**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** USING COVER CROP (CC) MIXTURES ENABLES A WIDER ARRAY OF ECOSYSTEM BENEFITS TO BE ACHIEVED. WITHIN MIXTURES, ECOSYSTEM FUNCTIONS PROVIDED BY INDIVIDUAL CC SPECIES ARE PROPORTIONAL TO THEIR ABUNDANCE. HOWEVER, RESEARCH ON COVER CROP MIXTURES IS HINDERED BECAUSE WE ONLY CHARACTERIZE THE COMPOSITION OF CC SPECIES ABOVEGROUND DUE TO THE DIFFICULTY OF IDENTIFYING ROOTS TO SPECIES. BECAUSE MANY ECOSYSTEM SERVICES ARE PROVIDED BY ROOTS, CHARACTERIZING CC BELOWGROUND COMPOSITION WILL ENABLE US TO DESIGN MIXTURES THAT ARE MORE EFFECTIVE AT ECOSYSTEM SERVICE PROVISIONING. I HAVE DEVELOPED A MOLECULAR APPROACH TO QUANTIFY THE COMPOSITION OF FUNCTIONALLY DIVERSE CC SPECIES WITHIN MIXTURES. WITH THIS METHOD, I WILL: OBJ. 1) REFINE THE METHOD TO BE READILY TRANSFERABLE TO OTHER SPECIES COMBINATIONS BY ACCOUNTING FOR COMMON BIASES WHICH COULD LEAD TO INACCURATE ABUNDANCE ESTIMATES; OBJ, 2) DETERMINE TO WHAT EXTENT CC ABOVEGROUND COMPOSITION IN SPECIES MIXTURES REFLECTS BELOWGROUND ROOT COMPOSITION; AND OBJ. 3) DETERMINE IF CC ROOT COMPOSITION IN MIXTURES PREDICTS THE PROVISIONING OF ECOSYSTEM SERVICE MULTIFUNCTIONALITY. OUTCOMES INCLUDE 1) THE APPLICATION OF THE ROOT ABUNDANCE METHOD BEYOND OUR STUDY SYSTEM, 2) A DEEPER UNDERSTANDING OF CC ALLOCATION IN MIXTURES AND WHETHER ROOT BIOMASS CAN BE ESTIMATED FROM SHOOT BIOMASS, 3) THE MECHANISMS GOVERNING CC MIXTURE PROVISIONING OF ECOSYSTEM SERVICE MULTIFUNCTIONALITY, AND ULTIMATELY 4) IMPROVED DESIGN AND GREATER ADOPTION OF CC MIXTURES. THIS PROJECT CONTAINS TRAINING ACTIVITIES SUCH AS ATTENDING AN INTENSIVE BIOINFORMATICS WORKSHOP, MENTORING AN UNDERGRADUATE STUDENT, AND SCIENTIFIC PRESENTATIONS.