In recent years, Poyang Lake has been affected by severe agricultural non-point source (NPS) pollution, a global water pollution problem. The most recognized and effective control measure for agricultural NPS pollution is the strategic selection and placement of best management practices (BMPs) for critical source areas (CSAs). The present study employed the Soil and Water Assessment Tool (SWAT) model to identify CSAs and evaluate the effectiveness of different BMPs in reducing agricultural NPS pollutants in the typical sub-watersheds of the Poyang Lake watershed. The model performed well and satisfactorily in simulating the streamflow and sediment yield at the outlet of the Zhuxi River watershed. The results indicated that urbanization-oriented development strategies and the Grain for Green program (returning the grain plots to forestry) had certain effects on the land-use structure. The proportion of cropland in the study area decreased from 61.45% (2010) to 7.48% (2018) in response to the Grain for Green program, which was mainly converted to forest land (58.7%) and settlements (36.8%). Land-use type changes alter the occurrence of runoff and sediment, which further affect the nitrogen (N) and phosphorus (P) loads since sediment load intensity is a key factor affecting the P load intensity. Vegetation buffer strips (VBSs) proved the most effective BMPs for NPS pollutant reduction, and the cost of 5-m VBSs proved the lowest. The effectiveness of each BMP in reducing N/P load ranked as follows: VBS > grassed river channels (GRC) > 20% fertilizer reduction (FR20) > no-tillage (NT) > 10% fertilizer reduction (FR10). All combined BMPs had higher N and P removal efficiencies than the individual measures. We recommend combining FR20 and VBS-5m or NT and VBS-5m, which could achieve nearly 60% pollutant removal. Depending on the site conditions, the choice between FR20+VBS and NT + VBS is flexible for targeted implementation. Our findings may contribute to the effective implementation of BMPs in the Poyang Lake watershed and provide theoretical support and practical guidance for agricultural authorities to perform and direct agricultural NPS pollution prevention and control.

近年来，鄱阳湖受到严重的农业面源（NPS）污染的影响，这是一个全球性的水污染问题。最公认和最有效的农业 NPS 污染控制措施是关键源区 (CSA) 的最佳管理实践 (BMP) 的战略选择和部署。本研究采用土壤和水评估工具 (SWAT) 模型来识别 CSA，并评估不同 BMP 在减少鄱阳湖流域典型子流域农业 NPS 污染物方面的有效性。该模型在模拟竹溪河流域出口的径流量和输沙量方面表现良好，令人满意。结果表明，以城镇化为导向的发展战略和退耕还林计划（退粮还林）对土地利用结构有一定的影响。研究区耕地比例从61.45%（2010年）下降到7.48%（2018年），响应退耕还林计划，主要转化为林地（58.7%）和居民点（36.8%）。土地利用类型的变化改变了径流和泥沙的发生，这进一步影响了氮 (N) 和磷 (P) 负荷，因为泥沙负荷强度是影响磷负荷强度的关键因素。植被缓冲带 (VBS) 被证明是减少 NPS 污染物最有效的 BMP，而 5 米 VBS 的成本被证明是最低的。各 BMP 在降低 N/P 负荷方面的有效性排序如下：VBS > 草地河道 (GRC) > 20%减肥（FR20）>免耕（NT）>10%减肥（FR10）。所有结合的 BMP 比单独的措施具有更高的 N 和 P 去除效率。我们推荐FR20与VBS-5m或NT与VBS-5m组合使用，可达到近60%的污染物去除率。根据现场情况灵活选择FR20+VBS和NT+VBS，针对性实施。我们的研究结果可能有助于在鄱阳湖流域有效实施 BMP，并为农业主管部门开展和指导农业 NPS 污染防治提供理论支持和实践指导。我们推荐FR20与VBS-5m或NT与VBS-5m组合使用，可达到近60%的污染物去除率。根据现场情况灵活选择FR20+VBS和NT+VBS，针对性实施。我们的研究结果可能有助于在鄱阳湖流域有效实施 BMP，并为农业主管部门开展和指导农业 NPS 污染防治提供理论支持和实践指导。我们推荐FR20与VBS-5m或NT与VBS-5m组合使用，可达到近60%的污染物去除率。根据现场情况灵活选择FR20+VBS和NT+VBS，针对性实施。我们的研究结果可能有助于在鄱阳湖流域有效实施 BMP，并为农业主管部门开展和指导农业 NPS 污染防治提供理论支持和实践指导。