LOCATION TRUAXCREEK MT
Established Series
REV. GFB-RJS
03/2012
TRUAXCREEK SERIES
The Truaxcreek series consists of very deep, somewhat poorly drained soils that formed in alluvium derived from mixed sources. These soils occur on stream terraces, flood plains and fan remnants. Slopes are 0 to 8 percent. Mean annual precipitation is about 400 mm, and the mean annual air temperature is about 4 degrees C.
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive Oxyaquic Haplocryolls
TYPICAL PEDON: Truaxcreek loam, in rangeland on a 2 percent slope at an elevation of 2121 meters (colors are for dry soil unless otherwise noted).
Oe--0 to 3 cm; very dark grayish brown (10YR 3/2) mucky peat, black (10YR 2/1) moist; neutral (pH 6.8); clear smooth boundary. (0 to 8 cm thick)
A1--3 to 13 cm; dark grayish brown (10YR 4/2) loam, very dark gray (10YR 3/1) moist; moderate fine and medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and medium roots; many very fine and fine irregular pores; neutral (pH 6.6); clear smooth boundary.
A2--13 to 25 cm; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; moderate fine and medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and medium roots; many very fine and fine irregular pores; finely disseminated calcium carbonate; slightly effervescent; slightly alkaline (pH 7.8); clear wavy boundary. (combined thickness of A1, A2 horizons - 18 to 28 cm)
Bw--25 to 39 cm; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; moderately hard, firm, moderately sticky and slightly plastic; many fine and medium roots; many very fine and fine irregular pores; finely disseminated calcium carbonate; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (8 to 15 cm thick)
Bk--39 to 82 cm; pale brown (10YR 6/3) loam, brown (10YR 5/3) moist; weak medium and coarse subangular blocky structure; moderately hard, firm, very sticky and slightly plastic; few very fine roots; finely disseminated calcium carbonate and 5 percent soft masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (30 to 46 cm thick)
2C--82 to 152 cm; variegated extremely gravelly sand; single grain; loose, nonsticky and nonplastic; 60 percent gravel and 15 percent cobbles; neutral (pH 7.0).
TYPE LOCATION: Beaverhead County, Montana; located about 100 feet north and 800 feet west of the southeast corner of sec. 11, T. 15S, R. 7W; Snowline topographic quadrangle; UTM 12T, 0387626e, 4932490n, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 2 to 5 degrees C.
Thickness of mollic epipedon - 18 to 28 cm
Depth to secondary calcium carbonate accumulation - 28 to 42 cm
Depth to a lithologic discontinuity - 60 to 100 cm
Depth to a seasonally high water table - 60 to 100 cm
A1, A2 horizons
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 1 to 3; dry or moist
Clay content: 18 to 27 percent
Reaction: pH 6.6 to 7.8
Bw horizon
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2 or 3; dry or moist
Texture: loam or clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 1 to 5 percent
Reaction: pH 7.8 to 8.2
Bk horizons
Value: 6 or 7 dry; 5 or 6 moist
Chroma: 2 or 3; dry or moist
Texture: loam or clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 8.0 to 8.4
2C horizon
Texture: loamy sand or sand
Clay content: 1 to 10 percent
Rock fragments: 55 to 85 percent--45 to 75 percent gravel, 0 to 20 percent cobbles
Calcium carbonate equivalent: 0 to 2 percent
Reaction: pH 6.8 to 7.8
COMPETING SERIES:
Turson (WY) - do not have secondary calcium carbonate accumulation
Wisdom (MT) - do not have secondary calcium carbonate accumulation
GEOGRAPHIC SETTING:
Landform - stream terraces, flood plains and fan remnants
Elevation - 1980 to 2270 meters
Slope - 0 to 8 percent
Parent material - alluvium derived from mixed sources
Climate - long, cold winters; moist springs; short warm summers
Mean annual precipitation - 380 to 485 mm
Mean annual air temperature - 1 to 4 degrees C.
Frost-free period - 50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderate over rapid permeability.
USE AND VEGETATION: Truaxcreek soils are used mainly for wildlife, irrigated pasture and rangeland. The vegetation is mainly sedges, rushes, and miscellaneous grasses and forbs.
DISTRIBUTION AND EXTENT: Truaxcreek soils are of small extent in southwestern Montana. MLRAs - 43B, 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Horse Prairie-South Valley Area - Part of Beaverhead County, Montana, 2011; proposed in Beaverhead County, Montana, 2009.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 3 to 26 cm (A1, A2 horizons)
Secondary calcium carbonate accumulation - from 39 to 82 cm (Bk horizon)
Seasonally high water table and lithologic discontinuity - at 82 cm (2C horizon)
Particle-size control section - from 28 to 103 cm (part of Bw, Bk, part of 2C horizons)
Truaxcreek soils have a cryic temperature regime, an ustic moisture regime and an oxyaquic moisture subclass.
Taxonomic version: Eleventh Edition, 2010.
National Cooperative Soil Survey
U.S.A.