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Improved knowledge of how tea planting age impacts the relationships of soil aggregates with microbial biomass and activity may help understand the mechanisms of improving soil organic matters (OM) sequestration in tea plantation ecosystem. In this study, soil samples (0-20 cm depth) were collected from tea plantations with various ages (8, 17, 25 and 43 years) in the southern Guangxi, China. Soil samples were split into > 2, 2-1, 1-0.25 and < 0.25 mm aggregates following an optimal moisture sieving procedure. Long-term tea planting was favorable to Corg and Nt accumulation in soil aggregates. However, soil aggregate-related microbial biomass (Cmic and Nmic contents) and activity (respiration rate) first increased and then decreased, and their levels were highest in the 17-year tea plantations. After 17 years of tea planting, the disintegration of > 2 mm fractions in soils might partially explain the decreases of microbial biomass and activity. Meanwhile, soil OM availability and soil acidification were also important drivers of the changes in soil microbial biomass and activity during tea planting. Hence, implementing a sustainable management scheme is critical to maintaining microbial community development after 17 years of tea planting, and thus favor nutrient cycling and energy flow in soils. [ABSTRACT FROM AUTHOR]