Flood irrigation and over fertilization lead to a large amount of nitrogen (N) leaching in conventional plastic shed vegetable production systems, resulting in low N use efficiency and huge environmental costs. Drip fertilization can significantly reduce N leaching by reducing irrigation and N application; however, the respective roles of each factor in reducing N leaching remain unknown. In this study, structural equation modeling was carried out to determine the direct and indirect relationships among factors related to N leaching in plastic shed tomato production across six consecutive growing seasons. Treatments were as follows: conventional flooding irrigation and fertilization (CIF); CIF + corn straw (CIF + C); CIF + wheat straw (CIF + W); drip irrigation and fertilization (DIF); DIF + corn straw (DIF + C); and DIF + wheat straw (DIF + W). The results showed that the most important contributing factor to N leaching in this study was water percolation, which is mainly controlled by irrigation amount. This suggests that irrigation amount has a greater effect than N input rate and straw addition. Compared to CIF, DIF significantly reduced N leaching by an average of 63.9% without compromising tomato yield, with significant increases of 52.9% and 28.1% in the water use efficiency (WUE) and partial factor productivity of applied N (PFP_N), respectively. Meanwhile, application of straw also resulted in a significant reduction in N leaching by reducing water percolation, with wheat straw having a greater effect than corn straw. Overall, excessive irrigation rather than N input was found to be the main cause of significant N leaching, highlighting the importance of optimal irrigation schemes. We therefore recommend precise drip irrigation and fertilization combined with straw addition for sustainable and environmentally-friendly plastic shed vegetable production.

洪水灌溉和过度施肥导致常规塑料棚蔬菜生产系统中大量的氮（N）浸出，导致氮利用效率低下和巨大的环境成本。滴灌施肥可以通过减少灌溉和施氮量来显着减少氮的淋失；然而，每个因素在减少氮淋失中的各自作用仍然未知。在这项研究中，进行了结构方程建模，以确定在连续六个生长季节中，塑料大棚番茄生产中与氮淋失相关的因素之间的直接和间接关系。处理方法如下：常规洪水灌溉和施肥；CIF +玉米秸秆（CIF + C）; CIF +麦秸（CIF + W）; 滴灌和施肥（DIF）；DIF +玉米秸秆（DIF + C）; 和DIF +麦秸（DIF + W）。结果表明，本研究中影响氮淋溶的最重要因素是渗水，渗水主要受灌溉量的控制。这表明灌溉量比氮输入速率和秸秆添加量具有更大的影响。与CIF相比，DIF显着减少了N浸出，平均降低了63.9％，而没有损害番茄的产量，水分利用效率（WUE）和部分施氮量（PFP）分别显着提高了52.9％和28.1％_N）。同时，秸秆的施用还通过减少水的渗透而显着减少了氮的浸出，其中小麦秸秆的作用比玉米秸秆的作用大。总体而言，发现大量灌溉而非氮输入是造成大量氮淋失的主要原因，突显了最佳灌溉方案的重要性。因此，我们建议精确滴灌和施肥结合秸秆添加，以实现可持续和环保的塑料棚蔬菜生产。