CAREER: Dynamics and Vulnerability of Mineral-Organic Associations in the Rhizosphere

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Soils are the largest and most dynamic terrestrial carbon reservoir - storing more than twice as much carbon as atmosphere and biosphere combined - and, thus, directly respond to and drive global climate. Up to 90% of soil carbon is stored in organic compounds intimately associated with reactive minerals. Such mineral-organic associations (MOAs) can protect carbon compounds against microbial or enzymatic attack for centuries to millennia. Consequently, current carbon cycling models assume that, once formed, MOAs and carbon protected therein are relatively inert to environmental disturbance. However, plant roots and associated microbes in the rhizosphere have a well-known ability to transform minerals through dissolution and exchange reactions. Yet, the impact of such root- and microbially-mediated reactions on MOAs and carbon protected therein remain elusive. A better understanding the response of otherwise stable MOAs to rhizosphere processes is critical to improving predictions of the vulnerability of this vast soil carbon reservoir to environmental change. Without a robust representations of root-driven MOA destabilization, models will insufficiently project soil carbon-climate feedbacks.The overall objectives of this NSF CAREER project are to develop mechanistic understanding of the dynamics and vulnerability of MOAs in the rhizosphere and to train diverse, creative, and technically skilled environmental scientists to meet the most pressing environmental challenges of the 21st century. The project aims to (i) identify the molecular mechanisms, (ii) define biogeochemical drivers, and (iii) assess environmental controls of root-driven MOA destabilization within rhizosphere soil. To experimentally resolve root-microbe-mineral interactions in dynamic rhizosphere microenvironments, this study will develop novel in-situ profiling approaches. These research objectives are closely aligned with outreach and education activities at multiple levels, structured around the study of important plant-microbe-soil interactions. Built on strong engagement with local partners and commitment to interdisciplinary education, this project will launch a collaboration with Holyoke Community College to increase representation of low-income and minority students in UMass's environmental science degree program and create a new course incorporating Design Thinking approaches, providing graduate students and postdocs with the creative problem-solving and collaborative skills urgently needed to solve the complex environmental challenges facing society today.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.