LOCATION WELTER MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Aridic Dystrustepts
TYPICAL PEDON: Welter silty clay loam, forested (colors are for dry soil unless otherwise noted).
Oi--0 to 1 inch; pine cones, needles, twigs, and humus; abrupt smooth boundary.
E--1 to 5 inches; light brownish gray (10YR 6/2) silty clay loam, dark grayish brown (10YR 4/2) moist; moderate thin platy structure; soft, very friable, sticky and plastic; many fine and very fine roots; strongly acid (pH 5.2); clear wavy boundary. (2 to 8 inches thick)
Bw1--5 to 16 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; weak coarse prismatic structure parting to strong fine and very fine subangular blocky; hard, friable, sticky and very plastic; many coarse, medium, fine, and very fine roots; many fine and very fine pores; few very hard shale fragments; very strongly acid (pH 4.6); gradual wavy boundary.
Bw2--16 to 25 inches; grayish brown (2.5Y 5/2) silty clay, dark grayish brown (2.5Y 4/2) moist; moderate fine and very fine subangular blocky structure; hard, friable, sticky and very plastic; common coarse and medium roots; many fine and very fine pores; 10 percent soft shale fragments and 5 percent hard shale fragments; very strongly acid (pH 4.6); diffuse wavy boundary. (combined Bw horizons are 14 to 32 inches thick)
Cr--25 to 60 inches; light brownish gray (2.5Y 6/2) consolidated shale, dark gray (N 4/0 ) moist; brownish yellow (10YR 6/6) coatings on some shale fragments.
TYPE LOCATION: Fergus County, Montana; 2,420 feet south and 1,980 feet east of the NW corner of sec. 4, T. 15 N., R. 23 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 47 degrees F.
Moisture control section - between 4 and 12 inches; dry in all parts between four-tenths and five-tenths of the cumulative days per year when the soil temperature at 20 inches is 41 degrees F or above.
Depth to bedrock - 20 to 40 inches.
A BC horizon is allowed.
E horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1 or 2
Texture: loam or silty clay loam
Clay content: 20 to 40 percent
Reaction: pH 4.5 to 6.5
Bw1 horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1 or 2
Texture: silty clay or clay
Clay content: 40 to 55 percent
Rock fragments: 0 to 15 percent shale fragments--0 to 10 percent soft shale; 0 to 5 percent hard shale
Reaction: pH 3.6 to 5.5
Bw2 horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1 or 2
Texture: silty clay or clay
Clay content: 40 to 50 percent
Rock fragments: 15 to 50 percent shale fragments--10 to 35 percent soft shale; 5 to 15 percent hard shale
Reaction: pH 3.6 to 5.5
Cr horizon semi-consolidated acid shale.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - sedimentary plains; hills.
Elevation - 2,200 to 3,800 feet.
Slope- 4 to 45 percent.
Parent material - residuum derived from semi-consolidated acid shale or in colluvium derived from the shale.
Climate - long winters; moist springs; warm summers.
Mean annual precipitation - 10 to 15 inches.
Mean annual air temperature - 39 to 45 degrees F.
Frost-free period - 115 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dilts, Julin and Teigen soils. Dilts soils are shallow over shale. Julin soils do not have an O horizon. Teigen soils do not have a paralithic contact above a depth of 60 inches and do not have O and E horizons.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Welter soils are used mainly for grazeable woodland. Potential native vegetation is mainly ponderosa pine with an understory of bluebunch wheatgrass and Rocky Mountain juniper.
DISTRIBUTION AND EXTENT: Welter soils are of small extent in central Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Fergus County, Montana, 1979.
REMARKS: Soil interpretations record: MT0335. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 7 inches, mixed (E, Bw1 horizons); a cambic horizon from 4 to 24 inches (Bw1, Bw2 horizons); a particle-size control section from 10 to 24 inches (Bw1, Bw2 horizons). Welter soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.