LOCATION HILGER MT+SDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Hilger very stony loam, rangeland (colors are for dry soil unless otherwise noted).
A--0 to 5 inches; very dark grayish brown (10YR 3/2) very stony loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; slightly hard, very friable, nonsticky and nonplastic; many fine and very fine roots; 10 percent stones, 15 percent cobbles, 15 percent pebbles; slightly alkaline (pH 7.8); clear wavy boundary. (4 to 8 inches thick)
Bt1--5 to 9 inches; brown (10YR 4/3) very cobbly clay loam, dark brown (10YR 3/3) moist; moderate medium prismatic structure parting to strong fine subangular blocky; hard, firm, moderately sticky and moderately plastic; many very fine roots and pores; 5 percent stones, 25 percent cobbles, 15 percent pebbles; many faint clay film on faces of peds and on surface of rock fragments; slightly alkaline (pH 7.8); clear wavy boundary.
Bt2--9 to 15 inches; brown (10YR 5/3) extremely cobbly clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to strong very fine subangular blocky; hard, firm, moderately sticky and moderately plastic; many very fine roots and pores; continuous faint clay films on faces of peds and on surface of coarse fragments; 5 percent stones, 35 percent cobbles, 25 percent pebbles; slightly alkaline (pH 7.8); clear wavy boundary. (Combined thickness of the Bt horizons is 6 to 18 inches.)
Bk1--15 to 19 inches; light brownish gray (2.5Y 6/2) extremely cobbly loam, grayish brown (2.5Y 5/2) moist; moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine roots and pores; 5 percent stones, 30 percent cobbles, 25 percent pebbles; few large masses of lime; continuous distinct lime casts on underside of rock fragments; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary.
Bk2--19 to 24 inches; light gray (2.5Y 7/2) extremely cobbly loam, grayish brown (2.5Y 5/2) moist; moderate very fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; 5 percent stones, 45 percent cobbles, 10 percent pebbles; common fine masses and filaments of lime; continuous distinct lime casts on surface of rock fragments; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (6 to 10 inches thick)
BC--24 to 60 inches; light yellowish brown (2.5Y 6/4) extremely stony loam, olive brown (2.5Y 4/4) moist; massive; hard, very friable, nonsticky and nonplastic; 20 percent stones, 30 percent cobbles, 20 percent pebbles; disseminated lime; strongly effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Cascade County, Montana; about 260 feet north and 1,050 feet east of the SW corner of sec. 5, T. 18 N., R. 2 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 38 to 47 degrees.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 14 inches.
Control section - 25 to 35 percent clay.
Rock fragments - 35 to 80 percent in the control section.
Depth to calcic horizon - 13 to 24 inches.
Rock fragments, surface cover: 0 to 20 percent stones and boulders.
A horizon - Hue: 7.5YR or 10YR
Value: 3 or 4 dry; 2 or 3 moist
Texture: loam, clay loam, sandy loam, or sand clay loam
Clay content: 10 to 35 percent
Rock fragments: 15 to 60 percent--10 to 35 percent cobbles, stones, and boulders; 5 to 25 percent pebbles
Reaction: pH 6.6 to 7.8
Bt horizons - Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2, 3, or 4
Texture: loam, clay loam, or sandy clay loam
Clay content: 25 to 35 percent
Rock fragments: 35 to 80 percent--35 to 60 percent cobbles, stones, and boulders; 10 to 30 percent pebbles
Reaction: pH 7.4 to 8.4
Bk horizons - Hue: 2.5Y, 10YR, or 7.5YR
Value: 5, 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 2, 3 or 4
Texture: loam, sandy loam, or clay loam
Clay content: 15 to 35 percent
Rock fragments: 35 to 85 percent--25 to 70 percent cobbles, stones, and boulders; 15 to 35 percent pebbles
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 7.9 to 9.0
BC horizon - Hue: 10YR, 7.5YR, or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: loam, sandy loam, or clay loam
Clay content: 15 to 30 percent
Rock fragments: 35 to 80 percent--25 to 70 percent cobbles, stones, and boulders; 15 to 35 percent pebbles
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Bendire (CO) - has lithic contact at moderate depths.
Blaincreek (MT) - has lithic contact at moderate depths.
Borpark (CO) - has calcareous Bt horizons.
Crackerville (T)(MT) - moderately slow permeability; medium acid surface reaction; contaminated by zinc, lead, arsenic, and sulfur.
Crampton (MT) - has a paralithic contact at 20 to 40 inches and a lithic contact at 40 to 60 inches.
Curecanti (CO) - does not have a consistent k horizon above a depth of 40 inches.
Harol (UT) - extremely cobbly loamy sand or extremely cobbly sand C horizons.
Harpole (UT) - does not have a horizon of secondary carbonate accumulation.
Holter (MT) - does not have a calcic horiozn.
Quinncreek (MT) - has a lithic contact of shale at depths of 20 to 40 inches.
Sawbuck (MT) - does not have a horizon of secondary carbonate accumulation.
Sawicki (MT) - does not have horizons of secondary carbonate accumulation.
Shawmut (MT) - less than 35 percent stones and cobbles in the particle-size control section; has Btk horizons.
Shirttail (SD) - does not have a horizon of secondary carbonate accumulation.
Wickes (MT) - has a lithic contact of igneous rock at depths of 20 to 40 inches.
Widtsoe (UT) - strongly cemented calcic horizon; has hue redder than 7.5YR.
GEOGRAPHIC SETTING:
Landform - alluvial fans; mountains; stream terraces; moraines.
Elevation - 3,000 to 6,200 feet.
Slope- 0 to 60 percent.
Parent material - alluvium, colluvium, or till. Mainly fine grained igneous rock and hard sandstone.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 25 inches.
Mean annual air temperature - 36 to 45 degrees F.
Frost-free period - 70 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Hilger soils are used mainly for rangeland, some areas are in cropland. Potential native vegetation is bluebunch wheatgrass, Idaho fescue, rough fescue, green needlegrass, western wheatgrass, bluegrasses, forbs, and in places low density stands of ponderosa pine.
DISTRIBUTION AND EXTENT: Hilger soils are of moderate extent in central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Reconnaissance Soil Survey of central Montana, 1946.
REMARKS: Soil interpretations records: MT0102, MT0898, MT0164, and MT0163. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 9 inches (A, Bt1 horizons); an argillic horizon from 5 to 15 inches (Bt1, Bt2 horizons); a calcic horizon from 15 to 24 inches (Bk1, Bk2 horizons); a particle size control section from 5 to 15 inches (Bt1, Bt2 horizons). Hilger soils have a frigid temperature regime and an ustic moisture regime.