RESEARCHERS ARE CHALLENGED WITH DEVELOPING AGRICULTURAL SYSTEMS THAT USE LIMITED RESOURCES EFFECTIVELY WHILE IMPROVING PRODUCTION IN THE FACE OF LAND DEGRADATION AND INCREASED CLIMATE VARIABILITY. THIS IS ESPECIALLY CRITICAL IN SEMI-ARID SYSTEMS THAT ARE VULNERABLE TO SOIL EROSION, NUTRIENT DEPLETION, AND EXTREME WATER SCARCITY. A SUSTAINABLE AND ECONOMICALLY FEASIBLE MANAGEMENT OPTION IS CONVERTING HIGH-INPUT ROW CROP SYSTEMS TO GRAZED PERENNIAL GRASSLANDS. THESE ARE MANAGED TO PROVIDE HIGH-QUALITY FORAGE FOR ANIMAL PERFORMANCE WHILE IMPROVING SOIL HEALTH AND CONSERVING WATER AND NUTRIENT RESOURCES BY MINIMIZING DISTURBANCE AND ADDING CONTINUOUS SOIL COVER. ENTERIC METHANE (CH4) PRODUCTION FROM CATTLE IS A POTENTIAL SUSTAINABILITY TRADEOFF IN THESE SYSTEMS, BUT IT IS LIKELY POSSIBLE TO OFFSET THESE IMPACTS THROUGH INTEGRATED SOIL-PLANT-ANIMAL MANAGEMENT. PRELIMINARY DATA FOR OUR STUDY INDICATES THAT ADDING LEGUMES CAN BOTH INCREASE SOIL MICROBIAL UPTAKE OF CH4 AND IMPROVE FORAGE QUALITY FOR LIVESTOCK IN SEMI-ARID PASTURES, WHICH IMPROVES RESOURCE EFFICIENCY, SUSTAINABILITY, AND PRODUCTIVITY. OUR PROJECT USES LONG-TERM FORAGE TREATMENTS IN GRAZED SEMI-ARID PASTURES TO DETERMINE HOW MANAGEMENT REGULATES SOIL GREENHOUSE GAS (GHG) FLUXES. THROUGH GREENHOUSE MANIPULATIONS AND FIELD MEASUREMENTS, WE INVESTIGATE HOW NUTRIENT AND FORAGE MANAGEMENT INCREASES SOIL CH4 UPTAKE WHILE IMPROVING SOIL HEALTH IN SEMI-ARID PASTURES. WE ALSO USE SOIL DATA FROM THIS STUDY ALONG WITH PAIRED PLANT AND ANIMAL PRODUCTIVITY DATA FROM THIS LONG-TERM SITE TO MODEL GHG DYNAMICS UNDER DIFFERENT MANAGEMENTS AND ENVIRONMENTAL SCENARIOS. THE RESULTS OF OUR STUDY WILL ULTIMATELY HELP US CREATE MORE EFFICIENT AND RESILIENT SEMI-ARID AGRICULTURAL SYSTEMS ACROSS THE GLOBE.