LOCATION BLACKMORE MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Blackmore silt loam, in hayland (Colors are for dry soil unless otherwise noted).
Ap--0 to 6 inches; very dark gray (10YR 3/1) silt loam, black (10YR 2/1) moist; moderate fine granular structure; slightly hard, friable, moderately sticky and slightly plastic; common medium and fine roots, many very fine roots; slightly acid (pH 6.4); abrupt smooth boundary. (4 to 8 inches thick)
AB--6 to 10 inches; very dark gray (10YR 3/1) silt loam, black (10YR 2/1) moist; moderate fine and medium angular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common medium and fine roots, many very fine roots; neutral (pH 6.6); abrupt wavy boundary. (0 to 7 inches thick)
Bt1--10 to 15 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 4/3) moist, with some very dark gray (10YR 3/1) moist interfingering of mollic material; strong fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few medium and fine roots, many very fine roots; common distinct clay films on faces of peds and lining pores; neutral (pH 6.8); gradual smooth boundary.
Bt2--15 to 27 inches; yellowish brown (10YR 5/4) silty clay loam, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and slightly plastic; few medium and fine roots, common very fine roots; common distinct clay films on faces of peds and lining pores; neutral (pH 7.0); clear smooth boundary. (Combined thicknes of Bt horizons is 12 to 32 inches).
Bk1--27 to 42 inches; pale brown (10YR 6/3) silt loam, yellowish brown (10YR 5/4) moist; weak medium subangular blocky structure; slightly hard, firm, moderately sticky and slightly plastic; few fine roots; many fine threads and seams of lime; violently effervescent; moderately alkaline (pH 8.4); gradual smooth boundary. (10 to 20 inches thick)
Bk2-- 42 to 60 inches; yellowish brown (10YR 5/4) silt loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; common medium masses of lime; strongly effervescent; moderately alkaline (pH 7.9).
TYPE LOCATION: Gallatin County, Montana; 1100 feet south and 1800 feet west of the northeast corner of sec. 27, T.2S., R.6E.
RANGE IN CHARACTERISTICS:
Soil temperature - 39 to 43 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 8 to 15 inches and may include part of the Bt horizon.
Depth to the Bk horizon - 20 to 40 inches.
Ap, AB horizons - Value: 3 or 4 dry; 2 or 3 moist
Clay content: 22 to 27 percent
Reaction: pH 6.1 to 7.3
Bt horizons - Value: 4 or 5 dry; 3 or 4 moist
Chroma: 3 or 4
Clay content: 27 to 35 percent
Reaction: pH 6.1 to 7.3
Bk1 horizon - Value: 5, 6 or 7 dry; 4, 5 or 6 moist
Chroma: 3, 4 or 6
Texture: silt loam, silty clay loam
Clay content: 15 to 30 percent
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 7.4 to 8.4
Bk2 horizon - Value: 5, 6 or 7 dry; 4, 5 or 6 moist
Chroma: 3, 4 or 6
Texture: silt loam, silty clay loam
Clay content: 15 to 30 percent
Rock fragments: 0 to 10 percent pebbles
Calcium carbonate equivalent: 10 to 30 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Blackdog (MT) - has chroma of 2 or more in the A horizons.
Farland (MT) - does not have a calcic horizon.
Granath (CO) - 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 - 4,800 to 5,500 feet.
Slope - 0 to 15 percent.
Parent material - loess
Climate - long cold winters; moist springs; warm summers.
Mean annual precipitation - 18 to 22 inches.
Mean annual air temperature - 37 to 41 degrees F.
Frost-free period - 80 to 95 days.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Blackmore soils are used mainly for cropland and pasture. Potential native vegetation includes subalpine needlegrasses, Idaho fescue, mountain brome, lupine, sticky geranium, wild rose and snowberry as well as other forbs, grasses and woody shrubs.
DISTRIBUTION AND EXTENT: Blackmore 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: MT1643. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the surface to 10 inches (Ap, AB horizons); an argillic horizon which is the particle-size control section from 10 to 27 inches (Bt1, Bt2 horizons); a calcic horizon from 27 to 60 inches (Bk1, Bk2 horizons). The Blackmore soil has a frigid temperature regime and an ustic moisture regime.