A major challenge is to find ways of making fertilizer available
to smallholders at affordable prices. There is also a need for ho-
listic approaches to soil fertility management that embraces the
full range of driving factors and consequences of soil degrada-
tion (TSBF-CIAT, 2006). This would include the integration of
mineral and organic sources of nutrients, thereby using locally
available sources of inputs and maximizing their use efficiency.
RESOURCES FOR IRRIGATION
about 9 kg/ha of arable land, compared to a world average of Irrigated land area increased rapidly until 1980 with expansion
101 kg/ha (Camara and Heinemaan, 2006; FAOSTAT 2009). rates of more than 2% a year. In Asia in particular, it led to a
Within Africa, there are strong differences in fertilizer use steady increase of staple food production together with other
between regions, with relatively high use in Northern and elements of the green revolution package (Faures et al., 2007).
Southern Africa, and very low use (around 1 to 2 kg/ha) in After 1980, growth in expansion of irrigated area decreased
Western and Central Africa. Taking the increase as proposed and it is assumed this trend will continue in the near future.
by the Africa Fertilizer Summit as a starting point, this would One of the reasons is that the areas most suitable for irrigation
mean a growth of the yearly use of fertilizers from 1 to 6 mil- are already used, leading to higher construction costs in new
lion tonnes. Based on the price of fertilizer (DAP) of approxi- areas (Faures et al., 2007). Another reason is the strong decline
mately US$600/tonne (beginning of 2008), this would mean in relative food prices over the last decades, which makes it less
US$3 billion/year for the purchase of DAP only. A more mod- profitable to invest in irrigation. Current irrigation systems
erate price of US$200/tonne would still mean US$1 billion/ could be improved by investing in water control and delivery,
year. Added to this are significant costs of and investments in automation, monitoring and staff training.
transport and distribution, developing agricultural research,
extension programs, capacity building, etc. Indeed, there are The irrigated area has remained very low in Sub-Saharan Af-
many reasons for this low use. One of the reasons is the high rica and of the land under irrigation, 18% is not used (FAO,
retail prices of fertilizers, especially in areas with poor infra- 2005b). In most African regions the major challenge is not
structure. A metric tonne of urea costs $90 in Europe, $120 the lack of water, but unpredictable and highly variable rainfall
kg in the harbor of Mombassa, $400 in Western Kenya and patterns with occurrences of dry spells every two years caus-
$770 in Malawi (Sanchez, 2002). ing crop failure. This high uncertainty and variability drive
the risk-averse behaviour of smallholder farmers. Rarely are
A major challenge is to find ways of making fertilizer available investments made in soil management and fertility, crop vari-
to smallholders at affordable prices. There is also a need for eties, tillage practices and even labour in order to avoid losses
holistic approaches to soil fertility management that embraces in case of total crop failure (Rockstrom et al., 2007a,b). Man-
the full range of driving factors and consequences of soil degra- aging the extreme rainfall variability over time and space can
dation (TSBF-CIAT, 2006). This would include the integration provide supplemental irrigation water to overcome dry periods
of mineral and organic sources of nutrients, thereby using lo- and prevent crop failure. In combination with improved soil
cally available sources of inputs and maximizing their use effi- management (in regions with severe land degradation, only
ciency, while reducing dependency upon prices of commercial 5% of the rainwater is used for crops), this should reduce the
fertilizers and pesticides. The use of perennials, intercropping risk of total crop failure and enhance the profitability of invest-
and agroforestry systems, such as the use of nitrogen fixating ments in crop management, for example, fertilizers, labour
leguminous trees, are ways to increase nutrient availability, but and crop varieties. Increasing crop canopy coverage reduces
also enhance water availability and pest control, in a more sus- evapo-transpiration from the soil, improving soil moisture and
tainable manner (Sanchez, 2002). the provision of water for the crop.
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