Microbe-mineral competitive interactions control soil organic carbon turnover

Background/Question/Methods

The incorporation of explicit representation of biological complexity in soil carbon decomposition models may improve our ability to accurately predict terrestrial carbon-climate feedbacks. A new generation of microbe-explicit soil decomposition models (MEMs) are being developed that represent soil biological complexity, but only a few take into account detailed biotic and abiotic components and competitive interactions in the complex soil system. In view of this, we have developed a MEM with a detailed component network, in which competitive interactions and microbial metabolism are explicitly modeled. The model behavior has been tested and is qualitatively consistent with many empirical studies, but further model development and evaluation with experimental data is needed. In this study, we aim to investigate how competitive interactions between microbes and mineral surfaces influence soil organic carbon (SOC) turnover. To explicitly consider microbe-mineral interactions, we further develop the model by incorporating a mineral protection process and a dissolved organic carbon-dependent microbial physiological activity function. Two carbon isotope labeled addition experiments with a varying range of soil properties are used to test, parameterize, and evaluate the model behaviors. Model sensitivity to key parameters is analyzed, and the importance of microbe-mineral competitive interactions in controlling SOC turnover is discussed. 

Results/Conclusions

Preliminary results show that the developed MEM is able to well simulate the dynamics of each soil carbon component including the evolutions of carbon dioxide efflux and microbial biomass, and microbe-mineral competitive interactions play a key role in controlling SOC turnover.