LOCATION JUDCO MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Ustivitrandic Haplocryepts
TYPICAL PEDON: Judco very gravelly ashy sandy loam, in forest (colors are for dry soil unless otherwise noted).
Oi--0 to 0.5 inch; partially decomposed needles, twigs and leaves.
Oe--0.5 to 2 inches; well decomposed needles, twigs and leaves.
A1--2 to 4 inches; dark gray (10YR 4/1) very gravelly ashy sandy loam, very dark brown (10YR 2/2) moist; moderate medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine roots and few medium roots; 10 percent cobbles and 30 percent gravel; strongly acid (pH 5.4); clear wavy boundary. (0 to 3 inches thick)
A2--4 to 6 inches; gray (10YR 5/1) very gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium granular structure; slightly hard, very friable, slightly sticky and nonplastic; many very fine and fine roots and few medium and coarse roots; many very fine pores; 10 percent cobbles and 30 percent gravel; moderately acid (pH 5.6); clear wavy boundary. (2 to 6 inches thick)
Bw--6 to 12 inches; yellowish brown (10YR 5/4) very gravelly ashy sandy loam, dark yellowish brown (10YR 4/4) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; slightly hard, very friable, slightly sticky and nonplastic; many very fine and fine roots and few medium and coarse roots; many very fine pores; 10 percent cobbles and 30 percent gravel; moderately acid (pH 6.0); clear wavy boundary.
BC1--12 to 23 inches; light gray (2.5Y 7/2) very gravelly ashy sandy loam, dark grayish brown (2.5Y 4/2) moist; weak medium and coarse subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and fine roots; common fine pores; 10 percent cobbles and 45 percent gravel; slightly acid (pH 6.4); gradual wavy boundary.
BC2--23 to 40 inches; light gray (2.5Y 7/2) very gravelly ashy sandy clay loam, grayish brown (2.5Y 5/2) moist; weak coarse subangular blocky structure; slightly hard, very friable, nonsticky and slightly plastic; common very fine and fine roots and few medium roots; common fine pores; 5 percent cobbles and 45 percent gravel; neutral (pH 6.6); gradual wavy boundary. (Combined thickness of B horizons is 24 to 40 inches.)
C--40 to 58 inches; light gray (10YR 7/2) very gravelly ashy sandy clay loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, very friable, slightly sticky and nonplastic; few very fine, fine and medium roots; 5 percent cobbles and 45 percent gravel; neutral (pH 6.6); clear wavy boundary.
Cr--58 to 60 inches; light gray (10YR 7/2) decomposing welded tuff bedrock that crushes to very gravelly ashy sandy loam; neutral (pH 6.6).
TYPE LOCATION: Deer Lodge County, Montana; 400 feet east and 2100 feet south of the NW corner of sec. 14, T. 3 N., R. 11 W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 32 to 40 degrees F.
Mean summer soil temperature - 40 to 46 degrees F.
Moisture control section - between 4 and 12 inches.
Volcanic glass - 20 to 50 percent in the coarse silt and sand fraction.
Acid Oxalate Al + 1/2 Fe - .12 to .20 percent
Depth to Cr horizon - 50 to 60 inches.
Surface stones or boulders - 0 to 0.1 percent.
A1 horizon - Hue: 10YR or 2.5Y
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 1 or 2
Texture: ashy loam, ashy sandy loam or ashy sandy clay loam
Clay content: 10 to 27 percent
Rock fragments: 15 to 60 percent--0 to 30 percent cobbles and stones, 15 to 30 percent gravel
Reaction: pH 5.1 to 6.5
A2 horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry, 3, 4 or 5 moist
Chroma: 1 or 2
Texture: ashy loam, ashy sandy loam or ashy sandy clay loam
Clay content: 18 to 27 percent
Rock fragments: 35 to 60 percent--5 to 15 percent cobbles and stones, 30 to 45 percent gravel
Reaction: pH 5.1 to 6.5
Bw horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2, 3 or 4
Texture: ashy loam, ashy sandy loam or ashy sandy clay loam
Clay content: 18 to 27 percent
Rock fragments: 35 to 55 percent--5 to 15 percent cobbles and stones, 30 to 40 percent gravel
Reaction: pH 5.6 to 7.3
BC and C horizons - Hue: 10YR, 2.5Y or 5Y
Value: 6 or 7 dry; 4, 5 or 6 moist
Chroma: 1 or 2
Texture: ashy loam, ashy sandy loam or ashy sandy clay loam
Clay content: 15 to 27 percent
Rock fragments: 35 to 60 percent--5 to 15 percent cobbles and stones; 30 to 45 percent gravel
Reaction: pH 5.6 to 7.3
COMPETING SERIES:
Frankcreek (WA) - does not have a paralithic contact above 60 inches; has a xeric moisture regime.
Hartop (WA) - has a lithic contact at 20 to 40 inches; has a xeric moisture regime.
Karloff (MT) - has a paralithic contact at 20 to 38 inches; has less than 18 percent clay in the particle-size control section.
Karu (WA) - has a xeric moisture regime.
Koffgo (ID) - has a udic moisture regime.
Torpy (MT) - does not have a paralithic contact above 60 inches; has less than 18 percent clay in the particle-size control section.
Verhart (WA) - has a xeric moisture regime; has a lithic contact at 20 to 40 inches.
Volmont (WA) - has a xeric moisture regime; has a lithic contact at 20 to 40 inches.
Wellsfar (WA) - has a paralithic contact at 20 to 40 inches; has a xeric moisture regime.
Winsand (WA) - has a xeric moisture regime.
GEOGRAPHIC SETTING:
Landform- alluvial fans, footslopes, mountains and hills.
Elevation - 5,000 to 8,000 feet.
Slope - 15 to 70 percent.
Parent material - colluvium, alluvium and residuum from welded tuff or rhyolite bedrock.
Climate - long, cold winters; cool, moist springs; short, cool summers.
Mean annual precipitation - 15 to 30 inches.
Mean annual air temperature - 30 to 38 degrees F.
Frost-free period - 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Judco soils are mainly used for woodland, understory grazing, watershed and as wildlife habitat. The potential overstory vegetation is mainly subalpine fir, lodgepole pine, Englemann spruce and whitebark pine. Understory vegetation is mainly grouse whortleberry, elk sedge, Oregongrape, common beargrass, and pinegrass.
DISTRIBUTION AND EXTENT: Judco soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998; proposed in Deer Lodge County, Montana, 1996.
REMARKS: Soil interpretive record: MT1751, MT3231. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from 2 to 6 inches (A horizons); a cambic horizon from 6 to 23 inches (Bw and BC1 horizons); a particle size control section from 10 to 40 inches (part of Bw, BC1 and BC2 horizons); a layer of decomposing welded tuff from 58 to 60 inches (Cr horizon). Judco soils have a cryic temperature regime and an ustic moisture regime.
The 3/2008 description reflects a change in classification from Loamy-skeletal, mixed, superactive Vitrandic Eutrocryepts to Loamy-skeletal, mixed, superactive Ustivitrandic Haplocryepts due to revision of the cryepts great groups and subgroups. The competing series section was not updated and should be reviewed after all the cryepts have been re-classified.