Land use: About one-third of this area is federally owned. Most of the remainder is in farms, ranches, or other private holdings. The federal land is mainly in New Mexico. Two-thirds or more of the total area is in range of low carrying capacity. Less than 1 percent is irrigated. Cotton, cantaloupes, and vegetables are the principal crops. Grain sorghum, alfalfa, and other feed and forage crops are also grown.
Elevation and topography: Elevation ranges from 800 to 1,500 m in basins and valleys, but it is more than 2,600 m in the mountains. Broad desert basins and valleys are bordered by gently sloping to strongly sloping fans and terraces. Steep north-south-trending mountain ranges and many small mesas are in the western part.
Climate: Average annual precipitation-200 to 325 mm. Maximum precipitation is from midspring to midautumn. Average annual temperature-13 to 18 C. Average freeze-free period-200 to 240 days in most of the area but 180 days in the northern ends of the Pecos and Rio Grande valleys.
Water: Scarce surface water and low precipitation are severe limitations to use of the area for range. The Rio Grande and Pecos Rivers and a few of their larger tributaries are the only perennial streams. Water for irrigation generally is obtained from these rivers or from wells. Ground water in deep valley fill provides water for domestic use and for livestock and in places for some irrigation.
Soils: Most of the soils are Argids and Orthids. They are well drained and medium textured and have a thermic temperature regime, an aridic moisture regime, and mixed or carbonatic mineralogy. Deep and moderately deep Haplargids (Berino, Madurez, Mohave, Cacique, and Pyote series), Paleargids (Wickett and Douro series), and Calciorthids (Wink, Reaker, Hoban, Turney, Reagan, and Nickel series) are on uplands, piedmont plains, and dissected terraces. Shallow Haplargids (Lehmans series), shallow Calciorthids (Lozier series), Ustolls (Ector series), and Torriorthents (Holloman series) are on bedrock-controlled uplands. Shallow Paleorthids (Simona, Upton, Conger, Blakeney, Delnorte, and Tencee series) are on mesas, uplands, and terraces. Deep and moderately deep Gypsiorthids (Yesum and Reeves series) are in closed basins. Camborthids (Mimbres series), Natrargids (Hondale series), and Torrerts (Dalby and Verhalen series) are on basin floors. Torrifluvents (Gila, Glendale, and Vinton series) are on the flood plains. Torripsamments (Bluepoint, Penwell, Kermit, and Pintura series) are on hummocky sandy uplands.
Potential natural vegetation: This area supports desert grass-shrub
vegetation. Giant dropseed and mesa dropseed, along with scattered shrubs
such as sand sagebrush and yuccas, grow on the sandier soils. Creosotebush,
tarbush, catclaw, and javalinabush are on gravelly, calcareous foot slopes.
Giant sacaton, vine-mesquite, desertwillow, brickellbush, and mesquite grow
in drainageways and depressions. Juniper, pinyon, scattered ponderosa pine,
and Douglas-fir are on upper mountain slopes.
(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 28-29.)