Nitrogen Accumulation, Use Efficiency, and Productivity of Wheat (Triticum aestivum L.) as Influenced by Different Rates of Nitrogen in Lalitpur, Nepal

Appropriate application of nitrogen (N) not only increases wheat production but also results in optimum N use efficiency (NUE). An experiment was conducted to determine the N concentration, uptake, use efficiency, and performance of wheat in response to N fertility levels at Khumaltar, Lalitpur, Nepal, during 2019/20 and 2020/21. The experiment involved 7 treatments; 6 levels of N (0, 50, 75, 100, 125, and 150 kg ha(-1)) with application of P2O5:K2O in 50:50 kg ha(-1), and zero plot (no fertilizer application), which was laid out in randomized complete block design and replicated three times. The varying N had a significant influence on grain yield, N concentration, its uptake, NUE, and the economics of wheat production. Two years of pooled grain yield showed significantly (p <= 0.001) higher grain yield (6.52 Mg ha(-1)) with a B: C ratio of 2.6, observed from the application of 150 kg N ha(-1), which was at par with the use of N @ 125 kg ha(-1) (6.32 Mg ha(-1)). The 2-year mean N concentration in grain and straw of wheat was 13.98 and 3.49 g kg(-1), respectively. The data revealed that 4.9 Mg ha(-1) grain yield plus 5.56 Mg ha(-1) dry straw yield removed 81.7 kg N ha(-1). Likewise, the N partition in wheat grain and straw was 75% and 25% respectively. The mean partial factor productivity, internal efficiency, physiological efficiency, recovery efficiency, and agronomic efficiency of N in wheat were found to be 61.8 kg kg(-1), 59.1 kg kg(-1), 53.1 kg kg(-1), 45.0%, and 22.5 kg kg(-1), respectively. N was a limiting nutrient as added N fertilizer had a considerable impact on wheat production and the use of 125 kg N ha(-1) was recommended under similar soil properties and ecology.