Increases in crop production per unit of water used is imperative for supplying adequate food, feed and fiber in an environment where future water supplies are not expected to increase substantially. Field studies indicate that when yield from crops with common development patterns are increased by better crop management, water use efficiency (WUE) is also increased. Increased yields from genetic improvement usually result in an increased WUE with the possible exception where season length is different. Crop simulation models required modifications to reasonably simulate the high yield; new functions for kernel number per ear, for barren plants in a stand, and to account for non-uniformity of stand. Simulated yield response of an old and modern hybrid to a wide range of plant densities and uniformity patterns agreed reasonably well with observations suggesting that plant densities could be increased and uniformly spaced to obtain near maximum yield and WUE for Midwest USA climate. The paper reports an application of the SALUS model which is design to account for management effects on yield and water use efficiency.