LOCATION CONALB TXEstablished Series
TAXONOMIC CLASS: Coarse-silty, carbonatic, hyperthermic Fluventic Haplustepts
TYPICAL PEDON: Conalb loam--cropland. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 6 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; weak fine subangular blocky structure; hard, friable; common fine roots; common wormcasts; few termite or worm tunnels; 1/4 inch crust on surface that is fine platy; violently effervescent; moderately alkaline; abrupt smooth boundary. (4 to 14 inches thick)
Bw1--6 to 12 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; weak fine and medium subangular blocky structure; hard, friable; common fine roots; common wormcasts; few termite or worm tunnels; few fine streaks and films of lighter colored loam; violently effervescent; moderately alkaline; abrupt smooth boundary. (5 to 10 inches thick)
Bw2--12 to 18 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; weak fine and medium subangular blocky structure; hard, friable; few fine roots; root channels and fine pores; few termite or worm tunnels; common wormcasts; few fine streaks and films of lighter colored loam; violently effervescent; moderately alkaline; abrupt smooth boundary. (5 to 12 inches thick)
BC--18 to 38 inches; pale brown (10YR 6/3) loam, brown (10YR 5/3) moist; weak medium subangular blocky structure; hard, friable; few fine roots; old root channels and fine pores; few termite or worm tunnels; few wormcasts of slightly darker color; has few strata to 1/2 inch thick of darker loam and silt loam; violently effervescent; moderately alkaline; diffuse smooth boundary. (12 to 24 inches thick)
C--38 to 64 inches; very pale brown (10YR 7/3) very fine sandy loam, brown (10YR 5/3) moist; massive; hard, friable; weakly stratified in upper part becoming more stratified with depth; strata 1/2 inch to 2 inches thick of darker silty clay loam and loam occur 2 inches to as much as 12 inches apart; violently effervescent; moderately alkaline.
TYPE LOCATION: Uvalde County, Texas; 6.5 miles east on Farm Road 1023 from its junction with U. S. Highway 90 which point is about 1 mile east of Uvalde, 300 feet north in cultivated field, 100 feet east of Frio River.
RANGE IN CHARACTERISTICS: Solum thickness above the stratified C horizon ranges from 14 to 36 inches. Carbonates comprise 40 to 70 percent of the whole soil. Average texture of the 10- to 40-inch control section is loam, silt loam, or clay loam with clay content ranging from 13 to 25 percent. Carbonate clay comprises 2 to about 12 percent.
The A horizon has a hue of 10YR with value ranging from 5 to 6 and chroma of 2 or 3. Moist color values of less than 3.5 are in some pedons where the A horizon is thinner than 7 inches. Texture is loam, silt loam, or fine sandy loam.
The Bw horizon ranges in hue of 10YR and 7.5YR with value of 5 through 7, and chroma of 3 and 4. It is loam, silt loam, or clay loam. A few films and threads of calcium carbonate occur in some pedons.
The BC and C horizon ranges in hue of 7.5YR and 10YR with value of 6 and 7, and chroma of 3 and 4. Stratification is weakly to moderately expressed. Some pedons have gravelly strata or fine sandy loam strata below a depth of 42 inches.
COMPETING SERIES: There are no other series in this family. Competing series are Atco, Guadalupe, Lagloria, McAllen, Reynosa, Rio Grande, Sabenyo, and Winterhaven. Atco, McAllen, and Sabenyo soils lack stratification within a depth of 50 inches. In addition, Atco and Guadalupe soils are coarse-loamy. Guadalupe, Lagloria, and Reynosa soils have mixed mineralogy. In addition, Reynosa and Winterhaven soils are fine-silty. Rio Grande soils lack a cambic horizon and have mixed mineralogy.
GEOGRAPHIC SETTING: Conalb soils are on nearly level to gently sloping areas in flood plains of streams that drain limestone areas. These soils formed in calcareous loamy alluvium. These soils flood about once every third or fourth year in the lower parts of the flood plain and as rarely as once in ten or fifteen years in the higher parts of the flood plain. The soil formed in slightly altered stratified loamy sediments high in lime and several feet thick. The climate is semiarid to subhumid. Mean annual precipitation ranges from 20 to 30 inches, and mean annual air temperature ranges from 70 to 72 degrees F. Thornthwaite annual P-E indices range from 25 to 44. Frost free days range from 240 to 280 days and elevation ranges from 500 to 950 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Atco, Sabenyo and Winterhave series of the competing series and the Dev and Divot series. Atco, Sabenyo, and Winterhaven soils occur at slightly higher elevations. Dev and Divot soils have mollic epipedons. In addition, Dev soils are skeletal and Divot soils are more clayey throughout. Dev soils occur at lower elevations. Divot soils occur in positions similar to Conalb soils.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: Mostly rangeland but considerable acreage is used for irrigated cropland of truck crops, corn, grain sorghum, cotton, and introduced grasses. The native vegetation consists of about 15 percent trees and woody plants of mainly elm, liveoak, pecan, hackberry, and a few large mesquite trees with an understory of redominantly mid and a few short grasses such as fourflower trichloris and bristlegrass. As retrogression occurs, woody vegetation and underbrush increase. Typical increases and decreases are mesquite, whitebrush, spiny hackberry, hooded windmillgrass, curley mesquitegrass, bermudagrass, and annual forbs.
DISTRIBUTION AND EXTENT: Northern Rio Grande Plain of Texas. The series is of moderate extent, probably about 50,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Uvalde County, Texas; 1970. REMARKS: Conalb soils would have been classified in the Alluvial great soil group. This series includes some of the soils that were mapped as Blanco in the past.
ADDITIONAL DATA: National Soil Survey Laboratory Data on S79TX507-2 (79P1728-1732)
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 6 inches (Ap horizon)
Cambic horizon - 6 to 18 inches (Bw1 and Bw2 horizons)