Response of Maize Grain Yields to Rates and Split Applications of Nitrogen and NPK Combinations in the Southern Guinea Savanna of Nigeria

Abstract

Two field experiments were conducted on the field at Minna , Southern Guinea Savannah agro ecological zone to investigate the response of maize grain yields to different rates and split applications of nitrogen and NPK combinations. The two experiments had a split plot design fitted to a randomized complete block with three replicates. The main plots in the two experiments were the levels at 30, 60, 90 and 120 kg ha-1 and NPK. The subplots were the three methods of splits applications, single, twice, and three times. The soil of the site has inherent medium fertility status. There was no response of grain yields to nitrogen fertilization. Application of full dose of nitrogen at planting time gave significantly (P< 0.05) higher grain yield than three split applications. Grain yield of 4574 kg ha-1 was obtained with application of 90kg N ha-1 in full while 5448 kg ha-1 was obtained with 90kg NPK ha-1 which was significantly (P< 0.05) higher than 5523kg and 2906 kg ha-1 produced by application of 30 and 60 kg NPK ha-1 respectively. The rate of 90 kg NPK ha-1 seems to be the optimum for maize in the soil. Comparatively higher grain yields were produced by NPK combinations than nitrogen alone suggesting that maize respond to nitrogen with adequate supply of phosphorus and potassium.