LOCATION COLWELL ALEstablished Series
TAXONOMIC CLASS: Fine, kaolinitic, thermic Rhodic Paleudults
TYPICAL PEDON: Colwell loam on a smooth, 1 percent slope in a loblolly pine plantation. (Colors are for moist soil.)
Ap--0 to 6 inches; yellowish red (5YR 4/6) loam; weak coarse subangular blocky structure; friable; many fine roots and common medium and coarse roots; many fine fragments of charcoal; common fine and medium concretions of iron and manganese oxides; very strongly acid; abrupt wavy boundary. (3 to 10 inches thick)
Bt1--6 to 14 inches; dark reddish brown (2.5YR 3/4) clay loam; weak medium subangular blocky structure; friable; common fine and medium roots; common distinct dark red (2.5YR 3/6) clay films on faces of peds; few thin, patchy black coatings of manganese oxide on the faces of peds and in root channels; common fine concretions of iron and manganese oxides; very strongly acid; gradual wavy boundary.
Bt2--14 to 25 inches; dark red (2.5YR 3/6) clay; weak medium subangular blocky structure; firm; common fine roots; common distinct dark reddish brown (2.5YR 3/4) clay films on faces of peds; few fine concretions of iron and manganese oxides; moderately acid; gradual wavy boundary.
Bt3--25 to 40 inches; dark red (2.5YR 3/6) clay; weak medium subangular blocky structure; firm; few fine roots; common distinct dark reddish brown (2.5YR 3/4) clay films on the faces of peds; few fine concretions of iron and manganese oxides; strongly acid; gradual wavy boundary.
Bt4--40 to 56 inches; dark red (2.5YR 3/6) clay; weak medium subangular blocky structure; firm; few fine roots; common distinct dark reddish brown (2.5YR 3/4) clay films on the faces of peds; about 5 percent rounded quartzite pebbles; few fine concretions of iron and manganese oxides; strongly acid; gradual wavy boundary.
Bt5--56 to 81 inches; dark red (2.5YR 3/6) clay; weak coarse subangular blocky structure; firm; few fine distinct clay films on the faces of peds; about 5 percent rounded quartzite pebbles; few fine prominent brownish yellow (10YR 6/6) masses of iron accumulation that are relict redoximorphic features; strongly acid. (Combined thickness of the Bt horizons is more than 60 inches.)
TYPE LOCATION: Hale County, Alabama; about 5.5 miles southwest of Morgan Springs; about 600 feet north and 1,700 feet west of the southeast corner of sec. 28, T. 20 N., R. 6 E.; USGS Morgan Springs, AL topographic quadrangle; Lat. 32 degrees 40 minutes 18 seconds N. and Long. 87 degrees 28 minutes 41 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness is more than 60 inches. Reaction ranges from very strongly acid to moderately acid throughout the profile, except for surface layers that have been limed. Fine, rounded pebbles of quartzite occur in most pedons, but range from 0 to 15 percent throughout. Soft black masses or coatings and/or concretions of iron and manganese oxides are few to common throughout the profile. Base saturation at 50 inches below the top of the argillic by sum of cations is more than 15 percent.
The A or Ap horizon has hue of 2.5YR to 7.5YR, value of 3 or 4, and chroma of 2 to 6. Texture is sandy loam, loam, or sandy clay loam.
A thin AB or BA horizon occurs in some pedons. It has hue of 2.5YR to 7.5YR, value of 3 to 5, and chroma of 4 to 6. Texture is sandy loam, loam, or sandy clay loam.
The upper part of the Bt horizon has hue of 10R or 2.5YR, value of 3, and chroma of 4 to 6. The lower part, below a depth of 30 inches from the upper boundary of the argillic horizon, has a similar range in color as the upper part and in addition includes value of 4. The particle-size control section averages 20 to 40 percent silt and more than 20 percent sand. Texture is clay or clay loam in the upper part and clay, clay loam, or sandy clay in the lower part. Redox accumulations or depletions in shades of brown or yellow range from none to common and are assumed to be relict redoximorphic features.
COMPETING SERIES: These are the Anniston, Beckham, and Decatur series in the same family and the Davidson and Greenville series in a closely related family. Anniston soils formed in alluvium and colluvium derived from sandstone, shale, and quartzite and commonly have angular fragments of sandstone in the profile. Beckham soils formed in residuum from marble and have less than 15 percent base saturation by sum of cations at 50 inches below the top of the argillic horizon. Decatur soils formed in residuum weathered from limestone and have less than 20 percent sand in the particle-size control section. Davidson and Greenville soils have a kandic horizon. Davidson soils formed in residuum weathered from dark-colored rocks of the Piedmont. Greenville soils have less than 20 percent silt in the particle-size control section.
GEOGRAPHIC SETTING: Colwell soils are on uplands and ancient, high terraces of the Gulf coastal plain. Slopes range from 0 to 15 percent, but commonly are less than 8 percent. These soils formed in clayey marine or fluvial sediments. The average annual precipitation ranges from 48 to 60 inches. The average annual air temperature ranges from 63 to 68 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bama, Brantley, Lucedale, Luverne, Smithdale, and Subran soils. Bama and Lucedale soils are in positions similar to those of the Colwell soil on summits of high terraces and are fine-loamy. Brantley, Luverne, and Smithdale soils are on side slopes and do not have rhodic colors in the upper part of the argillic horizon. Additionally, Brantley and Luverne soils have mixed clay mineralogy and Smithdale soils are fine-loamy.
DRAINAGE AND PERMEABILITY: Colwell soils are well drained. Runoff is slow to medium and permeability is moderate.
USE AND VEGETATION: Most of the acreage is in cultivated crops, pasture, or hayland. Common crops include cotton, corn, soybeans, grain sorghum, and wheat. Some areas have been planted to loblolly pine or longleaf pine and a few small areas are in native forest of mixed hardwood and pine.
DISTRIBUTION AND EXTENT: MLRA 133A, Southern Coastal Plain of Alabama and possibly Mississippi. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Auburn, Alabama
SERIES PROPOSED: Hale County, Alabama; 2001
REMARKS: These soils were formerly included with the Greenville series. The name is derived from Colwell Creek in Hale County, Alabama.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from the surface to a depth of 6 inches (Ap horizon).
Argillic horizon - from a depth of 6 inches to 81 inches (Bt horizons).
Rhodic feature - have within the upper 30 inches of the argillic horizon, a hue of 2.5YR or redder, moist value of 3 or less, and dry value no more than 1 unit higher than moist value (Bt1, Bt2, and Bt3 horizons).