LOCATION RAGHORN MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Haplustalfs
TYPICAL PEDON: Raghorn sandy loam, in rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 3 inches; grayish brown (10YR 5/2) sandy loam, dark brown (10YR 3/3) moist; moderate medium granular structure; slightly hard, friable, slightly sticky and nonplastic; many very fine and fine roots; slightly alkaline (pH 7.6); clear smooth boundary. (3 to 5 inches thick)
A2--3 to 7 inches; brown (10YR 5/3) sandy loam, dark yellowish brown (10YR 3/4) moist; moderate coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine and fine and few medium roots; slightly alkaline (pH 7.8); clear smooth boundary. (3 to 5 inches thick)
Bt--7 to 12 inches; brown (10YR 5/3) sandy clay loam, dark yellowish brown (10YR 3/4) moist; strong coarse prismatic structure parting to strong medium and coarse angular blocky; hard, firm, moderately sticky and moderately plastic; many very fine and fine roots; common fine and very fine tubular pores; common distinct brown (10YR 4/3 clay films on faces of peds; slightly alkaline (pH 7.6); gradual smooth boundary. (5 to 13 inches thick)
BC--12 to 20 inches; pale brown (10YR 6/3) sandy loam, dark yellowish brown (10YR 4/4) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, nonsticky and nonplastic; many very fine and fine roots; slightly alkaline (pH 7.6); gradual smooth boundary. (7 to 15 inches thick)
2C--20 to 44 inches; pale brown (10YR 6/3) loamy coarse sand, yellowish brown (10YR 5/4) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; disseminated lime; slightly effervescent; slightly alkaline (pH 7.6).
3C--44 to 60 inches; pale brown (10YR 6/3) stratified sandy loam and loam, dark yellowish brown (10YR 4/4) moist; massive; soft, very friable, slightly sticky and slightly plastic; slightly alkaline (pH 7.8).
TYPE LOCATION: Jefferson County, Montana; 870 feet north and 1,280 feet east of the SW corner of sec. 26, T. 2 N., R. 5 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 46 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 41 degrees F and higher.
Depth to argillic horizon - 6 to 11 inches.
Surface boulders - 0 to 1 percent.
A horizons - Chroma: 3 or 4
Clay content: 10 to 20 percent
Rock fragments: 0 to 25 percent--0 to 15 percent pebbles, 0 to 10 percent cobbles
Reaction: pH 6.6 to 7.8
Bt horizon - Chroma: 3 or 4
Texture: sandy loam or sandy clay loam
Clay content: 18 to 25 percent
Rock fragments: 0 to 15 percent--0 to 15 percent pebbles, 0 to 3 percent cobbles
Reaction: pH 6.6 to 7.8
BC horizon - Chroma: 3 or 4
Texture: fine sandy loam, sandy loam or coarse sandy loam
Clay content: 5 to 15 percent
Reaction: pH 7.4 to 8.4
C horizons - Chroma: 3 or 4
Texture: loamy coarse sand or stratified sandy loam and loam
Clay content: 5 to 18 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Bondoe (MT) - has a horizon of secondary carbonate accumulation.
Ferball (MT) - has horizon of secondary carbonate accumulation.
GEOGRAPHIC SETTING:
Landform - alluvial fans; stream terraces; hills.
Elevation - 3,800 to 5,000 feet.
Slope- 0 to 70 percent.
Parent material - alluvium derived from granite.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual air temperature - 40 to 44 degrees F.
Frost-free period - 90 to 115 days.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Raghorn soils are mainly used for rangeland and cropland. The potential native vegetation is mainly bluebunch wheatgrass, needleandthread, western wheatgrass, blue gramma, fringed sagewort, salsify, rubber rabbitbrush, and big sagebrush.
DISTRIBUTION AND EXTENT: Raghorn soils are of small extent
in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Jefferson County, Montana, 1998.
REMARKS: Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (A horizons); an argillic horizon from 7 to 12 inches (Bt horizon); a particle-size control section from 7 to 12 inches (Bt horizon); a lithologic discontinuity at 20 to 60 inches(2C and 3C horizons). Raghorn soils have a frigid temperature regime and an ustic moisture regime boarding on aridic.