Evaluation of Agronomic Performance of Maize (zea Mays L.) Under Different Rates of Npk Fertilizer Application in an Ultisol of Lafia, Nassarawa State

The study was carried out in Lafia, Nassarawa State with the view to determine the optimum fertilizer rate for maize production among the Ultisols. The hybrid maize, Oba super II was used as a test crop while commercial NPK (15:15:15) fertilizer at the rates of 0: 0: 0, 60: 30: 30, 90: 45: 45, 120: 60: 60 and 150: 75: 75 kg/ha representing 0.48, 0.72, 0.96 and 1.20 kg/ha were applied to the hybrid maize, “Oba super II”. The soils were well drained with sandy loam texture while structural aggregates were poor to weak. The soils were low in cation exchange capacity, basic cation (Ca, Mg, K and Na), total nitrogen, available phosphorus and organic carbon. They were low in micronutrient and therefore, low in their inherent fertility status. Uptake and utilization of applied fertilizer in both years witness better responses compared with the non-fertilized plants. NPK 60:30:30 kg/ha yielded highest (65.60 cm and 13.14) plant height and number of leaves while leaf areas and leaf area index were highest (5.52 m2 and 0.46 m2) at NPK 120:60:60 kg/ha. The stem diameter was highest (94.50 mm) with the use of NPK 150:75:75 kg/ha. In terms of yield parameters, ear weight and ear length were highest (90.00 g and 10.64 cm) at NPK 150:75:75 kg/ha while ear diameter and grain yield were highest (123.94 cm and 1.06 kg) with the use of NPK 90:45:45 kg/ha Grain yield advantages were successfully maximized with the use of NPK 90:45:45 Kg/ha