Role of transport processes in formation of optimal microbial habitats and the root-microbe-soil carbon accrual continuum

土壤肥力对作物生产至关重要，取决于土壤有机碳(C)的有效性。一般来说，土壤C含量越高，土壤的生产力越高。农业用地的转换导致土壤C以二氧化碳的形式大量流失到大气中。提高土壤储存碳的能力不仅会增加国家的农业产量，还会降低大气中的二氧化碳水平。对土壤碳增强和储存机制的了解尚不完整。该项目旨在通过在微观尺度的物理、化学和生物学中使用新的概念方法和最先进的方法来填补目前关于土壤如何储存C的知识的重要空白。研究结果将导致农业和生态系统科学的进步，并将为开发新的农业和管理战略奠定基础，以增加土壤C收益和改善土壤肥力。该项目开发了一种新的概念范式，将微观尺度的物理、化学和生物学联系在一起，同时强调了目前被低估的C存储中最佳微生物栖息地的物理连通性的重要性。实验工作将为以下与碳相关的运输成分提供机制见解：(i)最佳微生物栖息地的性质和特性，即大多数新碳被微生物处理的物理空间；（ii）植物根系向最佳生境空间输送新碳的途径，微生物分解产物向潜在碳储存地点输送碳的途径；（iii）物理连接对细胞外酶运动的影响，以及它们拦截C产物或到达储存地点的能力。该项目将采用几种已建立的新型微尺度物理和生化分析工具，即用于表征土壤孔隙和根的x射线计算机微断层扫描，用于确定与根和土壤孔隙相关的新C的命运的13C标记和特定地点的微尺度13C采样，用于量化新C模式发展的土壤有机质的铯染色，以及用于细胞外酶活性微尺度制图的二维酶谱。本项目为博士后、研究生和本科生提供培训和研究机会。根据该项目的发现开发的材料将在密歇根州立大学推广服务组织的田间日和其他活动中报告给对提高农场土壤有机质水平感兴趣的农民。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Soil fertility is vital to crop production and is dependent on the availability of soil organic carbon (C). In general, the higher the level of soil C, the more productive the soil. Conversion of agricultural land has resulted in significant losses of soil C to the atmosphere as carbon dioxide (CO2). Enhancing the ability of soil to store C will not only increase national agricultural production, it will also decrease atmospheric CO2 levels. Understanding of the mechanisms of soil C enhancement and storage remains incomplete. This project aims to fill an important gap in current knowledge of how soils store C by using a new conceptual approach and state-of-the art methods in micro-scale physics, chemistry, and biology. The results will lead to progress in agricultural and ecosystem science, and will form the foundation for the development of new farming and management strategies for increasing soil C gains and improving soil fertility.This project develops a new conceptual paradigm that links together micro-scale physics, chemistry, and biology, while emphasizing the currently underestimated importance of physical connectivity of optimal microbial habitats in C storage. The experimental work will offer mechanistic insights into the following C-related transport components: (i) the nature and properties of optimal microbial habitats, i.e., the physical space where most of new C is microbially processed; (ii) the transport routes of new C from plant roots into the optimal habitat space, and of the products of microbial decomposition into potential C storage locations; and (iii) the effects of physical connections on movement of extracellular enzymes and their ability to intercept C products or reach them in storage locations. Several established and novel tools for micro-scale physical and biochemical analyses will be employed by the project, i.e, X-ray computed micro-tomography for characterization of soil pores and roots, 13C labeling and site-specific micro-scale 13C sampling for determining the fate of new C in relation to roots and soil pores, osmium staining of soil organic matter to quantify development of new C patterns, and 2D zymography for micro-scale mapping of extracellular enzyme activities. This project provides training and research opportunities for post-doctoral researchers, graduate, and undergraduate students. The materials developed based on the project's findings will be reported to the farmers interested in enhancing soil organic matter levels on their farms at Field days and other events organized by the Michigan State University Extension service.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.