LOCATION KOBEL AR+MO

Established Series
Rev. LBW
10/2018

KOBEL SERIES

The Kobel series consists of very deep, poorly drained and very poorly drained, very slowly permeable soils that formed in clayey alluvium. These level to nearly level soils are on floodplains in the Western Lowlands of the lower Mississippi valley; MLRA 131. Slope gradient ranges from 0 to 3 percent. The mean annual temperature near the type location is about 62 degrees and the mean annual precipitation is about 50 inches.

TAXONOMIC CLASS: Fine, smectitic, nonacid, thermic Vertic Endoaquepts

TYPICAL PEDON: Kobel silty clay--cultivated. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 5 inches; very dark gray (10YR 3/1) silty clay; weak fine subangular blocky structure; firm, many fine roots; slightly acid; abrupt smooth boundary. (4 to 9 inches thick)

Bg1--5 to 17 inches; dark gray (10YR 4/1) clay; strong medium blocky structure; very firm, plastic; few fine roots; common medium distinct yellowish brown (10YR 5/6) iron accumulations; neutral; clear smooth boundary.

Bg2--17 to 45 inches; gray (10YR 5/1) clay; moderate medium blocky structure; very firm, plastic; few slickensides; few fine roots; common medium distinct yellowish brown (10YR 5/6) iron accumulations and common medium faint dark gray (10YR 4/1) iron depletions; few fine iron-manganese concretions; neutral; gradual smooth boundary.

Bg3--45 to 55 inches; gray (10YR 5/1) clay; moderate medium subangular blocky structure; very firm, plastic; few slickensides; few fine roots; common medium distinct yellowish brown (10YR 5/6) iron accumulations; few fine iron-manganese concretions; few fine distinct black (10YR 2/1) manganese accumulations on faces of peds; slightly alkaline; gradual smooth boundary. (Combined thickness of the Bg horizon ranges from 21 to 56 inches.)

Cg1--55 to 63 inches; gray (10YR 5/1) sandy clay; massive; firm; few fine roots; common medium distinct strong brown (7.5YR 5/6) iron accumulations; few fine iron-manganese concretions; few fine distinct black (10YR 2/1) manganese accumulations in matrix; moderately alkaline; clear smooth boundary. (6 to 10 inches thick)

C2g--63 to 72 inches; gray (10YR 5/1) silty clay; massive; firm; very plastic; few fine roots; common medium faint dark gray (10YR 4/1) iron depletions; few fine distinct black (10YR 2/1) manganese accumulations in matrix; moderately alkaline.

TYPE LOCATION: Clay County, Arkansas; 1 1/2 miles south and 1 mile east of Hargraves Corner; SW1/4/SE1/4NE1/4 sec. 33, T. 19 N., R. 8 E.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 30 to 60 inches. Cracks 1 to 3 cm wide develop to a depth of 20 inches or deeper in most years. Reaction ranges from strongly acid to neutral in the A horizon; slightly acid to moderately alkaline in the B horizon and neutral to moderately alkaline in the C horizon.

The A horizon has hue of 10YR, value of 3 or 4, and chroma of 1 or 2; or with value of 5, and chroma of 1. Iron accumulations are in shades of gray, yellow or brown. A horizons with value of 3 are less than 10 inches thick. Texture is silty clay loam, silty clay or clay. Thin silt loam overwash phases are also recognized.

The Bg horizon has hue of 10YR 2.5Y or 5Y, value of 4 to 6, and chroma of 1; or is neutral with value of 4 to 6. Iron accumulations and depletions are in shades of gray, brown, yellow, or red. Texture is silty clay loam, silty clay or clay. The average clay content of the 10 to 40 inch control section ranges from 35 to 55 percent.

The C horizon has hue of 10YR 2.5Y or 5Y, value of 4 to 6, and chroma of 1; or is neutral with value of 4 to 6. Iron accumulations and depletions are in shades of gray, brown, yellow, or red. Texture commonly is silty clay or sandy clay but it ranges from fine sandy loam through clay.

COMPETING SERIES: Kobel is the only series in the family.

GEOGRAPHIC SETTING: Kobel soils are on depressional to nearly level floodplains, abandoned channels and oxbows of the White, Black, Cache and St. Francis Rivers and other larger streams in the Western Lowlands and St. Francis Basin of the Southern Mississippi Valley. Slopes range from 0 to 3 percent. These soils formed in clayey alluvium with montmorillonitic mineralogy. They are flooded for brief to very long periods nearly every year unless protected by levees. The mean annual air temperature ranges from about 58 to 64 degrees F. and the mean annual precipitation ranges from about 46 to 52 inches.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Amagon, Askew, Commerce, Dubbs, Foley, Taylorbay, Tipp, Tuckerman, Wardell and Yancopin series. Amagon soils are on adjacent terraces and in a fine-silty particle size class. Askew soils are on adjacent terraces; are in a fine-silty particle size class and are moderately well drained. Commerce and Yancopin soils are on similar landscape positions; are in a fine-silty particle size class, do not have cambic horizons and are somewhat poorly drained. Dubbs soils are on adjacent higher terraces; are in a fine-silty particle size class and are well drained. Foley soils are on adjacent terraces; are in a fine-silty particle size class and have a natric horizon. Taylorbay soils are on similar landscapes; have a mollic epipedon; are in a fine-silty particle size class and are well drained. Tipp soils are on similar landscape positions; have a mollic epipedon and are moderately well drained. Tuckerman and Wardell soils are on similar positions and in a fine-loamy particle size class.

DRAINAGE AND PERMEABILITY: Poorly drained on broad, level to undulating floodplains and very poorly drained in abandoned channels and oxbows; slow or very slow runoff; very slow permeability. Typically, these soils flood annually during the winter and spring, unless protected by levees. An apparent water table is within 1 foot of the soil surface from December to May, most years.

USE AND VEGETATION: Most of this soil is cleared and cultivated. Major crops include rice, grain sorghum, soybeans, and cotton. Minor unprotected areas are still wooded. The native vegetation is mixed bottomland hardwoods.

DISTRIBUTION AND EXTENT: MLRA 131. Northeast Arkansas, southeast Missouri, and possibly Kentucky, Tennessee, and Louisiana. The series is of moderate extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: AUBURN, ALABAMA

SERIES ESTABLISHED: Clay County, Arkansas; 1975.

REMARKS: Diagnostic horizons and features recognized in this soil are:

Ochric Epipedon-surface to a depth of 5 inches.

Cambic horizon-zone from 5 to 55 inches.

Kobel soils were formerly included in the Sharkey series and formerly classified as Grumusols intergrading to Alluvial soils.

National Cooperative Soil Survey
U.S.A.