LOCATION VINCOM MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, calcareous, frigid Typic Xerorthents
TYPICAL PEDON: Vincom silt loam, native rangeland (colors are for dry soil unless otherwise noted).
A--0 to 5 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; moderate thin platy structure; soft, very friable, slightly sticky and slightly plastic; common very fine roots; few very fine interstitial pores; moderately alkaline (pH 8.2); clear wavy boundary. (1 to 7 inches thick)
Bk--5 to 22 inches; light gray (10YR 7/2) silty clay loam, brown (10YR 5/3) moist; moderate medium and fine subangular blocky structure; hard, friable, sticky and plastic; few very fine roots; common very fine interstitial pores; few fine masses of lime; strongly effervescent; very strongly alkaline (pH 9.4); gradual irregular boundary. (5 to 17 inches thick)
C--22 to 60 inches; white (10YR 8/2) silty clay loam, pale brown (10YR 6/3) moist; 1/4- to 1/2-inch thick varves; strong medium platy structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; very strongly effervescent; strongly alkaline (pH 8.8).
TYPE LOCATION: Lake County, Montana; 1,320 feet north and 2,640 feet west of the SE corner of sec. 30, T. 22 N., R. 21 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to varves - 6 to 22 inches.
Some pedons have a 2 to 4 inch E/Bw horizon.
A horizon - Value: 6 or 7 dry; 4 or 5 moist
Clay content: 15 to 27 percent
EC: 0 to 2 mmhos/cm
SAR: 0 to 13
Reaction: pH 7.9 to 8.4
This horizon is calcareous in some pedons.
Bk horizon - Value: 7 or 8 dry; 5 or 6 moist
Chroma: 2 or 3
Texture: silt loam or silty clay loam
Clay content: 18 to 35 percent
Calcium carbonate equivalent: 2 to 8 percent
EC: 0 to 2 mmhos/cm
SAR: 0 to 20
Reaction: pH 8.5 to 9.6
C horizon - Value: 7 or 8 dry; 6 or 7 moist
Chroma: 2 or 3
Texture: silt loam or silty clay loam that consist of varves that are silty clay and very fine sandy loam
Clay content: 18 to 35 percent
EC: 0 to 2 mmhos/cm
SAR: 0 to 20
Reaction: pH 8.5 to 9.6
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - dissected lake plains and terraces.
Elevation - 2,500 to 3,200 feet.
Slope- 4 to 65 percent.
Parent material - strongly alkaline, silty glaciolacustrine deposits.
Climate - long, cold winters; moist falls and springs; warm, dry summers.
Mean annual precipitation - 10 to 16 inches.
Mean annual temperature - 41 to 45 degrees F.
Frost-free period - 105 to 125 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Vincom soils are mainly used for rangeland and nonirrigated pastureland. Potential native vegetation is mainly bluebunch wheatgrass, needleandthread, Sandberg bluegrass, prairie junegrass, and Rocky Mountain juniper.
DISTRIBUTION AND EXTENT: Vincom soils are moderately extensive in the "Breaks" along the "Old Lake Missoula" sediment and other similar deposits.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Lake County, Montana, 1991; proposed in Lake County, Montana, 1982.
REMARKS: Soil Interpretation Record: MT0730. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches (A, Bk horizons); a horizon of carbonate accumulation from 5 to 22 inches (Bk horizon); and lake varves from 22 to 60 inches (C horizon). Vincom soils have a frigid temperature regime and a xeric moisture regime bordering on aridic.