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

Sweet Grass County Area, Montana—Part I 99
Typical Pedon
Meagher gravelly loam, in an area of Meagher
gravelly loam, 2 to 8 percent slopes, in an area of
rangeland, 2,800 feet south and 2,200 feet west of
the northeast corner of sec. 6, T. 2 S., R. 13 E.; USGS
McLeod topographic quadrangle (lat. 45 o 41'22" N.;
long. 110 o 02'29" W.)
A—0 to 7 inches; dark grayish brown (10YR 4/2)
gravelly loam, very dark grayish brown (10YR
3/2) moist; moderate medium subangular blocky
structure parting to weak fine and medium
granular; slightly hard, friable, slightly sticky,
slightly plastic; common fine and many very fine
roots; common fine and many very fine pores;
10 percent gravel; 5 percent cobbles; neutral
(pH 6.6); abrupt smooth boundary.
Bt1—7 to 12 inches; yellowish brown (10YR 5/4) clay
loam, brown (10YR 4/3) moist; moderate coarse
prismatic structure parting to moderate fine and
medium subangular blocky; moderately hard,
firm, moderately sticky, moderately plastic;
common very fine and fine roots; common fine
and many very fine pores; common faint
discontinuous dark yellowish brown (10YR 4/4),
moist; clay films on faces of peds and lining
pores; 10 percent gravel; neutral (pH 6.8); clear
smooth boundary.
Bt2—12 to 19 inches; light yellowish brown (10YR
6/4) clay loam, dark yellowish brown (10YR 4/4)
moist; moderate coarse prismatic structure
parting to moderate medium and coarse
subangular blocky; moderately hard, firm,
moderately sticky, moderately plastic; common
very fine and fine roots; common fine and many
very fine pores; common faint discontinuous dark
yellowish brown (10YR 4/4) moist; clay films on
faces of peds and lining pores; 10 percent gravel;
2 percent cobbles; neutral (pH 7.2); abrupt
smooth boundary.
Bk1—19 to 30 inches; very pale brown (10YR 8/3)
gravelly loam, pale brown (10YR 6/3) moist; weak
medium and coarse subangular blocky structure;
soft, friable, slightly sticky, slightly plastic; few
very fine roots; common fine and many very fine
pores; 20 percent gravel; common fine and
medium masses of lime; violently effervescent;
moderately alkaline (pH 8.2); clear smooth
boundary.
2Bk2—30 to 60 inches; very pale brown (10YR 8/2)
very gravelly sandy loam, light brownish gray
(10YR 6/2) moist; weak medium and coarse
subangular blocky structure; soft, friable, slightly
sticky, slightly plastic; few fine and many very
fine pores; many carbonate coats on rock
fragments; many fine and medium masses of
lime; 40 percent gravel; 10 percent cobbles;
violently effervescent; moderately alkaline
(pH 8.4).
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 12 inches
Depth to the Bk horizon: 11 to 20 inches
Depth to the 2Bk horizon: 20 to 35 inches
A horizon
Hue: 7.5YR or 10YR
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture (less than 2 mm): Loam
Clay content: 18 to 27 percent
Content of rock fragments: 0 to 35 percent—0 to
15 percent stones and cobbles; 0 to
20 percent gravel
Reaction: pH 6.6 to 7.8
Bt horizons
Hue: 7.5YR or 10YR
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 3 or 4
Texture (less than 2 mm): Clay loam or loam
Clay content: 20 to 35 percent
Content of rock fragments: 0 to 35 percent—0 to
5 percent stones and cobbles; 0 to 30 percent
gravel
Reaction: pH 6.6 to 7.8
Bk1 horizon
Hue: 10YR or 2.5Y
Value: 7 or 8 dry; 6 or 7 moist
Chroma: 2 to 4
Texture (less than 2 mm): Loam or sandy loam
Clay content: 18 to 27 percent
Content of rock fragments: 5 to 35 percent—0 to
5 percent cobbles; 5 to 30 percent gravel
Calcium carbonate equivalent: 15 to 40 percent
Gypsum content: 0 to 1 percent
Reaction: pH 7.4 to 8.4
2Bk2 horizon
Hue: 10YR or 2.5Y
Value: 7 or 8 dry; 5 to 7 moist
Chroma: 2 to 4
Texture (less than 2 mm): Sandy loam, loam, or
sandy clay loam
Clay content: 10 to 25 percent
Content of rock fragments: 35 to 70 percent—0 to
10 percent cobbles; 35 to 60 percent gravel