Biochar Additions Improve Soil Nutrient Availability and Biomass Production of Cyclocarya paliurus via Regulating Soil Bacterial Community and pH Value on the Acidic Soil

Abstract Cyclocarya paliurus plantations are established in the subtropical regions of China to harvest its leaves for tea production, pharmaceutical and nutraceutical ingredients, whereas a large amount of pruning residues are generated every two years during the management. From the perspective of sustainable development, the biochar derived from its pruning branches has a great application potential in the management of C. paliurus plantations. A pot experiment was conducted to evaluate the addition effects of wheel wingnut based-biochars pyrolyzed at three temperatures (300℃, 500℃ and 700℃) on soil microbial community, nutrient availability, and biomass production in C. paliurus seedlings. The addition of wheel wingnut based-biochar not only increased soil pH and nutrients, but also enhanced the contents of leaf nutrients and photosynthetic pigments as well as biomass production in the seedlings after treatment of 200-days. Biochar additions improved the soil bacterial richness but reduced the diversity and richness in fungal communities. The relative abundances of Myxococcota , Gemmatimonadota , Bacteroidota , Patescibacteria and Nitrospirota in the soil increased along with the biochar pyrolysis temperature, but the abundance of most fungal communities decreased in the soil treated with biochar pyrolyzed at 300℃ compared to the soil without biochar addition. Addition of wheel wingnut based-biochar pyrolyzed at 500℃ demonstrated the best performance in enhancing the contents of leaf nutrients and photosynthetic pigments, as well as biomass increments. Biochar additions improve soil nutrient availability and biomass production of C. paliurus primarily via modifying soil bacterial community and pH value, whereas the biochar pyrolyzed at 500 °C showed an optimal performance.