Soil texture is an easily overlooked factor affecting the temperature sensitivity of NO emissions.

As a potent greenhouse gas, soil nitrous oxide (NO) is strongly stimulated by rising temperature, triggering a positive feedback effect of global warming. However, its temperature sensitivity varies greatly among soils with different physical and chemical characteristics, while associated mechanisms remain unknown. Here we performed a meta-analysis of the effect of warming on NO emission and found distinctions in the response of NO to temperature increase in soils with different textures. Then, we conducted an incubation experiment on 11 arable soils with varying textures sampled across China. The results show that the temperature sensitivity of NO emissions was lower as soil texture became more clayey and was consistent with the outcome of meta-analysis. Further analysis was conducted by classifying the soils into clay and loam subgroups. As shown in the clay soil subgroup, NO emission was significantly correlated with both inorganic nitrogen contents and potential denitrification and nitrification activities. Correlation analysis and partial least square (PLS) path model revealed that temperature mediated NO emission by regulating nosZ gene abundance indirectly. In loam soils, however, the indirect effect of temperature on NO production was achieved mainly through nirS gene abundance. Additionally, soil DON content strongly correlated with NO emission in both subgroups and affected NO emissions by influencing the abundance of denitrifiers under warming conditions. Our findings suggest that (i) soil texture was an important factor affecting temperature sensitivity of NO emission and (ii) variable efficacy of warming in soil NO production might originate from the enriching DON and nitrate content and its different indirect effects on nirS- or nosZ-type denitrifiers.

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