Soil organic carbon stock in China’s tea plantations and their great potential of carbon sequestration

China is the biggest tea producer in the world, and soils in the tea plantations play important roles in the carbon cycle, and regional and national carbon neutrality. The knowledge regarding the variation and the key drivers of soil organic carbon (SOC) stock in tea plantations could provide a scientific basis for assessing the potential of regional and national carbon sequestration and neutrality. This is also helpful for the sustainable management of tea plantations. However, little information is available on soil organic carbon (SOC) stock and influential factors in tea plantations. Thereby, SOC density (SOCD) and stock were estimated based on 1723 datasets collected from 322 published studies. Subsequent estimations reveal that the total SOC stock in China’s tea plantations is 207.13 Tg with 124.58 Tg SOC stored in top soil layer (0–20 cm), and the average SOCD is 59.17 Mg ha−1 ranging from 0.9 Mg ha−1 to 589.54 Mg ha−1. The SOCD showed a significant three-dimension zonal pattern and was significantly influenced by managerial practices. Tea plantations managed in ecological ways and/or with long stand age even showed higher SOCD than that in neighbored forests. The lower average but wide range of SOCD in tea plantations indicates their great potential in carbon sequestration. This makes tea plantations critically important in regional and national carbon accounting and carbon neutrality, and cannot be ignored in future research and policymaking initiatives.