Nearly one-fifth of the area is irrigated. Wheat and grain sorghum are the major crops south of the Canadian River. Other major crops grown in places where irrigation water is available include soybeans, corn, alfalfa, and vegetables. These smooth high plains are gently sloping, but along the major rivers, breaks are very steep. The deep sand in the southwest has an irregular dune topography.
Local relief is in meters, but the major valleys are tens of meters below the general level.
Average annual precipitation - 375 to 550 mm, but it fluctuates widely from year to year. Maximum precipitation is from late in spring through autumn. The low precipitation in winter is mainly snow. The moderately low and erratic precipitation is the source of water for dry-farmed crops and for range. Sand and gravel throughout the central and northern parts of the area yield an abundance of ground water.