The impact of termites and mulch on the water balance of crusted Sahelian soil

The effects of termite activity and four mulch types on the water balance of crusted soil were studied on two soils (a lixisol and a cambisol) in northern Burkina Faso. A split plot design with three replications was used, with termite and non-termite as main factor and mulch treatments as second factor with three variables consisting of Pennisetum pedicellatum mulch (straw), woody material of Pterocarpus lucens mulch (woody material) and composite mulch (straw + woody material) applied at rates of 3, 6 and 4 t ha⁻¹, respectively. Dieldrin kept termites away from the non-termite plots during the experiment. Water balance terms were assessed during three rainy seasons (1993, 1994 and 1995). Termite activity resulted in a statistically significant increase of water infiltration, soil water storage and drainage. In 1993 the mean values for soil storage were higher (but not statistically significant) on mulched plots than on bare plots. During 1994 and 1995 the three mulch treatments formed a distinctive group that differed from bare treatments. Mulch treatment did not affect evapotranspiration and draimage in the two dry/normal years (1993 and 1995). Termite activity in mulch resulted in a statistically significant improvement in the humidification and water conservation of the crusted soil. Mulch without termites did not have a statistically significant effect on the water status of structurally crusted soil. This suggests that termite activity is a key element in the effectiveness of the mulching technique on crusted soil in the Sahel.