SGER: Preferential and Stable Sorption of N- vs. C-rich Soil Organic Matter on Mineral Surfaces

尽管公认的重要性，土壤有机质（SOM）的土壤化学，土壤水文学和土壤结构，一个详细的机械理解的因素，影响SOM的形成和稳定性尚未出现。 这一探索性研究工作的智力价值在于在土壤微团聚体的尺度上检查和探索SOM的形成和稳定性。 具体而言，使用尺寸密度分级，放射性碳测年的SOM，和氮含量测定，研究将测试一个新的假设，土壤有机化合物最接近矿物表面是最稳定的，与稳定性降低的有机物从矿物表面的距离增加。 第二种假设假定矿物表面附近的土壤有机化合物特别富含氮，并且它们的含氮组分（胺基）负责它们与矿物表面特别稳定的结合。 这项研究的广泛影响有许多方面。 土壤有机质对全球福祉和安全至关重要，因为SOM提供了维持农业和森林生产力所需的大部分氮，其他养分和土壤结构。 全球范围内SOM形成和/或稳定性的变化可能会对大气二氧化碳浓度产生影响，从而影响全球气候。更好地了解控制有机质形成和损失的机制，将大大提高我们的能力，有效地管理有机质的商品生产和侵蚀控制，并减轻土壤二氧化碳通量到大气中。

Despite the generally acknowledged importance of soil organic matter (SOM) to soil chemistry, soil hydrology, and soil structure, a detailed mechanistic understanding of the factors that influence SOM formation and stability has yet to emerge. The intellectual merit of this exploratory research effort lies in the examination and exploration of SOM formation and stability at the scale of the soil microaggregate. Specifically, using size-density-fractionation, radiocarbon dating of SOM, and nitrogen content determinations, the research will test a novel hypothesis that soil organic compounds nearest to mineral surfaces are the most stabilized, with stability decreasing with increasing distance of the organics from the mineral surfaces. A second hypothesis posits that soil organic compounds near mineral surfaces are especially nitrogen-rich, and that their nitrogen-containing components (amine groups) are responsible for their especially stable binding to mineral surfaces. There are many facets to the broader impacts of this research. Soil organic matter is critical to global well-being and security in that SOM supplies in large part the nitrogen, other nutrients, and soil structure needed to sustain agricultural and forest productivity. Changes in SOM formation and/or stability on a global scale may have consequences for atmospheric carbon dioxide concentrations and thus global climate. A better understanding of the mechanisms controlling SOM formation and loss will greatly improve our ability to efficiently manage SOM for commodity production and erosion control, and to mitigate soil carbon dioxide flux to the atmosphere.