Mollisol soil is probably the most fertile soil for agricultural usage.Recent models predict that global warming caused carbon loss,which have important implications in primary productivity and ecosystem stability.Fertilizer usage can potentially change soil carbon by providing positive or negative feedbacks,leading to uncertainty in outcome.To address it,we conducted an experiment to simulate climate changes by transplanting Mollisol soil to two warmed sites(NC and NS,12.2 and 16.8 oC higher in temperature,respectively)in China,and examined fertilization effects on maize crops.Soil transplant caused loss in soil SOM,TN and TP,which were higher in NS than NC.Bacterial and fungal biomass and compositions were also altered.Fertilization appeared to induce priming effects at the NS site by increasing relative abundance of genes associated with recalcitrant carbon degradation and decreasing those associated with labile carbon degradation.Such changes were not observed at the NC site.Fungi played a dominant role in degrading recalcitrant carbon,thus fungi biomass and composition were significantly changed at NS sites,whereas bacterial composition remained unchanged.In contrast,fertilization barely changed soil nitrogen components and microbial genes associated with nitrogen cycling.Based on those findings,we predict that agricultural fertilizer administration exacerbated carbon loss in Mollisol under the global warming scenario by degrading recalcitrant carbon,raising an important concern since Mollisol is widely distributed in Europe,Asia and American continents.