LOCATION BEENOM MT+CO WYEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, frigid Aridic Lithic Argiustolls
TYPICAL PEDON: Beenom loam, cultivated (colors are for dry soil unless otherwise noted).
Ap--0 to 7 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and many very fine roots; slightly alkaline; abrupt smooth boundary. (2 to 8 inches thick)
Bt1--7 to 13 inches; brown (10YR 4/3) clay loam, dark brown (10YR 3/3) moist; strong medium and fine blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and many very fine roots and tubular pores; many faint clay films on faces of peds; slightly alkaline; clear smooth boundary. (0 to 7 inches thick)
Bt2--13 to 18 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; weak medium prisms separating to strong fine blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots and tubular pores; many faint clay films on faces of peds and channers; 5 percent channers; slightly alkaline; clear smooth boundary. (2 to 5 inches thick)
R--18 to 30 inches; hard platy sandstone.
TYPE LOCATION: Stillwater County, Montana; 2,100 feet west and 800 feet south of the NE corner of sec. 19, T. 4 N., R. 20 E.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is between 4 and 12 inches. Ustic soil moisture regime that borders on aridic.
Soil temperature: 38 to 47 degrees F.
Mollic epipedon thickness: 7 to 15 inches.
Depth to lithic contact: 10 to 20 inches to sandstone bedrock
A horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 3, 4, or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: loam, fine sandy loam, clay loam, gravelly loam, or gravelly clay loam
Reaction: pH 6.1 to 7.8
Bt1 horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 3, 4, or 5 dry; 2, 3, or 4 moist
Chroma: 2 or 3
Texture: clay loam, fine sandy loam, or sandy clay loam
Clay content: 18 to 35 percent
Reaction: pH 6.1 to 8.4
Bt2 horizon:
Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: clay loam, fine sandy loam, or sandy clay loam
Clay content: 18 to 35 percent
Reaction: pH 5.6 to 8.4
There may be a continuous faint lime coating on the sandstone at the lithic contact.
COMPETING SERIES:
Beje (UT) - have ustic soil moisture regime and soil moisture control sections that are affected by precipitation that is fairly evenly distributed throughout the year with July and August being slightly wetter and June being slightly drier.
Berland (NM) - are less than 10 inches to a lithic contact; are slightly acid or medium acid throughout.
Bonjea (WY) - has more than 35 percent fine and coarser sand; formed in residuum and colluvium from granite and gneiss.
Cedric (MT) - has horizon of secondary carbonate accumulation; has a paralithic contact above the lithic contact.
Coni (CO) - formed in sediments of arkosic beds overlying hard cemented conglomerate, tuff or sandstone.
Connieo (MT) - has paralithic contact above the lithic contact; formed in residuum from granite.
Kiln (NM) - has stone size rock fragments throughout; has 5YR hues in the argillic horizon; formed in material derived from limestone.
Viewpoint (NM) - has 35 to 65 percent fine sand and coarser; formed in material derived from basalt; coarse fragments are dominantly basalt-breccia.
GEOGRAPHIC SETTING:
Landform - bedrock-floored plains, hills, structural benches, and strath terraces.
Elevation - 2,800 to 6,200 feet.
Slope - 0 to 60 percent.
Parent material - residuum from sandstone or in alluvium or colluvium over the sandstone.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 19 inches.
Mean annual temperature - 38 to 45 degrees F.
Frost-free period - 70 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Rentsac and Tanna soils. Rentsac soils formed in similar materials but lack a mollic epipedon or an argillic horizon. Tanna soils have a paralithic contact at depths of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Beenom soils are used mainly for range. Potential vegetation is western wheatgrass, prairie junegrass, bluegrass, lupine, and sagebrush.
DISTRIBUTION AND EXTENT: Beenom soils are of moderate extent in central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Stillwater County, Montana, 1975.
REMARKS: Soil interpretations record: MT0177, MT0704, MT0258, MT0705, MT1423. Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: The zone from 7 to 18 inches. (Bt1 and Bt2 horizons)
Mollic epipedon: The zone from the soil surface to 7 inches. (Ap horizon)
Argillic horizon: The zone from 7 to 18 inches. (Bt1 and Bt2 horizons)
Lithic contact: The contact with sandstone bedrock at 18 inches.
Classification changed from Lithic Argiboroll to frigid Aridic Lithic Argiustoll 7/98.
Formatting and classification updated 7/98
Taxonomic version: Eighth Edition, 1998.