LOCATION WEEDZUNIT MTEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Typic Haplustolls
TYPICAL PEDON: Weedzunit loam, in rangeland (colors are for dry soil unless otherwise noted).
A1--0 to 7 inches; grayish brown (10YR 5/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; many fine and very fine interstitial pores; slightly acid (pH 6.2); clear smooth boundary.
A2--7 to 11 inches; grayish brown (10YR 5/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to weak fine and medium granular; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; many fine and very fine pores; slightly acid (pH 6.2); clear smooth boundary. (Combined thickness of A horizon is 7 to 15 inches.)
Bw1--11 to 17 inches; grayish brown (10YR 5/2) fine sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots; many fine and very fine pores; 5 percent pebbles; slightly acid (pH 6.4); clear smooth boundary.
Bw2--17 to 24 inches; brown (10YR 5/3) fine sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common fine and medium roots; many fine and very fine pores; 10 percent pebbles; slightly acid (pH 6.4); gradual smooth boundary. (Combined thickness of the Bw horizons is 11 to 21 inches)
BC--24 to 29 inches; light brownish gray (10YR 6/2) gravelly fine sandy loam, grayish brown (10YR 5/2) moist; weak coarse prismatic structure; soft, very friable, nonsticky and nonplastic; few fine and medium roots; common fine and very fine pores; 25 percent pebbles; neutral (pH 6.6); gradual smooth boundary. (0 to 8 inches thick)
R--29 inches; volcanic mudflow breccia.
TYPE LOCATION: Sweet Grass County, Montana; 500 feet west and 300 feet south of the northeast corner of section 8, T.2 S., R.15 E.; Latitude - 45 degrees, 40 minutes, 49 seconds North; Longitude - 109 degrees, 53 minutes, 44 seconds West.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches, moist in some or all parts from April through mid July, dry in some part less than six-tenths of the cumulative days per year when the soil temperature at a depth of 20 inches is 41 degrees or higher.
Mollic epipedon thickness - 7 to 15 inches.
Rock fragments - angular pebbles of lahar breccia.
Depth to bedrock - 20 to 40 inches.
A horizons - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: loam or fine sandy loam
Clay content: 10 to 18 percent
Rock fragments: 0 to 15 percent pebbles
Reaction: pH 5.6 to 7.3
Bw1 horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: loam or fine sandy loam
Clay content: 10 to 18 percent
Rock fragments: 0 to 15 percent pebbles
Reaction: pH 5.6 to 7.3
Bw2 horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: loam or fine sandy loam
Clay content: 10 to 18 percent
Rock fragments: 0 to 15 percent pebbles
Reaction: pH 5.6 to 7.3
BC horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: loam, fine sandy loam or sandy loam
Clay content: 10 to 18 percent
Rock fragments: 15 to 60 percent pebbles
Reaction: pH 5.6 to 7.3
COMPETING SERIES:
Baggs (MT) - does not have a lithic contact above a depth of 60 inches.
Baxton (MT) - paralithic contact at 20 to 40 inches; lithic contact at 40 to 60 inches.
Belain (MT) - has a horizon of secondary calcium carbonate accumulation.
Bitterroot (MT) - Paralithic contact at depths of 20 to 40 inches
Chincap (WY) - does not have a Bw horizon; formed in sandstone residuum.
Hopley (MT) - has horizon of secondary carbonate accumulation.
Mott (ND) - does not have a lithic contact above a depth of 60 inches.
Relan (MT) - does not have a lithic contact above a depth of 60 inches; has a horizon of secondary calcium carbonate accumulation.
Tally (MT) - does not have a lithic contact above a depth of 60 inches; has a horizon of secondary calcium carbonate accumulation.
Unaweep (CO) - does not have a lithic contact above a depth of 60 inches; has a horizon of secondary calcium carbonate accumulation.
Vebar (ND) - paralithic contact at depths of 20 to 40 inches; has a horizon of secondary calcium carbonate accumulation.
Victor (MT) - does not have a lithic contact above a depth of 60 inches; is sandy skeletal at a moderate depth.
GEOGRAPHIC SETTING:
Landform - hills, escarpments and lahars.
Elevation - 3,900 to 6,200 feet.
Parent material - residuum and colluvium from volcanic mudflow breccia.
Slope - 0 to 35 percent.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 20 inches, most of which falls during spring and early summer.
Mean annual air temperature - 39 to 45 degrees F.
Frost-free period - 70 to 120 days.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability.
USE AND VEGETATION: Weedzunit soils are used mainly for rangeland. Potential native vegetation is mainly Idaho fescue, Columbia needlegrass, prairie junegrass, bluebunch wheatgrass, and fringed sagewort.
DISTRIBUTION AND EXTENT: Weedzunit soils are of moderate extent in South Central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sweet Grass County Area, Montana, 2000.
REMARKS: Soil Interpretations Record: MT1424. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 11 inches (A1 and A2 horizons); a cambic horizon from 11 to 24 inches (Bw1 and Bw2 horizons); a lithic contact at 29 inches (R horizon). A particle-size control section from 10 to 29 inches (A2, Bw1, Bw2 and BC horizons). Weedzunit soils have a frigid temperature regime and an ustic moisture regime.
ADDITIONAL DATA: NSSL: Pedon 95P 120, Samples 95P825-829