Owens, J., Z. Wang, B.W. Thomas, X. Hao, K. Coles, E. Rahmani, R. Karimi, K. S. Gill and B. L. Beres. 2023.
To evaluate how enhanced efficiency liquid nitrogen (N) fertilizers affect winter wheat (Triticum aestivum L.) production under irrigated and rain-fed environments, experiments were conducted at two irrigated and five rain-fed sites across the Canadian Prairies from 2013 to 2018 (22 site-years). The N fertilizers included urea ammonium nitrate (UAN) treated with 1) urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT), 2) NBPT plus nitrification inhibitor dicyandiamide (DCD) and 3) nitrification inhibitor nitrapyrin (Nitrapyrin), as well as untreated UAN and urea, and polymer-coated urea (PCU). All fertilizers were applied by banding 50% at planting and 50% in-crop in early-spring, except PCU where PCU was applied at planting and urea applied early-spring. Nitrous oxide (N2O) emissions and methane (CH4) uptake were measured at one rain-fed site from 2014 to 2017. NBPT increased grain yield by 1.2-14.0% and 2.8-4.0% under irrigated and rain-fed environments, respectively, relative to all the other N sources except untreated urea in the rain-fed environment. Total N uptake with NBPT was between 0.0% and 11.8% higher than the other N sources across irrigated and rain-fed environments. The results suggested that both grain yield and N use efficiency were optimized when UAN contained a urease inhibitor. All liquid EEFs produced grain protein content greater than 11%, except Nitrapyrin under irrigated environments. Data from three site-years indicated that greenhouse gas emissions were unaffected by N source under rain-fed conditions. Liquid UAN with a urease inhibitor may have the most potential to optimize winter wheat production and N use efficiency in the Canadian Prairies.
