Performance of Cowpea as a function of residues of organomineral fertilizers applied in corn crop

Organomineral fertilizers can be an excellent alternative through exploitation of the residues left by application in previous crops. Therefore, the objective of this study was to evaluate the agronomic characteristics of cowpea fertilized with residual organomineral fertilizers from the first corn crop in southern Maranhense. The experimental design was randomized blocks, arranged in a split-plot design, with three replications. Two cowpea cultivars (BRS Tucumaque and BRS Nova era) were sown in the plots. The residues of three phosphate fertilizers were sown in the subplot (two of which were organomineral fertilizers and one phosphate fertilizer (single superphosphate). At cowpea harvest, five plants were collected per plot for the following variables: number of nodes on the main stem at maturity, number of legumes per plant, number of grains per legume and weight of one thousand grains, and yield in kg ha-1. The cowpea cultivars are influenced by the cropping system (with and without U. ruziensis and organomineral sources). However, in soils with high phosphorus contents, the absence of U. ruziensis and fertilization or the use of organomineral or super simple fertilization promoted higher grain yields. The cultivar BRS Tucumaque had the highest grain yield. Organomineral and mineral fertilizer residues showed effective alternatives for increasing phosphorus availability in areas with Urochloa ruziziensis.