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)