Soil macrofaunal-mediated organic resource disappearance in semi-arid West Africa

A field experiment to investigate the interaction of soil fauna and organic resource quality in the applied organic material mass loss was conducted on a Eutric Cambisol in southern Burkina Faso during the 2000 rainy season. Plots were treated with the pesticides Dursban and Endosulfan or left untreated (main treatments). Sub-treatments consisted of surface-placed maize straw, Andropogon straw or cattle dung. Organic materials were applied at a rate equivalent to the application of 40 kg N ha(-1). Litterbags and direct estimation methods were used to follow the litter mass loss of the different organic materials. Without soil macrofauna, 96% of Andropogon straw, 70% of cattle dung and 34% of maize straw were not broken down 3 months after application, whereas in the presence of soil fauna only 19% of Andropogon straw, 8% of cattle dung and 5% of maize straw remained 3 months after application. Soil depth (surface-placed or buried) had little or no influence on organic resource disappearance in the absence of soil fauna. The interaction between organic resource quality and soil macrofauna had a large influence on the timing of organic material disappearance. Termite density was strongly correlated with the remaining organic material, with organic material being preferred over easily decomposable organic resources. In semi-arid low-input agricultural systems, soil fauna (termites) determine the rate of decomposition of organic resources. (C) 2004 Elsevier B.V. All rights reserved.