In Mediterranean regions, the accumulation of nitrogenous substrates in soil during summer fallow period has been linked to pulses of N₂O emissions upon soil rewetting. Although the mechanisms of N₂O emission after soil rewetting have been previously studied, potential mitigation of agronomic practices on N₂O pulses is still poorly understood. We studied the N₂O emissions after rewetting of degraded soils managed by no-tillage (NT) and conventional tillage (CT), both with or without lime application under laboratory conditions. The soil was rewetted to 50 and 100% of field capacity (FC) and the N₂O fluxes, size, structure and gene transcription of the microbial communities involved in the N₂O emissions were evaluated. Liming reduced the cumulative N₂O emission by more than 70 and 65% respect to the unamended soil after soil rewetting to 50% and 100% of FC, respectively, whereas no significant effect of tillage on N₂O emission was observed. Liming strongly influenced the size and structure of ammonia oxidizing bacteria (AOB) and denitrifier communities, increased the transcription of the nirK after soil rewetting, while transcription of genes encoding nitrification enzymes was undetectable. Tillage slightly affected the nitrifier and denitrifier communities, with CT increasing the size of nosZ community. The results indicated that the N₂O pulse after soil rewetting was caused by denitrification rather than nitrification. In addition, the increase of nirK transcription suggested that the mitigation of N₂O emissions observed in limed soils was due to changes in the denitrification process, possibly with a higher or more efficient reduction of N₂O to N₂. This study showed the potentials of NT and liming management to mitigate the N₂O emission from degraded Mediterranean soils after soil rewetting due to changes in the efficiency of the denitrification process. Our results also showed the usefulness of coupling determinations of gas emission, microbial community structure and gene transcription to clarify the underlying mechanisms of N₂O emissions from soil.

在地中海地区，夏季休耕期土壤中的氮质底物积累与土壤重新湿润时产生的N ₂ O排放脉冲有关。尽管先前已经研究了土壤重新湿润后N ₂ O排放的机理，但对农艺措施对N ₂ O脉冲的潜在缓解作用仍知之甚少。我们研究了在实验室条件下是否使用石灰的情况下，通过免耕（NT）和常规耕作（CT）对退化土壤进行重新湿润后的N ₂ O排放量。将土壤重新湿润至田间持水量（FC）的50％和100％，以及N ₂ O的通量，大小，结构和参与N ₂的微生物群落的基因转录评估了O排放。翻耕后，石灰对未改良土壤的累积N ₂ O排放量分别减少了70％和65％以上，分别为FC的50％和100％，而耕作对N ₂ O排放量没有显着影响。石灰强烈影响氨氧化细菌（AOB）和反硝化菌群落的大小和结构，增加土壤重新湿润后nirK的转录，而编码硝化酶的基因的转录则无法检测到。耕作对硝化器和反硝化器群落有轻微影响，而CT增加了nosZ群落的大小。结果表明，N ₂土壤重新湿润后的O脉冲是由反硝化而不是硝化作用引起的。此外，增加nirK转录建议N的缓解₂ O排放量在土壤浸灰观察是由于在反硝化过程中的变化，可能以更高的或更有效地降低N个₂ O与N ₂。这项研究表明，由于反硝化过程效率的变化，在土壤重新湿润后，NT和石灰管理可以减轻退化的地中海土壤中N ₂ O的排放。我们的研究结果还显示了气体排放，微生物群落结构和基因转录的耦合测定对阐明氮的潜在机制的有用性。_2个从土壤O排放。