Abstract

 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.
Highlights
The oil palm industry in Ghana has developed over the last three decades into a huge and important industry and is considered as the important cash crop to Cocoa in Ghana
We argue that in the case of Ghana, Policy Makers have tended to overlook the importance of maize cultivars in adapting to low soil fertility and climate variability/change
Our analysis suggests that the changes in precipitation patterns between the two seasons influenced maize yield to a greater extent
Summary
The oil palm industry in Ghana has developed over the last three decades into a huge and important industry and is considered as the important cash crop to Cocoa in Ghana. According to Osei-Amponsah et al (2018), oil palm small-scale farmers occupy about 80% of the total cultivated area in Ghana. The large oil palm estates such as Benso Oil Palm Plantation. Limited (BOPP), Twifo Oil Palm Plantations Limited (TOPP) and Ghana Oil Palm Development Company Limited (GOPDC) among others constitute the remaining 20% in Ghana (MASDA, 2010). The crop is cultivated as a monocrop by the large estates and their affiliated smallholders. The large estates inter-plant the oil palm interrows with cover crops for the purpose of conserving soil moisture, suppress-.
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