Soil quality improvement for crop production in semi-arid West Africa

Soil quality maintenance and crop production improvement in semi-arid West Africa require appropriate cropping technologies, which are ecologically sound and economically viable. Thus, on-farm and on-station experiments have been carried out on the central plateau and in the south of Burkina Faso The results show that adoption of improved soil fertility technologies such as composting by farmers is determined by soil fertility status, access to the market and social reasons. Organic amendments increase crop production but its effects on soil carbon depend on its quality. Soil tillage improves crop performance as a result of enhanced crop nutrient uptake and water use efficiency but decrease soil carbon with fertilisation. Combination of crop residues and urea may reverse this negative effect. Soil fauna accounted for 50 % of crop production. Termites mediated the disappearance of low-quality organic amendments. Soil carbon build-up in the presence of soil fauna requires the use of easily decomposable organic material or combined low quality organic material with nitrogen fertiliser. Phosphate rock-derived phosphorus availability is 4 times higher in earthworm casts than in surrounding soil. Single use of nitrogen fertiliser leads to low use efficiency by crop and induces low to negative economic benefit. Combination of organic resource and fertiliser significantly increases crop performance and economic benefit of N fertilisers. Without both organic and mineral external inputs, soil quality maintenance and crop production improvement cannot be achieved at the same time in semi-arid West-Africa. Improving soil quality and crop performance in semi-arid West-Africa is best achieved with an integrated soil fertility management including external inputs (organic and mineral), the contribution of soil fauna and soil and water conservation measures and in some cases with tillage