LOCATION BEW MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Torrertic Haplustalfs
TYPICAL PEDON: Bew clay - cultivated. (Colors are for dry soil unless otherwise noted)
Ap--0 to 6 inches; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate medium and fine granular structure; hard, firm, very sticky, very plastic; neutral (pH 6.8); clear smooth boundary.
Bt1--6 to 11 inches; grayish brown (2.5Y 5/2) clay, olive brown (2.5Y 4/3) moist; moderate medium prismatic structure that separates to moderate medium and fine blocks; very hard, very firm, very sticky, very plastic; distinct film on faces of peds and walls of pores; neutral (pH 7.1); clear wavy boundary.
Bt2--11 to 17 inches; light brownish gray (2.5Y 6/2) clay, dark grayish brown (2.5Y 4/2) moist; weak medium blocky structure; very hard, very firm, very sticky, very plastic; distinct film on faces of peds and on walls of pores; weak effervescence, with few carbonate segregations; moderately alkaline; gradual wavy boundary. (Combined Bt horizons 7 to 20 inches thick)
Bk1--17 to 22 inches; light brownish gray (2.5Y 6/2) clay, grayish brown (2.5Y 5/2) moist; weak medium blocky structure; very hard, very firm, very sticky, very plastic; moderate effervescence with few masses of carbonates; moderately alkaline; gradual wavy boundary. (0 to 7 inches thick)
Bk2--22 to 32 inches; olive gray (5Y 5/2) clay, olive (5Y 4/3) moist; massive; very hard, very firm, very sticky, very plastic; strong effervescence; common threads and fine masses of carbonate; moderately alkaline; gradual wavy boundary. (5 to 16 inches thick)
C2--32 to 60 inches; olive gray (5Y 5/2) clay loam, olive (5Y 4/3) moist; massive; very hard, firm, very sticky, very plastic; moderately alkaline; strong effervescence; few small pebbles increasing to 30 percent in the lower part.
TYPE LOCATION: Yellowstone County, Montana; 930 feet west and 33 feet south of NE corner of sec. 32, T.2N., R.25E.
RANGE IN CHARACTERISTICS: The depth to lime ranges from 11 to 20 inches thick. Thickness of clay textures is 30 or more inches. The clay is dominantly smecitite with a CEC of 50 to 70 millequivalents per 100 grams of carbonate-free clay. Organic matter averages 2 percent in the upper 15 inches. The soils are usually dry when not frozen unless they are irrigated.
The A horizon has hue of 10YR or 2.5Y, value of 5 or 6 dry, and chroma of 2 or 3. It is clay, silty clay loam, clay loam or silty clay. It is neutral. A 3 to 5 inch thick clay loam A1 horizon that has value of 6 dry and 4 moistis in some pedons.
The Bt horizon has hue of 10YR or 2.5Y and chroma of 2 or 3. The upper few inches of the Bt horizon has value of 4 or 5 coated and 5 crushed, and 3 or 4 moist, coated or crushed. The Bt horizon has 50 to 60 percent clay, and has 10 to 15 percent more clay than the A horizon and from 5 to 10 percent more clay than in the upper C horizon. It is clay or silty clay. It is slightly alkaline or moderately alkaline. It has moderate to strong prismatic or blocky structure that separates to fine blocks.
The Bk and C horizons have hue of 2.5Y or 5Y and chroma of 2 or 3. They are slightly alkaline or moderately alkaline. The Bk horizon is clay and has few to common threads and masses of segregated lime. The C horizon is clay loam. Contrasting strata of transported material or of shale occur below depths of 40 inches in some pedons.
COMPETING SERIES: These are the Archuleta, Arnhart, Baca, Big horn, Briggsdale, Hesper, Hinman, Malposa, Renohill, Thurlow and Ulm series as previoulsy classified. Archuleta soils have less than 15 percent fine or coarser sand in the B2t and C horizons and have 35 to 50 percent clay in the Bt horizon. Arnhart soils have CEC of 150 to 300 millequivalents per 100 grams of clay and have less than 50 percent clay in the Bt horizon. Baca, Hesper, Renohill, Thurlow and Ulm soils have 35 to 50 percent clay in the Bt horizon. In addition, Renohill soils have shale bedrock at depth of about 30 inches and Hesper soils have silt loam C horizons. Big horn and Briggsdale soils have an abrupt boundary between the A horizons and the clay Bt horizons. Hinman soils have less than one percent organic matter in the upper 15 inches of the pedon. Malposa soils have mixed clay types with less than 50 percent cation exchange capacity and have sandstone or shale bedrock.
SETTING: The Bew soils are on uplands and in valleys on deep calcareous clay materials. The climate is cool semiarid with mean annual air temperatures of 45 degrees to 50 degrees F.; mean summer air temperatures of 65 degrees to 70 degrees F.; and average annual rainfall of 10 to 14 inches. The frost free period is 115 to 130 days.
PRINCIPAL ASSOCIATED SOILS: These are the Allentine, Galata and Kyle soils and the competing Thurlow soils. Allentine and Galata soils have natric horizons and have much gray silt coating peds in the epipedon and in the Galata soils this continues into the upper part of the argillic horizon. Kyle soils lack argillic horizons.
DRAINAGE AND PERMEABILITY: Well-drained; slow permeability.
USE AND VEGETATION: Used primarily for irrigated and nonirrigated cropland. Native vegetation is mainly western wheatgrass, blue grama and sagebrush.
DISTRIBUTION AND EXTENT: Throughout southeastern Montana. It is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Treasure County, Montana, 1963.
REMARKS: Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface of the soil to a depth of 6 inches (Ap horizon); argillic horizon - the zone from 6 to 17 inches (Bt1 and Bt2 horizons).