Land use: Almost all this area is in farms and ranches. More than two-fifths, consisting of breaks along the Canadian and Cimarron Rivers and their larger tributaries and areas of sandy soils in the southwest, is range of native grasses and shrubs grazed by beef cattle. About one-third of the area, the smooth uplands, is dry-farmed to winter wheat, grain sorghum, and cotton. 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.
Elevation and topography: Elevation ranges from 800 to 2,000 m, increasing gradually from southeast to northwest. 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.
Climate: 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. Average annual temperature - 13 to 17 C. Average freeze-free period - 130 to 220 days, increasing from north to south and from west to east.
Water: The moderately low and erratic precipitation is the source of water for dry-farmed crops and for range. Perennial streams are few; they fluctuate widely in flow from year to year and are little used for irrigation. Sand and gravel throughout the central and northern parts of the area yield an abundance of ground water. Irrigation water is obtained from wells, but in the central and southern parts withdrawals exceed recharge, and the water table is gradually declining. Some areas formerly irrigated are now dry-farmed.
Soils: Most of the soils are Ustolls and Ustalfs. They are deep, fine, and medium textured and coarse textured. These soils have a mesic or thermic temperature regime, an ustic moisture regime, and mixed or carbonatic mineralogy. The level to gently sloping Paleustolls (Pullman, Olton, Acuff, Sherm, Gruver, Texline, and Dumas series), Argiustolls (Richfield series), Paleustalfs (Amarillo, Dallam, Rickmore, and Spurlock series), and Haplustalfs (Dalhart series) are the principal soils on the uplands. Calciustolls (Portales and Dioxice series), Haplustolls (Ulysses series) and Paleustolls (Mansker, Conlen, Sunray, and Estacado series) are dominant on ridges and on the more sloping parts. Haplustolls (Bippus, Humbarger, and Spur series) are on young valley floors and flood plains of the streams. Pellusterts (Randall and Ness series) are in clayey playa lake basins. Shallow Calciorthids (Potter series), Paleorthids (Pastura series), and Torriorthents (Travessilla series) are on the steep slopes and in the breaks. Paleustalfs (Patricia, Springer, and Brownfield series), Haplargids (Triomas, Faskin, and Jalmar series), Ustipsamments (Tivoli series), and Torripsamments (Penwell series) are deep sandy soils in the southwest. Loamy, shallow to moderately deep soils in the southwest are Calciustolls (Kimbrough series), Paleustolls (Lea, Slaughter, and Stegall series), Paleustalfs (Arvana series), Paleorthids (Blakeney and Conger series), and Paleargids (Douro and Sharvana series).
Potential natural vegetation: This area supports a short grass community characterized by blue grama and buffalograss. Mid grasses such as sideoats grama grow on the more open soils and breaks. Tall grasses such as sand bluestem, little bluestem, and indiangrass grow mixed with shinnery oak and sand sagebrush on the sandy soils. A wide range of perennial forbs grow on the sandier soils and are characterized by dotted gayfeather, pitchersage, sagewort, bushsunflower, and daleas.
(From "Land Resource Regions and Major Land Resource Areas of the United States". United States Department of Agriculture Soil Conservation Service Handbook 296. Dec. 1981. pages 52-53.)