LOCATION BONFRI MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Haplustalfs
TYPICAL PEDON: Bonfri loam, cultivated (colors are for dry soil unless otherwise noted).
Ap--0 to 7 inches; grayish brown (10YR 5/2) loam, dark grayish brown (10YR 4/2) moist; weak fine granular structure; soft, friable, nonsticky and nonplastic; neutral; clear wavy boundary. (4 to 8 inches thick)
Bt--7 to 23 inches; grayish brown (10YR 5/2) clay loam, brown (10YR 4/3) moist; weak prismatic separating to moderate medium and fine subangular blocky structure; slightly hard, friable, sticky and plastic; few fine and very fine roots and pores; common faint clay films on faces of peds; neutral; gradual wavy boundary. (9 to 22 inches thick)
Bk1--23 to 28 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; weak fine prismatic structure; slightly hard, friable, sticky and plastic; few very fine roots and pores; 1 percent sandstone pebbles; many fine threads and seams of lime; many distinct lime coatings on pebbles; strongly effervescent; moderately alkaline; gradual wavy boundary.
Bk2--28 to 36 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, friable, sticky and plastic; few very fine roots and common pores; 5 percent pebbles; common fine masses and seams of lime; many distinct coatings on pebbles; strongly effervescent; moderately alkaline; gradual wavy boundary. (Combined Bk horizons 2 to 20 inches thick)
Cr--36 to 60 inches; semiconsolidated interbedded shale and sandstone.
TYPE LOCATION: Stillwater County, Montana; 200 feet west and 80 feet north of the SE corner of sec. 12, T. 2 S., R. 20 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Control section - 27 to 35 percent clay and less than 35 percent fine and coarser sand.
Depth to bedrock - 20 to 40 inches.
Depth to Bk horizon - 13 to 30 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: loam, silt loam, sandy loam, fine sandy loam, or clay loam
Clay content: 10 to 32 percent
Rock fragments: 0 to 5 percent pebbles
Reaction: pH 6.6 to 7.8
Bt horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3 or 4
Texture: clay loam, silty clay loam, or sandy clay loam
Clay content: 27 to 35 percent
Sand content: greater than 15 percent fine sand or coarser
Rock fragments: 0 to 5 percent pebbles
Reaction: pH 6.6 to 7.8
Some pedons have a Btk horizon.
Bk horizons - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Texture: clay loam, loam, sandy clay loam
Clay content: 20 to 32 percent
Rock fragments: 0 to 10 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Bondoe (MT) - does not have a paralithic contact; is loamy-skeletal below the argillic horizon; has 15 to 35 percent channers in the argillic horizon.
Fattig (MT) - are moderately deep to hard sandstone.
Ferball (MT) - does not have a paralithic contact; is calcareous to the surface; has hues of 7.5YR and redder throughout the soil.
Foreleft (MT) - does not have a paralithic contact; has moderate permeability.
Raghorn (MT) - does not have horizons of secondary calcium carbonate.
GEOGRAPHIC SETTING:
Landform - alluvial fans, sedimentary plains, ridges and hills.
Elevation - 2,500 to 5,000 feet.
Slope- 0 to 25 percent.
Parent material - alluvium, colluvium or residuum from interbedded sandstone and shale.
Climate - long, cold winters; moist springs; warm summers.
Mean annual air temperature - 40 to 45 degrees F.
Mean annual precipitation - 10 to 16 inches.
Frost-free period - 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: The Bonfri soils are used for irrigated and dryland farming with main crops of wheat, barley, alfalfa, and mixed hay. They are also used for range. Potential native vegetation is mainly western wheatgrass, needleandthread, bluebunch wheatgrass, blue grama, green needlegrass, threadleaf sedge, prairie junegrass, annual forbs, and woody plants.
DISTRIBUTION AND EXTENT: The Bonfri series is of moderate extent and is distributed throughout the plains of southeastern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Stillwater County, Montana, 1975.
REMARKS: Soil interpretations record: MT0182. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon to a depth of 7 inches (Ap horizon); an argillic horizon from 7 to 23 inches (Bt horizon); a particle-size control section from 7 to 23 inches (Bt horizon); accumulation of secondary carbonates from 23 to 36 inches (Bk1 and Bk2 horizons). The Bonfri soil has a frigid temperature regime and an ustic moisture regime that borders on aridic.