LOCATION SUNBURST MT+WYEstablished Series
TAXONOMIC CLASS: Fine, smectitic, calcareous, frigid Torrertic Ustorthents
TYPICAL PEDON: Sunburst clay, grassland (colors are for dry soil unless otherwise noted).
A--0 to 6 inches; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; moderate very fine granular structure; hard, friable, sticky and plastic; slightly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (2 to 6 inches thick)
Bk1--6 to 13 inches; grayish brown (2.5Y 5/2) clay, dark grayish brown (2.5Y 4/2) moist; weak medium prismatic structure; very hard, friable, sticky and plastic; many fine and very fine pores; many fine and very fine roots; few small pebbles; few masses of lime; strongly effervescent; moderately alkaline (pH 8.4); gradual boundary. (0 to 15 inches thick)
Bk2--13 to 26 inches; grayish brown (2.5Y 5/2) clay, dark olive brown (2.5Y 4/3) moist; moderate coarse prismatic structure; extremely hard, firm, sticky and plastic; many fine pores; many fine and very fine roots; few coarse masses and films of lime; strongly effervescent; moderately alkaline (pH 8.4); gradual boundary. (10 to 26 inches thick)
Bky--26 to 60 inches; light brownish gray (2.5Y 6/2) clay, dark olive brown (2.5Y 4/3) moist; weak medium and coarse blocky structure in upper part and thick platy in lower part; extremely hard, firm, sticky and plastic; few fine and very fine pores and roots; few lignite chips and few small pebbles; few coarse masses of lime; strongly effervescent; many fine nests and seams of gypsum; moderately alkaline (pH 8.4)
TYPE LOCATION: Glacier County, Montana; 400 feet east and 100 feet south of the NW corner of sec. 30, T. 32 N., R. 5 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 and 12 inches; dry in all parts between four-tenths and five-tenths of the cumulative days per year when the soil temperature at a depth of 20 inches is 41 degrees F.
Depth to Bk horizon - 2 to 6 inches.
A By horizon is allowed and is at a depth of 20 inches or greater, it has reaction ranging from pH 6.6 to 7.8, and a gypsum content of 1 to 8 percent.
Soil phases - gravelly, very gravelly.
A horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: loam, clay loam, or clay
Clay content: 20 to 50 percent
Rock fragments: 2 to 60 percent--2 to 50 percent pebbles, 0 to 10 percent cobbles
Reaction: pH 7.4 to 8.4
Bk horizons - Hue: 2.5Y or 5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Texture: clay, clay loam, silty clay loam
Clay content: 35 to 50 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.4
Bky horizon - Hue: 2.5Y or 5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Texture: clay, clay loam, silty clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles, 0 to 10 percent pebbles
Calcium carbonate equivalent: 5 to 15 percent
Gypsum: 1 to 3 percent
Reaction: pH 7.4 to 9.0
COMPETING SERIES:
Nobe (MT) - thin vesicular surface crust; SAR of 13 and greater and ECs of 16 and greater in the particle-size control section; did not form in till.
Orinoco (MT) - 20 to 40 inches deep over a paralithic contact.
Vanda (MT) - SARs greater than 13; ECs greater than 8 mmhos/cm; vesicular surface crust; did not form in till.
GEOGRAPHIC SETTING:
Landform - till plains.
Elevation - 1,900 to 4,000 feet.
Slope- 0 to 80 percent.
Parent material - till.
Climate - long, cold, winters; moist springs; warm summers.
Mean annual precipitation - 10 to 15 inches.
Mean annual temperature - 40 to 45 degrees F.
Frost-free period - 100 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Sunburst soils are used mainly for range, a few areas are cultivated. Potential native vegetation is mainly western wheatgrass, prairie junegrass, blue grama, and threadleaf sedge.
DISTRIBUTION AND EXTENT: Sunburst soil are moderately extensive throughout most of the counties of the till plains of northern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Glacier County, Montana, 1969.
REMARKS: Soil interpretations record: MT0239. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (mixed) (A, Bk1 horizons); horizons of secondary carbonate accumulation (Bk1, Bk2, Bky horizons); a horizon with gypsum accumulations (Bky horizon); a particle-size control section from 10 to 40 inches (Bk1, Bk2, and Bky horizons). Sunburst soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.