Improving Soil Fertility and
Nutrient Management in
Developing Countries
K.F. Bronson
Texas A&M and Texas Tech University
Outline• World fertilizer consumption/crop production
– 1961-2002/malnutrition
• Green revolution & fertilizer
• Soil organic matter build-up & fertilizer
• Fertilizers and the environment
• Nut mgt in Asia
-- Central Asia
-- South Asia
-- SE Asia
• Nut mgt in Africa
-- West Africa
• Future needs for research and outreach
Fertilizer use and crop
production worldwide
0
500
1000
1500
2000
2500
1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000
Year
Ce
rera
l p
rod
uc
tio
n (
mil
l M
t)
0
20
40
60
80
100
120
140
160
Fe
rtil
ize
r c
on
su
mp
tio
n (
mil
l M
t)
Cereal production
Fertilizer consumption
World cereal production and total fertilizer
consumption, 1961-2002 (FAOSTAT)
Africa is an exception
Production
per capita
and
Production
Area per
capita
0
5
10
15
20
25
30
35
40
45
Devg Asia India Bang China Indo Sub-Africa Niger Mali S.A. Brazil Colum
Countries
Pe
rce
nt
of
po
p u
nd
ern
ou
ris
he
d
1990-1992
1999-2001
Percent of population malnourished for 1990-2001
0
500
1000
1500
2000
2500
3000
3500
Devg Asia India Bang China Indo Sub-Africa Niger Mali S.A. Brazil Colum
Countries
Ca
lori
es
/pe
rso
n/d
ay
1990-1992
1999-2001
Calories/person/day for 1990-2001
Note: World avg 2700-2800 cal, USA avg 3500-3800 cal
Fertilizer and the green
revolution
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
0 20 40 60 80 100 120
Nitrogen rate (kg/ha)
Gra
in y
ield
(t/
ha
)
Tall, native variety
IR8
Response of tall, traditional rice and semi-dwarf rice to
N fertilizer, Philippines, 1968
“African Exception” (Avery, 2000)
• Africa has been low population with low input/low yield bush fallow. 25 % good cropland not used
• Green revolution efforts targeted Asia, were not transferable to Africa
• Poor record keeping
• Poor governance
Why hasn’t the green revolution been
successful in Africa? (Evenson&Gollin)
• No elite germplasm for cassava, beans
sorghum, millet
• Crops are more diverse & mostly dryland
• Large landholdings for cash crops
Fertilizer and soil organic matter
Nutrient management
Total organic C Total N
g/kg mg/kg
Control 5.1 c 422 f
N 5.7 d 660 d
NP 6.3 c 750 c
NPK 7.4 b 867 b
NPK + FYM 7.9 a 927 a
Total soil organic C and total soil N in 0-15 cm
Inceptisol after 30 yr of rice-wheat-jute cropping,
West Bengal, India (Manna et al., 2006)
Crop residue removal
Advantages of organic manures
• Boost yields, retard yield declines
• Provide N, P, micronutrients
• Fortify seeds with micronutrients
• Build-up soil organic matter
• Improve soil physical properties
• Improve soil water relations
Limitations of organic manures
• Availability/transport costs
• Nutrient imbalance (i.e. manure is about
2:1 N:P2O5, plants need 5-7:1 N:P2O5)
• Variability in composition
• Potential for polluting surface waters
• Limited nutrient availability in 1st year
• Pathogens
Fertilizer and the environment
Nitrous oxide fluxes in irrigated rice as affected
by N fertilizer source and mid-season drainage,
Los Banos, Philippines, 1993 dry season.
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
0 20 40 60 80 100 120
Days after transplanting
N2O
(m
g N
/m2/d
)
Urea
Ammonium sulfate
-5
0
5
10
15
20
25
30
35
40
0 20 40 60 80 100 120
Days after transplanting
CH
4 f
lux
(m
g C
/m2/d
)
Urea
Ammonium sulfate
Methane fluxes in irrigated rice as affected by
N fertilizer source and mid-season drainage,
Los Banos, Philippines, 1993 dry season.
Cadmium content of phosphate rock
mg/kg mg/kg P2O5
Igneous Deposits
South Africa 1 3
Former USSR 1 3
Sedimentary Deposits
China 2 7
Morocco 26 80
Senegal 87 241
North Florida 6 20
North Carolina 38 128
Western US 92 292
Other environmental issues
• Eutrophication of surface waters
• Nitrate contamination of surface and
ground waters
• Arsenic contamination of groundwater
• Aral Sea crisis
Soil Fertility in Asia
0
20
40
60
80
100
120
140
160
19671969
19711973
19751977
19791981
19831985
19871989
19911993
19951997
19992001
2003
Year
Ric
e a
nd
wh
ea
t p
rod
uc
tio
n (
mil
ln M
t)
0
2
4
6
8
10
12
14
16
18
20
Fe
rtil
ize
r c
ion
su
pti
on
(m
illn
Mt)
Rice production
Wheat production
Fertilizer consumption
Fertilizer use and grain production in India
Chlorophyll meter and leaf color chart for in-
season N monitoring in Asia
N management
Total N applied
Cultivar
kg N/ ha PR-106
PR-111
---------- Mg ha-1 ----------- Well-fertilized reference
240 5.80 a 7.02 a
Chlorophyll meter-based
90 6.08 a 6.51 a
Fixed-timing 120 6.14 a 6.54 a
Zero-control 0 4.42 b 4.72 b
Rice grain yields as affected by
chlorophyll meter-based management,
Ludhiana, India, 1997
Urea and single
superphosphate fertilization
in Eastern Uzbekistan
Uzbek farmers fertilization survey
• What is your cotton seeding rate (kg/ha)? 60
• What is your seedcotton yield goal (t/ha)? 2.9
• How much total urea do you apply (kg/ha)? 488
• How much superphosphate do you apply (kg/ha)?
421
• How much potash do you apply (kg/ha)? 32
Uzbek farmers’ survey for wheat
• What is your wheat seeding rate (kg/ha)? 250
• What is your yield goal (t/ha) ? 4.3
• How much urea do you apply (kg/ha)? 452
• How much superphosphate do you apply (kg/ha)? 419
• How much potash do you apply (kg/ha)? 3
• How often is your soil sampled and tested at the local lab? No (100%)
Quva (11) Bagdod (12) Okhunboboev (12)
Low Med High Low Med High Low Med High
Nitrate 100% 100% 66% 34%
P 55% 45% 100% 34% 34% 34%
K 18% 82% 100% 100%
1:1 pH 7.7 (0.4) 8.1 (0.2) 8.0 (0.2)
ECa (mmo/cm)
6.0 (0.6) 2.0 (0.2) 1.8 (0.3)
airrigation water
Soil test results from three districts in Ferghana
valley, March, 2003
Establishment of N and P fertilizer
rate trials in 2005
• Three locations (Quva, Ristan, and Bagdod)
• Soil tests (LaMotte) done 0-15 cm
• RCB design, N x P factorial, three reps
• Plot size 15 M x 8 (0.09 m rows)
• Urea-N rates of 0, 80, 160, and 240 kg N/ha
• Single superphosphate rates of 0, 45, and 90 kg
P2O5/ha
Nutrient management
recommendations for
Uzbekistan
• Farmers are applying ~ 2 X the N and P
fertilizer needed for the yield levels.
• Fertilizer timing can probably be simplified.
Phosphorus can be applied just once, pre-
plant. Urea applications might be reduced
to two splits (pre-plant and squaring).
• Recommend N and P fertilizer rate trials.
Soil Fertility in
Afghanistan
• Soil pH ranges from
7.5-8.8 (Mean 8.2)
• CaCO3 ranges 3-42%
(Mean 23%)
• Phosphorus and deficiencies are widespread.
• 46 % soils < 10 ppm Olsen-P
• 66 % soils < 0.5 ppm DTPA-Zn
• Potassium is generally adequate
Fertilizer use
• Only on irrigated fields, mainly wheat
• Average of 152 kg diammonium phosphate
(18-46-0) (27 kg N/ha, 70 kg P2O5/ha)
• Average of 150 kg urea/ha (70 kg N/ha) in
two splits
• Infrequent response – reasons?
• Little manuring
Cereal production in Afghanistan, 1964-2003 (FAO, 2003)
Challenges for future of agriculture in
Afghanistan – Soil & Crop Mgt
• Cash crop replacement for opium poppy
• Research no-till wheat for dryland
• Inexpensive implements to band P fertilizer
• Access to Zn fertilizer
• Rebuild cotton gins for cotton production
• Training of agric. Scientists (undergraduate
and graduate level)
Soil Fertility in Africa
Production
per capita
and
Production
Area per
capita
• Soil P levels have probably decreased overall if
~5 kg P/ha is removed per year
•Expansion into more marginal lands
•Yield has decreased
•Fallow frequency and duration have decreased
•Other problems associated with land degradation,
e.g. soil crusting, wind and water erosion, etc.,
increase.
Agronomically, what has changed in
40-50 years?
Soil nutrient depletion
in Africa,
Smaling et al., 1997
Consumption, production, export, and import of mineral
fertilizer in Sub-Saharan Africa 1988-1999 (IFDC Website)
1988/89: 1,182,000 mt 1998/1999: 1,282,000 mt
Despite recognition of acute P and other nutrient deficiencies for ~ 50 y, no real
sign of progress in fertilizer consumption
Totals for
Sub-Saharan
Africa
1990-
1991
1991-
1992
1992-
1993
1993-
1994
1994-
1995
1995-
1996
1996-
1997
1997-
1998
1998-
1999
1999-
2000
2000-
2001
(x 1000 mt N + P2O5+K2O)
Consumption 1246 1267 1287 1341 1212 1073 1305 1252 1232 1303 1230
Production 547 543 573 539 376 348 327 272 314 296 167
Exports 207 190 179 171 134 110 95 117 157 103 83
Imports 1058 933 1096 1090 1026 827 1216 1162 1160 1146 1164
• Regional Phosphate Rock
• Partially acidulated PR
• Water soluble P fertilizers (SSP, TSP)
-- Regional SSP/TSP production
-- Import SSP/TSP/DAP
• Genetic Approach
• Agroforestry/VAM
Improving Crop Production under low
soil P fertility
Bationo,Christianson, and
Mokwunye, 1989.
Geologic Irony
Grain yields as affected by Kodjari phosphate rock
(PR) and TSP, Burkina Faso (Frederick et al., 1992)
Millet Sorghum Maize
Phosphorus Treatments
------------------------ kg/ha -------------------------
Control 596 916 2219
PR 698 (68) 1006 (39) 2464 (35)
PAPR 728 (88) 1103 (81) 2839 (88)
TSP 745 1146 2919
RAE (relative agronomic effectiveness are in parentheses)
Grain and seedcotton yields as affected by Tilemsi
phosphate rock (PR) and SSP, Mali, 1989-1992 (Bationo et al., 1997)
aP source rates in kg P/ha/yr are in parentheses
SSP Tilemsi PR
Sougoumba ------------- kg/ha ---------------
Sorghum 1.43 (11)a 1.52 (27)a
Cotton 1.42 (33) 1.39 (55)
Tinfounga
Maize 2.61 (22) 2.26 (27)
Cotton 1.61 (33) 1.41 (55)
Agroforestry
Faidherbia albida
African winterthorn/Mimosa –
VAM&Bradyrhizobium
0 5 10 15
DISTANCE (m)
0
10
20
30B
RA
Y I P
(m
g k
g-1
)
2050100
Soil depth
Soil available P as affected by
distance from Faidherbia albida
cm
Payne et al Crop
Sci. 38:1585-1591.
Needs for soil fertility
research/education/capacity
building
Research/extension education/capacity
building needs for improving soil fertility &
nutrient management
• India/South Asia – More balanced fertilization, more manure and residue
• Afghanistan – Cotton, hort crops, P, micronutrients
• Uzbekistan – more efficient irrig., rationalize N and P, i.e. less application/more for export
• Southeast Asia – improve NUE in rice w/LCCs, urea briquettes, green manures, P, animal manure
• West Africa – PAPR, N, lime, HYVs, animal waste
• Training of agric. Scientists (undergraduate, graduate/post-docs/visiting)