LOCATION LEDGER MTEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, calcareous, frigid Oxyaquic Ustifluvents
TYPICAL PEDON: Ledger silty clay loam, in pasture (Colors are for dry soil unless otherwise noted).
Az1--0 to 3 inches; light brownish gray (10YR 6/2) silty clay loam, brown (10YR 4/3) moist; moderate fine and 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; disseminated lime; common very fine masses of salt; strongly effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary.
Az2--3 to 7 inches; light brownish gray (10YR 6/2) silty clay loam, brown (10YR 4/3) moist; moderate fine and medium platy structure; slightly hard, very friable, moderately sticky and moderately plastic; many very fine and fine and few medium roots; many very fine and fine and few medium tubular pores; disseminated lime; common very fine and fine masses and threads of salt; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (Combined thickness of A horizons is 4 to 7 inches).
Cz1--7 to 16 inches; light gray (10YR 7/2) silty clay loam, grayish brown (10YR 5/2) moist; moderate coarse platy structure parting to moderate medium subangular blocky; slightly hard, very friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine and fine interstitial and tubular pores; disseminated lime; few very fine masses of salt; strongly effervescent; strongly alkaline (pH 9.0); clear wavy boundary.
Cz2--16 to 25 inches; gray (10YR 5/1) silty clay loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; common very fine and fine interstitial and tubular pores; disseminated lime; common very fine and fine masses and threads of salt; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (Combined thickness of Cz horizons is 10 to 25 inches).
Ckzg1--25 to 34 inches; grayish brown (10YR 5/2) silty clay loam, dark gray (10YR 4/1) moist; common faint very dark gray (5Y 3/1) redox depletions; few faint strong brown (7.5YR 5/6) redox concentrations; moderate fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine roots; common very fine interstitial and tubular pores; disseminated lime; few very fine masses and threads of lime; common very fine and fine masses and threads of salt; strongly effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (0 to 12 inches thick)
Ckzg2--34 to 60 inches; light brownish gray (10YR 6/2) silty clay loam, dark grayish brown (10YR 4/2) moist; common faint dark gray (5Y 4/1) redox depletions; massive; very hard, very firm, moderately sticky and moderately plastic; few very fine roots; disseminated lime; few fine and medium masses and threads of lime; common fine masses and threads of salt; slightly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Jefferson County, Montana; 2,100 feet south and 2,600 feet east of the northwest corner of sec. 33, T. 2 N., R. 4 W.
RANGE IN CHARACTERISTICS:
Soil Temperature - 42 to 46 degrees F.
Moisture control section - between 4 and 12 inches.
Depth to seasonal high water table - 24 to 42 inches for extended periods during spring and early summer.
The surface layer, when mixed to 7 inches, does not meet color requirements for a mollic epipedon. A thin surface crust is allowed.
This soil has an irregular decrease of organic carbon with depth.
Az horizons - Hue: 10YR or 2.5Y
Value: 4, 5 or 6 dry; 2, 3 or 4 moist
Chroma: 1, 2, 3 or 4
Texture: silt loam, clay loam or silty clay loam
Clay content: 15 to 40 percent
Electrical conductivity: 8 to 20 mmhos/cm
Sodium absorption ratio: greater than 13
Calcium carbonate equivalent: 3 to 10 percent
Reaction: pH 7.9 to 10.0
Cz1 horizon - Hue: 10YR or 2.5Y
Value: 5, 6 or 7 dry; 4 or 5 moist
Chroma: 1, 2 or 3
Texture: silty clay loam, clay loam or clay
Clay content: 35 to 45 percent
Electrical conductivity: 8 to 20 mmhos/cm
Sodium absorption ratio: greater than 13
Calcium carbonate equivalent: 10 to 20 percent
Reaction: pH 7.9 to 10.0
Cz2 horizon - Hue: 10YR, 2.5Y or 5Y
Value: 4, 5, 6 or 7 dry; 3, 4 or 5 moist
Chroma: 1 or 2
Texture: silty clay loam and clay loam with thin strata of loamy very fine sand, loam, or silt loam
Clay content (weighted average): 35 to 45 percent
Electrical conductivity: 8 to 16 mmhos/cm
Sodium absorption ratio: greater than 13
Calcium carbonate equivalent: 10 to 20 percent
Reaction: pH 7.9 to 9.6
Ckzg1 horizon - Hue: 10YR, 2.5Y or 5Y
Value: 4, 5, 6 or 7 dry; 3, 4 or 5 moist
Chroma: 1 or 2
Redox concentration: few to common 7.5YR 5/6 or 5YR 5/6
Redox depletions: few to common 10YR 3/1, 10YR 4/1 and 5Y 4/1
Texture: silty clay loam, clay loam and clay consisting of thin strata of loamy very fine sand, loam or silt loam
Clay content (weighted average): 35 to 45 percent
Electrical conductivity: 8 to 16 mmhos/cm
Sodium absorption ratio: greater than 13
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.9 to 10.0
Ckzg2 horizon - Hue: 10YR, 2.5Y or 5Y
Value: 4, 5, 6 or 7 dry; 3, 4 or 5 moist
Chroma: 1 or 2
Redox concentration: none to common 7.5YR 5/6 or 5YR 5/6
Redox depletions: few to many 10YR 3/1, 10YR 4/1) and 5Y 4/1
Texture: loam, silty clay loam, clay loam, silt loam with thin strata of coarser and finer materials
Clay content (weighted average): 25 to 40 percent
Rock fragments: 0 to 20 percent pebbles
Electrical conductivity: 8 to 16 mmhos/cm
Sodium absorption ratio: greater than 13
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.9 to 10.0
COMPETING SERIES:
There are no competing series.
GEOGRAPHIC SETTING:
Landform - flood plains, flood plain steps and drainageways.
Elevation - 3,800 to 5,400 feet.
Slope- 0 to 2 percent.
Parent material - saline and sodic alluvium derived from mixed rock sources.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 10 to 14 inches.
Mean annual air temperature - 40 to 44 degrees F.
Frost-free period - 90 to 115 days.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained, very slow permeability.
USE AND VEGETATION: Ledger soils are primarily used for rangeland and pasture. The potential native vegetation is mainly alkali sacaton, Western wheatgrass, Inland saltgrass, foxtail, bluegrass, basin wildrye and greasewood.
DISTRIBUTION AND EXTENT: Ledger soils are of small extent in the intermountain valleys of southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretation record: MT1571. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the surface to 7 inches mixed (Az1 and Az2 horizons); an accumulation of salt and sodium from the surface to 60 inches (all horizons); a particle size control section from 10 to 40 inches (Cz1, Cz2, Ckzg1 and Ckzg2 horizons). Ledger soils have a frigid temperature regime and an ustic moisture regime bordering on aquic.