United Nations Food and Agriculture Organization United Nations

Termites are the most important soil fauna in the Sahelian zone of Africa, intensely interacting with the soil. Both the biotic and abiotic state of the soil affect the termite population and activity. The construction by termites of nests, gallery systems or sheetings from soil or from a mixture of soil and other material within the soil horizons or on the soil surface affect the physical and chemical status of both the material used for the construction and the surrounding soil from which the materials were taken. In fact, structure, structure stability, porosity, chemical status of the soil and the decomposition of organic residues are to a large extent altered by termite activity. This presentation focuses on the contribution of termite activity triggered by the use of various types of mulch to the rehabilitation of crusted soils in the SaheloSoudanian zone. It appeared that mulch, when placed on a crusted and bare soil, can trigger termite activity within a few months. Termite activity results in a change in soil structure. Many burrows are opened through the sealed surface of the soil due to the burrowing activity of the termites. Throughout the soil profile, macropores with irregular shapes and with different diameter sizes are created. The aggregation of the soil by termites through their building systems is also observed. 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 enhanced the decomposition of the mulch and hence nutrient release in the soil. The crown was the spectacular response of both the natural vegetation and a cowpea crop which both showed an increase from virtually nothing to a lush vegetation. This was indicated in the natural vegetation by a highly significantly increased percentage of cover, aboveground biomass, number of native plant species and rainfall use efficiency. It was concluded that termite activity can create conditions necessary for natural vegetation and crop growth and therefore, termite in the Sahel could change from being an enemy to a friend.