Agricultural ammonia (NH₃) emissions significantly reduce nitrogen (N) use efficiency (NUE) and adversely affect environmental quality. There is thus much interest in mitigating NH₃ emissions through appropriate N fertilizer and water management in winter wheat. A two–year field study –was conducted to quantify the recovery of ¹⁵N–labelled N fertilizer and to investigate the NH₃ flux, grain yield, yield–scaled NH₃ emissions, NUEs and water use efficiency (WUE) among different N application rates (0, 120, 240, and 360 kg N ha^–1, abbreviated as N0, N120, N240 and N360, respectively) under rain–fed and supplemental irrigation condition. The peak daily NH₃ emissions reached 2–8 DAS after basal N fertilizer application, and the fluxes decreased to relatively low levels thereafter. Most NH₃ volatilization (> 90%) occurred within one month after sowing. The maximum accumulative NH₃ emission was 66 kg N ha^–1 in N360, which was increased by 104%, 2–fold and 12–fold compared with N240, N120 and N0, respectively, averaged across water regimes and experimental years. The NH₃ emission factor (%) of N360 was significantly increased by 43% and 77% compared with the other two N application rates (N120 and N240) under rain–fed and supplemental irrigation regimes, respectively. Water regimes did not have a significant effect on NH₃ fluxes or NH₃ emission factors (%). Grain yield, WUE and yield–scaled NH₃ emissions generally increased with increasing N application rate, and the highest values were achieved under N120 or N240 regardless of the water regimes. All NUE traits were reduced, and the ¹⁵N residue in the soil profiles increased with increasing N application rates under both water regimes. The results suggested that high NH₃ emissions were the major reason for inferior NUE, which was further confirmed by the ¹⁵N stable isotope. Overall, the medium N rate (120–240 kg N ha^–1) is the optimal rate for achieving a high yield of 8 t ha^–1, as further increases in N rates fail to produce significantly higher yield, and even increase NH₃ emissions, lead to the deterioration of WUE and NUE, and cause serious environmental costs.

农业氨 (NH ₃ ) 排放显着降低氮 (N) 使用效率 (NUE)，并对环境质量产生不利影响。因此，在冬小麦中通过适当的氮肥和水管理来减少 NH ₃排放引起了很大的兴趣。进行了为期两年的田间研究，以量化¹⁵ N 标记的氮肥的回收率，并调查不同施氮中 NH ₃通量、粮食产量、产量比例的 NH ₃排放、NUE 和水分利用效率 (WUE)率（0、120、240 和 360 kg N ha ^–1，分别缩写为 N0、N120、N240 和 N360）在雨养和补充灌溉条件下。每日峰值 NH ₃施氮肥后排放量达到2-8 DAS，此后通量下降到相对较低的水平。大多数NH ₃挥发（> 90%）发生在播种后1个月内。N360 中最大累积 NH ₃排放量为 66 kg N ha ^–1，与 N240、N120 和 N0 相比，在不同水体和实验年份中平均分别增加了 104%、2 倍和 12 倍。与其他两种施氮量（N120 和 N240）相比，在雨养灌溉和补充灌溉制度下，N360的 NH ₃排放因子（%）分别显着提高了 43% 和 77%。水情对 NH ₃通量或 NH ₃没有显着影响排放因子（%）。谷物产量、WUE 和按产量衡量的 NH ₃排放量通常随着施氮量的增加而增加，并且无论水情如何，在 N120 或 N240 下都能达到最高值。所有 NUE 性状都降低，土壤剖面中的¹⁵ N 残留量随着施氮量的增加而增加。结果表明，高 NH ₃排放是 NUE 较差的主要原因，¹⁵ N 稳定同位素进一步证实了这一点。总体而言，中等施氮量（120–240 kg N ha ^–1）是实现 8 t ha ^–1高产的最佳施肥量，随着氮率的进一步增加无法产生显着更高的产量，甚至会增加NH ₃排放，导致WUE和NUE的恶化，并造成严重的环境成本。