Effect of termites and mulch on the physical rehabilitation of structurally crusted soils in the Sahel

Abstract

The effectiveness of mulch and termite activity in the rehabilitation of the physical properties of crusted soil was studied in northern Burkina Faso (Province de Bam). A split plot design was used with three replications each being on one soil type. The soil types were Ferric Lixisol, Haplic Lixisol and Chromic Cambisol. The main factor was termite activity, and to this end dieldrin (0.50 kg a.i. ha(-1)) was used to create plots without termite activity next to plots with termite activity. The subplots consisted of Pennisetum pedicellatum mulch, wood Pterocarpus lucens mulch and composite (wood + straw) mulch, applied at rates of 3, 6 and 4 t ha(-1), respectively. Two years after establishing the experiment, the combined effect of termite and mulch on the change in physical properties of the soil was measured. The parameters used for this assessment were porosity, saturated hydraulic conductivity and soil resistance to cone penetration. Soil water content was also measured. Termite activity was found to increase soil porosity, soil saturated hydraulic conductivity, improve soil water status and reduce soil bulk density and soil resistance to cone penetration. The only difference between bare plots and mulched plots without termites was in water content. This indicates that the mechanism whereby mulch improves the physical properties of crusted soil is mainly based on soil biology processes and to a limited extent on protecting soil against weather impact. (C) 1997 John Wiley & Sons, Ltd