Bationo A., Dougbedji F., Kapran

I.; Vlek P., Naab J., Zougmore R.,

Ouattara M., Tabo R., Mando A.,

Agricultural risks linked to soil, water

and climate in Sub-Saharan Africa

Contents

Introduction

Risk: links to inherent low soil fertility and low use of inputs

Risk: links to water and climate

Risk mitigation

Conclusion

The Gloomy Picture

Number of Africans living below the poverty line

(<USD 1/day) has increased by 50% over the

past 15 years

200 million people - over one-third of the

population - suffers from hunger

The number of undernourished children has

increased by 12% over the last 5 years

3

Low Investment by Banks

Growth in yields

0

1

2

3

4

5

6

7

8

9

10

1866

1871

1876

1881

1886

1891

1896

1901

1906

1911

1916

1921

1926

1931

1936

1941

1946

1951

1956

1961

1966

1971

1976

1981

1986

1991

1996

2001

yiel

d in

ton

/ha

USA SSA L America China

Low in Africa due to inability of farmers to mitigate risks

Cereal production per capita in SSA

Source: FAOSTATS (2010)

y = -0.6484x + 176.83 R² = 0.3695

100

120

140

160

180

200

220

196

1

196

3

196

5

196

7

196

9

197

1

197

3

197

5

197

7

197

9

198

1

198

3

198

5

198

7

198

9

199

1

199

3

199

5

199

7

199

9

200

1

200

3

200

5

200

7

Pro

du

cti

o (

Kg

)

Africa is spending 50 billion

dollars annually on food import

Afr

ica P

opula

tion (

Bill

ion)

0.30

0.35

0.39

0.44

0.48

77 78 79 80 81 82 83 84 85 86 87 88

Arable Land and Land in Permanent Crops Per Capita

The yield gap and limiting factors

Potential yield

(Experimentation)

Actual yield

Yield gap

Biophysical limitations - Soil fertility - Water - Germplasm -etc Which inputs are lacking?

Socio economic and policy limitations - Knowledge

- Credit Availability - Input/output Market access - Policy, e.t.c Why inputs are not used?

The Yield Gap: Some observations from sub-Saharan Africa

0

1

2

3

4

5

6

7

8

On-farm On-station Commercial

Gra

in y

ield

(t

ha

-1 )

Zambia Tanzania

Risk: link to inherent low

soil fertility and low use of

fertilizers

12

Land degradation

Africa loses equivalent of $4b per year due to soil nutrient mining

An estimated $42b in income are lost and 6 million hectares of productive land threatened every year due to land degradation

Despite about U$ 20b of commercial imports and U$ 2b of food aid, 26% of the people are undernourished

Unsustainable soils for crop production occupy 55%, prime 9.6%, high potential 6.7% and medium and low potential 28.3%

Vent de sable

Macronutrient application versus loss in Africa

4.4

0.5

3.0

0.8

0.3 0.2

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

N P KNutrients

Mil

lion

ton

s p

er y

ear

Loss

Applied

202

175

146

102

98

93

84

80

78

72

69

61

60

59

20

20

8Sub-Saharan Africa

Eurasia

Africa

Oceania

Central America

South Africa

North Africa

West Asia

Latin America

Eastern Europe

South America

World

North America

South Asia

Asia

Western Europe

East Asia

Per Hectare Fertilizer Use by Markets, 2002/03

(kg/ha)

Developing Markets Developed Markets

Transitional Markets World

Depleted soils reduce payoffs on

agricultural investments and ecosystem services

• Efficiency of fertilizer and water inputs is reduced

• Profitability and returns on labour are reduced

• Vegetative cover is reduced

• Water quality is reduced

• Natural habitats are encroached upon

• Above and below ground biodiversity is reduced

• Carbon storage is reduced

Risk: Link to water and climate

19

-10

-5

0

5

10

15

20

1979 1982 1985 1988 1991 1994 1997

GD

P g

row

th (

%)

-2.5

-1.5

-0.5

0.5

1.5

2.5

3.5

Rain

fall v

ari

abilit

y (

%)

GDP growth (annual %) Rainfall

Climate vulnerability is already high and will

worsen with climate change

Rainfall variability & GDP growth

Zimbabwe 1979-1997

Global Food Markets ̶ Food Supply

-250

-200

-150

-100

-50

0

50

100

150

200

250

1960 1970 1980 1990 2000

Years

Nati

on

al

rain

fall

in

dex:

Vari

ati

on

fro

m t

ren

d (

mm

)

-800

-600

-400

-200

0

200

400

600

800

To

tal

cere

al

pro

du

cti

on

- V

ari

ati

on

fro

m t

ren

d (

'000 t

on

s)

National rainfall index

Cereal production

Burkina Faso: Relation between rainfall and cereal production

Country Rainfall (R

- mm)

Potential

Evapotranspira

tion (PET - mm)

R/PET (%) Average Annual

Temperature

(oC)

Niamey

(Niger)

580 2046 28 29

Lome

(Togo)

927 1243 75 28

Kumasi

(Ghana)

2788 1216 229 26

Paris

(France)

607 538 113 12

Sources:

(1). Agroclimatologie de l'Afrique de l'Ouest: Le Niger. M. V. K. Sivakumar et al. 1984. ICRISAT Buletin d'information No 19

(2). Analyse pluviometrique du Togo pour une planification a long term

(3). Cartograhie de l'evapotransporation potentiel: son utilisation pour la determination des besoin en eau d'irrigation. A. Darlot et C. Lecharpentier

Good soil

ECEC (nutrient reserves): 15

Five times more water stored

Typical soil of Sahel

.ECEC (nutrient reserves): 1.0

Low water storage

Soil B: 33% Clay and 5%

Organic Matter

Soil A: 3% Clay and 1% Organic Matter

Low Water Storage Capacity of Most African Soils

Risk of recurrent drought

• Endemic droughts & floods: 5%-25% GDP losses

• High temporal rainfall

variability and high spatial soil nutrient heterogeneity

Africa’s natural legacy: extreme rainfall variability which reduces hydrological security

KENYA

Floods 1997-1998 : $2.39 billion infrastructure damage

Droughts 1998-2000 : $2.41 billion losses (16% of GDP)

Annual rainfall in Kenya 1956 –1982 Variability of 35-40% around the

mean

IPCC PROJECTIONS FOR AFRICA

CO2 enrichment

Temperature rise of 1.5 to 4 ⁰C this century

Fewer colder days and nights

Frequent hot days and nights

Arid areas will get drier, humid areas wetter

Increase in droughts and floods

Sea-level rise

Major desertification and soil salinization in

some countries

Risk – mitigation and adaptation

Conclusion

Our dream is to have a continent where children do not go to bed on empty stomachs

0

500

1000

1500

2000

2500

3000

1960 1970 1980 1990

Grain

yield

(kg/h

a)Control

Fert + Manure

Fertilizer

Sorghum grain yield as affected by

mineral and organic fertilizers over time.

Grain yield (GY) and water use efficiency (WUE) for millet in Niger

Improved soil fertility enhances the water use efficiency of crops in the Sahel

4.25 1700 4.14 1570 +Fertilizers

2.04 780 1.25 460 - Fertilizers

WUE GY WUE GY

DOSSO SADORE Treatments

Signs of Hope:

Rehabilitation, Prevention,

Water-nutrient interactions: Zai example

Technology Sorghum yield (kg/ha)

Only planting pits

200

Pit + cow dung

700

Pit + Mineral fertilizers

1400

Pit + Dung and fertilizers

1700

Field multiplying of hybrid sorghum seeds

P fertilizer use:

- SSA: 1.6 kg P/ha

- Latin America: 7.9 kg P/ha

- Asia: 14.9 kg P/ha

About 80% of SSA soils are short of P

Phosphate rock deposits in SSA

80% of World Reserves