Microbial response to CaCO3 application in an acid soil in southern China

Calcium carbonate(CaCO3) application is widely used to ameliorate soil acidification. To counteract soil and bacterial community response to CaCO3application in an acidic paddy soil in southern China, a field experiment was conducted with four different dosages of CaCO3addition, 0, 2.25, 4.5 and 7.5 tons/ha, respectively. After one seasonal growth of rice, soil physicochemical properties, soil respiration and bacterial communities were investigated. Results showed that soil p H increased accordingly with increasing dose of CaCO3addition, and 7.5 tons/ha addition increased soil p H to neutral condition. Moderate dose of CaCO3application(4.5 tons/ha) significantly increased soil dissolved organic carbon(DOC) and dissolved organic nitrogen(DON) content, enhanced soil respiration, while the excessive CaCO3application(7.5 tons/ha) decreased these soil properties. High-throughput sequencing results illustrated that moderate dose of CaCO3application increased the richness and alpha diversity of soil bacterial community. Compared with control, the relative abundance of Anaerolineaceae family belonging to Chloroflexi phylum increased by 38.7%, 35.4% and 24.5% under 2.25, 4.5 and 7.5 tons/ha treatments, respectively.Redundancy analysis(RDA) showed that soil p H was the most important factor shaping soil bacterial community. The results of this study suggest that proper dose of CaCO3additions to acid paddy soil in southern China could have positive effects on soil properties and bacterial community.