LOCATION BEAUVAIS MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Aridic Argiustolls
TYPICAL PEDON: Beauvais silty clay loam, in cropland. (Colors are for dry soil unless otherwise noted)
Ap--0 to 5 inches; grayish brown (10YR 5/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; weak coarse granular structure; hard, friable, sticky and plastic; neutral (pH 7.0); abrupt smooth boundary. (3 to 5 inches thick)
Bt--5 to 9 inches; brown (10YR 5/3) silty clay, dark brown (10YR 3/3) moist; moderate medium prismatic structure parting to moderate medium angular blocky; hard, firm, sticky and plastic; continuous distinct dark grayish brown (10YR 4/2) clay films on faces of peds, common faint clay films in pores and bridging few sand grains; many very fine and few fine tubular pores; slightly alkaline (pH 7.6); clear wavy boundary. (3 to 5 inches thick)
Bk1--9 to 16 inches; light gray (2.5Y 7/2) silty clay loam, light olive brown (2.5Y 5/3) moist; weak coarse prismatic structure parting to weak coarse and medium subangular blocky; hard, friable, sticky and plastic; many very fine tubular pores; strongly effervescent; few fine faint masses of lime; moderately alkaline (pH 8.2); gradual wavy boundary.
Bk2--16 to 30 inches; light brownish gray (2.5Y 6/2) silty clay loam, light olive brown (2.5Y 5/3) moist; weak coarse subangular blocky structure; hard, friable, sticky and plastic; many very fine tubular pores; strongly effervescent common large masses of lime; moderately alkaline (pH 8.4) gradual wavy boundary. (Combined Bk horizons 15 to 30 inches thick)
C--30 to 60 inches; light yellowish brown (2.5Y 6/3) silty clay loam, grayish brown (2.5Y 5/2) moist; massive; hard, firm, sticky and plastic; many very fine tubular pores; strongly effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Big Horn County, Montana; 500 feet east and 100 feet south of W 1/4 corner, sec 2, T. 3 S., R. 34 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 48 to 50 degrees F.
Mollic epipedon thickness - 7 to 10 inches (may include Bt horizon).
Control section - 27 to 35 percent clay, less than 15 percent fine or coarser sand.
Depth to Bk horizon - 6 to 10 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 moist
Chroma: 2 or 3
Texture, less than 2 mm: silty clay loam
Clay content: 27 to 35 percent
Reaction; pH 6.6 to 7.3
Bt horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture, less than 2 mm: silty clay loam or silty clay
Clay content: 35 to 45 percent
Reaction: pH 7.4 to 7.8
Bk horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 or 3
Texture, less than 2 mm: silty clay loam
Clay content: 27 to 35 percent
Calcium Carbonate Equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.4
C horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture, less than 2 mm: silty clay loam
Clay content: 27 to 35 percent
Calcium Carbonate Equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES: These are the Brushton, Brussett, Norkool, Ralph, Vassett and Wass series. The Bt horizons of all these soils extend below depths of 10 inches. In addition, the Bt horizons of all these soils have less than 35 percent clay.
GEOGRAPHIC SETTING: The Beauvais soils are on fans, footslopes and high terraces. Elevations are 2,500 to 4,000 feet. Slopes range from 2 to 15 percent. These soils formed in calcareous silty clay loam loess. Mean annual precipitation is 15 to 19 inches. Mean annual air temperature is 47 to 49 degrees F. The frost-free period is 110 to 130 days.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: Beauvais soils are used mainly for dryland crops and as rangeland. Potential native vegetation is mainly western wheatgrass, green needlegrass, bluebunch wheatgrass and perennial forbs.
DISTRIBUTION AND EXTENT: Beauvais soils are of moderate extent in south-central Montana.
SERIES ESTABLISHED: Big Horn County, Montana, 1970.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
REMARKS: Soil Interpretations Record: MT0529. Physical and chemical properties of this soil are interpolated from data on Keiser soils reported in soil survey Investigations Report No. 7. Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 9 inches (Ap and Bt horizons); argillic horizon - the zone from 5 to 9 inches (Bt horizon); particle-size control section - the zone from 5 to 40 inches (Bt, Bk1, Bk2 and C horizons).