Yield Response of Maize (zea Mays L.) and Soil Nutrients to Time and Methods of Npk Application

A study was carried out at the Teaching and Research Farm of the University of Ado-Ekiti, Nigeria, during early 2008 and 2009 cropping seasons to determine the effects of time and methods of NPK fertilizer application on yield of maize (Zea mays L.) and soil nutrients. The design was split – plot, laid out in a Randomized Complete Block, with three replicates. Time of NPK fertilizer application constituted the main – plot treatments, while the method of NPK fertilizer application was the sub-plot treatment. The main-plot treatments were: no fertilizer application (NFA) i.e. control, single early application (SEA) at four weeks after planting (WAP), two split applications (SA), with half applied at 4 WAP, and the rest half at 8 WAP and single late application (SLA) at 8 WAP. The methods of NPK fertilizer application were band placement and broadcast methods. The results indicated that there were significant (P – 0.05) differences between the two treatments as regards their effects on yield and yield components of maize. The percentage decreases in soil organic carbon (SOC), adduced to time of NPK fertilizer application were 38, 44, 48 and 40 for NFA, SEA, SA and SLA respectively. SLA resulted in a 60% increase in total N, contrasting decreases of 36, 26 and 29% for NFA, SEA and SA respectively. Similarly, SLA resulted in a 62% increase in available P, as against decreases of 26, 16 and 21% for NFA, SEA and SA respectively. Time of NPK fertilizer application significantly (P = 0.05) increased maize grain yield from 2.79 t ha-1 for NFA to 4.15, 4,43 and 3.13 t ha-1 for SEA, SA and SLA, respectively. Band placement of NPK fertilizer gave 4.10 t ha-1 maize grain yield, which was significantly higher than 3.75 t ha-1 obtained for the broadcast method counterpart.