Nitrogen (N) leaching as the major N loss pathway in intensive agricultural systems. However, a comprehensive evaluation for the effects of organic fertilizer substitution on nitrate residue and leaching losses during the fallow season is not available in winter wheat-summer fallow rotation system. The present dryland wheat fertilization experiment conducted from 2014−2019 adopted a split-plot design, with manure dosage (i.e., M0; NPK group and M1; MNPK group) as the main plots and nitrogen fertilizer dosage as the subplot (i.e., N0, N75, N150, N225, N300). In short, the peaks of NO3− in the 0−200 cm profile gradually move toward the deep soil layer with increasing years of fertilization, and the number of peaks also gradually increases. Increasing the N rate always leads to a sharp increase in nitrate residue in the 0−200 cm profile at the harvest stage (HNR) and sowing stage (SNR) and results in a large amount of nitrate leaching loss (ΔNR) during the summer fallow season, especially when the N rate was> 150 kg ha−1. Compared to NPK, MNPK significantly increased SNR and ΔNR by 38.1 % and 171 %, respectively, but decreased HNR by 36.2 %. ΔNR was positively related to fallow season precipitation and soil water storage changes during the fallow season in the 0–200 cm profile. When the N rate was> 150 kg ha−1, the growth rate of grain yield slowed down or even decreased, and the annual average yields of N75, N150, N225, and N300 were 36.3 %, 51.5 %, 55.4 %, and 47.6 % higher than that of N0, respectively. The average grain yield of MNPK was 13.9 % higher than that of NPK. Therefore, manure combined with 150 kg ha−1 N fertilizer is the best fertilization strategy to ensure high productivity of dryland wheat, control nitrate residue, and reduce nitrate leaching loss during the summer fallow season. This results provided valuable information for the application prospect of N fertilizer reduction combined with manure in dryland agriculture.

中文翻译：

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氮肥联合管理对冬小麦-夏休耕轮作系统产量和硝酸盐动态的影响


氮 （N） 浸出是集约化农业系统中的主要氮损失途径。然而，在冬小麦-夏休耕轮作系统中，尚无对休耕季节有机肥替代对硝酸盐残留和淋失损失影响的综合评价。目前在 2014-2019 年进行的旱地小麦施肥试验采用裂地设计，粪肥用量（即 M0;NPK 组和 M1;MNPK 组）为主样地，氮肥用量为子样地（即 N0、N75、N150、N225、N300）。简而言之，随着施肥年限的增加，0−200 cm 剖面中 NO3− 的峰值逐渐向深层土壤层移动，峰值的数量也逐渐增加。增加氮肥用量总是导致收获期 （HNR） 和播种期 （SNR） 0-200 cm 剖面中硝酸盐残留量急剧增加，并导致夏季休耕季节大量的硝酸盐浸出损失 （ΔNR），尤其是当氮肥用量为 > 150 kg ha-1 时。与 NPK 相比，MNPK 显著增加了 SNR 和 ΔNR，分别增加了 38.1% 和 171%，但 HNR 降低了 36.2%。ΔNR 与 0–200 cm 剖面休耕期休耕季节降水和土壤储水变化呈正相关。当氮肥用量为> 150 kg ha−1时，籽粒产量生长速度减慢甚至下降，N75、N150、N225和N300的年平均产量分别比N0高36.3 %、51.5 %、55.4 %和47.6 %。MNPK 的平均粮食产量比 NPK 高 13.9 %。 因此，粪肥与 150 kg ha−1 N 肥料相结合是确保旱地小麦高产、控制硝酸盐残留和减少夏季休耕季节硝酸盐浸出损失的最佳施肥策略。研究结果为减氮配肥在旱作农业中的应用前景提供了有价值的信息。