**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** GLOBAL AGRICULTURE SECTORS ARE COMPETING FOR FINITE P RESERVES, AS IT IS AN ESSENTIAL NUTRIENT FOR PLANT GROWTH. BASED ON CURRENT METRICS, INEXPENSIVE ROCK PHOSPHATE IS EXPECTED TO BE DEPLETED WITHIN 50-100 YEARS. FOCUS ON P RESOURCE MANAGEMENT AND RECOVERY IS CRITICAL FOR ALL CROP PRODUCTION AREAS, INCLUDING SOIL-BASED, HYDROPONIC, AND AQUAPONIC SYSTEMS. IN THE SOILLESS AP SYSTEM, NITROGEN TRANSFORMATION AND UTILIZATION HAVE BEEN THE FOCUS OF NUTRIENT RESEARCH. THERE IS A STARK LACK OF INFORMATION ON OTHER ESSENTIAL NUTRIENTS IN AP, LIKE P, PARTICULARLY REGARDING PLANT-AVAILABLE FORMS. THIS KNOWLEDGE GAP LIMITS THE SUSTAINABILITY, PRODUCTIVITY, AND CAPACITY FOR CROP DIVERSIFICATION IN AP SYSTEMS. THE AIM OF THIS PROPOSAL IS TO UNDERSTAND HOW P RECOVERY/AVAILABILITY, MICROBIAL COMPOSITION OF THE PLANT RHIZOSPHERE, AND REGULATION OF MICROBIAL P-ENZYMES ARE AFFECTED BY ENVIRONMENTAL CONDITIONS. WE WILL CHARACTERIZE HOW THESE PARAMETERS CHANGE THROUGHOUT THE PLANT LIFECYCLE AND CAN BE OPTIMIZED TO IMPROVE PRODUCTIVITY AND PLANT QUALITY IN AP SYSTEMS. BY UNDERSTANDING THE INTERACTIONS AMONG THE HOST, ENVIRONMENT, AND THE MICROBIOME, AP PRACTITIONERS WILL HAVE A BETTER UNDERSTANDING OF NUTRIENT MANAGEMENT LEADING TO ENHANCED SYSTEM DESIGN, IMPROVED POTENTIAL FOR CROP DIVERSIFICATION, AND POSSIBLE INCREASED PROFITABILITY. RESULTS FROM THIS RESEARCH ARE APPLICABLE TO HOME PRACTITIONERS AND MULTIMILLION-DOLLAR AP FACILITIES ALIKE. MICROBIAL ASSOCIATIONS WITHIN THE PLANT RHIZOSPHERE REMAIN A BLACK BOX IN AP. GIVEN THEIR IRREPLACEABLE ROLE IN FUNCTION OF THE SYSTEM, IT IS SURPRISING THAT INVESTIGATION INTO THE SIGNIFICANT MICROBIAL COMMUNITIES THAT GOVERN AP SYSTEMS IS JUST BEGINNING. CURRENT RESEARCH ON THE TAXONOMIC PROFILE OF MICROORGANISMS IN AP HAS FOCUSED ON BIOFILTRATION AND SOLIDS FILTRATION COMPONENTS OF THE SYSTEM. THERE IS SOME, ALBEIT LIMITED, RESEARCH ON THE MICROBIAL COMPOSITION IN DIFFERENT COMPONENTS OF AP SYSTEMS. FEW STUDIES HAVE EXAMINED THE COMMUNITY COMPOSITION OF THE PLANT RHIZOSPHERE. THIS RESEARCH UTILIZED 16S RRNA SEQUENCING TO IDENTIFY THE QUANTITY AND PROPORTION OF TAXA; HOWEVER, THIS TECHNOLOGY IS LIMITED DUE TO THE LOW TAXONOMIC RESOLUTION AND BIAS FOR ASSIGNMENT OF SEQUENCES FOR THE VARIABLE REGION CHOSEN FOR THE ANALYSIS. IN ADDITION, 16S RRNA SEQUENCING ONLY DESCRIBES WHAT ORGANISMS ARE PRESENT AND DO NOT INFER FUNCTION OF THE COMMUNITY. WE PROPOSE TO USE A MULTI-PRONGED APPROACH TO CHARACTERIZE THE COMPOSITION AND FUNCTION OF THE PLANT RHIZOSPHERE MICROBIOME OF AP SYSTEMS THROUGH METAGENOMICS AND METATRANSCRIPTOMICS TECHNOLOGY, RESPECTIVELY. TO OUR KNOWLEDGE, THIS IS THE FIRST RESEARCH IN AP TO EMPLOY THIS APPROACH TO DETERMINE ENVIRONMENTAL DRIVERS THAT INFLUENCE PLANT RHIZOSPHERE MICROBIOTA COMPOSITION AND FUNCTION. THIS RESEARCH WILL LAY THE FOUNDATION FOR FUTURE MICROBIOME RESEARCH IN AP AND OPEN PATHWAYS FOR CONTINUED RESEARCH IN THE FIELD. FUNDING OF AP RESEARCH NOT ONLY PROVIDES ADVANCES IN SCIENTIFIC UNDERSTANDING OF THESE SYSTEMS BUT ALSO CAN POTENTIALLY PROVIDE KEY INSIGHTS INTO MICROBE-PLANT INTERACTION IN SOIL-BASED AGRICULTURE. A MAJOR FOCUS OF SOIL SYSTEMS IS HOW MICROBIOTA ARE RECRUITED TO THE RHIZOSPHERE BY THE PLANT. THESE MECHANISMS ARE MAINLY THEORETICAL BECAUSE RESULTS ARE DIFFICULT TO DISSECT DUE TO THE PHYSICAL AND CHEMICAL COMPLEXITY OF THE SOIL STRUCTURE. THIS COMPLEXITY CAN HINDER SEQUENCE-BASED APPROACHES TO MICROBIAL COMMUNITY FORMATION, GENETIC INFLUENCE ON NUTRIENT CYCLING , AND CAPACITY TO ENGINEER THE PLANT RHIZOSPHERE THROUGH PLANT-PROMOTING ORGANISMS. CONVERSELY, AP SYSTEMS ARE HIGHLY CONTROLLED AND HAVE LITTLE VARIATION IN PARAMETERS SUCH AS TEMPERATURE, PH, HYDRAULIC LOADING RATE, AND NUTRIENT APPLICATION. THE MATRIX SURROUNDING THE PLANT RHIZOSPHERE IS MARKEDLY LESS COMPLEX IN AP THAN IN SOIL. THESE SYSTEMS PROVIDE A MECHANISM TO CONDUCT CROSS-DISCIPLINARY RESEARCH ON THE PLANT RHIZOSPHERE THAT CAN BE APPLIED TO MULTIPLE AGRICULTURE PRODUCTION SYSTEMS. THE USE OF METAGENOMIC DATA TO GUIDE ISOLATION CAN PROVIDE FUTURE RESEARCH OPPORTUNITIES ON ENGINEERING THE PLANT RHIZOSPHERE.