Resource information
There are more than 60 million
smallholder farmers in Sub-Saharan Africa (SSA). Declining
soil fertility is a fundamental impediment to agricultural
growth and a major reason for slow growth in food production
in SSA. In Africa, as a result of soil degradation,
irrigated lands may be, on average, 7 percent below their
potential productivity, rain-fed crop lands 14 percent below
their potential and rangelands 45 percent below potential.
Compared to parts of North America, Europe and of Asia, most
SSA soils are naturally not very fertile. Low in a number of
chemical constituents such as phosphorus, sulphur, magnesium
and zinc, low amounts of soil organic matter (SOM) combined
with poor land cover have resulted in poor soil structure,
limited rooting depth and susceptibility to accelerated
erosion. However, similar soils in other parts of the world
have been made highly productive by using appropriate
management techniques. There are two main approaches to
improved soil fertility management. One is to attempt to
meet plant requirements with purchased mineral fertilizers.
The second relies on biological processes to optimize
nutrient recycling, with little reliance on external
chemical fertilizers, but maximizing the efficiency of their
use. The more sustainable middle path borrows the best
features from both and is referred to as Integrated
Nutrition Management (INM). INM combines mineral fertilizers
with organic resources, thus increasing fertilizer use
efficiency, reducing the risks of acidification and
providing a more balanced supply of nutrients.
