**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** HIGH-INTENSITY SPECIALTY FRUIT AND VEGETABLE CROP PRODUCTION DEPEND ON FUMIGATION TO REDUCE DISEASE, NEMATODE, AND WEED PRESSURE PRIOR TO PLANTING. WHILE THE IMPACTS OF FUMIGANTS ON TARGETED SOILBORNE PATHOGENS ARE WELL DOCUMENTED, THEY CAN ALSO IMPACT THE ABUNDANCE AND DIVERSITY OF NON-TARGET SOIL MICROORGANISMS. AS THE SOIL MICROBIOME IS A CRITICAL COMPONENT OF AGRICULTURAL PRODUCTION, THE BROAD MODES OF ACTION OF FUMIGATION COULD INFLUENCE CROP PRODUCTION BY REDUCING ABUNDANCES OF CRITICAL PLANT-GROWTH-PROMOTING ORGANISMS PROVIDING NUTRIENT AVAILABILITY AND NATURAL BIOCONTROL. HOWEVER, WHILE GENERAL RESPONSES OF SOIL MICROBIAL DIVERSITY TO FUMIGATION HAVE BEEN EXAMINED, THERE IS LIMITED INFORMATION REGARDING THE IMPACTS TO SOIL MICROBIOME FUNCTIONS, PARTICULARLY AS THEY RELATE TO CROP PRODUCTION, OVER MULTIPLE GROWING SEASONS, AND IN DIFFERENT SOIL ENVIRONMENTS.THIS PROJECT WILL ASSESS THE INTERACTIONS BETWEEN FUMIGANTS, THE SOIL MICROBIOME, WITH A FOCUS ON PLANT-GROWTH-PROMOTING BACTERIA INVOLVED IN NITROGEN CYCLING AND BIOCONTROL, AND THE IMPACTS ON CROP PRODUCTION. FIELD TRIALS WILL BE ESTABLISHED IN UNIVERSITY AND COMMERCIAL FARMS. TRIALS AT THE UNIVERSITY FARM WILL FOCUS ON DETERMINING SHORT- AND LONG-TERM IMPACTS ON THE SOIL MICROBIOME COMPOSITION AND FUNCTION DUE TO DIFFERENT FUMIGANT MIXTURES. TRIALS AT COMMERCIAL FARMS WILL EXAMINE THE INFLUENCE OF SOIL ENVIRONMENT AND MANAGEMENT PRACTICES ON FUMIGANT IMPACTS TO SOIL MICROBIOME FUNCTIONS.OUR PROJECT WILL HELP FILL MAJOR KNOWLEDGE GAPS IN CHARACTERIZING AGRICULTURAL MICROBIOMES AND MICROBIOME FUNCTIONS ACROSS AGRICULTURAL PRODUCTION SYSTEMS BY FUNCTIONALLY CHARACTERIZING MICROBIOMES THAT MAY BE IMPACTED BY FUMIGATION AND INFLUENCE PROCESSES THAT ARE CRITICAL FOR CROP PRODUCTION, INCLUDING NUTRIENT CYCLING AND PEST AND DISEASE CONTROL.