Wind erosion in the Sahelian zone of Niger : processes, models, and control techniques

In the Sahelian zone of Niger, severe wind erosion occurs mainly in the first half of the rainy season (May - July), when violent winds preceding thunderstorms result in intense sediment transport. Quantification of this wind erosion is difficult due to a high degree of temporal and spatial variability in wind-blown particle mass fluxes. Using improved techniques to collect field data in Niger and developed models revealed that a single wind erosion event may result in severe losses of soil particles and nutrients from unprotected fields. The many technical measures available to reduce wind erosion do not always fit into the Sahelian farming systems. A survey revealed that mulching with crop residues is the main control technique applied by Nigerien farmers, but the quantity of crop residues available for soil conservation is limited, as stover has also other important uses. Field tests with flat pearl millet stalks showed that small quantities can significantly reduce sediment transport during moderate storms. However, sediment transport may actually be intensified by small quantities of mulch during severe storms, because of increased turbulence around the stalks.