Abstract: The indoor constant temperature culture method was adopted, and the 40-year-old tea garden soil applied with biochar-based fertilizer (BF) and without biochar-based fertilizer (CK) were selected as the research objects. Three different temperature scenarios were set at 15℃, 25℃ and 35℃, and the soil organic carbon (SOC) mineralization characteristics were continuously monitored and the temperature sensitivity of SOC mineralization was analyzed. It will provide reference for evaluating carbon sequestration emission reduction and obstacle reduction in aged tea gardens. The results showed that: (1) biochar-based fertilizer increased the pH and SOC content of tea garden soil under the temperature variation. At 15℃, 25℃ and 35℃, compared with CK treatment，the soil pH of BF treatment increased by 0.45, 0.07 and 0.28, respectively. The SOC content of BF treatment increased by 22.19%, 16.65% and 25.50%, respectively. (2) Biochar-based fertilizer increased the SOC accumulative mineralization amount, mineralization potential (C_S) and soil respiration intensity in tea gardens under temperature change, showing a positive priming effect on SOC mineralization. At 15℃, 25℃ and 35℃, compared with CK treatment, the accumulated SOC mineralization amount of BF treatment increased by 15.61%, 46.51% and 36.89%, respectively. The C_S value of BF treatment first increased and then decreased with rising temperature. Compared with 15℃ and 35℃, the C_S value of BF treatment at 25℃ increased by 147.11% and 29.21% respectively. (3) Biochar-based fertilizer decreased the temperature sensitivity of SOC mineralization in tea gardens under increasing temperature. In the temperature range of 25−35℃, the Q₁₀ (temperature sensitivity of soil organic carbon mineralization) value of BF treatment decreased by 6.25% compared with CK treatment. The Q₁₀ value of BF treatment in the temperature range of 25−35℃ decreased by 25% compared with the Q₁₀ value in the temperature range of 15−25℃. The results indicated that the application of biochar-based fertilizer can effectively improve the physical and chemical properties of the 40-year-old tea garden soil, increase soil carbon sequestration, and improve the stability of the soil carbon pool in response to temperature changes in the tea garden. Biochar-based fertilizer is conducive to optimizing the sustainable production management of low-yield and aging tea gardens.

Key words: Soil organic carbon, Greenhouse effect, Temperature sensitivity, Aged tea garden, Biochar