LOCATION BIGSANDY MT+NDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, frigid Typic Fluvaquents
TYPICAL PEDON: Bigsandy loam, native grass. (Colors are for moist soil unless otherwise noted)
A--0 to 3 inches; very dark grayish brown (2.5Y 3/2) loam, grayish brown (2.5Y 5/2) dry; moderate fine subangular blocky structure parting to strong fine and medium granular; slightly hard, very friable, slightly sticky and slightly plastic; many fine and very fine and few medium roots; moderately alkaline (pH 8.0); clear smooth boundary. (2 to 6 inches thick)
C--3 to 11 inches; dark grayish brown (2.5Y 4/2) loam consisting of strata of silty clay loam and fine sandy loam, light brownish gray (2.5Y 6/2) dry; few fine faint olive brown (2.5Y 4/4) redoximorphic concentrations; weak medium prismatic structure; hard, very friable to firm, sticky and plastic; many fine and very fine and few medium roots; many very fine and few fine tubular pores; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (0 to 10 inches thick).
Cg1--11 to 32 inches; olive gray (5Y 4/2) loam consisting of strata of silt loam, silty clay loam, and fine sandy loam, gray (5Y 6/1) and light olive gray (5Y 6/2) dry; common fine prominent olive brown (2.5Y 4/4) redoximorphic concentrations; massive; hard, very friable to firm, sticky and plastic; common fine and very fine roots; common very fine tubular pores; few fine masses of lime; few fine masses of gypsum and soluble salts in silty clay loam strata; strongly effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (16 to 23 inches thick).
Cg2--32 to 60 inches; dark gray (5Y 4/1) and olive gray (5Y 4/2) clay loam consisting of strata of loam, silty clay loam, fine sand, and clay, gray (5Y 6/1) and gray (5Y 5/1) dry; common fine prominent olive brown (2.5Y 4/4) redoximorphic concentrations; massive; hard, firm, sticky and plastic; few very fine roots; common very fine tubular pores; few fine masses of gypsum and soluble salts; strongly effervescent; strongly alkaline (pH 8.6).
TYPE LOCATION: Chouteau County, Montana; 1,600 feet east and 50 feet south of the NW corner of sec. 17, T. 28 N., R. 13 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to seasonal high water table - 12 to 24 inches during the period from December to June.
Depth to slowly permeable clay layer - more than 48 inches.
Soil phases - saline
A horizon - Hue: 2.5Y or 10YR
Value: 3 or 4 moist; 4, 5 or 6 dry
Chroma: 1 or 2
Redoximorphic features: Abundance--none to few; Hue--2.5Y; Value--5 or 6 dry
Texture: loam, silt loam or silty clay loam
Clay content: 15 to 35 percent
EC: 2 to 25 mmhos/cm; saline phase 16 to 25 mmhos/cm
Reaction: pH 7.4 to 9.0
When mixed to 7 inches the epipedon has moist value of 4.
C horizon - Hue: 2.5Y or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 1 or 2
Redoximorphic features: Abundance--none or few; Hue--2.5Y; Value--5 or 6 dry
Texture: loam or silty clay loam, consisting of strata of silt loam, clay loam, or fine sandy loam
Clay content: 18 to 35 percent
EC: 2 to 25 mmhos/cm; saline phase 16 to 25 mmhos/cm
Reaction: pH 7.9 to 9.0
Cg1 horizon - Hue: 5Y, 2.5Y or 10YR
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1 or 2
Redoximorphic features: Abundance--common or many; Hue--2.5Y or 10YR; Value--5 or 6 dry, 4 or 5 moist; Chroma--1 or 6
Texture: loam or silty clay loam consisting of strata of silt loam, clay loam, or fine sandy loam
Clay content: 18 to 35 percent
EC: 4 to 25 mmhos/cm; saline phase 16 to 25 mmhos/cm
Reaction: pH 7.9 to 9.0
Cg2 horizon - Hue: 5Y, 2.5Y or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 1 or 2
Redoximorphic features: Abundance--common or many; Hue--2.5Y or 10YR; Value--5 or 6 dry, 4 or 5 moist; Chroma--1 or 6
Texture: silt loam, silty clay loam, loam or clay loam consisting of strata of silt loam, fine sandy loam, fine sand, loamy sand, or clay
Clay content: 15 to 35 percent
EC: 4 to 25 mmhos/cm; saline phase 16 to 25 mmhos/cm
Reaction: pH 7.9 to 9.0
COMPETING SERIES:
Hagga (CO) - have a seasonal high water table at depths of 0 to 12 inches; buried A horizons; elevation over 5,800 feet.
Mckeen (ND) - is very poorly drained with a seasonal high water table at 0 to 12 inches. In addition, Mckeen soils have an EC of less than 4 mmhos/cm throughout.
GEOGRAPHIC SETTING:
Landform - flood plains adjacent to perennial streams.
Elevation - 2,200 to 5,500 feet.
Slopes- 0 to 4 percent.
Parent material - alluvium derived from mixed sources including igneous and sedimentary rocks and glacial till.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 19 inches.
Mean annual air temperature - 41 to 45 degrees F.
Frost-free period - 70 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Glendive, Hanly and Havre soils. These soils are above the Bigsandy soils on the landscape. They do not have an aquic moisture regime.
DRAINAGE AND PERMEABILITY: Poorly drained; moderate or moderately slow permeability in the upper 32 inches of the profile and moderately slow or slow permeability below.
USE AND VEGETATION: Bigsandy soils are used mainly for range and native grass hay production. Potential native vegetation is mainly basin wildrye, tufted hairgrass, northern reedgrass, prairie cordgrass, slender wheatgrass, Canada wildrye, sedges, rushes, willows, and rose.
DISTRIBUTION AND EXTENT: Bigsandy soils are of small extent in north-central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Toole County, Montana, 1991. Series name is from the town of Big Sandy.
REMARKS: Soil interpretation record: MT1078.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - the zone from the surface of the soil to a depth of 7 inches (A and C horizons); redox features below a depth of 11 inches (Cg1 and Cg2 horizons); particle-size control section - the zone from 10 to 40 inches (C, Cg1, and Cg2 horizons). Bigsandy soils have a frigid temperature regime and an aquic moisture regime.