SOIL MICROBIOMES ARE WIDELY RECOGNIZED TO HAVE SIGNIFICANT POTENTIAL TO ENHANCE PLANT HEALTH AND PRODUCTIVITY IN CROPPING SYSTEMS. HOWEVER, WE UNDERSTAND LITTLE OF THE FACTORS THE MEDIATE THE COMPOSITION (WHO IS THERE) AND THE FUNCTIONAL CAPACITY (WHAT DO THEY DO) OF SOIL MICROBIAL COMMUNITIES. UNDERSTANDING THE FACTORS THAT MEDIATE COMPOSITION AND FUNCTION OF INDIGENOUS SOIL MICROBIOMES WILL PROVIDE A PLATFORM FOR THE DEVELOPMENT OF MANAGEMENT STRATEGIES TO OPTIMIZE MICROBIOMES TO SUPPORT HEALTHY CROPS AND STRONG CROP YIELDS. HERE WE WILL STUDY SOIL MICROBIOMES IN A UNIQUE, 58-YEAR LONG-TERM MONOCULTURE EXPERIMENT THAT INCORPORATES 5 CROP SPECIES WITH AND WITHOUT ANNUAL NITROGEN FERTILIZER APPLICATION AND WITH AND WITHOUT RESIDUE INCORPORATION. WE WILL USE A COMBINATION OF GENOMIC AND PHENOTYPIC ANALYSES OF SOIL BACTERIAL AND FUNGAL MICROBIOMES, IN CONJUNCTION WITH EXTENSIVE STUDY OF SOIL CARBON PROFILES UTILIZING PYROLYSIS GAS CHROMATOGRAPHIC MASS SPECTROLYSIS APPROACHES TO DETERMINE THE LINKAGES BETWEEN CROP MANAGEMENT, SOIL CARBON, AND SOIL MICROBIOME COMPOSITION AND FUNCTION. OUR PREVIOUS WORK SUGGESTS THAT SOIL CARBON CHARACTERISTICS ARE ONE KEY DRIVER OF SOIL MICROBIOMES. THE PROPOSED RESEARCH WILL DETERMINE THE POTENTIAL FOR CROP MANAGEMENT, ESPECIALLY NITROGEN FERTILIZER AND RESIDUE INCORPORATION TO OFFER A MEANS TO INFLUENCE SOIL CARBON AND SOIL MICROBIOMES TO ENHANCE CROP PRODUCTIVITY. WE HYPOTHESIZE THAT THIS RESEARCH WILL PROVIDE NOVEL INSIGHTS INTO DEVELOPING A NEW FIELD OF MICROBIAL NUTRITION' AS A PRACTICAL MEANS FOR ENHANCING CROPPING SYSTEM PRODUCTIVITY AND REDUCING RELIANCE ON PESTICIDES IN THE UNITED STATES.