LOCATION MONAD MT+COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Alfic Argicryolls
TYPICAL PEDON: Monad loam, grassland (colors are for dry soil unless otherwise noted).
A1--0 to 9 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many fine and very fine roots, few medium roots; 15 percent cobbles and gravel; slightly acid (pH 6.2); clear wavy boundary. (6 to 11 inches thick)
A2--9 to 14 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine and very fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many fine and very fine roots, few medium roots; many fine and very fine pores, few medium pores; very thin continuous gray (10YR 6/1) skeletans coating faces of peds; 15 percent channers; moderately acid (pH 5.8); gradual wavy boundary. (0 to 8 inches thick)
Bt/E--14 to 21 inches; Bt part (80 percent) brown (10YR 5/3) loam, brown (10YR 4/3) moist; E part (20 percent) gray (10YR 6/1) loam, dark gray (10YR 4/1) moist; weak medium prismatic structure parting to moderate fine subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; common fine and very fine roots; many fine and very fine pores, few medium pores; very thin continuous gray (10YR 6/1) skeletans coating continuous faint clay films on faces of peds; 10 percent sandstone channers; moderately acid (pH 5.7); clear wavy boundary. (5 to 17 inches thick)
Bt1--21 to 49 inches; pale brown (10YR 6/3) clay loam, brown (10YR 4/3) moist; weak medium prismatic structure parting to moderate fine and medium blocky structure; extremely hard, firm, very sticky and moderately plastic; few fine and very fine roots; many fine and very fine pores, few medium pores; very thin gray (10YR 6/1) skeletans coating continuous distinct clay films on faces of peds; 10 percent sandstone channers; moderately acid (pH 5.8); gradual wavy boundary. (9 to 24 inches thick)
Bt2--49 to 74 inches; very pale brown (10YR 7/4) stony clay loam, brown (7.5YR 5/4) moist; strong medium and fine blocky structure; extremely hard, firm, very sticky and moderately plastic; many fine and very fine pores, few medium pores; continuous distinct clay films on faces of peds; 15 percent cobbles, 10 percent stones; slightly alkaline (pH 7.4).
TYPE LOCATION: Cascade County, Montana; 700 feet east and 1,340 feet south of the NW corner of the NE 1/4 of sec. 27, T. 17 N., R. 5 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 35 to 41 degrees F.
Moisture control section - between 4 and 12 inches.
Mollic epipedon thickness - 10 to 16 inches.
Some pedons have an E/Bt horizon.
A horizons - Value: 3, 4 or 5 dry; 2 or 3 moist
Chroma: 1 or 2
Texture: loam or fine sandy loam
Clay content: 10 to 27 percent
Rock fragments: 0 to 35 percent--0 to 10 percent cobbles, 0 to 25 percent gravel
Reaction: pH 5.6 to 7.3
Bt/E horizon - Value: Bt part 4, 5, or 6 dry, 4 or 5 moist; E part 6 or 7 dry, 4 or 5 moist
Chroma: Bt part 2, 3 or 4, E part 1, 2 or 3
Texture: loam, clay loam, or sandy clay loam
Clay content: 22 to 35 percent
Rock fragments: 10 to 35 percent--0 to 5 percent cobbles and stones, 10 to 30 percent gravel or channers
Reaction: pH 5.6 to 7.3
Bt horizons - Hue: 10YR or 7.5YR
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 3, 4 or 6
Texture: clay loam, loam, or sandy clay loam
Clay content: 22 to 35 percent
Rock fragments: 10 to 35 percent0 to 15 percent stones, 0 to 15 percent cobbles, 0 to 25 percent gravel or channers
Reaction: pH 5.6 to 7.8
COMPETING SERIES:
Anvik (CO) - has 25 to 35 percent stones and cobbles at depths of 40 to 60 inches; rock fragments in the argillic horizon are stones and cobbles.
Bear Basin (UT) - has strongly or very strongly acid argillic and C horizons; very cobbly sandy loam below the argillic horizon.
Buffork (WY) has a paralithic contact at a depth of 20 to 40 inches.
Slipman (WY) - has a lithic contact of sandstone at depths of 40 to 60 inches.
GEOGRAPHIC SETTING:
Landform - alluvial fans; hills; ground moraines; mountains.
Elevation - 4,600 to 8,100 feet.
Slope - 2 to 60 percent.
Parent material - local alluvium, colluvium, and outwash mainly from argillites, sandstone, and quartzites.
Mean annual precipitation - 14 to 24 inches.
Mean annual temperature - 34 to 39 degrees F.
Frost-free period - 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Libeg, Loggert, and Tigeron soils. These soils contain more than 35 percent rock fragments in the particle-size control section. Loggert and Tigeron soils lack a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Monad soils are used mainly for rangeland. Potential native vegetation is mainly rough fescue, Idaho fescue, Richardson needlegrass, mountain brome, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Monad soils are of moderate extent in west-central Montana and Colorado.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Cascade County, Montana, 1975.
REMARKS: Soil interpretations record: MT0115. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 14 inches (A1, A2 horizons); a glossic horizon from 14 to 21 inches (Bt/E horizon); an argillic horizon from 14 to 74 inches (Bt/E, Bt1, Bt2 horizons); a particle-size control section from 14 to 34 inches (Bt/E, Bt1 horizons). Monad soils have a cryic temperature regime and an ustic moisture regime.