** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE GOAL OF OUR PROPOSED RESEARCH IS TO DESIGN COVER CROP MIXTURES THAT ARE MORE EFFECTIVE AT PROVIDING AN ARRAY OF ECOSYSTEM SERVICES. CURRENTLY, OUR ABILITY TO DESIGN BETTER PERFORMING COVER CROP MIXTURES IS LIMITED BY A LACK OF UNDERSTANDING OF THE RELATIONSHIP BETWEEN RELATIVE ABUNDANCE OF FUNCTIONALLY DIVERSE SPECIES IN MIXTURES AND THEIR PROVISIONING OF ECOSYSTEM SERVICES, AS WELL AS HOW THIS IS AFFECTED BY ENVIRONMENTAL CONDITIONS AND MANAGEMENT. TO ADDRESS THESE KNOWLEDGE GAPS, WE WILL: OBJ. 1) EVALUATE HOW INITIAL SEEDING RATE OF THREE COVER CROP SPECIES INTERACTS WITH ENVIRONMENTAL CONDITIONS TO DETERMINE THE FINAL MIXTURE COMPOSITION; OBJ. 2) DETERMINE THE COVER CROP MIXTURE SEEDING RATE THAT OPTIMIZES INDIVIDUAL ECOSYSTEM SERVICE FUNCTIONS, AS WELL AS OVERALL MULTIFUNCTIONALITY; OBJ. 3) EVALUATE HOW VARIATION IN BOTH WEATHER AND MANAGEMENT AFFECT COVER CROP MIXTURE COMPOSITION AND THE ASSOCIATED ECOSYSTEM SERVICES PROVIDED BY COVER CROP MONOCULTURES AND MIXTURES ACROSS 16 YEARS OF PSU'S COVER CROP COCKTAILS EXPERIMENT. WE WILL ADDRESS OBJ. 1 AND 2 THROUGH A NOVEL PROPORTIONAL REPLACEMENT SERIES DESIGN FIELD EXPERIMENT (CONSISTING OF MIXTURES VARYING IN PROPORTIONS OF THREE FUNCTIONALLY DISTINCT COVER CROPS) REPLICATED ACROSS TWO SITES OVER THREE YEARS COMBINED WITH DIVERSITY INTERACTION MODELS. ADDITIONALLY, WE WILL UTILIZE 16 YEARS OF DATA COMPILED FROM PSU'S COVER CROP COCKTAILS EXPERIMENT TO EVALUATE HOW ENVIRONMENTAL VARIATION INFLUENCES MIXTURE COMPOSITION AND THE RESULTING ECOSYSTEM SERVICES. RESULTS FROM THE PROPOSED RESEARCH WILL AID FARMERS IN DESIGNING COVER CROP MIXTURES THAT ARE FARM-TUNED TO THEIR DESIRED ECOSYSTEM FUNCTIONS, FARMING OPERATIONS, AND CLIMATE.