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Development, of sustainable agronomic practices and increasing crop water use efficiency (WUE) under the realm of water scarcity and climate change have become the major focuses in the semiarid Loess Plateau region of China. This 7-yr (2001-2007) study investigated the effects of conservation tillage practices and residue management on crop yield, WUE, soil organic carbon (SOC), soil water storage, economic return, and determined the contribution of various environmental factors on crop WUE under a two-year cycle spring maize (Zea mays L.) winter wheat (Triticum aestivum L.)-summer soybean (Glycine max L.) rotation cropping system. Treatments included conventional tillage (T) as control, conventional tillage followed by straw mulching (TS), no tillage (NT) and no tillage followed by straw mulching (NTS). Averaged over years and species, the overall crop yield was greatest under TS treatment, which was 17 9 and 5% significantly greater than NT, T and NTS treatments, respectively. Additionally, TS treatment resulted in comparable or greater crop WUE than other treatments starting from 2004. Soil moisture storage was not significantly affected by treatments but varied greatly across different soil depths throughout the growing season. Soil organic carbon was significantly increased by straw mulching treatments (NTS and TS) beginning at 2004. In all, NTS treatment provided the greatest economic return on a system basis. Our simulation modeling results indicated that biomass and net radiation are the most important factors in determining WUE in the semiarid Loess Plateau of China.