Global water resources are under increasing pressure, and some regions face the need to retire irrigation due to groundwater depletion or to meet governmental regulations. In arid and semiarid climates, irrigated lands tend to have more soil organic carbon (SOC) than non-irrigated croplands. However, little is known about how SOC might change following irrigation retirement. Our objective was to quantify changes in SOC and nitrogen stocks after irrigation retirement in semiarid agroecosystems of the High Plains. We sampled fields that stopped using irrigation and transitioned into either dryland crops or ungrazed perennial grasslands and compared SOC and nitrogen stocks in these fields with still irrigated and long-term dryland situations. © 2023 Elsevier B.V.