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).

尽管土壤有机质的主要来源为植物残体输入，但在生物贡献于长效土壤有机质的研究背景下，微生物作为土壤有机碳固存介导者的作用日益受到认可。然而，当前对地下土壤过程的认知尚不足以构建微生物源碳流的模拟模型，尤其是在深层土壤中。本研究利用此前已被研究过的、位于加利福尼亚州圣克鲁斯以北的古海阶地（90 ka），针对土壤剖面三个深度（-25、-75和-125 cm），表征了土壤有机质库中部分最具动态性的组分——低分子量有机化合物（low molecular weight organic compounds, LMWOC）的短期（数天至数周）与中期（数月至数年）归趋。这类化合物是常见土壤有机质组分的单体，例如碳水化合物、蛋白质与有机酸。本研究结合实验室与野外培养技术，追踪了这些碳化合物在溶解态、可交换态、微生物结合态以及金属结合态土壤有机碳库中的归趋。本数据集包含土壤理化性质（pH值、土壤含水量、比表面积）、低分子量有机化合物周转动力学参数、可提取态（中性盐提取与连续提取）及总土壤有机碳库，其中涵盖微生物结合态与经连续提取获得的金属结合态土壤有机碳。