LOCATION REGULUS MT
Established Series
REV. KTS-RJS
01/2012
REGULUS SERIES
The Regulus series consists of very deep, poorly drained soils that formed in alluvium derived from mixed sources. These soils occur on flood plains. Slopes are 0 to 2 percent. Mean annual precipitation is about 430 mm, and the mean annual temperature is about 3 degrees C.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Cumulic Cryaquolls
TYPICAL PEDON: Regulus silt loam, in pastureland, on a 1 percent slope at an elevation of 1895 meters (Colors are for moist soil unless otherwise noted).
Oi--0 to 5 cm; undecomposed and partially decomposed matted roots; abrupt smooth boundary. (0 to 6 cm)
A1--5 to 25 cm; very dark brown (10YR 2/2) silt loam, very dark grayish brown (10YR 3/2) dry; moderate medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine, and few medium and coarse roots; many very fine and fine irregular pores; neutral (pH 6.8); clear smooth boundary.
A2--25 to 35 cm; very dark grayish brown (10YR 3/2)gravelly sandy loam, dark grayish brown (10YR 4/2) dry; weak medium subangular blocky structure parting to moderate medium granular; soft, very friable, nonsticky and nonplastic; many very fine and common fine roots; many very fine and fine irregular pores; 18 percent gravel; neutral (pH 6.6); clear wavy boundary. (combined thickness of A horizons - 25 to 45 cm)
Bg--35 to 79 cm; black (10YR 2/1) clay loam, gray (10YR 5/1) dry; 10 percent fine and medium, prominent, irregular, strong brown (7.5YR 4/6) redox concentrations; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; 5 percent gravel; slightly acid (pH 6.4); clear wavy boundary. (30 to 50 cm thick)
Cg1--79 to 117 cm; dark grayish brown (10YR 4/2) gravelly sandy loam, light brownish gray (10YR 6/2) dry; 15 percent fine and medium, prominent, irregular, strong brown (7.5YR 4/6) redox concentrations; massive; soft, very friable, nonsticky and nonplastic; few very fine and fine roots; 20 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (25 to 50 cm thick)
Cg2--117 to 152 cm; variegated, extremely gravelly loamy coarse sand; single grain; loose, nonsticky and nonplastic; 70 percent gravel; slightly acid (pH 6.4).
TYPE LOCATION: Beaverhead County, Montana; located about 198 meters north and 350 meters east of the southwest corner of sec. 7, T. 6 S., R 12 W; Tash Peak topographic quadrangle; UTM 12T, 0333384e., 5021233n. NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 1 to 4 degrees C.
Thickness of mollic epipedon - 50 to 80 cm
Depth to sandy-skeletal material - 100 to 150 cm
Depth to redoximorphic features - 30 to 60 cm
Particle-size control section - averages 18 to 30 percent clay
A1, A2 horizons
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2; dry or moist
Texture: silt loam or sandy loam
Clay content: 15 to 26 percent
Rock fragments: 0 to 35 percent--0 to 30 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.0 to 7.3
Bg horizon
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 1 or 2; dry or moist
Texture: loam, clay loam or silty clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 35 percent--0 to 30 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.0 to 7.3
Cg1 horizon
Value: 4 to 6 dry; 3 or 4 moist
Chroma: 1 or 2; dry or moist
Texture: sandy loam or loam
Clay content: 15 to 26 percent
Rock fragments: 0 to 35 percent--0 to 30 percent gravel, 0 to 5 percent cobbles
Reaction: pH 6.0 to 7.3
Cg2 horizon
Texture: loamy coarse sand, loamy sand, coarse sand or sand
Clay content: 1 to 10 percent
Rock fragments: 35 to 75 percent--35 to 75 percent gravel, 0 to 10 percent cobbles
Reaction: pH 6.0 to 7.3
COMPETING SERIES:
Almont (CO) - have flagstones in the control section
Venable (CO) - have an ACg horizon
Wiskisprings (ID) - have a lithologic discontinuity
GEOGRAPHIC SETTING:
Landform - flood plains
Elevation - 1830 to 2250 meters
Slope - 0 to 2 percent
Parent material - alluvium derived from mixed sources
Climate - long, cold winters; moist springs; short warm summers
Mean annual precipitation - 380 to 480 mm
Mean annual air temperature - 1 to 4 degrees C.
Frost-free period - 50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Poorly drained; moderate over rapid permeability.
USE AND VEGETATION: Regulus soils are used mainly for wildlife and pasture. The vegetation is mainly willows, sedges, rushes, and miscellaneous grasses and forbs.
DISTRIBUTION AND EXTENT: Regulus soils are of small extent in southwestern Montana. MLRAs - 43B, 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Horse Prairie-South Valley Area - Part of Beaverhead County, Montana, 2011; proposed in Beaverhead County, Montana, 2011.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 5 to 79 cm (A1, A2 and Bg horizons)
Particle-size control section - from 30 to 105 cm (part of A2, Bg and Cg1 horizons)
Regulus soils have a cryic temperature regime and an aquic moisture regime.
National Cooperative Soil Survey
U.S.A.