LOCATION MARTAB MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive Ustollic Haplocryalfs
TYPICAL PEDON: Martab loam, forested (Colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches; moderately decomposed leaves, needles, and twigs. (1 to 2 inches thick)
A--2 to 6 inches; very dark grayish brown (10YR 3/2) loam, black (10YR 2/1) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine, and few medium and coarse roots; 5 percent pebbles; slightly acid (pH 6.4); clear smooth boundary. (4 to 8 inches thick)
E--6 to 17 inches; reddish gray (5YR 5/2) clay loam, reddish brown (5YR 4/3) moist; moderate fine granular structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine and few medium and coarse roots; 5 percent pebbles; slightly acid (pH 6.2); clear smooth boundary. (7 to 11 inches thick)
Bt1--17 to 35 inches; reddish brown (5YR 4/3) clay, dark reddish brown (5YR 3/4) moist; strong medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; common distinct clay films on faces of peds and lining pores; 5 percent pebbles; slightly acid (pH 6.2); clear smooth boundary. (10 to 20 inches thick)
Bt2--35 to 50 inches; reddish brown (5YR 4/3) clay, dark reddish brown (5YR 3/4) moist; strong medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; common distinct clay films on faces of peds and lining pores; 15 percent soft siltstone chips; slightly effervescent; neutral (pH 7.2); clear smooth boundary. (10 to 15 inches thick)
Bk--50 to 60 inches; reddish gray (5YR 5/2) clay loam, brown (7.5YR 4/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; 15 percent soft siltstone chips; common fine masses and seams of lime; strongly effervescent; slightly alkaline (pH 7.8).
TYPE LOCATION: Gallatin County, Montana; 1000 feet west and 2600 feet south of the northeast corner of section 27, T.5N., R.4E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 36 to 40 degrees F.
Mean summer soil temperature - 45 to 47 degrees F.
Moisture control section - between 4 and 12 inches; not dry in all parts for 45 consecutive days.
Depth to Bk horizon - 35 to 60 inches.
Soil phases: stony.
A horizon - Value: 3, 4 or 5 dry; 2 or 3 moist
Chroma: 1, 2 or 3
Clay content: 18 to 27 percent
Rock fragments: 0 to 20 percent--0 to 10 percent pebbles, 0 to 5 percent cobbles, 0 to 3 percent stones
Reaction: pH 6.1 to 7.8
E horizon - Hue: 5YR, 7.5YR or 10YR
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2, 3, or 4
Clay content: 27 to 35 percent
Rock fragments: 0 to 15 percent--0 to 10 percent pebbles,
0 to 5 percent cobbles
Reaction: pH 6.1 to 7.8
Bt1 horizon - Hue: 2.5YR, 5YR or 7.5YR
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 3 or 4
Texture: clay loam or clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 25 percent--0 to 20 percent pebbles,
0 to 5 percent cobbles
Reaction: pH 6.1 to 7.8
Bt2 horizon - Hue: 2.5YR, 5YR or 7.5YR
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 3 or 4
Texture: clay loam or clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 25 percent--0 to 20 percent pebbles, 0 to 5 percent cobbles
Reaction: pH 6.1 to 7.8
Bk horizon - Hue: 2.5YR, 5YR or 7.5YR
Chroma: 2, 3, 4, or 6
Clay content: 27 to 35 percent
Rock fragments: 0 to 30 percent; 0 to 20 percent pebbles, 0 to 10 percent cobbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
There are no competing series.
GEOGRAPHIC SETTING:
Landform - mountains and esarpments.
Elevation - 5,300 to 6,500 feet.
Slope - 15 to 60 percent.
Parent material - sandstone colluvium.
Climate - long, cold winters; cool, moist springs; short summers.
Mean annual precipitation - 20 to 24 inches.
Mean annual air temperature - 34 to 38 degrees F.
Frost-free period - 50 to 70 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Martab soils are used mainly for timber production, recreation, rangeland, and wildlife habitat. Potential native vegetation may include Douglas fir, snowberry, pinegrass, white spiraea, and Rocky Mountain maple.
DISTRIBUTION AND EXTENT: Martab 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 records: MT1422, MT1605. Diagnostic horizons and features recognized in this pedon are: a dark colored horizon from 2 to 6 inches (A horizon); an argillic horizon from 17 to 50 inches (Bt1, Bt2 horizons); a horizon of secondary carbonate accumulation from 50 to 60 inches (Bk horizon); a particle-size control section from 17 to 37 inches (Bt1, Bt2 horizons). Martab soils have an ustic moisture regime and a cryic temperature regime.