LOCATION AUCHARD MT
Established Series
Rev. JAL/EMM
04/2012
AUCHARD SERIES
The Auchard series consists of moderately deep, well drained soils that formed in residuum derived from semiconsolidated shale, siltstone, and mudstone. These soils are on sedimentary plains and hills. Slopes are 0 to 15 percent. Mean annual precipitation is about 16 inches, and mean annual temperature is about 43 degrees F.
TAXONOMIC CLASS: Fine, mixed, superactive, frigid Typic Natrustalfs
TYPICAL PEDON: Auchard loam, rangeland (colors are for dry soil unless otherwise noted).
E--0 to 3 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; moderate very thin platy structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular and interstitial pores; many light gray (10YR 7/2) silt and sand skeletans on faces of plates; neutral (pH 6.8); abrupt smooth boundary. (2 to 6 inches thick)
Btn--3 to 9 inches; grayish brown (10YR 5/2) silty clay, dark grayish brown (10YR 4/2) moist; strong medium columnar structure; very hard, firm, sticky and plastic; common very fine roots; many very fine tubular pores; continuous distinct clay films on faces of peds; very dark grayish brown (10YR 3/2) moist, continuous clay films on faces of peds; silt and sand skeletans on tops of columns; moderately alkaline (pH 7.9); clear smooth boundary. (3 to 9 inches thick)
Btkn--9 to 24 inches; light brownish gray (10YR 6/2) silty clay, dark grayish brown (10YR 4/2) moist; moderate medium prismatic structure; very hard, firm, sticky and plastic; common very fine roots; many very fine tubular and interstitial pores; many distinct clay films on faces of peds; few fine seams and masses of lime; continuous faint coatings of lime on faces of peds; strongly effervescent; strongly alkaline (pH 8.6); gradual smooth boundary. (5 to 15 inches thick)
Bkyz--24 to 33 inches; light brownish gray (10YR 6/2) silty clay, dark grayish brown (10YR 4/2) moist; weak medium angular blocky structure; very hard, firm, sticky and plastic; common very fine roots; common very fine tubular and interstitial pores; common fine seams and masses of gypsum and other salts; disseminated lime; few fine masses of lime; strongly effervescent; strongly alkaline (pH 8.6); gradual smooth boundary. (8 to 15 inches thick)
Cr--33 to 60 inches; gray (5Y 6/1) semiconsolidated shale that crushes to a silty clay, gray (5Y 5/1) moist; moderately alkaline (pH 8.2).
TYPE LOCATION: Lewis and Clark County, Montana; 300 feet east and 100 feet north of the SW corner of Sec. 36, T. 19 N., R. 5 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Control section - 35 to 50 percent clay.
Depth to Btkn horizon - 5 to 15 inches (mainly 7 to 15 inches).
Depth to Bkyz horizon - 10 to 30 inches.
Depth to Cr layer - 20 to 40 inches.
E horizon
Hue - 10YR or 2.5Y
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 2 or 3
Texture - loam or clay loam
Clay content - 20 to 35 percent
Rock fragments - 0 to 10 percent gravel
Reaction - pH 6.1 to 7.3
Btn horizon
Hue - 10YR or 2.5Y
Value - 5 or 6 dry, 4 moist
Chroma - 2 or 3
Texture - clay or silty clay
Clay content - 35 to 50 percent
Rock fragments - 0 to 10 percent gravel
SAR - 13 to 30
Reaction - pH 7.9 to 8.6
Btkn horizon
Hue - 10YR or 2.5Y
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 2 or 3
Texture - silty clay loam, silty clay, or clay
Clay content - 35 to 50 percent
EC - 2 to 4 mmhos/cm
Rock fragments - 0 to 10 percent gravel
SAR - 13 to 30
Calcium carbonate equivalent - 5 to 15 percent
Reaction - pH 7.9 to 9.0
Bkyz horizon - Hue - 10YR or 2.5Y
Value - 4 or 5 moist
Chroma - 2 or 3
Texture - silty clay loam, clay loam, or silty clay
Clay content - 30 to 45 percent
EC - 4 to 16 mmhos/cm
Rock fragments - 0 to 10 percent gravel
SAR- 13 to 30
Calcium carbonate equivalent - 5 to 15 percent
Gypsum - 1 to 3 percent
Reaction - pH 7.9 to 9.0
COMPETING SERIES:
Lepner (MT) - does not have a paralithic contact above a depth of 60 inches.
GEOGRAPHIC SETTING:
Landform - sedimentary plains; hills.
Elevation - 4,200 to 5,500 feet.
Slope - 0 to 15 percent.
Parent material - formed in residuum from semi-consolidated shale, siltstone, and mudstone.
Climate - long, cold winters; moist springs; warm, dry summers.
Mean annual precipitation - 13 to 19 inches.
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 70 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Auchard soils are used mainly for rangeland and nonirrigated cropland. Potential native vegetation is mainly western wheatgrass, Idaho fescue, rough fescue, green needlegrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Auchard soils are not extensive in west-central Montana. MLRAs 44B and 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Liberty County, Montana, 1991; proposed in Lewis and Clark County, Montana, 1988.
REMARKS:
Soil interpretations record - MT1159.
Diagnostic horizons and features recognized in this pedon are
Ochric epipedon - from the surface to 3 inches, which is also an albic horizon (E horizon)
Natric horizon - from 3 to 24 inches (Btn and Btkn horizons)
Accumulation of lime - from 9 to 24 inches (Btkn horizon)
Accumulation of gypsum, lime and other salts from 24 to 33 inches (Bkyz horizon)
Paralithic contact - at a depth of 33 inches (Cr horizon)
Auchard soils have a frigid temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.