The factor altering arbuscular mycorrhizal fungal effect on soil N2O emission is not quite clear: a meta-analysis

Abstract The control of soil nitrous dioxide (N2O) emission is of great importance to deal with climate change. We conducted a meta-analysis to quantify the potential effect of biotic and abiotic factors possibly altering the role of (AM) fungi in reducing soil N2O emission directly and indirectly via NH3 emission in natural and managed ecosystems. Our dataset was built based on 21 studies in both English (15 studies) and Chinese language (5 studies), including experiment-, plant-, AMF-, nutrient- and soil-related moderator variables. We found that the AM fungi reduced soil N2O emission by 11% (overall effect) and this reduction was observed in 84% of all trials. This effect varied largely from 265% decrease to 345% increase. Due to data limitations, it was still unclear that how AM effect was manipulated by these biotic and abiotic factors. We observed that measurement times, P availability and micronutrient addition had a compounding effect. We improved the sensitivity analysis techniques to evaluate the disproportional influence of a single study. In conclusion, AM fungi had a potential role in reducing soil N2O emission and currently, the available data did not support a meta-analysis on factors manipulating this effect. We call for more lab and field research targeting how biotic and abiotic factors alter this AM fungal effect on soil N2O emission.