LOCATION VOLBORG MTEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, acid, frigid, shallow Aridic Ustorthents
TYPICAL PEDON: Volborg silty clay, in grassland. (Colors are for dry soil unless otherwise noted)
A--0 to 3 inches; grayish brown (10YR 5/2) silty clay, brown (10YR 4/3) moist; moderate very fine granular structure with weak, thin crust at surface; soft, very friable, sticky and very plastic; common very fine roots; moderately acid (pH 6.0); abrupt smooth boundary. (0 to 4 inches thick)
C--3 to 15 inches; grayish brown (10YR 5/2) silty clay, brown (10YR 4/3) moist; moderate very fine granular structure; hard, friable, sticky and very plastic; common very fine roots; common very fine pores; very strongly acid (pH 4.8); clear wavy boundary. (8 to 16 inches thick)
Cr--15 to 60 inches; gray (10YR 6/1) semiconsolidated shale, dark gray (10YR 4/1) moist; common very fine roots matted at top of shale and in cracks in upper 4 inches; common reddish brown (5YR 4/4) iron stains on shale fragments; common pale yellow (5Y 8/4) sulfur bands; extremely acid (pH 4.4).
TYPE LOCATION: Rosebud County, Montana; 200 feet north and 25 feet east of the SW corner of sec. 19, T. 8 N., R. 40 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 41 to 47 degrees F.
Moisture control section - between 4 to 12 inches thick, dry in all parts between four-tenths and five-tenths of the cumulative days per year when the temperature at a depth of 20 inches is 41 degrees F or higher.
Depth to bedrock - 10 to 20 inches; in the saline phase it is 10 to 14 inches.
Soil phases - saline.
The dark colors in this soil are lithochromic of the parent material. In pedons which are less than 14 inches to the consolidated shale, the pH is 5.5 or less.
A horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1 to 3
Texture: silty clay loam, silty clay or clay
Clay content: 35 to 50 percent
EC: less than 4 mmhos/cm
SAR: 0 to 13; 5 to 13 in saline phase
Reaction: pH 4.5 to 6.5
C horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1 to 3
Texture: silty clay loam, silty clay or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 80 percent--0 to 30 percent soft fragments; 30 to 80 percent soft fragments in saline phase
EC: 2 to 16 mmhos/cm; 8 to 16 mmhos/cm in saline phase
SAR: 0 to 13
Reaction: pH 3.6 to 5.5
Some pedons have very fine blocky structure. Salinity is from the shale fragments and is not due to illuviation of salts.
Cr horizon - semiconsolidated shale
EC: 8 to 16 mmhos/cm
Reaction: pH 3.6 to 5.5
Iron and sulfur bands are common to many pedons.
COMPETING SERIES:
Dilts (ND) - has a C horizon which is very hard or extremely hard when dry and very firm or extremely firm when moist; has weak coarse subangular blocky structure that parts to platy.
GEOGRAPHIC SETTING:
Landform - sedimentary plains; hills; ridges.
Elevation - 2,200 to 5,200 feet.
Slope- 1 to 60 percent.
Parent material - residuum from semiconsolidated shale.
Climate - cool with long, cold, dry winters; moist springs; and warm summers.
Mean annual precipitation - 10 to 16 inches.
Mean annual temperature - 39 to 45 degrees F.
Frost-free period - 100 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Volborg soils are used for rangeland. The potential native vegetation is prairie sandreed, western wheatgrass, sun sedge, shrubs and forbs. The potential native vegetation on the eroded phase is mainly western wheatgrass, Montana wheatgrass, prairie sandreed, Nuttall saltbush, slender eriogonum, sagebrush and rubber rabbitbrush.
DISTRIBUTION AND EXTENT: Southeastern Montana. These soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Rosebud County, Montana, 1990.
REMARKS: Soil interpretations records: MT0351 and MT0894.
Diagnostic horizons and features recognized in the pedon are: ochric epipedon - from the soil surface to 7 inches, mixed (A, part of C horizon); paralithic contact - at 15 inches (C horizon). Neldore soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
Additional Data: Laboratory sample S90MT-071-001.