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

62 Soil Survey
Oi—0 to 1 inch; slightly decayed needles, twigs, and
leaves; moderately acid (pH 6.0); abrupt smooth
boundary.
E—0 to 6 inches; grayish brown (2.5Y 6/2) very
gravelly loam, dark grayish brown (2.5Y 4/2)
moist; weak fine granular structure; soft, very
friable, nonsticky, nonplastic; few coarse and
common very fine to medium roots; many very
fine and fine pores; 40 percent gravel; neutral
(pH 6.8); abrupt wavy boundary.
Bw1—6 to 17 inches; light brownish gray (2.5Y 6/2)
extremely gravelly sandy loam, dark grayish
brown (2.5Y 4/2) moist; weak fine subangular
blocky structure; soft, very friable, nonsticky,
nonplastic; few fine to coarse and common very
fine roots; many very fine and fine pores; 60
percent gravel; neutral (pH 6.8); clear wavy
boundary.
Bw2—17 to 30 inches; light brownish gray (2.5Y 6/2)
extremely gravelly sandy loam, dark grayish
brown (2.5Y 4/2) moist; weak fine subangular
blocky structure; soft, very friable, nonsticky,
nonplastic; few very fine to coarse roots; many
very fine pores; 60 percent gravel; neutral
(pH 6.8); clear wavy boundary.
BC—30 to 60 inches; light brownish gray (2.5Y 6/2)
extremely gravelly sandy loam, dark grayish
brown (2.5Y 4/2) moist; massive; soft, very
friable, nonsticky, nonplastic; 10 percent cobbles;
60 percent gravel; neutral (pH 6.6).
Range in Characteristics
Soil temperature: 42 to 45 degrees F
Moisture control section: Between 4 and 12 inches
Note: Some pedons have an A horizon.
E horizon
Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 2 or 3
Texture (less than 2 mm): Loam
Clay content: 10 to 20 percent
Content of rock fragments: 15 to 60 percent—0 to
5 percent cobbles; 15 to 55 percent gravel
Reaction: pH 5.1 to 7.3
Bw horizons
Hue: 10YR or 2.5Y
Value: 6 dry; 4 or 5 moist
Chroma: 2 to 4
Texture (less than 2 mm): Sandy loam or loam
Clay content: 10 to 20 percent
Content of rock fragments: 60 to 80 percent—0 to
20 percent cobbles; 25 to 60 percent gravel
Reaction: pH 5.1 to 7.3
BC horizon
Hue: 7.5YR, 10YR, or 2.5Y
Value: 5 to 7 dry; 4 or 5 moist
Chroma: 2 or 3
Texture (less than 2 mm): Sandy loam or fine
sandy loam
Clay content: 10 to 20 percent
Content of rock fragments: 60 to 85 percent—
10 to 25 percent cobbles; 50 to 60 percent
gravel
Reaction: pH 5.1 to 6.6
Ethridge Series
Depth class: Very deep (greater than 60 inches)
Drainage class: Well drained
Permeability: Slow (0.06 to 0.20 inch/hour)
Landform: Fan, hill, stream terrace, terrace,
drainageway on escarpment, swale on
escarpment, drainageway on fan, swale on fan,
drainageway on plain, and swale on plain
Parent material: Clayey alluvium
Slope range: 1 to 35 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, smectitic, frigid Torrertic
Argiustolls
Typical Pedon
Ethridge clay loam, in an area of Ethridge clay
loam, 4 to 8 percent slopes, in an area of rangeland,
1,200 feet south and 1,700 feet west of the northeast
corner of sec. 27, T. 4 N., R. 16 E.; USGS Gibson SW
topographic quadrangle (lat. 46 o 04'16" N.; long.
109 o 42'54" W.)
A—0 to 4 inches; brown (10YR 4/3) clay loam, dark
brown (10YR 3/3) moist; weak fine granular
structure; soft, very friable, moderately sticky,
moderately plastic; common very fine and fine
roots; many very fine and fine pores; neutral
(pH 6.6); clear smooth boundary.
Bt1—4 to 8 inches; brown (10YR 5/3) clay loam, dark
brown (10YR 3/3) moist; weak medium
subangular blocky structure parting to moderate
medium granular; slightly hard, friable,
moderately sticky, moderately plastic; common
very fine and fine roots; many very fine and fine
pores; common distinct discontinuous brown
(7.5YR 4/3) moist; clay films on faces of peds and