** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** LEVERAGING THE ECOSYSTEM SERVICES PROVIDED BY SOIL MICROBIAL COMMUNITIES HAS THE POTENTIAL TO SUPPORT SUSTAINABLE AGRICULTURE. TO IMPROVE SUSTAINABILITY, FARMERS ARE INCREASINGLY GROWING COVER CROP MIXTURES THAT PROVIDE SPECIFIC ECOSYSTEM SERVICES, LIKE NITROGEN FIXATION, CARBON STABILIZATION, AND WEED SUPPRESSION. SOME OF THESE SERVICES, LIKE NITROGEN FIXATION, ARE PROVIDED BY KNOWN LEGUME-ASSOCIATED MICROBES. STILL, MANY OTHER ECOSYSTEM BENEFITS AND FUNCTIONS OF THE SOIL MICROBIAL COMMUNITY ARE POORLY UNDERSTOOD. THIS FOUNDATIONAL UNDERSTANDING IS ESSENTIAL TO PREDICT THE ADDITIVE MICROBIAL BENEFITS OF GROWING MIXTURES OF COVER CROPS. THIS RESEARCH PROJECT WILL ADDRESS THESE GAPS BY DETERMINING THE MICROBES AND MICROBIAL FUNCTIONS EACH COVER CROP SPECIES PROMOTES AND HOW MICROBIAL FUNCTIONS EMERGE IN MIXTURES. THIS PROJECT WILL UTILIZE 1) CONTROLLED GREENHOUSE EXPERIMENTS TO ASSESS METABOLICALLY AND TRANSCRIPTIONALLY ACTIVE MICROBES AND 2) FIELD EXPERIMENTS TO DETERMINE PATTERNS OF MICROBIAL EVOLUTION IN A LONG-TERM FIELD EXPERIMENT IN PENNSYLVANIA. THIS RESEARCH WILL FACILITATE THE MANAGEMENT AND PREDICTION OF MICROBIAL FUNCTIONS IN COVER CROP MIXTURES ALLOWING FARMERS TO BETTER HARNESS THE BELOW-GROUND BENEFITS OF MICROBES. THIS PREDOCTORAL FELLOWSHIP ADDRESSES THE FARM BILL PRIORITY OF PLANT HEALTH, PLANT PRODUCTION, AND PLANT PRODUCTS BY OPENING THE DOOR TO EFFECTIVELY MANAGING ECOSYSTEM SERVICES VIA COVER CROP MIXTURES. FURTHERMORE, THIS PROJECT WILL SUPPORT PD HARRIS'S DEVELOPMENT INTO A FUTURE LEADER IN AGRICULTURE THROUGH GAINING SKILLS IN BIOINFORMATICS, LEADERSHIP, MENTORSHIP, COLLABORATION, AND COMMUNICATION WITH SCIENTIFIC AND LAY AUDIENCES.