Effects of biochar amendment on bacterial and fungal communities in the reclaimed soil from a mining subsidence area

Biochar amendment of soil is well known to improve soil fertility and microbial function. However, little is known about the effect of biochar addition to reclaimed soil in coal mining subsidence area on microbial community. A plant soil cultivation experiment was conducted with wheat grown and four treatments were included: P and K fertilizer (CK); NPK inorganic fertilizer (NPK); NPK inorganic fertilizer and straw (NPKS); and NPK inorganic fertilizer and biochar (NPKB). The results indicated that biochar amendment significantly increased the concentrations of NH₄ ⁺-N, total N, and available P and K compared with the NPK. Biochar addition also significantly increased the grain yield and total biomass of wheat. Furthermore, biochar amendment treatment increased the absolute abundance and altered the community structure of soil bacteria and fungi in the reclaimed soil. Illumina MiSeq sequencing showed that the addition of biochar increased α-diversity of bacteria and relative abundances of Proteobacteria, Actinobacteria, and Bacteroidetes, whereas the relative abundance of Firmicutes were decreased by 61%. However, biochar addition did not change the relative abundance of dominant fungal phyla. Redundancy analysis (RDA) suggested that total N, available P, and K contents were the key factors correlated with changes in microbial community structure. Overall, our results suggest that biochar amendment in reclaimed soil in coal mine subsidence area could increase wheat yield and abundance and alter microbial community compositions.