Soil Survey of Sweet Grass County Area, Montana - Soil Data Mart

118 Soil Survey
Reedwest Series
Depth class: Moderately deep (20 to 40 inches)
Drainage class: Well drained
Permeability: Moderate (0.6 to 2.0 inches/hour)
Landform: Escarpment, hill, terrace, and swale on
plain
Parent material: Loamy residuum weathered from
sandstone and siltstone
Slope range: 0 to 60 percent
Elevation range: 3,900 to 6,200 feet
Mean annual precipitation: 15 to 20 inches
Mean annual air temperature: 39 to 45 degrees F
Frost-free period: 70 to 115 days
Taxonomic Class: Fine-loamy, mixed, superactive,
frigid Typic Argiustolls
Typical Pedon
Reedwest loam, in an area of Reedwest-Castner
complex, 2 to 8 percent slopes, in an area of
rangeland, 200 feet south and 1,300 feet east of
the northwest corner of sec. 33, T. 5 N., R. 15 E.;
USGS Gougley Creek topographic quadrangle
(lat. 46 o 08'48" N.; long. 109 o 51'25" W.)
A—0 to 6 inches; dark grayish brown (10YR 4/2)
loam, very dark grayish brown (10YR 3/2) moist;
moderate fine subangular blocky structure
parting to weak fine and medium granular; soft,
very friable, slightly sticky, nonplastic; few
medium and common very fine and fine roots;
many very fine and fine pores; slightly alkaline
(pH 7.6); abrupt smooth boundary.
Bt1—6 to 13 inches; dark grayish brown (10YR 4/2)
loam, very dark grayish brown (10YR 3/2) moist;
moderate fine prismatic structure; slightly hard,
friable, slightly sticky, slightly plastic; common
very fine and fine roots; common very fine and
fine pores; common faint discontinuous dark
brown (10YR 3/3) moist; clay films on faces of
peds and lining pores; slightly alkaline (pH 7.6);
clear smooth boundary.
Bt2—13 to 19 inches; brown (10YR 5/3) clay loam,
dark brown (10YR 4/3) moist; moderate medium
prismatic structure parting to strong medium
subangular blocky; slightly hard, friable,
moderately sticky, moderately plastic; few very
fine and fine roots; common very fine and fine
pores; common distinct discontinuous dark brown
(10YR 3/3) moist; clay films on faces of peds and
lining pores; slightly alkaline (pH 7.6); clear
smooth boundary.
Bk—19 to 27 inches; light brownish gray (2.5Y 6/2)
loam, grayish brown (2.5Y 4/2) moist; moderate
medium subangular blocky structure; slightly
hard, very friable, slightly sticky, slightly plastic;
common very fine and fine pores; common
medium soft masses of lime; strongly
effervescent; moderately alkaline (pH 8.4); abrupt
smooth boundary.
Cr—27 to 60 inches; calcareous soft sandstone.
Range in Characteristics
Soil temperature: 41 to 47 degrees F
Moisture control section: Between 4 and 12 inches
Thickness of the mollic epipedon: 7 to 15 inches
Depth to the Bk horizon: 11 to 30 inches
Depth to bedrock: 20 to 40 inches
A horizon
Hue: 10YR or 2.5Y
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture (less than 2 mm): Loam
Clay content: 15 to 27 percent
Content of rock fragments: 0 to 15 percent gravel
Reaction: pH 6.1 to 7.8
Bt horizons
Hue: 10YR or 2.5Y
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 4
Texture (less than 2 mm): Loam, sandy clay loam,
or clay loam
Clay content: 18 to 35 percent
Content of rock fragments: 0 to 15 percent gravel
Reaction: pH 6.6 to 7.8
Bk horizon
Hue: 10YR, 2.5Y, or 5Y
Value: 6 to 8 dry; 4 to 6 moist
Chroma: 2 to 4
Texture (less than 2 mm): Loam, sandy clay loam,
fine sandy loam, or clay loam
Clay content: 15 to 30 percent
Content of rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 8.4
Rentsac Series
Depth class: Shallow (10 to 20 inches)
Drainage class: Well drained
Permeability: Moderate (0.6 to 2.0 inches/hour)
Landform: Escarpment, hill, and knoll on plain
Parent material: Residuum weathered from
calcareous sandstone
Slope range: 2 to 60 percent
Elevation range: 3,750 to 5,200 feet