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

Sweet Grass County Area, Montana—Part I 47
Parent material: Loamy residuum weathered from
sandstone and siltstone
Slope range: 2 to 60 percent
Elevation range: 3,750 to 5,200 feet
Mean annual precipitation: 10 to 14 inches
Mean annual air temperature: 43 to 46 degrees F
Frost-free period: 95 to 125 days
Taxonomic Class: Loamy, mixed, superactive,
calcareous, frigid, shallow Aridic Ustorthents
Typical Pedon
Cabbart loam, in an area of grassland, 1,200 feet
north and 2,450 feet east of the southwest corner of
sec. 7, T. 20 N., R. 3 W.; Cascade County, Montana.
A—0 to 3 inches; light brownish gray (2.5Y 6/2) loam,
dark grayish brown (2.5Y 4/2) moist; weak fine
granular structure; slightly hard, very friable,
slightly sticky, slightly plastic; many fine roots and
pores; strongly effervescent; moderately alkaline
(pH 8.4); clear wavy boundary.
Bk1—3 to 7 inches; light brownish gray (2.5Y 6/2)
loam, grayish brown (2.5Y 5/2) moist; weak
medium prismatic structure; hard, very friable,
slightly sticky, slightly plastic; many fine roots and
pores; few fine masses of lime; strongly
effervescent; moderately alkaline (pH 8.4); clear
wavy boundary.
Bk2—7 to 16 inches; pale yellow (2.5Y 7/4) loam,
light yellowish brown (2.5Y 6/4) moist; weak
coarse prismatic structure; hard, very friable,
slightly sticky, slightly plastic; many fine roots and
pores; common fine masses of lime; strongly
effervescent; moderately alkaline (8.4); clear
wavy boundary.
BC—16 to 18 inches; pale yellow (2.5Y 7/4) loam,
light yellowish brown (2.5Y 6/4) moist; weak
coarse prismatic structure; very hard, friable,
slightly sticky, slightly plastic; many fine roots and
pores; disseminated lime; strongly effervescent;
moderately alkaline (pH 8.4); clear wavy
boundary.
Cr—18 to 60 inches; pale yellow (5Y 7/4)
semiconsolidated loamy sedimentary beds that
crush to loam; few widely spaced vertical cracks
in upper 4 to 6 inches with roots; root mat at
contact of beds.
Range in Characteristics
Soil temperature: 42 to 47 degrees F
Moisture control section: Between 4 and 12 inches
Depth to the Cr horizon: 10 to 20 inches
Note: Some pedons do not have a BC horizon.
A horizon
Hue: 10YR, 2.5Y, or 5Y
Value: 5 to 7 dry; 3 to 5 moist
Chroma: 2 or 3
Texture (less than 2 mm): Loam
Clay content: 18 to 27 percent
Content of rock fragments: 0 to 60 percent—0 to
20 percent cobbles; 0 to 40 percent gravel
Calcium carbonate equivalent: 5 to 10 percent
Reaction: pH 7.4 to 9.0
Bk horizons
Hue: 10YR, 2.5Y, or 5Y
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 4
Texture (less than 2 mm): Loam, clay loam, silt
loam, or silty clay loam
Clay content: 18 to 35 percent
Content of rock fragments: 0 to 45 percent—0 to
15 percent hard gravel; 0 to 45 percent soft
gravel
Calcium carbonate equivalent: 10 to 25 percent
Reaction: pH 7.4 to 9.0
BC horizon
Hue: 10YR, 2.5Y, or 5Y
Value: 5 to 8 dry; 4 to 6 moist
Chroma: 2 to 4
Texture (less than 2 mm): Loam, clay loam, silt
loam, or silty clay loam
Clay content: 18 to 35 percent
Content of rock fragments: 0 to 45 percent—0 to
15 percent hard gravel; 0 to 45 percent soft
gravel
Calcium carbonate equivalent: 5 to 25 percent
Reaction: pH 7.4 to 9.0
Cambeth Series
Depth class: Moderately deep (20 to 40 inches)
Drainage class: Well drained
Permeability: Moderate (0.6 to 2.0 inches/hour)
Landform: Hill
Parent material: Silty residuum weathered from
sandstone and siltstone
Slope range: 4 to 15 percent
Elevation range: 3,750 to 5,200 feet
Mean annual precipitation: 10 to 14 inches
Mean annual air temperature: 40 to 45 degrees F
Frost-free period: 95 to 125 days
Taxonomic Class: Fine-silty, mixed, superactive,
frigid Aridic Calciustepts