Effects of timing and nitrogen fertilizer application rates on maize yield components and yield in eastern Ethiopia

Maize (Zea mays L.) is an important food security crop in Ethiopia. However, low soil fertility and the use of haphazard nitrogen (N) fertilizer with little attention to the rate and timing of N application constrain productivity. Therefore, field experiments were conducted during the 2019 and 2020 cropping seasons to investigate the response of maize to different N application rates and timings. The treatments consisted of six N fertilizer rates (0, 23, 46, 69, 92, and 115 kg N ha(-1)) and four application timings (all at vegetative stages; one-half at sowing + one-half at vegetative stages; one-third at sowing + one-third at vegetative stages + one-third at tasseling; one-fourth at sowing + two-fourths at vegetative stages + one-fourth at tasseling). The experiments were a randomized block design in a factorial arrangement with three replications. The results of the study revealed that ears per plant, ear length, grains per row, grains per ear, stover, and grain yield were significantly (p <= .001) influenced by the interaction effects of N application rates and timings. The highest stover (9.99 t ha(-1)) and grain yield (9.41 t ha(-1)) were obtained from the application of 92 kg N ha(-1) in three split applications of one-fourth at sowing, one-half at vegetative stages, and one-fourth at tasseling. Therefore, it is concluded that 92 kg N ha(-1) in three split applications of one-fourth at sowing, two-fourths at vegetative stages, and one-fourth at tasseling was found to be the most economical in the study area.