Abstract Controlling nitrogen (N) and phosphorus (P) loss from hill slope cropland is crucial to mitigate agricultural non-point source (AGNPS) pollution in the upper Yangtze River basin. However, pathways and loadings of soil N and P loss and their responses to agricultural management practices are not well documented. We conducted a three-year field experiment using the free-drain lysimeters to evaluate the long-term effects of organic amendments on N and P loss from sloping cropland. The field experiment included five experimental treatments: mineral fertilizers (NPK) as a control, fresh pig slurry as organic manure only (OM), crop residues only (CR), organic manure combined with NPK (OMNPK), and crop residues combined with NPK (CRNPK). The results show that organic amendment applications decrease discharges of overland flow and interflow compared with NPK treatment. On average, annual total N (TN) loss loadings ranges from 8.3 to 27.6 kg N ha−1, with 1.1 to 5.2 kg N ha−1 of particulate N (PN), and 6.4 to 19.1 kg N ha-1 of nitrate N (NO3--N) loss loadings, respectively for the five treatments. Thus, PN and NO3--N losses accounts for 13–19 %, and 63–78 % of TN loss loadings, respectively across the five treatments. However, the average annual total P (TP) loss loadings ranges from 0.23 to 0.84 kg P ha−1, with 0.21 to 0.80 kg P ha-1 of particulate P (PP) for the five treatments. Moreover, PP loss accounts for 92–96 % of TP loss loadings across the five treatments. Compared to NPK treatment, organic amendment applications significantly decrease TN loss, by 85 % via overland flow and 117 % via interflow on average. Organic amendment applications also significantly decrease TP loss, by 162 % via overland flow and, by 90 % via interflow compared with NPK treatment on average. This study shows that the combination of mineral fertilizers and organic amendments of either manure or crop residues can mitigate hydrological N and P loss from slope croplands in the upper Yangtze River basin.

中文翻译：

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有机肥施用对长江上游坡耕地氮磷流失的影响

摘要 控制山坡耕地氮（N）和磷（P）损失是缓解长江上游农业面源（AGNPS）污染的关键。然而，土壤氮磷流失的途径和负荷及其对农业管理实践的反应没有得到很好的记录。我们使用自由排水蒸渗仪进行了为期三年的田间试验，以评估有机添加物对倾斜农田 N 和 P 损失的长期影响。田间试验包括五个试验处理：矿物肥料（NPK）作为对照，新鲜猪粪作为仅有机肥（OM），仅作物残留物（CR），有机肥与 NPK 结合（OMNPK）和作物残留物与 NPK 结合(CRNPK)。结果表明，与 NPK 处理相比，有机改良剂的应用减少了地表漫流和互流的排放。平均而言，年总氮 (TN) 损失负荷范围为 8.3 至 27.6 kg N ha-1，1.1 至 5.2 kg N ha-1 的颗粒 N (PN) 和 6.4 至 19.1 kg N ha-1 的硝酸盐 N (NO3--N) 损失负荷，分别为五个处理。因此，在五种处理中，PN 和 NO3--N 损失分别占 TN 损失负荷的 13-19% 和 63-78%。然而，五种处理的平均年总磷 (TP) 损失负荷范围为 0.23 至 0.84 kg P ha-1，其中颗粒 P (PP) 为 0.21 至 0.80 kg P ha-1。此外，在五种处理中，PP 损失占 TP 损失负荷的 92-96%。与 NPK 处理相比，有机改良剂的应用显着降低了 TN 损失，平均 85% 通过地表流动和 117% 通过内流。与 NPK 处理相比，有机改良剂的应用还显着减少了 TP 损失，通过地表漫流减少了 162%，通过内流减少了 90%。本研究表明，矿物肥料与有机肥或有机肥的结合可以缓解长江上游坡地农田水文氮、磷的流失。