LOCATION GNOJEK MT
Established Series
Rev. DES-JAL-EMM
11/2012
GNOJEK SERIES
The Gnojek series consists of shallow, well drained soils that formed in colluvium or residuum derived from hard fine grained sandstone or fine grained igneous rock. These soils are on escarpments, ridges and hills. Slopes are 2 to 70 percent. Mean annual precipitation is about 16 inches, and mean annual air temperature is about 40 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Lithic Argiustolls
TYPICAL PEDON: Gnojek very cobbly loam, stony, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 3 inches; dark grayish brown (10YR 4/2) very cobbly loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and nonplastic; many very fine and fine roots; many very fine and fine interstitial pores; 25 percent cobbles and 20 percent gravel; neutral (pH 7.2); clear wavy boundary. (3 to 7 inches thick)
Bt--3 to 7 inches; dark grayish brown (10YR 4/2) very gravelly clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium prismatic structure parting to moderate fine subangular blocky; slightly hard, firm, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine interstitial and tubular pores; common distinct clay films on faces of peds and bridging sand grains; 15 percent cobbles and 35 percent gravel; slightly alkaline (pH 7.4); clear wavy boundary. (4 to 9 inches thick)
Bk--7 to 16 inches; light brownish gray (10YR 6/2) very cobbly loam, brown (10YR 5/3) moist; moderate fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine interstitial and tubular pores; 25 percent cobbles and 30 percent gravel; disseminated lime; common medium masses and threads of lime; common distinct lime coatings on fragments; violently effervescent; moderately alkaline (pH 8.2).
R--16 inches; hard fine grained sandstone.
TYPE LOCATION: Jefferson County, Montana; 40 feet north and 50 feet west of the SE corner of sec. 22, T. 3 N., R. 4 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 38 to 44 degrees F.
Moisture control section - between 4 and 12 inches or between 4 inches and the lithic contact when bedrock is less than 12 inches; is frozen during winter months.
Mollic epipedon thickness - 7 to 10 inches.
Depth to argillic horizon - 3 to 7 inches.
Depth to the Bk horizon - 7 to 16 inches.
Depth to bedrock - 10 to 20 inches.
Surfaces stones or boulders - 0 to 0.1 percent.
A horizon
Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3, dry or moist
Clay content: 15 to 27 percent
Rock fragments: 35 to 50 percent total--10 to 25 percent cobbles or flagstones and 20 to 25 percent gravel
Reaction: pH 6.6 to 7.4
Bt horizon
Hue: 10YR or 2.5Y
Value: 4, 5, or 6 dry; 3, 4, or 5 moist
Chroma: 2, 3, or 4, dry or moist
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 35 to 80 percent total--0 to 15 percent stones, 15 to 35 percent cobbles, and 20 to 40 percent gravel
Reaction: pH 6.6 to 7.8
Bk horizon
Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4, dry or moist
Clay content: 18 to 27 percent
Rock fragments: 35 to 80 percent total--0 to 15 percent stones, 10 to 35 percent cobbles and 20 to 40 percent gravel
Calcium carbonate equivalent: 10 to 25 percent
Reaction: pH 7.4 to 8.4
Btk horizon present in some pedons.
COMPETING SERIES:
Argirocker (SD) - does not have a horizon of secondary carbonate accumulation.
Bushvalley (AZ) - does not have a horizon of secondary carbonate accumulation.
Owlrock (NM) - formed in limestone at elevations greater than 7200 feet.
Tolbert (MT) - does not have a horizon of secondary carbonate accumulation.
Tolman (WY) - does not have a horizon with secondary carbonate accumulation.
Zibetod() - does not have a horizon with secondary carbonate accumulation.
GEOGRAPHIC SETTING:
Landform - escarpments, ridges and hills.
Elevation - 3,900 to 6,000 feet.
Slope - 2 to 70 percent.
Parent material - colluvium or residuum derived from hard fine grained sandstone or fine grained igneous rock.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual air temperature - 38 to 45 degrees F.
Frost-free period - 70 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Gnojek soils are primarily used for rangeland and wildlife habitat. The potential native vegetation is mainly bluebunch wheatgrass, Idaho fescue, sandberg bluegrass, prairie junegrass needleandthread, yarrow, big sagebrush, rubber rabbitbrush, and Rocky Mountain juniper. Some areas have widely scattered Douglas fir and limber pine.
DISTRIBUTION AND EXTENT: Gnojek soils are of moderate extent in southwestern Montana. MLRA 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretation record: MT3050.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface to 7 inches (A, Bt horizons);
Argillic horizon - the zone from 3 to 7 inches (Bt horizon);
Particle-size control section - the zone from the top of the argillic horizon to 16 inches (Bt, Bk horizons);
Horizon of secondary calcium carbonate accumulation - the zone from 7 to 16 inches (Bk horizon);
Lithic contact - hard fine grained sandstone bedrock at 16 inches (R horizon).
Gnojek soils have a frigid temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.