Vegetable soils under plastic shed are characterized by multiple cropping and extremely high rates of nitrogen (N) application, but the N use efficiency (NUE) is generally low and the rate of N loss is often high. The underlying mechanisms behind these N losses following long-term N fertilizer applications remain elusive. Here, a ¹⁵N tracing incubation study in conjunction with in-situ monitoring was performed to investigate the effects of different N fertilization regimes on gross N transformations, microbial abundance and N losses via NO₃⁻ leaching and N₂O emissions in a vegetable soil under plastic shed subjected to 14 years of repeated N fertilization. The field experiment comprised of six treatments: no N fertilization (control, CK), and applications of chicken manure (M), chemical N plus M (CM), CM plus straw (CMS), 42 % of chemical N plus chicken manure (RCM) and RCM plus straw (RCMS). The results showed that the total gross N mineralization rates were significantly higher in CMS, RCMS and M treatments than in CK, CM and RCM treatments. The total gross NH₄⁺ immobilization rates followed the order of CK > CM > CMS > M > RCM ≈ RCMS, indicating a decreasing NH₄⁺ immobilization rate after N application. Gross autotrophic nitrification rate was significantly enhanced by fertilizer application in the order: CK < CM < CMS ≈ RCM < M < RCMS, mainly due to both increased mineralization rates and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB). A significant negative relationship between gross rates of NH₄⁺ immobilization and autotrophic nitrification suggests that higher autotrophic nitrification decreased NH₄⁺ immobilization. Reduced chemical N input alleviated soil acidification, NO₃⁻ leaching and N₂O emissions. There were significant positive relationships between rates of chemical N input and N loss but no relationships between gross N transformation rates and tomato yields, NO₃⁻ leaching losses and N₂O emissions. Thus, soil N transformation rates do not reflect rate of fertilizer N losses in vegetable soil managed under plastic shed. We thus suggest that chemical N application rate could be reduced to decrease N losses while sustaining vegetable production.

塑料棚下的蔬菜土壤以多次种植和极高的氮（N）施用率为特征，但氮的利用效率（NUE）通常较低，氮的损失率通常较高。在长期施用氮肥后，这些氮素损失背后的潜在机制仍然难以捉摸。这里，¹⁵结合N种描绘孵育研究原位进行调查对总Ñ变换，微生物丰度和氮素损失不同氮肥制度通过NO的影响监测₃ ^-浸出和N ₂在塑料棚下的蔬菜土壤中，O排放经过14年的反复N施肥。田间试验包括六种处理方法：无氮肥（对照，CK）和施用鸡粪（M），化学氮加镁（CM），有机肥加稻草（CMS），化学氮加鸡肉的42％（ RCM）和RCM加秸秆（RCMS）。结果表明，CMS，RCMS和M处理的总N总矿化率显着高于CK，CM和RCM处理。NH ₄ ⁺的总固定率遵循CK> CM> CMS> M> RCM≈RCMS的顺序，表明NH ₄ ⁺降低施氮后的固定率。施用肥料的顺序显着提高了总自养硝化率：CK <CM <CMS≈RCM <M <RCMS，这主要是由于矿化速率提高以及氨氧化古细菌（AOA）和细菌（AOB）含量增加。NH ₄ ⁺固定化的总速率与自养硝化之间存在显着的负相关关系，表明较高的自养硝化作用会降低NH ₄ ⁺固定化。缓解土壤酸化减少化学N个输入，NO ₃ ^-浸出和N ₂O排放。有化学N个输入和N的损失率，但毛氮转化速率，NO之间和西红柿的产量没有关系之间显著正关系₃ ^-浸出损失和N _2个O排放。因此，土壤氮的转化率不能反映在塑料棚下管理的蔬菜土壤中肥料氮的损失率。因此，我们建议可以降低化学氮的施用量，以减少氮的损失，同时维持蔬菜的产量。