** 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 BIOLOGICAL, CHEMICAL AND PHYSICAL PROPERTIES OF SOIL IMMEDIATELY SURROUNDING ROOTS DIFFER SUBSTANTIALLY FROM BULK SOIL AND PLAY A CRITICAL ROLE IN GLOBALLY SIGNIFICANT ECOLOGICAL PROCESSES INCLUDING SOIL FORMATION, NITROGEN CYCLING AND CARBON CYCLING. DESPITE ITS SMALL SPATIAL EXTENT, THIS ROOT ZONE (THE RHIZOSPHERE) IS RESPONSIBLE FOR A DISPROPORTIONATELY LARGE PERCENTAGE OF TRANSFORMATIONS OF CHEMICAL SPECIES THAT CONTROL SOIL ORGANIC CARBON ACCRUAL AND LOSS. A BETTER UNDERSTANDING OF NUTRIENT TRANSFORMATIONS WITHIN THE RHIZOSPHERE WOULD INFORM AGRICULTURAL AND ECOLOGICAL DECISION-MAKING TO IMPROVE PLANT PRODUCTIVITY, ECOLOGICAL RESILIENCE,AND AGRICULTURAL SUSTAINABILITY.THE OVERALL OBJECTIVE OF THIS PROJECT IS TO EXPLORE THE COMPLEX INTERACTIONS BETWEEN ROOTS, MICROBIAL COMMUNITIES, AND ORGANIC MATTER IN THE RHIZOSPHERE UNDER NATURAL CONDITIONS USING A NOVEL INTEGRATED MEASUREMENT SYSTEM THAT QUANTIFIES DISSOLVED SPECIES, SOIL GASES, AND THEIR TRANSFORMATIONS WITH HIGH SPATIAL AND TEMPORAL RESOLUTION. AN AUTOMATED, NON-DESTRUCTIVE, IN-SITU, SOIL LIQUID SAMPLING SYSTEM WITH HIGH SPATIAL (MILLIMETER), TEMPORAL (MINUTE) AND MOLECULAR RESOLUTION WILL BE DEVELOPED TO OBSERVE LOW MOLECULAR WEIGHT DISSOLVED ORGANIC MATTER TRANSFORMATIONS AT PREVIOUSLY INACCESSIBLE SPATIOTEMPORAL SCALES. ARRAYS OF THESE MICRODIALYSIS-BASED PROBES WILL BE COMBINED WITH EXISTING GAS PROBES AND WITH METAGENOMIC/METATRANSCRIPTOMIC MICROBIAL CHARACTERIZATION TO INFORM AND CHALLENGE RHIZOSPHERE REACTIVE TRANSPORT MODELS.A COMPREHENSIVE UNDERSTANDING OF THE DYNAMIC PROCESSES OCCURRING IN THE RHIZOSPHERE RESULTING FROM ROOT GROWTH, EXUDATION, RESPIRATION, WATER/NUTRIENT UPTAKE AND MICROBIAL ACTIVITY REQUIRES AN INTERDISCIPLINARY APPROACH THAT COMBINES HIGH-FIDELITY MEASUREMENTS OF RHIZOSPHERE CHEMICAL TRANSFORMATIONS, MICROBIAL CHARACTERIZATION, AND REACTIVE TRANSPORT MODELLING. THIS PROJECT WILL ADDRESS A SET OF RESEARCH QUESTIONS AIMED AT EXPLORING RESOURCE UTILIZATION IN THE RHIZOSPHERE AT SPATIAL AND TEMPORAL SCALES THAT HAVE BEEN PREVIOUSLY INACCESSIBLE. THE RESULTING DATA WILL INFORM AND CHALLENGE SOPHISTICATED REACTIVE TRANSPORT MODELS TO DEVELOP PREDICTIVE CAPACITY ADDRESSING FACTORS DRIVING SOIL ORGANIC MATTER DECOMPOSITION IN THE RHIZOSPHERE, THE FATE OF DECOMPOSITION PRODUCTS AND THE IMPACT OF ENVIRONMENTAL FACTORS AND SYMBIOTIC RELATIONSHIPS. THIS RESEARCH WILL PRODUCE NEW DATASETS THAT HELP ECOLOGYAND AGRONOMYRESEARCHERS BETTER UNDERSTAND THE RELATIONSHIP BETWEEN SOIL NUTRIENTS AND ROOT UPTAKE, AND HOW THE ROOT-SOIL INTERFACE IMPACTS PLANT GROWTH, AGRICULTURAL SUSTAINABILITY, AND RESISTANCE TO GLOBAL CHANGE. THE PROJECT TEAM IS UNIQUELY SUITED TO THIS CHALLENGE WITH EXPERTISE IN TRACE GAS SENSING, SUBSURFACE PROBE DEVELOPMENT AND DEPLOYMENT, SOIL BIOGEOCHEMISTRY, MICROBIAL ECOLOGY AND REACTIVE TRANSPORT MODELING.