PHOSPHORUS FERTILIZATION AND CROPPING SYSTEM EFFECTS ON BIOMASS AND NUTRIENT DYNAMICS IN MAIZE–COWPEA INTERCROPPING

Abstract

Maize–cowpea intercropping has been widely advocated as a strategy to enhance resource-use efficiency in low input systems, but the magnitude of the effect of phosphorus supply on biomass production and nutrient partitioning is context dependent. Four rates of P (0, 50, 100 and 150 kg P ha⁻¹) and three cropping systems (sole maize, sole cowpea, and intercropping maize with cowpea in a split plot randomized complete block design with three replications) were used in this study. Most of the effects of phosphorus application were minimal for stover dry matter and for most macro and micron nutrient concentrations while cropping system significantly affected biomass production and tissue nutrient composition. Maize generally did not accumulate as high concentrations of several macronutrients as did intercropped cowpea which produced the highest dry matter. Phosphorus concentration increased gradually with increasing P rate in cowpea seed, and peaked at 150 kg P ha⁻¹; the same was true for Mg that responded significantly to fertilization. The sole cropped cowpea seeds had higher P, K, Ca and Mg concentrations compared to intercropped seeds while Cu concentration in intercropped seeds was higher than that of sole cropping. Positive correlations between seed P and Mg, K and Ca and negative correlation between seed P and Fe, Cu and Mo were found by the correlation analysis. In general, cropping arrangement had more impact than phosphorus rate on biomass production and nutrition, which further emphasizes the need to consider the crop configuration along with the phosphorus rate in low-fertility environments.