Fertilization managements mitigate microbial carbon and nitrogen limitations while preserving soil organic carbon in...

Enzymatic stoichiometry is increasingly employed in studies to infer microbial nutrient limitations, which can be attributed to soil microbes allocating more resources to extracellular enzyme production to obtain more strictly limited nutrients. However, it remains unclear how the capacity of enzymes involved in nutrient acquisition, and organic C (SOC) storage regulates microbial metabolism limitations in response to different fertilization strategies. In this study, we performed a meta-analysis of 42 published studies to investigate how soil enzymes and SOC shape microbial metabolic responses to diverse fertilization (i.e., organic, inorganic and combined fertilizers). The results showed that fertilization generally significantly increased SOC by 18.82 %, with variations likely linked to ecosystem types and fertilization strategies. We also found that optimal temperatures and precipitation can enhance microbial activity and SOC accumulation. Additionally, the increase in ratios of C-acquiring enzymes to phosphorus (P)-acquiring enzymes (EEA_C:P) by 12.77 % and nitrogen (N)-acquiring enzymes to P-acquiring enzymes (EEA_N:P) by 8.37 %, suggests that a relative increase in microbial limitations for C and N versus P. Moreover, organic fertilizer (OF) treatments exacerbated microbial C limitation, as evidenced by a significant increase in vector length (VL) by 9.12 %. Overall, our findings suggest that fertilization involving organic fertilizers mitigate microbial carbon and nitrogen limitations while preserving organic carbon in croplands versus grasslands, which is crucial for maintaining soil quality. This finding underscores the importance of microbial metabolism, as governed by enzyme stoichiometry, for understanding soil nutrient cycling and for optimizing fertilization strategies according to soil fertility across ecosystems.