LOCATION HINKLE OK+TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Vertic Natrustalfs
TYPICAL PEDON: Hinkle silt loam--cultivated. (Colors are for dry soil unless otherwise stated.)
Apn--0 to 6 inches; brown (7.5YR 5/4) silt loam, dark brown (7.5YR 3/4) moist; weak fine granular structure moist, massive dry; hard, friable; the upper l/4 inch is a light brown (7.5YR 6/4) vesicular crust; neutral; abrupt smooth boundary. (6 to 9 inches thick)
Btn1--6 to 16 inches; dark brown (7.5YR 4/2) clay, dark brown (7.5YR 3/2) moist; weak coarse prismatic structure parting to moderate medium blocky; very hard, very firm; silt coatings on faces of prisms; clay films on faces of peds; slightly alkaline; clear smooth boundary. (8 to 12 inches thick)
Btnss--16 to 33 inches; dark brown (7.5YR 4/4) clay, dark brown (7.5YR 3/4) moist; moderate medium blocky structure; very hard, very firm; clay films on faces of peds; common distinct slickensides at 20 degree angles; few soft masses of calcium carbonate; many films and spots of salt; slightly effervescent; moderately alkaline; gradual smooth boundary. (10 to 20 inches thick)
Btnkss1--33 to 45 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; weak medium blocky structure; very hard, very firm; patchy clay films on faces of peds; common distinct slickensides at 20 degree angles; common calcium carbonate concretions; common soft masses of calcium carbonate; violently effervescent; moderately alkaline; gradual smooth boundary. (10 to 15 inches thick)
Btnkss2--45 to 60 inches; red (2.5YR 4/6) clay, dark red (2.5YR 3/6) moist; weak fine blocky structure; very hard, very firm; patchy clay films of faces of peds; common distinct slickensides at 20 degree angles; common calcium carbonate concretions; common soft masses of calcium carbonate; violently effervescent; moderately alkaline; gradual smooth boundary. (5 to 20 inches thick)
C--60 to 72 inches; red (2.5YR 5/6) clay, red (2.5YR 4/6) moist; massive; very hard, very firm; moderately effervescent; moderately alkaline.
TYPE LOCATION: Tillman County, Oklahoma; about 7.5 miles east of Frederick; 2,040 feet east and 250 feet north of the southwest corner of sec. 9, T. 2 S., R. 16 W.
RANGE IN CHARACTERISTICS: Solum thickness is 40 to more than 60 inches. Depth to soft powdery secondary lime is 12 to 30 inches. This soil has cracks within 125 cm. of the mineral soil surface that are 5mm. or more wide through a thickness of 30 cm. or more for some time in most years, and slickensides in a layer 15 cm. or more thick that has its upper boundary within 125 cm. of the mineral soil surface; or a linear extensibility of 6.0 or more between the mineral soil surface and a depth of 100 cm. The content of calcium carbonate as soft masses ranges from 2 to 10 percent by volume below a depth of 12 inches.
The A horizon has hue of 5 YR through 10YR, value of 3 through 6 (2 through 5 moist), and chroma of 2 through 4. Texture is loam or silt loam. Reaction ranges from slightly acid through moderately alkaline. This horizon is both hard and massive when dry. Some pedons, in plowed fields after rains, form a surface crust up to 1 inch thick that is 1 to 2 units higher in value than the Ap horizon. The exchangeable sodium percentage ranges from 5 to 25 percent.
The Btn horizon has hue of 5YR through 10YR, value of 4 or 5 (3 or 4 moist), and chroma of 2 through 4. Texture is silty clay loam, clay loam, silty clay, or clay with clay content of 35 to 50 percent. Reaction is slightly or moderately alkaline. This horizon has prismatic or columnar structure which is capped with uncoated silt or sand grains and has tongues of this material which extend more than 2.5 cm. into the horizon; and has an exchangeable sodium percentage of 15 to 25 percent.
The Btnss horizon has hue of 5YR or 7.5YR, value of 4 or 5 (3 or 4 moist), and chroma of 2 through 4. Texture is silty clay, clay, clay loam, or silty clay loam with clay content of 35 to 50 percent. Reaction is slightly alkaline or moderately alkaline. Exchangeable sodium percentage is 15 to 25 percent.
The Btnkss horizons have hue of 2.5YR through 7.5YR, value of 4 through 6 (3 through 5 moist), and chroma of 2 through 6. Texture is clay loam, silty clay loam, silty clay, or clay with clay content of 35 to 50 percent. Reaction is slightly alkaline or moderately alkaline. Exchangeable sodium percentage is 15 to 25 percent. Calcium carbonate content in the form of soft masses ranges from 2 to 10 percent by volume.
The C horizon has hue of 2.5YR or 5YR, value of 4 through 6 (3 through 5 moist), and chroma of 2 through 6. Texture is silty clay loam, clay loam, clay, or silty clay with clay content of 35 to 50 percent. Reaction is slightly alkaline or moderately alkaline.
Some pedons have buried soils below 40 inches that formed in clayey sediments weathered from Permian age shales and clay beds.
COMPETING SERIES: The closely competing Foard series has a mollic epipedon and has an exchangeable sodium percentage that is less than 15 percent in the upper 20 inches (from the soil surface).
GEOGRAPHIC SETTING: Hinkle soils are on nearly level or very gently sloping broad summits and shoulder slopes of terrace pediments in the Central Rolling Red Plains (MLRA-78C) and the Wichita Mountains (MLRA-82B). Slopes are 0 to 3 percent. They occur in roughly circular areas from 20 feet to 300 feet in diameter. These soils formed in clayey material weathered from old alluvium of granitic outwash from the Wichita Mountains. The moisture regime is Typic-Ustic. The temperature regime is thermic. The mean annual precipitation is 22 to 30 inches. The mean annual air temperature is 57 degrees to 63 degrees F. The Thornthwaite annual PE Indices is 33 to 44. The frost free days range from 185 to 230.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the closely competing Foard series and the Hollister, Lawton, and Tillman series. Foard soils are on the same landforms and positions as Hinkle soils. Hollister, Lawton, and Tillman soils have mollic epipedons and lack natric horizons.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is negligible to high. Permeability is very slow.
USE AND VEGETATION: Most areas are used for small grains. Some areas are used for cotton, grain sorghum, tame pasture or rangeland. Native vegetation is mid grasses.
DISTRIBUTION AND EXTENT: Western Oklahoma. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Canadian County, Oklahoma; 1972.
ADDITIONAL DATA: Soil Survey Laboratory, Lincoln, Nebraska. Samples 72L360-61. Montmorillonitic mineralogy.
REMARKS: Soil Interpretation Record: OK0041 Series.
Hinkle soils were formerly correlated as slick spots in recent soil surveys.
Diagnostic horizons and features recognized in this pedon are:
Ochric Epipedon - the zone from the surface of the soil to a depth of 6 inches. (A horizon)
Natric Horizon - the zone from a depth of 6 inches to 60 inches. (Bt horizons)
Vertic feature - This soil has cracks within 125 cm. of the mineral soil surface that are 5 mm or more wide through a thickness of 30 cm or more for some time in most year, and slickensides or wedge-shaped aggregates in a layer 15 cm or more thick that has its upper boundary within 125 cm of the mineral soil surface; or a linear extensibility of 6.0 or more between the mineral soil surface and depth of 100 cm.