This study was undertaken in two distinct ecological zones of Edo state of Nigeria to determine the effects of N:P:K ratios applied to the soils on the availability of N, P, K and on yield of maize. The sites used were Rubber Research Institute of Nigeria (RRIN) Iyanomo (Rain forest) and the Teaching and Research Farms of Ambrose Alli University, Emaudo, Ekpoma (derived savanna). Soils from both sites were analyzed for both physical and chemical properties before the commencement of the

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... nts. The experiments were carried out as: Pot and Field experiments. Each of the experiments had ten treatments (adjusted ratios) that were fitted into randomized complete block design and replicated three times, with maize as the test crop. Results from pot experiment in the screen house revealed that N:P:K ratio 4:1:1 had the highest dry matter yield for both locations, (RRIN; 7.10 g/pot and Emaudo; 6.33 g/pot) but these values were not significantly different (P < 0.05) from what were obtained from N:P:K ratio 3:1:1 and 2:1:1, respectively. The N:P:K ratio in soil had influence on the availability of N,P and K. Under field conditions, N:P:K ratio 3:1:1 had the highest grain yield for both locations (RRIN; 5.54 ton/ha and Emaudo; 5.25 ton/ha). The N:P:K ratio 3:1:1 was the best ratio with the highest yield for both locations and is therefore suggested for these soils.