LOCATION COLBERT AL+KY MD TNEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Vertic Hapludalfs
TYPICAL PEDON: Colbert silt loam on a gently sloping upland under mixed hardwoods at an evaluation of about 565 feet. (Colors are for moist soil.)
A1-- 0 to 3 inches; dark grayish brown (10YR 4/2) silt loam; weak medium granular structure; friable; few fine and medium roots; very strongly acid; clear smooth boundary.
A2--3 to 8 inches; pale brown (10YR 6/3) silt loam; weak medium granular structure; friable; common fine and medium roots; friable; very strongly acid; abrupt smooth boundary. (Combined thickness of the A horizon is 3 to 10 inches)
Bt1--8 to 15 inches; strong brown (7.5YR 5/6) silty clay loam; strong medium angular and subangular blocky structure; firm; thin continuous clay films on faces of most peds; few medium roots; few old cracks filled with brown silt loam; very strong acid; clear smooth boundary.
Bt2--15 to 26 inches; strong brown (7.5YR 5/6) silty clay; few fine distinct light gray (10YR 7/2) and few medium distinct yellowish red (5YR 5/6) mottles; strong coarse angular and subangular blocky structure; very firm, plastic; thin continuous clay films on faces of most peds; few medium roots; few pressure faces; very strongly acid; gradual smooth boundary.
Bt3--26 to 36 inches; yellowish brown (10YR 5/6) clay; common medium distinct light gray (10YR 7/2) and many medium distinct yellowish red (5YR 5/6) mottles; moderate coarse angular and subangular blocky structure; very firm, plastic; thin continuous clay films on faces of peds; few fine roots; few pressure faces; very strongly acid; gradual smooth boundary.
Bt4--36 to 44 inches; mottled yellowish brown (10YR 5/6), light gray (10YR 7/2), and yellowish red (5YR 5/6) silty clay; weak coarse subangular blocky structure; very firm, sticky, and very plastic; thin continuous clay films on faces of peds; few fine roots; common pressure faces, few nonintersecting slickensides; very strongly acid; gradual smooth boundary. (Combined thickness of the Bt horizon is 30 to more than 50 inches.)
C--44 to 55 inches; light olive brown (2.5Y 5/4) clay; many medium distinct gray (N 5/0) and common medium distinct yellowish brown (10YR 5/3) mottles; massive; very firm, sticky, and very plastic; about 2 percent by volume of manganese concretions, and about 2 percent by volume of 2 to 20 mm limestone fragments; common pressure faces; few nonintersecting and intersecting slickensides; neutral. (0 to 20 inches thick)
R--55 inches; limestone bedrock.
TYPE LOCATION: Colbert County, Alabama; 2.7 miles south of the intersection of U.S. Highway 72 and Woodmont Avenue, Tuscumbia, Alabama; on County Road 55; 75 feet north of road; in the SE1/4 NW1/4, sec. 28, T. 4 S., R. 11 W.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 40 to 60 inches and depth to limestone bedrock ranges from 40 to more than 72 inches. Reaction of the A and Bt horizons ranges from very strongly acid to slightly acid. Reaction of the BC, CB, AND C horizons ranges from slightly acid to mildly alkaline.
The A horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 2 to 4. Texture is loam, silty loam, or silty clay loam. Most pedons with silty clay loam A horizons are eroded.
The E horizon, where present, is less than 5 inches thick and has hue of 10YR, value of 5 or 6, and chroma of 2 to 6. Texture is silt loam.
The upper part of the Bt horizon has hue of 7.5YR to 2.5Y, value of 5 to 7, and chroma of 4 to 8. Texture is silty clay loam, silty clay, or clay. The lower part of the Bt horizon has the same hue, value, and chroma range as the upper part of the Bt horizon with few to many mottles in varying shades of red, gray, and brown; or it is mottled in varying shades of yellow, red, gray, and brown. Texture is silty clay or clay.
The C, and, where present, the CB or BC horizon has hue of 7.5YR to 5Y, value of 5 or 6, and chroma of 2 to 8. Texture is silty clay or clay. Nodules of calcium carbonate, manganese concretions, and limestone fragments range from 0 to 5 percent by volume and are 2 to 30 mm in size.
The bedrock is hard limestone. Some pedons have a thin shaly Cr horizon above the bedrock.
COMPETING SERIES: These are Etoile, Kipling, Lorman, Natchitoches, Rayburn, Wilcox, and Woodtell series. Etoile, Kipling, Lorman, Natchitoches, and Woodtell soils are not underlain by bedrock. Rayburn and Wilcox soils are underlain by soft bedrock are are more acid.
GEOGRAPHIC SETTING: Colbert soils are on nearly level to moderately steep uplands of Limestone Valleys. Slopes range from 1 to 25 percent. The soils formed in residuum weathered from agrillaceous limestone or shaly limestone. Average annual temperature is 61 degrees F. and average annual precipitation is 47 inches near the type location.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Barfield, Capshaw, Conasauga, Firestone, Ketona, Talbott, and Tupelo soils. Barfield and Talbott soils are on either slightly higher elevation or adjacent side slopes and have bedrock at a depth of less than 40 inches. Capshaw soils are on similar landforms but have mixed clay mineralogy. Conasauga and Firestone soils are on either slightly higher elevations or adjacent side slopes and are underlain by soft shale bedrock. Ketona and Tupelo soils are on lower landforms, have mixed clay mineralogy, and a shallower seasonal water table.
DRAINAGE AND PERMEABILITY: Moderately well drained; rapid to slow runoff; slow permeability in the upper part and very slow permeability in the lower part. In wet seasons water will perch on the C horizon for short periods.
USE AND VEGETATION: About 40 percent of the soil is cleared and used for pasture and hay. Most other areas are in woodland. Forests are mixed hardwoods and pine. Some areas are used for crops such as corn, cotton, and small grains.
DISTRIBUTION AND EXTENT: Alabama, Georgia, Kentucky, Maryland, and Tennessee. The series is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Colbert County, Alabama; 1908.