LOCATION ROMNOT MT
Established Series
Rev: GFB-JJU-RJS
01/2012
ROMNOT SERIES
The Romnot series consists of very deep, well drained soils that formed in alluvium. These soils occur on stream terraces, fan remnants and drainageways. Slopes are 0 to 4 percent. Mean annual precipitation is about 300 mm, and mean annual air temperature is about 5 degrees C.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Aridic Leptic Natrustalfs
TYPICAL PEDON: Romnot silt loam, in rangeland (colors are for dry soil unless otherwise noted).
A--0 to 8 cm; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine dendritic tubular pores; moderately alkaline (pH 8.2); clear smooth boundary. (0 to 10 cm thick)
E--8 to 18 cm; light brownish gray (10YR 6/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; moderate thin platy structure; slightly hard, very friable, nonsticky and nonplastic; many very fine and fine roots; many very fine and common fine irregular pores; strongly alkaline (pH 8.8); abrupt smooth boundary. (5 to 13 cm thick)
Btn--18 to 38 cm; light brownish gray (10YR 6/2) silty clay loam, brown (10YR 4/3) moist; strong medium columnar structure parting to strong medium subangular blocky, very hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; many very fine tubular pores; 35 percent faint clay films on all faces of peds; finely disseminated calcium carbonate; strongly effervescent; very strongly alkaline (pH 9.6); clear wavy boundary. (10 to 25 cm thick)
Btkny--38 to 64 cm; yellowish brown (10YR 5/4) loam, dark brown (10YR 3/3) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common fine roots; many fine tubular pores; 35 percent faint clay films on all faces of peds; 1 percent fine gypsum crystals; finely disseminated calcium carbonate and 5 percent fine, distinct, irregular, soft masses of calcium carbonate; violently effervescent; very strongly alkaline (pH 9.6); gradual wavy boundary. (10 to 38 cm thick)
Bkyz--64 to 102 cm; yellowish brown (10YR 5/4) loam, dark brown (10YR 3/3) moist; moderate coarse prismatic structure parting to moderate medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common fine roots; common fine tubular pores; 5 percent gravel; 10 percent fine and medium gypsum crystals; finely disseminated calcium carbonate and 5 percent fine, distinct, irregular, soft masses of calcium carbonate; violently effervescent; very strongly alkaline (pH 9.6); gradual wavy boundary. (10 to 38 cm thick)
BCyz--102 to 152 cm; brown (10YR 5/3) sandy loam, dark brown (10YR 3/3) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine roots; 10 percent gravel; 1 percent fine gypsum crystals; finely disseminated calcium carbonate; strongly effervescent; very strongly alkaline (pH 9.2); gradual wavy boundary.
TYPE LOCATION: Beaverhead County, Montana; located about 1,200 feet north and 100 feet west of the southeast corner of sec. 25, T. 9S, R. 14W; Coyote Creek topographic quadrangle; UTM 12T, 320785e, 4987743n, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 7 degrees C.
Particle-size control section (weighted average) - 25 to 35 percent clay
Depth to natric horizon - 5 to 20 cm
Note: Where irrigated some pedons may have an Oi horizon.
A horizon
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: silt loam or loam
Clay content: 15 to 25 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 0 to 5 percent
Sodium adsorption ratio: 5 to 15
Electrical conductivity: 0 to 3 mmhos/cm
Reaction: pH 7.9 to 8.6
E horizon
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2 or 3; dry or moist
Texture: fine sandy loam, silt loam or loam
Clay content: 15 to 25 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 0 to 5 percent
Sodium adsorption ratio: 13 to 40
Electrical conductivity: 0 to 4 mmhos/cm
Reaction: pH 8.5 to 10.0
Btn horizon
Value: 5 or 6 dry; 3 or 4 moist
Chroma: 2 or 3; dry or moist
Texture: silty clay loam or clay loam
Clay content: 27 to 40 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 0 to 5 percent
Sodium adsorption ratio: 40 to 100
Electrical conductivity: 4 to 8 mmhos/cm
Reaction: pH 9.0 to 10.5
Btkny horizon
Value: 5 or 6 dry; 3 to 5 moist
Chroma: 2 to 4; dry or moist
Texture: loam, clay loam or silty clay loam
Clay content: 24 to 35 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 1 to 10 percent
Sodium adsorption ratio: 40 to 100
Gypsum: 1 to 3 percent
Electrical conductivity: 4 to 8 mmhos/cm
Reaction: pH 9.0 to 10.5
Bkyz horizons
Value: 5 or 6 dry; 3 to 5 moist
Chroma: 2 to 4; dry or moist
Texture: sandy loam, loam or sandy clay loam
Clay content: 15 to 25 percent
Rock fragments: 0 to 15 percent gravel
Calcium carbonate equivalent: 1 to 10 percent
Sodium adsorption ratio: 20 to 60
Gypsum: 1 to 3 percent
Electrical conductivity: 2 to 8 mmhos/cm
Reaction: pH 9.0 to 10.5
BCyz horizon
Value: 5 or 6 dry; 3 to 5 moist
Chroma: 2 to 4; dry or moist
Texture: sandy loam, loam or sandy clay loam
Clay content: 15 to 25 percent
Rock fragments: 0 to 35 percent gravel
Calcium carbonate equivalent: 1 to 10 percent
Sodium adsorption ratio: 20 to 60
Gypsum: 1 to 3 percent
Electrical conductivity: 1 to 4 mmhos/cm
Reaction: pH 9.0 to 10.5
COMPETING SERIES:
Bullock (MT) - are moderately deep to a paralithic contact
Rominell (MT) - do not have secondary calcium carbonate accumulation
GEOGRAPHIC SETTING:
Landform - stream terraces, fan remnants and drainageways
Elevation - 1790 to 2025 meters
Slope - 0 to 4 percent
Parent material - alluvium
Climate - long, cold winters; cool, moist springs; short, cool summers
Mean annual precipitation - 230 to 360 mm
Mean annual air temperature - 4 to 7 degrees C.
Frost-free period - 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Romnot soils are used for rangeland and wildlife habitat. The vegetation is mainly basin wildrye, POA (species), thickspike wheatgrass, western wheatgrass, inland saltgrass, big sagebush (species) and greasewood.
DISTRIBUTION AND EXTENT: Romnot soils are of small extent in southwestern Montana. MLRA - 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Horse Prairie-South Valley Area - Part of Beaverhead County, Montana, 2011; proposed in Beaverhead County, Montana, 2008.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from 0 to 18 cm (A, E horizons)
Albic horizon - from 8 to 18 cm (E horizon)
Natric horizon - from 18 to 64 cm (Btn, Btkny horizons)
Accumulations of gypsum and other soluble salts - from 64 to 152 cm (Btkny, Bkyz, BCyz)
Particle-size control section - from 18 to 64 cm (Btn, Btkny horizons)
Romnot soils have a frigid temperature regime and an ustic moisture regime bordering on aridic.
National Cooperative Soil Survey
U.S.A.