Nodulation Productivity and Nutrient Uptake of Cowpea (Vigna unguiculata L. Walp) with Phosphorus and Potassium under Rainfed Conditions

Abstract

Low availability of phosphorus (P) and potassium (K) in acidic soil is a major constraint for crop production. Therefore, a field study was conducted to determine the effects of K and P on nodulation, productivity, and nutrient uptake of cowpea (Vigna unguiculata L. Walp) under rainfed conditions. The K and P were subjected to main and subplots, respectively with 100, 75, and 50% of fertilizer application. The growth and yield attributes were better using 100% K with 100% P. However, 100% K resulted in 20.9 and 16.9% greater green pod and stover yield than 50% K. Similarly, 100% P recorded 20.2 and 15.6% greater green pod and stover yield than 50% P. Uptake of nutrients such as nitrogen (N), P, and K followed the trend of greater to lower, 100% > 75% > 50%, in order for K and P. Similarly, nutrient-use efficiencies and production efficiency followed the trend of nutrient uptake.