The role of soil properties and temperature on soil organic carbon decomposition: Stronger influences than bacterial communities and pool‐specific responses to warming

Abstract Soil organic carbon (SOC) is the largest carbon pool in terrestrial ecosystems and is crucial for regulating climate change dynamics. Yet, the relationship between SOC's chemical structure and microbial community composition remains elusive, especially under varying temperature conditions. This study investigates soil samples from four distinct cropland sites. The samples were incubated at 0, 10, 20, 30 and 40°C for 200 days. High‐throughput sequencing technology and solid‐state 13 C nuclear magnetic resonance ( 13 C NMR) spectroscopy were employed in the analysis. Additionally, a data assimilation approach was applied to estimate parameters for three C pools (active, slow and passive) based on time‐series data. Results indicated that the Q 10 values of the C pools increased with resistance to decomposition and decreased as incubation temperature rose. SOC cumulative decomposition was positively correlated with alkyl C/O‐alkyl C ratio (A/O_A), reflecting the degree of SOC degradation. The response of the C pool Q 10 , chemical structure and bacterial community composition to temperature was site‐specific. Firmicutes and proteobacteria showed negative correlations with carbohydrates and positive correlations with aromatic C–O. Interestingly, the interaction between C functional groups and the bacterial community only affects changes in soil C within the active pool. Moreover, soil properties (C/N ratio and clay content) and mean annual temperature (MAT) are the main factors regulating active, slow and passive C pools, respectively. This study demonstrates that in agricultural soils, clay content and carbon quality have a more significant impact on SOC decomposition under increasing temperatures than the bacterial community. Our study highlights the roles of soil properties in the carbon pools of agricultural ecosystems. Future research should explore how these factors govern SOC decomposition, which is crucial for developing effective management strategies to address climate change.