Effects of different plant-derived biochars on physicochemical properties and microbial communities in tea plantation soil

Long-term over-fertilization has caused increased soil acidification and nutrient loss in tea plantations. The benefits of biochar in alleviating soil acidification have been established, yet little is known specifically about the performance of different plant-derived biochar types in tea plantation soils. An incubation experiment was conducted to investigate the effects of three biochar types (corn stover, reed, and coconut shell), and three application levels (0%, 0.5%, and 1.0%) on soil pH, nutrient content, and microbial community in tea plantation soils. The findings demonstrated that the application of coconut shell biochar resulted in a significant increase in soil pH and an enhancement of catalase and urease activities, particularly at higher application rates. Furthermore, the application of biochar enhanced the soil organic matter and available phosphorus content, with coconut shell biochar showing the most pronounced effects. Microbial community analysis revealed that biochars increased bacterial diversity and altered the composition of the fungal community. The application of biochars reduced the relative abundance of the unclassified genus within the Acidobacteria phylum, and 1.0% coconut shell biochar significantly increased the abundance of the bacterial phyla Actinobacteriota and Gemmatimonadota. These findings suggest that biochar, especially coconut shell-derived biochar, could effectively ameliorate soil acidity, enhance nutrient availability, and improve microbial diversity in tea plantations. The study provides a theoretical basis for the informed application of biochars in tea plantations in the future.