LOCATION OKTIBBEHA AL+AR FL GA LA MS TN
Established Series
Rev. PGM; GRB
12/2014
OKTIBBEHA SERIES
The Oktibbeha series consists of very deep, moderately well drained, very slowly permeable soils that formed in clayey sediments overlying chalk or calcareous clays. They are on convex ridges and side slopes on uplands of the Alabama and Mississippi Blackland Prairie (MLRA 135A) and the Southern Coastal Plain (MLRA 133A) Major Land resource areas. Near the type location, the average annual air temperature is about 63 degrees F. and the average annual precipitation is about 53 inches. Slope ranges from 1 to 30 percent.
TAXONOMIC CLASS: Very-fine, smectitic, thermic Chromic Dystruderts
TYPICAL PEDON: Oktibbeha clay loam in pasture, micro-high of cyclic pedon. (Colors are for moist soil.)
Ap--0 to 4 inches; dark brown (10YR 3/3) clay loam; weak medium subangular blocky structure; firm; many very fine and fine roots; slightly acid; abrupt smooth boundary. (1 to 6 inches thick)
Bt1--4 to 9 inches; yellowish red (5YR 5/6) clay; moderate fine and medium subangular blocky structure; firm; common fine roots and few coarse roots along structural faces; distinct pressure faces on surfaces of peds; very strongly acid; clear wavy boundary.
Bt2--9 to 13 inches; yellowish red (5YR 5/6) clay; weak coarse prismatic structure parting to moderate medium subangular blocky; firm; common fine roots and few coarse roots along structural faces; distinct pressure faces on surfaces of peds; few medium distinct red (2.5YR 5/6) masses of iron accumulation within the matrix; very strongly acid; clear wavy boundary. (Combined thickness of the Bt horizon is 6 to 25 inches.)
Bss1--13 to 34 inches; yellowish brown (10YR 5/6) clay; weak coarse prismatic structure parting to moderate medium subangular blocky; firm; few fine roots throughout; common large intersecting slickensides having distinct polished and grooved surfaces; few fine faint pale brown (10YR 6/3) iron depletions on faces of peds and few medium faint strong brown (7.5YR 4/6) masses of iron accumulation on faces of peds and within the matrix; very strongly acid; clear wavy boundary.
Bss2--34 to 45 inches; yellowish brown (10YR 5/6) clay; weak coarse subangular blocky structure parting to moderate medium subangular and angular blocky; firm; few fine roots on faces of peds and on slickenside faces; common large intersecting slickensides having prominent polished and grooved surfaces; common medium distinct light brownish gray (10YR 6/2) iron depletions on faces of peds and within the matrix; slightly acid; abrupt wavy boundary. (Combined thickness of the Bss horizon is 15 to 35 inches.)
Bkss1--45 to 62 inches; light olive brown (2.5Y 5/4) interior, light brownish gray (2.5Y 6/2) exterior, silty clay; weak very coarse subangular blocky structure parting to strong fine and medium angular blocky; firm; few fine roots, flattened on primary surfaces; common large intersecting slickensides having prominent polished and grooved surfaces; few fine and medium distinct light brownish gray (10YR 6/2) iron depletions in the matrix; olive gray colors on faces of slickensides and peds are iron depletions; many fine and medium rounded soft masses of calcium carbonate and few fine rounded calcium carbonate nodules; violently effervescent; slightly alkaline; clear wavy boundary.
Bkss2--62 to 80 inches; light olive brown (2.5Y 5/6) interior, olive gray (5Y 5/2) exterior, clay; weak very coarse subangular blocky structure parting to strong fine and medium angular blocky; firm; few fine roots, flattened on primary surfaces; common large intersecting slickensides having prominent polished and grooved surfaces; few fine distinct light brownish gray (10YR 6/2) iron depletions in the matrix; olive gray colors on faces of slickensides and peds are iron depletions; many fine and medium rounded soft masses of calcium carbonate; violently effervescent; moderately alkaline.
TYPE LOCATION: Marengo County, Alabama; about 1 mile northeast of Dayton on County Road 44; 1,800 feet south and 1,800 feet east of the northwest corner of section 18, T.16N., R.5E.
RANGE IN CHARACTERISTICS: Depth to horizons with secondary carbonates ranges from 30 to 50 inches. Depth to chalk bedrock characterized as a paralithic contact is more than 60 inches.
The A or Ap horizon has hue of 5YR to 10YR, value of 3 to 5, and chroma of 2 to 4. Texture is commonly clay loam, silty clay loam, clay, or silty clay, but ranges to loam, fine sandy loam, or silt loam. Reaction is commonly very strongly acid or strongly acid, but ranges to neutral where lime has been added.
The Bt horizon has hue of 2.5YR or 5YR, value of 4 to 5, and chroma of 6 to 8. Texture is clay. Iron depletions in shades of gray and iron accumulations in shades of brown and red range from none to common, generally increasing with depth. Reaction ranges from extremely acid to strongly acid. Some pedons have faint, slightly grooved slickensides and are designated Btss.
The upper part of the Bss horizon has hue of 2.5YR to 10YR, value of 4 to 6, and chroma of 4 to 8; or has no dominant matrix color and is multicolored in shades of red, brown, and gray. The lower part has hue of 10YR or 2.5Y, value of 5 or 6, and chroma of 4 to 6; or has no dominant matrix color and is multi-colored in shades of brown, gray, and red. Iron depletions in shades of gray and iron accumulations in shades of brown and red range from few to many, generally increasing with depth. Texture is clay. Reaction ranges from extremely acid to slightly acid.
The Bkss horizon has hue of 10YR, 2.5Y, or 5Y, and value of 4 to 6. Chroma ranges from 4 to 8 in ped interiors and from 2 to 4 on exterior faces of peds or slickenside faces. Some pedons do not have a dominant matrix color and are multicolored in shades of olive, brown, and gray. Iron depletions in shades of gray and iron accumulations in shades of brown range from few to many and are most common on surfaces of peds or slickensides. Texture is clay or silty clay. Reaction is commonly slightly alkaline or moderately alkaline, but ranges to neutral. Soft masses of calcium carbonate range from common to many and concretions or nodules of carbonate range from few to many. Some pedons have few to common soft masses and/or concretions of manganese.
The 2C horizon, present in some pedons, is highly weathered chalk or calcareous clay. It is massive or has platy rock structure. Reaction is slightly alkaline or moderately alkaline.
Some pedons have a 2Cr horizon below a depth of 60 inches that is weathered chalk bedrock. It can be dug with difficulty with hand tools and is rippable by light machinery.
COMPETING SERIES: These are the
Lacerda,
Redco,
Suggsville, and
Wilcox series in the same family and the
Hannon and
Raylake series in related families. The Hannon series is less acid in the upper 20 inches, is in a fine particle-size family, and has carbonates within 30 inches of the surface. Lacerda soils do not have an argillic horizon and are derived from shale. Raylake soils are in a fine particle-size family and have gypsum crystals in the lower part of the solum. Redco soils do not have an argillic horizon and have hue of 10YR or yellower throughout the subsoil. Suggsville soils are well drained and have a paralithic contact of limestone or chalk within a depth of 40 to 60 inches. Wilcox soils are somewhat poorly drained and have a paralithic contact of acid shale within a depth of 40 to 60 inches.
GEOGRAPHIC SETTING: Oktibbeha soils are on ridges and side slopes on uplands of the Alabama and Mississippi Blackland Prairie (MLRA 135A) and the Southern Coastal Plain (MLRA 133A and 133B) MLRA's. Slopes are generally 1 to 15 percent, but may be as steep as 30 percent in some places. These soils formed in clayey sediments overlying chalk or calcareous clays. The average annual air temperature ranges from 60 to 65 degrees F., and the average annual precipitation ranges from 48 to 56 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Binnsville,
Demopolis,
Faunsdale,
Keiffer,
Kipling,
Maytag,
Sumter,
Vaiden, and
Watsonia series. Binnsville and Demopolis soils are on higher positions and are shallow to bedrock. Faunsdale and Maytag soils are on lower positions and have hue of 10YR or yellower throughout. Keiffer and Sumter soils are on similar positions as Oktibbeha soils and are fine-silty and calcareous to the surface. Kipling soils, on lower positions, are in the fine particle-size family and have dominant hue of 7.5YR or yellower in the upper part of the solum. Vaiden soils, on lower, less convex positions, have dominant hue of 10YR or yellower in the upper part of the solum. Watsonia soils are on similar positions as Oktibbeha soils and are shallow to chalk bedrock.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium to rapid runoff; very slow permeability. No free water has been observed in these soils but soil morphology suggests that they may be saturated within a depth of 1.5 to 3.5 feet of the surface for short periods during winter and spring.
USE AND VEGETATION: Principal use is woodland. Some areas are in pasture, hayland, or cultivated crops. The main crops are cotton, corn, and soybeans. Common trees in wooded areas include loblolly pine, shortleaf pine, southern red oak, post oak, sweetgum, and hickory.
DISTRIBUTION AND EXTENT: Alabama, Arkansas, Georgia, Louisiana,
Mississippi and Tennessee. It is of large extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Auburn, Alabama
SERIES ESTABLISHED: Oktibbeha County, Mississippi in 1907.
REMARKS: These soils were formerly classified as Vertic Hapludalfs. An argillic horizon is not currently recognized in the Vertisol order but is considered an important feature of this soil.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to a depth of about 4 inches (Ap horizon)
Argillic horizon - the zone from about 4 to 13 inches (Bt horizons)
Cambic horizon - the zone from about 13 to 80 inches (Bss and Bkss horizons)
Vertic features - intersecting slickensides beginning at about 13 inches and continuing to a depth of 80 inches. (Bss and Bkss horizons)
SIR- AL0072, AL0113
MLRA 135A, 133A, 133B
National Cooperative Soil Survey
U.S.A.