[Effects of Biochar Application on Bacterial Community Structure and Symbiotic Network Analysis in Acidic Purple...

As an organic soil amendment, biochar plays a significant role in ameliorating soil acidification and promoting microbial activity. Through field experiments, the impact of biochar on the composition and functions of bacterial communities in acidic purple soil were evaluated. Four treatments were established： no fertilizer （CK）, conventional fertilization （F）, chemical fertilizer combined with organic fertilizer （OF）, and chemical fertilizer combined with biochar （BF）. Using indoor analysis and Illumina MiSeq high-throughput sequencing technology, we analyzed the changes in soil physicochemical properties, bacterial community diversity, community composition, bacterial network, and functional predictions under different treatments over time. The results indicated that biochar treatment significantly increased soil pH and the content of available nutrients （such as alkali-hydrolyzable nitrogen, available phosphorus, and readily available potassium） and significantly enhanced the α and β diversity of bacterial communities, particularly in the second year （P < 0.05）. After two years of biochar and organic fertilizer application, the complexity and stability of the soil microbial network were significantly reduced, promoting microbial synergism. Functional predictions showed that the BF treatment significantly improved key bacterial functions such as organic matter degradation, energy production and conversion, and amino acid transport and metabolism, but these functional activities significantly weakened in the second year. Additionally, the application of biochar significantly increased the relative abundance of Paeniglutamicibacter and Rhodococcus, which play key roles in organic matter degradation and energy production. Overall, biochar not only improved soil physicochemical properties but also enhanced bacterial community functions and diversity, thereby improving soil health and ecosystem functions. However, its long-term effects require continuous attention and maintenance, providing scientific evidence for achieving sustainable agricultural development.