LOCATION MIDNOT MT
Tentative Series
Rev. CCF-JCK
05/2014
MIDNOT SERIES
The Midnot series consists of moderately deep, well drained soils that formed in alluvium or colluvium over residuum from semi-consolidated shale, siltstone or mudstone. These soils are on eroded fan remnants, eroded fan remnant side slopes, and escarpments. Slopes are 0 to 35 percent. Mean annual precipitation is about 430 mm, and mean annual air temperature is about 4.4 degrees C.
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Haplustepts
TYPICAL PEDON: Midnot clay loam, in Rangeland on an 11 percent slope at an elevation of 1,430 meters (colors are for dry soil unless otherwise noted).
A--0 to 9 cm; dark grayish brown (2.5Y 4/2) clay loam, very dark grayish brown (2.5Y 3/2) moist; moderate very fine platy and weak very fine granular structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine and coarse roots; common very fine and coarse irregular and tubular pores; 6 percent gravel; slightly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (6 to 10 cm thick)
Bk1--9 to 23 cm; light gray (2.5Y 7/2) gravelly silty clay loam, light olive brown (2.5Y 5/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine and coarse roots; common very fine interstitial and tubular pores; 10 percent fine calcium carbonate masses on faces of peds; 18 percent gravel and 12 percent paragravel; slightly effervescent; moderately alkaline (pH 8.2); clear smooth boundary.
Bk2--23 to 43 cm; light yellowish brown (2.5Y 6/3) gravelly silty clay loam, light olive brown (2.5Y 5/3) moist; moderate medium and coarse angular blocky structure; very hard, friable, very sticky and very plastic; few very fine roots; few very fine tubular and irregular pores; 20 percent fine and medium calcium carbonate masses on faces of peds; 30 percent gravel and 15 percent paragravel; violently effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (combined thickness of Bk horizons is 25 to 60 cm)
BCk--43 to 78 cm; light brownish gray (2.5Y 6/2) gravelly silty clay, dark grayish brown (2.5Y 4/2) moist; massive; very hard, friable, very sticky and very plastic; few very fine roots; few very fine tubular and irregular pores; finely disseminated carbonates and 2 percent medium calcium carbonate masses in the matrix; 17 percent gravel and 20 percent paragravel; violently effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (0 to 40 cm thick)
Cr--78 to 150 cm; moderately cemented, semi-consolidated cretaceous shale; strongly alkaline (pH 8.7)
TYPE LOCATION: Wheatland County Area, Montana; located about 1.6 kilometers northwest of Judith Gap, Montana; 424 meters east and 27 meters south of the NW corner of section 25, T11N, R5E; Judith Gap topographic quadrangle; UTM 12T, 593121e, 5171809n, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 7 degrees C
Depth to secondary calcium carbonate accumulation - 6 to 10 cm
Depth to paralithic contact - 50 to 100 cm
Some pedons have a Bky horizon.
A horizon
Hue: 10YR or 2.5Y
Value: 4, 5 or 6 dry; 3 or 4 moist
Chroma: 2 or 3
Texture: clay loam, silty clay loam, or silty clay
Clay content: 28 to 45 percent
Rock fragments: 0 to 15 percent gravel
Reaction: pH 7.8 to 8.4
Bk1 horizon
Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: silty clay loam, clay loam, silty clay, or clay
Clay content: 30 to 50 percent
Rock fragments: 0 to 35 percent gravel
Pararock fragments: 0 to 35 percent paragravel
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 8.0 to 8.6
Bk2 horizon
Hue: 10YR or 2.5Y
Value: 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3 or 4
Texture: silty clay loam, clay loam, silty clay, or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 35 percent gravel
Pararock fragments: 0 to 50 percent paragravel
Calcium carbonate equivalent: 5 to 15 percent
Sodium adsorption ratio: 0 to 8
Reaction: pH 8.0 to 9.0
BCk horizon
Hue: 10YR, 2.5Y or 5Y
Value: 4, 5, or 6 dry; 4 or 5 moist
Chroma: 2 or 3
Texture: silty clay, silty clay loam, clay loam, or clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 35 percent gravel
Pararock fragments: 0 to 50 percent paragravel
Calcium carbonate equivalent: 2 to 15 percent
Sodium adsorption ratio: 0 to 13
Reaction: pH 8.0 to 9.0
COMPETING SERIES:
Widen (MT) - have a cambic horizon; do not have secondary calcium carbonate accumulation above 25 cm
Sagedale (MT) - do not have a paralithic contact
GEOGRAPHIC SETTING:
Landform - fan remnants, eroded fan remnants, and escarpments
Elevation - 1,350 to 1,830 meters
Slope - 0 to 35 percent
Parent material - alluvium or colluvium over residuum
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 380 to 500 mm
Mean annual air temperature - 3 to 6 degrees C
Frost-free period - 70 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow and slow permeability.
USE AND VEGETATION: Midnot soils are used as rangeland and non-irrigated cropland. Potential native vegetation is mainly western wheatgrass, green needlegrass, Idaho fescue, and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Midnot soils are of small extent in central Montana. MLRA 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES PROPOSED: Wheatland County (Wheatland County Area), Montana, 2011. The name is coined.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from 0 to 9 cm (A horizon)
Secondary calcium carbonate accumulation - from 9 to 23 cm (Bk1, Bk2, and BCk horizons)
Paralithic contact - at 78 cm (Cr horizon)
Particle-size control section - from 25 to 78 cm (Bk2 and BCk horizons)
Midnot soils have a frigid temperature regime and an ustic moisture regime.
ADDITIONAL DATA: Kellogg Soil Survey Laboratory - 06N1013.
National Cooperative Soil Survey
U.S.A.