LOCATION THESS MT
Established Series
Rev. GFB-JJU-RJS
06/2011
THESS SERIES
The Thess series consists of very deep, well drained soils that formed in alluvium. These soils are on alluvial fans, fan remnants, stream terraces and basin floors. Slopes are 0 to 8 percent. Mean annual precipitation is about 12 inches, and mean annual air temperature is about 42 degrees F.
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Aridic Calciustepts
TYPICAL PEDON: Thess loam, native grass (colors are for dry soil unless otherwise noted).
A--0 to 5 inches; pinkish gray (7.5YR 6/2) loam, brown (7.5YR 4/2) moist; strong fine platy structure; soft, very friable, slightly sticky and slightly plastic; many fine roots; common fine pores; finely disseminated calcium carbonate; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (3 to 5 inches thick)
Bk1--5 to 22 inches; light gray (10YR 7/2) loam, brown (10YR 5/3) moist; weak coarse prismatic structure; slightly hard, very friable, slightly sticky and slightly plastic; common fine roots, common fine pores; 5 percent gravel, 5 percent cobbles; finely disseminated calcium carbonate and continuous distinct calcium carbonate coatings on surface of rock fragments; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (10 to 24 inches thick)
Bk2--22 to 34 inches; very pale brown (10YR 7/3) loam, consisting of thin strata of silt loam and sandy loam brown (10YR 5/3) moist; massive; slightly hard, very friable, slightly sticky and nonplastic; few fine roots; 5 percent gravel and 5 percent cobbles; finely disseminated calcium carbonate and continuous distinct calcium carbonate coatings on surface of rock fragments; strongly effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (0 to 20 inches thick)
2Bk3--34 to 60 inches; very gravelly sand; variegated colors; single grain; loose, nonsticky and nonplastic; 50 percent gravel and 20 percent cobbles; finely disseminated calcium carbonate and continuous faint calcium carbonate casts on undersides of rock fragments; slightly effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Broadwater County, Montana; 100 feet north and 50 feet east of the southwest corner of sec. 7, T. 5N, R. 2E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 40 to 47 degrees F.
Depth to calcic horizon - 3 to 5 inches
Depth to lithologic discontinuity - 20 to 35 inches
A horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 5 or 6 dry; 3 to 5 moist
Chroma: 2 or 3; dry or moist
Texture: loam, sandy loam or silt loam
Clay content: 15 to 25 percent
Rock fragments: 0 to 45 percent--0 to 25 percent gravel, 0 to 20 percent cobbles and stones
Calcium carbonate equivalent: 1 to 10 percent
Reaction: pH 7.4 to 8.4
Bk1 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 to 8 dry; 4 to 7 moist
Chroma: 2 or 3; dry or moist
Texture: loam, silt loam or sandy loam
Clay content: 15 to 25 percent
Rock fragments: 0 to 25 percent--0 to 20 percent gravel, 0 to 5 percent cobbles and stones
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 7.4 to 8.4
Bk2 horizon
Hue: 10YR or 2.5Y; dry or moist
Value: 6 to 8 dry; 5 to 7 moist
Chroma: 2 or 3; dry or moist
Texture: loam, silt loam or sandy loam consisting of thin stratification
Clay content: 15 to 25 percent
Rock fragments: 0 to 15 percent--0 to 10 percent gravel, 0 to 5 percent cobbles and stones
Calcium carbonate equivalent: 15 to 40 percent
Reaction: pH 7.4 to 8.4
2Bk horizon
Hue: 10YR or 2.5Y; dry or moist (colors are variegated)
Value: 5 to 8 dry; 4 to 7 moist
Chroma: 2 or 4; dry or moist
Texture: sand or loamy sand
Clay content: 0 to 5 percent
Rock fragments: 35 to 85 percent--35 to 60 percent gravel, 0 to 25 percent cobbles and stones
Calcium carbonate equivalent: 15 to 25 percent
Reaction: pH 7.4 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - alluvial fans, fan remnants, stream terraces and basin floors
Elevation - 3,500 to 6,700 feet
Slope - 0 to 8 percent
Parent material - alluvium
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 10 to 14 inches
Mean annual 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 to 34 inches and very rapid below.
USE AND VEGETATION: Thess soils are used mainly for irrigated hayland and grain, or dryland grain, and range. Potential native vegetation is mainly blue grama, Sandberg bluegrass, prairie junegrass, western wheatgrass, needleandthread, fringed sagewort, broom snakeweed, and pricklypear cactus.
DISTRIBUTION AND EXTENT: Thess soils are moderately extensive in central Montana. MLRAs - 43B, 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Broadwater County Area, Montana, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from 0 to 5 inches (A horizon)
Calcic horizon - from 5 to 60 inches (Bk1, Bk2, 2Bk3 horizons)
Lithologic discontinuity - at 34 inches (2Bk3 horizon)
Particle-size control section - from 10 to 40 inches (part of Bk1, Bk2, part of 2Bk2 horizons)
Thess soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.
ADDITIONAL DATA: Soil interpretations records - MT0511, MT0790.
National Cooperative Soil Survey
U.S.A.