LOCATION THOENY MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Torrertic Natrustalfs
TYPICAL PEDON: Thoeny loam, grassland (colors are for dry soil unless otherwise noted).
E1--0 to 3 inches; pale brown (10YR 6/3) loam, dark brown (10YR 4/3) moist; weak very fine granular structure; soft, very friable, slightly sticky and nonplastic; many fine roots; many unstained silt and sand grains; neutral (pH 7.2); clear wavy boundary. (2 to 6 inches thick)
E2--3 to 6 inches; light brownish gray (10YR 6/2) loam, dark grayish brown (10YR 4/2) moist; weak medium prismatic structure parting to weak fine granular; soft, very friable, slightly sticky and nonplastic; many fine and very fine roots; many fine pores; many unstained silt and sand grains; mildly alkaline (pH 7.4); abrupt wavy boundary. (1 to 4 inches thick)
Btn1--6 to 9 inches; brown (10YR 5/3) clay, grayish brown (10YR 4/2) moist; strong fine and medium columnar structure parting to weak medium blocky; extremely hard, firm, sticky and very plastic; common fine and very fine roots between peds; common very fine and fine pores; continuous faint dark grayish brown (10YR 4/2) clay films on faces of peds; light gray (10YR 6/1) coats of E horizon material on tops of columns, common faint skeletans of unstained silt and sand grains on vertical faces of peds; mildly alkaline (pH 7.8); clear wavy boundary.
Btn2--9 to 12 inches; brown (10YR 5/3) clay, dark grayish brown (10YR 4/2) moist; strong medium and fine prismatic structure parting to moderate medium blocky; very hard, firm, sticky and very plastic; common fine and very fine roots; common very fine pores; continuous faint dark grayish brown (10YR 4/2) clay film on faces of peds; moderately alkaline (pH 8.2); clear wavy boundary. (Combined Bt1 and Bt2 horizons 7 to 16 inches thick)
Btkn--12 to 17 inches; grayish brown (10YR 5/2) clay loam, dark grayish brown (10YR 4/2) moist; strong medium prismatic structure parting to moderate medium blocky; very hard, firm, sticky and very plastic; common very fine roots; common fine and very fine pores; common faint dark grayish brown (10YR 4/2) clay films on faces of peds; few faint lime coatings on pebbles; strongly effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (0 to 6 inches thick)
Bkn--17 to 28 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to weak medium blocky; very hard, firm, sticky and very plastic; few fine roots; common fine and very fine pores; few faint lime coatings on pebbles; common fine masses and threads of lime; few fine threads of gypsum; strongly effervescent; strongly alkaline (pH 8.8); gradual wavy boundary. (5 to 20 inches thick)
Bkny--28 to 52 inches; grayish brown (2.5Y 5/2) clay loam till, dark grayish brown (2.5Y 4/2) moist; weak medium prismatic and weak medium blocky structure; very hard, friable, sticky and plastic; few very fine roots in upper part; few distinct lime coatings on pebbles; common medium and fine masses of lime; common medium and fine threads and masses of gypsum; strongly effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (10 to 24 inches thick)
By--52 to 60 inches; grayish brown (2.5Y 5/2) clay loam till, dark grayish brown (2.5Y 4/2) moist; weak thick platy structure; very hard, friable, sticky and plastic; slightly effervescent; common fine threads of gypsum; moderately alkaline (pH 8.2).
TYPE LOCATION: Blaine County, Montana; 1,000 feet east and 500 feet south of the NW corner of sec. 29, T. 34 N., R. 20 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - between 4 to 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 higher.
Depth to Bkn horizon - 10 to 32 inches.
A thin 1 to 4 inch A horizon is allowed.
E horizons - Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: loam or clay loam
Clay content: 15 to 40 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles and stones, 0 to 10 percent pebbles
EC: 0 to 4 mmhos/cm
Reaction: pH 5.6 to 7.8
Bt, Btn horizons - Hue: 10YR or 2.5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 or 3
Texture: clay or clay loam
Clay content: 35 to 50 percent
SAR: 5 to 20
EC: 4 to 8 mmhos/cm
Skeletans: unstained sand and silt grains range from very few to common faint on vertical faces of peds
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles and stones, 0 to 10 percent pebbles
Structure: strong to medium, columnar prismatic, or blocky
Reaction: pH 7.4 to 9.0
Btkn, Bkn horizons - Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Texture: clay or clay loam
Clay content: 35 to 50 percent
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles and stones, 0 to 10 percent pebbles
EC: 4 to 8 mmhos/cm
SAR: 13 to 25 or more exchangeable magnesium plus sodium than calcium plus exchange acidity.
Reaction: pH 7.4 to 9.0
Bkny horizon - Hue: 2.5Y or 5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2 or 3
Texture: clay or clay loam
Clay content: 35 to 50 percent
Dry bulk density: 1.55 gr/ccm and greater
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles and stones, 0 to 10 percent pebbles
EC: 4 to 16 mmhos/cm
SAR: 13 to 25 or more exchangeable magnesium plus sodium than calcium plus exchange acidity
Gypsum: 1 to 3 percent
Reaction: pH 7.9 to 9.0
By horizon - Hue: 2.5Y or 5Y
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 or 3
Clay content: 27 to 40 percent
Dry bulk density: 1.55 gr/ccm and greater
Rock fragments: 0 to 15 percent--0 to 5 percent cobbles and stones, 0 to 10 percent pebbles
EC: 4 to 16 mmhos/cm
Gypsum: 1 to 6 percent
Reaction: pH 7.4 to 9.0
COMPETING SERIES:
Absher (MT) - has a combined thickness of the A and E horizons of 1/4 inch to 6 inches; electrical conductivity of 8 to 16 in the natric horizons that are above a depth of 28 inches.
Creed (MT) - no till with a bulk density of 1.55 and greater above a depth of 40 inches.
Elloam (MT) - crusty surface layer; E horizons that are 4 inches or less thick; gypsum below a depth of 22 inches.
Gerdrum (MT) - did not form in till that has a bulk density of 1.55 and greater.
Oburn (MT) - loamy-skeletal C horizon at depths of 20 to 40 inches.
Weingart (MT) - paralithic contact at a depth of 20 to 40 inches.
GEOGRAPHIC SETTING:
Landform - till plains.
Elevation - 1,900 to 3,800 feet.
Slope- 0 to 8 percent.
Parent material - pre-Wisconsin till.
Climate - long, cold winters; 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 130 days.
DRAINAGE AND PERMEABILITY: Well drained; very slow permeability.
USE AND VEGETATION: Thoeny soils are used mainly for dryland farming and rangeland. Potential native vegetation is mainly western wheatgrass, needleandthread, prairie junegrass, green needlegrass, blue grama, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Thoeny soils are of moderate extent on the till plains of northern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: St. Paul, Minnesota
SERIES ESTABLISHED: Valley County, Montana, 1976.
REMARKS: Soil interpretations record: MT0236. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 6 inches (E1, E2 horizons); an argillic horizon from 6 to 12 inches which is also the particle-size control section (Bt1, Bt2 horizons); a natric horizon from 12 to 22 inches (Btkn, part of Bkn horizons); horizons of secondary carbonate accumulation from 12 to 52 inches (Btkn, Bkn, Bkny horizons).
ADDITIONAL DATA: Laboratory sample S62MT-5-13; S90MT-071-010.