Global patterns of microbial metabolic regulation under conservation tillage and implications for soil carbon cycling

Conservation tillage is a pivotal agricultural strategy for climate change mitigation, primarily credited for enhancing soil organic carbon (SOC) sequestration. However, a comprehensive understanding of its effects on the underlying biological drivers, i.e., the soil microbial community and its metabolic functions, remains fragmented at the global scale. We synthesized global evidence on the effects of conservation tillage on soil microbial community structure, enzyme activities, and metabolic indicators (CUE, Q10, qCO₂, MQ, and CUE). Conservation tillage significantly increases microbial biomass and activities of carbon-, nitrogen-, and phosphorus-acquiring enzymes. Across studies, microbial CUE and MQ increase while qCO₂ decreases, indicating enhanced microbial growth efficiency and reduced carbon loss through respiration. Conservation tillage also moderates the temperature sensitivity of soil respiration, suggesting improved stability of soil carbon under climate warming. These effects are context-dependent and regulated by climate, soil properties, and management duration. Our synthesis demonstrates that conservation tillage promotes a microbial metabolic strategy favoring soil carbon retention and provides a mechanistic basis for evaluating management-induced changes in soil carbon sequestration potential.