Knowing the African Soils to Improve Fertilizer Recommendations

Abstract

Africa is the continent with the lowest fertilizer use per hectare ­notwithstanding the fact it possesses geologically old, infertile and degraded soils. This chapter discusses the agro-ecological zones (AEZ) and main soil types in Africa followed by a section on the extent, effects and costs of land degradation including issues of soil productivity and profitability associated with fertilizer use in Africa. There are a variety of soil types in the five major agro-ecological zones of Africa. Ferralsols and the Acrisol are dominant in the humid zones. Ferralsols are dominant in the sub-humid zone and so are Lixisols while in the semi-arid zone Lixisols have the larger share. Sixty five percent of the agricultural land in Africa is degraded and soil fertility depletion, a manifestation of soil degradation, is currently a serious threat to food security among small-holder farmers. Because of this state of affairs there is a strong case for enhanced fertilizer use. Maize yield has reportedly increased over the control due to NPK fertilizer application from various AEZ and when soils are amended with lime and manure yield response has been even higher. Indeed, there is credible evidence of fertilizer response and profitability in Africa relative to other parts of the world, particularly, for maize and rice thus making fertilizer investment worthwhile. In conclusion, there is need for agricultural intensification through efficient use of soil nutrient and water resources. Technologies need to be adapted to the specific bio-physical and socio-economics circumstances of the small scale farmers in Africa. There is also need to focus more on increasing the fertilizers use efficiency and the development of the local fertilizer sector in order to make them more profitable.