THE GOAL OF OUR RESEARCH IS TO PROVIDE THE FOUNDATIONAL KNOWLEDGE TO DESIGN MANAGEMENT PRACTICES TO SIGNIFICANTLY INCREASE PHOSPHORUS (P) USE EFFICIENCY IN AGROECOSYSTEMS. OUR PROPOSED WORK OCCURS AT THE INTERSECTION OF TWO BROADLY IMPORTANT AREAS OF RESEARCH: (1) SUSTAINABLE USE OF P FERTILIZERS TO IMPROVE CROP PRODUCTION, AND (2) THE INTERACTIONS OF CARBON (C) WITH SOIL MINERAL SURFACES.THE KEY QUESTION WE ADDRESS IN THIS PROPOSAL IS -- HOW DOES THE WATER-SOLUBLE LIGIN FRACTION OF CROP RESIDUE BIOMASS ALTER P ADSORPTION IN SOILS? OUR PROPOSAL FEATURES FOUR NOVEL ASPECTS: WE ARE INVESTIGATING (1) THE LIGNIN EXTRACTED FROM CROP RESIDUE AND ROOT BIOMASS BECAUSE THE LIGNACEOUS FRACTION IS THE DOMINANT CLASSIFICATION GROUP OF COMPOUNDS PRESENT IN SOLUBLE SOIL ORGANIC MATTER; (2) HOW LIGNIN CHEMICAL COMPOSITION IS AFFECTED BY REACTION WITH REACTIVE OXYGEN SPECIES AS EXPECTED DURING BIO-DECOMPOSITION OF PLANT BIOMASS IN AGROECOSYSTEMS; (3) HOW PLANT-DERIVED LIGNIN AND OXIDIZED LIGNIN DERIVATIVES COMPETE WITH P FOR SORPTION TO FEOOH; AND (4) COMPUTATIONAL CHEMISTRY APPROACHES (DENSITY FUNCTIONAL THEORY CALCULATIONS) TO DETERMINE HOW THE STRUCTURAL FEATURES OF LIGNIN-DERIVATIVES AFFECT THEIR COMPETITIVENESS WITH PHOSPHATE FOR FEOOH ADSORPTION SITES. THIS PROPOSAL COMBINES NOVEL, POWERFUL EXPERIMENTAL AND THEORETICAL APPROACHES TO ASK IMPORTANT ECOSYSTEM QUESTIONS AFFECTING AGRICULTURAL PRODUCTIVITY AND SURFACE WATER QUALITY. OUR TEAM COMPRISES COMPLEMENTARY AREAS OF EXPERTISE (ANALYTICAL MASS SPECTROMETRY, COMPUTATIONAL CHEMISTRY, AND SOIL SCIENCE). WE WILL FOCUS ON CHEMICAL AND BIOLOGICAL PROCESSES THAT ARE THE FOUNDATIONAL FOR SUSTAINABLE AGROECOSYSTEM, PROVIDING DATA TO INFORM PROCESS-BASED ECOLOGICAL MODELS NECESSARY FOR DECISION-MAKING IN A CHANGING ENVIRONMENT.