LOCATION BENZ MT+ND WYEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, frigid Aridic Ustorthents
TYPICAL PEDON: Benz clay loam, grassland (colors are for dry soil unless otherwise noted).
A1--0 to 1/8 inch; light gray (2.5Y 7/2) clay loam, grayish brown (2.5Y 5/2) moist vesicular surface crust. (0 to 1/2 inch thick)
A2--1/8 to 2 inches; grayish brown (2.5Y 5/2) clay loam, very dark grayish brown (2.5Y 3/2) moist; weak fine granular structure; very hard, friable, sticky and plastic; disseminated lime; slightly effervescent; strongly alkaline (pH 8.8); clear boundary. (1 to 4 inches thick)
C1--2 to 12 inches; light brownish gray (2.5Y 6/2) clay loam, dark grayish brown (2.5Y 4/2) moist; massive; extremely hard, friable, sticky and plastic; common fine and very fine pores, slightly effervescent; strongly alkaline (pH 8.8); disseminated lime; diffuse wavy boundary. (8 to 12 inches thick)
C2--12 to 24 inches; light brownish gray (2.5Y 6/2) clay loam stratified with lenses of loam, dark grayish brown (2.5Y 4/2) moist; massive; extremely hard; friable, sticky and plastic; few fine and very fine roots and pores; disseminated lime; few fine threads and masses of lime; strongly effervescent, very strongly alkaline (pH 9.6); diffuse boundary. (7 to 14 inches thick)
C3--24 to 66 inches; light brownish gray (2.5Y 6/2) loam stratified with thin lenses of fine sandy loam, dark grayish brown (2.5Y 4/2) moist; massive; extremely hard, friable, sticky and slightly plastic; few roots and pores; disseminated lime; few fine threads of lime; few fine threads of gypsum; strongly effervescent; very strongly alkaline (pH 9.6).
TYPE LOCATION: Cascade County, Montana; about 2,520 feet south and 1,400 feet west of NE corner of sec. 8, T. 21 N., R. 4 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 47 degrees F.
Moisture control section - between 4 and 12 inches, dry in all parts between four-tenths and five-tenths of the cumulative days per year when the soil temperature at a depth of 20 inches is higher than 41 degrees F.
The surface is crusted and is hard or very hard when dry.
Some pedons have a Ck horizon.
A horizons - Hue: 2.5Y or 10YR
Value: 5, 6, or 7 dry; 3, 4, or 5 moist
Chroma: 2 or 3
Texture: loam, clay loam, silt loam, or silty clay loam
Clay content: 18 to 35 percent
EC: 4 to 8 mmhos/cm
SAR: 0 to 13
Calcium carbonate equivalent: 1 to 10 percent
Reaction: pH 7.4 to 9.6
C horizons - Hue: 5Y, 2.5Y, 10YR
Value: 5, 6, 7, or 8 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Texture: loam, clay loam, silt loam, or fine sandy loam consisting of strata of silt, silty clay loam, sandy loam
Clay content: 15 to 35 percent
Rock fragments: 0 to 35 percent pebbles
EC: 8 to 16 mmhos/cm
SAR: 13 to 30
Calcium carbonate equivalent: 1 to 15 percent
Gypsum content: 1 to 5 percent
Reaction: pH 8.5 to 9.6
COMPETING SERIES:
Hillon (MT) - has a horizon of secondary carbonates below 3 to 10 inches; formed in till that has a bulk density of 1.55 grams/cubic centimeter or greater.
Mussel (MT) - does not have an SAR of 13 or greater in the control section; has an EC of less than 4 in the control section.
Patent (ND) - does not have an SAR of 13 or greater or an EC of 8 or greater in the control section.
GEOGRAPHIC SETTING:
Landform - alluvial fans, hills, sedimentary plains, and stream terraces.
Elevation - 1,900 to 5,000 feet.
Slope- 0 to 15 percent.
Parent material - alkaline calcareous stratified loamy alluvium.
Climate - long, cold, dry winters; moist springs; moist summers.
Mean annual precipitation - 10 to 17 inches.
Mean annual temperature - 39 to 45 degrees F.
Frost-free period - 90 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Benz soils are used mainly for range. Potential native vegetation is mainly western wheatgrass, alkali sacaton, plains reedgrass, needleandthread, inland saltgrass, Nuttall saltbush, and greasewood.
DISTRIBUTION AND EXTENT: Benz soils are moderately extensive and widely distributed throughout Montana and possibly adjacent states.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Dawson County, Montana, 1971.
REMARKS: Soil interpretations record: MT0003, MT1288, MT1634. Diagnostic horizons and features recognized in this pedon are: a vesicular crust from 0 to 1/8 inch thick (A1 horizon); an ochric epipedon from the soil surface to 7 inches (A1, A2, part of C1 horizon); a particle-size control section from 10 to 40 inches (part of C1, C2, and part of C3 horizons). The Benz soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.