Optimum time for phosphorus fertilization on Egyptian alluvial soil

Abstract

The rapid fixation of phosphorus fertilizers in soil with a high content of calcium carbonate requires efficient management methods for phosphorus fertilization, especially as regards the time of application. For this purpose, a field experiment was carried out in the summer season of 2006/2007 in the experimental farm of the Soils Department, Faculty of Agriculture, Mansoura University, Egypt to evaluate the best time for phosphorus fertilization to cowpea on Egyptian alluvial soil. The results showed that adding half the recommended phosphorus fertilization rate at sowing and the other half before the first irrigation was the best treatment to enhance phosphorus fertilizer use efficiency, contributing to an increased uptake of phosphorus by cowpea, reflected in the higher phosphorus concentration in the grains. Increased phosphorus uptake also caused an increase in the nitrogen and potassium concentrations in cowpea grains, whereas the zinc and iron concentrations decreased.