LOCATION TOLBERT                 MT+CO

Established Series
Rev. DES/CRP/JCK
04/2021

TOLBERT SERIES

The Tolbert series consists of shallow, well drained soils that formed in colluvium or residuum derived from hard fine grained sandstone, fine grained intrusive igneous rock, or interbedded sandstone, siltstone and shale. These soils are on hills, escarpments, dip0slopes, structural benches and mountains. Slopes are 2 to 70 percent. Mean annual precipitation is about 406 mm, and mean annual air temperature is about 4.4 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Lithic Argiustolls

TYPICAL PEDON: Tolbert very cobbly loam, bouldery, in rangeland (colors are for dry soil unless otherwise noted).

A--0 to 18 cm; dark grayish brown (10YR 4/2) very cobbly loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine interstitial pores; 10 percent gravel and 30 percent cobbles; neutral (pH 6.6); clear wavy boundary. (10 to 20 cm thick)

Bt--18 to 30 cm; brown (10YR 5/3) very cobbly clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine and fine interstitial and tubular pores; common distinct dark grayish brown (10YR 4/2) clay films on faces of peds and bridging between sand grains; 15 percent gravel and 40 percent cobbles; neutral (pH 6.8). (13 to 38 cm thick)

R--30 cm; hard fine grained igneous rock.

TYPE LOCATION: Jefferson County, Montana; 91 meters north and 792 meters east of the SW corner of sec. 4, T. 5 N., R. 3 W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 3.3 to 8.0 degrees C
Moisture control section - between 10 and 30 cm or between 10 cm and the lithic contact if bedrock is less than 30 cm; frozen during winter months
Mollic epipedon thickness - 18 to 40 cm
Depth to argillic horizon - 13 to 38 cm
Depth to bedrock - 25 to 50 cm
Surface stones or boulders - 0 to 3 percent
Particle-size control section (weighted average):
Clay content - 18 to 35 percent
Rock fragments - 35 to 80 percent

Some pedons have BA or BC horizons.

A horizon
Hue: 7.5YR, 10YR or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3 dry or moist
Texture: loam or clay loam
Clay content: 15 to 35 percent
Rock fragments: 15 to 80 percent--5 to 65 percent gravel or channers; 0 to 30 percent cobbles; 0 to 25 percent stones
Reaction: pH 6.4 to 7.8

Bt horizon
Hue: 5YR, 7.5YR, 10YR or 2.5Y
Value: 3, 4 or 5 dry; 2, 3 or 4 moist
Chroma: 2, 3, or 4 dry or moist
Texture: loam, clay loam or sandy clay loam
Clay content: 20 to 35 percent
Rock fragments: 35 to 80 percent--15 to 30 percent gravel; 5 to 45 percent cobbles; 0 to 5 percent stones
Reaction: pH 6.6 to 7.8

COMPETING SERIES:
Argirocker (SD) - formed in limestone; have limestone rock fragments
Bushvalley (AZ) formed in breccia, tuff, ash, or cinders; have extrusive igneous rock fragments
Gnojek (MT) - have secondary calcium carbonate accumulation
Owlrock (NM) - have secondary calcium carbonate accumulation; have calcium carbonate equivalent greater than 5 percent throughout
Tolman (WY) - formed in interbedded calcareous sandstone; include moderately alkaline reaction
Zibetod (AZ) - have less than 18 percent clay in the particle-size control section

GEOGRAPHIC SETTING:
Landform - hills, escarpments, dip slopes, structural benches and mountains
Elevation - 1,097 to 2,347 meters (2,682 m in Colorado)
Slope - 2 to 70 percent
Parent material - colluvium or residuum derived from hard fine grained sandstone, fine grained intrusive igneous rock or interbedded sandstone, siltstone, and shale
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 381 to 584 mm
Mean annual air temperature - 2.2 to 7.2 degrees C
Frost-free period - 70 to 115 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Blaincreek, Sawicki, and Shawmut soils.

DRAINAGE AND PERMEABILITY: Well drained, moderate to moderately slow permeability.

USE AND VEGETATION: Tolbert soils are primarily used for rangeland, woodland, and wildlife habitat. Native vegetation is mainly Idaho fescue, rough fescue, bluebunch wheatgrass, sandberg bluegrass, prairie junegrass, lupine, stoneseed, big sagebrush, and Rocky Mountain juniper. Areas in woodland have an overstory of Douglas-fir, limber pine, or ponderosa pine. Native vegetation in Colorado includes Letterman's needlegrass, Geyer's sedge, mountain brome, Gambel oak, snowberry and serviceberry.

DISTRIBUTION AND EXTENT: Tolbert soils are of moderate extent in southwestern Montana and western Colorado. MLRAs 43B, 44B, 46, and 48A.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Powell County Area, Montana, 1995.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 18 cm (A horizon)
Argillic horizon - from 18 to 30 cm (Bt horizon)
Particle size control section - from 0 to 30 cm (A and Bt horizons)
Lithic contact - at 30 cm (R horizon)

Tolbert soils have a frigid temperature regime and an ustic moisture regime.

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National Cooperative Soil Survey
U.S.A.