Assessment of the nitrogen requirements of maize (Zea mays L.) in Southern Guinea Savanna agroecology of Nigeria

During the growing seasons (May to October) of 1987 and 1988 respectively five and four different rates of N were tested on maize (Zea mays L.) at 12 different field sites across the Southern Guinea Savanna of Nigeria. Nitrogen was applied through granular urea (size +14 mesh), ordinary prilled urea (–35 mesh) and calcium ammonium nitrate. Marked differences existed among experimental sites in maize grain yield response to N with Yelwa and Ta-Hoss in Plateau State having the highest response at 60 and 90 kg N ha^–1 respectively.During 1988, at five experimental sites the yield was maximized with 120 kg N ha^–1, while at three other sites the yield maximization occurred at 90 kg N ha^–1. During 1987, the corresponding number of sites was two and six with 120 and 90 kg N ha^–1 rates, respectively. Plant height and cob number exhibited a linear relationship with yield. Differences in yield in response to application of different N sources were non-significant.Contribution from the Nationally coordinated fertilizer use programme funded by Federal Government of Nigeria