Chemical characterization and function of soil organic nitrogen in prairie agroecosystems

草原农业生态系统土壤有机氮的化学特征及功能

• 批准号: 203182-2011
• 负责人: Walley, Frances
• 金额: $ 2.4万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=546278
• 关键词: Chemical; characterization; function; soil; organic

My program focuses on soil N and N-cycling. Of particular interest has been the examination of soil organic N (SON) fractions with the goal of understanding how various organic N pools contribute to bioavailable N, both from an agricultural sustainability perspective (i.e., soil quality and soil fertility) and from an environmental perspective (i.e., environmental losses). The proposed research builds on existing work in which we use synchrotron-based N and C K-edge X-ray absorption near-edge structure (N- and C-XANES) to examine SON in bulk soil, and soil chemical and physical fractions. The long-term objective is to characterize the molecular composition of key chemical and physical SON pools, with the goal of identifying measureable bioavailable SON pools and examining their implications for ecological functions within agricultural ecosystems. The short-term objectives of the proposed research are: 1) to examine and characterize the occurrence and nature of unique SON compounds as affected by agricultural management practices and define relationships between the structure of these compounds and N bioavailability; and 2) to examine the speciation of SON in stable soil micro- and macro-aggregates, with the goal of elucidating potential mechanisms by which N (and C) is stabilized and protected in these physical fractions. Although others have used synchrotron radiation to examine soil and environmental samples, limited attention has been paid to SON largely due to the low levels of N typically present in soils, together with relatively low detection limits. Ongoing improvements to detections limits have opened new avenues for exploration of SON. Our work represents some of the earliest applications of N-XANES to soil and environmental samples, and we are well positioned to further advance this highly novel analytical technique as a defendable approach to examining SON at the molecular level, to resolve some of the controversy existing in the literature regarding the nature of SON, and to ascertain mechanisms by which SON is stabilized in soil chemical and physical (i.e., soil aggregates) fractions.

我的项目重点是土壤氮和氮循环。特别令人感兴趣的是对土壤有机氮（SON）部分的检查，目的是从农业可持续性角度（即土壤质量和土壤肥力）和环境角度了解各种有机氮库如何促进生物可利用氮（即环境损失）。拟议的研究建立在现有工作的基础上，其中我们使用基于同步加速器的 N 和 C K 边缘 X 射线吸收近边缘结构（N-和 C-XANES）来检查大块土壤中的 SON 以及土壤化学和物理成分。 长期目标是表征关键化学和物理 SON 库的分子组成，目标是确定可测量的生物可利用 SON 库并检查其对农业生态系统内生态功能的影响。拟议研究的短期目标是：1）检查和表征受农业管理实践影响的独特 SON 化合物的出现和性质，并确定这些化合物的结构与氮生物利用度之间的关系； 2) 检查稳定土壤微观和宏观团聚体中 SON 的形态，目的是阐明氮（和碳）在这些物理组分中稳定和受到保护的潜在机制。尽管其他人已经使用同步加速器辐射来检查土壤和环境样本，但对 SON 的关注有限，主要是由于土壤中通常存在的氮含量较低，且检测限相对较低。检测极限的不断改进为 SON 的探索开辟了新的途径。我们的工作代表了 N-XANES 在土壤和环境样品中的一些最早应用，我们有能力进一步推进这种高度新颖的分析技术，作为在分子水平上检查 SON 的可靠方法，以解决现有的一些争议在有关 SON 性质的文献中，并确定 SON 在土壤化学和物理（即土壤团聚体）部分中稳定的机制。