PHOSPHORUS (P) IS AN ESSENTIAL NUTRIENT FOR ALL LIFE FORMS AND THERE IS NO OTHER SUBSTITUTE FOR P IN SUSTAINING LIFE AND FOOD PRODUCTION. SUCCESSIVE AND OFTEN EXCESSIVE P INPUTS (THAN AGRONOMIC OUTPUT) HAVE RESULTED IN A BUILDUP OF P IN SOIL. VARIOUS ASPECTS OF P CYCLING IN AGRICULTURAL SOILS ARE POORLY UNDERSTOOD AND THIS HAS LIMITED OUR CAPABILITY TO MAKE ANY PREDICTIVE ASSESSMENT ON THE POTENTIAL RISK OF LEACHING OF P FROM THESE SOURCES TO OPEN WATERS. THE OVERARCHING OBJECTIVE OF THE PROPOSED RESEARCH IS TO IDENTIFY CHEMICAL FORMS OF RECALCITRANT AND RESIDUAL P POOLS AND TRACK THEIR TRANSFER AND TRANSFORMATION IN SOILS. THIS PROJECT WILL APPLY CONVENTIONAL METHODS IN SOIL CHEMISTRY INCLUDING ELEMENTAL AND MINERALOGICAL, MICROSCOPIC, AND SPECTROSCOPICMETHODS TO BETTER RESOLVE SOIL P PROCESSES AND INTEGRATION OF MULTI-SCALE RESEARCH RESULTS FROM FIELD-SIMULATED LABORATORY AND FIELD MEASUREMENTS WILL IDENTIFY AS WELL AS CONSTRAIN CHEMICAL FORMS OF RECALCITRANT AND RESIDUAL P POOLS INSOILS. RESULTS FROM THIS RESEARCH WILL BE TRANSFERRABLE TO OTHER COMPARABLE SOIL ENVIRONMENTS AND CONTRIBUTE TO THE GOAL OF MAINTAINING HEALTHY ECOSYSTEMS.