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

110 Soil Survey
Cgk3—49 to 60 inches; grayish brown (2.5Y 5/2)
cobbly clay loam, dark grayish brown (2.5Y 4/2)
moist; common fine distinct olive (5Y 5/6) moist,
redox concentrations; massive; moderately hard,
friable, moderately sticky, moderately plastic;
common carbonate coats on rock fragments,
common fine and medium masses of lime;
10 percent gravel; 15 percent cobbles; strongly
effervescent; slightly alkaline (pH 7.4).
Range in Characteristics
Soil temperature: 38 to 45 degrees F
Moisture control section: Between 4 and 12 inches
Thickness of the mollic epipedon: 20 to 40 inches
Depth to the seasonal high water table: 6 to
24 inches
Note: Some pedons have a 2Cg horizon below a
depth of 40 inches.
A1 horizon
Hue: 10YR, 2.5Y, 5Y, or N
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 0 to 2
Texture (less than 2 mm): Loam
Clay content: 18 to 27 percent
Content of rock fragments: 0 to 35 percent—0 to
10 percent stones and cobbles; 0 to 25 percent
gravel
Calcium carbonate equivalent: 1 to 15 percent
Reaction: pH 6.6 to 8.4
A2, A3, and A4 horizons
Hue: 10YR, 2.5Y, 5Y, or N
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 0 to 2
Redox concentrations: Few to many; chroma of 4
or 6
Texture (less than 2 mm): Loam, clay loam, or silt
loam
Clay content: 18 to 35 percent
Content of rock fragments: 0 to 35 percent—0 to
10 percent stones and cobbles; 0 to 25 percent
gravel
Calcium carbonate equivalent: 1 to 15 percent
Reaction: pH 6.6 to 8.4
Cgk horizons
Hue: N, 10YR, 2.5Y, or 5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 0 to 2
Redox concentrations: None to many; chroma of
4 or 6
Texture (less than 2 mm): Clay loam, silt loam, or
loam
Clay content: 18 to 35 percent
Content of rock fragments: 5 to 35 percent—0 to
15 percent stones and cobbles; 5 to 20 percent
gravel
Calcium carbonate equivalent: 1 to 15 percent
Reaction: pH 7.4 to 8.4
Overfelt Series
Depth class: Very deep (greater than 60 inches)
Drainage class: Well drained
Permeability: In the upper 0 to 27 inches = very slow
(less than 0.6 inch/hour)
Landform: Fan, stream terrace, and terrace
Parent material: Clayey over gravelly alluvium
Slope range: 0 to 4 percent
Elevation range: 4,200 to 6,000 feet
Mean annual precipitation: 15 to 19 inches
Mean annual air temperature: 43 to 45 degrees F
Frost-free period: 85 to 115 days
Taxonomic Class: Clayey over loamy-skeletal,
smectitic over mixed, superactive, frigid Vertic
Argiustolls
Typical Pedon
Overfelt clay loam, in an area of Overfelt-Roy
complex, 0 to 4 percent slopes, in an area of pasture,
2,000 feet north and 2,400 feet east of the southwest
corner of sec. 8, T. 1 S., R. 16 E.; USGS Greycliff
topographic quadrangle (lat. 45 o 45'33" N.; long.
109 o 46'41" W.)
A—0 to 8 inches; brown (7.5YR 4/2) clay loam, dark
brown (7.5YR 3/2) moist; weak fine subangular
blocky structure parting to moderate fine
granular; slightly hard, friable, slightly sticky,
slightly plastic; few medium and common fine
roots; many very fine and fine pores; 2 percent
gravel; 3 percent cobbles; neutral (pH 7.0); abrupt
smooth boundary.
Bt1—8 to 16 inches; brown (7.5YR 5/2) clay, dark
brown (7.5YR 4/2) moist; moderate medium
prismatic structure parting to strong medium
subangular blocky; very hard, firm, very sticky,
very plastic; common fine roots; common very
fine and fine pores; common pressure faces and
cracks 1 /4- to 1 /2-inch wide; many distinct
continuous grayish brown (10YR 5/2) moist; clay
films on faces of peds and lining pores; 5 percent
gravel; neutral (pH 7.2); clear smooth boundary.
Bt2—16 to 27 inches; brown (7.5YR 5/2) clay, dark
brown (7.5YR 4/2) moist; moderate medium
prismatic structure parting to strong medium