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

Sweet Grass County Area, Montana—Part I 91
Clay content: 18 to 35 percent
Calcium carbonate equivalent: 5 to 12 percent
Electrical conductivity: 2 to 8 mmhos/cm
Sodium adsorption ratio: 1 to 13
Reaction: pH 7.9 to 9.0
By horizon
Hue: 10YR or 2.5Y
Value: 5 to 7 dry; 4 to 6 moist
Chroma: 2 to 4
Texture (less than 2 mm): Stratified silt loam and
very fine sandy loam
Clay content: 18 to 27 percent
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: 2 to 8 mmhos/cm
Sodium adsorption ratio: 1 to 13
Reaction: pH 7.9 to 9.0
Lymanson Series
Depth class: Moderately deep (20 to 40 inches)
Drainage class: Well drained
Permeability: Moderate (0.6 to 2.0 inches/hour)
Landform: Mountain
Parent material: Loamy residuum weathered from
sandstone and siltstone
Slope range: 2 to 50 percent
Elevation range: 5,500 to 7,500 feet
Mean annual precipitation: 20 to 25 inches
Mean annual air temperature: 36 to 38 degrees F
Frost-free period: 50 to 70 days
Taxonomic Class: Fine-loamy, mixed, superactive
Ustic Argicryolls
Typical Pedon
Lymanson loam, in an area of Cheadle-Lymanson-
Gilispie complex, 2 to 15 percent slopes, in an area
of rangeland, 2,200 feet south and 1,100 feet west
of the northeast corner of sec. 36, T. 2 S., R. 12 E.;
USGS McLeod Basin topographic quadrangle (lat.
45 o 37'12" N.; long. 110 o 10'51" W.)
A1—0 to 4 inches; very dark grayish brown (10YR
3/2) loam, black (10YR 2/1) moist; weak very fine
and fine granular structure; soft, very friable,
nonsticky, slightly plastic; many very fine and fine
roots; many very fine and fine pores; slightly acid
(pH 6.2); clear smooth boundary.
A2—4 to 8 inches; very dark grayish brown (10YR
3/2), loam, very dark brown (10YR 2/2) moist;
weak medium subangular blocky structure
parting to weak fine granular; soft, very friable,
slightly sticky, slightly plastic; many very fine and
fine roots; many very fine and fine pores; slightly
acid (pH 6.2); clear smooth boundary.
Bt1—8 to 15 inches; brown (10YR 5/3) clay loam,
brown (10YR 4/3) moist; moderate medium
subangular blocky structure; slightly hard, friable,
moderately sticky, moderately plastic; many very
fine and fine roots; many very fine and fine pores;
common distinct discontinuous dark yellowish
brown (10YR 4/4) moist; clay films on faces of
peds and lining pores; neutral (pH 6.8); clear
smooth boundary.
Bt2—15 to 21 inches; pale brown (10YR 6/3) clay
loam; brown (10YR 5/3) moist; moderate medium
and coarse subangular blocky structure; slightly
hard, friable, moderately sticky, moderately
plastic; many fine roots; many fine pores;
common faint discontinuous yellowish brown
(10YR 5/4) moist; clay films on faces of peds and
lining pores; neutral (pH 7.0); abrupt smooth
boundary.
Bk—21 to 31 inches; light gray (2.5Y 7/2) gravelly
loam, light brownish gray (2.5Y 6/2) moist; weak
coarse prismatic structure; soft, very friable,
slightly sticky, slightly plastic; common fine roots;
many very fine and fine pores; fine and medium
soft masses of lime; 17 percent gravel; strongly
effervescent; moderately alkaline (pH 8.0); clear
smooth boundary.
Cr—31 to 60 inches; thinly bedded calcareous
sandstone and siltstone.
Range in Characteristics
Soil temperature: 39 to 44 degrees F
Moisture control section: Between 4 and 12 inches
Thickness of the mollic epipedon: 7 to 15 inches
Depth to the Bk horizon: 10 to 23 inches
Depth to the Cr horizon: 20 to 40 inches
Note: Some pedons have a Btk horizon.
A horizons
Hue: 7.5YR, 10YR, or 2.5Y
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 1 to 3
Texture (less than 2 mm): Loam
Clay content: 20 to 27 percent
Content of rock fragments: 0 to 35 percent—0 to
20 percent stones and cobbles; 0 to 15 percent
gravel
Reaction: pH 6.6 to 8.4
Bt horizons
Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 4