LOCATION ETHRIDGE MT+ND
Established Series
CJH-GFB-EMM
05/2014
ETHRIDGE SERIES
The Ethridge series consists of very deep, well drained soils that formed in alluvium and glaciofluvial deposits from mixed rock sources, and/or in till and lacustrine deposits. These soils are on alluvial fans, fan remnants, stream terraces, drainageways, hills, sedimentary plains, lake plains, and till plains. Slopes are 0 to 35 percent. Mean annual precipitation is about 305 cm. Mean annual air temperature is about 6.7 degrees C.
TAXONOMIC CLASS: Fine, smectitic, frigid Torrertic Argiustolls
TYPICAL PEDON: Ethridge silty clay loam, in cropland (colors are for dry soil unless otherwise noted).
Ap--0 to 15 cm; grayish brown (2.5Y 5/2) silty clay loam, very dark grayish brown (2.5Y 3/2) moist; strong very fine granular structure; hard, friable, slightly sticky and slightly plastic; few unstained sand grains; neutral (pH 7.0); abrupt smooth boundary. (8 to 18 cm thick)
Bt--15 to 33 cm; brown (10YR 5/3) silty clay, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to strong fine and very fine subangular blocky; very hard, friable, sticky and very plastic; many fine and very fine tubular pores; many distinct very dark grayish brown (10YR 3/2) clay films on peds; neutral (pH 7.0); clear wavy boundary. (13 to 52 cm thick)
Bk--33 to 71 cm; light olive brown (2.5Y 5/3) silty clay loam, olive brown (2.5Y 4/3) moist; strong medium and moderate medium and coarse prismatic structure parting to moderate medium and fine blocky; very hard, friable, sticky and plastic; many fine and very fine tubular pores; few remnants of plate-like varves in lower part; few masses of lime grading to common fine masses of lime in lower part; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (18 to 66 cm thick)
Bky--71 to 124 cm; light brownish gray (2.5Y 6/2) silty clay loam stratified with thin layers of silt loam and silty clay, olive brown (2.5Y 4/3) moist; massive; hard to extremely hard, very friable to firm, sticky and plastic; common very fine pores grading to few very fine pores in the lower part; common fine nests and seams of gypsum; common masses of lime; strongly effervescent; moderately alkaline (pH 8.2); diffuse wavy boundary. (25 to 63 cm thick)
BC--124 to 160 cm; light brownish gray (2.5Y 6/2) stratified with thin layers of loam and silt loam and silty clay loam, light olive brown (2.5Y 5/3) and dark grayish brown (2.5Y 4/2) moist; massive; very hard, very friable, slightly sticky and slightly plastic; few fine gravel and lignite chips; strongly effervescent; moderately alkaline (pH 8.2). (0 to 51 cm)
TYPE LOCATION: Liberty County, Montana; 1,320 feet south and 150 feet east of NW corner of sec. 23, T. 31 N., R. 6 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 5.6 to 8.3 degrees C.
Moisture control section - between 10 and 30 cm; dry in some part for six tenths or more of the cumulative days per year when the soil temperature at a depth of 50 cm is 5 degrees C. or higher.
Mollic epipedon thickness - 18 to 36 cm and may include all or only part of the Bt horizon.
Depth to Bk horizon - 25 to 61 cm.
A Btk horizon is allowed.
Ap horizon
Hue: 10YR or 2.5Y
Value: 2 or 3 moist
Chroma: 2 or 3, dry or moist
Texture: clay loam, loam, silty clay loam, or silt loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 5 percent gravel
Reaction: pH 6.1 to 8.4
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: clay, silty clay, clay loam, or silty clay loam
Clay content: 35 to 45 percent
Rock fragments: 0 to 5 percent gravel
Reaction: pH 6.6 to 8.4
Bk horizon
Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 3, 4, 5, or 6 moist
Chroma: 2, 3, or 4, dry or moist
Texture: clay, silty clay loam, loam, clay loam or silty clay
Clay content: 25 to 45 percent
Rock fragments: 0 to 5 percent gravel
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.4 to 9.0
Bky horizon
Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 3, 4, 5, or 6 moist
Chroma: 2, 3, or 4, dry or moist
Texture: clay loam, silt loam, loam or silty clay loam (these textures consist of strata of finer and coarser materials)
Clay content: 25 to 40 percent
Rock fragments: 0 to 5 percent gravel
Electrical conductivity: 0 to 4 mmhos/cm
Calcium carbonate equivalent: 5 to 15 percent
Gypsum: 1 to 3 percent
Reaction: pH 7.4 to 9.0
In some pedons this horizon may not be stratified or present.
BC or BCy 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
Texture: clay loam, silt loam, or silty clay loam (these textures consist of strata of finer and coarser materials.)
Clay content: 25 to 40 percent
Rock fragments: 0 to 5 percent
Electrical conductivity: 0 to 4 mmhos/cm
Gypsum: 0 to 3 percent
Reaction: pH 7.4 to 9.0
In some pedons this horizon may not be stratified.
COMPETING SERIES:
Dutton (MT) - is 50 to 100 cm deep to a paralithic contact.
Linnet (MT) - has more than 45 percent clay in the Bt horizon.
Patouza (MT) - does not have a Bky horizon.
Sofia (MT) - has more than 50 percent clay in the Bt horizon.
GEOGRAPHIC SETTING:
Landform - alluvial fans, fan remnants, stream terraces, hills, lake plains, till plains, and sedimentary plains.
Elevation - 580 to 1585 meters.
Slope - 0 to 35 percent.
Parent material - alluvium or glaciofluvial deposits from mixed rock sources, and/or in till or lacustrine deposits.
Climate - long, cold winters; moist springs; and hot, dry summers.
Mean annual precipitation - 250 to 355 cm most of which falls during spring and early summer.
Mean annual temperature - 3.9 to 7.7 degrees C.
Frost-free period - 90 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
DRAINAGE AND PERMEABILITY: Well drained; slow permeability.
USE AND VEGETATION: Ethridge soils are used for nonirrigated crops and for range. The potential plant community is green needlegrass, bluebunch wheatgrass, western wheatgrass, forbs, and shrubs.
DISTRIBUTION AND EXTENT: The Ethridge series is extensive in the plains area of Montana and western North Dakota. MLRAs 44B, 46, 52, 58A, 58C, and 60B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Glacier County Area and Part of Pondera County, Montana 1969.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from the soil surface to 15 cm (soil mixed to 18 cm Ap, Bt horizons)
Argillic horizon - from 15 to 33 cm (Bt horizon)
Horizon of lime and gypsum accumulation - from 33 to 124 cm (Bk, Bky horizons)
Particle-size control section - from 15 to 33 cm (Bt horizon).
Soil interpretations record: MT0093.
ADDITIONAL DATA: S68MT-51-3.
National Cooperative Soil Survey
U.S.A.