Effect of different split applications of npk fertilizer on growthand yield of maize, and economic returns.
Declining inherent soil nutrient, poor grain yield of maize, delayed supply and high cost of inorganic fertilizer, call for proper timing of application, to optimize the use of this scarce resource in maize production in Nigeria. A field experiment was carried out in the 2007 and 2008 cropping seasons in the University of Agriculture, Abeokuta to investigate the effect of different split applications of NPK fertilizer 20:10:10 on growth and yield of maize. Six treatments laid out in Randomized complete Block Design (RCBD) consisted of 600 kg/ha of NPK 20:10:10 in 2007 and 300 kg/ha in 2008, applied at 2 and 6 WAP (Week after planting), 2 and 8 WAP, 4 and 6 WAP, 4 and 8 WAP, 6 and 8 WAP and no fertilizer (control). Plant height, grain yield, cob length, cob girth, hundred grain weight were all significantly affected (p< 0.05) by different split application. Fertilizer application increased grain yield by 135 260% and 67 191% in 2007 and 2008 respectively. Application of fertilizer at 2 and 8 WAP consistently gave the highest significant grain yield. In 2008, delaying first dose of fertilizer till 6WAP increased grain yield but was not economical. Split application of 300 kg/ha fertilizer, at 2 and 8WAP gave higher economic return than application of 600 kg/ha at 4 and 6WAP or 4 and 8WAP. It was concluded that maize grain yield can be maximized if fertilizer is applied at 2 and 8 WAP, while delayed application of 300 kg/ha of fertilizer till 6WAPcould lead to economic loss.
Keywords: Fertilizer, split application, maize