Microbially mediated mechanisms underlie soil carbon accrual by conservation agriculture under decade-long warming

Increasing soil organic carbon (SOC) in croplands by switching from conventional to conservation management may be hampered by stimulated microbial decomposition under warming. This study investigates the interactive effects of agricultural management and warming on SOC persistence and underlying microbial mechanisms in a decade-long controlled experiment on a wheat-maize cropping system. Warming increased SOC content and accelerated fungal community temporal turnover under conservation agriculture (no tillage, chopped crop residue), but not under conventional agriculture (annual tillage, crop residue removed). Microbial carbon use efficiency (CUE) and growth increased linearly over time, with stronger positive warming effects after 5 years under conservation agriculture. Structural equation models indicate that these increases arose from greater carbon inputs from the crops, indirectly controlling microbial CUE via changes in fungal communities. Fungal necromass increased significantly, emerging as the strongest predictor of SOC content. The results demonstrate how management and climatic factors interact to alter microbial community composition, physiology, and functions, impacting SOC formation and accrual in croplands.

Jing Tian, Jennifer A. J. Dungait, Ruixing Hou, Ye Deng, Iain P. Hartley, Yunfeng Yang, Yakov Kuzyakov, Fusuo Zhang, M. Francesca Cotrufo, Jizhong Zhou