Nchima Malawi Alfred Hartemink

SOIL FERTILITY STATUS OF
NCHIMA ESTATE
—Malawi—
A.E. Hartemink
1990
ISRIC LIBRARY
Wl - 1990.01
01
Wageningen
The Netherlands
ISRIC LIBRARY
ÏU+L
^>-Ol
Wageniogen, T h . Netherlands
SOIL FERTILITY STATUS OF
NCHIMA ESTATE
WÊÊ - M a l a w i - WÊÊÊ
A.E. Hartemink
1990
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9QIL FgflTLTTY STATU9 OF NCflIMA B3TATE IN 1997
1 INTRODUCTION
2
2 SOIL FSETTLITY STATUS
2.1 General Trend
,
,
2
2
2.2 Tea and the Soil Fertility Status
3
2.3 Coffee and the Soil Fertility Status
4
3 RECOMMENDATIONS
4
3.1 Tea
.4
3.2 Coffee
5
ANNEXES:
Annex 1 Analytical Data of Samples
6
Annex 2 Keys to Soil Depth, Soil Reaction Classes and General Ratings
of Soil Fertility Parameters
•'
8
1
i
f
i imvwmw
This report concerns an interpretation of the soil analysis report of Nchima
Estate with reference to tea and coffee cultivation. It was written at the
request of Mr. K.P. Legg by Mr. A.E. Hartemink in August 1990. The soil
analysis report gives the data of 74 samples taken from selected fields in
August 1987.
The purpose of this report as to provide the Nchima management with
information about the soil fertility conditions of the fields and to provide
them with some fertilizer recommendations for tea and coffee. Hereto the data
were compared with the chemical soil requirements of tea and coffee.
Constraints in the interpretation were:
-unknown depths and methods of sampling
-^unknown methods for soil analysis
-CEC and texture are not determined
-data are three years old
Especially this latter constraint made that detailed and actual valid
recommendations on the fertilizing management of individual fields could not
be made properly.
2 .gpH, mniwy spws
2.1 General Trend
The analytical data of the soil samples are given in Annex 1, a summary with
the highest and lowest values of the top- and subsoil is given below:
Summary of Chemical Data of Soils at Nchima Estate, Highest and
Lowest Values.
depth pH H20 Avail. P
ppm
Exchangeable Cation meq%
K
Ca
Mg
Loss on
ign. %
topsoil 3.8-5.5 tr. - 137 0.03-0.79 0.18-0.84 0.03-0.65 4.1-12.3
subsoil 4.3-5.8 tr. - 27 0.20-0.62 0.19-0.94 0.11-1.31 3.1-13.4
Wi£h only a few exceptions can be stated that the soils of Nchima Estate have
an extremely to very strongly acid soil reaction (pH).
Exchangeable cations are low for potassium, very low for calcium and very low
or low for magnesium.
Available phosphorus levels tend to vary considerably but most soils are not
very well supplied with this element. In some soils it is completely absent.
Rirthermore in very acid soils phosphorus is precipitated into compounds of
low solubility. The lower the pH, the higher the exchangeable aluminium level
and the larger the P-fixation.
The organic matter contents (expressed in loss on ignition) are satisfactorily
though the method applied for analyzing tends to overestimate the contents.
Remarkable is the little difference in organic matter contents of the top- and
subsoil.
2
I
The chemically richest soils are in the fields: Abram 1&2, Chil, Nankh, Oof f
and Kab i/ii/iii/iiig. In these soils the pH is generally higher (between 5.0
and 5.5) and potassium levels are generally moderately. Levels of phosphorus,
magnesium and calcium are low.
The chemically poorest soils are in the fields: 4, 6, 7, 10, chiwale,
nkolokosa, no.l top and no.3. In these fields the soils have an extremely low
pH and low or very low levels of exchangeable cations.
The low pH may be due to continuous cultivation without replenishing of
nutrients or as consequence of applying fertilizers with a net acidifying
effect.
2.2 Tea and the Soil Fertility Status
The fertility conditions of many soils are favourable for tea cultivation
despite the fact that the soils are very strorgly acid. It is very likely that
with these soil reactions the aluminium availability is high and as tea is an
aluminium accumulator, the acid soil properties are generally favourable.
Nevertheless, attention must be paid to soil pH, because increasing soil
acidity may induce deficiencies, mainly of potassium and phosphorus, sometimes
magnesium and molybdenum. Moreover an increasing soil acidity inclines losses
due to leaching and it reduces the efficiency of fertilizer applications.
However, liming of tea soils is not recommended as calcium requirements of tea
are rather low and lime hinders the uptake of potassium.
It is assumed that the organic matter is able to release sufficient nitrogen
after the onset of the rains when it is mineralizing. This nitrogen flush does
not cover the entire needs of the tea plants in the growing season and
nitrogen fertilization is therefore required some period after the onset of
the rains. An application of 90 kg N/ha per year is considered as the minimum.
The phosphorus levels are very much varying which explains the variable
response to phosphorus explanation in tea in the Cholo district as reported by
the TKF of Central Africa (1979). Nevertheless an application of 30 kg of P205
(13 kg P) should be given annually per hectare to all areas where NPK
fertilizer is not used. In some fields where phosphorus is absent (no.4, chil,
nankh, nched, trott etc.), the application may be increased to 50 kg of P205
per hectare.
The potassium levels of the soils are not
sufficient to cover the
requirements of the tea crop. The onset of potassium deficiency will be
hastened by the use of of nitrogen fertilizers alone, particularly sulphate of
ammonia or CAN, and by removal of prunings from the field. To prevent
potassium deficiencies affecting yield, potash fertilizer should be applied to
all tea on soil of pH 5.8 and lower. In other words, all tea of Nchima Estate
requires potash fertilization.
Magnesium levels are very low in all soils of Nchima Estate. Usually there is
no evidence of any need for magnesium fertilizer in tea. Magnesium deficiency
arises frequently as a result of poor root development due to lack of
potassium, not because of lack of available magnesium in the soil. It was
found that correction of the potassium deficiency leads to the disappearance
of the magnesium deficiency also.
3
2.3 Coffee and the Soil Fertility Status
The pH (or soil reaction) of most soils is too low for Cofféa arabica
cultivation. With these soil reactions aluminium becomes readily available are!.
may be taken up by the coffee trees in toxic amounts. It is therefore that the
crop is rarely grown on soils with a pH below 4.5 where aluminium toxicity
could be serious. At Nchima, liming is required for successful coffee
cultivation.
Provided that all the conditions are right for the coffee tree -management,
soil moisture and no elements are deficient- then the available nitrogen has
the greatest effect on yield. Under most conditions where coffee trees are
grown without shade and produce heavy crops, regular applications of nitrogen
fertilizer are essential. Conversely, coffee growing under heavy shade rarely
responds to the application of nitrogen fertilizer. As the soils of Nchima are
not very well supplied with other major nutrients (e.g. potassium), nitrogen
fertilization only . induces nutrient imbalances and hence deficiencies.
Moreover the crop becomes susceptible to diseases.
The coffee tree requires comparatively little phosphorus and coffee appears to
have a remarkable ability to take up the amount of phosphorus it needs even
when the level in the soil is low. However, for root growth and flower
development an adequate level of available phosphorus is vital. As most soils
of Nchima have levels below 10 ppm, phosphorus applications is required to new
plantings, and for productive plantings after the harvest period is complete.
Like many tropical fruit crops, coffee has a high level of potassium uptake.
Potassium usually becomes inadequate when the trees are bearing a heavy crop
and this is likely to occur as most soils have very low potassium levels.
There is a striking response of such coffee trees to a heavy application of
potassium fertilizer.
Magnesium deficiency is most often caused by a relative potassium excess under
the influence of a K/Mg antagonism. As K and Mg levels are low in the soils of
Nchima, magnesium deficiency is not likely to occur. Potash application to the
coffee crop may lead to magnesium deficiency. The quickest way to cure the
deficiency is to spray three to seven times with a 1-2 % solution of Epsom
salt at fortnightly intervals.
3 RBOOMMENDATIQNS
As a new fertility survey will be conducted in October 1990, recommendations
as given here are preliminary only. Detailed fertilizer recommendations in
kg/block will be given after the new soil analysis has been carried out. This
will be based on the availability of the different types of fertilizers in
Malawi.
3.1 Tea
- Urea is not a suitable fertilizer for tea at Nchima. At first it increases
the soil acidity and secondly, as there is usually a surface mulch of leaf
litter under the tea bush, a high percentage of nitrogen gets volatilized
after application. Hence urea might be more expensive per kg N than NPK
fertilizers.
4
- On extremely acid soils (field 4, 10) one may consider erecting fertilizer
trials with CAN in order to avoid the acidifying effect of using urea or SA.
But this fertilizer should only be applied in combination with a potassium
fertilizer. The calcium in the CAN gives rise to potassium deficiencies.
- A compound fertilizer with a NPK ratio 25-5-5 or 20-10-10 is the most
suitable fertilizer for the tea at Nchima Estate preferably given in split
application after the onset of the rains. On soils with very low potash and
phosphorus levels, 20-10-10 should be preferred.
If no compound fertilizers are available, a combination of the following
single fertilizers are recommended: CAN alternately used with SA, Muriate of
Potash and di-^ammonium phosphate (or single, double or triple super
phosphate).
3.2 Coffee
- Based exclusively oh the soil analysis report of 1987, it can be concluded
that there are only a very few sites (i.e. Kablll and KablllG) with a fair
fertility for coffee cultivation. For most lands the soil fertility is
affecting successful coffee cultivation. New coffee plantings are only
recommended with an uplift of the soil fertility by means of liming, organic
manuring and/or NPK fertilizing.
- Liming to pH 5.0/5.5 on the extremely acid soils in order to improve the
suitability for coffee cultivation is required. An application of
3-5 tons/ha of dolomitic limestone (containing Mg) every three year is
recommended. The lime application induces unfavourable calcium/potassium
ratios and it should be accompanied with muriate of potash applications.
- For young coffee a N/P205/K20 ratio is preferred with the accent on P. e.g.
a 1:2:1 ratio whereas for coffee in production an N/P205/K20 ratio of 2:1:2 is
recommended.
- For the existing coffee plantings fertilizing with hulls and pulp as a good
source of potassium is recommended. In addition CAN may be used as a'N source.
The fertilizer should be applied in a circle from 30 to 90 cm around young
coffee or in a band about 60 to 90 cm wide between rows of mature coffee.
Heavy dressings of pulp and hulls leads to magnesium deficiency symptoms and
spraying with Epsom salts may be required..
- Urea and SA are unsuitable for fertilizing the.coffee at Nchima Estate. CAN
is more suitable but it should not be applied without potash fertilizers.
- Foliar analysis for existing coffee plantings» and soil analysis for new
areas are the most appropriate ways to determine the nutrient* disorders and
their cure.
5
Annex 1 Analytical Data of Samples from 1987
field
block depth pH H20 Avail. P
4
4
4
6
6
6
7
7
10
10
4
9
15
5
7
13
2
5
6
9
chipatala
3
chipatala
5
chipatala
7
chipatala
10
chiwale
1
chiwale
3
malinga moy
1
malinga moy
3
nkolckosa
2
nkolokosa
6
peters
4
peters
7
v.p. tea
2
v.p. tea
5
no.l top
no.l top
no.2
no. 2
no.3
no.3
no.4
no.4
abraml
abraml
abram2
ahram2
chil
chil
no.l low
no.l low
nankh
nankh
nched
nched
off
off
trott
trott
beat
beat
tr. - traces
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoi1
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
4.3
4.4
3.8
4.1
4.4
4.4
4.0
4.2
3.9
4.2
4.7
4.0
4.8
4.2
4.2
5.0
4.5
4.4
3.9
4.4
4.5
4.0
4.8
4.7
4.1
4.3
4.5
4.6
4.2
4.5
4.5
4.7
5.4
5.3
5.1
5.6
5.3
4.9
4.2
4.5
5.2
5.0
4.8
4.8
4.7
4.5
4.5
5.0
4.5
5.0
ppm
Been. Cations meq% Loss on
Hg ign. %
K
Ca
25
5
41
3
32
2
130
10
37
1
10
2
2
18
8
5
14
1
3
6
48
137
18
5
52
14
41
7
5
14
tr.
3
19
2
15
2
5
tr.
3
5
3
tr.
2
tr.
22
2
6
tr.
3
tr.
0.09
0.20
0.20
0.18
0.30
0.16
0.11
0.14
0.11
0.23
0.31
0.33
0.35
0.16
0.11
0.03
0.16
0.32
0.22
0.13
0.12
0.28
0.29
0.30
0.25
0.16
0.27
0.20
0.25
0.20
0.53
0.37
0.55
0.40
0.55
0.52
0.69
0.35
0.25
0.30
0.47
0.24
0.49
0.28
0.21
0.20
0*43
0.37
0.47
0.40
0.23
0.28
0.25
0.15
0.28
0.23
0.33
0.23
0.20
0.19
0.33
0.23
0.40
0.20
0.18
0.43
0.43
0.28
0.28
0.19
0.28
0.26
0.23
0.35
0.58
0.19
0.26
0.36
0.20
0.34
0.36
0.50
0.60
0.45
0.49
0.49
0.77
0.43
0.24
0.45
0.44
0.41
0.41
0.37
0.19
0.29
0.37
0.52
0.30
0.52
0.06
0.10
0.04
0.04
0.08
0.07
0.05
0.04
0.01
0.14
0.26
o.u
0.32
0.03
0.04
0.16
0.08
0.09
0.06
0.09'
0.09
0.06
0.19
0.36
0.05
0.11
0.12
0.19
0.11
0.22
0.26
0.37
0.59
0.42
0.39
0.45
0.59
0.29
0.25
0.47
0.30
0.34
0.51
0.64
0.15
0.34
0.41
0.63
0.34
0.61
7.0
6.5
10.2
6.2
8.5
5.8
5.7
8.8
6.4
10.1
9.5
7.6
7.2
7.4
5.2
4.1
8.4
8.9
10.8
6.3
5.5
7.8
6.9
6.8
6.4
6.6
7.1
7.2
10.2
13.4
10.7
10.5
12.3
11.0
7.8
8.8
8.3
9.7
7.6
7.7
7.2
8.5
9.5
8.1
8.0
8.7
11.1
10.0
9.0
9.7
Annex 1 Analytical Data of Samples from 1987 (continued)
field
block depth pH H20 Avail. P
ppm
coff
coff
chip
chip
jull
jull
kabl
kabl
kabll
kabll
kablll
kablll
kabIII/85
kabIII/85
kablllG
kablllG
kad2
kad2
t22
t22
t25
t25
west
west
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
topsoil
subsoil
5.2
4.9
4.6
5.1
4.8
5.1
5.3
5.8
5.2
5.3 -
5.5
5.5
4.8
4.9
5.4
5.5
4.6
4.8
4.8
5.0
4.3
4.8
4.5
5.0
25
8
5
tr.
6
tr.
15
tr.
1
tr.
1
tr.
7
tr.
3
2
52
27
29
2
15
2
28
1
7
Exch. Cations meq% Loss on
K
Ca
Mg ign. %
0.39
0.53
0.56
0.32
0.53
0.48
0.62
0.60
0.63
0.39
0.79
0.62
0.27
0.53
0.21
0.33
0.50
0.34
0.43
0.29
0.21
0.20
0.46
0.37
0.50
0.43
0.45
0.61
0.47
0.71
0.84
0.72
0.38
0.40
0.69
0.58
0.40
0.41
0.43
0.30
0.69
0.94
0.65
0.77
0.43
0.73
0.53
0.83
0.60
0.42
0.31
0.51
0.53
0.62
0.60
0.64
0.34
0.62
0.63
0.51
0.62
0.57
0.46
0.34
0.65
1.31
0.58
1.19
0.30
0.89
0.52
1.25
7.7
7.9
9.9
10.1
8.0
9.7
6.9
8.9
6.6
6.5
8.4
9.1
7.4
6.8
4.1
3.1
7.0
7.0
7.4
8.5
8.0
8.7
9.2
8.6
Annex 2 Keys to soil depth, soil reaction classes and general Ratings
of Soil Fertility Parameters
thickness topsoil
very thin
thin
mod. thick
thick
very thick
cm
thickness solum
<10
10-20
20-30
30-40
M0
cm
very shallow
shallow
mod. deep
deep
very deep
1]
<25
25-50
50-80
80-120
>120
soil react:.on (pH-water)
extremely acid
<4.5
v. strongly acid 4.5-5.0
strongly acid
'S.l^ö.S
mod. acid
5.6-6.0
slightly acid
6.1-6.6
v. low
% organic matter
<1
C/N
CEC me/100g
BCBC me/lOOg
exch. Ca me/100g
exch. Mg me/100g
exch. K me/100g
% base saturation
% Al saturation
avail. P (Bray I)
<6
<4
<2
<0.3
<0.1
<20
neutral
6.7-7.3
mildly alkaline 7.4-7.8
mod. alkaline
7.9-8.4
strongly alkaline 8.5-9.0
v.strongly alkaline >9.0
low
mod
high
1-2
<10
2-4
4-6
>15
>6
25-40
M0
6-12
4-8
2-5
0.3-1
0.1-O.2
20-40
<20
<7
10-15
12-25
8-12
5-10
>12
10-20
1-3
3-6
0.2-0.4
40-60
20-40
7-20
0.4-0.8
60-80
40-60
8
v.high
>20
>20
>6
X).8
>80
>60
.