LOCATION TEXON TX
Established Series
WCC-RD-CLN
03/2012
TEXON SERIES
The Texon series consists of very deep, well drained, moderately slowly permeable soils that formed in eolian sediments overlying marl and limestone of the Cretaceous-age Buda Limestone Formation. These nearly level to gently sloping soils are on plain surfaces of the Edwards Plateau. Slopes range from 0 to 3 percent. Mean annual air temperature is about 64 degrees F, and mean annual precipitation is about 19 inches.
TAXONOMIC CLASS: Fine, smectitic, thermic Torrertic Calciustolls
TYPICAL PEDON: Texon silt loam--rangeland (Colors are for dry soils unless otherwise stated)
A--0 to 2 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate very fine and fine subangular blocky and granular structure; slightly hard, friable; common fine and very fine roots; few fine tubular pores; slightly effervescent; moderately alkaline; gradual smooth boundary. (1 to 4 inches thick)
Bw--2 to 9 inches; brown (7.5YR 4/2) silty clay, dark brown (7.5YR 3/2) moist; moderate fine and medium subangular blocky structure; very hard, firm; common fine and very fine roots; few fine and medium tubular pores; few weathered limestone pebbles; few shell fragments; few wormcasts; slightly effervescent; moderately alkaline; gradual smooth boundary. (5 to 12 inches thick)
Bss1--9 to 18 inches; brown (7.5YR 5/4) silty clay, brown (7.5YR 4/4) moist; weak coarse prismatic structure parting to moderate fine and medium angular blocky; very hard, very firm; few fine roots; few distinct continuous pressure faces on vertical and horizontal surfaces of peds; few distinct slickensides; few weathered limestone pebbles; slightly effervescent; moderately alkaline; gradual smooth boundary. (6 to 20 inches thick)
Bss2--18 to 24 inches; brown (7.5YR 5/4) clay, brown (7.5YR 4/4) moist; weak coarse prismatic structure parting to moderate fine and medium angular blocky; very hard, very firm; few fine roots; common very dark grayish brown (10YR 3/2) soil material in filled cracks and along ped surfaces; few distinct pressure faces on vertical and horizontal surfaces of peds; few distinct slickensides; few weathered limestone pebbles; slightly effervescent; moderately alkaline; gradual wavy boundary. (0 to 10 inches thick)
Bkss--24 to 34 inches; light brown (7.5YR 6/4) clay, brown (7.5YR 5/4) moist; weak coarse prismatic structure parting to weak fine and medium angular blocky; very hard, firm; few fine roots; few distinct slickensides; common concretions and masses of calcium carbonate; violently effervescent; moderately alkaline; gradual wavy boundary. (6 to 16 inches thick)
Bk1--34 to 46 inches; pink (7.5YR 7/4) clay, brown (7.5YR 5/4) moist; weak fine and very fine subangular blocky structure; hard, firm; few fine roots; few fine tubular pores; about 15 percent limestone cobbles; common masses of calcium carbonate; violently effervescent; moderately alkaline; clear wavy boundary. (8 to 20 inches thick)
Bk2--46 to 80 inches; white (10YR 8/1) clay, very pale brown (10YR 8/2) moist; massive; slightly hard, friable; violently effervescent; moderately alkaline.
TYPE LOCATION: Crockett County, Texas; from the intersection of Business Loop 466 and Texas Highway 163 in Ozona; 14.4 miles north on Texas Highway 163; 4.6 miles west on U. S. Highway 190; 0.9 mile north on ranch road; 80 feet east in rangeland. (Latitude: 30N, 55, 24; Longitude: 101W, 14, 15)
RANGE IN CHARACTERISTICS: Solum thickness is 72 to more than 80 inches. The mollic epipedon ranges from 7 to 12 inches thick. The soil, when dry, has cracks 1/2 to 2 inches wide that extend from the surface to a depth of about 24 to 36 inches. The 10 to 40-inch particle-size control section is silty clay or clay containing 40 to 60 percent total clay. Silicate clay content ranges from 35 to 45 percent. Linear extensibility ranges from 6 to 10 cm in the upper 100 cm of the pedon. Reaction is moderately alkaline throughout the pedon. Calcium carbonate equivalent ranges from 10 to 30 percent in the upper 40 inches of the solum and from 30 to 75 percent below 40 inches.
The A horizon has hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 2 to 3. Texture is silt loam or silty clay loam. Effervesence is slight to strong.
The Bw horizon has hue of 7.5YR or 10YR, value of 3 to 5, and chroma of 2 to 3. Texture is silty clay loam or silty clay. Effervesence is slight to strong.
The Bss horizons have a hue of 7.5YR or 10YR, value of 3 to 6, and chroma of 2 to 4. Texture is silty clay loam, silty clay, or clay. Distinct or prominent pressure faces and slickensides are in these horizons. Effervescence is slight to strong.
The Bkss horizon has hue of 5YR or 7.5YR, value of 4 to 6, and chroma 4 and 6. Texture is silty clay loam, silty clay or clay. Effervescence is strong to violent.
The Bk horizons have hue of 5YR or 7.5YR, value of 5 to 8, and chroma 1 to 8. Texture is silty clay loam, silty clay, or clay. Effervescence is violent.
Some pedons are underlain by an R horizon below a depth of 72 inches. The R horizon is indurated limestone.
COMPETING SERIES: There are no other series in this family. Similar soils include
Knippa,
Mosheim,
Rioconcho,
Rowena, and
Valera soils. All of these soils are in more moist climates. Also, Mosheim soils have limestone bedrock at a depth of 40 to 60 inches. Knippa and Rowena soils have mixed minerology. Rioconcho soils have mixed mineralogy and do not have a calcic horizon within 39 inches. Valera soils have a petrocalcic horizon and hard limestone bedrock at a depth of 20 to 40 inches.
GEOGRAPHIC SETTING: Texon soils are on nearly level to gently sloping plains of the Edwards Plateau. Slopes are usually less than 1 percent, but range up to 3 percent. The soil formed in calcareous silty and clayey sediments over marl and limestone of the Cretaceous-age Buda Limestone Formation. Mean annual precipitation ranges from 16 to 22 inches. Mean annual air temperature ranges from 63 to 67 degrees F. The frost-free season ranges from 210 to 240 days. Elevation ranges from 2,000 to 2,700 feet. The Thornthwaite P-E index ranges from 24 to 32.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Ector,
Irion,
Noelke,
Ozona,
Tarrant and
Tobosa soils. Ector and Tarrant soils are higher on the landscape and are underlain by hard limestone bedrock at a depth of 20 inches or less. Ozona soils are on the same position and have a petrocalcic horizon layer between 10 and 20 inches. Noelke and Ozona soils are mapped in a complex with Texon soils in some areas. Irion and Tobosa soils are in slightly lower, concave positions and are vertisols.
DRAINAGE AND PERMEABILITY: These soils are well drained. Permeability is moderately slow. Runoff is low on 0 to 1 percent and medium on 1 to 3 percent slopes.
USE AND VEGETATION: Used mostly for rangeland. Native grasses are buffalograss, scattered patches of tobosa, silver bluestem, sideoats grama, Texas wintergrass, and three-awns. Woody vegetation include mesquite, red berry juniper, agarito, lotebush, ephedra and scattered tasajillo. Forbs include croton, desert holly, and mat spurge.
DISTRIBUTION AND EXTENT: Western Edwards Plateau of Texas (MLRA 81A). This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES PROPOSED: Crockett County, Texas; 2001. The name is from a nearby historic oil field town in Reagan County.
REMARKS: The Texon series was formerly included with the Valera series.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 9 inches (A and Bw horizon)
Calcic horizon - 24 to 80 inches (Bkss, Bk, and BCk horizon), calcareous throughout the pedon.
Vertic features - slickensides, pressure faces, and linear extensibility of more than 6 cm in the upper 40 inches of the soil.
ADDITIONAL DATA: TAMU data from type location in Crockett County, TX (S96TX-105-002).
TAXONOMIC VERSION: Soil Taxonomy, 2nd edition, 1999
National Cooperative Soil Survey
U.S.A.