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

136 Soil Survey
moderately sticky, moderately plastic; many
continuous distinct dark brown (7.5YR 3/2) moist;
clay films on faces of peds and lining pores; few
fine and medium roots; many very fine pores;
1 percent gravel; slightly alkaline (pH 7.6); abrupt
smooth boundary.
2Bk1—13 to 19 inches; light gray (10YR 7/2) sandy
clay loam, pale brown (10YR 6/3) moist; weak
coarse prismatic structure; slightly hard, very
friable, slightly sticky, slightly plastic; few fine
roots; common fine pores; common large masses
of lime; 5 percent gravel; violently effervescent;
moderately alkaline (pH 8.4); clear smooth
boundary.
2Bk2—19 to 28 inches; white (10YR 8/2) gravelly
sandy loam, light gray (10YR 7/2) moist; weak
coarse prismatic structure; soft, very friable,
nonsticky, nonplastic; common fine and medium
pores; common large masses of lime; many
distinct carbonate coats on rock fragments;
15 percent gravel; 5 percent cobbles; violently
effervescent; moderately alkaline (pH 8.4); clear
smooth boundary.
3Bk3—28 to 43 inches; light gray (10YR 7/2) very
gravelly loamy coarse sand, yellowish brown
(10YR 5/4) moist; single grain; loose, nonsticky,
nonplastic; continuous distinct carbonate coats
on undersides of rock fragments; 35 percent
gravel; 10 percent cobbles; violently effervescent;
moderately alkaline (pH 8.4); gradual smooth
boundary.
3C—43 to 60 inches; pale brown (10YR 6/3)
extremely gravelly coarse sand, yellowish brown
(10YR 5/4) moist; single grain; loose, nonsticky,
nonplastic; few distinct carbonate coats on
undersides of rock fragments; 45 percent gravel;
20 percent cobbles; 10 percent stones; strongly
effervescent; moderately alkaline (pH 8.4).
Range in Characteristics
Soil temperature: 42 to 47 degrees F
Moisture control section: Between 4 and 12 inches
Thickness of the mollic epipedon: 7 to 15 inches
Depth to the 2Bk horizon: 10 to 20 inches
Depth to the 3Bk horizon: 20 to 40 inches
A horizon
Hue: 7.5YR or 10YR
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture (less than 2 mm): Loam, clay loam, or
clay
Clay content: 20 to 50 percent
Content of rock fragments: 0 to 25 percent—0 to
5 percent cobbles; 0 to 20 percent gravel
Reaction: pH 6.6 to 7.8
Bt horizon
Hue: 7.5YR or 10YR
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 4
Texture (less than 2 mm): Clay loam or clay
Clay content: 35 to 45 percent
Content of rock fragments: 0 to 25 percent—0 to
5 percent cobbles; 0 to 20 percent gravel
Reaction: pH 6.6 to 7.8
2Bk horizons
Hue: 10YR or 2.5Y
Value: 5 to 8 dry; 4 to 7 moist
Chroma: 2 to 4
Texture (less than 2 mm): Sandy clay loam, loam,
clay loam, or sandy loam
Clay content: 10 to 30 percent
Content of rock fragments: 5 to 35 percent—0 to
10 percent cobbles; 5 to 25 percent gravel
Calcium carbonate equivalent: 15 to 50 percent
Reaction: pH 7.4 to 8.4
3Bk horizon
Hue: 10YR or 2.5Y
Value: 5 to 7 dry; 4 to 6 moist
Chroma: 2 to 4
Texture (less than 2 mm): Loamy coarse sand,
loamy sand, sand, or coarse sand
Clay content: 0 to 10 percent
Content of rock fragments: 35 to 80 percent—0 to
15 percent stones; 5 to 25 percent cobbles;
30 to 45 percent gravel
Calcium carbonate equivalent: 5 to 20 percent
Reaction: pH 7.4 to 8.4
3C horizon
Hue: 10YR or 2.5Y
Value: 5 to 7 dry; 4 to 6 moist
Chroma: 2 to 4
Texture (less than 2 mm): Coarse sand, sand, or
loamy coarse sand
Clay content: 0 to 10 percent
Content of rock fragments: 35 to 80 percent—0 to
15 percent stones; 5 to 25 percent cobbles;
30 to 45 percent gravel