Abstract:In order to explore the effects of biochar combined with wood ash on soil carbon sequestration and microbial community, the changes of soil carbon sequestration, soil chemical properties, enzyme activities and microbial community compositions under biochar (B) and biochar combined with wood ash (B+W) treatments were studied through 118-day laboratory incubation. The results showed that both B and B+W treatments decreased the respiration rate and cumulative CO2-C respiration, and B + W treatment delayed the peak of CO2-C respiration. B and B+W treatments could increase the content of soil organic carbon and inorganic carbon. On day 118, the microbial biomass carbon of B and B + W treatments was higher than that of control, and that of B treatment was higher than that of B +W treatment, B+W treatment significantly increased the content of soil dissolved organic carbon and pH. B treatment increased the activities of β-1,4-glucosidase, the activities of β-1,4-xylosidase, β-1,4-glucosidase in B+W treatment were decreased by 38.4%, 15.3%, and the activity of invertase was increased by 61.4% respectively, as compared to control. B treatment had no significant effect on bacterial richness and diversity, but decreased Chao1 and Ace index of fungi; B+W treatment decreased the bacterial richness and diversity, but restored the fungal Chao1 and Ace index, and significantly increased Shannon index. On day 118, B treatment increased the relative abundance of Actinomycetes and decreased the relative abundance of Ascomycetes, B+W treatment increased the relative abundance of Chloroflexi and Basidiomycota, but decreased the relative abundance of Bacteroidetes. Redundancy analysis showed that biochar and biochar combined with wood ash affected soil microbial community by changing the soil chemical properties, soil organic carbon and pH were the most significant soil factors affecting bacterial and fungal community structure, respectively, B+W treatment showed better performance in reducing carbon mineralization in calcareous soils and maintaining the stability of the fungal community.