Asian Journal of Soil Science and Plant Nutrition

Decisions concerning optimum rates of fertilization directly involve fitting some type of rates to yield when several rates of fertilizer are tested. This study was carried out to investigate the effects of nitrogen fertilizer rates yields and yield components of bread wheat and determine optimum rate of N. The field experiment was carried out in 2016 and 2017 main cropping season at Tsegedie and Welkait districts in Western Tigray Regional State, Ethiopia. The experiment consists of seven levels of nitrogen (0, 23, 46, 69, 99, 115 and 138 kg ha^-1) arranged in randomized completed block design with three replications. Nitrogen was applied splits, half at planting and remaining at tiller stage. NPSB was applied as basal application for all experimental plots except the negative control. Soil samples were collected before planting for analysis of some selected physicochemical properties. The soil properties of the experimental sites of the two districts varied in most of the soil properties. Application of nitrogen significantly influenced grain yield and yield components of wheat in both study sites. The highest grain yield 3926 kg ha^-1 and 2131 kg ha^-1 were obtained from 138 kg N ha^-1 and 115 kg N ha^-1 at the study sites of Tsegedie and Welkait districts, respectively. Highest marginal rate of returns were however obtained at nitrogen rates of 46 kg ha^-1 and 23 kg ha^-1 at Tsegedie and Welkait districts, respectively. Hence, it could be concluded that the use of N at 46 kg ha^-1and 23 kg ha^-1 with 100 kg NPSB fertilizer could give optimum bread wheat yield at Tsegedie and Welkait districts, respectively.