Land use: Most of the area is range, but large acreages are cultivated. The range is grazed mainly by beef cattle and wildlife. Grain sorghum, cotton, corn, flax, and small grain for grazing are the main crops. Local areas are irrigated. Hunting leases for deer, quail, and mourning dove are an important source of income. The major concern of management is controlling the brush and cactus that invade the grasslands.
Elevation and topography: Elevation ranges from 25 m in the southeast to 200 m in the northwest. These plains are nearly level but smooth hills and valleys are gently rolling. The valleys are narrow to broad. The hills are mostly in the east.
Climate: Average annual precipitation-625 to 750 mm. Most of the precipitation falls during the growing season. Average annual temperature-21 to 22 C. Average freeze-free period-260 to 310 days.
Water: Rainfall is adequate for range grasses but marginal for cultivated crops. High temperatures and high evaporation and transpiration rates limit crop production. The Nueces River and deep wells provide water for irrigation. Deep wells and ponds provide water for livestock and for domestic use.
Soils: Most of the soils are Ustalfs. They are deep and moderately coarse textured and coarse textured. These soils have a hyperthermic temperature regime, an ustic moisture regime, and mixed mineralogy. Ustolls are also extensive. Gently sloping to undulating Paleustalfs (Floresville, Miguel, Webb, and Wilco series) are on plains. Nearly level to gently sloping Argiustolls (Clareville and Elmendorf series) and Calciustolls (Knippa series) are in broad valleys. Gently sloping to rolling Calciustolls (Olmos and Pettus series) are on hills.
Potential natural vegetation: This area supports open grassland with
scattered mesquite, live oak, and other trees. Little bluestem, sideoats
grama, lovegrass tridens, fourflower trichloris, Arizona cottontop, plains
bristlegrass, and other mid grasses are dominant on the deeper soils. A number
of forbs, including orange zexmania, catclaw sensitivebrier, western indigo,
and bushsunflower grow on these soils. Open grassland with scattered low-growing
brush, such as guajillo, blackbrush, elbowbush, and kidneywood, characterize
the shallower soils. Arizona cottontop, sideoats grama, green sprangletop,
and twoflower trichloris are dominant mid grasses on these soils.
(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. page 57.)