LOCATION BRIDGER MT+WYEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive Ustic Argicryolls
TYPICAL PEDON: Bridger loam, cultivated (colors are for dry soil unless otherwise noted).
A--0 to 9 inches, very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; moderate fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine and very fine roots; many very fine and fine pores; 5 percent gravel, 1 percent stones below surface; neutral (pH 7.0); clear boundary. (7 to 16 inches thick)
Bt--9 to 24 inches; brown (10YR 5/3) clay, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to strong coarse medium and fine blocky structure; very hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine pores; distinct continuous very dark grayish brown (10YR 3/2) moist; clay films on faces of peds; 5 percent gravel, 1 percent stones; neutral (pH 7.0); clear wavy boundary. (10 to 30 inches thick)
Bk1--24 to 36 inches; brown (10YR 5/3) gravelly clay loam, dark brown (10YR 4/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; few fine pores; 15 percent gravel, 5 percent cobbles; few large masses of lime; continuous distinct lime casts on underside of rock fragments; strongly effervescent; moderately alkaline (pH 8.0); gradual boundary. (4 to 15 inches thick)
Bk2--36 to 60 inches, light yellowish brown (2.5Y 6/3) gravelly loam, light olive brown (2.5Y 5/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; few fine pores; 20 percent gravel; 5 percent cobbles; common distinct lime casts on undersides of rock fragments mainly in the upper part of the horizon; disseminated lime; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Gallatin County, Montana; 600 feet east and 300 feet south of the N 1/4 corner of sec. 27, T. 3 N., R. 5 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 36 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 16 inches.
Depth to Bk horizon - 17 to 40 inches.
A Btk and BC horizon is allowed.
A horizon - Hue: 7.5YR, 10YR, or 2.5Y
Value: 3, 4, or 5 dry; 2 or 3 moist
Chroma: 1 or 2
Texture: loam, clay loam
Clay content: 18 to 35 percent
Rock fragments: 5 to 35 percent--0 to 10 percent cobbles and stones, 5 to 25 percent pebbles
Reaction: pH 6.1 to 7.8
Bt horizon - Hue: 7.5YR, 10YR, or 2.5Y
Value: 5 or 6 dry; 3, 4, or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam, silty clay, or clay
Clay content: 35 to 50 percent
Rock fragments: 5 to 35 percent--0 to 10 percent cobbles and stones; 5 to 25 percent pebbles
Reaction: pH 6.1 to 7.8
Bk horizons - Hue: 7.5YR, 10YR, or 2.5Y
Value: 6, 7, or 8 dry; 5, 6, or 7 moist
Chroma: 2, 3, or 4
Texture: clay loam, sandy clay loam, loam
Clay content: 20 to 40 percent
Rock fragments: 5 to 35 percent--0 to 20 percent cobbles and stones; 5 to 30 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 9.0
COMPETING SERIES:
Bangtail (MT) - has a paralithic contact at 20 to 40 inches.
Duckcreek (MT) - has a paralithic contact at 20 to 40 inches.
Echard (UT) - developed in materials with high content of volcanic ash; does not have a horizon of secondary calcium carbonate accumulation.
Melville (MT) - has a loamy-skeletal discontinuity at 17 to 35 inches.
Mollet (MT) - does not have a horizon of secondary carbonate accumulation.
Rattler (MT) - has hue mainly redder than 7.5YR in the argillic horizon; discontinuity of stratified lake sediments.
Sevier (UT) - bedrock at depths of 20 to 40 inches.
GEOGRAPHIC SETTING:
Landform - alluvial fans, stream terraces, drainageways, moraines, hills, mountains.
Elevation - 4,500 to 8,000 feet.
Slope- 0 to 45 percent.
Parent material - alluvium, colluvium, or till from a variety of igneous, metamorphic, and sedimentary rock.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 30 inches.
Mean annual air temperature - 34 to 45 degrees F.
Frost-free period - 50 to 70 days.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Bridger soils are used mainly for native range and for dryland and irrigated production of hay. Potential native vegetation is mainly bluebunch wheatgrass, Idaho fescue, rough fescue, prairie junegrass, bluegrass, lupine, and silver sage.
DISTRIBUTION AND EXTENT: Bridger soils are extensive in valleys of northern Rocky Mountain region in Montana.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Gallatin Valley Area, Montana, 1905.
REMARKS: Soil interpretations records: MT0056, MT7055, MT1067, MT0368, MT0902. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 9 inches (A horizon); an argillic horizon from 9 to 24 inches that is also the particle-size control section (Bt horizon); horizons of carbonate accumulation from 24 to 60 inches (Bk1, Bk2 horizons). Bridger soils have a cryic temperature regime and an ustic moisture regime.