Responses of Cereals to Fertilizers in Northern Nigeria. II. Maize

Summary Field trials in Northern Nigeria have shown that the yield of introduced varieties of maize can be economically improved with combinations of nitrogen and phosphorus fertilizer. Three response areas have been defined. In the south, where most of the maize is grown, the initial response is to nitrogen. Further north, with the exception of one small area in which the response is almost entirely to phosphorus, phosphorus and nitrogen and equal limiting factors. Estimates of the most profitable combinations of nitrogen and phosphorus to use in each area have been obtained from quadratic response surfaces fitted to the yield data of the experiments.