Abstract

Tilahun Tadesse1, Alemayehu Assefa, Minale Liben and Zelalem Tadesse

An experiment was conducted at Adet Research station, northwest-Ethiopia in order to determine the influence of the application time of nitrogen fertilizer on two varieties of maize (Zea mays). A split plot design in randomized complete block (RCB), with three replicates was used. Variety was the main plot and fertilizer application time the sub-plot. Intermediate maturing and late maturing maize varieties, BH-540 and BH-660, respectively, were used for the experiment. Ten different times of nitrogen fertilizer application were studied: 1/2 at planting (p) + 1/2 at knee height (k) (control), all at planting, 1/2 p + 1/2 near tasseling (t), 1/3 p + 1/3 k + 1/3 t, 1/3 p + 2/3 k, 1/3 p + 2/3 t, 1/4 p + 2/4 k + 1/4 t, 1/4 p + 1/4 k + 2/4 t, 1/4 p + 3/4 k, and 1/4 p +3/4 t. The same rate of nitrogen, 128 kg N /ha, was used in all the cases. Results obtained indicated that for the intermediate maturing BH-540 variety nitrogen application of 1/3 at planting + 2/3 at knee height was found to produce the highest yield. The application method gave a yield advantage of 1005 kg/ha over the commonly practiced 1/2 at planting + 1/2 at knee height application. Concerning the late maturing variety BH-660, nitrogen application of 1/4 at planting + 3/4 at knee height gave a yield advantage of 296.2 kg/ha over 1/2 at planting + 1/2 at knee height application. The best yielding split applications and timings exhibited the highest agronomic Nutrient Use Efficiencies (NUE) and better economic advantages for the respective varieties