Response of Maize to Combined Application of Nitrogen and Phosphorus Fertilizer Under Different Weeding Regimes in Makurdi in the Southern Guinea Savanna Zone of Nigeria

The effect of combined different levels of nitrogen with different levels of phosphorus and weeding regimes was examined at the Teaching and Research Farm of the Federal University of Agriculture, Makurdi. Different levels of nitrogen were combined with different levels of phosphorus to give a single inorganic fertilizer treatment, namely control (no application), 20KgN + 10KgP/ha, 30KgN + 20KgP/ha, 20KgP/ha, 40KgN + 30KP/ha and 50KgN + 40KgP)/ha. These were combined with weeding regimes as follows: W (no weeding), 1 W (weeding once, 3WAP), W (weeding twice, 3 and 6 WAP) and W (weeding thrice, 3 and 6 and 9 WAP) 2 3 4 to give a total treatment combination of twenty treatments. Results indicated significant differences among parameters and seed yield upon application of combined levels of Nitrogen and Phosphorus. Similarly, weeding regimes significantly increased growth parameters and maize seed yield. Weeding thrice (3, 6 and 9 WAP) gave higher grain yield than all other treatments. Treatment combination was also significant. Treatment combination of 50KgN + 40KgP/ha + weeding thrice (3, 6 and 9 WAP) produced the highest maize yield in both years. It is recommended that 50KgN + 40KgP/ha and thrice weeding regimes be adopted to high yield of maize in the study area.