Sorghum [Sorghum bicolor (L.) Moench] is among the most important warm-season forages that is grown in mainly arid and semiarid regions of southeastern Iran. Irrigation water is an energy-intensive input and it is also becoming scarce and costly in this country. Soil application of polymeric materials such as Superab A200 (SAP) can increase soil water storage capacity and increase water use effi ciency (WUE). Th e objective of this study was to investigate the eff ect of diff erent rates of SAP and irrigation regimes on dry matter yield, WUE, and some physiological and yield-related traits of Speedfeed sorghum. Th e experiment was conducted in Zahedan, Iran, during the 2009 and 2010 seasons under limited irrigation regimes (irrigation aft er 40, 60, 80, and 100% crop evapotranspiration = ET c ) and four rates of SAP application (0, 75, 150, and 225 kg ha -1 ). Results indicated signifi cant eff ects of irrigation regimes, SAP levels, and their interaction. Th e analysis for dry matter, WUE, and benefi t/cost ratio showed that applying SAP at 100% ET c had no eff ect on these traits, but in the treatments with water defi cit, it improved all the studied traits of sorghum. With regard to economic analysis, applying 75 kg ha -1 SAP for a decrease in the sorghum's water requirement of as much as 20% is economically justifi ed at moderate water defi cits.