Causes, consequences and control of wind erosion in Sahelian Africa: A review

Sahelian Africa is one of the poorest regions of the world, where approximately 90 per cent of the population depends on subsistence agriculture. Due to the high population growth, with annual growth rates of about 3 per cent during recent decades, farmers have expanded their cropping areas to increase production. At the same time the traditional bush fallow system collapsed and more land became subject to soil degradation processes. Wind erosion is one of the main degradation processes that has received much scientific attention since the 1980s. The objective of this paper is to review the latest research results on wind-erosion causes, consequences, perceptions and control in the Sahel. First the main processes involved in wind erosion (creep, saltation and suspension) are described and related to the Sahelian climate, soils and farming systems. Then the agricultural consequences of wind erosion are evaluated. Three types of damage are distinguished: undesired sedimentation, crop damage and soil degradation. Several studies were done to determine farmers knowledge and perceptions of wind erosion. In general the Sahelian farmers have a good qualitative understanding of wind-erosion processes, and they are concerned about the consequences, especially about crop damage and soil productivity decline. Finally, the possibilities and constraints for wind-erosion control are evaluated. The most widely applied control measure is mulching with crop residues, but the quantity of residue is insufficient due to low biomass yields and multiple uses. It is concluded that regeneration and exploitation of natural, scattered vegetation is a promising control strategy that needs more research. Copyright (C) 2002 John Wiley Sons, Ltd.