LOCATION TRUDAU MT
Established Series
Rev. DES-JJU-RJS
09/2011
TRUDAU SERIES
The Trudau series consists of very deep, well drained soils that formed in alluvium derived from sandstone, siltstone, and shale. These soils are on stream terraces, alluvial fans, fan remnants, flood-plain steps, drainageways and knolls. Slopes are 0 to 15 percent. Mean annual precipitation is about 12 inches, and mean annual air temperature is about 40 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Haplustepts
TYPICAL PEDON: Trudau loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 2 inches; light gray (10YR 7/2) loam, grayish brown (10YR 5/2) moist; weak very fine platy structure parting to moderate very fine granules; soft, very friable, slightly sticky and slightly plastic; many very fine roots; many fine tubular pores; strongly effervescent; strongly alkaline (pH 8.6); abrupt smooth boundary. (2 to 8 inches thick)
Bw--2 to 14 inches; light gray (10YR 7/2) loam, light brownish gray (10YR 6/2) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine irregular and tubular pores; few fine masses of calcium carbonate; strongly effervescent; strongly alkaline (pH 8.6); gradual smooth boundary. (8 to 15 inches thick)
Bk--14 to 30 inches; very pale brown (10YR 7/3) loam, pale brown (10YR 6/3) moist; weak coarse prismatic structure parting to weak medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many irregular and tubular pores; common fine and medium masses of calcium carbonate; violently effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (5 to 20 inches thick)
Bkz--30 to 60 inches; very pale brown (10YR 7/3) loam stratified with sandy loam, pale brown (10YR 6/3) moist; massive; soft, very friable, slightly sticky and nonplastic; few fine roots; many irregular pores; common fine salt crystals; common fine and medium masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.4)
TYPE LOCATION: Madison County, Montana; approximately 1,200 feet north and 1,200 feet west of the southeast corner of sec. 22, T. 8S, R. 5W.
RANGE IN CHARACTERISTICS:
Soil temperature - 40 to 42 degrees F.
Depth to secondary calcium carbonate accumulation - 10 to 23 inches
Depth to salt accumulation - 15 to 40 inches
Phases: reclaimed
A horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 to 7 dry; 3 to 5 moist
Chroma: 2 or 3; dry or moist
Texture: loam, silt loam or clay loam
Clay content: 15 to 30 percent
Rock fragments: 0 to 5 percent gravel
Electrical conductivity: 0 to 2 mmhos/cm
Calcium carbonate equivalent: 1 to 10 percent
Reaction: pH 7.4 to 9.0; reclaimed -- pH 7.4 to 7.8
Bw horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 or 7 dry; 4 to 6 moist
Chroma: 2 to 4; dry or moist
Texture: loam, silt loam or clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 5 percent gravel
Electrical conductivity: 1 to 16 mmhos/cm--reclaimed less than 4 mmhos/cm
Sodium adsorption ratio: less than 5
Calcium carbonate equivalent: 1 to 10 percent
Reaction: pH 7.4 to 9.0; reclaimed -- pH 7.4 to 8.4
Bk horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 to 8 dry; 5 to 7 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
Electrical conductivity: 2 to 16 mmhos/cm; reclaimed -- less than 8 mmhos/cm
Sodium adsorption ratio: 2 to 13
Reaction: pH 7.4 to 9.6
Bkz horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 to 8 dry; 5 to 7 moist
Chroma: 2 to 4; dry or moist
Texture: mainly loam stratified with sandy loam, silt loam or clay loam
Clay content: 18 to 27 percent
Rock fragments: 0 to 15 percent--0 to 10 percent gravel, 0 to 5 percent cobbles
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: 2 to 16 mmhos/cm; reclaimed -- less than 8 mmhos/cm
Sodium adsorption ratio: 2 to 13
Reaction: pH 7.4 to 9.6
COMPETING SERIES:
Coocreek (WY) - do not have a horizon of salt accumulation
Cooers (MT) - do not have a horizon of salt accumulation
Delpoint (MT) - are moderately deep to a paralithic contact
Frandsen (UT) - do not have a horizon of salt accumulation
Spinekop (MT) - have a lithologic discontinuity
Yamacall (MT) - do not have a horizon of salt accumulation
GEOGRAPHIC SETTING:
Landform - stream terraces, alluvial fans, fan remnants, flood-plain steps, drainageways and knolls
Elevation - 3,200 to 6,500 feet
Slope - 0 to 15 percent
Parent material - alluvium derived from sandstone, siltstone, and shale
Climate - long, cold winters; moist springs; cool summers
Mean annual precipitation - 10 to 14 inches
Mean annual air temperature - 38 to 43 degrees F.
Frost-free period - 70 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Trudau soils are used mainly for rangeland; some areas are used for irrigated crops. Potential native vegetation is mainly western wheatgrass, Nuttall alkaligrass, inland saltgrass, rubber rabbitbrush, and greasewood.
DISTRIBUTION AND EXTENT: Trudau soils are moderately extensive in the dry intermountain valley areas in southwestern Montana. MLRA - 44B, 46, 52.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Madison County, Montana, 1983.
REMARKS: Diagnostic horizons and features recognized in the pedon are:
Ochric epipedon - from 0 to 7 inches (A, part of Bw horizons)
Cambic horizon - from 2 to 14 inches (Bw horizon)
Secondary calcium carbonate accumulation - from 14 to 60 inches (Bk, Bkz horizons)
Salt accumulation - from 30 to 60 inches (Bkz horizon)
Particle-size control section - from 10 to 40 inches (part of Bw, Bk, part of Bkz horizons)
Trudau soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
ADDITIONAL DATA: Soil interpretations records - MT0433, MT0434.
National Cooperative Soil Survey
U.S.A.