LOCATION NELDORE MT+WYEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, nonacid, frigid, shallow
Aridic Ustorthents
TYPICAL PEDON: Neldore clay, rangeland (colors are for dry soil unless otherwise noted).
A--0 to 3 inches; grayish brown (2.5Y 5/2) clay, very dark grayish brown (2.5Y 3/2) moist; moderate very fine granular structure; hard, friable, very sticky and very plastic; many medium, fine, and very fine roots; slightly acid (pH 6.2); clear wavy boundary. (2 to 4 inches thick)
C1--3 to 12 inches; grayish brown (2.5Y 5/2) clay, olive gray (5Y 4/2) moist; weak fine and medium subangular blocky structure; very hard, friable, sticky and very plastic; common medium, fine, and very fine roots; many very fine pores; 5 percent hard shale fragments; neutral (pH 6.8); clear wavy boundary. (5 to 10 inches thick)
C2--12 to 18 inches; light gray (5Y 6/1) clay; gray (5Y 5/1) moist; massive; extremely hard, very firm, sticky and very plastic; common coarse, medium, fine, and very fine roots; few very fine pores through shale fragments with most roots between shale chips; 5 percent hard shale fragments; 75 percent soft shale fragments; light brownish gray (2.5Y 6/2) dry and gray and very dark gray (5Y 5/1 and 3/1) moist shale fragments; slightly acid (pH 6.2); gradual wavy boundary. (2 to 7 inches thick)
Cr--18 to 60 inches; gray (5Y 6/1) semiconsolidated shale, gray and very dark gray (5Y 5/1 and 3/1) moist; slightly acid (pH 6.2).
TYPE LOCATION: Fergus County, Montana; 2,000 feet west and 1,700 feet north of the SE corner of sec. 17, T. 21 N., R. 24 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 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 a depth of 20 inches is 41 degrees F or above.
Depth to shale - 10 to 20 inches.
Soil phases - saline.
Dark colors below the A horizon are inherited from the parent shale.
A horizon - Hue: 10YR, 2.5Y, or 5Y
Value: 4, 5, or 6 dry; 3, 4, or 5 moist
Chroma: 1 or 2
Texture: clay, silty clay, silty clay loam, or clay loam
Clay content: 35 to 60 percent
Rock fragments: 0 to 10 percent--0 to 5 percent stones and cobbles, 0 to 5 percent pebbles. The stones, cobbles, and pebbles in some pedons are from a thin glacial mantle that has been eroded away.
EC: less than 4 mmhos/cm; saline phase is 2 to 4 mmhos/cm
Reaction: pH 5.6 to 7.8
C1 horizon - Hue: 10YR, 2.5Y, or 5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1 or 2; 4 or 6 for stains of shale
Texture: clay or silty clay
Structure: strong granular to strong blocky or subangular blocky
Clay content: 40 to 60 percent
Rock fragments: 5 to 35 percent--5 to 25 percent soft shale fragments, 0 to 10 percent hard shale fragments
EC: 0 to 8 mmhos/cm; saline phase is 4 to 8 mmhos/cm
SAR: 15 to 25
Reaction: pH 5.6 through 8.4; saline phase pH 7.4 to 8.4
C2 horizon - Hue: 10YR, 2.5Y, or 5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 1, 2, 3 or 4
Texture: clay or silty clay
Clay content: 40 to 60 percent
EC: 0 to 8 mmhos/cm; saline phase is 4 to 8 mmhos/cm
SAR: 15 to 25
Rock fragments: 65 to 90 percent shale fragments--65 to 75 percent soft shale fragments, 0 to 15 percent hard shale fragments
Gypsum content: 1 to 3 percent
Reaction: pH 5.6 through 8.4; saline phase pH 7.4 to 8.4
Gypsum crystals are few to common at the shale contact and in the lower 1 to 2 inches of the C2 horizon.
Cr horizon - the shale fragments are extremely hard or very hard when dry and extremely firm or very firm when moist
Reaction: pH 5.1 through 7.3.
COMPETING SERIES:
Arsite (MT) - accumulations of gypsum and other salts within 2 inches of the surface; electrical conductivity is greater than 8 mmhos/cm throughout the soil.
GEOGRAPHIC SETTING:
Landform - escarpments; sedimentary plains; hills.
Elevation - 1,900 to 4,000 feet.
Slope- 0 to 70 percent.
Parent material - residuum or colluvium derived from semiconsolidated shale or in clayey alluvium overlying the semiconsolidated shale.
Climate - cool, with moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual air temperature - 40 to 45 degrees F.
Frost-free period - 100 to 135 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Used for rangeland and woodland. The potential native vegetation in rangeland is dominantly bluebunch wheatgrass, western wheatgrass, green needlegrass, prairie sandreed, plains muhly, forbs, and shrubs. In woodland, the overstory is Douglas fir and ponderosa pine, and the understory is Rocky Mountain juniper, chokecherry, rose, western wheatgrass, green needlegrass, prairie sandreed, plains reedgrass, and shrubs.
DISTRIBUTION AND EXTENT: Mainly in central and eastern Montana. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES ESTABLISHED: Fergus County, Montana, 1979.
REMARKS: Soil interpretation records: MT0347, MT0737.
Diagnostic horizons and features recognized in this pedon are: ochric epipedon - from the soil surface to 7 inches (A, C1 horizons); paralithic contact - at a depth of 18 inches (Cr horizon); particle-size control section - from 10 to 18 inches (C1, C2 horizons). Neldore soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
ADDITIONAL DATA: Laboratory data S76MT-087-196.