** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** SOYBEANS ARE A LEADING COMPONENT OF GLOBAL SUSTAINABLE AGRICULTURE AND FOOD SECURITY BECAUSE OF THEIR HIGH PROTEIN CONTENT AND RELATIVELY LOW FERTILIZER DEMANDS, DUE TO THEIR NITROGEN-FIXING RHIZOBIAL MUTUALISTS. IN THE UNITED STATES, SOYBEANS ARE THE LARGEST CROP BY ACREAGE AND THE SECOND LARGEST CASH CROP AT $41 BILLION ANNUALLY. HOWEVER, SOYBEAN FARMING IS ENVIRONMENTALLY COSTLY DUE TO INTENSIVE PESTICIDE USE, AND ECONOMICALLY RISKY DUE TO NEARLY COMPLETE DEPENDENCE ON RAINFALL.SOYBEANS ASSOCIATE WITH A SPECIFIC GROUP OF BACTERIA CALLED RHIZOBIA IN A MUTUALLY BENEFICIAL RELATIONSHIP, WHERE THE RHIZOBIA PROVIDE NITROGEN TO THE PLANTS IN EXCHANGE FOR SUGARS DERIVED THROUGH PHOTOSYNTHESIS. SOYBEAN FARMERS CAN ENHANCE THEIR YIELD BY INOCULATING SOYBEAN FIELDS WITH RHIZOBIAL BACTERIA. ALTHOUGH SOYBEANS CAN SIMULTANEOUSLY ASSOCIATE WITH MULTIPLE RHIZOBIAL STRAINS, AND DIFFERENT STRAINS ARE DIFFERENTIALLY TOLERANT OF DROUGHT AND OTHER STRESSORS, NEARLY ALL RESEARCH AND AGRICULTURAL APPLICATIONS EMPHASIZE SINGLE-STRAIN INOCULATIONS.HERE, WE BORROW FROM ECOLOGICAL THEORY TO PREDICT THAT THE DIVERSITY OF RHIZOBIAL STRAINS MAY BUFFER SOYBEAN YIELD AGAINST COLLAPSES BY PROVIDING THE COMPLEMENTARY BENEFITS OF PROTECTING PLANTS FROM DROUGHT STRESS AND HERBIVORE DAMAGE. WE TEST THIS HYPOTHESIS WITH GREENHOUSE EXPERIMENTAL ASSAYS IN COMBINATION WITH OBSERVATIONAL AND EXPERIMENTAL DATA COLLECTION IN THE EXTENSIVE MARYLAND SOYBEAN VARIETAL TRIAL FARM NETWORK, WHICH WILL ALLOW OUR RESULTS TO BE APPLIED AT THE STATE-LEVEL AND TRANSLATED INTO RECOMMENDATIONS FOR THE COUNTRY. SPECIFICALLY, BY MANIPULATING SOYBEAN MICROBIAL (RHIZOBIA) COMMUNITIES WITHIN SOYBEAN FIELDS AT A BROAD SCALE, WE PREDICT BOTH IMPROVED CROP PERFORMANCE AND STABILITY THROUGH TIME, AS WELL AS LOWER COSTS FOR FARMERS THROUGH REDUCED RELIANCE ON PESTICIDES, IRRIGATION, AND FERTILIZER.THE END GOAL OF THIS RESEARCH IS TO INFORM THE DEVELOPMENT OF INNOVATIVE AND SUSTAINABLE SOLUTIONS TO ADDRESS THE THREAT POSED BY AN INCREASINGLY VARIABLE CLIMATE, WHICH IS PROJECTED TO LIMIT THE PRODUCTIVITY OF THE SOYBEAN PRODUCTION SYSTEM IN COMING DECADES.