Short vs intermediate-term fate of glucose and oxalic acid in surface and subsurface soils of a coastal grassland near Santa Cruz California

Though the primary sources of organic matter to soil are plant inputs, the role of microorganisms as mediators of soil organic carbon preservation is increasingly recognized in the context of biological contributions to long-lived soil organic matter. However, current knowledge of sub-soil processes is insufficient to model microbial-derived carbon flow particularly at depth. Using a previously studied paleo-marine terrace (90 ka) located just north of Santa Cruz, CA, we characterized for three depths in the soil profile (-25, -75, and -125 cm) the short-term (days to weeks) and intermediate-term (months to years) fate of some of the most dynamic components of soil organic matter pools, low molecular weight organic compounds (LMWOC). These are the monomers of common soil organic manner constituents, e.g carbohydrates, proteins and organic acids. Using a combination of laboratory and field incubation techniques we traced the fate of these carbon compounds through dissolved, exchangeable, microbial, and metal-associated soil organic carbon pools. Included in this dataset are soil physicochemical characteristics (pH, soil moisture, surface area), LMWOC turnover kinetics, extractable (neutral-salt and sequentially extracted) and total soil organic C pools including microbial-associated, and metal-associated soil organic carbon (sequentially extracted).