The Role of Mineral Surface Chemistry in Determining the Composition and Mean Residence Time of the Stabilized Soil Organic Matter Pool.

Soil mineral assemblage influences the abundance and mean residence time of soil organic matter (SOM) both directly through sorption reactions and indirectly through influences on microbial communities. Though organo-mineral interactions are at the heart of soil organic matter cycling, current models mostly lack parameters describing specific mineral assemblages and phases and treat the mineral-bound pool as single homogenous entity with a uniform response to changes in climatic conditions. Observations of mineral-bound SOM fractions indicate that different  mineral assemblages tend to be associated with soil organics of specific molecular composition, and that these unique suites of organo-mineral  complexes differ in mean residence time. Evidence from laboratory incubations offers further confirmation of mineral surface chemistry exerting control over the molecular composition of the stabilized pool through illustration of abiotic partitioning of organics during decomposition.Taken together, both field and lab-based studies offer evidence that mineral surface chemistry plays a large role in determining the composition and mean residence time of the stable SOM pool. Taking these molecular-scale interactions into account will likely be necessary in gauging SOM response to climate change, suggesting a need for greater inclusion of mineral parameters in terrestrial C cycle models.