LOCATION DEGRAND MTEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Aridic Argiustolls
TYPICAL PEDON: Degrand loam in pasture. (Colors are for dry soil unless otherwise noted)
Ap--0 to 4 inches; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; moderate fine angular blocky structure parting to moderate fine granular; soft, very friable, nonsticky and nonplastic; many very fine roots; neutral (pH 7.0); abrupt smooth boundary. (3 to 7 inches thick)
Bt1--4 to 12 inches; brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; common very fine pores; common faint clay films on faces of peds and in pores; neutral (pH 7.2); clear smooth boundary.
Bt2--12 to 18 inches; brown (10YR 5/3) clay loam, dark brown (10YR 4/3) moist; moderate medium prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine pores; common faint clay films on faces of peds and in pores; neutral (pH 7.2); clear smooth boundary. (Combined Bt horizon 9 to 16 inches thick)
Bk--18 to 33 inches; light gray (2.5Y 7/2) loam, grayish brown (2.5Y 5/2) moist; weak medium prismatic structure; slightly hard, friable, slightly sticky and plastic; common very fine roots; common very fine pores; many medium masses of lime; violently effervescent; strongly alkaline (pH 8.6); clear smooth boundary. (8 to 17 inches thick)
2C--33 to 60 inches; light brownish gray (2.5Y 6/2) sand, dark grayish brown (2.5Y 4/2) moist; single grain; loose nonsticky and nonplastic; 10 percent pebbles; continuous faint lime coatings on surface of pebbles; strongly effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Prairie County, Montana; 200 feet east and 2,400 feet south of the NW corner of sec. 7, T. 11 N., R. 52 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 to 12 inches; dry in some part six-tenths or more of the cumulative days per year when the soil temperature at a depth of 20 inches is 41 degrees of higher.
Mollic epipedon thickness - 7 to 16 inches (includes part of the Bt horizon).
Depth to calcic horizon - 10 to 23 inches.
Depth to 2C horizon - 20 to 40 inches, but commonly is 28 to 37 inches.
Ap horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: fine sandy loam, sandy loam, loam, or clay loam
Clay content: 10 to 32 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Reaction: pH 6.6 to 7.8
Some pedons have an A horizon below the Ap horizon. Thin surface horizon of 2 to 4 inches thick having a dry value of 4 are allowed. These horizons when mixed to 7 inches have a dry value of 5.
Bt horizons - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: clay loam or sandy clay loam
Clay content: 20 to 35 percent (sand content 35 to 55 percent)
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Reaction: pH 6.6 to 8.4
Bk horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Texture: sandy clay loam, loam, or clay loam
Clay content: 15 to 30 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Electrical conductivity: less than 4 mmhos/cm
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 7.4 to 9.0
2C horizon - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: sand, coarse sand, fine sand, or loamy sand
Clay content: 0 to 5 percent
Rock fragments: 0 to 35 percent--0 to 5 percent cobbles, 0 to 30 percent pebbles
Calcium carbonate equivalent: 8 to 15 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES:
Attewan (MT) - have more than 35 percent rock fragments in the 2C horizon.
Beaverflat (MT) - do not have carbonates above a depth of 60 inches.
GEOGRAPHIC SETTING:
Landforms - stream terraces; alluvial fans; outwash plains, drainageways.
Elevations - 2,150 to 3,500 feet.
Slope- 0 to 8 percent.
Parent material - loamy alluvium or glaciofluvial deposits which are 20 to 40 inches deep over sand, fine sand, or loamy sand.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual temperature - 40 to 45 degrees F.
Frost-free period - 105 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained. Moderate permeability in the A and B horizons and rapid permeability in the 2C horizon. Runoff is negligible to medium depending on slope.
USE AND VEGETATION: Degrand soils are used mainly for nonirrigated crops. The potential native vegetation is western wheatgrass, prairie junegrass, green needlegrass, needleandthread, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Degrand soils are of moderate extent along the lower Yellowstone River and its tributaries.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Rosebud County Area and part of Big Horn County, Montana, 1986. Type location moved to Prairie County, Montana, in 1984.
REMARKS: Soil interpretation record: MT0263, MT0924.
Diagnostic horizons and features recognized in this pedon are: mollic epipedon - the zone from the surface of the soil to a depth of 12 inches (Ap and Bt1 horizons); argillic horizon - the zone from 4 to 18 inches (Bt1 and Bt2 horizons); calcic horizon - the zone from 18 to 33 inches (Bk horizon); particle-size control section - the zone from 4 to 40 inches (Bt1, Bt2, Bk and 2C horizons). Degrand soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.