Soil microbial nutrient limitations dominate biogeography of their carbon use efficiency

Aim: Qualifying the biogeographical patterns of soil microbial carbon use efficiency (CUE) are crucial for C model development to accurately predict soil C stocks and the C-climate feedback. Location: Northern China Major taxa studied: Microbial CUE Methods: We used the extracellular enzyme activities stoichiometry and metagenomic sequencing method to quantify the biogeographical patterns of microbial CUE and identify their drivers across northern China (a total of 279 soil samples, covering a wide range of geoclimatic patterns) Results: We found that the values of CUE originating from the cold and humid ecosystem were dramatically greater than that of the warm and dry ecosystem. Soil microbial nitrogen (N) and phosphorus (P) limitation inferring from exoenzymatic stoichiometry and metagenomics, particularly for N limitation involving denitrification-induced N loss, exhibited strong negative effects on CUE. Main conclusions: Our biogeography of soil microbial CUE highlights the importance of soil nutrients limitation to predicate soil C sinks in Chinese ecosystem, which has significant implications for future study and policy decisions in different ecosystem management.