Influence of biochar and biochar-based fertilizer on yield, quality of tea and microbial community in an acid tea orchard soil

Biochar combined with chemical fertilizer have been proven to be effective in improving soil fertility and crop yield. However, the effects of biochar-based fertilizer on yield, quality of tea and microbial community composition in tea orchard soil are unclear. To address this, four different treatments including CK (no fertilizer), B (biochar), F (chemical fertilizer), BF (biochar-based fertilizer) were performed in a tea orchard to explore the effects of different fertilizations on tea growth and the soil bacterial and fungal community. After one growing season, the BF increased the yield, 100-sproutweight and sprout density of tea by 39.2%, 26.6% and 10.7%, respectively, compared to CK. Amino acid content of F and BF, caffeine content of B, F and BF and the water extracts in BF were increased than those of CK. Soil bacterial and fungal diversity indices (chao1 and observed species) were generally higher under B than BF and F treatment. Cluster analysis revealed that bacterial and fungal community structures under BF treatment differed from those under CK, B and F treatment. The relative abundance of 10 key bacterial genera and 13 fungal genera were increased under BF treatment, including some plant beneficial microbes such as bacterial genera Rhodanobacter, Mizugakiibacter, Pedobacter, Sphingomonas and Devosia as well as fungal genera Rhodosporidiobolus, Chloridium, Amylocorticium, Clavulina, Inocybe and Mycofalcella. These genera were significantly positive correlated to yield and quality of tea. Redundancy analysis revealed that pH, total nitrogen and available potassium were the major properties shaping soil bacterial community, and dissolved organic carbon, exchangeable Ca, pH and total nitrogen were for fungal community. These results indicated that biochar-based fertilizer altered soil microbial community and enhanced some plant growth-promoting microbes, which were associated with the improvements of yield and quality of tea plants. Thus, the combination of biochar and chemical fertilizer is feasible for the improvements of tea growth and low nutrients acidic tea orchard soil.