LOCATION BURRFOOT MTEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy, frigid Vitrandic Haplustolls
TYPICAL PEDON: Burrfoot gravelly ashy sandy clay loam, in rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 5 inches; dark grayish brown (10YR 4/2) gravelly ashy sandy clay loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots and common fine and medium roots; 5 percent angular cobbles and 15 percent pebbles; neutral (pH 6.8); clear wavy boundary.
A2--5 to 12 inches; brown (10YR 4/3) very gravelly ashy sandy clay loam, dark brown (10YR 3/3) moist; weak fine granular structure; slightly hard, friable, slightly sticky and plastic; many very fine roots and common fine and medium roots; common very fine and few fine pores; 15 percent angular cobbles and 30 percent pebbles; neutral (pH 7.0); clear wavy boundary. (Combined thickness of A horizons is 8 to 15 inches.)
Bw1--12 to 20 inches; light olive brown (2.5Y 5/4) very gravelly ashy coarse sandy loam, olive brown (2.5Y 4/4) moist; weak coarse subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; many very fine roots and few fine and medium roots; common very fine pores; 15 percent angular cobbles and 35 percent pebbles; neutral (pH 7.0); gradual wavy boundary.
Bw2--20 to 29 inches; light yellowish brown (2.5Y 6/4) very gravelly ashy coarse sandy loam, dark yellowish brown (10YR 4/6) moist; weak coarse subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; common very fine and few fine roots; common very fine pores; 15 percent angular cobbles and 35 percent pebbles; neutral (pH 7.2); gradual wavy boundary. (Combined thickness of Bw horizons is 15 to 30 inches.)
BC--29 to 48 inches; light gray (2.5Y 7/1) ashy sandy loam, light yellowish brown (2.5Y 6/3) moist; massive; slightly hard, very friable, slightly sticky and nonplastic; few very fine roots; common very fine pores; slightly effervescent in lower portion; 10 percent pebbles; slightly alkaline (pH 7.8); gradual wavy boundary. (10 to 25 inches thick)
Cr--48 to 60 inches; light gray (10YR 7/2) semi-consolidated welded tuff that crushes to very gravelly coarse sandy loam; neutral (pH 6.6).
TYPE LOCATION: Deer Lodge County, Montana; 400 feet east and 1300 feet north of the SW corner of sec. 18, T. 5 N., R. 10 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 46 degrees F.
Moisture control section - between 8 and 24 inches.
Volcanic glass - 30 to 50 percent in the coarse silt and sand fraction of one or more horizons within 30 inches.
Acid oxalate Al + 1/2 Fe - .12 to .20 percent
Mollic epipedon thickness - 8 to 15 inches.
Depth to Cr horizon - 40 to 60 inches.
A horizons - Hue: 10YR or 2.5Y
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1, 2 or 3
Clay content: 20 to 32 percent
Rock fragments: 15 to 60 percent--0 to 20 percent cobbles and stones, 15 to 40 percent pebbles
Reaction: pH 6.1 to 7.3
Bw horizons - Hue: 10YR or 2.5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3, 4 or 6
Texture: ashy coarse sandy loam, ashy sandy loam or ashy sandy clay loam
Clay content: 10 to 24 percent
Rock fragments: 35 to 60 percent--15 to 20 percent cobbles and stones, 20 to 40 percent pebbles
Reaction: pH 6.1 to 7.3
BC horizon - Hue: 10YR, or 2.5Y
Value: 6 or 7 dry; 4, 5 or 6 moist
Chroma: 1, 2 or 3
Texture: ashy sandy loam, ashy coarse sandy loam or ashy loamy coarse sand
Clay content: 5 to 18 percent
Rock fragments: 10 to 60 percent--0 to 20 percent cobbles and stones; 10 to 40 percent pebbles
Reaction: pH 7.4 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - hills and footslopes.
Elevation - 4,800 to 5,800 feet.
Slope - 15 to 35 percent.
Parent material - colluvium and residuum from rhyolitic welded tuff bedrock.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual air temperature - 39 to 44 degrees F.
Frost-free period - 70 to 90 days.
DRAINAGE AND PERMEABILITY: Well drained, moderately rapid permeability.
USE AND VEGETATION: Burrfoot soils are used primarily for rangeland and wildlife habitat. The potential native vegetation is mainly rough fescue, Idaho fescue, bluebunch wheatgrass and lupine with scattered limber pine, Douglas-fir and rocky mountain juniper.
DISTRIBUTION AND EXTENT: Burrfoot soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Deer Lodge County, Montana, 1999.
REMARKS: Soil interpretation record: MT1738. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 12 inches (A1 and A2 horizons); a cambic horizon from 12 to 29 inches (Bw1 and Bw2 horizons); a particle size control section from 10 to 40 inches (A2, Bw1, Bw2 and BC horizons); semi-consolidated rhyolite tuff at 48 inches (Cr horizon). Burrfoot soils have a frigid soil temperature regime and an ustic soil moisture regime. (Note: Areas in Deer Lodge County where this series has been mapped are moderately impacted from past smelter emissions and may contain significant levels of heavy metal contaminants in the surface horizons.)