The variation in organic carbon mineralization and its temperature sensitivity in soils after long-term planting of different tea varieties

Evaluating soil organic carbon (SOC) mineralization and its temperature sensitivity (Q10) is essential to under-stand SOC sequestration capacity. However, little is known about the changes in the SOC mineralization process in soils when planting different tea varieties. In the current study, we collected soil samples from a tea plantation planted with four tea varieties (Chuancha No. 3 (CC3), Chuanmu No. 217 (CM217), Chuannong Huangyazao (CN), and C. Sinensis 'Fuding Dabaicha' (FD)). SOC mineralization and Q10 were investigated through a 90-day labo-ratory incubation experiment. The results demonstrated that both SOC mineralization and Q10 were variable among the soils after planting different tea varieties. Overall, CM217 soil had the highest cumulative mineral-ization amount (Cm), mineralization rate of SOC (Cr), potentially mineralizable carbon (C0), and the proportion of C0 in SOC (C0/SOC) at each incubation temperature, and FD soil had the lowest C0 and C0/SOC. These results indicated that CM217 and FD soil had the lowest and highest SOC sequestration capacity, respectively. This difference was explained by varied SOC stability (SI), which was further dominated by the SOC composition and aggregate distribution. FD soil showed the highest aggregate stabilization index (mean weight diameter, MWD) in both soil layers, accumulated the greatest recalcitrant organic carbon (ROC) and further contributed the highest sequestration capacity. In contrast, the lowest SI of CM217 soil reflected a low SOC sequestration ca-pacity, which would be detrimental to long-term SOC storage and ultimately explained the lowest SOC stock. In addition, the variations in Q10 among the soils planted with different tea varieties were explained by the different mechanisms in the topsoil and subsoil. The varied Q10 in topsoil and subsoil was predominantly explained by semi-labile organic carbon (LOCII) and ROC, respectively, and the contribution of aggregate protection to explain the varied Q10 in subsoil was greater than that in topsoil.