LOCATION BROADUS MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Haplustepts
TYPICAL PEDON: Broadus loam, forested (colors are for dry soil unless otherwise noted).
Oi--1 inch to 0; slightly decomposed forest litter. (1/2 to 4 inches thick)
A--0 to 4 inches; light yellowish brown (10YR 6/4) loam, grayish brown (10YR 5/2) moist; weak fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine roots; many fine tubular pores; neutral (pH 6.6); clear smooth boundary. (2 to 8 inches thick)
Bw--4 to 12 inches; pale brown (10YR 6/3) loam, grayish brown (10YR 5/2) moist; moderate medium prismatic structure parting to strong medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many fine tubular pores; slightly effervescent; slightly alkaline (pH 7.5); clear smooth boundary. (8 to 12 inches thick)
Bk1--12 to 18 inches; light brownish gray (2.5Y 6/2) loam, grayish brown (2.5Y 5/2) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many fine tubular pores; many fine masses of lime; violently effervescent; slightly alkaline (pH 7.7); gradual smooth boundary. (7 to 18 inches thick)
Bk2--18 to 34 inches; light brownish gray (2.5Y 6/2) silty clay loam, grayish brown (2.5Y 5/2) moist; weak coarse prismatic structure; slightly hard, friable, sticky and plastic; many fine and medium roots; many fine tubular pores; many medium and coarse masses of lime; violently effervescent; moderately alkaline (pH 7.9); gradual smooth boundary. (12 to 20 inches thick)
Bk3--34 to 60 inches; light gray (2.5Y 7/2) silt loam, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure; slightly hard, friable, sticky and plastic; many fine roots; many fine tubular pores; many medium and coarse masses of lime; violently effervescent; moderately alkaline (pH 7.9).
TYPE LOCATION: Carter County, Montana; 1,500 feet north and 300 feet east of the SW corner of sec. 5, T. 8 S., R. 55 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 47 degrees F.
Moisture control section - between 4 to 12 inches; frozen between approximately October 15 through April 15.
Depth to Bk horizon - 11 to 15 inches.
The surface 7 inches when mixed does not meet the requirements for a mollic epipedon
A horizon - Hue: 10YR or 5Y
Value: 4, 5, or 6 dry; 3, 4, or 5 moist
Chroma: 2, 3, or 4
Texture: loam or clay loam
Clay content: 18 to 35 percent
Reaction: pH 6.6 to 7.8
Bw horizon - Hue: 10YR or 5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: loam, clay loam, or silty clay loam
Clay content: 18 to 35 percent
Sand content: 15 to 35 percent fine and medium sand
Reaction: pH 6.6 to 7.8
Bk1 horizon - Hue: 10YR, 2.5Y or 5Y
Value: 6 or 7 dry; 4, 5 or 6 moist
Chroma: 2, 3 or 4
Texture: loam, clay loam, or silty clay loam
Clay content: 18 to 35 percent
Sand content: 15 to 35 percent fine and medium sand
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
Bk2 and Bk3 horizon - Hue: 10YR, 2.5Y or 5Y
Value: 6 or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3 or 4
Texture: loam, silt loam, fine sandy loam, clay loam, or silty clay loam
Clay content: 18 to 35 percent
Sand content: 15 to 35 percent fine and medium sand
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES:
Arikara (ND) - is noncalcareous in the cambic horizon.
Doney (MT) - calcareous throughout, Cr horizon at depth of 20 to 40 inches.
Eaglewing (MT) - calcic horizon, formed in till.
Macar (MT) - more than 35 percent fine and coarser sand in the control section.
Mara (NM) - moist in some part of the moisture control section, dry in May and June, strongly effervescent throughout.
Slategoat (MT) - base of cambic horizon deeper than 15 inches, AB horizon, and 70 to 80 day frost-free season.
GEOGRAPHIC SETTING:
Landform - alluvial fans and hills.
Elevation - 2,900 to 4,500 feet.
Slope- 8 to 65 percent.
Parent material - alluvium or colluvium derived from semiconsolidated loamy sedimentary beds.
Climate - cool with long, cold, dry winters; moist springs; and warm summers.
Mean annual precipitation - 12 to 19 inches.
Mean annual air temperature - 39 to 45 degrees F.
Frost-free period - 110 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: The Broadus soils are used mainly for grazeable woodland. The potential native vegetation is mainly ponderosa pine with an understory of green needlegrass and western wheatgrass.
DISTRIBUTION AND EXTENT: The Broadus series is on sedimentary plains of eastern Montana. The series is of limited extent. Broadus is a place name.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Custer County, Montana, 1995; Series proposed Carter County, Montana, 1980.
REMARKS: Soil interpretations record: MT0592. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (mixed)(A and part of Bw horizons); a cambic horizon from 4 to 12 inches (Bw horizon); secondary carbonate accumulation from 12 to 60 inches (Bk1, Bk2, Bk3 horizons); a particle-size control section from 10 to 40 inches (Bw, Bk1, Bk2, and part of Bk3 horizons). The Broadus series has a frigid temperature regime and an ustic moisture regime.