LOCATION CASTEPHEN               TX

Established Series
Rev. LEW-RMR-RM
08/2017

CASTEPHEN SERIES

The Castephen series consists of loamy soils that are shallow to a paralithic. These well drained soils formed in calcareous loamy residuum derived from interbedded chalk and marl. These gently to moderately sloping soils are on ridges on dissected plains. Slopes range from 1 to 8 percent. Mean annual precipitation is about 946.4 mm (37.3 in) and the mean annual air temperature is about 19.3 degrees C (66.8 degrees F).

TAXONOMIC CLASS: Loamy, carbonatic, thermic, shallow Entic Haplustolls

TYPICAL PEDON: Castephen silty clay--pastureland. (Colors are for dry soil unless otherwise stated.)

Ap--0 to 20 cm (0 to 8 in); brown (7.5YR 4/2) silty clay, dark brown (7.5YR 3/2) moist; moderate fine granular and moderate fine subangular blocky structure; hard, firm; common fine roots; few fine chalk fragments; violent effervescence; moderately alkaline; clear smooth boundary. (15 to 51 cm [6 to 20 in] thick)

A--20 to 41 cm (8 to 16 in); brown (7.5YR 4/2) silty clay, dark brown (7.5YR 3/2) moist; moderate fine subangular blocky structure; hard, firm; few fine roots; common fine chalk fragments from 0.4 to 8 cm (1/8 to 3 in) in diameter; violent effervescence; moderately alkaline; abrupt smooth boundary. (0 to 25 cm [0 to 10 in] thick)

Cr--41 to 56 cm (16 to 22 in); very pale brown (10YR 7/4) interbedded chalk and loamy marl; moderately alkaline.

TYPE LOCATION: Williamson County, Texas; 1.2 miles east on Farm Road 971 from the intersection of Farm Road 971 and State Highway 418 (Business Route U. S. Highway 81) in Georgetown; 3 miles northeast on county road 152; 300 feet north in pasture.
USGS topographic quadrangle: Weir,TX;
Latitude: 30 degrees, 41 minutes, 55.6 seconds North;
Longitude: 97 degrees, 37 minutes, 16.7 seconds West.
Datum: WGS84

RANGE IN CHARACTERISTICS:

Solum depth: from 20 to 51 cm (8 to 20 in)
Soil Moisture: An ustic soil moisture regime. The soil moisture control section is dry in some or all parts for 90 or more cumulative days per year in normal years.
Soil temperature: 15 to 22 degrees C (59 to 72 degrees F)
Depth to paralithic contact: 20 to 51 cm (8 to 20 in)
Thickness of mollic epipedon: 10 to 51 cm (4 to 20 in)

Particle-size control section:
Clay content: 24 to 43 percent
Silicate clay content: 21 to 35 percent
Rock fragments: amount-2 to 35 percent; kind-chalk; shape-nonflat; size-gravels
Calcium carbonate equivalent: 40 to 70 percent

A horizon
Hue: 7.5YR or 10YR
Value: 3 to 5
Chroma: 1 to 3
Texture: silty clay, silty clay loam, loam, or clay loam
Clay content: 24 to 43 percent with silicate clay ranging from 21 to 35 percent
Rock Fragments: amount-2 to 15 percent; kind-chalk; shape-nonflat; size-gravel

A2 horizon (where present)
Hue: 7.5YR or 10YR
Value: 4 to 6
Chroma: 1 to 3
Texture: silty clay, silty clay loam, loam, or clay loam
Clay content: 24 to 43 percent with silicate clay ranging from 21 to 35 percent
Rock Fragments: amount-2 to 35 percent; kind-chalk; shape-nonflat; size-gravel

Cr horizon:
Hue: 5YR to 10YR
Value: 4 to 8
Chroma: 1 to 3
Chalk interbedded with marl and calcareous loamy residuum
Hardness: less than 3 on Mohs scale and can be cut with a spade when moist

COMPETING SERIES: There are no soils in the same family. Similar soils include the Doss, Real, Stephen, and Whitewright series.
Doss and Real soils: have calcic horizons. In addition, Real soils have more than 35 percent coarse fragments.
Stephen soils: have mixed mineralogy and are in a clayey particle size class.
Whitewright soils: have an ochric epipedon.

GEOGRAPHIC SETTING:
Parent material: interbedded chalk, marl, or soft limestone rubble, mainly of the Austin Chalk Formation
Landscape: dissected plains
Landform: ridges
Slope: 1 to 8; convex and are mostly less than 5 percent, but range up to 8 percent
Mean annual air temperature: 18 to 21 degrees C (64.4 degrees to 69.8 degrees F)
Mean annual precipitation: 737 to 948 mm (29 to 37.3 in)
Frost-free period: 230 to 293 days
Elevation: 190.8 to 366 m (626 to 1201 ft)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar Whitewright series, and the Altoga, Austin, and Eddy series.
Eddy and Whitewright soils: occur on similar surfaces.
Eddy soils: contain more than 35 percent coarse fragments.
Altoga and Austin soils: occur at lower elevations and have sola more than 51 cm (20 in) thick.

DRAINAGE AND PERMEABILITY:
Drainage class: Well;
Permeability class: Moderate;
Runoff: low on slopes of 1 to less than 5 percent and medium on slopes of 5 to 8 percent;

USE AND VEGETATION: Mainly cultivated and used for pasture or small grains. Local areas are range with native vegetation consisting of tall and mid grasses, such as little bluestem, sideoats grama, and hairy grama. Buffalograss and Texas Needlegrass increase in heavily grazed areas.

DISTRIBUTION AND EXTENT: This soil occurs mainly in the Northern Blackland Prairies (MLRA 86A) and Grand Prairies (MLRA 85) of Central Texas. The series is moderately extensive.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: Williamson County, Texas; 1980.

REMARKS: The Castephen series was formerly classified in the Rendzina great soil group and was included in the Stephen and Doss series.

Diagnostic horizons and features recognized in this pedon are:

Mollic horizon: 0 to 41 cm (0 to 16 in) (A horzions)
Paralithic contact: chalk at a depth of 41 cm (16 in) (Cr horizons)
Free carbonates: 0 to 56 cm (0 to 22 in) (Ap, A, and Cr horizons)

ADDITIONAL DATA: None

Taxonomic Version: Keys to Soil Taxonomy, Twelfth Edition, 2014

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National Cooperative Soil Survey
U.S.A.