Objective The aims were to reveal the effects of biochar input on the soil bacterial community structure and diversity.

Method The biochar form straw and the maize-planted albic soil in the Sanjiang Plain were taken as the research object. Biochar was added based on 0% (CK), 1% (B1), 3% (B2) and 5% (B3) of the soil weight then soil samples were collected after 90 days of culture. The Illumina Miseq sequencing technology was used to analyze the effects of different biochar addition amounts and times on the bacterial community structure in the maize-planted soil in the Sanjiang Plain and reveal the regulation rule of biochar on the bacterial community structure in the farmland soil.

Result The results showed as follows: compared with CK, low-proportion addition (1%) significantly increased the diversity and richness of the soil bacterial community, while high-proportion addition (3%-5%) significantly decreased the diversity and richness of the soil bacterial community. The main dominant bacterial phyla under different biochar additions were Proteobacteria, Actinomyces, Acidobacteria and Chloromyces. However, with the increase in biochar concentration, the relative abundance of Proteobacteria and Actinobacteria in the soil gradually decreased, while the relative abundance of Acidobacteria and Chloromyces gradually increased, with KD4-96, Subgroup_6, Gemmatimonas, Haliangium, Bradyrhizobium as the dominant species., the relative abundances of KD4-96, Subgroup_6 and Gemmatimonas were significantly positively correlated with biochar (P < 0.05). While the relative abundances of Haliangium and Bradyrhizobium were significantly negatively correlated with biochar (P < 0.05). Redundancy analysis showed that soil bulk density, field water capacity, pH, organic matter, total nitrogen, total phosphorus and saturated volume water content changes were the main environmental factors influencing the soil bacterial community structure, and field water capacity and saturated volume water content significantly influenced soil bacterial abundance.

Conclusions The application of biochar can change soil properties and indirectly drive changes in the soil microbial community structure.