Agro-Economic Returns from Rice + Cowpea Intercropping Under Varying Nitrogen Rates

Abstract

Field experiments were conducted in the cropping seasons of 2009 and 2010 at the Teaching and Research Farm of the Delta State University, Abraka (latitude 5⁰ 46’ and longitude 6⁰ 5’) in the wet humid rainforest of Southern Nigeria. The main aim of the experiment was to evaluate the agro-economic returns obtainable from the intercrop involving rice (Oryza sativa L.) and cowpea (Vigna unguiculata L. Walp) at varying levels of nitrogen fertilizer (0, 15, 30 and 45 kgNha^-1). The mean yield of rice grown under sole cropping was higher than that intercropped with cowpea. Maximum rice grain yield of 2340.82 kg ha^-1 and 1960.59 kg ha^-1 in sole and intercrop respectively, were achieved with 45 kgNha^{- 1}. Rice-cowpea intercrops with 30 kgNha^{- 1} gave the highest net returns of $628.72, high benefit/cost ratio, land equivalent ratio and monetary advantage index. From this study, it is inferred that intercropping of rice with cowpea at 30 kgNha^{- 1} is most likely to give higher income, increased use efficiency and thus enhancing sustainability of crop production than sole cropping of each crop species. Hence it is recommended for farmers to intercrop rice and cowpea and apply nitrogen at 30 kgNha^{- 1} in other to achieve optimum economic crop yield in upland rice based ecosystems.

Keywords Monetary advantage index, benefit/cost ratio, rice, cowpea, nitrogen fertilizer