The role of termites and mulch in the rehabilitation of crusted Sahelian soils

During recent decades Sahelian soils have gone through various forms of degradation, the most spectacular one being the extension of bare and crusted soils. Mulch, when placed on a crusted and bare soil, triggers termite activity within a few months. Many burrows are opened through the sealed surface of the soil due to the borrowing activity of the termites. Throughout the soil profile, macropores with irregular shapes and with different diameter sizes are created. As a result of changes in soil structure, other soil physical properties are also improved. Soil resistance to cone penetration is reduced from a critical to a suitable level for vegetation growth. Bulk density is decreased and soil hydraulic conductivity is greatly increased. Water infiltration and drainage are also greatly improved. The combination of the increase of porosity and infiltration and the cover effect of mulch results in an increase of soil water availability in the soil profile during the growing season. Termite activity enhances decomposition of the mulch and hence nutrient release in the soil. The change of soil characteristics due to termite activity was enough to create conditions necessary for natural vegetation development and crop production on previously degraded bare soils in the Sahelo-Soudanian zone of northern Burkina Faso.