Nitrous oxide (N₂O) is a potent greenhouse gas that is released from agricultural ecosystems where nitrogen fertilizers are poorly used and contributes to global climate warming. Large nitrogen fertilizer inputs in summer maize fields on the North China Plain (NCP) lead to large N₂O emissions. N₂O emissions can be mitigated using 3,4‐dimethylpyrazole phosphate (DMPP), but the efficiency and microbial mechanisms of this mitigation at different nitrogen rates remain poorly understood. To evaluate the efficiency of N₂O emission mitigation by DMPP at different nitrogen rates and to explore its mechanisms at the microbial level, we monitored the dynamic changes in mineral and N₂O fluxes and analysed the abundance and community structure of ammonia oxidizers. We found that DMPP significantly inhibited the oxidation of ammonium (NH₄⁺) to nitrate (NO₃⁻) and thus maintained NH₄⁺ concentrations but decreased the peak value of NO₃⁻ concentrations. Total N₂O emissions were increased by 6.5‐fold, 13.2‐fold and 26.7‐fold in fields with 112.5 kg N ha⁻¹, 225 kg N ha⁻¹ and 337.5 kg N ha⁻¹, respectively, compared with fields with no nitrogen applied. Nitrogen increased the abundance of ammonia‐oxidizing bacteria (AOB) and decreased that of ammonia‐oxidizing archaea (AOA), whereas DMPP exhibited the opposite effects. Therefore, AOB could be the dominant N₂O emission contributors in nitrogen‐treated soils. Sequencing results suggested that all AOB belong to the Nitrosospira and Nitrosomonas nitrosa groups, and all AOA fell within the Nitrososphaera group. In both AOB and AOA communities, changes in the second‐largest cluster after the application of nitrogen fertilizer and DMPP were more pronounced than those in the largest cluster. The potential functional clusters of AOB and AOA were Nitrosospira cluster 3b and Nitrososphaera cluster 4.1, respectively. This study showed that nitrogen and DMPP both affected the abundance and structure of ammonia‐oxidizer communities, which may contribute to the variations in N₂O emissions from croplands.

中文翻译：

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硝化抑制剂3,4-二甲基吡唑磷酸酯（DMPP）通过改变华北平原小麦-玉米轮作中的土壤微生物群落来减少N2O排放

一氧化二氮（N ₂ O）是从农业生态系统中释放的有力温室气体，在这些农业生态系统中，氮肥的使用不足，并助长了全球气候变暖。华北平原夏季玉米田大量投入氮肥导致大量N ₂ O排放。使用3,4-二甲基吡唑磷酸酯（DMPP）可以减轻N ₂ O的排放，但是在不同氮含量下这种缓解的效率和微生物机理仍然知之甚少。为了评估在不同氮含量下DMPP缓解N ₂ O排放的效率并探讨其在微生物水平上的机理，我们监测了矿物质和N ₂的动态变化。O通量，并分析了氨氧化剂的丰度和群落结构。我们发现，DMPP显著抑制铵（NH氧化₄ ⁺）以硝酸盐（NO ₃ ^- ），并且因此维持NH _4个⁺浓度反而下降NO的峰值₃ ^-的浓度。总共N _2个O排放分别增加了6.5倍，13.2倍，并与112.5千克Ñ公顷字段26.7倍^-1 225公斤氮公顷^-1和337.5千克Ñ公顷^-1分别与未施氮的田地相比。氮增加了氨氧化细菌（AOB）的含量，降低了氨氧化古细菌（AOA）的含量，而DMPP则表现出相反的效果。因此，AOB可能是氮处理土壤中主要的N ₂ O排放贡献者。测序结果表明，所有AOB属于Nitrosospira和亚硝化nitrosa组，所有的AOA内下跌Nitrososphaera组。在AOB和AOA社区中，施用氮肥和DMPP之后第二大集群的变化比最大集群的变化更为明显。AOB和AOA的潜在功能簇是亚硝基螺菌簇3b和亚硝化球簇4.1。这项研究表明，氮和DMPP均会影响氨氧化器群落的丰度和结构，这可能会导致农田中N ₂ O排放量的变化。