LOCATION COBB TX+OKEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, thermic Typic Haplustalfs
TYPICAL PEDON: Cobb fine sandy loam, in a cultivated field. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; reddish brown (5YR 4/3) fine sandy loam, dark reddish brown (5YR 3/3) moist; weak fine subangular blocky structure; hard, very friable; few fine roots; slightly acid; gradual smooth boundary. (3 to 12 inches thick)
Bt1--8 to 22 inches; reddish brown (5YR 4/4) sandy clay loam, dark reddish brown (5YR 3/4) moist; weak coarse prismatic structure parting to weak medium subangular blocky; very hard, friable; few fine roots; few fine pores; slightly acid; clear wavy boundary. (8 to 18 inches thick)
Bt2--22 to 30 inches; reddish brown (5YR 5/4) sandy clay loam, reddish brown (5YR 4/4) moist; weak coarse prismatic structure parting to weak medium subangular blocky; very hard, friable; neutral; abrupt irregular boundary. (6 to 18 inches thick)
Cr--30 to 60 inches; weakly cemented reddish sandstone with common distinct coatings of calcium carbonate in the fissures or crevices; neutral.
TYPE LOCATION: Foard County, Texas; from the intersection of Texas Highway 6 and U.S. Highway 70 in Crowell; 1.5 miles west on U.S. Highway 70; 0.3 mile north on county road; 0.2 mile west in cropland. (Latitude: 33N, 59, 28; Longitude: 99W, 45, 15); ? topographic quadrangle; NAD 83.
RANGE IN CHARACTERISTICS:
Particle-size control section (weighted average)
Clay content: 18 to 35 percent
CEC/clay ratio: 0.4 to 0.6
Soil Moisture: A typic-ustic soil moisture regime.
Depth to paralithic contact: 20 to 40 inches
Thickness of the solum, 20 to 40 inches
Base saturation ranges from 75 to 100 percent throughout the argillic horizon.
A Horizon
Hue: 5YR or 7.5YR
Value: 4 to 6 (3 to 5 moist)
Chroma: 4 to 6 (3 to 5 moist)
Texture: Fine sandy loam or loamy fine sand
Clay content: 6 to 18 percent
EC (dS/m): 0 to 2
Effervescence: Noneffervescent
Reaction: Slightly acid or neutral
Bt Horizon
Hue: 2.5YR or 5YR
Value: 4 to 6 (3 to 5 moist)
Chroma: 4 or 6
Texture: Typically sandy clay loam or clay loam, but includes fine sandy loam in the lower part.
Clay content: 18 to 35 percent
Coarse fragments: Sandstone fragments less than 3 inches in diameter ranges from 0 to 10 percent
Base saturation: 75 to 100 percent
Calcium carbonate equivalent: 0 to 5 percent
EC (dS/m): 0 to 2
Effervescence: Noneffervescent to slightly effervescent
Reaction: Slightly acid to moderately alkaline
BC Horizon (where present)
Hue: 2.5YR or 5YR
Value: 4 to 6 (3 to 5 moist)
Chroma: 4 or 6
Texture: Fine sandy loam, sandy clay loam, or clay loam
Clay content: 10 to 35 percent
Coarse fragments: Sandstone fragments less than 3 inches in diameter ranges from 0 to 10 percent
Calcium carbonate equivalent: 0 to 5 percent
EC (dS/m): 0 to 2
Effervescence: Noneffervescent to slightly effervescent
Reaction: Slightly acid to moderately alkaline
Cr Horizon
Hue: 2.5YR to 10YR
Value: 4 or 5 (3 or 4 moist)
Chroma: 2 to 6
Texture: Extremely weakly to moderately cemented sandstone bedrock
Moist bulk density (g/cc): 1.85 to 2.35
Excavation difficulty: Moderate to high
Identifiable secondary carbonate: Thin coatings of calcium carbonate are in fissures or crevices of most pedons.
Effervescence: Noneffervescent to slightly effervescent
Reaction: Slightly acid to moderately alkaline
COMPETING SERIES: These are the Arnett, Decobb, Grandfield, Grandmore, Honeycreek, Hye, Lou, McKnight, Menard, and Rochelle series.
Arnett, Decobb, Grandfield, and Grandmore series: These soils have solum more than 60 inches thick.
Honeycreek series: These soils are 40 to 60 inches to schist bedrock.
Hye series: These soils have base saturation between 40 and 75 percent in the argillic horizon.
Lou series: These soils have granite bedrock in the upper 10 inches of the paralithic contact.
McKnight series: These soils have a lithologic discontinuity between 20 and 40 inches and depth to bedrock is 40 to 60 inches.
Menard and Rochelle series: These soils have solum more than 60 inches to bedrock. In addition, Rochelle soils have a very gravelly substratum.
GEOGRAPHIC SETTING:
Parent material: Residuum derived from sandstone, mainly of the San Angelo Formation of Permian age.
Landform: Convex ridges and side slopes of ridges.
Slope: 0 to 8 percent
Mean annual air temperature range: 60 to 64 degrees F.
Mean annual precipitation range: 22 to 28 inches
Frost-free period: 200 to 230 days
Elevation: 1000 to 2200 feet
Thornthwaite annual P-E indices: 32 to 44
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Abilene, Bluegrove, Cosh, Decobb, Grandfield, Miles, Rochelle, Spade, Spikebox, Tillman, Tilvern, Vernon, and Westill series.
Abilene series: These soils have a mollic epipedon and are on lower alluvial or footslope positions.
Cosh and Spikebox series: These soils are shallow to sandstone bedrock and are on slightly convex positions higher in the landscape.
Decobb series: These soils are very deep to sandstone and are slightly lower in the landscape.
Grandfield and Miles series: These soils are on slightly lower positions and have developed in loamy, Pleistocene age alluvial sediments.
Rochelle series: These soils are on stream terraces and have gravelly substratum.
Spade series: These soils are in similar positions on the landscape, have a cambic horizon, and are calcareous to the surface.
Tillman and Westill series: These soils have a mollic epipedon, are on slightly lower positions and have developed in red alluvium.
Bluegrove, Tilvern and Vernon series: These soils occupy similar to slightly lower landscape positions and have a fine particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate. Runoff is negligible on slopes less than 1 percent, low on 1 to 5 percent slopes and medium on 5 to 8 percent slopes.
USE AND VEGETATION: Used mainly for rangeland. Native vegetation is mainly grasses such as sideoats grama, blue grama, little bluestem, dropseed, threeawn, Arizona cottontop, and buffalograss. Mesquite trees are the dominant woody plants. A small acreage is farmed. Grain sorghum, cotton, and wheat are the major crops.
DISTRIBUTION AND EXTENT: Central Rolling Red Plains of north and northwestern Texas and southwestern Oklahoma. LRR H; MLRA 78C; large extent
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Washita County, Oklahoma; 1935.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon--0 to 8 inches (A horizon)
Argillic horizon--8 to 30 inches (Bt1 and Bt2 horizons)
Paralithic contact: The contact with 30 at inches. (Cr horizon)
Range Site: Sandy Loam Prairie PE 31-44 (078CY110TX).
Soil Interpretation Record Number: TX0125
Taxonomic version: Soil Taxonomy, Second Edition, 1999
ADDITIONAL DATA: NSSL characterization data from Young County, Texas; S92TX-503-005.