Growth and Yield Responses of Pigeonpea to Variable Phosphorus Application Rates When Intercropped With Maize under Dryland Conditions

An Agronomic field study was conducted at University of Limpopo Experimental farm, Syferkuil, over two summer growing seasons to determine the optimum phosphorus (P) rate and also assess the productivity of pigeonpea under intercrop with maize. Five P rates (0, 15, 30, 45, and 60 kg P ha-1) were evaluated under sole and intercropped pigeonpea. Treatments were laid out in a randomized complete block design with four replicates. Results revealed that variable P fertilizer rates exerted significant effect on pigeonpea grain yield in both seasons. Highest grain yields of 922 and 1141.7 kg ha-1 under sole and intercrop plots, respectively, were achieved at 45 kg P ha-1 during first and second seasons, respectively. However, the predicted optimum grain yield of 734 and 1034 kg ha-1 based on the response model was achieved at 52.67 kg P ha-1 and 42.84 kg P ha-1, in the respective seasons. Intercropping achieved a significantly higher pigeonpea grain yield (+37%) during second year than sole cropping following P addition; with over 21% mean grain yield advantage across the two planting seasons. Hence, depending on the inherent soil-P level, application of 42-53 kg P ha-1 under pigeonpea/maize intercrop represents the range at which P is optimum for maximum pigeonpea grain yield and better returns for farmers.