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

土壤有机质(SOM)是维持我们地球上的社会和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，也是植物生长所必需的主要水分储藏室。SOM还为植物储存养分，并吸收其他可能污染食物和水供应的污染物。土壤还通过储存碳来帮助调节气候，否则碳就会释放到大气中，并导致气候变化。该项目调查土壤中保护有机质不被微生物完全消耗的过程，反之，可以增加其对环境变化的敏感度的过程。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土壤有机质分析。它利用了国家生态观测网络(NEON)已经收集的土壤样本，该网络是NSF在环境监测方面的一项重大投资，覆盖整个美国。样本将被保存，该项目产生的数据将通过网络完全公开。一种新范式的演变，即对土壤有机质动态的主要控制比对其他土壤和生态系统属性的依赖更少地依赖于分子结构，这在我们预测土壤有机质对环境变化的反应的能力方面创造了一个知识缺口。对不同土壤有机质稳定机制的控制转移之间的关系，从在广泛空间尺度上操作的远端因素(例如气候)到在更精细空间尺度上操作的近端控制因素(例如土壤物理化学性质)，都没有得到很好的界定。研究人员将利用在霓虹灯建造过程中收集的土壤样本，通过量化土壤有机质稳定的主要机制与整个大陆尺度土壤类型和生态域系统的生态系统控制规模(即细尺度、近尺度与大尺度、远尺度)之间的关系，来测试新出现的范式。该项目将是第一个大陆范围的土壤有机质脆弱性评估，并将对土壤类型、土地利用类型和环境梯度的土壤有机质稳定性控制产生新的预测性见解。这些结果将显著提高我们对土壤有机质动力学的理解，这本身就是一项根本性的科学进步，同时也使土壤在生态系统和碳-气候耦合模型中能够更好地代表土壤。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参与。它将通过重大科学网络促进合作，这些网络对于在解决社会面临的复杂问题所需的规模开展科学工作日益必要。研究生和本科生将通过参与这项研究接受关于土壤科学最新方法的培训，由此得出的见解将为关注碳固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参考。

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.