LOCATION TRUCHOT MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Aquic Calciustolls
TYPICAL PEDON: Truchot clay loam 0 to 2 percent slopes, rangeland (colors are for dry soil unless otherwise noted).
A--0 to 7 inches; very dark brown (10YR 2/2) clay loam, dark grayish brown (10YR 4/2) dry; moderate medium granular structure; hard, friable, slightly sticky and moderately plastic; many fine and medium roots; many fine and medium pores; about 5 percent pebbles; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 10 inches thick)
Bk1--7 to 12 inches; dark grayish brown (10YR 4/2) gravelly clay loam, light grayish brown (10YR 5/2) dry; few fine faint yellowish brown (10YR 5/4) redox concentrations; moderate medium granular structure; hard, friable, slightly sticky and moderately plastic; many fine roots and few medium roots; many fine and medium pores; about 25 percent pebbles; few medium masses of lime; many distinct lime coats on fragments; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (0 to 9 inches thick)
Bk2--12 to 16 inches; brown (10YR 5/3) very gravelly clay loam, pale brown (10YR 6/3) dry, common fine distinct yellowish brown (10YR 5/6) redox concentrations; moderate medium granular structure; very hard, friable, slightly sticky and moderately plastic; few fine and medium roots; common fine and very fine pores; about 50 percent pebbles, 5 percent cobbles; common distinct lime coats on undersides of fragments; common medium masses of lime between fragments; violently effervescent; moderately alkaline (pH 8.4); gradual wavy boundary.
Bk3--16 to 26 inches; brown (10YR 4/3) extremely gravelly clay loam, pale brown (10YR 6/3) dry, few fine faint yellowish brown (10YR 5/6) redox concentrations; massive; very hard, friable, slightly sticky and moderately plastic; few fine and medium roots; few fine and very fine pores; about 60 percent pebbles and 5 percent cobbles; common distinct lime coats on undersides of fragments; few fine masses of lime between fragments; violently effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (Combined thickness of the Bk2 and Bk3 horizons is 9 to 24 inches.)
Bk4--26 to 60 inches; brown (10YR 4/3) extremely gravelly sandy clay loam, pale brown (10YR 6/3) dry; massive; hard, friable, slightly sticky and moderately plastic; few fine roots in upper part; about 60 percent pebbles and 5 percent cobbles; continuous distinct lime coats on fragments; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Teton County, Montana; 2,500 feet west and 2,200 feet south of the NE corner of sec. 14, T. 26 N., R. 8 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 46 degrees F.
Mollic epipedon thickness - 7 to 10 inches.
Depth to seasonal high water table - 24 to 42 inches.
Depth to Bk horizon - 5 to 18 inches.
Soil phases - saline, cool, or gravelly.
Some pedons have an O horizon (organic mat) of 1/2 inch to 4 inches thick but the surface layer when mixed to 7 inches is a clay loam.
A horizon - Value: 3, 4, or 5 dry; 2 or 3 moist
Chroma: 1 or 2
Texture: loam or clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 35 percent--0 to 5 percent cobbles, 0 to 35 percent pebbles
Calcium carbonate equivalent: 5 to 10 percent
EC: 0 to 12 mmhos/cm (saline phase 4 to 12 mmhos/cm)
SAR: 0 to 30; (sodic phase 13 to 30)
Reaction: pH 7.4 to 9.4
Bk1 horizon - Hue: 10YR or 2.5Y
Value: 5 to 8 dry; 3 to 6 moist
Chroma: 1, 2, or 3
Texture: loam or clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 60 percent--0 to 10 percent cobbles, 0 to 50 percent pebbles
Calcium carbonate equivalent: 10 to 35 percent
EC: 0 to 8 mmhos/cm (saline phase 4 to 8 mmhos/cm)
Reaction: pH 7.9 to 9.0
Bk2 horizon - Hue: 10YR or 2.5Y
Value: 6, 7, or 8 dry; 4, 5, 6, or 7 moist
Chroma: 1, 2, or 3
Texture: loam or clay loam
Clay content: 20 to 35 percent
Rock fragments: 25 to 65 percent--0 to 10 percent cobbles, 25 to 55 percent pebbles
Calcium carbonate equivalent: 15 to 35 percent
EC: 0 to 8 mmhos/cm (saline phase 4 to 8 mmhos/cm)
Reaction: pH 7.9 to 9.0
Bk3 horizon - Hue: 10YR or 2.5Y
Value: 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 1, 2, or 3
Texture: loam or clay loam
Clay content: 20 to 35 percent
Rock fragments: 35 to 65 percent--5 to 10 percent cobbles, 30 to 55 percent pebbles
Calcium carbonate equivalent: 15 to 35 percent
EC: 0 to 8 mmhos/cm (saline phase 4 to 8 mmhos/cm)
Reaction: pH 7.9 to 9.0
Bk4 horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: sandy loam, sandy clay loam, loam, or clay loam
Clay content: 15 to 30 percent
Rock fragments: 45 to 80 percent--5 to 10 percent cobbles, 40 to 70 percent pebbles
Calcium carbonate equivalent: 10 to 30 percent
EC: 0 to 8 mmhos/cm (saline phase 4 to 8 mmhos/cm)
Reaction: pH 7.9 to 9.0
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - depressions on dissected alluvial fans and stream terraces.
Elevation - 3,600 to 5,500 feet.
Slope - 0 to 4 percent.
Parent material - calcareous gravelly alluvium derived mostly from limestone, dolomite, and sandstone.
Climate - long, cold winters; cool, moist springs; warm summers.
Mean annual precipitation - 10 to 19 inches.
Mean annual temperature - 39 to 44 degrees F.
Frost-free period - 70 to 115 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Saypo, Tetonview, Judell, Judith, and Windham soils. Saypo soils are fine-loamy. Tetonview soils are poorly drained. Judell, Judith, and Windham soils are well drained.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderately slow permeability. Some pedons have seasonal high water tables at or near the surface due to prolonged flooding during the irrigation season.
USE AND VEGETATION: Truchot soils are used mainly for rangeland and hayland. Potential native vegetation is mainly northern reedgrass, tufted hairgrass, northern mannagrass, Rocky Mountain iris, and shrubby cinquefoil. Kentucky bluegrass and timothy are major increasers under irrigation.
DISTRIBUTION AND EXTENT: Truchot soils are of limited extent. They are in the central and western part of Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Choteau-Conrad Area, parts of Teton and Pondera Counties, Montana, 1991; proposed in Teton County, Montana, 1982.
REMARKS: Soil Interpretation Record: MT0731. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the surface to 7 inches (A horizon); a calcic horizon from 7 to 60 inches (Bk1, Bk2, Bk3, and Bk4 horizons); a particle-size control section from 10 to 40 inches (Bk1, Bk2, Bk3, and Bk4 horizons). Truchot soils have a frigid temperature regime and an ustic moisture regime.