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

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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.