CAREER: Digging deeper to the roots of soil organic carbon formation, persistence, and function: An integrated research, education, and outreach program.

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Soil organic carbon (SOC) is critical for sustainable food production as it improves nutrient and water retention and enhances soil biological activity. SOC can also help mitigate climate change as it can act as a sink for atmospheric carbon dioxide. Soils in many ecosystems are depleted in SOC due to intensive management practices. Plants are a significant pathway through which atmospheric carbon can be channeled to SOC through the microbial decomposition of the shoot and root tissues. Thus, regenerative practices such as using diverse plant mixtures can potentially enhance SOC in managed ecosystems. However, obtaining a deeper understanding of how SOC is formed and, more importantly, where this newly formed carbon is sequestered, is critical to making informed decisions regarding plant species diversity for enhancing SOC. This research investigates how diverse plant mixtures with varying shoot and root chemistry interact with soil microbes and soil minerals to influence the formation, persistence, and function (e.g., nutrient availability) of SOC in ecosystems. The research is integrated with education and outreach activities while ensuring the participation of underrepresented groups in science. The educational activities include research training and experiential learning opportunities for K-12 and college students, and a new soils course for undergraduate and graduate students.SOC is highly heterogenous, with a multitude of biomolecules resulting from the decomposition of plant and microbial biomass that can be sequestered in different soil fractions. SOC stored in different physical fractions, such as particulate organic matter (POM; short-term sequestration) and mineral-associated organic matter (MAOM; long-term sequestration), will regulate the persistence of SOC under projected warming scenarios. The research evaluates how plant tissue type and plant functional type affect dissolved organic matter formation and chemical composition and, in turn, the interaction of these plant factors with microbial parameters and soil mineralogy to SOC formation, persistence, and function in POM and MAOM fractions. The research uses multifactor lab, greenhouse, multi-site field experiments, and advanced analytical techniques to obtain a molecular-level understanding of SOC dynamics in ecosystems. The research and outreach activities are integrated with cross-disciplinary training for K-12, undergraduate, and graduate students. The research provides a mechanistic understanding of SOC formation processes and informs knowledge-based management practices to enhance SOC sequestration, persistence, and function in ecosystems.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.