** 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 OBJECTIVES OF THIS PROJECT ARE TO: 1) CHARACTERIZE SOIL MICROBIOME COMMUNITY STRUCTURES, FOCUSING ON VIRUSES, BACTERIA, ARCHAEA, AND FUNGI; 2) INVESTIGATE THE TEMPORAL EFFECTS AND INTERACTION OF DIFFERENT AGRICULTURAL MANAGEMENT PRACTICES ON SOIL MICROBIOMES AND CROP PRODUCTION; 3) DETERMINE THE IMPACTS OF VIRAL PREDATION ON SOIL MICROBIOME STRUCTURE AND FUNCTION, INCLUDING CROP PRODUCTION; AND 4) DEVELOP A CONCEPTUAL MODEL FOR HOW VIRUSES IMPACT SOIL MICROBIOMES, RESPOND TO SOIL MANAGEMENT PRACTICES, AND ULTIMATELY IMPACT SYSTEM PRODUCTIVITY. THESE OBJECTIVES WILL BE MET THROUGH A COMBINATION OF FIELD STUDIES AND MANIPULATIVE EXPERIMENTS USING MICROCOSM (GREENHOUSE) APPROACHES. METAGENOMICS AND AMPLICON HIGH-THROUGHPUT SEQUENCING WILL BE APPLIED TO CHARACTERIZE SOIL MICROBIAL COMMUNITIES, QUANTIFY VIRAL IMPACTS, AND ULTIMATELY INTEGRATE VIRUSES AS PART OF AGRICULTURE SOIL MICROBIOMES. THE PROPOSED WORK WILL ADDRESS PROGRAM GOALS BY: 1) CHARACTERIZING MOLECULAR MECHANISMS INVOLVEDIN MICROBIOME ASSEMBLY AND INTERACTIONS IN VARIOUS ENVIRONMENTS AND GROWTH STAGES; AND 2) FUNCTIONALLY CHARACTERIZING MICROBIOMES, INCLUDING VIRUSES, AND THEIR ROLE IN OPTIMIZATION OF ENVIRONMENTAL PROCESSES (I.E., NITROGEN CYCLING, SOIL HEALTH, PLANT GROWTH AND PRODUCTIVITY). WE LACK MODELS THAT INCLUDE THE ROLE OF VIRUSES IN AGRICULTURAL PRODUCTION SYSTEMS, AND CHARACTERIZATION OF THE SOIL VIROME STANDS AS A MAJOR CHALLENGE OF THE 21ST CENTURY. THE PROPOSED STUDY WILL SUBSTANTIALLY IMPROVE OUR FUNDAMENTAL UNDERSTANDING OF HOW VIRUSES IMPACT MICROBIAL COMMUNITY DYNAMICS, SOIL HEALTH AND CROP PRODUCTIVITY UNDER DIFFERENT AGRICULTURAL PRACTICES. PROJECT OUTCOMES WILL HELP US BETTER DESIGN AND TARGET BEST MANAGEMENT PRACTICES THAT CAN INFORM BETTER DECISION MAKING AND SUSTAIN OUR NEXT GENERATION OF AGRICULTURE.