Determining how Organic Matter is Stabilized using a Unique Set of Soil Samples from across the U.S.

土壤有机质 (SOM) 是维持我们社会和地球生命的许多生态系统服务之间的关键联系。它是微生物的主要食物来源，也是植物生长所需的水的主要仓库。 SOM 还储存植物的养分并吸收污染物，否则可能会污染食物和水源。土壤还可以通过储存碳来帮助调节气候，否则碳会释放到大气中并导致气候变化。该项目研究了土壤中保护 SOM 不被微生物完全消耗的过程，以及相反地可以提高其对环境变化敏感性的过程。 研究人员还将研究气候变化和土地管理方式的变化如何影响土壤有机质的数量和稳定性。该项目涉及大量研究人员和实验室进行广泛的 SOM 分析。它利用了国家生态观测站网络 (NEON) 已经收集的土壤样本，NEON 是国家科学基金会在环境监测方面的一项重大投资，覆盖了整个美国。样本将被保存，该项目产生的数据将通过网络完全公开。新范式的演变，其中对SOM动态的主要控制较少依赖于分子结构，而不是其他土壤和生态系统特性，这在我们预测SOM对环境变化的响应的能力方面造成了知识差距。对不同 SOM 稳定机制的转移控制之间的关系，从在广泛空间尺度（例如气候）作用的远端因素到在更精细空间尺度（例如土壤理化性质）作用的近端控制，尚不清楚。研究人员将利用 NEON 建设过程中收集的土壤样本，通过量化 SOM 稳定的主要机制与跨大陆尺度土壤类型和生态域系统的生态系统控制规模（即精细尺度、近端与大尺度、远端）之间的关系来测试新兴范式。该项目将是第一个针对 SOM 脆弱性的大陆规模评估，并将对跨土壤类型、土地利用类型和环境梯度的 SOM 稳定性控制产生新的预测性见解。这些结果将显着提高我们对 SOM 动力学的理解，这本身就是一项根本性的科学进步，同时也能够更好地代表生态系统和耦合碳气候模型中的土壤。该项目代表了开放、面向社区的研究的新标准，支持大学、政府和非政府机构的研究人员参与。它将促进通过主要科学网络的合作，这些网络对于以解决社会面临的复杂问题所需的规模进行科学研究越来越必要。研究生和本科生将通过参与这项研究接受土壤科学最新方法的培训，从中获得的见解将为关注碳封存和生态系统服务的政策制定者和资源管理者的决策提供信息。

Soil organic matter (SOM) is a critical linkage among many ecosystem services that sustain our society and life on Earth. It is the primary food source for microbes and the principal storehouse of water necessary for plant growth. SOM also stores nutrients for plants and absorbs pollutants that otherwise could contaminate food and water supplies. Soils also help regulate climate by storing carbon that would otherwise be released to the atmosphere and contribute to climate change. This project investigates processes in the soil that protect SOM from being completely consumed by microbes and conversely, processes that could increase its sensitivity to environmental changes. The researchers will also study how climate change and changes in how land is managed affect the amount and stability of SOM. The project involves a large number of researchers and laboratories in conducting a wide range of SOM analyses. It takes advantage of soil samples already collected by the National Ecological Observatory Network (NEON), a major NSF investment in environmental monitoring that covers the entire United States. The samples will be preserved and the data that results from this project made fully public via the web.The evolution of a new paradigm, where the primary controls on SOM dynamics are less dependent on molecular structure than on other soil and ecosystem properties, has created a knowledge gap in our ability to predict the response of SOM to environmental change. The relationships among shifting controls over different SOM stabilization mechanisms, ranging from distal factors operating at broad spatial scales (e.g., climate) to proximal controls operating at finer spatial scales (e.g., soil physicochemical properties), are poorly defined. Investigators will test the emerging paradigm by quantifying relationships between the dominant mechanisms of SOM stabilization and the scale of the ecosystem controls (i.e., fine-scale, proximal vs. broad-scale, distal) across a continental-scale system of soil types and ecological domains, utilizing soil samples collected during the construction of NEON. This project will be the first continental-scale assessment of SOM vulnerability and will yield new, predictive insights into controls on SOM stability across soil types, land-use types and environmental gradients. The results will significantly improve our understanding of SOM dynamics, a fundamental scientific advancement in its own right, while also enabling better representation of soils in ecosystem and coupled carbon-climate models. The project represents a new standard in open, community-oriented research, supporting participation by researchers from universities, government and non-government agencies. It will facilitate collaboration through major scientific networks that are increasingly necessary to conduct science at the scale needed to address the complex issues facing society. Graduate and undergraduate students will receive training in state-of-the-science methods of soil science by participating in this research, and insights derived from it will inform decisions by policymakers and resource managers concerned with carbon sequestration and ecosystem services.