James D.E. Beaton 1. INTRODUCTION 2. ADVANTAGES OF

James D.E. Beaton
Consultant; Kelowna, B.C. VIW 329, Canada
JOSe Espinosa
Director;INPOFOS, Quito.
1. INTRODUCTION
2. ADVANTAGESOF FERTIGATION
Fertigationis definedasthe additionof fertilizer plant
nutrientsto croplandthroughirrigationwater,This method
of fertilization hasbecomea well-establishedagronomic
practice,
Virtually all liquid fertilizers andmost solid fertlizers
Application of fertilizers through an irrigation system
resultsin many advantagesto growers.However,the advantagesobtainedwill dependon both the type of irrigation systemandthe fertilizer materialbeingapplied.Some
of the recognizedbenefitsinclude:
when dissolvedcanbe appliedvia irrigation systems.The
quality of water,type of fertilizer usedandproceduresfor
introducingfertilizer nutrientsmay, however,be different
1- Applied plant nutrients carried directly to the
root zone.
C
'
for the various irrigation methods,
2-
Thevariouskinds of irrigation wherefertigationis feasible include'
.
3- Lower requirementsand input costsfor energy,
labourand equipment.
flood irrigation, with water flowing under the
influenceof gravity asa sheetor in furrows,
- overheadsprinklers(centrepivot, travellinggun
and solid set)and
- trickle/drip (drippers, emitters,microjets, "T"
tape,etc.).
th
W
d
. fi .1. d. .b .
ateran accompanymgertl Izer IStri utlon over e
field is often unevenwith flood and furrow fertigation. In
suchsystemsthefirst one-thirdof thewateris appliedwithout fertilizer the following one-third of the water serves
as a carrier for the injected fertilizer and the remaining
h' d .
1. d .
on:ement and rapid method of supplying plant
nutrIents.
-
one-t
Ir
IS
app
Ie
WIt
h out
fi ertl
' I Izer.
'
S pnn '
kl
er
Irrigation
..
,
4- Greaterflexibility in choiceof time andrateof
fertilizer application in accordancewith crop
demand,especiallyfor N.
5- Preciseapplication/distributionof nutrients is
usually possible.
6- Red~cedleachinglo~sesandim~ro~edfertilizer
efficiency through tImely applicationsof mobile nutrientssuch asN, particularly on coarse
textured
soils
'
is
commonly
used for providing
andsuited
nutrients
large
areas
while trickle/drip
systemswater
are better
for to
smaller
areas'involving more frequent and precise application of
.
7- Less mechanIcal
damage from traffic on established crops and compaction of susceptiblesoils.
water and nutrients such as N,
8- Combined application with crop protection
chemicals.
The objectivesof this paper are to (a) report advantagesand disadvantagesof fertigation, (b) identify fertilizer materials,both liquid and solid, that are commonly
used in fertigation, (c) indicate the effectiveness of
fertigation and (d) review the generaluse of liquid
fertilizers.
I
9- Improvedcropproductionbecauseof timely fertilizer additionsandsimplifiedculturalpractices,
The financial supportof TessenderloKerley Inc., Phoenix,Arizona in making possiblethis contribution is greatefully
acknowledged,
X Congreso
Naciona/Agron6mico/ II Congreso
deSue/os1996
129
Fertigation and the use of...
-
3. DISADVANTAGESOF FERTIGATION
Potential disadvantages of fertigation that should be
evaluated are:
..
1- FertilIzer nutrient distribution ISdependent upon
water distribution and will be uneven when fields
are not irrigated uniformly. For example, poor
system design and plugged lines, nozzles and
emitters, etc. will result in irregular distribution.
2- Precise nutrient application rates are not always
obtained with the water application system bein~ used: The greatest dif~culties in metering and
uniformity of plant nutrIent dosages are generally associated with flood and furrow irrigation.
. ..
.
3- FertilIzer nutrIents can be lost m runoff water
from irrigated areas.
4-
. .
Tlmmg
. .
of fertilIzer
. .
additions
.
can be disrupted
4. FERTILIZER MATERIALS FOR
FERTIGATION
Most commercial solid and liquid fertilizer products
are suitable for fertigation. A list of criteria to consider in
the choice of a fertilizer nutrient source follows.
1- State of the nutrient source, whether it is in solid or
liquid form, will determine ease of handling and
injection. as well as its storage requirements.
2- Injection method and quantity of material to be
applied.
3- Type of irrigation system including its uniformity,
application efficiency and distribution method.
4- Product stability and compatability
source.
5-
Effect on soil, particularly
if being applied
drip irrigation
to a restricted
soil zone.
with water
by trickle/
by weather factors such as unexpected excessive
precipitation or strong winds in the caseofsprinkler irrigation.
6- Cost of the fertilizer source.
Liquid fertilizers, both solutions (clear liquids) and sus-
5- Investment in injection and ancillary equipment,
especially that required to prevent backpressure
or backsiphonage into potable water sourceswill
likely be necessary.
pensions, offer several noteworthy advantages over solid
materials including:
1- Manufactured products are ready for use upon delivery by the supplier.
6- Upgrading of management skills.sinc~ pers~nnel must fully understand the calIbration of mjection equipment and the operation of the injector, irrigation system, check valves and backflow
prevention equipment.
2- Especially suited for application through trickle/drip
or sprinkler irrigation systems.
..
.
.
3- Excellent carriers of both mlcronutnents and herblcides.
7- Anhydrous or aqua ammonia applied in surface
or sprinkler applied water are subject to volatilization losses.
Nitrogen Fertilizers:
8- Effectiveness of ammonium containing sources
added to the surface of calcareous soils may also
be reduced by volatilization ofN.
9- Corrosion
of irrigation
system components
by
some fertilizer sources.
IO-Stratification or localized concentration near
emitters of immobile nutrients such as P,. K and
some micronutrients.
II-Precipitation and resultant clogging problems
may occur when some fertilizer sources (e.g.
ammonium polyphosphate-containing liquids)
are injected into irrigation waters high in Ca2+,
Mg2+and HCO).
Table 1 lists the principal fertilizer solutions containing solely N that are available for fertigation . Details on the composition and physical properties of these
N solutions are also provided in this table.
Urea-ammonium nitrate solutions (28 to 32 % N)
are among the most popular liquid sources of N for
fertigation purposes. They are usually manufactured
commercially but they can be homemade based on the
composition information given in Table I. It should be
noted that some solid N fertilizers may be treated with
inert conditioning agents which can cause clogging
problems when used in the preparation ofN solutions
for tickle/drip irrigation systems.
. .
.
ApplIcation of anhydrous ammonia or other
fertitizer products containing free NH to irrigation
waters high in Ca2+,Mg2+and HCO - m;iy result in the
precipitation of calcite and/or magne1ite.These precipitates may cause scaling and plugging problems in irrigation equipment including gated pipe, siphon tubes,
emitters, etc. Addition of acid can prevent or correct
these problems.
None of these potential difficulties have seriously restricted the expanding acceptance and usageoffertigation.
New developments in irrigation technology combined with
irrigation and fertilizer management have lead to improved
water and fertilizer use efficiency and consequently attractive economics of this practice.
130
X CongresoNaciona/Agronomico /11 Congresode Sue/os1996
James Beaton
Table I. Composition and physical properties ofN solutions
Non-ammoniated Solutions
AN-20
-Total N"
Nil, %
NII,NO, %
Urea %
Water %
NltraleN%
A",mollla N %
U,eaN%
Spec. grav. @ 60°f
lhl./gal II 60"f
UREA-20 UAN
20
20
281
301
32
39.5
30.5
30
7
7
14
1.28
10.66
2.98
42.2
32.7
25.1
7.4
7.4
15.2
1.3
10.83
443
35.4
203
7.8
7.8
164
1.33
11.06
3.25
3.54
57.2
43.5
56.5
42.8
10
10
20
1.12
9.33
1.26
10.5
lbl.N/gal. 0 60"f
2.1
1.87
Vapor pressure
I A 100 " f
psgw
Alnmonlated Solutions
(typically noll-prelsure)
Crystallization
temp., "f
41
I
52
lIS
I
Aqua Amlnon'a Solutions
UAN-30 UAN-32
I
I
32'
37
16.6
668
41
22.2
65
20
24.4
20.62
25
12.8
11.4
29.6
75.6
75
]()
20.6
1.19
9.91
37
15.8
58.5
7.7
18
10.2
23.2
3.6
1.17
9.75
1.14
9.5
0.912
7.6
0.911
7.59
367
3.61
3.9
1.52
1.52
1
2
10
1
2
56
28
2\
-58
-103
166
11.7
25.3
'Used In colderdil"a'el whe,e lal'I"9 ",ay occur.
'Ge"elally lold al 20'lbN solutio" II"ce 10lneammonia1011
InayoccurhI ha,,(111"9
Source: California Fertilizer Association (1995)
.
The group ofurea-tr1azone
slow release N solu-
tions (TRISERTR, FORMOLENE-PLUSR, N-SURER
and FORM-U-SOLTM containing at least 25 % total N,
could be potentially useful in fertigation for controlling rates ofN supply to crops and/or reducing N leaching losses.
Th
b
I.
ere are severa
d S
Th
h N
1mpo
( )
rt t
an
I t.
so u
-
th t
10ns
th O
a
I
I
supp
h t
---
'"
~
~
try and it is ideally suited for application through all
types of irrigation systems and (b) ammonium
polysulphide or APS (20-0-0-45S) usually added to
~r~pla?ds by way of flood or high-volume sprinkler
1mgatlonsystems.
r
,
polyphosphate
solutions
. .
fert111zer
tended
.
w1th
products
a sample
of
the
.
.
1mga-
..
...
tlon water m the same proport10ns as will occur m the
system.
Orthophosphoric acid has a furthur benefit of
keeping the pH of the fertigation solution low enough
to minimize the formation of precipitates ofdicalcium
or dimagnesium phosphate.
Thr ee soI1
' d P sources,monoammoruum
.
phosphate
At one time, ammonium bisulphite (8.5-0-0-17S)
(10 to 11 % Nand 48 to 55 % PO) diammonium phos-
was a significant low analysis liquid fertilizer source
ofN and S in localized areas close to its point of production.
phate (18-46-0) and ammoniftni phosphate sulphate
(16-20-0) can be dissolved and used to provide P for
fertigation. Attention should be given to the selection
C
...
and ammonium
d 11-37-0)
an.
It should be noted that precipitation of P compounds can occur when ammonium polyphosphate-containing liquids are introduced into high Ca or
Mg water (> 300 ppm). Consequently, a precipitation
test should be conducted beforehand by mixing the in-
y
ot
an
. ey are a ammoruum 10SUp a e or
ATS (12 0 0 26S) h . h . th
t
I
d
W 1C 1S e mos popu ar an versatile S-containing product in the fluid fertilizer indus-
," ",
c
;:;;~::
if~~
" ",;:";~
% PO)
(10-j4-b
B tw
. t I 41
d 44 b
. ht f
e een approx1ma e y
an
y we1g 0
I' d
.
I h
b d. I d
d
so 1 ammoruum su p ate can e 1SS0ve to pro uce
fertilizer solutions containing about 9 % N and 10 % S.
. (17 0 0 7 7 t 8 8C )
C aIcrum
. ru.trat e soIut 10n
- - -. o. a, a
.
m1xture
popular
.'
of calc rum rutrate
.
m some
areas
for
...
and ammoruum
.
.
fert1gatlon
rutrate,
1S
purposes.
Phosphorus Fertilizers:
.1 bl I . .d
Th
.
. II
e mam commerC1a y ava1a e 1qU1 sources
d ti
ti ct . t .
rth
h
h .
.d
f P u t 1.I 1ze
'
or e 19a 10n are 0
op osp or1c ac1
(
h t
d 52 t 54 0/c P 0 )
.
h
merc an -gra e
0
;to
, ammoruum
p osht
I t ' (8 24 0)
I n2 5 h '
.d (68 t 70
p a e so u 10n - - , po yp osp or1CaC1
0
0
Rand TM
of materials free of conditioners
I .
. d.
that impair this requi-
site 1SS0utlon.
Concentrated or triple superphosphateis not normally a satisfactory P source for fertigation becauseof
.
d
d. I .
ti
. .
its ten ency upon
1SS0 utlon to orm a prec1p1tate 0 f
h
h
h
.
d. I .
1ca crum
I
.
.
p
osp
ate
w
. kl Id . I
1Ch can
II .
I ea d to
d
pro bl ems
.
0f
c oggmg m trIC e rIp atera mes an emItters.
It is generally agreed that movement of P from
fertilizer applied to the soil surface at normal rates is
small.
..,
It 1S mterestmg,
.,
however,
.'.
that the concentrated
.
P solutions appl1ed through tr1ckle 1mgatlon systems
.
may move as much as 20 cm hor1zontally and 30 cm
,
vert1ca
IIy from t he em1tter
. dr1p
. pomt,
,
Trade marks of Tessenderlo Kerley Inc.
X CongresoNacional Agronomico / II Congresode SuelosJ996
J3J
Fertigation and the use oj...
Potassium Fertilizers:
.
..
Solid potassiummagnesiumsulphateis the most
widely usedMg additive in suspensions.
The commonly usedSOlIdpotashfertIlIzer salts,
potassiumchloride andpotassiumnitrate, arevery water soluble and thus are readily used as K sourcesin
Micronutrient Fertilizers:
fertigation. Potassiumsulphateis lesssolubleandheating may be requiredfor adequatedissolution.
Potassiummay alsobe providedin variouswater
soluble solid NPK sources.
The variousinorganicsourcesof the micronutrientsB. Cu. Fe, Mn, Zn and Mo are compiledin Table
2. The heavymetalcationsCu. Fe, Mn andZn arealso
suppliedin the form of syntheticchelatesand natural
organic complexes.
Mono and dipotassiumphosphatesolid fertilizers,if they couldbemanufacturedeconomically,would
be attractive sourcesof both K and P for fertigation
purposes..
It is recommendedthat fertigation of Cu. Fe,Mn
and Zn be carried out with trickle/drip irrigation systerns.Chelatesand sulphatesaltsareeffective sources
for this purpose.
Potassiumthiosulphate(KTS) solution with an
analysisof 0-0-25-17Sis compatiblewith most liquid
fertilizers and is well suited for trickle/drip irrigation
and for foliar application. Potassium polysulphide
(KPS) containing22 % K20 and23 % S is anotherrelatively new liquid K sourcewhich hashadlimited usein
fertigation.
. t and
Although C1 IS
. an essen
t Ia
. I pIant nutr Ien
. Favo.urab.'e
~esults.,,:ith foliarly appliedNZNTM
mtrogen-zmclIqUIdfertIlIzer (15-0-0-5Zn)havebeen
recorded and it will likely perform satisfactorily in
fertigation applications.
Table 2. Inorganic sourcesof micronutrients
-
high concentrations are beneficial for some crops, C 1free K fertilizer materials a~epreferred for fruit crops
and strawberries which are sensitive to this nutrient.
Sulphur
Fertilizers:
.
.
The prmclpal
.
sources of plant nutrIent
S are
multi-nutrient products which are noted in each of the
sections on N P 9 M g and micronutrients Although
.
. ,
.
APS is an excellentsourceof
Plant nutrient Sits Pri-
Malerl.1
sou",e. of boron
Granular boraK- Na,B.O,oIOH,O
Sodium lelraboral.. anh!"!rous - Na,B,O,
Soluborf1)- Na,B.O,,04H,O
Ammonium
penlaboral.
- NH,B,O.04H,O
Sou",..
- Cu50.-5tl,O
Cuprouschloride- Cu,CI,
Cupric
Chlorld.)CuCI,
ment. ATS also has favourablesoil amendment
Source. of Iron
P
ro
p
erties
,
-
F.rrous
sulfate
Forrous
sulfate
F.rrlc sulfal.
Calcium Fertilizers:
-
F.SO,oH,O
- F.,(SO,J,o9H,O
-
F.SO,o7H,O
Ironoxalate
- F..(C,°.J,
-
CalCIUm chloride (approximately 27 % Ca and
53 % C I) and calcium nitrate (referred to previously)
pplication throu gh trickle/
are two materials capableof a
F.rrous ammonium sulfate
Fe(NH,J,(SO,J,06H,O
-
F.rriC
chloride
- FeCI,
- MnSO,04H,O
-
Manganous
5ulfat.
drip systemsandwhichwill likely be effectiveunder
acId soIl conditIons.
Manganous
oxide- MnO
.
..
,
MagnesIum
, ,
FertIlIzers:
C1), magnesium chloride solution (8 to 9 % Mg), mag(170
. cheIates(2 to
,
.
neSIUm
mtrate
. - 145M
g), synthetlc
plexes(4 to 90;<M g)
4 % Mg)
andnaturalorganic com
,
0
aresatIsfactoryMg sourcesfor fertigationapplicationsNItrogen-magnesium
33
32
86
199
7
(,'\
250
2"
888
798
6"2
I'
I'
1.5
liquid
fertilizer
or NMGTM
(14-0-0-4Mg) is another possible Mg source for
71
:12
31"
80
(,0
201
33
32
199
300
142
344
440
68
18
32
105
32
very'oluhl.
74
-
Manganouschloride - MnCI,
246
478
720
43 7
00065
32
I'
77
63
32
397
56
32
543
4"
364
89
774
Sodiummol~al.-Na,MoO,oH,O
Ammoniummolybdate-
(NH,J.Mo,O"oIH,O
Mol~lc
SoU"'"
oKId.
- MoO,
66.0
01\
77
r",
0 f zinc
Zinc,ulfal.-ZnSO,oH,O
ZlncoKld.-ZnO
ZInc
carbonat.
- Znco,
ZIncchloride- ZnCI,
Zinc oxysulfale - Zno-ZnSO,
803
52.\
480
53.8
I'
0.00\
432
-
212
60
77
-
ZIncammonium
sulfat.ZnSO.o{NH,),so,06H,O
ZIncnltrale-Zn(NO,J,06H,O
\6.3
22.0
9.6
324
"'.-'-"""'"_."'"
Source:California Fertilizer Association(1990).
132
77
"72
fertigation.
TM
:12
sourc.. of molybdenum
phate or epsom salts(9.6 % Mg
Magnesium sul
and 13 % S), magnesium chloride (20 % M g and 74 %
,
2.5
13
22
Sourc..
ofmangan...
Manganous
carbonate MnCO,
Mangan...oKlde Mn,O,
-
113
215
205
of copper
Copper sulfate
Cuprous
oKlde
- Cu,O
CuprIc
oKtd.- CuO
mary uses are as a soil amendment and for water treat-
,
Elemenl Waler
Solubllily 'F
($1
(g/1009 HPI
Trademarkof Tessenderlo
KerleyInc,
X Congreso
Naciona/Agronomico/ II Congreso
deSue/os1996
32
68
James Beaton
5. FERTILIZER CONCENTRATIONIN
IRRIGATION WATER
7. CROPSBEING FERTIGATED
Fertigation, especially by trickle/drip systems, is usually confmed to high value crops including tree fruits, vegetables, small fruits and berries, flowers, horticultural and
floricultural production in greenhouses and in nurseries.
Although susceptibility to root burning from concentrated fertilizers varies with crops, ferblizer sources and
irrigation practices, the concentration of a given fertilizer
material in irrigation water should not exceed 5 %. It is
generally agreed that fertilizer concentrations of I to 2 %
at emitters is acceptable.
6. STARTING
AND
ENDING
8. EFFECTIVENESS OF FERTIGATION
In addition to the many advantages that fertigation has
on farm and water management generally, crop yields are
FERTILIZER
INJECTION
alsoimprovedsignificantly.Onthebasisoffield trialscon-
Th
ducted in many parts of the world, this practice will raise
I I.
h Id b fill d fi
t1 t5 . t
e supp y mes s ou
e I e or a eas mmu es
.
before
startmg
t.
mue
...
mjectlon.
When
mjectlon
th th . . t.
.
runnIng
e
e Imga
IS
t
Ion
wa
fi
er
30
or
completed
.
mmu
con-
t
es
.
m
or-
der to (a) clear the system of fertilizer solution, Ib) provide
.
.
Yields
.
at
I fi
tlona
.
ertl
least
10
.1"
Izatlon
%
met
above
h d
0
those
s suc
h
obtamed
as
b
an
d.
mg
.
with
and
conven-
broadcast-
mg.
even
distribution
of applied nutrients and (c) avoid clogging of
lines and emitters.
-I=
u.J
55
<..>
0::
u.J
a..
50
45
u.J
0::
<C
40
35
=
~
30
Iu.J
'""
0::
<C
~'5
25
20
BAGGED
, 0
5
'965
-IN
1970
C L U DES
AN
'975
H YD R 0
USA
1980
M M 0 N IA
1965
1990
5
Figure 1. Fertilizer use by class in the United States- 1965 to 1995 (Terry et al., 1996)
IZ
w
70
(.)
[!:
w
60
Co
w
DRY BULK
50
[!:
<
:I:
40
(/)
~
w
30
~
[!:
20
<
~
10
0
1965
1970
Figure 2. Multi-nutrient
1975
19BO
1985
1990
1995
fertilizer use by class in the United States-1965 to 1995 (Terry et al. , 1996)
X CongresoNaciona/ Agronomico III Congresode Sue/osJ996
J33
Fertigation and the use of...
Tickle/dripirrigationcanalsohavea majorimpacton
improvingwateruseefficiencyby 30 % or more.
10. REFERENCES
9. LIQUID
Beaton,J.D.,L.S.Murphy,E.H.HalsteadandJ.C.W.Keng.1992.Recent
NORTH
.
United
FERTILIZER
DEMAND IN
AMERICA
S
f
'
tates 0 America:
SaoPaulo.
After a modest beginning in California in the early
1920's, the U.S. liquid fertilizer market grew slowly
until the decadeof the 1950's when it expanded rapidly
in the Midwest and Pacific Northwest. Plant nutrient
.
consumption
of
..
liquid
. .
fertilizers
.
Increased
at the
rate
of seven % annually during the 1970's and early 1980's.
This growth rate exceeded the 4% annual gain in total
plant nutrient consumption which occurred during the
.d
In 1980
.'
17 % of the fertilizer
.
"
consumed
in the
U.S. was m the form of liquid products. Fifteen years
later in 1995, liquids ( including anhydrous ammonia)
accounted for 40 % or 18.4 million metric tons of the
46 million tons of. fertilizer materials consumed
.
I).
CaliforniaFertilizerAssociation.1990.WesternFertilizerHandbook.
HorticultureEdition. InterstatePublishers,Inc., Danville,
Illinois.
California
Fertilizer
8th Edition.
Association.
1995. Western Fertilizer
Handbook.
Interstate Publishers, Inc., Danville,
Illinois.
Hauck,RolandD. 1984.Nitrogenin CropProduction.
AmericanSociety
of Agronomy,
CropScience
Societyof AmericaandSoilScience
Society of America, Madison, Wisconsin.
same perlo .
.
(Figure
developments and trends in fertilization techniques with
particular referenceto fluid fertilizers. XX Brazilian Meeting
on Soil Fertility and Plant Nutrition. July 27, 1992.Piracicaba,
Anhydrous
ammonia
represented
3.95
Korol, Mau.rice and Lynn Girard. 1996. Canadi~ fertilizer consu~ption,
shipments and trade 1994/95. Agriculture and AgII-Food
Canada,
PolicyBranch.Onawa,Ontario.
Randall,GylesW., K.L. Wells andJohnJ. Hanway.1985.Modern
techniques
in fertilizerapplication.
p.521-560.
In O.P.Engelstad
et al.. (ad.). Fertilizer Technology
and Use. Third
Science Society of America, Madison, Wisconsin.
edition.
Soil
million metric tons of this total liquid fertilizer usage.
.
.
Multi-nutrient
..
. .
liquid fertIlizers
.
or those contam-
ing either N-P-K, N-P, N-K and P-K, were first marketed in the U. S. about 40 years ago. Subsequently,
I' .d fi rt'l'
. tu
h
. d
.d bl
Iqui e Ilzer mix res ave game consI era e acceptance as revealed in Figure 2. Since the early 1980's
they have had about a 20 % share of the total
multi-nutrient market which was 16.7 16.0 17.1 and
ll '
tr . t
. 19901991' 1994' d 1995
16.9 m'I Ion me IC onsm
,
,
an,
respectively. They are also becoming popular in other
parts of North America, particularly Canada.
Tally, D.L., Paul Z. Yu and Henry S. Spencer. 1996. Commercial
Fertilizers 1995. The Association of American Plant Food
ControlOfficials.Lexington,Kentucky.
Tisdale,S. L., W.L. NelsonandJ.D. Beaton.1985.Soil Fertilityand
Fertilizers.Fourthedition.MacmillanPublishingCompany.
NewYork,N.Y.
Tisdale,S.L.,W.L.Nelson,J.D.BeatonandJohnL. Havlin.1993.Soil
Fertility and Fertilizers. Fifth edition. Macmillan Publishing
Company.
NewYork,N.Y.
Canada:
van der Gulik, Ted W. 1987.B.C. Trickle IrrigationManual.B.C.
Ministry of Agricultureand Fisheries,Abbotsford,British
Columbia.
According to the 1986 Censusof Agriculture, Canadian farmers used nearly 4 million metric tons offertilizer products. Of this total, 78 % was in solid forms,
van der Gulik, Ted W. 1993.ChemigationGuidelinesfor British
Columbia.B.C.Ministryof Agriculture,Fisheries
andFood,
Abbotsford,
BritishColumbia.
13 % as pres~uriz~d liquids (anhyd!ous ~~onia and
aqua ammonia), 8 Yoas non-pressurized liquids and 0.7
% in the form of suspensions. In 1995, nitrogen and
ammonium polyphosphate solutions accounted for at
Waterman,PeterF.I994.FertilizationGuidelinesinHighDensityApp
and Apple Nurseriesin the Okanagan-Similkameen.
B.C.
Ministryof Agriculture,
Fisheries
andFood,Abbotsford,
British
Columbia.
l~ast 6 %.ofthe total fertilizer cons~mption of 4.6 million metric tons. Anhydrous ammonia usageof 553,727
metric tons represented 12.1 % of total fertilizer usage
in the same year.
Wolf, B., J. FlemingandJ. Batchelor.1985.Fluid FertilizerManual.
Volume I and2. NationalFertilizerSolutionsAssociation,
Peoria,Illinois.
The authors were unable to provide an estimate
of the proportion of liquid fertilizers applied through
fi
134
.
.
ertlgatlon
.
.th
m el
er country.
Young, Ronald D., D.G. Westfall and Gary W. Colliver. 1985.
Production,marketinganduseof phosphorus
fertilizers.p.
323-376.172.0.
P.~~gelstad.et
al: (ad).Fert~lizer
Technol~gy
and Use. Third edition.
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Soil
X CongresoNacionalAgronomico / II Congresode Suelos1996
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of America,