LOCATION NIART MTEstablished Series
TAXONOMIC CLASS: Fine-loamy, carbonatic, frigid Aridic Calciustolls
TYPICAL PEDON: Niart loam, cultivated (colors are for dry soil unless otherwise noted).
Ap--0 to 6 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; moderate coarse granular structure parting to weak fine granular; slightly hard, very friable, moderately sticky and slightly plastic; common fine roots; many fine irregular pores; about 5 percent pebbles; slightly effervescent; moderately alkaline (pH 8.0); abrupt clear boundary. (6 to 10 inches thick)
Bw--6 to 10 inches; light brownish gray (10YR 6/2) clay loam, dark grayish brown (10YR 4/2) moist; weak coarse prismatic structure parting to moderate medium blocky; hard, very friable, moderately sticky and moderately plastic; common fine roots; common fine and medium pores; about 10 percent pebbles; disseminated lime; strongly effervescent; moderately alkaline (pH 8.2); gradual clear boundary. (0 to 5 inches thick)
Bk1--10 to 19 inches; light brownish gray (10YR 6/2) clay loam, grayish brown (10YR 5/2) moist; weak medium prismatic structure parting to moderate medium subangular blocky; hard, very friable, moderately sticky and moderately plastic; common fine roots; common fine pores; 10 percent pebbles with lime coats on undersides; disseminated lime; violently effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (5 to 14 inches thick)
Bk2--19 to 30 inches; light gray (2.5Y 7/2) clay loam, light brownish gray (2.5Y 6/2) moist; weak coarse prismatic structure parting to moderate fine and medium subangular blocky; hard, friable, moderately sticky and moderately plastic; few very fine roots; many very fine vesicular pores; 5 percent pebbles with lime crusts on undersides; many medium and coarse masses of lime; violently effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (8 to 15 inches thick)
2Bk3--30 to 60 inches; pale yellow (2.5Y 8/2) very gravelly loam, light brownish gray (2.5Y 6/2) moist; massive; hard, friable, moderately sticky and moderately plastic; 55 percent pebbles with continuous distinct lime coating on surface of pebbles and continuous prominent lime crusts on underside of pebbles; violently effervescent; moderately alkaline (pH 8.4).
TYPE LOCATION: Teton County, Montana; 2,600 feet east and 1,000 feet north of the SW corner of Sec. 20, T. 22 N., R. 2 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 47 degrees F.
Moisture control section - moist in some part in most years more than half the time from April through October. These soils are in the ustic moisture regime intergrading to the aridic moisture regime.
Mollic epipedon thickness - 7 to 10 inches.
Control section - 18 to 32 percent noncarbonate clay.
Depth to Bk1 horizon - 6 to 17 inches.
Depth to 2Bk2 horizon - 19 to 40 inches.
Ap horizon - Hue: 10YR or 2.5Y
Value: 4 or 5 dry; 3 moist
Chroma: 2 or 3
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 5 to 45 percent--0 to 5 percent cobbles, 5 to 40 percent pebbles
Reaction: pH 7.4 to 8.4
Bw horizon - Hue: 10YR or 2.5Y
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 3 or 4
Texture: loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 5 to 35 percent--0 to 10 percent cobbles and stones, 5 to 25 percent pebbles
Reaction: pH 7.8 to 8.4
Bk1 and Bk2 horizons - Hue: 10YR or 2.5Y
Value: 6, 7, or 8 dry; 5, 6, or 7 moist
Chroma: 2, 3, or 4
Texture: loam or clay loam
Clay content: 25 to 35 percent (20 to 30 percent noncarbonate clay)
Rock fragments: 5 to 30 percent--0 to 5 percent cobbles, 5 to 25 percent pebbles
Calcium carbonate equivalent: 40 to 55 percent
Reaction: pH 7.9 to 9.0
2Bk3 horizon - Hue: 10YR or 2.5Y
Value: 6, 7, or 8 dry; 5, 6, or 7 moist
Chroma: 2 or 4
Texture: loam, sandy clay loam, or sandy loam
Clay content: 20 to 30 percent (10 to 25 percent noncarbonate clay)
Rock fragments: 35 to 80 percent--5 to 10 percent cobbles, 30 to 70 percent pebbles
Calcium carbonate equivalent: 45 to 55 percent
Reaction: pH 7.9 to 9.0
COMPETING SERIES:
Ninot (CO) - does not have a loamy-skeletal horizon above 40 inches.
GEOGRAPHIC SETTING: Niart soils are on dissected alluvial fans, stream terraces, mountains, and hills. Elevations are 3,200 to 5,000 feet. Slopes are 0 to 45 percent. Niart soils formed in colluvium and alluvium derived mainly from limestone and calcareous sandstone. The climate is characterized by long, cold winters; moist springs; and warm summers. Mean annual precipitation is 10 to 14 inches. Mean annual temperature is 39 to 45 degrees F. The frost-free period is 105 to 125 days. In Colorado elevations are 6,800 to 8,100 feet, the frost-free period is 75 to 95 days, and the mean annual precipitation ranges to 15 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Niart soils are used mainly for dryland and irrigated crops; some small areas are used for rangeland. Potential native vegetation is mainly western wheatgrass, bluebunch wheatgrass, prairie junegrass, needleandthread, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Niart soils are of moderate extent in north-central Montana. MLRAs 34A, 46 and 58A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Choteau-Conrad Area, Montana, 1990; proposed in Cascade County, Montana, 1966.
REMARKS: Soil interpretations record: MT0596, MT0878, MT0764. Diagnostic horizons and features recognized in this pedon are: a mollic epipedon from the soil surface to 7 inches (Ap and part of the Bw horizon); a cambic horizon from 6 to 19 inches (Bw and Bk1 horizons); horizons of lime accumulation from 19 to 60 inches (Bk1, Bk2, and 2Bk3 horizons); a calcic horizon from 10 to 60 inches (Bk1, Bk2, and 2Bk3 horizons); a particle-size control section from 10 to 40 inches (Bk1, Bk2, and 2Bk3 horizons). Niart soils have a frigid temperature regime and an ustic moisture regime that borders on aridic.