Nitrogen fertilizer management strategy for oil palm-maize intercropping system in the semi-deciduous forest zone of Ghana

  In an attempt to increase yield of maize in oil palm-maize intercropping system, farmers resort to indiscriminate cutting of fronds of palms leading to low yield of oil palm. This study evaluated the impact of different N fertilizer levels on maize varieties in oil palm-maize intercropping system. The economics of nitrogen application was also studied. The treatments were: T1-Sole oil palm, T2-Oil palm+‘Omankwa’, T3-Oil palm+‘Abelehi’ and T4-Oil palm+ ‘Obatanpa’. The crop associations were superimposed with nitrogen fertilizer levels as sub-treatments at N0- N0:P0:K0, N1-N60:P60:K60, and N2-N120:P60:K60 per ha. The experiment was a split plot design with 4 replications. There was no significant difference (p< 0.05) between maize varieties across seasons for both maize yield and aboveground biomass though ‘Omankwa’ was promising across seasons and more responsive to nitrogen application. Across the three maize varieties, N60P60K60 was significantly higher (p<0.05) by 40% and 17% for maize yield and aboveground biomass respectively as compared to N0:P0:K0. The study recommends N60P60P60 fertilizer level and further states that to improve fertilizer adoption, government should subsidize fertilizer cost for farmers to purchase. The outcome of cost benefit analysis revealed that return per cash invested favored cropping system with N60:P60:K60 and season with less water stress