Relationship between extracted phosphorus and sorghum yield in a Vertisol and an Alfisol under rainfed cropping

andhra pradesh crop yield cultivo de temporal culture pluviale disponibilidad de nutrientes fertilidad del suelo fosforo luvisol luvisoles luvisols nutrient availability phosphore phosphorus rainfed farming rendement des cultures rendimiento de cultivos soil fertility sorghum bicolor vertisol vertisoles vertisols