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

土壤有机质（SOM）是维系人类社会和地球生命的众多生态系统服务的关键纽带。它是微生物的主要食物来源，也是植物生长所需水分的主要储存库。SOM还为植物储存养分，吸收污染物，否则会污染食物和水的供应。土壤还通过储存碳来帮助调节气候，否则这些碳将被释放到大气中，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，以及反过来可能增加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。该项目涉及大量的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网络（NEON）已经收集的土壤样本，NEON是美国国家科学基金会在覆盖整个美国的环境监测方面的主要投资。这些样本将被保存下来，从这个项目中得到的数据将通过网络完全公开。一种新的模式的发展，在这种模式中，土壤有机质动力学的主要控制因素对分子结构的依赖程度低于其他土壤和生态系统特性，这在我们预测土壤有机质对环境变化的响应能力方面造成了知识空白。不同土壤有机质稳定机制的变化控制之间的关系，从在大空间尺度上操作的远端因素（如气候）到在更细空间尺度上操作的近端控制（如土壤理化性质），都没有明确的定义。研究人员将利用NEON建设期间收集的土壤样本，通过量化土壤类型和生态域的大陆尺度系统中SOM稳定的主要机制与生态系统控制规模（即，精细尺度，近尺度与宽尺度，远尺度）之间的关系来测试新兴范式。该项目将是第一个大陆尺度的SOM脆弱性评估，并将为控制土壤类型、土地利用类型和环境梯度的SOM稳定性提供新的预测性见解。研究结果将显著提高我们对土壤动力学的理解，这本身就是一项根本性的科学进步，同时也能更好地代表生态系统和碳-气候耦合模型中的土壤。该项目代表了开放的、面向社区的研究的新标准，支持来自大学、政府和非政府机构的研究人员的参与。它将通过主要的科学网络促进合作，这些网络越来越需要以解决社会面临的复杂问题所需的规模开展科学研究。通过参与这项研究，研究生和本科生将接受土壤科学最先进方法的培训，从中获得的见解将为决策者和资源管理人员有关碳封存和生态系统服务的决策提供信息。

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.