1. Agricultural risks linked to soil, water
and climate in Sub-Saharan Africa
Bationo A., Dougbedji F., Kapran
I.; Vlek P., Naab J., Zougmore R.,
Ouattara M., Tabo R., Mando A.,

2. Contents
 Introduction
 Risk: links to inherent low soil fertility and
low use of inputs
 Risk: links to water and climate
 Risk mitigation
 Conclusion

3. 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

4. Low Investment by Banks



5. yield in ton/ha
18
0
1
2
3
4
5
6
7
8
9
10
66
18
71
18
76
18
81
18
86
USA
18
91
18
96
19
01
19
06
19
11
19
16
19
SSA
21
19
26
19
31
19
36
19
41
19
46
19
51
19
56
19
61
L America 19
66
19
71
19
Growth in yields
76
19
81
19
86
19
91
19
96
China
20
01
Low in Africa due to inability of farmers to mitigate risks

6. Cereal production per capita in SSA
220
200
180
Productio (Kg)
160
140
y = -0.6484x + 176.83
R² = 0.3695
120
100
1961
1963
1965
1967
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
Source: FAOSTATS (2010)

7. Africa is spending 50 billion
dollars annually on food import
Africa Population (Billion)

8. Arable Land and Land in Permanent Crops Per Capita
0.48
0.44
0.39
0.35
0.30
77 78 79 80 81 82 83 84 85 86 87 88

9. The yield gap and limiting factors
Biophysical limitations
Potential - Soil fertility
yield - Water
(Experimentation)
- Germplasm
-etc
Which inputs are lacking?
Yield gap
Socio economic and policy
limitations
- Knowledge
- Credit Availability
- Input/output Market access
Actual - Policy, e.t.c
yield
Why inputs are not used?

10. The Yield Gap: Some observations from
sub-Saharan Africa
8
7
Zambia
6 Tanzania
Grain yield (t ha )
-1
5
4
3
2
1
0
On-farm On-station Commercial

11.  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%
12

14. Vent de sable

15. Macronutrient application versus
loss in Africa
5.0 4.4
Loss
4.5 Applied
Million tons per year
4.0
3.5 3.0
3.0
2.5
2.0
1.5
1.0 0.8
0.5
0.5 0.3 0.2
0.0
N P K
Nutrients

16. Per Hectare Fertilizer Use by Markets, 2002/03
(kg/ha)
Sub-Saharan Africa 8
Eurasia 20
Developing Markets Developed Markets
Africa 20
Oceania 59
Transitional Markets World
Central America 60
South Africa 61
North Africa 69
West Asia 72
Latin America 78
Eastern Europe 80
South America 84
World 93
North America 98
South Asia 102
Asia 146
Western Europe 175
East Asia 202

17. 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

18. Risk: Link to water and climate

19. Global Food Markets ̶ Food Supply
Climate vulnerability is already high and will
worsen with climate change
20 Rainfall variability & GDP growth 3.5
15 Zimbabwe 1979-1997 2.5
Rainfall variability (%)
GDP growth (%)
10 1.5
5 0.5
0 -0.5
-5 -1.5
-10 -2.5
1979 1982 1985 1988 1991 1994 1997
GDP growth (annual %) Rainfall
19

20. Burkina Faso: Relation between rainfall and cereal production
250 800
200
National rainfall index 600
Cereal production
Total cereal production - Variation from trend ('000 tons)
150
National rainfall index: Variation from trend (mm)
400
100
200
50
0 0
1960 1970 1980 1990 2000
-50
-200
-100
-400
-150
-600
-200
-250 -800
Years

21. Country Rainfall (R Potential R/PET (%) Average Annual
- mm) Evapotranspira Temperature
tion (PET - mm) (oC)
Niamey 580 2046 28 29
(Niger)
Lome 927 1243 75 28
(Togo)
Kumasi 2788 1216 229 26
(Ghana)
Paris 607 538 113 12
(France)
Sources:
(1). Agroclimatologie de l'Afrique de l'Ouest: Le Niger. M. V. K. Sivakumar et al. 1984. ICRISAT Buletin d'information N o 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

22. Low Water Storage Capacity of Most
African Soils
Soil A: Soil B:
3% Clay and 1% 33% Clay and 5%
Organic Matter Organic Matter
Typical soil of Sahel Good soil
 .ECEC (nutrient reserves):  ECEC (nutrient reserves):
1.0 15
 Low water storage  Five times more water
stored

23. Africa’s natural legacy: extreme rainfall variability
which reduces hydrological security
• Endemic droughts &
floods: 5%-25% GDP
losses
Risk of
recurrent • High temporal rainfall
drought variability and high spatial
soil nutrient heterogeneity

24. KENYA
Annual rainfall in Kenya 1956 –1982
Variability of 35-40% around the
mean
Floods 1997-1998 : $2.39
Droughts 1998-2000 : $2.41 billion billion infrastructure
losses (16% of GDP) damage

25. 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

26. Risk – mitigation and adaptation

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

28. 3000
Control
2500 Fert + Manure
Fertilizer
Grain yield (kg/ha)
2000
1500
1000
500
0
1960 1970 1980 1990
Sorghum grain yield as affected by
mineral and organic fertilizers over time.

29. Grain yield (GY) and water use
efficiency (WUE) for millet in Niger
Treatments SADORE DOSSO
GY WUE GY WUE
- Fertilizers 460 1.25 780 2.04
+Fertilizers 1570 4.14 1700 4.25
Improved soil fertility enhances the water
use efficiency of crops in the Sahel

30. Signs of Hope:
Rehabilitation, Prevention,

31. 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

32. Field multiplying of hybrid sorghum seeds

33. 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

34. 80% of World Reserves
Phosphate rock deposits in SSA