Department of Plant Sciences

African soils have an inherently poor fertility because they are very old and lack volcanic rejuvenation. Inappropriate land use, poor management and lack of input have led to a decline in productivity, soil erosion, salinization and loss of vegetation. Africa is burdened with a US$ 9.3 billion annual cost of desertification. An estimated of US$ 42 billion in income and 6 billion ha of productive land are lost every year due to land degradation and declining agricultural productivity. African soil mining balances are often negative indicating that farmers mine their soils and about $ 4 billion per year is lost due to nutrient mining. Soil moisture is perhaps the overriding constraints to food production in much of Africa and only 14% of Africa is relatively free of moisture stress.

The extent of such losses is of sufficient importance that steps such as recapitalization of soil fertility, increased use of inorganic fertilizer, and more efficient recycling of biomass within the farming system are being taken. As a result of the above problems, scientists have concluded that soil-fertility depletion in smallholder farms is the fundamental biophysical root cause of declining per capita food production in Africa, and soil fertility replenishment should be considered as an investment in natural resource capital.