important
information of the site on which agroforestry trees are planted. The other step is identification of the
detailed environmental requirements of the selected agroforestry tree. It is matching of species to site and
site to species that determines the suitability of species to site or site to the species.
Agroecology-based Agroforestry Application
In order to improve the agricultural production and thereby improve the livelihood of the population,
it is very important that the potential constraints of and the threat from degradation on the diverse
agro-ecological zones of the country be properly identified and understood. Once these zones are
recognized and characterized, on a scientific basis, it would be possible to categories the country into
homogeneous resource types. This will enable us to organize and develop scientific land use plans and
research networks as well as to identify strategies for resource conservation, development, and
utilization. Efforts have been made in the past to identify, classify, and characterize the agricultural
resources zones of the country. The Natural Resources Management and Regulatory Department in
the Ministry of Agriculture (MOA) has produced a map with a corresponding descriptive memoir
concerning the agro-ecological zones (AEZ) of Ethiopia. According to these documents, the country
can be categorized into 18 major AEZ and 49 sub-zones based on temperature and moisture regimes.
A summary of these AEZ and sub-zones, with particular emphasis to forestry:
•
•
•
•
•
Rainfall is intercepted by the canopy;
Humidity is high compare to open;
Sunshine hour intensity is low;
Soil under the tree is rich in organic matter; and
Despite low rain it receives moisture is high in dry season compared to open
In general, climatic and edaphic information that have been generated to characterize and used for
classification of agro-ecology is irrelevant to be used in agroforestry development.
Species Selection in Agroforestry
In agroforestry, species are selected based on their combined potential characteristics (genotypic and
phenotypic) in fulfilling the required characteristics in its direct or indirect role in agroforestry farming
system. Characteristics of a tree important in agroforestry are the following.
Adaptability
Native trees in a site of its natural state can be assumed that the species can be perfectly adapted to that
environment. Existing native trees are the best guides in selecting the adoptable tree species to the site.
This does not infer that the tree will meet the conditions required in farmers’ objectives. Most of the trees
can be shown to be relatively unproductive in their natural environment; however, manipulation of
conditions can greatly increase production. Adaptability in terms of objectives refers to the ability of the
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species to satisfy these objectives over a wide range of environment; environment is the result of many
factors, such as climate, altitude, soil status, management practices, existence of other plants and animals.
Growth rate
The major constraints that made tree farming as least accepted of all agricultural component are its long
rotation. Rapid growth, especially in early years, short rotation (period between planting and harvesting)
are considered desirable requirement in agroforestry trees. In its early growth due to availability of space,
production of grasses or crops can benefit farmers from agricultural returns. Rotation length varies greatly
with the species and intended objective of the end use of the agroforestry tree. The initial rotation of a
coppicing species is longer compared to its subsequent rotations. Faiderbia albida, Moringa stenopetala
and Eucalyptus camaldulensis can be an example of native and exotic species respectively.
Palatability as fodder
Nutritious and palatable species due to severe foraging pressure will often be grown very purely.
Controlled provision in a form of cut and carry or pollarding trees beyond the reach of the tallest animal,
as it is traditional practiced in Faidherbia albida tree-intercrop is an optional alternative.
Ability to withstand adverse condition
Establishment of agroforestry is preferred on open pasture or cropland that is devoid of trees. As it is not
a natural tree habitat, it is a site under highly adverse condition in most measures. The shock of planting,
exposure to hot and cold wind, accidental grazing, and drought and frosts stress, particularly in early
years can kill many trees. Some species can overcome such conditions and exhibit an incredible
performance. Suitable species selection, which is coupled with appropriate management, will improve
establishment and the subsequent productivity.
Growth habit
An agroforestry tree growth habit is depicted its branching and rooting characteristics. Important points to
be considered are:
•
•
•
•
shape of the crown;
crown density with respect to light penetration;
depth and spread of the root system; and
variation with the environment in which the trees are growing
Forms of growth of trees in an open is often poor, with excessive branches development and reduced
height growth. Thus, need to be carried out to maintain both wood quality and high light level to
agricultural crops. Even if eucalyptus shed large portion of their branches and Faidherbia albida almost
all its leaves, there is a need for pruning as most of the cereal crops are light demanding (c4 crops).
Among the exotic Eucalyptus, camaldulensis can be integrated with pasture or arable while Eucalyptus
globulus is a vigorous competitor due to its shallow and laterally spreading root nature. Traditional
windbreak management options like digging a trench between the tree and inset (main crop) along the
planting in the Gurage highlands seem to alive ate the problem.
Crop and livestock sheltering attributes
Trees that form not completely heavy crown density minimize competition with main crops and grasses.
Persistence of living branches to the base of the tree will insure provision of a uniform wind breakage on
its entire height. For shade requirement a clear bole either from an inherent self-pruning nature or from
pruning management, is important with its healthy growth of the entire tree. The shadow casted by such
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trees moves with the sun by leaving no area in the permanent shade. The air space between the canopy
and the animals allows unimpeded radiation of body heat and cooling by unrestricted air movement.
Trees' capability to withstand management practices
In general, many of the agroforestry systems demand extensive pruning and lopping to maximize harvest
of tree products. In such management practices, trees must be able to withstand the subsequent advice
effect such as dramatic restriction in growth rate and induced decaying and loss of quality. An ideal
fodder tree that suits such purpose are often directly grazed. Example of such trees is tree lucerne or
Tagasaste, Chamaecytisus palmensis, Luecaena spp. Ehretia sp., Acacia spp. and Vernonia amygdalina.
These species appear to thrive after grazing with increased potential production.
Vigor and productivity
Individual trees phenotype and its result of interaction between its genetic makeup will determine is
character. Due to natural out breeding there are chances both outstanding and very poor genotype.
Selection of the best genotype that is developed from cutting in its proper sites under appropriate
management can increase productivity. On the other hand, lack of genetic variability is risky because of
disease treat.
Nutrient cycling and nitrogen fixation
Soil nutrient in Ethiopia is lost in several ways. The major causes that is widely accepted is removal or
displacement by water namely soil erosion by water and leaching. The nutrient content of Eucalyptus
saligna was the highest in the leaves compared to nutrient content of other parts. This species is one
of the four common Eucalyptus species in Ethiopia and is closely related to Eucalyptus grandis. They
are also hybridized based on most field observations. Eucalyptus camaldulensis and Eucalyptus
globulus are the most dominant species in Ethiopia. With the assumption that the proportion of
nutrient content follows similar trend it is clear that the leaves and the branches have the highest
share. Since fine poles are harvested at the stage of fine branches, where wood is sold (exported) and
leaves are burnt (major elements lost except K, which has little demand to a farm). As most of the
wood for cash and fuel is from Eucalyptus source, the total nutrient exported (lost from farm) can be
determined. House construction is generally from Eucalyptus. In the south, they use fine poles to
make arc shaped traditional house that lasts for nearly a generation. Compared to consumption for
fuel and sell it is very small per given time. In all Eucalyptus, species the branch mass decreases with
age for example Eucalyptus grobulus at age of 30.7 years at Holetta at stocking rate 1028 stems/ha
has 496 tons of wood and 14.4 tons of branches. At Makanisa at the age of 5.4 the wood masses is 40
t/ha; while the branch is 6.2 tons. Thus in Makanisa the branch mass is 16 % compared to wood mass
while in Holetta it is less than 3 %. In Oromiya and the Southern Region Nation and Nationalities, it is
harvested at age of 3-7 depending on management and site conditions. Thus, the nutrient loss will be
very high showing the negative implication on soil nutrient output.
Nutrient uptake
Tree roots normally penetrate deeper in to the soil than the roots of crops. It has been assumed that trees
are more efficient than crops in taking up nutrients released by weathering deep in the soil. Phosphorus
and micronutrients are essential for plant growth and these elements are often released through such
weathering. The nutrient uptake from deep layers of the soil, sometimes called nutrient pumping, has still
not been experimentally verified. Nutrients from the atmosphere: The presence of a tree reduces wind
speed and creates good conditions for the deposition of dust. Nutrients in the atmosphere are conveyed to
the soil when they are dissolved in rain or settled with dust. Rainwater dripping from leaves and flowing
along the branches carries nutrients to the ground with those released from the tree itself, and associated
264
plants growing on it. It is known that the amounts of nutrients reaching the ground this way are
substantial. Protection from erosion: Soil erosion can be controlled by checking the flow of water down a
slope with runoff barriers- the barrier approaches-or through maintaining a cover of living plants and
litter. Agroforestry trees can recycle nutrient leach down through soil profile and minerals released from
weathering parent material such as rocks and sediments. Desirous trees that shed their leaves are more
important in recycling. Eucaluptus camaldulensis that has been scattered on grazing land was found to
recycle N, K, Ca and Mg from sub soil. Many species of eucalypt and hard wood have the ability to
internally cycle nutrients from dying leaves and twigs. These trees do not fix nitrogen. There are several
deciduous trees, like Ficus spp., Cordia africana and Croton macrostachyus that recycles nutrient, but do
not fix nitrogen on farmers' field. These trees are intentionally left on farm for soil impoverishment under
traditional practice. Grain and straw yield of Finger millet increased under Croton macrostachyus
compared to outside canopy at 14 meters distance. At the base of the tree 0-2.8 m, the yield depression is
15 and 41 percent for straw and grain respectively. At 6m, the increase was 61 and 44 while at 10m it is
12 and 0 percent. 14m distance in the open is considered as an open and control from preliminary test
there in an increase in P level under the tree yield was assessed where farmers did not use any fertilizer.
Table 4.3. Content of essential elements of Eucalyptus saligna
grown in the tropics, Brazil.
Component
Leaves
Branches
Bark
Wood
Litter fall/year
Litter
Total
Leaves & Branches (%) *
Elements essential for tree growth
(kg/ha)
N
P
K
Ca
Mg
108
7
61
64
17
30
3
45
69
7
13
2
26
57
13
21
12
42
17
6
42
24
41
44
12
63
3
20
100
15
277
51
325 351
70
88
73
52
77
73
Source Eucalyptus Dilemma 1988
* Liter fall and litter are considered as branches there might be
some bark that falls to the ground.
Spatial Arrangements for Trees in Agroforestry
In terms of agroforestry, trees can naturally exist or be planted in farms Natural trees are often scattered
because of selective clearing on previous forests and are usually uneven aged. Planted trees can be
indigenous or exotic and they are intentionally planted to meet specific agroforestry objectives. They
have generally some regular pattern in arrangement and are an even aged. Zonal arrangements in the form
of patterns are naturally grown trees that are displaced in between farms. Structurally they are all thinned
and as a result, they allow enough light for under-growth of grasses or other crops in a mix. Planted trees
are regular blocks and are in aligned arrangement such a boundaries, windbreak fences etc. The following
are the major tree arrangements in an agroforestry system.
Alley cropping (hedgerow)
Planting and managing of woody plants by mixing with annual crops in a linear arrangement is called
alley cropping. The trees are planted in an alley while the crops can be planted as an alley or broadcasted.
Woody plants are regularly cut and leaves and twigs are mulched in between tree row to suppress weed,
conserve moisture, and add nutrient and organic matter to the soil. The objectives are to increase crop
production and sustainable short rotation wood supply in form of fuel wood, smaller poles fodder and
other wood products.
265
Improved fallow
A management practice of leaving cropped field without cropping. The process allows the soil to rest
recover some of its fertility. Traditionally longer fallow periods can be possible if land availability is not a
limiting factor. Shorter fallow period practiced because of land shortage/population increase cannot
sustain subsequent crops production as it fails to restore the soil sufficiently. In southern Ethiopia, there
are quiet large proportions of highest density both in human and animal population. Thus, fallow based agroforestry is one of the options to minimize the problem. Potential species to be planted are short
rotation bushes with the highest nitrogen fixing ability. Forexample,. Tree lucerne (alley cropping)
Sesbania sesban, Sesbania grandflora etc. In rain forest areas where shifting cultivation is practices and
large portion of forest are cleared, these system minimizes the rate of forest destruction.
Boundary planting and live fence
It is a tree planting arrangement on a property or land use. It could be along boundaries of farm, home
compound, pasture, crop land etc. any line planting specially in a single row can be planted in much
closer spacing than block planting. Since there is a free space on both sides of the line, tree competition
limited to two sides only. It can also be planted in several lines. Gravillea robusta, Eucalyptus
camaldulensis Erythrina sp. Gravillea robust, Casuarina sp. Albezia lebbek and Euphorbia sp. are some
of the common boundary planted tree species. Line planting along the property affects more than one
owner. Non-owner can be benefited in terms of shade and shelter if the tree has other advantages like
nitrogen fixing. In such regard, it could be an advantage to get a benefit without encouraging labor or
other input. In most parts of Ethiopia where Eucalyptus globulus is planted, there is an effect of yield
depression in such planting, thus, the owner need to agree in advance with his neighbor. Living fence
developed from bigger cutting or seeds. It is living walls of vegetation from livestock enclosures and
pathways to protect croplands and pasture from moving animals (both domestic and wild). In most
African countries, living fence is used to protect a community against aggressive neighbors and foreign
invaders. Free grazing is common in any region especially in dry season. Most of the perennial
vegetation, fruit, or other crops like coffee can easily be browsed or can be damaged for no apparent
reason by animals. In a controlled rotational grazing padlocking, is an essential management component
in livestock eager. In the highlands - Erythrina spp., Euphorbia sp. and in lowlands Adhatoda
shemperiana, Comiphora species, Agave spp., Euphorbia tirucalli are grown traditionally. Most of the
above species develop from cutting.
Live-fence role in rangeland Paddocking
The major land use constraint, which is the root cause in land degradation that consequences poverty and
famine in animal production conventional practice is raring of large number of livestock beyond the
carrying capacity of the rangeland coupled with free grazing. Establishment of the following live-fence in
their respective agroecology mostly from cuttings of the plant part that divides the whole paddock into
four compartments will enable rotational grazing in a rangeland. This practice of dividing the land into
paddocks is worldwide-approved practices that sustain fodder and allow the grassland to heal after
overgrazing.
Windbreak
•
•
•
Sheltering of exposed site in high wurch agroecology to wind;
Protecting land from soil erosion and desiccating wind; and
Sheltering crop and animal land from desiccation and protect soil erosion
Live fence
Biological structures against livestock and human interference can be constructed by planting closely
spaced trees or shrubs on farmer’s property. Free grazing is the major causes for land degradation and
subsequent poverty in Ethiopia in general.
266
•
•
•
•
•
Factors to be considered in species selection are ability of keeping off livestock and human through bearing
thorns and dense branches;
Easy to establish and maintain;
Ability of withstanding temporary water logging;
Resistance to fire, for example Comphora sp. in dry area where frequency of fire is high in rangelands; and
Provision potential of by-products and other indirect services
Benefits
•
•
•
Fencing field makes paddock, around house, fodder bank and woodlot management practice and sustainable
utilization possible;
Live fences is permanent cheaper to maintain ones it is established; and
Live fence can give products like fodder, fruit or vegetables(Moringa stenopetala)
Tree intercrop
Tree in a cropland is selected based on complementary relationship with the main crop. If it is important
and competitive, appropriate management system is applied to minimize its detrimental effect on the
main crop.
Management of Trees in Agroforestry
The major role of tending operation in agroforestry is restoration of health co-existence among integrated
crops of a given land use system. Because woody perennial usually have well structured and strengthened
rooting an branching systems as compared to other adjoining systems, the negative influence comes from
tree and shrubs.
Pollarding
•
•
•
•
It is removal of the crown total;
Pollarding occurs when the adjoining crop is in its pick growing period;
It helps the adjoining crop by removing the shading effect; and
It is usually practiced in Agrisilviculture and agrisilvipasture systems.
Pruning
It is an act of removing the branches wood perennial close to the stem and roots of woody perennial.
•
•
•
•
•
Pollarding can be exercised after the woody crop develop coppcing stem. In free grazing areas branches are
pruned beyond the animal reach like in the Case of Acacia albida tree enter-crop. Such management practice
enables farmers to provide fodder depending on the need;
Pruning is practiced in all AF systems;
Sside pruning is practiced to maximize term growth, facilitate access to a passerby, and reduce competition for
light and moisture against adjoining crops;
It is better practiced when the branch basal diameter is no exceeding l inch; and
Pruning cuts are close to the stem and it is worth doing for quality tree species.
Thinning
It is reduction of stock density to an optimal level.
•
•
Low thinning (German Method); and
High thinning (French Method)
Lopping
It is removal of portion of branches of woody perennial. It may be practiced in AF systems.
267
Characteristics of a tree important in agroforestry
•
•
•
•
•
•
•
Adaptability;
Growth rate;
Palatability as fodder;
Growth habit;
Crop and livestock sheltering attributes;
Trees' capability to withstand management practices; and
Vigor and productivity
In rural land scope tree perform the following functions
•
•
•
•
•
•
•
Reduce ground level wind velocity so reducing losses of soil moisture and soil drift when trees are
planted/retained as wind break;
Reduce rain drop intensity, thus reduces primary cause of soil erosion by water;
Increase infiltration, reduce run off and surface erosion and subsequent lake siltation and death;
Provision of high level of fresh organic matter supplied as leaf and bark litter promotes soil aggregation, which
in turn, decreases the susceptibility of the soil erosion;
Tree roots bind the soil together, strengthening and consolidating the immediate area reducing soil movement;
Trees restore the hydrological balance of the hydrological cycle from environmental conservation viewpoint;
and
Trees can combat salinity. The presence of deep-rooted trees reduce salty water table down, while the removal
of trees and replacement with Shallow rooted crops of pasture will increase the volume of water recharge to the
ground water. It results in salt-water rise to the surface and causes salinity.
Agroforestry Planning, Monitoring and Evaluation
Extension or current scaling up can be described as non –formal education system aimed at improving
livelihood of the rural people based on the willingly involvement on forestry(agroforestry) activities.
In such two ways, learning the task is not an entire helping of people to plant trees but is a combined
technical, psychological, sociological, institutional, and political task. The flow is more complex and is a
two way, this is presented in one-dimensional simple flow to give a high light. Such process in integrated
development unit in Chilalo Agricultural development Unit (CADU) was the only successful project of
its kind in the last 20 to 30 years in Africa Rural development history. The writer of this manual is a
member of the institution as a senior extension agent and later as an assistant researcher in forestry. In
former CADU Rural Development Package, the project is lead by the project director. The planning and
evaluation department is monitors every activity according to the plan proposed. All the departments
coordinate their activity through extension and Research link. The task at Development district will be
integrated and carried out under same person who is head of the center with a qualification of college
diploma in general agricultural or equivalent. The structure is as follows (decentralized management
system). All the illustrated department, division, and sections are under the project direction directly and
are evaluated and monitored by the planning and evaluation department, which as its own professionals
that assesses the asset created and check against the set benchmark in each development centers and
against the planed and or modified sets of activities. Promotion of any staff is based on the output and
level of development directly or indirectly achieved by the target farmers. Field Supervisors and
coordinators or the project director can be evaluated on an open meeting at every level if he or she is
believed unfit or low in performance; they will be subjected to automatic dismissal or warning. It was a
real democratic institution where there is good management accountability, transparence to poor farmers
and bosses and thus, one deserves promotion based on his/her out come. Continuous feedback
information is the basis and adopted culture for improvement of the quality of the work and output of the
project.
268
Identifying Important Farm Trees and Shrubs
Some of the tree species in the sites visited have not been properly identified. Such problems also
exist in the institutions that supply the seeds and reference books that are meant to provide such
information services. Nevertheless, relatively reliable and accurate information is available, and can
be obtained, at the Addis Ababa University Herbarium set up under the Ethiopian Flora Project.
However, there is still some limitation even in the reference materials like Eucalyptus species
illustration, Acacia species for example Acacia decurrens and Acacia mearnsii were described as
glandless and a possessor respectively on their leaf. Naturally, both species are distinguished by
possessing gland on their rachis. This character is both the simplest and major distinguishing character
in identification of some species of the Genera of exotic species. Thus, it has been much simplified
and illustrated in this manual. In some instance, the specimens were not collected or drawn, and as a
result, species, subspecies, or provenance variation has not been clearly established and distinctly
indicated. This type of misinformation can adversely affect the appropriate selection of species for the
desired output .Due to hybridization, there are obvious identification problems that can arise and the
source for this confusion is ambiguous and either at the national and /or international level. Some of
the most common areas of confusion regarding the agroforestry species in the different project sites
visited are listed in the following table. Till the detail manual is published the most common and
serous confused few species have been prioritized in this document and illustrated with major and
distinct simplification features side by side on same page. Illustrations are simplified and focused on a
very distinct character that enables even non-technical person to differentiate one species from the
other. Confusion in most cases is created due to very close similarities of the species. Thus, it is hoped
that large target population, which need the knowledge, can be reached in a very short time through
simplified and self-explanatory illustrative identification field guide by mere comparison of the
illustration focusing on the indicated part of the illustration.
Aca
Acacia abyssinica
Local Name :Omoneyena(kis);mugaa /mugunga(kik)
Acacia nigra
Pods: brown, 6-12,5x(1,2) 1,7-2,8cm,oblong,
Seeds;8-10x5-6mm,compressed;areole+6,5x4mm.
∗Pod elliptical, flattened
Flower white (red in bud)
Seed 7-10x4-6mm
Flower pink white
Seed 8-10x5-6mm
Remark several similar acacias such as Acacia sieberiana,Acacia nigrii etc are confused with Acacia abyssinica and its different sub
species. Currently Acacia nigrii is selected as a prior confused species with Acacia abyssinica. The rest will be considered in the second
edition.
Acacia tortils
sub sp. spirocarpa
Acac Acacia senegal
Pods: Yellowish, grey-brown to brown ,
papery ,with
∗ Thorn(curved back at the middle and
forward at the edge)and pod wide and
normal
∗ Thorn strait and coiled pod
Flowers white or pale
Seed 4-7x306mm,elliptic
Flower –white
Seed 8-12 (sub-circular
Remark The two species are the most common and economically important dry land species. Acacia Senegal refuges harsher environment
than Acacia tortils.
269
Balanites aegyptiaca
Fruit: red,ellipsoid,28-45 by 12-25mm
Balanites arbicularis:
Fruit :orange ,ellipsoid ,2-3 .5 by 1.8-2.8cm.
.
∗Flower yellow green
Seed 4x2cm
Fruit and leaf
∗Flower green yellow
Seed 2cm(rounded)
Fruit and leaf
Albizia schimperiana:
∗ Leaf normal shape
Flower white
Fruits 25cm long,3.5 cm wide
Albizia gummifera
∗ Leaf (rectangular ,mid rip Diagonal)
Flower white pink cluster
Fruit 20cm long ,2cm wide
Erythrina brucei
Growth form: Tree up to 15-20m tall;
branches prickly.
Leaflet: elliptic to ovate or obovate ,up to
23x16cm,acuminate at the tip ,
∗ Leaf (Tip Pointed)
Eryth Erythrina abyssinica
Leaves: Leaflet broadly ovate ,rounded or
∗ Leaf(tip indented pod constricted
Pod 4-16 cm strongly constructed seed 1-10,
red with hilum)
Pod up to 15cm long (linear –oblong) seed 2-4
,red with white hilum
Remark Erythrina burana etc will be included in the second edition
Dodonaea angustifolia
Dodonaea angustifolia variety viscosa
∗Flowers 2 papery wing
∗Flowers yellow green
Fruits 3cm across with 3 papery wing as
shown with the leaves
Remark Specimen for Dodonaea viscos variety viscosa is not available the illustration is drown from the description. Thus, a reader
should use the information with this limitation in mind. The number of wings is not always the ones one can see on illustration, it is the
number one mostly finds in the respective subspecies.
270
Acacia decurrens
Acacia dealbata
∗Leaves: - grayish –green Gland: found at
the base of each pair of pinnae
(there are 8-20 pair of pinnae)
∗Leaves –green Gland :found at the base of
each pair of pinnae
(there are 5-12)pair of pinnea)
Remark The gland arrangement and correlation with the pair of pina is the same.
The leaf Acacia decurrens is green while that of Acacia dealbata is silver white.
Acacia Acacia mearnsii
Acacia decurrens
∗Leaves –dark green
∗Leaves –green Gland :found at the base of
each pair of pinnae (there are 5-12)pair of
pinnae)
Gland: numerous and irregular (there are 920pair of pinnae)
Remark The above two species are usually hybridized. Thus, one can see the intermediate character in terms of gland arrangement and
number. Thus care bust be taken in identification, as these two species are the most confusing. Acacia decurrens refuges higher elevation
comparatively.
Casuarina cunninghamiana
Casuarina equestifolia
∗Leaf teeth lower in number than Casuarina
cunninghamiana
∗Leaf –teeth whorls of 6-8 for seedling and 810 in adult.
Remark Casuarina equesitifilia is a costal plant. The species we conventional call as Casuarina equesitifolia is mostly Casuarina
cunninghamiana.
Leon costermans
271
Eucalyptus camaldulensis
∗Fruit :Pedicellate, truncate-globular value
most of the time 4 sometimes 3or 5
Opercula: Hemispherical, Conical etc
Eucal
Eucalyptus tereticornis
Value most of the time 4and sometimes 5
Opercula: Horn shaped or conical
Remark In Ethiopia most Eucalyptus camaldulensis is not a true to type .It is suspected to be a hybridized with Eucalyptus teriticornis.
The presence and absence of lignotuber will also determine the coppicing ability after fire. Those with lignotuber performs better after fire.
Currently local farmers are practicing stump burning as a best management tool for the production of fast growing and strait poles of high
market value.
Eucalyptus saligna
∗Value 3or 4
(erect or protruding just above rim level)
EucalyEucalyptus grandis
∗Value 4 or relatively broad, exerted and incurved
Remark This two species are mixed their agroecology is different. Eucalyptus grandis(great) naturally grow on river bank and deep soil. It
is commonly known as Swamp Gun, a name derived from its natural habitat while Eucalyptus lanigna is on upland thus knowing which one
is which is very essential.
Melia azadrachta
Azadrachta Indica(tree neem)
∗Leaves –bipinnate, Upper leaf dark green,
lower leaf faded green
∗Leaves -pinnat
Remark These are false and true Neems Azadrachta which have always been confused. The true neem is a low and dry land habitat
comparatively.
272
Moringa oleifera
Leaves: 2-3(4) –pinnate ,glandular near
petiole and petiolules,6.5-60cm long
;pinnae4-6 pairs ;leaflets 6-9(11) per
pinna, elliptic or obovate ,base rounded or
cuneate, apex rounded or emarginate
,0.5-2(3)by o.3 –1.3(2)cm .
Moringa stenopetala
Leaves: 2-3pinnate,glabrous or pubescent to55cm long;
pinnae ca.5 pairs ;leaflets3-9 per pinna, ovate or elliptic,
base rounded or cuneate ,apex acute ,3.3-6.5 by 1.83.3cm.
Leaves apex-round
Seeds winged spherical
Leaves :apex-pointed
Seeds winged elliptic-tregonous
Trees of Kenya Noad T. and Anne Birnie 1989
4.2. Irrigation Water Management
All plants require water, air, light, and media to survive, grow and reproduce. The soil acts as a media
and gives stability to the plant, stores water, and nutrients that the plants can take up through their
roots. The sunlight (light) provides the energy, which is necessary for plant growth and
photosynthesis. The air allows the plants to "breath". Water is needed for photosynthesis, respiration,
absorption, translocation, and utilization of mineral nutrients. Without water, crops cannot grow. Too
much water is not good for many crops either. Apart from paddy rice, there are only very few crops
which like to grow "with their feet in the water.” If there is too much water in the soil, there will not
be enough air. The excess water must be removed. If there is too little water in the soil, it must be
supplied from other sources. Therefore, adequate water supply is important for plant growth. The
most well known source of water for plant growth is rainwater. When the rainfall is not sufficient, the
plants must receive additional water from other sources. It may be provided partially or entirely by
artificial means called Irrigation. The process by which irrigation water is controlled and used in the
agricultural production is called Irrigation Water Management (IWM). IWM requires determining the
time to irrigate and amount of water to apply in each application. In IWM practices, certain skills and
organization forms are used to control physical, biological, chemical, and social resources to provide
water for farms and crops for improved production.
Crop Water Requirement
Water requirement is the total quantity of water, regardless of its sources, required by the crop in a
given growing season (from the time it is sown to the time it is harvested) for compensating the
evapotranspiration loss plus water used for digestion, photosynthesis, transportation of minerals and
foods, and also for structural support. The plant roots extract the required water from the soil.
Evaporation, Transpiration, Evapotranspiration, Crop Evapotranspiration and
Crop consumptive Use
The main part of the water does not remain in the plant, but escapes to the atmosphere as vapor
through the plant's leaves and stem. This process is called transpiration, T. Transpiration happens
mainly during the daytime. Water from an open surface escapes as vapor to the atmosphere during the
day and the same happens to water on the soil surface and to water on the leaves and stem of a plant.
This process is called evaporation, E. The combination of the two separate processes, namely;
evaporation and transpiration is referred to as evapotranspiration, ET. Therefore, the crop water
273
requirement, ETcrop is also called crop evapotranspiration. The water transpired by the plant leaves
and evaporated from wet surfaces plus water used for other processes (digestion, photosynthesis,
transportation) is generally referred to as crop consumptive use, CU. Thus, CU exceeds ETcrop by the
amount of water used for digestion, photosynthesis, transportation etc. Since this difference is usually
less than one percent, ETcrop and CU are normally assumed equal. Therefore, crop water
requirement, crop evapotranspiration, and consumptive use are used interchangeably. The water
requirement of a plant is usually expressed in mm/day, mm/month, or mm/season. Suppose the water
need of a certain plant in a very hot, dry climate is 10 mm/day. This means that each day the plant
requires a water layer of 10 mm over the whole area on which the plant is grown. It does not mean
that this 10 mm has to be supplied by rain or irrigation every day. It is, of course, still possible to
supply, for example, 50 mm of irrigation water every 5 days. The irrigation water will then be stored
in the root zone and gradually be used by the plants.
Factors affecting ETcrop
The water requirements of plants varied with the plant species and varieties, length of growing season,
plant growth stages, and climate.
Climate factors affecting ETcrop
A certain plant grown in a sunny, dry humidity and windy climate needs per day more water than the
same plant grown in a cloudy and cooler climate. When it is dry, the crop water requirement is higher
than when it is humid. In windy climates, the plants will use more water than in calm climates. The
time of the year during which crops are grown is also very important. A certain crop variety grown
during the cooler months will need substantially less water than the same crop variety grown during
the hotter months. Climatic factors, which influence the plant water requirement, are shown Fig. 5.5.
Fig. 5.5. Major climatic variables affecting ET
Crop type affecting ETcrop
Maize requires less water than cotton and more water than onion. Moreover, fully-grown maize will
need more water per day than a fully developed onion. Shorter duration plants require less water than
longer duration crops. Table 1 gives some Indicative values for the duration of the total growing
season and the crop water requirement for the various field crops. There is a large variation of values
not only between crops, but also within one crop type. It should, however, be noted that these values
are only rough approximations and it is much better to obtain the values locally. In general, it can be
assumed that the growing period for a certain crop is longer when the climate is cool and shorter when
the climate is warm.
274
Growth stages affecting ETcrop
The duration of the total growing season has an enormous influence on the seasonal crop water
requirement. Fully-grown maize will need more water than at early and late growth stage of the same
plant. As has been discussed before, the crop water need or crop evapotranspiration consists of
transpiration by the plant and evaporation from the wet surface. When the plants are very small the
evaporation will be more important than the transpiration. The ETcrop increases gradually from crop
development stage to the beginning of mid-season. The maximum crop water requirement is reached
at the end of the crop development stage, which is the beginning of the mid-season stage until it
reaches repining stage. When the plants are fully-grown, the transpiration is more important than the
evaporation. The ETcrop also gradually declines from the end of mid season stage which is the
beginning of the ripening stage till maturity (Figure 2).
Table 4.4. Indicative values of total growing season and crop water requirement
Crop
Alfalfa
Banana
Barley/Oats/Wheat
Bean green
Bean dry
Cabbage
Carrot
Citrus
Cotton
Lentil
Maize grain
Millet
Total growing
period (days)
100 – 365
300 – 365
120 – 150
75 – 90
90 – 120
100 – 150
100 – 150
240 – 365
150 – 180
150 – 170
100 - 180
105 – 140
Seasonal
ETcrop (mm)
800 – 1600
1200 – 2200
450 – 650
300 – 500
300 – 550
350 – 500
900 – 1200
700 – 1300
300 – 500
500 – 800
450 – 650
Crop
Onion
Groundnut
Pea
Pepper
Potato
Rice
Safflower
Sesame
Sorghum
Soybean
Sugarcane
Tomato
Total growing
period (days)
135 – 175
130 – 140
90 – 120
120 - 150
105 – 150
90 – 150
120 – 160
90 - 180
100 – 140
100 - 150
270 – 365
90 - 180
Seasonal
ETcrop
(mm)
350 – 550
500 – 700
350 – 500
600 – 900
500 – 700
350 – 700
600 – 1200
600 – 800
450 – 650
450 – 700
1550 – 2500
400 – 600
Fig. 5.6 Plant growth stages
Estimation of crop water requirement
Crop water requirement is estimated from the following relationship:
275
ETcrop = ETo x Kc
Where, ETcrop is the crop water requirement in mm day-1, ETo is the reference ET in mm day-1 and
Kc is the crop coefficient.
The reference evapotranspiration, ETo, is a climatic parameter expressing the evaporating power of
the atmosphere when water is abundantly available. This concept was introduced to know the
evaporative demand of the atmosphere independent of crop type, crop development and management
practices. Therefore, the only factors affecting ETo are climatic parameters and can be computed from
weather data. The FAO Penman-Monteith method is recommended as the sole model for determining
ETo. Indicative values of ETo for different agro-climatic regions is given in Table 2.
Crop coefficient reflects the effect of crop on crop water requirement. The changing characteristics of
the crop over the growing season affect the Kc-values. The Kc-values for major crops at different crop
growth stages is given in Table 3. If ETcrop is known and Kc could be computed from the following
relationship:
Kc = ETcrop
ETo
Table 4.5. Indicative values of reference evapotranspiration for different agroclimatic regions
100C
(cool)
200C
(moderate
30oC
(warm)
Humid
Sub humid
Semiarid
Arid
3–4
3–5
4–5
4–5
4–5
5–6
6–7
7–8
5–6
7–8
8–9
9 – 10
Humid
Sub humid
Semiarid
Arid
3–4
3–5
4–5
4–5
4–5
5–6
6–7
7–8
5–6
6–7
7–8
10 – 11
2–3
3–4
3–4
4–5
5–6
6–7
5–6
7–8
10 – 11
2–3
3–4
3–4
5–6
5–7
8–9
Regions
Tropics
Subtropics
Winter rainfall
Humid – sub humid
Semi-arid
Arid
Temperate
Humid – sub humid
Semiarid - arid
Table 4.6. Range of Kc values for different crops and at different growth stages
Crop
Banana
Barley/Oats/Wheat
Beans Dry
Green
Cabbage
Cotton
Groundnut
Maize
Onion
Pepper
Potato
Rice
Initial
0.4 – 0.5
0.3 – 0.4
0.3 – 0.4
0.3 – 0.4
0.4 – 0.5
0.4 – 0.5
0.4 – 0.5
0.3 – 0.5
0.4 – 0.6
0.3 – 0.4
0.4 – 0.5
1.1 – 1.15
Crop development stages
Development
Mid-season
0.70 – 0.85
1.0 – 1.10
0.70 – 0.80
1.05 – 1.20
0.70 – 0.80
1.05 – 1.20
0.65 – 0.75
0.95 – 1.05
0.70 – 0.80
0.95 – 1.10
0.70 – 0.80
1.05 – 1.25
0.70 – 0.80
0.95 – 1.10
0.70 – 0.85
1.05 – 1.20
0.70 – 0.80
0.95 – 1.10
0.60 – 0.75
0.95 – 1.10
0.70 – 0.80
1.05 – 1.20
1.1 – 1.5
1.1 – 1.3
276
Late season
0.90 – 1.0
0.65 – 0.75
0.65 – 0.75
0.90 – 0.95
0.90 – 1.0
0.80 – 0.90
0.75 – 0.85
0.80 – 0.95
0.85 – 0.90
0.85 – 1.0
0.85 – 0.95
0.95 – 1.05
Safflower
Sesame
Sorghum
Sugar cane
Tef
Tomato
0.3 – 0.4
0.3 – 0.4
0.3 – 0.4
0.4 – 0.5
0.3 – 0.4
0.4 – 0.5
0.70 – 0.80
0.70 – 0.80
0.7 – 0.75
0.70 – 1.0
0.70 – 0.80
0.70 – 0.80
1.05 – 1.20
1.10 – 1.20
1.0 – 1.15
1.0 – 1.30
0.9 – 1.10
1.05 – 1.25
0.65 – 0.70
0.70 – 0.85
0.75 – 0.80
0.75 – 0.80
0.65 – 0.75
0.8 – 0.95
Irrigation Requirement, IR
Irrigation is generally defined as the artificial application of water by human being to soil for
supplying the moisture essential for plant growth and production. The total amount of water that must
be supplied by irrigation during the crop growth period is termed as irrigation water requirement
(net, IRn). The irrigation water requirement of a certain crop is, therefore, the difference between the
crop water need and that part of the rainfall, which can be used by the crop (the effective rainfall).
Mathematically it can be expressed as:
IRn (mm) = ETcrop (mm) – Effective rainfall (mm)
Suppose a tomato crop grown in a certain area has a total growing season of 150 days from February
to June. The rainfall incidence, as recorded from the meteorological station, and the ETcrop, as
predicted from certain model, are as shown in Table 4.7.
Table 4.7. Irrigation water requirement
Months
ETcrop (mm/month)
Rainfall: P (mm/month)
Effective rainfall: Pe (mm/month)
Net-irrigation water requirement, IR n(mm)
Feb
69
20
2
67
Mar
123
38
13
110
Apr
180
40
14
166
May
234
80
39
195
June
180
16
0
180
Total
786
194
68
718
Irrigation water requirement for the tomatoes can be calculated on a monthly basis and for the total
growth period as shown in Table 4. The total ETcrop of tomatoes over the entire growing season is
786 mm of which 68 mm is supplied by rainfall. The remaining quantity (786 - 68 = 718 mm) has to
be supplied by irrigation.
Irrigation efficiency
While transporting and applying water to the irrigated field, some wastage occurs. Water losses could
occur even in best irrigation water management. Thus, some losses of irrigation water are inevitable.
When computing irrigation requirement, an efficiency factor needs to be applied to account for losses,
therefore, gross irrigation requirement. The most important efficiency terms in connection with
irrigation are given below which are usually expressed as percentage:
Water conveyance efficiency, Ec. It is the ratio of the quantity of water delivered to the
fields/irrigated land to the quantity of water diverted into the canal system from the river or reservoir.
Ec ( % ) = Water delivered by the system X 100
Water introduced from the source
Water application efficiency, Ea, the water losses that occur during the application of irrigation
water to the field
Ea ( % ) = Water stored in the root zone X 100
Water delivered to the field
277
Water-Use Efficiency, WUE, the water beneficially used by the plant for producing crop
WUE ( % ) = Water beneficially used X 100 Or Yield produced by the plant (kg ha-1)_
Water delivered for the crop
Crop consumptive use (mm)
Irrigation Water Quality
The quality of irrigation water is judged by the amount of suspended and dissolved materials it
contains. All irrigation water contains dissolved or suspended materials. Suspended materials can be
removed with filters. Crop yield can be reduced significantly when the dissolved materials or salinity
of the irrigation water, is high enough. In some case, even though the salt content of the water is low,
continued irrigation application may gradually build up the salt content in the root zone. Nevertheless,
irrigation water quality is commonly assessed in terms of soluble salts content, percentage of sodium,
boron, and bicarbonates contents. High amounts of exchangeable sodium can cause soil particle
dispersion that reduces soil structure and restricts air and water movement into and within the soil.
Sodium, chloride, boron, and other ions are toxic to many plants when present in sufficient
concentrations. Table 4.8 indicates the classification of water quality for irrigation.
Table 4.8. Guidelines for evaluating irrigation water quality
Potential irrigation problem
Salinity: (affecting crop)
ECw\
or
TDS
Infiltration (affecting soil)
SAR = 0 – 3 and ECw =
= 3– 6
=
= 6 – 12
=
= 12 - 20
=
= 20 – 40
=
Specific ion toxicity
(affects sensitive crop)
Sodium surface
Sprinkler
Chloride Surface
Sprinkler
Boron
Miscellaneous effect
(affect susceptible crops)
Nitrogen
Bicarbonate (overhead sprinkling only)
pH
Units
Degree of restriction on use
None Slight to moderate Severe
dS m-1
< 0.7
mg lt-1
< 450
0.7 – 3.0
450 - 2000
>3.0
>2000
> 0.7
> 1.2
> 1.9
> 2.9
> 5.0
0.7 – 0.2
1.2 – 0.3
1.9 – 0.5
2.9 – 1.3
5.0 – 2.9
< 0.2
< 0.3
< 0.5
< 1.3
< 2.9
SAR
me lt-1
me lt-1
me lt-1
me lt-1
<3
<3
<4
<3
< 0.7
3–9
> 3
4 – 10
>3
0.7 – 3.0
> 9
me lt-1
me lt-1
<5
< 1.5
> 10
> 3.0
5 - 30
> 30
1.5 - 8.5
> 8.5
Normal range 6.5 - 8.4
Leaching requirement, LR
This is a fraction of the irrigation water applied and leached through the root zone to prevent the
build-up of salt and keep a favorable salt balance in the root zone. The LR can be computed from the
following relationship:
LR =
ECw
5ECe – ECw
Where, ECw is the salinity of irrigation water in dS m-1 and ECe is the EC corresponding to 90
percent yield potential in dS m-1 (Table 4.9).
278
The total quantity of water required to satisfy both ETcrop and LR to control soil salinity is equal to:
IRn
1 + LR
where IRn is the net irrigation requirement in mm
Table 4.9. Crop tolerance and yield potential of selected crops as influenced by irrigation water
salinity (ECw) or soil salinity (ECe)
Crops
Barley
Cotton
Sorghum
Wheat
Wheat, duram
Soybean
Groundnut
Rice (paddy)
Sugarcane
Maize
Bean
Tomato
Cabbage
Potato
Sweet potato
Pepper
Onion
Carrot
Alfalfa
Orange
Lettuce
100 %
ECe – ECw
8.0
5.3
7.7
5.1
6.8
4.5
6.0
4.0
5.7
3.8
5.0
3.3
3.2
2.1
3.0
2.0
1.7
1.1
1.7
1.1
1.0
0.7
2.5
1.7
1.8
1.2
1.7
1.1
1.5
1.0
1.5
1.0
1.2
0.8
1.0
0.7
2.0
1.3
1.7
1.1
1.3
0.9
90 %
ECe – ECw
10
6.7
9.6
6.4
7.4
5.0
7.4
4.9
7.6
5.0
5.5
3.7
3.5
2.4
3.8
2.6
3.4
2.3
2.5
1.7
1.5
1.0
3.5
2.3
2.8
1.9
2.5
1.7
2.4
1.6
2.2
1.5
1.8
1.2
1.7
1.1
3.4
2.2
2.3
1.6
2.1
1.4
75 %
ECe – ECw
13
8.7
13
8.4
8.4 5.6
9.5
6.3
10
6.9
6.3
4.2
4.1
2.7
5.1
3.4
5.9
4.0
3.8
2.5
2.3
1.5
5.0
3.4
4.4
2.9
3.8
2.5
3.8
2.5
3.3
2.2
2.8
1.8
2.8
1.9
5.4
3.6
3.3
2.2
3.2
2.1
50 %
ECe – ECw
18
12
17
12
9.9
6.7
13
8.7
15
10
7.5
5.0
4.9
3.3
7.2
4.8
10
6.8
5.9
3.9
3.6
2.4
7.6
5.0
7.0
4.6
5.9
3.9
6.0
4.0
5.1
3.4
4.3
2.9
4.6
3.0
8.8
5.9
4.8
3.2
5.1
3.4
0%
ECe – ECw
28
19
27
18
13
8.7
20
13
24
16
10
6.7
6.6
4.4
11
7.6
19
12
10
6.7
6.3
4.2
13
8.4
12
8.1
10
6.7
11
7.1
8.6
5.8
7.4
5.0
8.1
5.4
16
10
8/0
5.3
9.0
6.0
The Soil
Soil is a reservoir to store water needed by plants. It is heterogeneous mass and composed of mineral
particles and organic matter. Soils originating from degradation of rocks are called mineral particles.
Some originate from residues of plants or animals (rotting leaves, pieces of bone, etc.), these are
called organic particles (or organic matter). The soil particles seem to touch each other, but in reality
have spaces in between. These spaces are called pores. When the soil is "dry", the pores are mainly
filled with air. After irrigation or rainfall, the pores are mainly filled with water. Living material is
found in the soil. It can be live roots as well as beetles, worms, larvae etc. They help to aerate the soil
and thus create favorable growing conditions for the plant roots. The soil also stores nutrient, allows
the roots of plants to grow, and permits the withdrawal of water and nutrient during the plants growth
lifetime. However, the soil factors such as texture, structure, bulk density, depth of soil, infiltration or
intake characteristics, salinity and water retention characteristics influence farming.
Soil texture
The term soil texture refers to the size range of mineral particles in the soil. These minerals particles
are identified by the term ‘clay’, ‘silt’ and ‘sand’, which are defined as having the following
dimension in diameter:
279
Clay
Silt
Fine sand
Coarse sand
- less than
- between
- between
- between
0.002 mm
0.002 and 0.02 mm
0.02 and 0.2 mm
0.2 and 2.0 mm
The texture of a soil is determined mainly by its proportion of clay, silt, and sand content. A soil is
described as:
•
•
•
Sandy if it has more than 50 % sand and called coarse-textured soils;
Loamy if it has appreciable sand not more than 30 % of clay and called medium-textured soils; and
Clayey if it has more than 30 % of clay and less than 50 % of sand and are called fine-textured soils
To make clear distinction in texture, the percentage of sand, silt, and clay in a given soil is first
determined in a laboratory. Using the data, the texture group is determined by means of a chart called
textural triangle chart as shown in figure 3. The texture of a soil has a very important influence on the
flow of soil water, circulation of air and the rate of chemical transformations, which are of importance
to plant life. The farmer cannot able to modify the texture of the soil by any practical means.
Soil structure
Soil structure refers to the degree in which individual soil particles aggregate into groups. The
particles of coarse-grained soils tend to function as individuals, while the aggregated particles of fine
texture soils tend to form granules. The size and shape of these particle groups, and their stability is
defined as the soil structure.
Fig. 5.4 The soil texture triangle (from Handbook No. 436 U.S. Department of Agriculture,
Washington, D.C., 1975)
Structures are developed and improved by cyclic of wetting and drying, freezing and thawing
and combination of these conditions. Organic matter adds stability to the soil aggregate and
serves as a cushion against the effect of tillage. Excessive irrigation, plowing, or otherwise
working fine textured soils, when either too wet or too dry, tends to destroy the structure.
Favorable soil structure particularly in fine textured soils is essential to the satisfactory
280
movement of water and air. The permeability of soils to water, air and roots, provided by
favorable soil structure is equally important to crops growth as are adequate supplies of
nutrient. Some of the type of soil structure and their effect on drainage is shown in Figure 4.
The most favorable soil structures for agriculture production are usually prismatic, blocky,
and granular structures. Platy and massive structures, which are almost identical in their form,
impede the downward movement of water. Unlike soil texture, the structure of the soil can be
improved.
Granular
Blocky
Prismatic
Massive
Fig. 5.5 Types of soil structure and their effect on downward movement of water
Soil depth, D
The depth of soil in which to store satisfactory amounts of water should be given due emphasis.
Shallow soils require frequent irrigation water to keep crops growing. Deep soils of medium texture
and loose structure permit plants to root deeply, provide for storage of large volumes of /irrigation
water in the soil, and consequently sustain satisfactory plant growth during relatively long periods
between rain/irrigation. The volume of water actually absorbed by the same plant roots and consumed
to produce a crop may be practically the same for shallow and deep soils, provided the plants are
grown under the same climatic condition. Under irrigated condition, more water is required during the
crop growth season to irrigate a given crop on a shallow soil than is required for the same crop under
a deep soil. The larger number of irrigation required for shallow soils and greater unavoidable water
losses on shallow soils; account for the differences in water requirements for different soils during the
season.
281
Soil bulk density, BD
Bulk density refers to the soil overall density/compactness of a soil and should be distinguished from
the soil density of the solid soil constituents, usually called the particle density, which is
conventionally taken as 2.65 g cm3. The bulk density is computed using following equation:
BD (g cm3) =
weight of dry soil (g)
Volume of the same soil (cm3)
Soil porosity, n
Roots require oxygen for respiration and other metabolic activities. They also absorb water and
dissolve nutrients from the soil, and produce carbon dioxide, which has to be exchanged with oxygen
from the atmosphere. This aeration process requires open pore space in the soil. If roots are to develop
well, water plus nutrient and air must be available simultaneously. The soils contain small pores
(micro-pores) and large pores (macro-pores). The small pores are used for the storage of water and the
large pores are used as channels for the exchange of air and for spaces, while fine textured soils
(clays) have a greater percentage of total pore space. The soil pore space could be computed from:
n ( % ) = 100*(1 – BD (gm cm3) )
PD (gm cm3)
Soil Water
Plant growth is determined to large extent by the availability of soil water, provided there are
sufficient nutrients and oxygen in the soil. If the soil is waterlogged, there will be little dissolved
oxygen available and the amount of air space within the soil will be reduced. With most crops, the
roots will die if they are submerged for a period of 3 days. High water table and inadequate drainage
will result in a shallow root-zone depth. The soil water supply is alternatively depleted through ET
and replenished by rain/irrigation water. Understanding of the factors that determine the availability
of soil water is, therefore fundamental to efficient irrigation practices.
Permeability
Permeability of a soil refers to the ease with which water moves through the soil and defined as the
velocity of flow caused by a unit gradient. The term permeability is normally used to designate the
flow through soils in any direction.
Soil infiltration, I
Soil infiltration refers to the downward flow of water through the soil surface. It is one of the
important soil properties having greater importance to irrigation. The infiltration rate depends on
physical properties of the soil, such as texture, structure, porosity, moisture content of the soil, degree
of compaction, organic matter etc. Knowledge of the soil infiltration rate is a prerequisite for efficient
soil and water management. Typical infiltration rate for different soil texture is given in Table 4.10.
282
Table 4.10. Infiltration rates related to soil texture
Soil texture
Sandy
Sandy loam
Loam
Clay loam
Silty clay
Clay
Representative I
(mm hr-1)
50
20
10
8
2
0.5
Normal range of I
(mm hr-1)
20 – 250
10 – 80
10 – 20
2 – 15
0.3 – 5
0.1 – 8
Category
Rapid
Moderate rapid
Moderate
Moderately slow
Slow
Very slow
Source: Israelsen and Hansen (1962)
Soil moisture constants
The field capacity and permanent wilting point represent the upper and lower limits of water storage
in the soil and are called the soil moisture constants. Some of the soil moisture characteristics are
shown in figure 5.
Saturation
It is a condition in which all the pore spaces in a soil are filled completely with water. A soil is
saturated or nearly so for a short time after water is applied until drainage takes place.
Field Capacity, FC
Water held in excess will be drained away by gravity. When the rate of downward movement of
water by gravity ceases, a soil is said to reach FC. This will take place 2 to 3 days after heavy rain or
irrigation. The FC is, therefore, the approximate starting point from which plants began to use water
from the soil. At FC the macro pores are filled with air and the micro pores are filled with water
Permanent Wilting Point, PWP
The moisture content of the soil below which the plants cannot readily obtain water and plant remain
wilt (die). Some plants will not wilt but show other signs such as decreased plant height and change
of color. Temporary wilting could occur on a hot, windy day, particularly in the case of broad-leafed
plants, even when the soil is well supplied with water, plants usually recover from wilting when
atmospheric conditions change. For all practical purpose, the value of FC and PWP is fixed.
283
Fig. 5.6. Some of soil moisture characteristics
Soil water content
The water content of a soil can be expressed as follows:
Gravimetric water content ( % ) = weight of wet soil (gm) – weight of dry soil (gm) X 100
Weight of dry soil (gm)
Volumetric water content ( % ) = Gravimetric water content ( % ) X BD (gm cm3)
Water content expressed in terms of depth of water, d
d (mm m-1) = Volumetric water content ( % ) X D (mm)
Water content at FC/PWP (mm Di-1) = (wt. of wet soil – wt. of dry soil) X BD*Di
Weight of dry soil
Where, wt. weight in g BD in gm cm3 and Di in mm
Total Available Soil Water content (TASW)
It is the difference between FC and PWP. Soils differ in their capacity to store water. Coarse like
sandy soils have less available water than well-structured clay soils, because most of the pores in
sandy soils are too large to retain water. Organic matter increases the available soil water capacity.
Table 4.11 shows the range of FC, PWP and available water content for different soils.
284
Table 4.11. Range of FC, PWP and ASWC for different soils
Soil texture
Sandy
Sandy loam
Loam
Clay loam
Silty clay
Clay
(%)
6 – 12
10 - 18
18 – 16
23 – 31
27 – 35
31 – 39
FC
(mm m-1)
100 – 200
140 – 270
250 – 360
300 – 430
340 – 460
370 – 500
(%)
2–6
4–8
8 – 12
11 – 15
13 – 17
15 – 19
PWP
(mm m-1)
30 – 100
60 – 120
110 – 170
140 – 210
160 – 230
180 – 250
TASW
(%)
(mm m-1)
4–6
70 – 100
6 – 10
90 – 150
10 – 14 140 – 190
12 – 16 170 – 220
14 – 18 180 – 230
16 – 20 190 – 260
Readily Available Soil Moisture / Allowable Soil Moisture Depletion, ASMD
It is the portion of the total available water (FC – PWP), which is most easily extracted by the plant
roots without creating stress. The water content approaching PWP cannot be easily extracted by the
plant roots. Therefore, only part of the TASW is used before the next irrigation. The term
Maximum/management Allowable Deficiency, MAD, can be used to compute the amount of water
that can be used without adversely affecting the plants and can be expressed as a fraction of the
TASW. This value varies with crop type and obtained experimentally. Once the MAD is known, it is
possible to compute the net irrigation water requirement, IRn, necessary to restore the main rootzone, Rz, to FC. Values of MAD together with the maximum rooting depth for varies crops is given
in Table 9.
MAD (Fraction) = ASMD/RASM (mm)
TASW (mm)
Irrigation Scheduling
Irrigation scheduling is the process of determining frequency and amount of irrigation water to apply.
In theory, water could be given daily. However, as this would be very time and labor consuming, it is
preferable to have a longer irrigation interval. The irrigation water will be stored in the root zone and
gradually be used by the plants. The irrigation interval has to be chosen in such a way that the crop
will not suffer from water shortage. Different approaches can be used for scheduling irrigation water
application. In these manual, irrigation scheduling is based on MAD. The depth of irrigation water
which can be given during one irrigation application is however limited. The maximum depth that can
be given has to be determined and influenced by the soil type and the root zone depth. The soil type
influences the maximum amount of water, which can be stored in the soil per meter depth of the soil.
Sand can store only a little water or, in other words, sand has low available water content. On sandy
soils, it will thus be necessary to irrigate frequently with a small amount of water. Clay has high
available water content. Thus on clayey soils, larger amounts can be given, less frequently. The root
depth of a crop also influences the maximum amount of water, which can be stored in the root zone.
If the root system of a crop is shallow, little water can be stored in the root zone and frequent - but
small - irrigation applications are needed. With deep rooting crops more water can be taken up and
more water can be applied, less frequently. Young plants have shallow roots compared to fully-grown
plants. Thus, just after planting or sowing, the crop needs smaller and more frequent water
applications than when it is fully developed.
285
Table 4.12. Rooting depth of fully grown crops and MAD
Crop
Alfalfa
Banana
Barley
Beans
Cabbage
Carrots
Citrus
Cotton
Grasses
Groundnut
Lettuce
Maize
Onion
Peppers
Potatoes
Safflower
Sorghum
Soybean
|Sugarcane
Sunflower
Sweet potatoes
Tomatoes
Wheat
Rz (cm)
100 – 200
50 – 90
100 – 150
50 – 70
40 – 50
50 – 100
120 – 150
100 – 170
50 – 150
50 – 100
30 – 50
100 – 170
30 – 50
50 – 100
40 – 60
100 – 200
100 – 200
60 – 130
120 – 200
80 – 150
100 – 150
70 – 150
100 – 150
MAD (fraction)
0.55
0.35
0.55
0.45
0.45
0.35
0.5
0.65
0.50
0.40
0.3
0.60
0.25
0.25
0.25
0.60
0.55
0.50
0.65
0.45
0.65
0.40
0.55
Root zone water content near FC at planting insures rapid early growth and normal root development.
Therefore, pre-irrigation is often desirable particularly in arid and semi-arid climatic conditions.
Moreover, moisture stress from flower initiation to seed formation should be avoided and should be
given sufficient irrigation to meet the day-to-day ETcrop demand with a frequency that maintains
high soil moisture in the root zone.
Step-wise computation of irrigation scheduling for a particular crop
Step 1. Compute ETo and obtain appropriate Kc-values to get daily ETcrop demand
Step 2. Find out the root zone depth at different growth stages
Step 3. Find out the TASW in the root zone for the respective growth stages
Step 4. Find out MAD
Step 5. Divide step 4 by daily ETcrop (step 1), this will give irrigation interval in days
Step 6. Multiply step 5 with ETcrop (step 1). This will give net irrigation requirement for the given growth stage
Step 7. Divide step 6 with application efficiency, Ea. This will give gross irrigation requirement, IRg.
Step 8. Find out additional irrigation water requirement for leaching out the soil, if needed from IRn
1 + LR
Once irrigation interval and amount is fixed, it is a matter of computing the discharge and time
required to refill the soil moisture. The time required to refill the soil moisture can be obtained from
the following relationship:
T=d
I
Where T is time required to refill the soil moisture depleted in hrs, d is the depth of irrigation water to
be applied in mm and I is infiltration rate of the soil in mm hr-1.
The discharge rate, Q, for a particular field can be obtained from:
Q (l/s) = A * d
T*3600
286
Where Q is in lt./sec, A is area to be irrigated in m2, d in mm and T in hr
Problematic soils
Soils, which have limitations of land-use value for plant growth, production, and productivity, due to
soil salinity and/or sodicity or soil acidity or due to water logging problem of the Vertisols conditions,
are termed as problematic soils.
Salt affected soils
The most common source of salts in irrigated soils is the irrigation water itself. After irrigation, the
water added to the soil is used by the plant or evaporate directly from the moist soil. The salt,
however, is left behind in the soil. The salt affected soils can be classified under three classes as
Saline, Saline-sodic and sodic based on general EC, SAR, and pH. The salinity and sodicity are
commonly occurring in arid and semi-arid climatic conditions. The USDA classification of saltaffected soils is given in Table 4.13.
Acid soils
The pH tolerance limits of different plants vary greatly, but for most commercial crops a neutral range
is most suitable, with pH values between 6.3 and 7.5. A soil with a pH value less than 7 is termed as
acid soil. The degree of acidity of a soil is shown below:
Extremely acid
Very strongly acid
Strongly acid
Medium acid
Slightly acid
Neutral
< 4.5
4.5 – 5.0
5.1 – 5.5
5.6 – 6.0
6.1 – 6.5
6.6 – 7.3
Table 4.13. USDA classification of salt affected soils
ECe
(dS m-1)
> 4
ESP
pH
< 15
<
Saline-sodic
soils
> 4
> 15
Usually
8.5
Usually
8.5
Sodic soils
<4
> 15
Usually
8.5
>
Soils
Saline soils
Description
<
Non-sodic soils containing sufficient soluble salts to interfere
with plant growth of most crops
Soils with sufficient exchangeable sodium to interfere with
growth of most plants, and containing appreciable quantities of
soluble salts
Soils with sufficient exchangeable sodium to interfere with
growth of most plants, but without appreciable quantities of
soluble salts
The soil acidity is a common occurrence in all regions where precipitation is high enough to leach out
appreciable amounts of exchangeable bases (exchangeable cations other than hydrogen and
aluminum) from the surface layer of the soils. The acid nature of agricultural soils limits the
productivity and range of crops that can be grown because of low fertility and sensitivity of the plants
to aluminum (Al), manganese (Mn) or iron (Fe) levels found in soils below pH 5.5.
Vertisols
Clay soils, particularly the clay minerals dominated by montmorillonate, are recognized by their
property to shrink when dry and to swell when moist. Following heavy rainfall or irrigation, the
cracks disappear and the soil becomes very plastic, dense, and sticky. This soil is capable of absorbing
considerable amounts of water on wetting and retaining much of it on desiccation, or against suction
and tension forces. The long rainy season or continuous over-irrigation favors saturation and crop
production is constrained because of water logging condition. If the water logging condition lasts too
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long, the plants cannot withstand and may die with the exception of rice. Farmers cropping under
Vertisols in the highland of Ethiopia usually plant crops tolerant to water logging during the rainy
season or plants less tolerant crops at the end of the rains. Both approach cause the farmers to lose
production; crops that tolerate water logging tend to be low yielding, while planting crops on residual
moisture at the end of the rains shortens the growing seasons and hence reduces yields.
Management of problematic soils
The first step in managing the problematic soils is to identify its cause and investigate the extent of
the problem. Once the extent of problems and its cause are known, the second step is to decide
management strategies to control and reclaim these soils
Management and reclamation of salt-affected soils
Reclaiming saline soils
For saline soils with high salt levels to significantly affect plants and reduce growth, reclamation with
excess water is recommended, provided there is enough good quality water available and adequate
drainage. To maintain unsaturated conditions and ensure salts are being leached through the soil
profile, water should be applied in a series of applications and allowed to drain after each application.
Reclaiming sodic and saline-sodic soils
Reclaiming sodic and saline-sodic soils require a different approach than saline soils and can be
considerably more costly. Prior to leaching, excess sodium needs to be replaced from the exchange
site by another cations, viz., calcium, or magnesium. This is done by adding an amendment to the soil.
The most common and economical amendment used on sodic soils is gypsum, which can be applied
dry or with irrigation water. Other amendments include sulfuric acid, sulfur-containing lime and
others chemicals containing calcium such as calcium chloride, and calcium nitrate. Saline sodic soils
should be amended by first addressing the excess sodium problem and then the excessive salt
problem. If soluble salts are leached prior to the removal of sodium, sodic soil properties, such as
dispersion, can result.
Management for salinity control
For salinity control, practices that require relatively minor changes in management include irrigation
that is more frequent, selection of salt tolerant crops, additional leaching, pre-planting irrigation, and
seed placement. Alternatively, that require significant changes in management are changing the
irrigation method, altering the water supply, land grading and modifying the soil profile.
Management of acid soils
The unfavorable soil pH condition can be improved by liming the soil. The lime requirement is
affected by the soils ‘buffering capacity’, which is its ability to resist radical changes in pH. Particular
soil components have a major impact on the degree of buffering capacity. High clay or organic matter
contents increase the soil buffering capacity. Therefore, the lime requirement is based on soil test
procedures to estimate the required lime rates needed to adjust soil pH. The most common target pH
levels are 5.5, 6.0 and 6.5 for mineral soils and 4.5, 5.0 and 5.5 for organic soils.
Management of Vertisols
The adverse effect of water logging in Vertisols can be overcome by draining the excess water using
different technique. The removal of excess water either from the ground surface or from the root zone
is called drainage. Farmers use different techniques for draining Vertisols and the techniques improve
surface drainage or reduce water logging. The technique used include flat bed planting, drainage
furrows, ridges and furrows, handmade broad beds and furrows, post rainy planting and soil burning
(guie). Other improved technique include shaping of land to promote disposal of excess water by
introduction of broad beds and furrows, camber beds, ridges, grassed waterways, etc.
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4.3. Watershed Management
Land degradation, food insecurity and poverty are prevalent problems in Ethiopia. Government and
nongovernmental organizations are attempting to improve the current situation through a host of new
approaches to overcome the problems and bring the desired changes. Watershed management is one
of the approaches that have received much attention in Ethiopia. A watershed approach uses
hydrologically defined areas to coordinate the management of natural resources. The approach is
favored since it considers all activities within a landscape that affect watershed health and livelihoods.
Many countries in Africa, Asia and South America have successfully designed their rural
development programs based on watershed boundaries. In well-managed watersheds of India, return
to investments in watershed development was found to be high, with cost-benefit ratios ranging from
one to greater than two positive changes in biodiversity conservation, land management, income
generation and capacity building as a result of integrated research and development activities in the
Philippines and Burkina Faso. In the two watershed management Vertisol sites of central Ethiopia,
participation of farmers in problem diagnosis, prioritization and implementation was high.
Consequently, Farmer Research Groups (FRGs) were formed to solve their priority constraints. The
collective action in the watershed helped farmers to solve conflicts that usually arise due to excess
water disposal from one farm to the other. Similar advantages for Yeku watershed in the Amhara
National Regional State of Ethiopia.
Evidence suggests that in addition to being a platform for leveraging resources for integrated
conservation and development, the watershed approach improves collaboration and information
sharing among diverse partners. However, experiences on how to diagnose social and biophysical
issues, development and implementation of interventions in an integrated and participatory way in
watersheds are very limited. The topics covered in this handout or manual is expected to serve as a
reference for intended watershed development practitioners.
Concepts
Watershed is defined as an area of land from which water drains into a river, lake or stream. In simple
terms watershed is a topographically delineated area draining into a single channel. Watershed can be
classified into different categories based on their size, drainage, shape and mode of land-use.
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Mini watershed with an area of less than 100 hectares;
Micro watersheds with an area between 100 and 1000 hectares;
Milli watersheds with an area of 1000 to 10000 hectares,
Sub watersheds with an area between 10000 to 50000 hectares; and
Macro watershed with area above 50000 hectares.
From a hydrological perspective, a watershed is a useful unit of operation and analysis because it
facilitates a system approach to land and water use in interconnected upstream and downstream areas.
Integrated nature of watersheds provides a strong rationale for using them as the basis for managing,
restoring, and rehabilitating ecological systems.
Watershed management can be different things to different people:
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A means to increase water quality and quantity for downstream users;
A way to coordinate cross-boundary cooperation of diverse water user groups;
A way to think about NRM issues that cannot be addressed by working with single farm or plot;
A way to coordinate co-management of common property or public lands; and
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•
A way to look at the interface between diverse social and biophysical processes (i.e. water, soil, livestock,
crops, pests) on the landscape.
In general, watershed management refers to the conservation, regeneration and judicious use of all the
resources – natural (land, water, plants, and animals) and human – within a particular watershed. It
tries to bring about the best possible balance in the environment between natural resources on the one
side, and human and other living things on the other. Watershed management is a part of the broader
concept of natural resource management. Natural resources management is a discipline in the
management of natural resources such as land, water, soil, plants and animals, with a particular focus
on how management affects the quality of life for both present and future generations. Thus watershed
management is one of the chief approaches towards sustainable NRM.
Objectives
Since the objective of watershed management varies according to place, region, country and demands
of the people, it is difficult to identify certain common objectives of watershed management.
However, generally speaking, watershed management projects are expected to:
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Conserve moisture in rain-fed areas for optimal production;
Reduce soil erosion and ensure soil and water conservation;
Control the problems of salinity, drainage and alkalinity;
Prevent floods and siltation in reservoirs;
Collect surplus runoff in farm ponds and its recycling;
Recharge ground water and increase water tables in wells,
Meet drinking water demands from human population and cattle;
Improve on-farm irrigation systems for increased productivity; to balance non agricultural uses on land and
water; and
Generate income and employment in harmony with land and the agro-climatic conditions.
Principles
•
Watershed management is based on certain principles that are impertinent for its sustainability and
ecosystem management. A watershed management program should aim at the total development and
optimal utilization of the available natural and human resources. Some of the watershed management
principles are:
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To avoid over exploitation of land and give emphasis to its natural capability;
To give sufficient cover to soil during rainy season with more vegetation and forestry;
Conservation of rainwater using water harvesting or other methods;
Drawing out excess water with a safe velocity and diverting it to storage ponds and storey it for future use;
Avoiding gully formation and putting checks at suitable intervals to control soil erosion and recharge
ground water,
Increasing cropping intensity through intercropping and sequence cropping;
Safe utilization of marginal lands through alternate land-use system;
Ensuring sustainability of the eco-systems befitting the man-animal-plant-land-water-complex over the
years;
Maximizing the combined income from the inter-related and dynamic crop-livestock-tree-labour-complex
over the years;
Maximum productivity per unit area, per unit time and per unit of water;
Stabilizing total income and cut down risks during aberrant weather and situation; and improving
infrastructural facilities with regard to storage.
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Components
The components of watershed management include community development, soil and land
management, water management, biomass management (crop management, afforestation, fodder
development, livestock management, rural energy management and other farm and non-farm
activities).
Land management involves the sustainable management of land resources with a view to increase
productivity and income without affecting the ecosystem characteristics. Land management may vary
in accordance with its natural properties like terrain, moisture, texture and etc. There are different
types of land management including, structural measures, vegetative measures, production measures
and protection measures.
Water management involves the storage of rainwater, surface water and groundwater and using the
same for the benefit of land, people and cattle. Under water management, different methods are used
for conservation and usage of water including rain water harvesting, ground water recycling,
prevention of water balance, checking pollution and above all sustainable use of water without
affecting the environmental balance.
Biomass management involves the areas of intervention like crop preservation, biomass regeneration,
forest management and conservation, plant protection and social forestry, increased productivity of
animal, income and employment generation activities, coordination of health and sanitation programs,
better living standards for people, eco-friendly life style of people, and formation of a learning
community.
Trends
For the last 40 years, concerned governments, development agencies and NGOs have been employing
watershed management principles across the world. However, during the initial years of watershed
management, more emphasis was given to biophysical aspects of watershed management. Social and
economic aspects of watershed management have been given priority only after the 80s. In addition,
people’s participation has been recognized as being one of the keys to successful management of
natural resources. Thus, of late, an integrated concept of watershed management was evolved which
gives focus on community needs and problems as part of the holistic watershed management. The
recent debate on watershed management involves the following issues:
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The role and importance of indigenous technology in soil and water conservation;
The effectiveness of policy and legislation with regard to conservation of natural resources;
The capacity of rural communities and governmental institutions to adequately design and implement
sustainable watershed intervention programs;
The effectiveness of watershed management technologies to produce the desired results, and
The replicability and sustainability of watershed management interventions.
Realizing the potential of watershed based approach in rural development, the government of Ethiopia
also adopted a paradigm shift towards integrated watershed management in the different regions of
the country.
Approaches
Watershed management approaches are basic to identify real biophysical, social, cultural and
institutional issue; potential interventions and project implementations.
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Participatory development approach is one of the watershed management approaches that help to enhance
the involvement of relevant stakeholders in all development process. Participatory management has been
defined as a process whereby those with legitimate interests in a project both influence decisions which
affect them and receive a proportion of any benefits which may accrue. It is now widely accepted that if the
productivity of natural resources is to be enhanced in a sustainable fashion, then those engaged in and
affected by management of the resource—the communities—must participate in plans for its rehabilitation
and management. Their participation will generate a stake in the process and enhance the prospects of both
institutional and ecological sustainability. The efficiency and importance of participatory watershed
management approach has been claimed in the promotion of linkages among farmers and between farmers
and institutions; for the creation of opportunities for farmers to disseminate actively technologies to other
farmers; for engaging farmers in searching for their own solutions to problems; for building up farmers’
capacities for managing their resources; and for changing attitudes of development workers and institutions
towards farmers, as well as towards each other;
Approaching problems and developing interventions from an integrated or system perspective is another
important aspect to properly manage the watershed issues. Confronted with the complexity of the problems
facing farmers, an integrated approach often needs to be taken which works with different components of
the system, including social, economic, biophysical, and policy dimensions;
Creating partnership: A partnership is a strategic alliance or relationship between two or more
people. Successful partnerships are often based on trust, equality, and mutual understanding and
obligations. Partnerships can be formal, where each party's roles and obligations are spelled out in a written
agreement, or informal, where the roles and obligations are assumed or agreed to verbally. Partnerships
between the concerned agencies need to be structured with each playing a role according to its comparative
advantage (Perez and Tschinke, 2003). Governments for example can provide technical assistance and
guidance, economic incentives, an enabling legal framework with clear territorial rights, formal conflict
resolution mechanisms and financial and technical support for decentralized monitoring. Communities
contribute local ecological information, knowledge of economic and social conditions which enables them
to devise well adapted rules and procedures, low cost customary conflict resolution mechanisms and self
monitoring mechanisms; and
Gender sensitivity: the involvement of women in the watershed management processes is key and timely.
We have to ascertain and give requisite weight to women’s perceptions and priorities in the formation of the
watershed action plan. They are the ones who are mostly affected from environmental hazards (Lakew et
al., 2005). For instance, they are walking long distances to fetch water and fuel wood. Capitalize on
indigenous practices and knowledge: best practices and knowledge of the local people can be entry points
for watershed management.
Processes
Awareness creation and team formation
Stakeholders that have says on a particular watershed should be identified and informed about the
watershed development program through a workshop, public meetings and awareness campaign. It is
then teams that composed of interdisciplinary or multidiscipline areas are created. The disciplines or
specialization can be gender specialist, crop, livestock, soil and water, forestry, socioeconomics,
geology, land-use, GIS, agro-meteorology and others. Watershed site teams can be also formed from
representatives of the stakeholders of the specific watershed.
Site selection and delineation
Selection of appropriate site is fundamental for the success of watershed development effort. Some of
the criteria for site selection include:
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Agro-ecological representation;
Resource management and land degradation problems;
Distinct outlet and hydrologic boundary;
Social and administrative boundary of the watershed;
The level of GOs and NGOs interventions;
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Size of the watershed;
Accessibility; and
Participation of stakeholders around the watershed site
The watershed boundary can be delineated using primary data (GPS readings), secondary data
(topographic map 1:50,000 or larger) and in consultation with the local community. The delineated
watershed can be geo-referenced and digitized for its contour, roads, rivers and other features. The
preliminarily delineated boundaries have to be verified in the field using GPS and establish reference
benchmarks for future operations. Finally, map of the watershed can be produced, and other
information such as elevation ranges, area, slope and aspect extracted.
Exploration
Resources/systems characterization
The resource/systems characterization activity can include the following:
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Topographic survey (drainage network, elevation, slope, as well as water sources);
Collection of climatic data from the nearest met station;
Mapping of the land use/land cover of the watershed using GPS readings. The knowledge of the local
communities on the trend of the land use/land cover in the watershed should be also considered;
Characterization of the soils of the watershed (local classification, soil sampling, profile descriptions);
Detailed information on human (households, family size, age, education and wealth status) and livestock
population;
Crop husbandry and cropping systems of the watershed;
Inventory of tree and forest resources and further characterizing based on their potentials;
Characterization of introduced natural resources management technologies and local practices;
Characterization of local institutions, common resources, collective actions, laws, bylaws and their setup
and functions; and
Policies, institutional and economic environment
Identification of watershed issues
The following can be possible guidelines to identify major issues/problems at the farm, landscape and
watershed levels:
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Capture diverse views through semi structured interviews more systematically from different social groups
such as wealth (wealthier and poorer households), gender (male, female), age (elders, youth) and – in
watersheds where the location of landholdings differs greatly by household, and may influence the extent to
which natural resource degradation influences livelihoods – landscape location;
Produce the list of watershed issues from all the groups;
Once watershed issues have been identified by different social groups, responses from the different groups
are consolidated or lumped into a single list and repetitions eliminated to reduce the list to a manageable
number of issues for subsequent ranking and planning;
Two complementary approaches can be used for participatory identification of watershed issues. The first is
participatory mapping. It helps to identify watershed issues with a strong spatial dimension. It also
complements semi-structured interviews. The second diagnostic tool is historical trends analysis. The
strength of this tool is in elucidating key changes in landscapes and livelihoods over time and their causes.
The tool is implemented in two stages:
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an open-ended dialogue on observed changes in landscapes and livelihoods over time;
identifying the causes behind each observed trend; and
quantifying each of the observed changes and associated causal variables through participatory ranking.
Formal surveys can be also conducted when there is a need to quantify some of the findings from the
discussion and interviews.
Ranking of the watershed issues
Once the watershed issues or problems are identified, ranking can be done as follows:
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Consult a representative sample of watershed residents from different groups (gender, wealth, age and –
where relevant – landscape location).
The groups rank the relative importance of identified issues.
Two ranking methods can be tested: absolute and pair-wise ranking.
Pair-wise ranking: Each issue is compared with each other issue, and the number corresponding to the most
important of the two is entered into the box.
Absolute ranking: Participants are asked to give a rating of 1 to 10 for all identified watershed issues
Community feedback and validation
When such formalized processes of soliciting views from diverse social groups is used rather than the
community fora, it is necessary to feed the results back to the community for interpretation and
awareness raising. This step enables the community to ‘own’ the results by moving from a more
extractive mode of data collection (albeit through consultation) to a more interactive approach
grounded in collective dialogue. This is generally done as part of the participatory planning exercise,
ensuring that the priorities of different social groups are clearly brought to the fore in planning.
There is a tendency to validate the results at this time by asking, “Does this adequately reflect your
priorities?” to the group gathered. Yet caution should be used to avoid undermining the systematic
efforts used up to this point to capture a diversity of views. All too often, an outspoken individual who
disagrees with the ranking will try to tamper with the results by saying, “this is not the main priority,
but rather this other one.” This can undermine the attempt to equitably elicit views. We would
encourage, rather, that you simply seek clarification for why the views of the different groups might
differ. This will further collective understanding of such differences rather than marginalize them,
helping to ground the participatory planning process in principles of equity and mutual awareness.
Clustering of identified issues
The rationale behind clustering of watershed issues is that such issues should be managed jointly to
enable greater pay-offs from investments and explicit management of the causal interactions and spinoffs (both positive and negative) characterizing interactions between these issues at present and after
any intervention. Two major steps can be followed to create clusters:
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Sort out watershed issues with high ranks by most social groups: focus on the issues that have relevance to
most watershed residents and receive broad social support within watershed communities;
Differentiate watershed issues with strong functional relationships: identify watershed issues that are
functionally linked and managed jointly;
Two possible strategies for identifying watershed issues with strong functional relationships;
Make a graphical representation of the current causal linkages among the identified watershed issues; and
Look at the short list of issues emanating from the participatory ranking exercise, and try to lump them into
smaller clusters based on their functional relationships.
Identification of entry points
Entry points emanates from the pressing problems of the communities. They are important for farmers
to develop confidence on researchers and improve subsequent communications. Entry points can be
crop varieties, drinking water, soil and water conservation measures, dairy cows, and others.
Identification of opportunities
Opportunities can be rich practices or innovations of individual and group of farmers; social
organizations or local institutions; laws, by-laws, beliefs; and available resources that contribute to the
success of watershed development endeavors.
Action/intervention planning
Watershed management plan vary in scope of efforts, geographical area and objectives.
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Development interventions/ solutions can be defined at the cluster or sub-cluster level;
Ask farmers to propose solutions for prioritized issues or problems;
The development team can bring their own ideas into the discussion only after farmers pose their solutions;
Develop a preliminary list of actions for issues requiring farmer exposure to real-life examples from
elsewhere, issues requiring immediate development actions, and issues that require research attention; and
Integrated development protocols must be developed for each cluster.
Implementation
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Ensure that the community owns the watershed management development plans.
Implementation can begin at min-watershed level or landscape level
Collaborating groups of the watershed management undertake implementation.
Involve as many locally organized groups as possible.
Monitoring and evaluation
Monitoring implies the periodic or continuous collection of data using consistent methods. Monitoring
is used to serve several purposes such as to determine sources of impairment, to provide input for
management tools, and to support scientifically based decisions. The participatory M&E can be done
at the watershed level, with local interest groups, and by the development team itself following the
standard procedures.
Impact assessment
Done regularly with the help of external agencies to assess the impact of the interventions in the
watershed. The assessment is done against the indicators developed at the watershed level.
Scaling out and up lessons
Scaling out (horizontal) is the replication of sites or projects to other locations at the same scale, for
example, from one site to other sites, or from one watershed to another. Scaling up (vertical) refers to
the expansion in the area of coverage, for example from site to micro-watershed, from microwatershed to watershed, from watershed to region, from local to national levels. This section describes
the importance of the participation of local organizations in expanding technological innovations in
the reference-site’s area of influence.
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The success stories and major lessons have to be scaled out and scaled up;
Publicizing the lessons can help as a learning ground for watershed development beginners;
Scaling out and up the watershed management lessons helps to reduce the cost of operation for new
watershed sites; and
Local institutions can have an important role for mass mobilization and technology dissemination. Because
local institutions are based on interests, group members are more or less homogeneous. One farmer is
mostly a member of more than one institute. That means if one farmer is informed about a technology, he
can disseminate to other members faster, so information exchange is so fast.
Lessons from Model Watershed Management Sites
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Forming farmers’ representative team in a watershed facilitates communication and resources inventory
activities;
Identification of the categories of farmers that have different forms of interaction with the watershed
resources is necessary to understand their needs, contributions and decisions;
Reflection/feed backing at different levels of the watershed studies helps to improve approaches for
subsequent actions;
Detail social studies are necessary in the watershed to optimize NRM, production and utilization (e.g.
demonstrate the communities where there are success stories);
Farming communities and local administrators express their commitments very fast when research and
development partners try to work with them on priority issues, for example, commitment and
contribution for improvement of watering points);
Watershed management development agendas can be implemented when they are supported by
interventions that give immediate benefits to the farming communities (e.g. improved crop varieties).
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Linking the high value commodities/produces to the market benefits the communities and encourages
them to participate in various development activities (e.g. Potato seed sources at Galessa watershed and the
surrounding areas, west Shewa zone, Oromia region);
Collective action institutions are good entry points for NRM. Thus, the attention to analyze collective
action institutions must be strengthened and their values and rules must be integrated with the government
policies;
Planning together with the different stakeholders of the watershed on exist strategies are very important to
continue the watershed management initiatives; and
Proper documentation of watershed management approaches/ processes is very important to develop
methodologies that can be referred by other watershed management practitioners, for example, production
of communication products.
Remarks
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Working in watersheds requires consideration of property rights and collective action institutions at the
landscape level. Watersheds invariably include resources that have different types of rights and rules
associated. There are interactions between the resource users, the resources themselves, and the institutions
that govern their access, use and management. The goal of watershed development and research is thus to
understand these interactions at different scales and to use that knowledge as a basis for designing policies,
institutions and technologies that result in sustainable management. Quantitative information and principles
about these interactions can help to prioritize problems and interventions;
Stakeholder involvement in design and implementation can improve the effectiveness of watershed
management projects. However, conventional methods of identifying stakeholders and facilitating their
interaction are challenged by the diversity of stakeholders, interests, and claims on watershed resources.
Accurate information on the impacts of human activity on watershed processes is the currency of
participatory watershed management;
Understanding the nature and distribution of impacts across the range of different stakeholders is especially
important in participatory watershed management since these impacts affect on people’s willingness to
participate and engage in collective action for watershed management; and
Reaching and generalizing from conclusions from specific watershed interventions will require careful
evaluation of results derived from a range of methods and sources. Building monitoring and impact
assessment into a watershed project from the beginning makes assessing impact much easier.
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5. DAIRY MANAGEMENT
Definitions of Livestock Management Provision of suitable environments (feed, shelter and health care) ) to live and to produce for the given animal at
different physiological stages for optimum level of production and profitability could be referred as
management In general terms livestock management could also be considered as establishing favorable
environment for an animal to produce, reproduce and live under normal conditions. Therefore, aappropriate
livestock management implies matching the animal genotype; physiological status production level, age weight
and growth to the available resources so that the resource can support the animal to express their optimum
productive and reproductive potentials. Hence, basic knowledge and experience of the livestock owner (manger)
are very important to achieve the intended level of production and productivity.
Factors of maximum production in livestock
Factors of production in Dairy = (Genetic potential of the animal X Production environment X Management
skill)
Production environments
• Feeds and feedings
• Shelter / shading
• Ecology
• Health management etc…
Hence, livestock management comprises genetic potential of the animal, production environment and
management skill of the owner (manger) to succeed in production, reproduction and profitability.
A proven high grade dairy cow may not express her full potential for production unless supported by full
packages of management that could apply to the intended level of production expected from the animal That is
why being a crossbred cow dose not mean a high producing cow, unless proper application of management is
put in place with the full know how of management skill
Effects of Management on Livestock Production
As has been indicated above animals can not express their full genetic potential under poor level of management
Poor management could be explained by:
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Stunted growth: calves growth is poor and stunted
Low productivity (low milk production, poor meat quantity and quality, less quantity of egg, low
power output etc.)
Poor reproductive performances :Prolonged age at first puberty and their by prolonged age first
calving
More service per consumption
Long calving interval
High Infertility etc.
Basic Requirements for Inception Dairy Production
1) Site Selection for Shelter / shade
Proper site selection is per requisite for dairy enterprise inception. Site to be selected comprises all barn
construction, feed storage, hay shade, handling facilities including treatment facilities, installation of weighing
bridge etc.
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All facilities to be placed should be well planned and designed carefully. Any deviation from poor planning of
basic facilities could account against profitability of the enterprise as it affects productivity of the animals. One
has to get adequate information and knowledge of dairy production and management during the initial planning.
Otherwise he has to look for professional assistants.
In site selection for barn construction gentle slop, well drained and easy to clean system of design has to be
thought of. Therefore:
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Select gentle slop oriented land between the top hill and bottom land as shown in the diagram.
Arrange the barn East west direction as much as possible to avoid excessive sun heat.
The hill side cold protect the animals from excessive wind
The gentle slop has to be arranged in such a way that waste products can be properly flow down to the
fields or to slurry system based on the farm size and management system implied.
adequate water supply system has to be implemented to facilitate all barn operation and cleaning
including drinking for the animals
One has to think of further extension of barn based on number of animals to be reared in the barn
To ensure flow of fresh air in the barn the height of the barn from the ground has to be as high as at
least 4 meters
The floor of the barn has to be rugged, non sleepy to avoider sudden fall down and brakeage of
pregnant animals
In general barn construction has to be based on locally available materials to reduce the overhead coast,
without affecting or compromising the basic requirements of the animals
Table 1 required size for major category of animals are presented as follows
Animal type
Required Pen Size
Total area
A Crossbred Cow
1.75 x 1.5 m
2.6 m2
A Crossbred Heifer
1.5 x 1m
1.5m2
A Crossbred Bull
2 x 1.5 m
3m2
Source HARC
2) Feed Trough
A feed trough has to be well designed to accommodate different category of animals (Cows, Calves, Heifers,
Bull Calves, Breeding bulls etc.) Basic requirements for planning feed trough are its accessibility by different
category of animals, capacity to accommodated required size of animals.
3) Calf Feeding Trough
Size of calf feeding can be designed as (37x 65x90 cms). The front side of the trough must be V-shaped to
ensure access to concentrate and roughage feeding, while the other partition is left for placing pails for drinking
water or whole milk depending on the type rearing and age of calf to be reared.
4) Heifer Feeding Trough
Heifers are reared as a replacement cow for the future. Hence, special care has to be taken in feeding them.
Heifers must have their own feeding trough designed as 72x70x1.25 = 0.63m2. To facilitate easy access to
feeding materials the trough must have V-shaped orientation in the front. Partition between two heifers has to
be in place to separate one heifer from the other.
5) Cow Feeding Trough
298
Feeding trough of milking cows could be designed based on the number of animals to be milked and
arrangement of the feeding plan. This could be arranged head to head (preferred), tail to tail, tandem parlor in
case of milking machine which has got different types and sizes ( ten cow, 12 cow unit, etc). The size of trough
for milking cows is bigger than that of non milking cows. This is not less than 86x76x130 cm. The height from
the ground could be as high as 50cm and V-shaped from the feeding site. There has to be partition between the
feeding trough and laying place. As has been indicated in the general requirements for designing dairy
construction, specially that of dairy cows has to be well drained and easily cleaned place.
6) Pregnant Cows Feeding Trough
Special attention is required for pregnant cows starting from 7 months of pregnancy onward. This is because
over 85% of the fetal growth and development occurs during this stage. Therefore, pregnant cows need special
barn designed to meet this requirement. Unlike barn for milking cows, the size of barn for pregnant dairy cows
is larger. The size could be 86 x76x140 cm. heights from the ground and partition to separate one cow from
other is similar with other cows.
7) Maternity Stall
Maternity stall is place where pregnant cows are kept until calving. This place has to be safe and convenient for
the pregnant cows. During this time pregnant animals are separated from the herd and are supplemented with
steaming up ration which is very important for the cow as well as for the fetal development. 4-6 kg of
concentrate, adequate hay, clean water and exercise is required during this period. Thus the floor size of
maternity stall for one cow has to be 4x3 by 1.30 m high above which about 50 cm open entrance gate of 1.20 m
is advisable to facilitate free movement. The feeding trough can be similar with that of pregnant cows. Care
should be taken when making the floor to avoid slippage. Feed trough in the maternity stall must have free
access of feeding possibilities, and watering
8) Bull Pen
Dairy bull is required to be closer to the main herd for proper management and handling of service. Bull pen can
be constructed in connection with exercise pen to economically utilize space and ensure proper facilitation of
bull service and safety of the workers. Individual bull pen size can be set as 70x65x140m with adequate supply
of watering and feeding trough in the same pen.
Table 2 Summary of Barn Size for Different Category of Dairy Animals
Animal type
Required barn size
Calf
37x 65x90 cms
Heifer
72x70x1.25
Cows
86x76x130 cm
Pregnant cows
86 x76x140
Maternity Stall
be 4x3 by 1.30
Bull pen
70x65x140m
299
Management of New Born Calf
New born calf must be cleaned with clean material and be assisted to birth by holding the back leg up and the
head down for one minute. The calf must be left to the cow to leak and clean. In few minutes time the calf must
be fed with colostrum. Colostrum is highly digestible feed source, which have 40% higher nutritive value over
the ordinary milk. It is laxative and assists for expulsion of wastes from internal organ of fetal. It is rich in
carotene, vitamin A and E, also contains anti bodies, which protects the calf from different diseases and
infections by nature.
1)
Feeding Calf to Weaning
Table 3 Whole Milk Feeding for Calves
Days on col/WM
Am
Pm
T/D
Total
4 days (colostrums )
1.5
1.5
3
12
11 days (whole milk )
1.5
1.5
4
33
27 days (whole milk)
2
2
4
108
21 days (whole milk)
1.5
1.5
3
63
21 days (whole milk)
1
1
2
42
14 days (whole milk)
0.5
0.5
1
14
(98 days) total
260
300
Gradual increase of solid feed and decrease whole milk feeding is the right strategy to feed calves from birth to
weaning.
1) Suckling Methods
Commonly there are three method of suckling calves, depending on the type of rearing methods identified by
the owner. These are:
• Bucket Feeding
• Suckling
• Partial suckling- recommended for smallholder production
All types of suckling methods have advantages and disadvantages. Bucket feeding is economical in using the
milk for the calf and for market, because the milk is weighed and given to the calf based on the weight of the
calf. However, it needs intensive care of cleaning utensils and also demands more labor to facilitate the feeding
operation.
Direct suckling of calves is advantageous for calves. However, since milk is an expensive food for all groups of
ages in human being it has to be saved for food. Therefore, it has to be a compromise between the demand for
food and also the need for calf growth. Some producers give priority to calf feed, especially if the calf is heifer
to be grown for replacement.
Partial suckling balances the supply of milk for the calf and the farmer. In partial suckling method calves are left
to suckle all four teats of their dam for about two minutes. After two minutes calves are kept in front of the dam
until the milkier totally milks all the milk from the dam. Finally the calf will be allowed to suckle the rest of the
milk for almost 15 minutes. This time the calf stimulates the dam to let down adequate amount of milk for the
calf.
Fig 3 Partial suckling: Recommended suckling type for stallholder Dairy production
301
2) Determination of weaning Age
Calves can be weaned at different ages. Weaning age is determined by type of management, production
objectives and availability of feed. Generally age at weaning calves is between 63 – 70 days under application of
improved management and availability of milk replaces. General recommendation for calf waning is 90 days.
Extending weaning age over 90 days is not recommended, since dose not brings any additional advantage.
VI
Rearing Heifers
Heifers are in the age category of 12 to 18 menthes. These are replaces of cows. That is why they have to be
well managed. Heifers should attain proper body weight at proper age. They need to have proper breeding body
condition, ie not too excessively fat or excessively thin (under fattened). Heifers must have pedigree recorded
information, and health recorded. Heifers in a good body condition and health status have to be watched for heat
(desire for bull service) at 200 kg body weight. Ideally heifers has to be served at an average of 230 kg body
weight in normal condition Therefore, heifer management includes every aspect of production reproduction and
growth in a holistic manner.
1. Constraints in Heifer Rearing
Major problems in heifer rearing in Ethiopia are delayed age at first heat and service. Age at first heat in local
heifers is 56 months ( approximately 5 years) while crossbred heifers reach age first heat between 30 to 40
months. This is attributed to the change in body weight of calves after weaning. Pre weaning growth rate of
calves is 450 gm / day and this drops up to almost 200 gm/day.
2. Management Options to Accelerate Post Weaning Growth
To balance the wider range of weight change between the pre and post weaning, feeding based management
options has to be applied to bring about accelerated and balanced growth rate. Under this management it is
possible to enable heifers to come in heat, served and conceive at reasonably earlier age.
Table 4 Reproductive performances of heifers under different feeding regimes
Post weaning Feeding Treatments
Parameters
50:50 C:R
30:70 C:R
G+2h+1con
G+2h
Age at first heat (days)
441
536
588
789
Weight at first heat (kg)
221
247
247
239
Service per conception
2.5
2.4
2.6
2.3
Age at first calving (days)
788
864
962
1150
Gestation length (days)
273
267
280
277
50:50 C: R = concentrate to roughage ratio
30:70 C: R = concentrate to roughage ratio
G+2h+1con = grazing +concentrate g + hay
G+2h = Grazing + hay
Feeding nutritionally quality feed (appropriate energy and protein balance) in the post weaning periods for crossbred
heifers coupled with indoor management promotes growth, reproduction and production performances. In the
contrary, as level of concentrate feed supplementation decreased and the type of management is changed from
indoor to out door, prolonged age and weight at puberty could take place. Research findings have proofed that
nutritional manipulation and management programs in the post weaning period for crossbred dairy heifers could
accelerate growth and support the daily growth rate of ≥ 500 gm.
302
This could be realized under intensive management system by ensuring the level of concentrate feed in the daily
ration up to 50% concentrate and 50% roughage (native grass hay) at the rate of 3% of their body weight, as feed is
secured until the first heat. Under this management level age at first heat could be between 405 and 477 days,
enabling the heifers to calve at approximately two years of age. If calving at two years of age is successful, it could
influence the economic returns and also provide favorable environment for genetic improvement of the herd, since it
also speeds up selection procedures in the herd. Therefore, the relatively higher cost of feeding can be compensated
by the return gained from production of calve and milk at earlier age and subsequent contribution for genetic
improvement.
Under similar intensive management if post-weaning management feeding level is lowered as 30:70% ratio of
concentrate to roughage at the rate of 3% of their body weight the daily growth rate of 430 gm could be maintained.
At this rate of growth crossbred heifers could reach age at first heat at about three months later between 502 and 572
days. Statistically this difference is significant. But in real term it is still the best option for relatively resource limited
producers, who could not afford to buy adequate concentrate feeds. Accordingly, small scale dairy producers can
take up this option as a rearing practice for cross bred dairy heifers.
The grazing based and out door management system delays age at puberty in crossbred heifers. As it is reflected in
the result of experiment two in this study, the grazing and supplementation of one kg of concentrate and grazing with
no concentrate supplementation delayed age at first heat up to five months and 12 months respectively than the ones
supplemented indoor. Supplementing crossbred heifers with at least 1kg of concentrate feed and 2 kg of additional
native grass hay after 8 hours grazing may advance age at puberty by 9 months than the non supplemented crossbred
heifers. This option could be taken up by resource poor farmers in villages.
Attempts to rear crossbred heifers below the management options listed above are not advisable. To start
efficient heifer rearing enterprise one has to strictly follow recommendation rate of feeding and type rearing
practice.
I. Management of Dairy Cows
Among other issues to be considered in dairy cows management, heat (desire for service) detection is the
priority task that needs more attention. For a cow to produce milk, she has to be pregnant and calf successfully.
Therefore, basic knowledge of heat detection and experience is very important
Basics of Heat Detection
Standing heat (estrus) is the time when the cow stands to be mounted by other cows or a bull. The heat (estrous)
cycle (number of days from one standing heat to the next) of the cow averages 21 days. Heat cycle length is
usually consistent for an individual animal, but can vary from 18 to 24 days. The average cow will be in
standing heat for 8-12 hours. Some animals may stand for only 4 hours; others as long as 24 hours. Actually
seeing the cow stand when mounted must be the main goal of owner.
A successful heat detection program in a free stall or loose housing situation requires watching cows at least
two, preferably three times each day, and devoting up to one-half hour per group per watch
One-hour observations at 7 a.m, 12 noon and 4 p.m. resulted in detection of 91% of the cycling cows. The best
time for the first watch is before morning milking, because a high percentage of cows exhibit heat in the
morning. Cows should be observed again during the day and the last watch should be conducted in the evening.
Table 5 Distribution of Mountings by time of the day
Time of Day
Time Percentage
•
12 midnight - 6 a.m
43
•
6 a.m. - 12 noon
22
•
12 noon - 6 p.m
10
•
6 p.m. - 12 midnight
25
303
The three major observations for standing heat must be done at times other than milking, feeding and manure
scraping. Of course good managers are always observant and will catch cows in heat at times other than the
designated observation periods. Heat detection must receive high priority. If possible make heat detection the
job of one particular family member or employee who believes heat detection is important.
Dairy farmers must be aware of the secondary signs of standing heat, but should use that information wisely.
The goal must still be to actually see as many cows as possible in standing heat. A cow that is mounted once or
stands when mounted in a crowded holding pen because she couldn’t more may not be in standing heat. Be
honest with yourself. If you are breeding several cows which have not been seen in standing heat, you have to
check your follow ups seriously, because your detection is not going well.
Be aware of the external signs of heat as listed below:
•
•
The cow in heat stands when mounted by other cows.
The cow in heat is more active than when she is not in heat and may mount other cows or try to get
them to mount her, particularly when coming into or going out of heat.
• The cow in heat may raise tail, roam and/or bawl, and hair may be roughened on the rump.
• Mucus may be seen on the vulva and tail.
• The vulva is swollen, large, and moist and smooth compared to when she is not in heat.
• Her milk production and feed consumption may go down, and her behavior might change.
• Blood may be discharged from the vulva 12 to 48 hours after the cow has gone out of heat. When
you see a bloody discharge, it only means that the cow was in heat, not that she is pregnant or
open. Start watching for the next heat 18 days after blood is observed.
Shay breeders
These are type of animals that dose not show full sign of heat, but still in heat. These animals deprive from
feed, kick away their calves. There are series of mechanisms to detect such heat
I.
•
•
•
Simple palpation: the temperature of the cows vulva may raise
Close follow up of deviations
Use of teaser bull
3) Service:
•
•
•
After calving, cows my show heat signs 3 – 4 months some times even earlier. However, they
should not be served until 60 days after calving. This is to maintain the normal uterine function of
the cow to be in normal function position.
There is a need to properly supply the cow with palatable supplementary feed to stimulate heat and
normal body functions
Serous follow up of heat detection is important
304
Use of teaser Bull
1. Feeding Management of Dairy Cow
In dairy production, feeding management has a considerable influence on success and profitability of the
enterprise. Appropriate feeding involves providing each animal with a ration that meets the requirements for
maintenance, production and reproduction. Feed requirement for milk production and maintenance in milking
cows often exceed the nutrient supplied by feed intake at various stages. Supplementary feeding increases milk
production and their by increases negative energy balance and improves the early reproductive traits after
calving. Adequate level of production cannot be achieved on solely roughage-based diet. Concentrate is fed to
dairy cows to provide the nutrients required for the cow to produce more milk close to her genetic potential for
milk production.
Energy and protein feed intakes are regarded as the main factor affecting production and reproduction of cows.
The main local sources of energy in the dairy ration are cereal-based feeds while those of proteins are mainly
oilseed cakes. These are primarily obtained from cereal by products such as wheat bran, wheat middling and
others. Oilseed cakes (noug cake, cottonseed cake etc.) are industrial by-products, which are characterized by
low fiber and comparatively higher nitrogen content. Inclusion of these by-products in different proportions in
the ration of milking cows as sources of protein is a common practice in small-scale dairy production system.
Concentrate feeding is a common practice across all urban and peri-urban dairy production systems in the
country.
Table 6 commonly used concentrate feed for dairy cows and their mixture
Ingredients
Different Rations and their constituents
Ration 1
Ration 2:
Ration 3:
Cottonseed cake
40%),
0
35%),
Noug cake
0
30%
0
305
Wheat bran
58
67
30%
Wheat middling
0
0
31%
Salt
1%
1%
1%
Mineral
1%
2%
3%
Total
100
100
100
The basal diet which is commonly native grass hay (93% DM) could be provided ad libitum. Supplemental
rations based on the daily milk yield is supplemented with at the rate of 0.5 kg per one kg of daily milk yield
from any of the concentrate mixture listed above as available.
Feeding management of dairy cows can be further divided in to two parts. These are:
1.Pre partum feeding management. The pre partum feeding management are sub divided into three main
marts depending on feed requirements and physiological states of the cows
• Service to 3 months. Animals can be fed on maintenance ration alone. This can be obtained from good
grazing land, available green grass or properly conserved good quality hay. In case of deviation from
unavailability of such feeding situation, animals can be supplemented with quite lower level (up to
0.5kg) of daily concentrate feed.
• Three to 7 months of pregnancy: Animals must be fed additional supplemental ration in addition to the
maintenance ration. The basal diet can be ensured from good grazing land, available green grass or
properly conserved good quality hay. However, since the fetal development is about to start and the cow
can also be in milk, she needs additional fed supplement. Base on the body condition, amount of milk,
animals can be supplemented with 0.5 kg concentrate / kg of milk yield or up to 2 kg /head if not in
milk.
• Steaming up Ration: Steaming up ration is a ration fed to pregnant animals from seven months to
caviling. These are important ration both for the cow and the new born calf. Eighty to 85 % of fetal
growth occurs during this period. Pregnant cows should be separated from the herd and be fed indoor.
Adequate basal diet prepared from good quality hay is preferred. In most cases where the measuring
facilities are available, six to eight kg s of hay supplemented with four to six kg of concentrate feed. In
all level and type of feeding management, pregnant animals have to have adequate clean water and safe
exercise. If the pregnant animal is heifer, it is advisable to massage the udder gently for 20 minutes
using warm water and frequent patting for taming
2.
Post partum feeding management: Post partum feeding management covers periods
•
3.
Early lactation (calving to 3 months): Rapid loses of weight can occur at this stage due to
lose of appetite as a result of labor and calving difficulties and inconveniences. Drop in
mineral (magnesium) can occur at this stage, which can result in paralysis. Care should be
taken to maintain body weight, by feeding palatable green greases and easily digestible
concentrate feeds.
• Mid lactation (3-6 months): Animals are fed according to their milk yield. I.e., 0.25 – 0.5
kg of concentrate and 6 -8 kg of hay per day is generally recommended. Follow up of heat
detection is important
• Late lactation (6- weaning): late lactation is the period towards the drying period for the
cow. Accordingly, feeding management has to target to maintain body condition and the
low milk yield obtained during this period.
Care during calving:
• Clean safe and bedded maternity stall should be prepared prior to calving
• Follow abnormal parturitions: normal parturition is when the head of the calf lies on the two
forelegs and come at that position. Any deviation from that position is considered as
abnormal, and should be corrected by veterinarians or experienced herd man
306
Normal parturition
•
•
•
•
•
Supply adequate clean drinking water
Leave the animal to lay down freely
Take care of retained placenta. Placenta should be expelled in few minute by itself normally.
Any further delay should be reported to veterinarian.
Supply easily palatable feed
Report any deviations from healthy condition
II. Dairy Bull Management
Commonly it is said that “bull is half a herd”. This is to mean that, a single bull in the herd is a father of many
calves. Therefore management of bull has to take due attention more seriously.
The management of bull has to focus on:
•
•
•
Taking care not to be over fattened
Taking care not to be under fattened
Keep the bull at normal body condition
307
This could be achieved by feeding enough green grass or good grass hay adlib. Concentrate supplementation can be
offered based on the body condition and service intensity of the bull. Concentrate supplement for dairy bulls can be
prepared more form protein source in which reasonable quantity of energy sources is included. Salt and mineral
sources are added in fairly low quantity. Unlike that of dairy Concentrate, concentrate for bull can have more protein
source in them. Rations in table 6 can be modified to be used for dairy bull.
Table 7 Dairy Products Market Channels
Dairy Products
Fresh milk
Butter
Local Cheese
Market Channels
•
•
•
•
•
•
•
•
•
•
•
•
Producer to Consumer
Producer to Trader (Hotels, and Cafes) to Consumers
Producer to Cooperatives to Consumer
Producer to cafe (processed to Ergo) to consumer
Producer to Consumer
Producer to Cooperatives to Consumer
Producer to Retailers to Consumer
Producer to Retailers to Wholesalers to Consumer
Producer to Retailers to Wholesalers to Retailers to Consumer
Producer to Consumer
Producer to retailer to Consumer
Producer to hotels consumers
II. Production of Clean Milk
Milk is a quality food for all ages of human being. The unique characteristic of milk as a food is the presence of
highly important food item that one may not find in any other plant product. As it is also very important food
item, it is also highly perishable product. Since milk is a suitable media for all micro organisms, it could be very
easily be spoiled by contamination. Contaminated milk is dangerous for human health. Therefore milk
production must be targeted both on quantity and quality of products, rather than only maximizing milk
production alone
Producing milk both in quality and quantity will have more market value, quality product for consumption
healthy food. This insures more public health, and saves additional expenditure to be spent on health care, and
protects transmittable disease through milk.
Clean milk production starts from preparation of milking parlor, milking utensils, and hygienic conditions of the
millers. Therefore, all pre conditions that are required for milking operation have to be in place before the
milking starts.
•
The cow has to be clean before milking: this is done by frequently cleaning the dairy barn, and if
there are remaining feces and urine on the body of the cow, it has it be cleaned thoroughly.
• Clean the udder and teats by massaging with clean cloth / peace of towel carefully.
• The milkier is required to thoroughly clean his hand with soap. He has to put on clean white apron, and
cape to protect his hair. Itching any part of his body or cleaning his nose until milking ends is forbidden
Always he has to be advised to cut his finger nails, to avoid any scratch on the teat of the cow
•
If the milking is by machine, the machine has to properly clean as per the manual indicated by the
manufacturer.
• Milk is perishable and has the capacity to attract any smell from surroundings and or contaminated
quickly. Hence, it has to be immediately boiled and cooled in safe place after being milked
• Milk utensils has to always be cleaned with detergent well dried and stored in a very clan place
Producing quality milk will enable farmers to compete in the milk market and succeed at all levels to earn better
revenue. On the other hand it can contribute to safe and healthy food production. Therefore milk producers have
to do their best to produce clean milk and consult professional assistance when ever required.
308
III. Importance of Dairy Recording:
Recording helps the stockowner to get information on individual cows, as well as on entire herd for day to day
decision making and evaluation of his stock management. In it’s wider since, the importance of recording can
be summarised as follows•
Evaluation
Productive and reproductive performance of individual cow, a bulls, herd or farm is evaluated based on the
accurate record kept for the intended goal. Proper recording assist better and economic livestock
management systems. High yielding cow should be supplemented differently from low yielder ones, this
should be done based on the accurate production record kept for each cow, herd etc.
•
Selection
Selecting an animal among the herd for a desired character (milk yield, growth rate, fertility etc) can be
successfully accomplished if proper recording is kept.
•
Planning
Proper planning for mating to avoid inbreeding and stock replacement can be done if accurate record for
the herd is kept. Records provide bases for planning future direction of production and management
interventions to be made.
•
Comparison
The recorded data should provide data to calculate lactation yield, herd average, individual yield etc. so that
comparison between individual cow, herd or breed can be done.
Major Characteristics of Records
Efficient recording scheme must fulfil the following basic characters.
•
•
•
•
Uniformity: Records must be uniform and easily understandable to the owner and public.
Simplicity: The recording scheme must be as simple as possible, and understandable; other wise it may not
be used properly.
Indicative: The record should enable the user to clearly identify and show weather the farm is benefiting
from the herd and how the management is running.
Informative: The recorded data must provide information, which can help the evaluation of management
and its improvement. It should also provide clear information for the decision making
Types of Records to Keep
•
•
•
•
•
•
General information: This includes ownership, animal identification, and breed data etc... Every animal
can be marked by a reliable marking method after birth as soon as possible. This can be accomplished by
ear tagging, notching and naming the animal if their number is too small.
Growth rate and milk production data are some of the important data to be recorded. All cattle kept for
milk production on the farm should be recorded. If there are different breeds or crosses, should be regarded
as a separate group. All cows in a herd should be included in a milking recorded scheme from the day after
first calving. Milk yield should be measured and recorded.
Reproduction: Some of the basic data to be recorded in the reproduction record are - heat detection,
insemination, service date and bull used. Results of pregnancy diagnoses, calving date and drying off date
are also recorded in the reproduction record.
Feed record: Information on the quality and quantity of basal and supplementary feed offered including
feeding period of the herd or individual cow has to clearly indicated in the feeding record.
Input/output: The input/output balance indicates the economic status of the farm. It includes the amount of
feed and drug used and its price, the number of animals purchased Animal, milk or other sales. This will be
analysed and give information on the economic status of the farm.
Recording Frequency and Accuracy:
309
The frequency of recording depends on the nature of the data to be recorded and the objective of the record. For
example milk yields must be recorded daily, while growth records are usually recorded once a month. Generally
daily recording is accurate but expensive. However, records can be taken by the farmer and his family or a qualified
labourer employed for the work.
Record Management and Analysis
Data should be recorded on a standard format and kept in safe place. Analysis is made according to the need and
type of information needed. Data can be analysed annually quarterly or in six month.
Milk Records
Coe Id Number_______________________________________
Breed / Type__________________________________________
Birth Date____________________________________________
Dam Number__________________________________________
Sire Id________________________________________________
Farm Name ___________________________________________
Date / Year
Parity
Calving
Date
Monthly Milk production
Reproduction Recorded
Coe Id Number_________________
Breed / Type___________________
Birth Date_____________________
310
Dam Number__________________
Sire Id________________________
Parameters
Service Date
1
2
3
4
5
6
7
Service per
conception
PD
8
9
Sire used
Service per conception
Gestation length
Calving date
Calf sex
Breed
Calf birth weight
Weaning date
Weaning weight
Breeding Record
Farm Id___________________________
Owner Name______________________
Coe Id
Number
Breed
/ Type
Birth
Date
Service date
Dam
Sire
1
2
3
311
4
5
Exp
Calving
date
Calving
date
6
Daily Milk Record
Daily Milk yield
Co
w
Id
N
1
Calvin
g Date
A
m
2
P
m
A
m
3
P
m
A
m
4
P
m
A
m
5
P
m
A
m
6
P
m
A
m
Weekl
y Total
7
P
m
A
m
P
m
Growth Record
ID N
Birth
Date
Weighing Date
Birth
Weight
312