LOCATION LOWLAND MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Vitrandic Haplocryolls
TYPICAL PEDON: Lowland ashy loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 12 inches; dark gray (10YR 4/1) ashy loam, black (10YR 2/1) moist; moderate fine and medium granular structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine interstitial pores; neutral (pH 6.8); clear smooth boundary. (8 to 16 inches thick)
Bw--12 to 20 inches; grayish brown (10YR 5/2) cobbly ashy sandy loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common fine pores; 20 percent pebbles and 10 percent cobbles; neutral (pH 7.2); clear smooth boundary. (6 to 16 inches thick)
BC--20 to 38 inches; light gray (10YR 6/1) very cobbly ashy sandy loam, dark grayish brown (10YR 4/2) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common fine interstitial pores; 25 percent pebbles, 15 percent cobbles and 10 percent stones; slightly alkaline (pH 7.4); gradual wavy boundary. (13 to 20 inches thick)
C--38 to 60 inches; light gray (10YR 7/1) very cobbly ashy loamy sand, grayish brown (10YR 5/2) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine roots; 20 percent pebbles, 20 percent cobbles, 15 percent stones; slightly alkaline (pH 7.4).
TYPE LOCATION: Jefferson County, Montana; 1,600 feet west and 1,200 feet north of the SE corner of sec. 17, T. 6 N., R. 6 W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 38 to 42 degrees F.
Mean summer soil temperature - 55 to 59 degrees F.
Moisture control section - between 8 and 24 inches.
Mollic epipedon thickness - 8 to 16 inches.
Volcanic glass - 25 to 30 percent.
Al + 1/2 Fe - .11 to .20
Surface stones or boulders - 0 to 0.1 percent.
A horizon - Hue: 10YR or 2.5Y
Value: 3, 4, or 5 dry; 2 or 3 moist
Chroma: 1 or 2
Texture: ashy loam, ashy sandy clay loam or ashy sandy loam
Clay content: 15 to 23 percent
Rock fragments: 0 to 25 percent--0 to 5 percent cobbles and stones, 0 to 25 percent pebbles
Reaction: pH 6.1 to 7.3
Bw horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry, 3, 4 or 5 moist
Chroma: 1, 2 or 3
Texture: ashy loam, ashy sandy clay loam, ashy sandy loam, or ashy coarse sandy loam
Clay content: 12 to 23 percent
Rock fragments: 25 to 50 percent--5 to 20 percent cobbles and stones, 20 to 30 percent pebbles
Reaction: pH 6.1 to 7.3
BC horizon - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 1 or 2
Texture: ashy loam, ashy sandy loam, or ashy coarse sandy loam
Clay content: 12 to 20 percent
Rock fragments: 35 to 60 percent--10 to 25 percent cobbles and stones; 25 to 35 percent pebbles
Reaction: pH 6.1 to 7.8
C horizon - Hue: 10YR or 2.5Y
Value: 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 1 or 2
Texture: ashy coarse sandy loam, ashy sandy loam, ashy loam, or ashy loamy sand
Clay content: 5 to 18 percent
Rock fragments: 35 to 60 percent--10 to 40 percent cobbles and stones; 15 to 50 percent pebbles
Reaction: pH 6.1 to 7.8
COMPETING SERIES:
Brickel (WA) - has granite bedrock at 20 to 40 inches.
Edgway (ID) - has a udic moisture regime.
Lagall (ID) - has a udic moisture regime.
GEOGRAPHIC SETTING:
Landform - alluvial fans, hills and mountains.
Elevation - 5,500 to 7,500 feet.
Slope - 4 to 60 percent.
Parent material - colluvium or slope alluvium from tuffaceous volcanic rocks or rhyolite.
Climate - long, cold winters; cool, moist springs; cool, short summers.
Mean annual precipitation - 15 to 24 inches.
Mean annual air temperature - 36 to 40 degrees F.
Frost-free period - 30 to 70 days.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Lowland soils are mainly used for rangeland, watershed, and as wildlife habitat. The potential native vegetation is mainly rough fescue, bluebunch wheatgrass, Columbia needlegrass, Idaho fescue, and big sagebrush. Some areas have an overstory of Douglas-fir and lodgepole pine.
DISTRIBUTION AND EXTENT: Lowland soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretation record: MT1729, MT3018, MT3019. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 12 inches (A horizon); a cambic horizon from 12 to 20 inches (Bw horizon); a particle-size control from 10 to 40 inches (Bw, BC, and C horizons). Lowland soils have a cryic temperature regime and an ustic moisture regime.