EFFECTS OF DIFFERENT NITROGEN SOURCES AND VARYING ORGANIC FERTILIZER RATES ON THE PERFORMANCE OF MAIZE (Zea mays l.) IN EKITI STATE, SOUTHWESTERN NIGERIA

Abstract

A two – year field experiment was conducted at the Teaching and Research Farm of the University of Ado - Ekiti, Nigeria, during the 2006 and 2007 cropping seasons to appraise the influence of different N – sources, organic fertilizer rates, and the interactions between these two factors on growth and yield indices of maize (Zea mays L.). The design was a split – plot, laid out in a randomized complete block, with three replicates. N sources constituted the main – plot treatment, namely: control, urea, calcium ammonium nitrate (CAN), and NPK 15-15-15. Organic fertilizer rates constituted the sub – plot treatment, which were: 0 (control), 2, 4, 6, and 8 t ha^-1.  The results indicated that there were significant differences (p≤ 0.05) between the treatments in growth and yield parameters of maize. The two – year average values indicated that N - sources significantly increased maize leaf area from 0.52 m²/plant for control to 0.74, 0.91 and 1.04 m²/plant for urea, CAN, and NPK, respectively. Similarly, organic fertilizer rates significantly increased maize leaf area from 0.48 m²/plant for 0 (control) to 0.66, 0.79, 0.93 and 1.09 m²/plant for 2, 4, 6, and 8t ha^-1, respectively. N – sources significantly increased maize grain yield from 1.94 t ha^-1 for control to 3.78, 5.27, and 6.47 t ha^-1 for urea, CAN and NPK, respectively. Similarly, increase in organic fertilizer rates resulted in a significant increase in maize grain yield from 1.67t ha^-1 for 0 (control) to 2.03, 2.50, 3.06 and 3.72t ha^-1 for 2, 4, 6, and 8t ha^-1, respectively. The interactions between N sources and organic fertilizer rates significantly increased growth and yield components of maize. The treatment combination of NPK fertilizer and 8 t ha^-1 organic fertilizer resulted in the highest values of growth and yield components of maize in both years.