Soil macrofauna affect crop nitrogen and water use efficiencies in semi-arid West Africa.

It is increasingly recognised that soil fauna have a significant role in soil processes affecting nutrient availability and crop performance. A field experiment was conducted in southern Burkina Faso (West Africa) to investigate the contribution of soil fauna to nutrient availability and crop performance after application of different organic materials with contrasting qualities. A split plot design with four replications was laid out. The main treatment was the use of insecticides, to establish plots without fauna next to plots with fauna. The sub-treatments consisted in the application of Andropogon straw, cattle dung, maize straw, compost or sheep dung and a control. Soil fauna significantly increased crop water use efficiency. Crop nutrient use efficiency was high with the use of easily decomposable organic material in the presence of soil fauna. Supplementing low quality organic resources with mineral nitrogen is required to optimise the effects of their interaction with soil fauna towards enhanced crop nutrient and water use efficiencies.