AGRICULTURAL SUSTAINABILITY CAN BE ACHIEVED THROUGH GREATER RELIANCE ON BIODIVERSITY AND ECOSYSTEM SERVICES, INCLUDING FROM SOILS AND THEIR BIOTA. SOIL ARTHROPODS ARE A KEY COMPONENT OF SOIL BIODIVERSITY AND AFFECT SOIL HEALTH AND PLANT PERFORMANCE THROUGH THEIR INTERACTIONS WITH PLANTS AND SOIL MICROBES. HOWEVER, THESE EFFECTS HAVE LARGELY BEEN STUDIED IN UNMANAGED SYSTEMS AND OUR UNDERSTANDING OF THESE INTERACTIONS IS LIMITED IN AGROECOSYSTEMS. GIVEN THE POTENTIAL FOR SOIL ARTHROPODS TO INFLUENCE CROP PERFORMANCE AND ENHANCE AGRICULTURAL SUSTAINABILITY, IT IS VITAL TO RIGOROUSLY INVESTIGATE THE INFLUENCE OF SOIL ARTHROPOD COMMUNITIES ON CROP PERFORMANCE AND RESISTANCE TO ABOVEGROUND PEST HERBIVORES IN AGROECOSYSTEMS. TO ADDRESS THESE KNOWLEDGE GAPS, THIS PROPOSAL WILL (1) DETERMINE HOW SOIL ARTHROPOD COMMUNITIES DERIVED DIRECTLY FROM AGROECOSYSTEM SOILS INFLUENCE THE GROWTH AND PERFORMANCE OF WINTER WHEAT AND WINTER PEA, AND (2) EXAMINE HOW MANIPULATING SOIL ARTHROPOD COMMUNITY STRUCTURE INFLUENCES CROP GROWTH AND RESISTANCE TO ABOVEGROUND HERBIVORES FROM DIFFERENT FEEDING GUILDS. SPECIFICALLY, THIS RESEARCH WILL MEASURE THE EFFECTS OF SOIL ARTHROPODS ON CROP ROOT AND SHOOT BIOMASS, ROOT ARCHITECTURE, PHYTOHORMONES, NUTRIENT CYCLING AND ACQUISITION, AND THE BIOMASS AND COMPOSITION OF THE SOIL MICROBIAL COMMUNITY. ACCORDINGLY, THIS PROPOSAL ADDRESSES THE TWO AFRI PROGRAM AREA PRIORITIES OF PLANT HEALTH AND PRODUCTION AND PLANT PRODUCTS AND AGRICULTURE SYSTEMS AND TECHNOLOGY. THIS PROPOSAL ALSO ADDRESSES THE GOALS OF THE AFRI EWD PROGRAM BY PROVIDING INTERDISCIPLINARY CAREER DEVELOPMENT OPPORTUNITIES FOR PD ELMQUIST. THIS RESEARCH WILL HELP TO EVALUATE THE IMPORTANCE OF SOIL ARTHROPOD COMMUNITIES FOR IMPROVING CROP PERFORMANCE AND HERBIVORE RESISTANCE IN SUSTAINABLE AGRICULTURAL SYSTEMS.