Microbial Community of Subsoiling Have a Stronger Ability to Utilize Carbon Sources Across Aggregate Classes in an Anniversary Rotation

Purpose The goal of global carbon (C) neutralization has raised concerns about the potential of soil organic carbon (SOC) storage, particularly regarding the role of soil microbial activities across aggregate classes. Reasonable tillage methods drive microbial community within soil aggregates, so have a stronger ability to utilize carbon sources. However, simultaneously studying the effects of tillage methods through microbial activity, functional and structural diversity at the aggregate level is relatively rare, and seasonal changes in the ability to utilize carbon sources of microbial communities remain largely unknown. Methods Initial from 2002, a 14-year long-term tillage experiment started; then in 2016–2017, we tested the following tillage methods: no tillage (NT), rotary tillage (RT), subsoiling (ST) and conventional tillage (CT). Results Compared with CT, ST had the most significant promoting effect on microbial activity across aggregate classes, and microbial activity (ATP and SIR) decreased with the aggregate classes decreasing. ATP and SIR increased by 3.23 µmol·g − 1 and 15.94 µg CO 2 ·g − 1 ·d − 1 in winter wheat growth, and increased by 2.39 µmol·g − 1 and 31.16 µg CO 2 ·g − 1 ·d − 1 in summer maize growth. Microbial communities in aggregates under ST and NT had greater diversity and ability to utilize carbon sources compared with CT, and those function showed the order of 5 − 2 > 2-0.25 > 0.25–0.053 mm. The microbial activity and diversity were higher in summer maize growth. Conclusions Therefore, ST is a promising tillage method for enhancing the soil microbial activity and diversity. Our study provides a fundamental understanding for the utilization of carbon sources by microbial community whithin aggregate level and highlights the importance of reasonable tillage methods.