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

Sweet Grass County Area, Montana—Part I 21
friable, very sticky, very plastic; common very fine
roots; common fine pores; common distinct
strong brown (7.5YR 4/6) moist; clay films on
faces of peds; neutral (pH 6.8); clear wavy
boundary.
Bk—23 to 26 inches; pale brown (10YR 6/3) loam,
yellowish brown (10YR 5/4) moist; weak medium
prismatic structure parting to weak medium
subangular blocky; slightly hard, friable,
moderately sticky, moderately plastic; common
very fine roots; few fine pores; few fine soft
masses of lime; strongly effervescent; moderately
alkaline (pH 8.0); clear wavy boundary.
Cr—26 to 60 inches; interbedded semiconsolidated
shale and hard sandstone; slightly effervescent.
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 12 inches
Depth to the Bk horizon: 12 to 30 inches
Depth to the Cr horizon: 20 to 40 inches
A horizons
Hue: 7.5YR, 10YR, or 2.5Y
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture (less than 2 mm): Loam, clay loam, or
silty clay loam
Clay content: 20 to 35 percent
Content of rock fragments: 0 to 35 percent—0 to
10 percent stones and cobbles; 0 to 25 percent
gravel or channers
Reaction: pH 6.1 to 7.3
Bt1 horizon
Hue: 7.5YR, 10YR, or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 to 4
Texture (less than 2 mm): Clay loam, clay, or silty
clay
Clay content: 35 to 50 percent
Content of rock fragments: 0 to 10 percent—0 to
5 percent stones and cobbles; 0 to 5 percent
gravel or channers
Reaction: pH 6.6 to 8.4
Bt2 horizon
Hue: 7.5YR, 10YR, or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4
Texture (less than 2 mm): Clay loam, clay, or silty
clay
Clay content: 35 to 50 percent
Content of rock fragments: 0 to 10 percent—0 to
5 percent stones and cobbles; 0 to 5 percent
gravel or channers
Reaction: pH 6.6 to 8.4
Bk horizon
Hue: 7.5YR, 10YR, or 2.5Y
Value: 6 to 8 dry; 5 to 7 moist
Chroma: 2 to 4
Texture (less than 2 mm): Loam or clay loam
Clay content: 25 to 40 percent
Content of rock fragments: 0 to 35 percent—0 to
5 percent stones and cobbles; 0 to 30 percent
gravel or channers
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.4 to 9.0
Absher Family
Depth class: Very deep (greater than 60 inches)
Drainage class: Somewhat poorly drained
Permeability: Very slow (less than 0.06 inch/hour)
Landform: Flood plain and stream terrace
Parent material: Silty and clayey alluvium
Slope range: 0 to 8 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, smectitic, frigid Leptic
Torrertic Natrustalfs
Typical Pedon
Absher clay (when mixed), in an area of Soapcreek-
Absher family complex, 0 to 4 percent slopes, in an
area of rangeland, 2,000 feet south and 1,200 feet
east of the northwest corner of sec. 18, T. 4 N.,
R. 15 E.; USGS Melville topographic quadrangle
(lat. 46 o 05'54" N.; long. 109 o 54'35" W.)
E—0 to .5 inch; light brownish gray (10YR 6/2) silty
clay loam, dark grayish brown (10YR 4/2) moist;
weak thin platy structure parting to weak fine and
medium granular; moderately hard, friable,
moderately sticky, moderately plastic; common
very fine roots; common very fine pores; slightly
effervescent; moderately alkaline (pH 8.4); abrupt
broken boundary.
Btn—.5 to 4 inches; grayish brown (10YR 5/2) clay,
very dark grayish brown (10YR 4/2) moist; strong
coarse columnar structure parting to moderate
medium and coarse angular blocky; very hard,