LOCATION BLACKDOG MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Blackdog silt loam in cropland (Colors are for dry unless otherwise noted).
Ap--0 to 6 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; neutral (pH 7.0); clear smooth boundary. (4 to 8 inches thick)
A2--6 to 10 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and plastic; few very fine roots; neutral (pH 7.3). (0 to 6 inches thick)
Bt1--10 to 14 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, moderately sticky and moderately plastic; few very fine roots; common distinct clay films on faces of peds and lining pores; slightly alkaline (pH 7.6); clear smooth boundary.
Bt2--14 to 19 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 4/3) moist; weak medium prismatic structure parting to moderate fine subangular blocky; hard, friable, moderately sticky and moderately plastic; few very fine roots; common faint clay films on faces of peds and lining pores; slightly alkaline (pH 7.6); abrupt smooth boundary. (Combined thicknes of Bt horizons is 8 to 22 inches).
Bk1--19 to 26 inches; pale brown (10YR 6/3) silt loam, dark yellowish brown (10YR 4/4) moist; weak medium and fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common fine threads and seams of lime; violently effervescent; moderately alkaline (pH 8.2); gradual smooth boundary. (6 to 15 inches thick)
Bk2--26 to 60 inches; light gray (10YR 7/2) silt loam, brown (10YR 5/3) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; disseminated lime; few fine masses of lime; violently effervescent, moderately alkaline (pH 8.2).
TYPE LOCATION: Gallatin County, Montana; 850 feet south and 1500 feet east of the northwest corner of sec. 26, T.1N., R.5E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 41 to 45 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 15 inches and may include part of the Bt horizon.
Depth to the Bk horizon - 18 to 30 inches.
A horizons - Value: 3, 4 or 5 dry; 2, 3 or 4 moist
Chroma: 2 or 3
Clay content: 20 to 27 percent
Reaction: pH 6.6 to 7.3
Bt1 horizon - Value: 4 or 5 dry; 3 or 4 moist
Chroma: 3 or 4
Clay content: 27 to 35 percent
Reaction: pH 6.6 to 7.8
Bt2 horizon - Value: 4, 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4
Clay content: 27 to 35 percent
Reaction: pH 6.6 to 7.8
Note: Some pedons contain a Bt3 horizon with silt loam textures.
Bk horizons - Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2, 3 or 4
Clay content: 15 to 25 percent
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Dingle (ID) - are calcareous throughout; are somewhat poorly drained.
Farland (ND) - does not have a calcic horizon.
Granath (CO) - does not have a calcic horizon; has Bt horizon with hue of 7.YR or redder; depth to horizons of secondary carbonate accumulation range from 40 to more than 70 inches.
Hanaker (MT) - does not have a calcic horizon.
Morton (ND) - has a paralithic contact at 20 to 40 inches.
Xavier (MT) - does not have a calcic horizon.
GEOGRAPHIC SETTING:
Landform - relict stream terraces.
Elevation - 4,700 to 5,700 feet.
Slope- 0 to 15 percent.
Parent material - loess
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual air temperature - 39 to 43 degrees F.
Frost-free period - 90 to 110 days.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Blackdog soils are used mainly for cropland, hayland and pasture. Potential native vegetation may include bluebunch wheatgrass, Idaho fescue, Richardson needlegrass, mountain brome, sedges, lupine, western yarrow, sticky geranium, common snowberry and wild rose as well as other grasses, forbs and other woody shrubs.
DISTRIBUTION AND EXTENT: Blackdog soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Gallatin County, Montana, 1997.
REMARKS: Soil interpretation record: MT1644. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the surface to 14 inches (Ap, A2, Bt1 horizons); an argillic horizon from 10 to 19 inches which is also the particle-size control section (Bt1, Bt2 horizon); a calcic horizon from 19 to 60 inches (Bk1, Bk2 horizons). Blackdog soils have a frigid temperature regime and an ustic moisture regime.