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

94 Soil Survey
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; the
upper 7 inches, when mixed, meet the
requirements of a mollic epipedon.
Depth to the seasonal high water table: 24 to
60 inches
Depth to the Bk horizon: 12 to 24 inches
Depth to the 3C horizon: 36 to 50 inches
Az horizon
Hue: 10YR, 2.5Y, or 5Y
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 1 or 2
Texture (less than 2 mm): Clay loam or loam
Clay content: 15 to 35 percent
Content of rock fragments: 0 to 35 percent—0 to
5 percent cobbles; 0 to 30 percent gravel
Electrical conductivity: 4 to 8 mmhos/cm
Sodium adsorption ratio: 0 to 20
Reaction: pH 6.6 to 8.4
Bz horizons
Hue: 10YR, 2.5Y, or 5Y
Value: 4 to 7 dry; 4 to 6 moist
Chroma: 1 to 3
Texture (less than 2 mm): Loam or clay loam
Clay content: 18 to 35 percent
Content of rock fragments: 0 to 15 percent gravel
Electrical conductivity: 2 to 8 mmhos/cm
Sodium adsorption ratio: 0 to 25
Calcium carbonate equivalent: 3 to 12 percent
Reaction: pH 7.4 to 8.4
Bkgz horizon
Hue: 10YR, 2.5Y, or 5Y
Value: 4 to 7 dry; 4 to 6 moist
Chroma: 1 to 3
Texture (less than 2 mm): Loam or clay loam
Clay content: 18 to 35 percent
Content of rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 3 to 12 percent
Electrical conductivity: 2 to 8 mmhos/cm
Sodium adsorption ratio: 0 to 25
Reaction: pH 7.4 to 8.4
2Cg horizon
Hue: 10YR, 2.5Y, or 5Y
Value: 4 to 7 dry; 4 to 6 moist
Chroma: 1 to 3
Texture (less than 2 mm): Sandy loam, fine sandy
loam, or loam
Clay content: 10 to 27 percent
Content of rock fragments: 10 to 35 percent
gravel
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: 4 to 8 mmhos/cm
Sodium adsorption ratio: 0 to 30
Reaction: pH 7.4 to 9.0
3Cg horizon
Hue: 10YR, 2.5Y, or 5Y
Value: 4 to 7 dry; 4 to 6 moist
Chroma: 1 to 3
Texture (less than 2 mm): Loamy sand, loamy
coarse sand, or sand
Clay content: 10 to 15 percent
Content of rock fragments: 35 to 60 percent—0 to
10 percent cobbles; 0 to 60 percent gravel
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: 2 to 8 mmhos/cm
Sodium adsorption ratio: 0 to 20
Reaction: pH 7.4 to 9.0
Marmarth Series
Depth class: Moderately deep (20 to 40 inches)
Drainage class: Well drained
Permeability: Moderate (0.6 to 2.0 inches/hour)
Landform: Hill, terrace, and swale on plain
Parent material: Loamy residuum weathered from
sandstone and siltstone
Slope range: 2 to 15 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: Fine-loamy, mixed, superactive,
frigid Aridic Argiustolls
Typical Pedon
Marmarth loam, in an area of Marmarth loam, 2 to
8 percent slopes, in an area of rangeland, 1,200 feet
south and 400 feet east of the northwest corner of
sec. 11, T. 3 N., R. 17 E.; USGS Gibson topographic
quadrangle (lat. 46 o 01'42" N.; long. 109 o 35'16" W.)
A—0 to 5 inches; grayish brown (10YR 5/2) loam,
very dark grayish brown (10YR 3/2) moist; weak
fine granular structure; soft, very friable, slightly
sticky, slightly plastic; many very fine and fine
roots; many very fine and fine pores; neutral
(pH 6.7); clear smooth boundary.
Bt1—5 to 9 inches; brown (10YR 4/3) loam, dark
brown (10YR 3/3) moist; weak fine and medium
subangular blocky structure; slightly hard, very
friable, slightly sticky, slightly plastic; many very
fine and fine roots; many very fine pores;
common faint discontinuous dark yellowish brown