Plastic-shed vegetable cultivation is characterized by high nitrogen (N) application rates, frequent irrigation and multiple cropping, probably leading to different soil N transformation rates compared to open-field cultivation. However, how continuous cultivation of vegetables under plastic sheds affects soil N transformation rates and associated nitrous oxide (NO) emissions remains unclear. Here, a N-tracing experiment in combination with the qPCR technique was used to investigate the effects of conversion from conventional open-field cultivation to plastic-shed vegetable cultivation, as well as the age of this shift, on soil gross N transformation rates, NO emission pathways and associated microbial abundances. Five typical fields, including a wheat–maize rotation system field and four adjacent plastic-shed vegetable fields under cultivation for 2, 5, 12 and 20 years, were selected. Soil gross N mineralization rates increased significantly after two years after conversion from a wheat–maize rotation system to a plastic-shed vegetable system, and then decreased with an increase in plantation age, which could be attributed to decreased soil total phosphorus availability. Long-term vegetable plantation under plastic-shed decreased soil gross autotrophic nitrification rates significantly by decreasing ammonia-oxidizing bacteria abundance probably due to decreasing soil pH. Such decreased rates of autotrophic nitrification further led to decreased NO emissions under plastic-shed cultivation. Under long-term plastic-shed cultivation (>2 years), negligible gross nitrate-N (NO-N) immobilization rates were observed due to the preferential use of ammonium-N by soil microbes, which was probably responsible for rapid NO-N accumulation in soils. Overall, these results could be of help to elucidate the mechanisms of soil NO emission and NO-N accumulation in plastic-shed vegetable fields.

中文翻译：

---

塑料大棚蔬菜种植改变土壤总氮转化率和一氧化二氮生产途径


塑料大棚蔬菜栽培的特点是施氮量高、灌溉频繁、复种，可能导致土壤氮素转化率与露地栽培不同。然而，塑料棚下蔬菜的连续种植如何影响土壤氮转化率和相关的一氧化二氮（NO）排放仍不清楚。在此，采用氮追踪实验与qPCR技术相结合，研究了从传统露地种植到塑料大棚蔬菜种植的转变以及这种转变的年龄对土壤总氮转化率的影响， NO 排放途径和相关微生物丰度。选取了5个典型田地，包括小麦-玉米轮作制田和相邻的4个种植2年、5年、12年和20年的塑料大棚菜地。从小麦-玉米轮作系统转为大棚蔬菜系统两年后，土壤总氮矿化率显着增加，然后随着种植年龄的增加而下降，这可能是由于土壤总磷有效性的下降。塑料大棚下的长期蔬菜种植园通过降低氨氧化细菌丰度而显着降低了土壤总自养硝化率，这可能是由于土壤pH值降低所致。自养硝化速率的降低进一步导致塑料大棚种植中 NO 排放量的减少。在长期塑料棚栽培（>2年）下，由于土壤微生物优先利用铵态氮，观察到可忽略不计的总硝酸盐-N（NO-N）固定率，这可能是快速NO-N的原因在土壤中的积累。 总体而言，这些结果有助于阐明塑料大棚菜地土壤NO排放和NO-N积累的机制。