LOCATION BACBUSTER               MT

Established Series
Rev. GAR/JAL/EMM
05/2012

BACBUSTER SERIES


The Bacbuster series consists of moderately deep, well drained soils that formed in interbedded sandstone, siltstone, mudstone, and shale residuum. These soils are on sedimentary plains, hills and escarpments. Slopes are 2 to 45 percent. Mean annual precipitation is about 17 inches, and the mean annual temperature is about 41 degrees F.

TAXONOMIC CLASS: Fine, mixed, superactive, frigid Typic Argiustolls

TYPICAL PEDON: Bacbuster clay loam, in rangeland. (Colors are for dry soil unless otherwise noted).

A--0 to 4 inches; dark grayish brown (10YR 4/2) clay loam, very dark grayish brown (10YR 3/2) moist, moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common fine and few medium roots; slightly alkaline (pH 7.6); clear smooth boundary. (4 to 11 inches thick)

Bt1--4 to 9 inches; dark grayish brown (10YR 4/2) clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and very plastic; common very fine and fine and few medium roots; common distinct clay films on faces of peds and lining pores; 10 percent soft shale chips; slightly alkaline (pH 7.6); clear smooth boundary.

Bt2--9 to 15 inches; brown (10YR 5/3) clay loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and very plastic; few very fine and fine roots; common prominent clay films on faces of peds and lining pores; 20 percent soft shale chips; slightly alkaline (pH 7.6); clear smooth boundary. (combined thickness of Bt horizon is 8 to 28 inches thick)

Btk--15 to 25 inches; gray (10YR 5/1) clay loam, dark grayish brown (10YR 4/2) moist; moderate fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; common distinct clay films on faces of peds and lining pores; 25 percent soft shale chips; common fine masses of lime; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (0 to 12 inches thick)

Bk--25 to 36 inches; gray (10YR 5/1) silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; 50 percent soft shale chips; many medium threads of lime; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (8 to 21 inches thick)

Cr--36 to 60 inches; gray (10YR 5/1) semi-consolidated shale; few lime coatings on shale fragments.

TYPE LOCATION: Gallatin County, Montana; 1500 feet north and 1000 feet east of the southwest corner of sec. 27, T.5N., R.5E.

RANGE IN CHARACTERISTICS:

Soil temperature - 41 to 45 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 7 to 15 inches.
Depth to Cr horizon - 20 to 40 inches.

A horizon
Value - 4 or 5 dry
Chroma - 2 or 3
Texture - loam, clay loam or silty clay loam
Clay content - 25 to 35 percent
Rock fragments - 0 to 30 percent -- 0 to 20 percent gravel, 0 to 15 percent cobbles
Reaction - pH 6.1 to 7.8

Bt1 horizon
Value - 4 or 5 dry; 3 or 4 moist
Chroma - 2 or 3
Texture - clay loam, clay, silty clay loam or silty clay
Clay content - 35 to 50 percent
Rock fragments - 0 to 15 percent -- 0 to 10 percent gravel, 0 to 5 percent cobbles; 0 to 15 percent soft shale chips
Reaction - pH 6.6 to 7.8

Bt2 horizon
Hue - 7.5YR, 10YR or 2.5Y
Value - 4 or 5 dry
Chroma - 2, 3 or 4
Texture - clay loam, clay, silty clay loam, or silty clay
Clay content - 35 to 50 percent
Rock fragments: 0 to 15 percent -- 0 to 10 percent gravel,
0 to 5 percent cobbles; 0 to 25 percent soft shale chips
Reaction - pH 6.6 to 7.8

Btk horizon
Hue - 10YR or 2.5Y
Value - 4 or 5 dry
Chroma - 1, 2, 3 or 4
Texture - silty clay loam, clay loam
Clay content - 30 to 40 percent
Rock fragments: 0 to 15 percent -- 0 to 10 percent gravel, 0 to 5 percent cobbles; 0 to 30 percent soft shale chips
Calcium carbonate equivalent: 2 to 10 percent
Reaction - pH 7.4 to 8.4

Bk horizon
Hue - 10YR or 2.5Y
Value - 5, 6 or 7 dry
Chroma - 1, 2, 3 or 4
Texture - loam, silty clay loam, clay loam
Clay content - 25 to 40 percent
Rock fragments - 0 to 25 percent -- 0 to 20 percent gravel, 0
to 5 percent cobbles; 0 to 60 percent soft shale chips
Calcium carbonate equivalent - 5 to 15 percent
Reaction - pH 7.4 to 8.4

COMPETING SERIES:

Alder (MT) - does not have a Btk horizon; has an ustic bordering on udic moisture regime.

Bigbear (MT) - does not have a paralithic contact above 60 inches.

Billman (MT) - does not have horizon of secondary carbonate accumulation.

Charo (NM) - has a lithic contact of basalt at 20 to 40 inches; does not have horizons of secondary carbonate accumulation.

Darret (MT) - has hue of 7.5YR or redder throughout.

Durston (MT) - does not have a paralithic contact above 60 inches; has a calcic horizon.

Microy (NM) - has a lithic contact of basalt at 20 to 40 inches; does not have horizons of secondary carbonate accumulation.

Mishakal (MT) - does not have horizons of secondary carbonate accumulation.

Pino (NM) - does not have horizons of secondary carbonate accumulation.

Roaringlion (MT) - does not have a paralithic contact above 60 inches.

Turkeysprings (NM) - does not have a paralithic contact above 60 inches.

Wilcoxson (NM) - has a lithic contact at 40 to 60 inches.

GEOGRAPHIC SETTING:

Landform - sedimentary plains, hills and escarpments.
Elevation - 4,200 to 6,500 feet.
Slope - 2 to 45 percent.
Parent material - interbedded shale, siltstone, mudstone and sandstone residuum
Climate - Long cold winters, moist springs, warm summers
Mean annual precipitation - 15 to 20 inches.
Mean annual air temperature - 39 to 43 degrees F.
Frost-free period - 70 to 115 days.

GEOGRAPHICALLY ASSOCIATED SOILS: None listed.

DRAINAGE AND PERMEABILITY: Well drained; slow permeability.

USE AND VEGETATION: Bacbuster soils are used mainly for rangeland, cropland and wildlife habitat. Potential native vegetation may include bluebunch wheatgrass, Idaho fescue, Columbia needlegrass, western wheatgrass, phlox, lupine, sagebrush as well other grasses, forbs and woody shrubs.

DISTRIBUTION AND EXTENT: Bacbuster soils are of extensive in southwestern Montana. MLRAs 43B, 44B, and 46.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Gallatin County, Montana, 1997.

REMARKS:
Soil interpretation record: MT1642.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from the surface to 9 inches (A, Bt1 horizons)
Argillic horizon - from 4 to 25 inches which is also the particle size control section (Bt1, Bt2, and Btk)
Horizons of secondary carbonate accumulation - from 15 to 36 inches (Btk and Bk horizons
Paralithic contact - at 36 inches (Cr horizon)

Bacbuster soils have a frigid temperature regime and an ustic moisture regime.


National Cooperative Soil Survey
U.S.A.