Long-Term Liming Reduces the Emission and Temperature Sensitivity of N2o Via Altering Denitrification Functional Gene Ratio in Acidic Soil

Lime has been widely applied for ameliorating soil acidification, potentially improving soil fertility and crop production. However, the effects of long-term liming and its interaction with carbon (C) availability on the emission and temperature sensitivity (Q10) of N2O from acidic arable soils are not well understood. Here, the limed and unlimed acidic soils collected from long-term liming field trial, amended with and without glucose, were incubated at 15℃ and 25℃ to investigate the responses of the emission and Q10 of N2O and the underlying mechanisms. The results showed that long-term liming had no effect on N2O emissions in the absence of glucose. While after glucose addition, N2 O emissions were 13–28% lower in the limed relative to unlimed soils, indicating that the N2O mitigation via liming was largely limited by C availability. High temperature did not affect N2O emissions from the glucose absent soils, but greatly increased N2O emissions after glucose addition, with significantly lower Q10 of N2O in the limed (1.23) relative to unlimed soils (1.48). These results suggested that long-term liming could mitigate the positive effect of glucose addition on the Q10 of N2O. Long-term liming increased the abundances of N2O reductase genes ( nosZI and nosZII ) relative to nitrite reductase genes (nirK and nirS) due to elevated soil pH, thus resulting in significantly lower (nirK+nirS)/(nosZI+nosZII) ratio compared to the unlimed soil, particularly after glucose addition. N2O emission was strongly positively related to the nirK abundance, (nirK+nirS)/( nosZI+nosZII) ratio, and NO3− consumption after glucose addition, indicating that denitrification was mostly responsible for N2O emission. Concluding, long-term liming can potentially reduce N2O emission and its temperature sensitivity via decreased (nirK+nirS)/(nosZI+nosZII) ratio in acidic soils under adequate C availability