LOCATION LINWELL MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Entic Haplustolls
TYPICAL PEDON: Linwell silty clay loam, cultivated field (colors are for dry soil unless otherwise noted).
Ap--0 to 6 inches; dark grayish brown (2.5Y 4/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; the surface 1 inch has moderate fine granular structure, and the lower 5 inches has moderate fine and very fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many fine and very fine roots and few medium roots; many fine and very fine pores; slightly effervescent; slightly alkaline (pH 7.7); clear wavy boundary. (4 to 12 inches thick)
Bw--6 to 11 inches; grayish brown (2.5Y 5/2) silty clay loam, dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure parting to moderate medium and fine subangular blocky; hard, friable, moderately sticky and moderately plastic; many fine and very fine roots and few medium and coarse roots; many fine and very fine pores and few medium pores; few worm casts; slightly effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (5 to 16 inches thick)
Bk1--11 to 15 inches; grayish brown (2.5Y 5/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to moderate fine subangular blocky; hard, friable, moderately sticky and moderately plastic; many fine and very fine roots and few medium and coarse roots; many fine and very fine pores and few medium pores; few worm casts; common fine and very fine masses of lime; strongly effervescent; slightly alkaline (pH 7.8); clear wavy boundary. (3 to 11 inches thick)
Bk2--15 to 28 inches; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to moderate medium and fine subangular blocky; hard, friable, moderately sticky and moderately plastic; common fine and very fine roots and few medium and coarse roots; many fine and very fine pores and few medium and coarse pores; few worm casts; few medium masses of lime; strongly effervescent; moderately alkaline (pH 7.9); gradual wavy boundary. (8 to 20 inches thick)
Bk3--28 to 39 inches; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; weak medium prismatic structure; very hard, friable, moderately sticky and moderately plastic; moderate fine and very fine roots and few medium and coarse roots; many fine and very fine pores and few medium and coarse pores; few worm casts; common medium masses of lime; strongly effervescent; moderately alkaline (pH 7.9); diffuse wavy boundary. (11 to 15 inches thick)
C--39 to 67 inches; light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; few distinct yellowish brown (10YR 5/6) mottles; massive; very hard, friable, moderately sticky and moderately plastic; few fine and very fine roots; many fine and very fine pores and few medium pores; few fine masses and seams of lime; strongly effervescent; moderately alkaline (pH 7.9).
TYPE LOCATION: Fergus County, Montana; 590 feet west and 60 feet south of the NE corner of sec. 15, T. 18 N., R. 15 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches; moist in all or some parts April through July and mid-September through November, frozen December through March.
Mollic epipedon thickness - 7 to 16 inches.
A horizon - Hue: 10YR or 2.5Y
Value: 2 or 3 moist
Chroma: 1 or 2
Texture: silty clay loam, clay loam, or silty clay
Clay content: 30 to 45 percent
Rock fragments: 0 to 15 percent--0 to 5 percent stones and cobbles; 0 to 15 percent pebbles
Reaction: pH 6.6 to 7.8
Bw horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: silty clay loam, clay loam, or silty clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 15 percent pebbles
Reaction: pH 7.4 to 8.4
Bk horizons - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: silty clay loam, clay loam, or silty clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 15 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
A BCk horizon is allowed.
C horizons - Hue: 7.5YR, 10YR through 5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Mottles: none to few
Texture: silty clay loam, clay loam, or silty clay
Clay content: 35 to 45 percent
Rock fragments: 0 to 15 percent pebbles
Calcium carbonate equivalent: 5 to 12 percent
Reaction: pH 7.9 to 8.4
Accumulation of gypsum is allowed below a depth of 24 inches.
COMPETING SERIES:
Winifred (MT) - are 20 to 40 inches deep to a paralithic contact.
GEOGRAPHIC SETTING:
Landform - stream terraces, alluvial fans, hills, escarpments, and plains.
Elevation - 2,700 to 6,200 feet.
Slope - 0 to 45 percent.
Parent material - clayey alluvium from mixed sources of material.
Climate - long, cold winters; moist springs; and hot summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual air temperature - 39 to 45 degrees F.
Frost-free period - 70 to 125 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Linwell soils are used for rangeland, dryland and irrigated cropland, hayland, and pastureland. The potential native vegetation is mainly western wheatgrass, prairie junegrass, blue grama, green needlegrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Central and eastern Montana. Linwell soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Fergus County, Montana, 1979.
REMARKS: Soil interpretation record: MT0313. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 7 inches (mixed) (Ap, Bw horizons); a cambic horizon from 6 to 11 inches (Bw horizon); horizons of secondary carbonate accumulations from 11 to 39 inches (Bk1, Bk2, Bk3 horizons); a particle-size control section from 10 to 40 inches. Linwell soils have a frigid temperature regime and an ustic moisture regime.