Organic management improves soil multifunctionality by enhancing soil quality and enriching key microbes in tea plantation

Intensive fertilization leads to soil acidification and nutrient imbalance in tea plantations. Organic management can improve soil structure, promote soil microbial activity and metabolism, and conducive to sustainable development of tea cultivation. However, our understanding of how long-term organic management affects soil quality index (SQI), soil multifunctionality (SMF), and microbial composition in tea plantations at different soil layers remains limited. Here, the enzyme activities, microbial communities, SQI and SMF in the topsoil (0–20 cm) and subsoil (20–40 cm) of tea plantations with conventional (CM) and organic (OM) managements for 20 years history were investigated. Results showed that compared to CM, OM significantly increased soil total nutrients, available nutrients, and enzyme activities (especially in the topsoil) in three tea plantations. In addition, OM increased SQI and SMF by 14.0 %–41.3 % and 143.6 %–262.9 % in the topsoil and 12.2 %–22.2 % and 37.2 %–63.2 % in the subsoil, respectively. OM significantly increased relative abundance of key bacteria and fungi involved in nutrient cycling, including Sphingomonas, Pseudomonas, Devosia, Nocardioides and Oidiodendron. Structural equation model analysis found that OM improved SMF by driving key bacteria and fungi species induced by higher total and available nutrients and enhancing SQI in the topsoil, while improved SMF only by driving key bacteria species and enhancing SQI in the subsoil. Overall, our results highlight that organic management can improve SMF by enhancing SQI and enriching key microbial species in tea plantation soils, and these findings provide new perspective for adjustment of agricultural managements in tea plantation.