EFFECTS OF PHOSPHORUS FERTILIZER AND VARIETAL DIFFERENCE ON COWPEA (VIGNA UNGUICULATA (L.) WALP.) GROWTH, NUTRIENT UPTAKE, AND SOIL CHEMICAL PROPERTIES

Abstract

The study evaluated the influence of varietal difference and phosphorus (P) fertilizer rates on cowpea growth, nutrient uptake and soil chemical properties. Three kilogramme of an Ultisol was sampled from 0–15 cm depth at the Teaching and Research Farm of the Obafemi Awolowo University, Ile-Ife, and amended with single super phosphate at the rates of 0 (SP0), 20 (SP1), 40 (SP2) and 60 (SP3) kg P ha^-1, respectively. The soil was maintained at two seedlings of cowpea per pot for two consecutive 8-week planting periods. After each cropping, agronomic parameters (plant heights (PLHT), number of branches (NOB), number of leaves per plant (NOLF), dry matter yield (DMY), plant tissue nutrients (N, P, K, Ca, Mg), and soil chemical properties (pH, soil organic matter, available P, exchangeable cations) were determined. Results showed that soil exchangeable cations were statistically similar among phosphorus rates. produced similar effects on Increases in agronomic parameters such as PLHT, NOB and NOLF were obtained with SP1, SP2 and SP3 over the control. While the tissue contents of N, Ca, and K were similar among the fertilizer treatments, the tissue contents of P and Mg were significantly increased by SP2 at the second planting. The DMY and shoot uptake of N, P, Mg and Ca were increased (p<0.05) by the variety TVX 113 and fertilizer treatment SP2. Considering the superior performances of cowpea variety TVX 113 and phosphorus application rate of 40 kg P ha^-1 on most measured plant agronomic traits and soil properties, they are recommended for enhanced cowpea production.