Cowpea Stover Yield, Seed Mass and Soil pH under Different Management Practices and Environmental Conditions

Abstract

Background and Objective: Cowpea production is affected by crop rotation and this indicates the N contribution in cereal-legume rotation. The study was conducted to investigate the effect of cropping system, location, planting season and nitrogen fertilization on cowpea stover yield, seed mass and soil pH. Materials and Methods: The study comprised of three cropping systems (Maize-cowpea rotation, monocropping cowpea and intercropped cowpea), three locations (Potchefstroom, Taung and Rustenburg) and two rates of nitrogen fertilizers applied in kg ha-1 at each site (0 and 20 at Potchefstroom, 0 and 17 at Rustenburg, 0 and 23 at Taung). A factorial experiment randomized in complete block design with three replications was conducted during 2011/12 and 2012/13 planting seasons. The measured parameters were plant population at harvest, stover yield, seed mass and soil pH (KCl). Results: Cowpea harvested at Potchefstroom and Taung had significantly higher stover yield of 1319.4 and 1784.9 kg ha-1, respectively than cowpea harvested at Rustenburg. Seeds harvested from intercropped system had significantly higher mass of 15.35 g than seeds harvested from mono-cropped and rotational systems. The interactions of location and planting season had significant effect on plant population and stover yield during harvesting. Soil collected at Taung had pH of 6.47 (slightly acidic) compared to soil collected at Potchefstroom and Rustenburg. Conclusion: Application of nitrogen fertilizer has no influence on the production of cowpea. Location with higher percentage of clay experienced reduction in soil pH.