Effects of phosphorus on yield of cowpea cultivars intercropped with pearl millet on Psammentic paleustalf in Niger

Phosphorus (P) is the most limiting soil nutrient in the sandy soils of Niger and farmers rarely use chemical fertilizers in producing pearl millet and cowpea. A 3-yr study was conducted in farmer's fields at two locations in South Western Niger to investigate yield response of six cowpea cultivars to applied P-fertilizer (0, 8, 16 kg ha^–1) when intercropped with millet. Significant yield differences were found between cultivars for their seed and dry fodder yield at all rates of applied P. Cultivars responded differently to the application of P. Millet grain was more than doubled with the addition of 8 to 16 kg P ha^–1. Cowpea cultivars did not have significant differential effect on millet yields. Cowpea cultivars differed significantly in the accumulation of P in fodder with the highest yielding cultivars taking up more P than the low yielding ones. The results have important implications for breeding and selection of cowpea cultivars that are adapted to a range of fertility levels.Submitted as Journal Article No. 1211 of ICRISAT.