Contribution of previous legumes to soil fertility and millet yields in West African Sahel
Studies on combined effects of 4 legume crops residues and rock phosphate application on pearl millet yield were undertaken on sandy acid soil field from 2012 to 2015 at ICRISAT Sahelian center (ISC)- Sadore, Niger. The objective of the experiment was to assess the best combination of legume species x rate of crop residue x rock phosphate doses that can sustainably improve pearl millet yield in cereal monoculture system with a low input cost and minimum soil tillage. Over 3 years, the residual effect of previous legume crop residue significantly improved not only the grain yield (P<0.001) and dry residue yields (P<0.001) but also the growth parameters of pearl millet than millet mono-cropping. Treatments with or without natural rock phosphate did not show any statistical differences on millet yield while adding a micro dose of urea improved significantly the yield (P<0.001). The interaction effects of preceding legume crops in rotation with millet and restitution of dry residue on the earlier mentioned parameters across 3 years mono-cropping were studied in this experiment.