Effect of quantity and placement distances of inorganic 15-15-15 fertilizer in improving soil fertility status and the performance and yield of maize in a tropical rain forest zone of Nigeria.

The high cost of mineral fertilizer in crop production had necessitated an investigation into the optimum fertilizer rate for profitable maize production. The study was conducted in Akure (7°15’N, 5°12’E) in Nigeria in 2007 and revalidated in 2008. The experimental design was a split plot method in a randomized complete block with fertilizer quantity as the main plot and fertilizer placement distance of maize plant as the sub plots. The NPK 15-15-15 fertilizer rates in the main plot were 0,150,200,250 and 300 kg NPK/ha, while distances of application of the maize plants that formed the subplots were 10, 15 and 20 cm. Improved maize growth parameters were observed in plots treated with fertilizers at 300 and 250 kg per hectare and at placement distances of 10 and 15 cm with higher yield and corresponding higher net revenue. The economic analysis confirmed the efficient use of fertilizer to lift small holder maize farming from subsistence levels to a more business-oriented agricultural economy.    Key words: Optimum fertilizer use, inorganic fertilizer, soil fertility, maize performance and yield