Residual Nitrogen Contributions from Grain Legumes to the Growth and Development of Succeeding Maize Crop

Field experiment was conducted at the Institute for Agricultural Research Farm at Samaru, Nigeria in 2008 and 2009 rainy seasons to investigate the residual nitrogen contributions by four legume crops (soyabean, cowpea, lablab, and groundnut) to the growth and development of succeeding maize given four levels of nitrogen fertilizer (0, 40, 80, and 120 kg N ha −1 ). In 2008, the treatments consisted of four legumes, maize and a fallow period. The six treatments were laid out using randomized complete block design replicated four times. In 2009, maize crop was planted on the previous crops’ plots and fallow. The experimental design used was split-plot with previous legumes, maize, or fallow as main plots, and the four nitrogen fertilizer treatments as subplots. Results obtained showed that nitrogen availability in the top soils of the previous legumes and fallow compared with that of maize plot was increased by 250, 200, 170, 107 and 157% after lablab, groundnut, cowpea, soyabean and fallow, respectively. Maize grown on previous lablab plot significantly recorded higher growth characters compared with maize following other legumes and fallow. Growth of maize was highest with the application of lower rates of nitrogen after lablab and groundnut compared with maize after maize.