LOCATION LOSTPRAIRIE MTTentative Series
TAXONOMIC CLASS: Fine-silty, mixed, active, frigid Vitrandic Argiustolls
TYPICAL PEDON: Lostprairie silt loam, rangeland (Colors are for dry soil unless otherwise noted.)
A--0 to 10 inches; dark gray (10YR 4/1) ashy silt loam, black (10YR 2/1) moist; moderate medium subangular blocky structure parting to moderate fine granular; slightly hard, friable, slightly sticky and slightly plastic; few fine and medium roots; slightly effervescent; moderately alkaline (pH 8.1); clear wavy boundary. (7 to 10 inches thick)
2E--10 to 26 inches; light gray (10YR 7/2) silt, brown (10YR 5/3) moist; weak coarse subangular blocky structure parting to moderate thin platy; slightly hard, friable, slightly sticky and slightly plastic; few fine and medium roots; moderately alkaline (pH 7.9); gradual wavy boundary. (3 to 16 inches thick)
2Bt--26 to 44 inches; light gray (2.5Y 7/2) silty clay loam, grayish brown (2.5Y 5/2) moist; moderate coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine roots; few distinct clay films on faces of peds; few fine distinct yellowish brown (10YR 5/6) redox concentrations; slightly alkaline (pH 7.8); gradual wavy boundary. (10 to 20 inches thick)
2C1--44 to 52 inches; pale yellow (5Y 8/2) silt loam, light olive gray (5Y 6/2) moist; massive; hard, firm, moderately sticky and moderately plastic; common fine and medium distinct yellowish brown (10YR 5/6) redox concentrations; slightly alkaline (pH 7.6); gradual wavy boundary. (6 to 18 inches thick)
2C2--52 to 60 inches; pale yellow (5Y 8/2) silt, light olive gray (5Y 6/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common fine and medium distinct yellowish brown (10YR 5/6) redox concentrations; slightly alkaline (pH 7.6).
TYPE LOCATION: Flathead County, Montana; 1,600 feet east and 1200 feet north of the southwest corner of sec. 21, T. 27 N., R. 25 W. Mcgregor Peak topographic quadrangle. UTM zone 11: Northing 5327600, Easting 661640.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 42 to 45 degrees F.
Depth to seasonal high water table - 24 to 42 inches.
A horizon
Hue - 2.5Y or 10YR
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 1 or 2
Texture - ashy silt loam
Clay content - 15 to 27 percent
Bulk density: 1.0 to 1.4 g/cm3
Volcanic glass: 5 to 30 percent
Acid oxalate extractable Al + 1/2 Fe: .4 to 1.0 percent
EC - less than 2 mmhos/cm
SAR - less than 13
Reaction - pH 6.6 to 8.4
2E horizon
Hue - 10YR or 2.5Y
Value - 6 or 7 dry, 3 to 5 moist
Chroma - 2 or 3
Texture - silt, silt loam, or very fine sandy loam
Clay content - 4 to 20 percent
EC - less than 2 mmhos/cm
SAR - less than 13
Reaction - pH 7.2 to 8.0
2Bt horizon
Hue - 2.5Y
Value - 5 to 8 dry, 4 to 6 moist
Chroma - 2 to 4
Texture - silty clay loam or silt loam
Clay content - 18 to 35 percent
EC - less than 2 mmhos/cm
SAR - less than 13
Reaction - pH 7.2 to 8.4
2C1 horizon
Hue - 2.5Y or 5Y
Value - 6 to 8 dry, 4 to 6 moist
Chroma - 2 to 4
Texture - silt loam or very fine sandy loam
Clay content - 10 to 27 percent
EC - less than 2 mmhos/cm
SAR - less than 13
Reaction - pH 7.2 to 8.4
2C2 horizon
Hue - 2.5Y or 5Y
Value - 6 to 8 dry, 4 to 6 moist
Chroma - 1 to 3
Texture - silt loam, silt, or very fine sandy loam
Clay content - 5 to 20 percent
EC - less than 2 mmhos/cm
SAR - less than 13
Reaction - pH 7.2 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Lostprairie soils are on lake terraces and alluvial fans in mountain valleys. Slopes range from 0 to 4 percent. These soils formed in mixed lacustrine sediments with a component of volcanic ash in the surface layer. Elevation is 3,400 to 3,700 feet. The average annual air temperature is 43 to 47 degrees F, average annual precipitation is 15 to 22 inches, and the average frost-free period is from 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Whitebear(T), Dahlake(T), Meadowpeak, McLangor, and Barzee soils. Whitebear(T) soils are on lake terraces and alluvial fans, are coarse-silty and have high SAR values. Dahlake(T) soils are on lake terraces, have an aquic moisture regime and high SAR values. Meadowpeak, McLangor, and Barzee soils are on floodplains and closed depressions. Meadowpeak soils are coarse-silty and have an aquic moisture regime. McLangor soils have a histic epipedon. Barzee soils consist of organic materials.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained, moderately slow permeability.
USE AND VEGETATION: These soils are used for rangeland, wildlife habitat, and watershed. Potential natural vegetation is mainly Fowl bluegrass, Alkali bluegrass, Alkali sacaton, Alkali cordgrass, Basin wildrye, and Shrubby cinquefoil.
DISTRIBUTION AND EXTENT: Northwestern Montana. This soil is not extensive. MLRA 44A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Flathead County, Montana, 2003. The name is coined from Lost Prairie, a local place name in Flathead County, Montana.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 10 inches (A horizon)
Albic horizon - the zone from 10 to 26 inches (2E horizon)
Argillic horizon - the zone from 26 to 44 inches (2Bt horizon)
Particle-size control section - the zone from 26 to 44 inches (2Bt horizon)
Lostprairie soils have an ustic moisture regime and a frigid temperature regime.
ADDITIONAL DATA: NSSL S92MT-029-003