Optimized Drip Fertigation Scheduling Improves Nitrogen Productivity of Winter Wheat in the North China Plain

Traditional methods of water and fertilizer application are the main cause of nitrogen (N) losses through ammonium volatilization, leaching, and greenhouse gas emissions. This problem could be addressed with the use of drip fertigation techniques, which ensure the integration of irrigation and fertilization technologies. However, current results on drip fertigation scheduling of winter wheat (Triticum aestivum L.) under a single nitrogen application rate are lacking. A 2-year field experiment was conducted to determine the responses of wheat yield, nitrogen uptake, and nitrogen use efficiency (NUE) indices to different fertigation schedules under a drip irrigation system. A total of 240 kg N ha(-1) was split between sowing (basal N), jointing (first topdressing N), and booting (second topdressing N) stages. The treatments were N0-0 (0% basal and 0% topdressing), N0-100 (0% basal and 100% topdressing), N25-75 (25% basal and 75% topdressing), N50-50 (50% basal and 50% topdressing), N75-25 (75% basal and 25% topdressing), and N100-0 (100% basal and 0% topdressing). The grain yield (GY) obtained in the N50-50 was significantly higher than that in the N0-100 (11.24%), N25-75 (8.27%), N75-25 (9.00%), and N100-0 (22.13%). Similarly, the N50-50 improved total N uptake by 6.54% (N25-75), 9.36% (N75-25), 17.73% (N0-100), and 32.96% (N100-0). The agronomic efficiency (AE), apparent recovery efficiency (APE), and nitrogen partial factor productivity (PFP) were higher in N50-50. Moreover, a principal component analysis (PCA) showed that the N50-50 had the highest ranking at 91.20% over 2 years of study. Applying 50% of 240 kg ha(-1) (urea) at sowing and splitting the balance between jointing and booting stages is desirable for maximum grain yield and proper utilization of nitrogen fertilizer.