LOCATION TILLMAN TX OKEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Vertic Paleustolls
TYPICAL PEDON: Tillman loam--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; brown (7.5YR 4/3) loam, dark brown (7.5YR 3/3) moist and crushed; moderate fine and medium subangular blocky structure; hard, friable; common fine and medium roots; common fine and medium pores; few worm casts and channels; few fine siliceous pebbles; slightly acid; clear smooth boundary. (4 to 16 inches thick)
Bt1--4 to 12 inches; reddish brown (5YR 4/3) clay loam, dark reddish brown (5YR 3/3) moist and crushed; weak fine subangular blocky structure; very hard, firm; common fine and medium roots; common fine and medium pores; few worm casts and channels; few faint clay films on surface of peds; few fine siliceous pebbles; neutral; clear smooth boundary. (6 to 12 inches thick)
Bt2--12 to 18 inches; reddish brown (5YR 4/3) clay, dark reddish brown (5YR 3/3) moist; moderate medium prismatic structure parting to moderate fine and medium angular blocky; very hard, very firm; common fine roots; few worm casts and channels; common distinct clay films on surfaces of prisms; few fine black concretions; reversible trans-horizon cracks extend through lower boundary; slightly alkaline; gradual smooth boundary. (6 to 12 inches thick)
Bt3--18 to 28 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; strong coarse angular blocky structure parting to moderate medium angular blocky; extremely hard, very firm; few fine roots, mainly between peds; few worm channels; common distinct clay films on surfaces of peds are one chroma darker than soil matrix; common fine and medium concretions of calcium carbonate; few black masses and fine concretions; reversible trans-horizon cracks extend through lower boundary; noneffervescent; moderately alkaline; gradual wavy boundary. (10 to 20 inches thick)
Btk1--28 to 47 inches; yellowish red (5YR 5/6) clay, yellowish red (5YR 4/6) moist; moderate coarse prismatic structure parting to moderate medium angular blocky; extremely hard, very firm; few fine roots; common distinct dark reddish brown (2.5YR 3/3) clay films on surfaces of peds; common fine and medium concretions of calcium carbonate; few black masses and fine concretions; reversible trans-horizon cracks extend through lower boundary; strongly effervescent; moderately alkaline; diffuse wavy boundary. (8 to 20 inches thick)
Btk2--47 to 74 inches; red (2.5YR 5/6) clay loam, red (2.5YR 4/6) moist, yellowish red (5YR 4/6); moderate medium prismatic structure parting to medium angular blocky; very hard, very firm; few fine roots; few fine pores; common distinct weak red (10R 4/3) clay films on surfaces of prisms; common fine and medium concretions of calcium carbonate; common black masses and few fine black concretions; strongly effervescent; moderately alkaline; diffuse smooth boundary. (12 to 30 inches thick)
BCk--74 to 88 inches; red (2.5YR 5/6) clay loam, red (2.5YR 4/6) moist; weak coarse prismatic structure; very hard, very firm; few fine roots; few dark clay films on surfaces of prisms; soil weathering mainly confined to prism faces, becomes massive toward center of prisms; few fine and medium concretions of calcium carbonate; few fine siliceous pebbles; few black masses and fine concretions; strongly effervescent; moderately alkaline; diffuse smooth boundary. (0 to 18 inches thick)
Cd--88 to 106 inches; red (2.5YR 5/6) dense clay loam, red (2.5YR 4/6) moist; massive; very hard, very firm; weakly stratified and fractured; few reddish brown coats on faces of fractures; common reddish brown (2.5YR 5/4) clay masses; few fine and medium concretions of calcium carbonate; few fine black concretions; few fragments of claystone; few fine siliceous gravel; strongly effervescent; moderately alkaline.
TYPE LOCATION: Wilbarger County, Texas; from the intersection of Farm Road 433 and U. S. Highway 70 in Lockett; 3.6 miles southwest on U. S. Highway 70; 5.0 miles south on Farm Road 1207; 0.05 mile west on county road, 4.9 miles south, 0.1 mile southwest, 5.3 miles southeast and south to gate to fenced enclosure and 160 feet east from gate into rangeland enclosure. Latitude: 33 degrees, 53 minutes, 15 seconds N; Longitude 99 degrees, 19 minutes, 26 seconds W; USGS Santa Rosa Lake, Texas quadrangle; NAD 1927
RANGE IN CHARACTERISTICS:
Particle-size control section (weighted average):
Clay content: 35 to 50 percent clay
Coarse fragments: 0 to 5 percent
CEC/clay ratio: 0.6 or more
Thickness of the solum: 60 to more than 80 inches over dense clay or clay loam, or claystone
Thickness of the mollic epipedon: 10 to 20 inches and usually extends into the argillic horizon
Depth to secondary calcium carbonate: 0 to 24 inches
Depth to a calcic horizon (where present): more than 40 inches
Depth of cracks: more than 2 feet deep
COLE; more than 0.06 in the upper 40 inches
Some pedons have a few siliceous gravel or cobbles on the surface
A Horizon
Hue: 5YR or 10YR
Value: 3 to 5
Chroma: 2 or 3.
Texture: loam, silt loam, silty clay loam, or clay loam
Clay content: 18 to 35 Percent, but averages 30 percent or less
Calcium carbonate equivalent: 0 to 2 percent
EC (dS/m): 0 to 2
SAR: 0 to 1
Effervescence: noneffervescent to slightly effervescent
Reaction: slightly acid to moderately alkaline (6.1 to 8.4)
Bt Horizon
Hue: 2.5YR or 5YR
Value: 3 to 5
Chroma: 2 to 6; with 5 or more in some part of the horizon
Texture: clay loam, silty clay loam, silty clay, or clay
Some pedons have a few slickensides
Calcium carbonate equivalent: 0 to 5 percent
Identifiable secondary carbonate: none to a few fine or medium concretions
EC (dS/m): 0 to 2
Gypsum: 0 to 1 percent
SAR: 0 to 2
Effervescence: noneffervescent to strongly effervescent
Reaction: slightly alkaline or moderately alkaline (7.4 to 8.4)
Btk Horizon
Hue: 2.5YR or 5YR
Value: 3 to 5
Chroma: 4 to 6; with 5 or more in some part of the horizon
Texture: clay loam, silty clay loam, silty clay, or clay
Some pedons have a few slickensides
Calcium carbonate equivalent: 5 to 30 percent
Identifiable secondary carbonate: few to many, fine to coarse, concretions, films, threads, or masses
EC (dS/m): 0 to 8
Gypsum: 0 to 2 percent
SAR: 0 to 12
Effervescence: strongly effervescent to violently effervescent
Reaction: moderately alkaline (7.9 to 8.4)
BCk or 2BCk Horizon
Hue: 2.5YR or 5YR
Value: 3 to 5
Chroma: 4 to 6
Texture; clay loam, silty clay loam, silty clay, or clay
Calcium carbonate equivalent: 2 to 20 percent
Identifiable secondary carbonate: few to many, fine to coarse, concretions, films or masses
EC (dS/m): 0 to 8
Gypsum: 0 to 2 percent
SAR: 0 to 12
Effervescence: slightly effervescent to violenty effervescent
Reaction: slightly alkaline or moderately alkaline (7.4 to 8.4)
C or 2C Horizon
Color: in shades of red, brown, gray, or green
Texture: clay loam, silty clay loam, silty clay, clay, or weakly consolidated claystone
Calcium carbonate equivalent: 1 to 10 percent
EC (dS/m): 0 to 8
Gypsum: 0 to 2 percent
SAR: 0 to 12
Effervescence: very slightly effervescent to strongly effervescent
Reaction: slightly alkaline or moderately alkaline (7.4 to 8.4)
COMPETING SERIES: There are no competing series in the same family. Similar soils are the Agra, Deandale, Hollister, Renfrow, Sagerton, Westill, and Wichita series. Agra and Renfrow soils have secondary carbonates below a depth of 24 inches and are moist for longer periods of time. Deandale and Hollister soils have a mollic epipedon more than 20 inches thick and have smectitic mineralogy. Sagerton soils have a distinct calcic horizon and do not have vertic properties. Westill soils have sola less than 60 inches thick and have developed mainly in the Blaine Formation of Permian age. Wichita soils have an ochric epipedon.
GEOGRAPHIC SETTING: Tillman soils are on alluvial plains and alluvial plain remnants. Slope gradients are mainly less than 2 percent but some areas range to 5 percent. The soil formed in alluvium from redbed clay and claystone mainly of the Clear Fork Group of Permian age. The mean annual precipitation ranges from 23 to 28 inches. The mean annual temperature ranges from 57 to 65 degrees F. Frost free days range from 185 to 230 days, and elevation ranges from 1,000 to 2,000 feet. The Thornthwaite annual P-E indices ranges from 33 to 44.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the similar Deandale, Hollister, Tilvern, Vernon, and Wichita series which are on slightly lower landscape positions. Tilvern and Vernon soils, which are higher in the landscape, have an ochric epipedon and have sola less than 60 inches thick.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow. Runoff is medium on slopes less than 1 percent and high on 1 to 5 percent slopes.
USE AND VEGETATION: Mainly in cropland with small grains, cotton, and sorghums grown. Native vegetation is mainly buffalograss, grama grasses, vine mesquite, Texas wintergrass, prickly pear and mesquite.
DISTRIBUTION AND EXTENT: Rolling Limestone Prairie (MLRA 78D) and Eastern Part of the Central Rolling Red Plains (MLRA 78C) of northwest Texas and western Oklahoma. Extent is large.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Tillman County, Oklahoma; 1932.
REMARKS: Classification is changed from Typic Paleustolls to Vertic Paleustolls 4/2000 based on data from several pedons. Also the series is being restricted to soils that are very deep to redbed claystone. Soils formerly mapped in the Tillman series on the Blaine Formation will be included mostly with the Westill series, which is deep to redbed claystone.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 18 inches (A, Bt1, and Bt2 horizons).
Argillic horizon - 4 to 74 inches (Bt and Btk horizons).
Pale feature - Clay content does not decrease by as much as 20 percent from the maximum within 60 inches with chroma of 5 or more in some part of the argillic horizon.
The assignment of the cation-exchange activity class is based on lab data from several pedons.
Range Site: Clay Loam - 078CY096TX
ADDITIONAL DATA: NSSL data, Lab. Nos. 67L538 - 67L543; 67L772, February 1968, and S96OK-065-003.
TAXONOMIC VERSION: Soil Taxonomy, Second Edition, 1999.