LOCATION LEPNER MT
Tentative Series
Rev. LCB-DRS-EMM
10/2014
LEPNER SERIES
The Lepner series consists of very deep, well drained soils that formed in alluvium. These soils are on alluvial fans and stream terraces. Slopes are 0 to 4 percent. Mean annual precipitation is about 16 inches and mean annual air temperature is about 41 degrees F.
TAXONOMIC CLASS: Fine, mixed, superactive, frigid Typic Natrustalfs
TYPICAL PEDON: Lepner gravelly loam, 2 percent slope in non-irrigated cropland (colors are for dry soil unless otherwise noted).
E--0 to 6 inches; light brownish gray (10YR 6/2) gravelly loam, dark grayish brown (10YR 4/2) moist; moderate very thin platy structure; hard, very friable, moderately sticky and slightly plastic; common very fine roots; many very fine tubular and interstitial pores; many light gray (10YR 7/2) silt and sand skeletans on faces of peds; 20 percent gravel; moderately acid (pH 5.6); clear smooth boundary. (3 to 8 inches thick)
Bt--6 to 15 inches; brown (10YR 5/3) silty clay, brown (10YR 4/3) moist; strong medium columnar structure; very hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular pores; continuous distinct dark brown (10YR 3/3) moist clay films on faces of peds; silt and sand skeletans on tops of columns; slightly alkaline (pH 7.6); gradual smooth boundary. (7 to 15 inches thick)
Btkn--15 to 32 inches; light yellowish brown (10YR 6/4) silty clay, brown (7.5YR 4/4) moist; moderate medium prismatic structure; hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular and interstitial pores; common distinct clay films on faces of peds; common faint coatings of lime; strongly effervescent; strongly alkaline (pH 8.8); gradual smooth boundary. (10 to 20 inches thick)
Bnyz--32 to 60 inches; light yellowish brown (10YR 6/4) gravelly clay loam, brown (7.5YR 5/4) moist; weak medium and fine subangular blocky structure; hard, friable, moderately sticky and slightly plastic; few very fine roots; common very fine tubular and interstitial pores; 20 percent gravel; common fine seams and masses of gypsum and other salts; strongly alkaline (pH 8.6).
TYPE LOCATION: Meagher County, Montana; 2,600 feet north and 250 feet west of the SE corner of sec. 22, T. 8 N., R. 6 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 40 to 45 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to carbonates - 10 to 20 inches.
E horizon
Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2 or 3 dry or moist
Clay content: 20 to 27 percent
Rock fragments: 15 to 25 percent gravel
Reaction: pH 5.6 to 7.3
Bt horizon
Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 3, 4, or 5 moist
Chroma: 2, 3, or 4 dry or moist
Texture: clay or silty clay
Clay content: 40 to 50 percent
Rock fragments: 0 to 15 percent gravel
Sodium adsorption ratio: 3 to 13
Reaction: pH 7.4 to 8.4
Btkn horizon
Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4 dry or moist
Texture: clay, silty clay, or clay loam
Clay content: 35 to 45 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 5 to 10 percent
Sodium adsorption ratio: 13 to 20
Reaction: pH 8.5 to 9.0
Bnyz horizon
Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3, or 4 dry or moist
Texture: loam, clay loam, or silty clay loam
Clay content: 25 to 40 percent
Rock fragments: 0 to 25 percent gravel, 0 to 5 percent cobbles
Electrical conductivity: 4 to 10 mmhos/cm
Sodium adsorption ratio: 13 to 20
Gypsum: 1 to 2 percent
Calcium carbonate equivalent: 0 to 10 percent
Reaction: pH 8.5 to 9.0
COMPETING SERIES:
Auchard (MT) - has a paralithic contact of semi-consolidated shale at depths between 20 and 40 inches.
GEOGRAPHIC SETTING:
Landform - alluvial fans; stream terraces.
Elevation - 5,000 to 5,500 feet.
Slope - 0 to 4 percent.
Parent material - alluvium.
Climate - long, cold winters; moist springs; short, warm summers.
Mean annual precipitation - 15 to 19 inches, most of which falls during spring and early summers.
Mean annual air temperature - 38 to 43 degrees F.
Frost-free period - 70 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Lepner soils are used for rangeland and nonirrigated cropland. The potential native vegetation is mainly rough fescue, bluebunch wheatgrass, western wheatgrass, Idaho fescue, green needlegrass, Sandberg bluegrass, prairie junegrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Lepner soils are of small extent mainly in west-central Montana. MLRAs 43B, 44B, and 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Meagher County, Montana, 1992.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Albic horizon from the surface to 6 inches (E horizon)
Natric horizon with skeletans from 6 to 32 inches (Bt, Btkn horizons)
Accumulation of lime from 15 to 32 inches (Btkn horizon)
Accumulation of gypsum and other salts from 32 to 60 inches (Bnyz horizon)
Lepner soils have a frigid temperature regime and an ustic moisture regime.
Soil interpretation record: MT1415.
National Cooperative Soil Survey
U.S.A.