LOCATION ALDER MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Alder clay loam, grassland (colors are for dry soil unless otherwise noted).
A1--0 to 3 inches; dark gray (10YR 4/1) loam, very dark brown (10YR 2/1) moist; moderate fine granular structure; slightly hard, very friable, slightly sticky and plastic; many fine and very fine, common medium roots; less than 5 percent pebbles; neutral (pH 6.8); clear smooth boundary.
A2--3 to 9 inches; dark gray (10YR 4/1) clay loam, very dark brown (10YR 2/1) moist; weak medium prismatic structure parting to moderate fine subangular blocky; hard, friable, sticky and plastic; many fine and very fine, common medium roots; many fine and very fine, few medium pores; less than 5 percent pebbles; neutral (pH 6.8); abrupt smooth boundary. (A horizons are 6 to 14 inches thick.)
Bt1--9 to 15 inches; brown (10YR 5/3) silty clay, dark brown (10YR 4/3) moist; weak medium prismatic structure parting to strong fine subangular blocky; very hard, friable, sticky and plastic; many fine and very fine, common medium roots; many fine and very fine, few medium pores; continuous faint clay films on faces of peds; less than 5 percent pebbles; few worm casts; slightly alkaline (pH 7.4); gradual wavy boundary.
Bt2--15 to 21 inches; light yellowish brown (10YR 6/4) silty clay, yellowish brown (10YR 5/4) moist; weak medium prismatic structure parting to strong fine subangular blocky; very hard, firm, sticky and very plastic; common fine and very fine roots; many fine and very fine pores; continuous faint clay films on faces of peds; 5 percent angular sandstone pebbles; few worm casts; slightly alkaline (pH 7.4); clear wavy boundary.
Bt3--21 to 26 inches; very pale brown (10YR 7/4) clay loam, light yellowish brown (10YR 6/4) moist; moderate fine subangular blocky structure; very hard, friable, sticky and plastic; common fine and very fine, few medium roots; many fine and very fine, few medium pores; continuous faint clay films on faces of peds; 10 percent angular sandstone pebbles; moderately alkaline (pH 8.0); clear irregular boundary. (Bt horizons are 7 to 20 inches thick.)
Bk--26 to 31 inches; yellow (10YR 7/6) clay loam, brownish yellow (10YR 6/6) moist; moderate medium and fine subangular blocky structure; hard, firm, sticky and plastic; many fine and very fine roots; many fine and very fine, few medium pores; 10 percent angular sandstone pebbles; common fine seams and masses of lime; strongly effervescent, moderately alkaline (pH 8.0). (4 to 12 inches thick)
Cr--31 to 60 inches; white (5Y 8/1) consolidated shale interbedded with sandstone.
TYPE LOCATION: Fergus County, Montana; about 750 feet east and 350 feet north of SW corner of sec. 6, T. 14 N., R. 19 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 39 to 45 degrees F.
Mollic epipedon thickness - 7 to 16 inches.
Depth to Cr horizon - 20 to 40 inches to interbedded shale, sandstone, and mudstone.
A horizon - Value: 3 or 4 dry; 2 or 3 moist
Texture: clay loam or silty clay loam
Clay content: 27 to 40 percent
Rock fragments: 0 to 35 percent--0 to 30 percent stones; 0 to 30 percent cobbles; 0 to 15 percent pebbles
Reaction: pH 6.1 to 7.8
Bt1 and Bt2 horizon - Hue: 2.5YR to 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 1, 2, 3, or 4
Texture: silty clay, clay, or clay loam
Clay content: 35 to 60 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles; 0 to 15 percent pebbles
Reaction: pH 6.6 to 7.8
Bt3 and Bk horizon - Hue: 2.5YR to 5Y
Value: 4, 5 or 6 dry; 3, 4 or 5 moist
Chroma: 2, 3, or 4
Texture: clay loam, silty clay loam, sandy clay or clay
Clay content: 30 to 50 percent
Rock fragments: 0 to 30 percent--0 to 10 percent cobbles; 0 to 25 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Bigbear (MT) - does not have a paralithic contact above 60 inches.
Durston (MT) - does not have a paralithic contact above 60 inches.
GEOGRAPHIC SETTING:
Landform- sedimentary plains, hills , escarpments.
Elevation- 4,100 to 5,800 feet.
Slope- 2 to 45 percent.
Parent material - clayey materials weathered from consolidated shale, sandstone, and mudstone.
Climate- long, cold winters; moist springs; warm summers.
Mean annual precipitation - 18 to 24 inches.
Mean annual air temperature - 37 to 43 degrees F.
Frost-free period - 80 to 110 days.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Alder soils are used as cropland, pastureland, and rangeland. Potential native vegetation is mainly rough fescue, bluebunch wheatgrass, green needlegrass, western wheatgrass, Idaho fescue, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Alder soils are of moderate extent in central and southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Judith Basin Area, Montana, 1962.
REMARKS: Soil Interpretations Records: MT0358 and MT0770. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 9 inches (A1 and A2 horizons); an argillic horizon which is the particle-size control section from 9 to 26 inches (Bt1, Bt2, and Bt3 horizons); a horizon of secondary carbonate accumulation from 26 to 31 inches (Bk horizon). Alder soils have a frigid temperature regime and an ustic moisture regime bordering on udic.