Optimizing N-fertigation scheduling maintains yield and mitigates global warming potential of winter wheat field in North China Plain

Traditional methods of nitrogen fertilizer (urea) application are major causes of poor nitrogen use and serious greenhouse gas emissions (GHG), which translates into global warming. Rational scheduling of nitrogen fertilization is critical for the mitigation of greenhouse gas emissions as well as ensuring sustainable food production. There is little information on the coupled analysis of global warming potential (GWP) and grain yield (GY) of winter wheat under a drip fertigation system. A two-year field experiment was conducted to determine the effect of split fertigation of nitrogen on GWP and yield of drip-irrigated winter wheat. The 5 levels of nitrogen schedule were as: N0-100 (all N fertilizer was applied as topdressing N), N25-75 (25% as basal N and 75% as topdressing N), N50-50 (50% as basal N and 50% as topdressing N), N75-25 (75% as basal N and 25% as topdressing N), and N100-0 (all N fertilizer was applied as basal and 0% topdressing N). The total nitrogen rate was 240 kg ha(-1). The basal N doses were spread just before sowing and the topdressing N doses were applied through a drip fertigation system. The results revealed that N schedule significantly (P < 0.05) affected GHG (CO2, CH4 and N2O) emissions, GWP, GY, and subsequently the greenhouse gas intensity (GHGI). The lowest GWP (125.34 kg CO2 eq. ha(-1)) and GHGI (15.01 kg CO2 eq. Mg-1) were observed in N50-50 and N25-75 N scheduling, respectively. Compared with N100-0, the N scheduling of N25-75 and N50-50 significantly (P < 0.05) reduced GWP by 67.67 and 63.48%, respectively. A significantly higher yield (9.09 tons ha(-1)) was observed in the N50-50 treatment. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) specified that N50-50 N schedule provides the best results for minimized GWP at an acceptable GY. Therefore, the scheduling of 50% applied as basal N and other 50% as topdressing N through N-fertigation would be recommended for sustainable wheat production at a reduced risk of global warming in the North China Plain.