Methane is the second most important greenhouse gas, and soils in arid region can oxidise large amounts of atmospheric methane, thereby contributing to mitigating climate warming. Elevating input of atmospheric nitrogen (N) and precipitation change significantly affect the strength of methane sink (uptake from the atmosphere), but this is still unclear in the desert steppe. Therefore, a field simulation N input (Nip) control experiment with a wet year (2019) and a dry year (2021) was done to elucidate the impact of Nip on methane sink in a typical desert steppe of Eurasia. The result showed that this desert steppe was a net sink of atmospheric methane with annaul uptake rate of 3.88 kg CH4 ha−1. And found that methane uptake was much lower in a wet year (33.9 ± 1.6 μg C m−2 h−1, 2019) than that in a dry year (46.9 ± 3.1 μg C m−2 h−1, 2021), which was mainly mediated by soil water-filled pore space. The effect of Nip on methane uptake was varied, both promoting (0.4 % – 1317%) and inhibiting (0.5% – 270.5%). And the inconsistent response of methane uptake was observed to Nip in a wet and a dry year: the methane uptake was decreased significantly with the increase of Nip rate in a wet year (p < 0.05); however, Nip did not significantly affect methane uptake overall in a dry year (p > 0.05). This may attribute to the inhibitory effect of Nip on methane uptake depended on soil moisture (p < 0.01). The abundance ratio of pmoA to mcrA gene was identified as the most significant influencing factors of methane uptake rather than soil inorganic N (NH4+-N or NO3−-N) content. Furthermore, soil moisture had an important indirect effect on methane uptake, mainly through influncing the abundance ratio of pmoA to mcrA gene. Overall, we suggest that the role of soil water-filled pore space and the abundance ratio of pmoA to mcrA gene should be considered when developing biochemical models of methane uptake in arid areas.

中文翻译：

---

氮输入对温带荒漠草原湿年和旱年甲烷吸收的影响


甲烷是第二重要的温室气体，干旱地区的土壤可以氧化大量的大气甲烷，从而有助于缓解气候变暖。大气氮 （N） 输入的增加和降水变化显着影响甲烷汇（从大气中吸收）的强度，但在荒漠草原中这一点仍不清楚。因此，在欧亚大陆典型荒漠草原上，开展了丰水年（2019 年）和枯水年（2021 年）的现场模拟氮输入 （Nip） 控制试验，以阐明 Nip 对甲烷汇的影响。结果表明，该荒漠草原是大气甲烷的净汇，年吸收率为 3.88 kg CH4 ha−1。并发现丰水年（33.9 ± 1.6 μg C m-2 h-1,2019 年）的甲烷吸收量远低于枯水年（46.9 ± 3.1 μg C m-2 h-1,2021 年），这主要由土壤充满水的孔隙空间介导。Nip 对甲烷吸收的影响是多种多样的，既促进 （0.4 % – 1317%） 又抑制 （0.5% – 270.5%）。在丰水年和旱年观察到甲烷吸收对 Nip 的不一致响应：在丰水年，甲烷吸收随着 Nip 速率的增加而显著降低 （p < 0.05）;然而，Nip 在干旱年份对甲烷的总体吸收没有显着影响 （p > 0.05）。这可能归因于 Nip 对甲烷吸收的抑制作用取决于土壤湿度 （p < 0.01）。pmoA 与 mcrA 基因的丰度比被确定为影响甲烷吸收的最显著影响因素，而不是土壤无机 N （NH4+-N 或 NO3−-N） 含量。此外，土壤水分对甲烷吸收具有重要的间接影响，主要通过影响 pmoA 与 mcrA 基因的丰度比。 总的来说，我们建议在开发干旱地区甲烷吸收的生化模型时，应考虑土壤充满水的孔隙空间的作用以及 pmoA 与 mcrA 基因的丰度比。