Background Improving crop yield while mitigating nitrogen application and water-saving has become increasingly important in recent years. Excessive nitrogen and irrational irrigation lead to nitrogen loss and nitrate accumulation in the soil, and nitrate leaching varies with annual precipitation. This study aimed to evaluate effects of nitrogen rate and supplemental water on nitrate distribution, and nitrogen absorption and utilization by winter wheat in different pre-sowing stored soil water. Methods A split-split plot experiment was conducted for two wheat seasons using three pre-sowing stored soil waters (S1: 350 mm, S2: 450 mm, and S3: 650 mm), four nitrogen rates (N0: 0, N105: 105 kg ha −1 , N210: 210 kg ha −1 , and N315: 315 kg ha −1 ), and four supplemental waters (W0: 0, W1: 56.3 mm, W2: 78.1 mm, and W3: 100 mm). Conclusion The results showed that higher pre‑sowing stored soil water increased soil NO₃⁻‑N content throughout the profile, but also enhanced crop uptake, thereby reducing residual nitrate in the deepest layer under S3 treatment. Nitrogen rate was the dominant factor influencing nitrate leaching, with N210 and N315 markedly increasing NO₃⁻‑N accumulation in the 80‑160 cm layer. Grain yield peaked at N105W3 under S1 treatment, and at N210W3 under S2 and S3 treatments, while excessive nitrogen (≥ 315 kg ha⁻¹) reduced both yield and nitrogen use efficiency (NUE). NUE increased with moderate nitrogen (105–210 kg ha⁻¹) and adequate supplemental water (78.1‑100 mm), but declined when nitrogen or water exceeded optimal levels; the optimal nitrogen rates derived from multi‑objective regression (yield, NUE, leaching) were 105 kg ha⁻¹ (S1), 162 kg ha⁻¹ (S2) and 168 kg ha⁻¹ (S3), achieving high grain yields (1000–5600 kg ha⁻¹) with acceptable nitrate leaching. Suggestion The findings provide a scientific basis for water‑nitrogen management in dryland wheat production, suggesting that “moderate nitrogen and appropriate water” can maximize yield while minimizing environmental risks. effects of different water and nitrogen on nitrate distribution and leaching in soil, nitrogen uptake, utilization and translocation by winter wheat, including three soil water levels (S1 350 mm, S2 450 mm, S3 650 mm), four nitrogen rates (0, 105, 210, 315 kg ha −1 ), four supplemental water levels (0, 56.3, 78.1, 100 mm). Show soil profile with nitrate concentration gradient, wheat plant with nitrogen arrows, yield bar chart, and optimal management recommendation (moderate N and appropriate water). Use clean scientific style, icons, colors blue for water, green for wheat, orange for nitrogen. • Applying 210 and 315 kg ha −1 nitrogen increased soil NO 3 - -N accumulation throughout the profile. • Bath irrigation and nitrogen fertilization significantly affect crop growth and grain yield of winter wheat. • Applying 105 (S1), 162 (S2), 168 (S3) kg ha −1 nitrogen achieves high yields and improved nitrogen use efficiency. • Supplemental water 100 mm at jointing, anthesis and filling is the most effective supplemental irrigation strategy.
Xu et al. (Fri,) studied this question.