Pivotal impact of sources and rates of nitrogen fertilizers on yield, nitrogen use efficiency in bread wheat cultivars

Wheat is considered as one of the main agricultural cereals worldwide, used in human and animal feed. The goal of this research was to investigate the pivotal impact of using different sources and rates of nitrogen fertilizer on the productivity of wheat cultivars in two growing seasons 2015/2016 and 2016/2017 to find out alternatives for wheat farmers. A strip-split plot experimental design was used with three rates of nitrogen fertilization (119, 166 and 240 kg ha-1), three nitrogen sources (ammonium sulphate, ammonium nitrate and urea) and three wheat cultivars (Giza 168, Sakha 93 and Sakha 94). A number of variables such as number of grains spike-1, 1000-grain weight, number of spikes m-2, grain yield, harvest index, percentage of apparent recovery N of fertilizer and agronomic NUE were assessed. Results showed that Sakha 94 was superior than Giza168 and Sakha 93 in all yield-related traits. N fertilizer rate had a more consistent effect on yield-related traits. Applied 240 kg N ha-1 resulted in increased number of grains spike-1, 1000-grain weight as well as number of spikes m-2 in both seasons furthermore grain yield and harvest index, % apparent recovery N of fertilizer and agronomic NUE declined with increment of N rates. The application of sources of N fertilizer seems to play a pivotal role. Application of ammonium sulphate resulted in positive impact on all traits than other sources of nitrogen. It was concluded that grain yield enhanced by Sakha94 cultivar with 240 kg N ha-1 of ammonium sulphate.