LOCATION WARHORSE MTEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, frigid, shallow Aridic Haplustalfs
TYPICAL PEDON: Warhorse loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 4 inches; pale brown (10YR 6/3) loam, brown (10YR 5/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots; neutral (pH 7.0); clear smooth boundary. (2 to 5 inches thick)
Bt--4 to 11 inches; brown (10YR 4/3) silty clay loam, dark brown (10YR 3/3) moist; weak medium prismatic structure parting to moderate fine subangular blocky; hard, firm, sticky and plastic; common fine and very fine roots; common distinct clay skins on faces of peds; slightly alkaline (pH 7.4); clear smooth boundary. (5 to 10 inches thick)
BC-11 to 18 inches; brown (10YR 4/3) silty clay loam; dark brown (10YR 3/3) moist; massive; slightly hard, friable, sticky and plastic; common very fine roots; 75 percent soft shale fragments; slightly alkaline (pH 7.8); gradual smooth boundary. (3 to 8 inches thick)
Cr--18 to 60 inches; semiconsolidated interbedded shale and sandstone; slightly alkaline (pH 7.6)
TYPE LOCATION: Petroleum County, Montana; 2,600 feet east and 200 feet south of the northwest corner of section 14, T. 15 N, R. 26 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to Cr horizon - 10 to 20 inches.
A horizon - Hue: 10YR or 2.5Y Value: 5 or 6 dry; 4 or 5 moist Chroma: 2 or 3 Texture: loam or clay loam Clay content: 18 to 35 percent Rock fragments: 0 to 15 percent--0 to 5 percent cobbles; 0 to 10 percent pebbles EC: 0 to 2 mmhos/cm Reaction: pH 6.6 to 7.8
Bt horizon - Hue: 10YR or 2.5Y Value: 4 or 5 dry; 3 or 4 moist Chroma: 2 or 3 Texture: clay loam, silty clay loam, or silty clay Clay content: 35 to 45 percent Rock fragments: 0 to 10 percent pebbles EC: 0 to 2 mmhos/cm Reaction: pH 6.6 to 7.8
BC horizon - Hue: 10YR or 2.5Y Value: 4, 5, or 6 dry; 3, 4, or 5 moist Chroma: 2 or 3 Texture: clay loam, silty clay loam, or silty clay Clay content: 30 to 45 percent Rock fragments: 50 to 90 percent--50 to 80 percent soft shale fragments; 0 to 10 percent hard sandstone fragments EC: 0 to 4 mmhos/cm Reaction: pH 6.6 to 8.4 NOTE: Some pedons have a thin accumulation of secondary carbonates at the shale contact.
Cr horizon--Semiconsolidated sedimentary beds consisting of interbedded shale and fine grained sandstone. Extremely hard or very hard when dry and extremely firm or very firm when moist.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - sedimentary plains and hills.
Elevation - 1,900 to 4,200 feet.
Slope- 0 to 15 percent.
Parent material - material derived from semiconsolidated interbedded shale and sandstone.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual temperature - 40 to 45 degrees F.
Frost-free period - 105 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained, slow permeability.
USE AND VEGETATION: Used for rangeland. The potential native vegetation is dominantly bluebunch wheatgrass, western wheatgrass, needleandthread, and big sagebrush.
DISTRIBUTION AND EXTENT: The series is of limited extent in central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Petroleum County, Montana, 1989.
REMARKS: Soil Interpretation Record: MT1110.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - from the soil surface to 4 inches (A horizon); argillic horizon - from 4 to 11 inches (Bt horizon); paralithic contact - at 18 inches (Cr horizon); particle-size control section - from 4 to 11 inches (Bt horizon). Warhorse soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
Series will be reclassified to Aridic subgoup if allowed for frigid temperature regime. (7/96-CJH)