Cowpeas were extensively grown in the southern U.S. for use as cover crops, seasonal forage, or green manure before the development of inorganic N fertilizers. Cowpeas are excellent warm season cover crops and well adapted to subtropical environments, heat, and well-drained soil. The southeastern region is known for well-drained soils which lead to nitrate leaching as well as cattle and forage production. This study aimed to evaluate cowpeas as summer cover crops and green manure and to document cowpea C and N contributions to soil as green manure vs. inorganic N fertilizers.