Optimizing water and nitrogen management to reduce basal nitrogen inputs, improve nitrogen uptake and utilization efficiencies, and achieve high yields and low soil nitrate residue in wheat production

Excessive basal nitrogen (N) inputs and improper water management limit both wheat yields and N use efficiency. Thus, a field experiment was conducted for two years to evaluate whether optimizing water and N management could reduce basal N inputs, improve N uptake and utilization efficiencies (NUpE and NUtE), and achieve high yields. A split-plot design was employed with water and N management as the main plots (conventional water and N management, CM; and drip fertigation, DF) and basal N rates as the sub-plots (150, 125, 100, 75, 50, 25, and 0 ​kg ​ha −1 , designated as B150, B125, B100, B75, B50, B25, and B0, respectively), while maintaining a fixed topdressing N rate of 150 ​kg ​ha −1 . The results showed that DF increased the average yield by 12.7–15.9% compared with CM due to improvements in N absorption, tillering ability, ear and grain numbers, leaf area index, and biomass production. More importantly, DF reduced the sensitivity of yield to the basal N rate. Halving the basal N rate from B150 to B75 reduced the yield by 4.1–4.3% under DF (P ​> ​0.05), but the yield loss was 10.9–11.4% under CM (P ​< ​0.05). Under DF, the increased grain weight compensated for the reduced grains m −2 , but under CM, the 17.3–17.8% reduction in grains m −2 was not fully offset by the increase of 8.4–9.9% in the grain weight. In addition, the increased NUpE and NUtE also contributed to relatively high yield at B75 under DF. Furthermore, the NO 3 − -N residue under DF was 7.9–9.8% lower at B75 than at B150. In conclusion, DF combined with a reduced basal N rate is effective for increasing wheat production, while decreasing soil nitrate residual levels to mitigate environmental impacts. • Drip fertigation enhances wheat N uptake and yield and decreases nitrate residue. • Reducing basal N rate increased N utilization efficiency but might hinder yield. • Adopting drip fertigation with reduced basal N is recommended for wheat production.