Farmland surface soil mulching with plastic film is extensively used to enhance agricultural productivity in the Loess Plateau (LP). However, the effect of mulching on the key processes that dominate soil nitrogen dynamics is rarely assessed quantitatively. We quantified the responses of agroecosystem nitrogen cycling to plastic mulching using a comprehensive database drawn from mulching experiments in the LP. Our results indicated that through increasing the soil mineral and dissolved organic nitrogen concentrations, plastic mulching significantly enhanced the soil nitrogen availability by 36.6% at the regional scale, compared with traditional nonmulching. Mulching pattern, nitrogen application, and soil type were found to be the most significant drivers in determining nitrogen availability. Furthermore, nitrogen gaseous releases and hydrological leaching were significantly reduced by 7.0% and 9.4%, respectively, under plastic mulching, which led to an insignificant change in the soil total nitrogen pool. Nitrogen input level and soil organic carbon appeared to be the most important factors influencing soil nitrogen losses. Critically, along with increased root residue inputs to soil and improved water thermal conditions under mulching, soil microbial activity was increased significantly. This was indicated by enhanced microbial biomass nitrogen and soil nitrogen‐related extracellular enzyme activity and was driven by nitrogen input, mulching duration, and soil carbon status. We generalize that in the rain‐fed agroecosystems of the LP, plastic mulch will have little impact on nitrogen pool size, largely due to reduced gaseous and hydrological nitrogen losses and increased crop‐sourced nitrogen inputs, but will strongly stimulate microbial growth, metabolism, and activities, which consequently will speed up biogeochemical cycles of soil nutrients.

中文翻译：

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黄土高原雨养农业生态系统中塑料覆盖物对土壤氮库，循环和通量的区域效应定量

黄土高原（LP）广泛使用农田地膜覆盖塑料膜来提高农业生产力。但是，覆盖对影响土壤氮动力学的关键过程的影响很少进行定量评估。我们使用从LP覆盖试验中获得的综合数据库，对农业生态系统氮循环对塑料覆盖的响应进行了量化。我们的结果表明，与传统的非覆盖相比，通过覆盖增加土壤矿物质和溶解性有机氮的浓度，塑料覆盖显着提高了区域尺度上土壤氮的利用率达36.6％。发现覆盖模式，施氮和土壤类型是决定氮有效性的最重要驱动因素。此外，在塑料覆盖下，氮的气体释放和水文淋滤分别显着减少了7.0％和9.4％，这导致土壤总氮库的变化很小。氮素输入量和土壤有机碳似乎是影响土壤氮素流失的最重要因素。至关重要的是，随着根残留物输入土壤的增加以及覆盖条件下水热条件的改善，土壤微生物活性显着提高。微生物生物量氮和土壤氮相关的细胞外酶活性增强表明了这一点，而氮输入，覆盖时间和土壤碳素状态则驱动了这一点。我们得出结论，在LP的雨养农业生态系统中，塑料覆盖物对氮库规模的影响很小，