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

Sweet Grass County Area, Montana—Part I 125
Content of rock fragments: 0 to 5 percent gravel
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: 0 to 4 mmhos/cm
Reaction: pH 7.4 to 8.4
Sawicki Series
Depth class: Very deep (greater than 60 inches)
Drainage class: Well drained
Permeability: Moderate (0.6 to 2.0 inches/hour)
Landform: Hill
Parent material: Gravelly alluvium, gravelly colluvium
or gravelly till
Slope range: 4 to 25 percent
Elevation range: 5,300 to 6,200 feet
Mean annual precipitation: 17 to 20 inches
Mean annual air temperature: 39 to 43 degrees F
Frost-free period: 70 to 90 days
Taxonomic Class: Loamy-skeletal, mixed,
superactive, frigid Typic Argiustolls
Typical Pedon
Sawicki very gravelly loam, in an area of Sawicki,
extremely bouldery-Bowery complex, 4 to 25 percent
slopes, in an area of rangeland, 900 feet south and
1,000 feet east of the northwest corner of sec. 35,
T. 2 S., R. 12 E.; USGS McLeod Basin topographic
quadrangle (lat. 45 o 37'21" N.; long. 110 o 12'48" W.)
A—0 to 8 inches; very dark grayish brown (10YR 3/2)
very gravelly loam, very dark brown (10YR 2/2)
moist; moderate very fine and fine granular
structure; soft, very friable, nonsticky, nonplastic;
few medium and many very fine and fine roots;
many very fine and fine pores; 25 percent gravel;
10 percent cobbles; 5 percent stones; slightly
acid (pH 6.4); clear smooth boundary.
Bt1—8 to 15 inches; brown (10YR 4/3) very cobbly
clay loam, very dark grayish brown (10YR 3/2)
moist; moderate fine and medium subangular
blocky structure; slightly hard, firm, slightly sticky,
slightly plastic; few medium and common very
fine and fine roots; common very fine and fine
pores; common distinct discontinuous dark
yellowish brown (10YR 3/4) moist; clay films on
faces of peds; 20 percent gravel; 17 percent
cobbles; 3 percent stones; neutral (pH 6.8); clear
smooth boundary.
Bt2—15 to 29 inches; brown (10YR 5/3) very cobbly
sandy clay loam, brown (10YR 4/3) moist; weak
fine and medium subangular blocky structure;
slightly hard, friable, slightly sticky, slightly plastic;
few very fine to medium roots; few very fine
pores; faint patchy dark yellowish brown (10YR
3/4) moist; clay films on faces of peds; 27 percent
gravel; 23 percent cobbles; 7 percent stones;
neutral (pH 6.8); clear smooth boundary.
C—29 to 60 inches; light olive brown (2.5Y 5/4)
extremely cobbly loam, olive brown (2.5Y 4/4)
moist; massive; soft, very friable, nonsticky,
nonplastic; few very fine and fine roots;
30 percent gravel; 30 percent subrounded
cobbles; 7 percent stones; neutral (pH 6.8).
Range in Characteristics
Soil temperature: 40 to 45 degrees F
Moisture control section: Between 4 and 12 inches
Thickness of the mollic epipedon: 7 to 16 inches
Note: Some pedons have a BC horizon.
A horizon
Hue: 10YR or 2.5Y
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 2 or 3
Texture (less than 2 mm): Loam
Clay content: 12 to 27 percent
Content of rock fragments: 10 to 50 percent—0 to
5 percent boulders; 5 to 20 percent stones and
cobbles; 5 to 30 percent gravel
Reaction: pH 6.6 to 7.3
Bt1 horizon
Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 to 4
Texture (less than 2 mm): Clay loam, sandy clay
loam, or loam
Clay content: 20 to 30 percent
Content of rock fragments: 15 to 60 percent—
10 to 35 percent stones and cobbles; 5 to
40 percent gravel
Reaction: pH 6.6 to 7.8
Bt2 horizon
Hue: 10YR or 2.5Y
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 4
Texture (less than 2 mm): Sandy clay loam,
sandy loam, or loam
Clay content: 15 to 25 percent
Content of rock fragments: 35 to 60 percent—
15 to 45 percent stones and cobbles; 20 to
40 percent gravel
Reaction: pH 6.6 to 7.8
C horizon
Hue: 10YR or 2.5Y
Value: 4 to 7 dry; 3 to 6 moist
Chroma: 2 to 4