LOCATION MADBEAVER MT
Established Series
Rev. GFB-KTS-RJS
05/2011
MADBEAVER SERIES
The Madbeaver series consists of very deep, somewhat poorly drained soils that formed in calcareous alluvium. These soils are on alluvial fans, stream terraces and drainageways. Slopes are 0 to 4 percent. Mean annual precipitation is about 12 inches, and mean annual air temperature is about 42 degrees F.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Typic Calciustepts
TYPICAL PEDON: Madbeaver silt loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 9 inches; gray (10YR 6/1) silt loam, dark gray (10YR 4/1) moist; weak medium prismatic structure parting to moderate fine and medium subangular blocky; slightly hard, friable, moderately sticky and slightly plastic; many very fine, and few fine and medium roots; many very fine and common fine interstitial pores; finely disseminated calcium carbonate; violently effervescent; slightly alkaline (pH 7.8); clear smooth boundary. (4 to 10 inches thick)
Bk1--9 to 25 inches; very pale brown (10YR 8/2) silt loam, pale brown (10YR 6/3) moist; weak medium prismatic structure parting to moderate fine and medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine roots; many very fine and few fine interstitial pores; common threads and masses of calcium carbonate; violently effervescent; strongly alkaline (pH 8.6); clear smooth boundary.
Bk2--25 to 33 inches; light gray (10YR 7/2) loam, light brownish gray (10YR 6/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine interstitial pores; few fine prominent strong brown (7.5YR 5/6) redox concentrations; common threads and masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (combined thickness of Bk1, Bk2 horizons - 15 to 30 inches)
C--33 to 48 inches; light gray (2.5Y 7/2) fine sandy loam, light brownish gray (2.5Y 6/2) moist; massive; soft, very friable, slightly sticky and nonplastic; few very fine roots; few very fine interstitial pores; common fine, medium and coarse prominent strong brown (7.5YR 5/6) redox concentrations; finely disseminated calcium carbonate; violently effervescent; moderately alkaline (pH 8.3); clear abrupt boundary. (5 to 19 inches thick)
2Cg--48 to 60 inches; pale yellow (5Y 8/2) extremely gravelly loamy sand, light olive gray (5Y 6/2) moist; single grain; loose, nonsticky and nonplastic; 50 percent gravel and 15 percent cobbles; finely disseminated calcium carbonate; strongly effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Beaverhead County, Montana; 150 feet south and 700 feet east of the NW corner of sec. 6, T. 8S, R. 8W; Dillon West topographic quadrangle; Lat. 45 degrees, 10 minutes, 26 seconds N., and long. 112 degrees, 38 minutes, 16 seconds W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 40 to 47 degrees F.
Depth to calcic horizon - 4 to 10 inches
Depth to lithologic discontinuity - 40 to 60 inches
Depth to seasonal high water table - 24 to 42 inches
Note: Some pedons may have a thin O horizon at the surface.
A horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 1 or 2; dry or moist
Texture: silt loam or silty clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 10 percent gravel
Calcium carbonate equivalent: 5 to 25 percent
Reaction: 7.4 to 8.4
Bk horizons
Hue: 10YR or 2.5 Y; dry or moist
Value: 6 to dry; 4 to 6 moist
Chroma: 1 to 3; dry or moist
Texture: silt loam, silty clay loam, loam or sandy clay loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 25 percent gravel
Calcium carbonate equivalent: 15 to 40 percent
Reaction: 7.9 to 8.6
C horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 to 8 dry; 4 to 6 moist
Chroma: 1 to 3; dry or moist
Texture: fine sandy loam, sandy clay loam, loam, silt loam or silty clay loam
Clay content: 15 to 35 percent
Rock fragments: 0 to 25 percent gravel
Calcium carbonate equivalent: 10 to 40 percent
Reaction: 7.4 to 8.4
2Cg horizon
Hue: 5Y or 2.5Y; dry or moist
Value: 6 to 8 dry; 5 or 6 moist
Chroma: 2 or 3; dry or moist
Texture: loamy sand, sand, loamy coarse sand or coarse sand
Clay content: 0 to 10 percent
Rock fragments: 35 to 80 percent gravel, 0 to 20 percent cobbles
Calcium carbonate equivalent: 5 to 30 percent
Reaction: 7.9 to 8.6
COMPETING SERIES:
Opechekahta (SD) - do not have a seasonally high water table within 100 cm
Zahill (MT) - do not have a seasonally high water table within 100 cm
GEOGRAPHIC SETTING:
Landform - alluvial fans, stream terraces and drainageways
Elevation - 4,500 to 6,800 feet
Slope - 0 to 4 percent
Parent material - calcareous alluvium
Climate - long cold winters; moist springs; warm summers
Mean annual precipitation - 10 to 14 inches
Mean annual air temperature - 39 to 45 degrees F.
Frost-free season - 70 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderate permeability to the 2Cg horizon and rapid permeability below.
USE AND VEGETATION: Used mainly for rangeland, pasture, and hay. The potential native vegetation is mainly basin wildrye, western wheatgrass, wild iris, sedges, rushes and forbs.
DISTRIBUTION AND EXTENT: Madbeaver soils are of small extent in southwest Montana. MLRA - 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Beaverhead County, Montana, 2001.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from 0 to 9 inches (A horizon)
Calcic horizon - from 9 to 33 inches (Bk1, Bk2 horizons)
Lithologic discontinuity - at 48 inches (2Cg horizon)
Particle-size control section - from 10 to 40 inches (part of Bk1, Bk2, and part of C horizons)
Madbeaver soils have a frigid temperature regime, an ustic moisture regime and an oxyaquic moisture subclass.
Classification changes: The Madbeaver series was reclassified from Aridic Calciustepts to Typic Calciustepts on 5/6/2011.
National Cooperative Soil Survey
U.S.A.