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

Calcium carbonate(CaCO_3) application is widely used to ameliorate soil acidification. To counteract soil and bacterial community response to CaCO_3 application in an acidic paddy soil in southern China, a field experiment was conducted with four different dosages of CaCO_3 addition, 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 CaCO_3 addition, and 7.5 tons/ha addition increased soil p H to neutral condition. Moderate dose of CaCO_3 application(4.5 tons/ha) significantly increased soil dissolved organic carbon(DOC) and dissolved organic nitrogen(DON) content, enhanced soil respiration, while the excessive CaCO_3 application(7.5 tons/ha) decreased these soil properties. High-throughput sequencing results illustrated that moderate dose of CaCO_3 application 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 CaCO_3 additions to acid paddy soil in southern China could have positive effects on soil properties and bacterial community.