LOCATION THIBADEAU MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, frigid Oxyaquic Ustifluvents
TYPICAL PEDON: Thibadeau clay loam, in rangeland (colors for dry soil unless otherwise noted).
A--0 to 2 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak very fine granular structure; soft, very friable, sticky and plastic; many very fine roots; common very fine pores; strongly alkaline (pH 8.8); clear smooth boundary. (1 to 7 inches thick)
C--2 to 14 inches; grayish brown (2.5Y 5/2) clay loam consisting of thin layers of loam and fine sandy loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, friable, sticky and plastic; many very fine roots; common very fine pores; strongly effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (6 to 15 inches thick)
Cyz--14 to 60 inches; light olive brown (2.5Y 5/4) clay loam consisting of thin layers of loam and fine sandy loam, olive brown (2.5Y 4/4) moist; many fine distinct yellowish brown (10YR 5/6) dry redox concentrations below 20 inches and few faint above 20 inches; massive; hard, friable, sticky and plastic; few very fine roots; common very fine pores; common fine masses and seams of gypsum and other salts; strongly effervescent; very strongly alkaline (pH 9.6).
TYPE LOCATION: Hill County, Montana; 1,600 feet north and 600 feet east of the SW corner of sec. 11, T. 35 N., R. 12 E.
RANGE OF CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Soil moisture control section - between 4 and 12 inches.
Depth to water table - 24 to 42 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 3, 4, or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam, loam, silty clay loam, clay, or silty clay
Clay percent: 15 to 55 percent
Electrical conductivity: 8 to 16 mmhos/cm
Sodium adsorption ratio: 8 to 20
Reaction: pH 7.4 to 9.6
C horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam, loam or silty clay loam with or without thin strata of loam, clay loam, silty clay loam, fine sandy loam, or silt loam
Clay content: 18 to 35 percent
Electrical conductivity: 8 to 16 mmhos/cm
Sodium adsorption ratio: 13 to 20
Reaction: pH 7.4 to 9.6
Cyz horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4
Texture: clay loam, loam or silty clay loam with or without thin strata of fine sandy loam, loam, clay loam, silty clay loam, or silt loam
Clay content: 18 to 35 percent
Electrical conductivity: 8 to 16 mmhos/cm
Sodium adsorption ratio: 13 to 30
Gypsum: 2 to 5 percent
Reaction: pH 7.4 to 9.6
Gypsum and other salts are inherent in the parent material.
COMPETING SERIES:
Fairsmith (MT) - has a discontinuity of sandy or sandy-skeletal material at depths of 40 to 60 inches; does not have an SAR of 8 or greater; does not have EC of 8 mmhos/cm or greater.
Pieriver (MT) - does not have an SAR of 8 or greater; does not have an EC of 8 mmhos/cm or greater.
GEOGRAPHIC SETTING:
Landform - flood plains.
Elevations - 2,300 to 3,500 feet.
Slopes are 0 to 4 percent.
Parent material - alluvium.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches, most of which falls during spring and early summer.
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 105 to 135 days.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderately slow permeability.
USE AND VEGETATION: Thibadeau soils are used as rangeland, woodland, irrigated and nonirrigated cropland. The potential plant community for rangeland is western wheatgrass, inland saltgrass, alkali sacaton, greasewood, gardner saltbush, and shadscale saltbush. The potential plant community for woodland is plains cottonwood, western wheatgrass, alkaligrass, common snowberry, prairie junegrass, rose, American licorice, Saskatoon serviceberry, and poison ivy.
DISTRIBUTION AND EXTENT: Thibadeau soils are moderately extensive throughout Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Hill County, Montana, 1994; proposed in Hill County, Montana 1992. Thibadeau is the name of a lake in Hill County, Montana.
REMARKS: Soil interpretation record: MT1348, MT1349. The diagnostic horizon and features recognized in this pedon are: a ochric epipedon from 0 to 7 inches (A and part of C2 horizons); a particle-size control section from 10 to 40 inches (part of C2 and Cyz horizons). Thibadeau soils have a frigid temperature regime and an ustic moisture regime that borders on aquic.
ADDITIONAL DATA: Laboratory data--S91MT-041-7.