Productive Impact of Residual Nutrients (N and P) in Maize and Soybean Rotation

Agricultural intensification has resulted in severe soil nutrient depletion in Africa. Alternative agricultural practices have been promoted to restore and sustain soil fertility. Use of mineral fertilizer alongside different cropping systems has been particularly promising. This study was conducted in the Guinea savannah zone of Ghana during the 2015 and 2016 cropping season (July to November) to assess the performance of soybean and maize in a rotation system. In season one, using randomized complete block design the treatments were, soybean (without treatment), inoculated soybean, soybean with phosphorus application, inoculated soybean with phosphorus application and maize. During the second season, the first season experimental plots served as main-plots and divided into four sub-plots on which maize planted and treated with four nitrogen rates in a split plot design. The results show that soybean production leads to significant increase in residual soil nitrogen content of about 16kg/ha to 55kg/ha, which is about 28 folds higher than that observed in maize fields. The level of Residual N was enhanced with inoculation. Phosphorus application during the first season of maize cultivation led to increases in residual P levels, which had a positive impact on yield of soybean in the second season. Grain yield of maize that followed soybean in a rotation system performed better than maize that followed maize at various fertilizer rates. This shows that, the residual N and P helps maize and soybean respectively in a rotation system which makes it highly economical.