Conceptual frameworks of the processes that control carbon (C) stabilization in soil organic matter (SOM) are currently undergoing a major revision. Older theoretical models hold that SOM is comprised of recalcitrant plant-derived compounds, which are stabile in soils due to their inherent chemical complexity. In contrast to these long-held paradigms, new analytical techniques are revealing that most old soil C is comprised of simple, microbially-derived organic molecules which are stabilized on mineral surfaces. Despite this exciting new evidence, the mineralogical and microbial processes that govern the transformation of plant C inputs into stable SOM are still poorly understood.

In this inspire session, we will highlight new evidence for interacting microbial and mineralogical controls over SOM formation and turnover. Speakers will explore the relationships among microbial physiology, soil mineralogy, and SOM with multiple complimentary techniques, including soil metagenomics, X-ray computed microtomography, high resolution mass spectrometry, isotope labeling, and model simulations. The session will synthesize both empirical and theoretical advances, taking a multi-disciplinary and multi-scale approach that integrates processes occurring within individual soil aggregates with ecosystem-scale and global C fluxes.