LOCATION FAIRBIRCH MT
Tentative Series
Rev. JAL/EMM
10/2014
FAIRBIRCH SERIES
The Fairbirch series consists of very deep, poorly drained soils that formed in alluvium. These soils are on flood plains. Slopes are 0 to 2 percent. Mean annual precipitation is about 400 mm and mean annual temperature is about 5 degrees C.
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Fluvaquentic Endoaquolls
TYPICAL PEDON: Fairbirch silt loam, in irrigated hayland (colors are for dry soil unless otherwise noted).
Ap--0 to 13 cm; dark gray (10YR 4/1) silt loam, very dark gray (10YR 3/1) moist; moderate very fine and fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots; slightly alkaline (pH 7.4); clear smooth boundary. (10 to 20 cm thick)
A2--13 to 38 cm; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; weak medium prismatic structure parting to weak medium and fine subangular blocky; slightly hard, friable, moderately sticky and slightly plastic; common very fine roots; common very fine tubular and interstitial pores; slightly alkaline (pH 7.4); clear smooth boundary. (15 to 25 cm)
Bg1--38 to 58 cm; gray (10YR 6/1) silty clay loam, dark gray (10YR 4/1) moist; weak medium and fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine roots; common very fine tubular and interstitial pores; common fine prominent brown (7.5YR 5/4) redox concentrations, moist; neutral (pH 7.0); clear smooth boundary. (10 to 30 cm)
Bg2--58 to 91 cm; light gray (5Y 7/2) gravelly loam, olive (5Y 5/3) moist; weak medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; many fine and medium prominent brown (7.5YR 5/4) redox concentrations, moist; 20 percent gravel; neutral (pH 6.8); gradual smooth boundary. (combined thickness of Bg horizons is 25 to 80 cm thick)
2Cg--91 to 150 cm; light gray (5Y 7/2) very gravelly loam, olive gray (5Y 5/2) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few fine and medium prominent brown (7.5YR 5/4) redox concentrations, moist; 35 percent gravel, 5 percent cobbles; neutral (pH 7.3).
TYPE LOCATION: Meagher County, Montana; 1,300 feet west and 800 feet north of the SE corner of sec. 10, T. 9 N., R. 5 E.
RANGE IN CHARACTERISTICS:
Soil temperature - 4.4 to 7.2 degrees C.
Mollic epipedon thickness - 25 to 38 cm
Depth to very gravelly 2C horizon - 63 to 100 cm
Depth to water table - 30 to 60 cm
A horizons
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 or 2 dry or moist
Clay content: 15 to 25 percent
Reaction: pH 6.6 to 7.8
Bg1 horizon
Hue: 10YR or 2.5Y
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 1 or 2 dry or moist
Redoximorphic features - Value: 5 or 6 dry, 4 or 5 moist; Chroma: 4 or 6
Texture: loam, silt loam, silty clay loam
Clay content: 18 to 30 percent
Reaction: pH 6.6 to 7.8
Bg2 horizon
Hue: 2.5Y or 5Y
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 1, 2, or 3 dry or moist
Redoximorphic features - Value: 5 or 6 dry, 4 or 5 moist; Chroma: 4 or 6
Texture: loam or sandy loam
Clay content: 10 to 20 percent
Rock fragments: 0 to 25 percent gravel
Reaction: pH 6.6 to 7.8
2Cg horizon
Hue: 2.5Y or 5Y
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 1 or 2 dry or moist
Redoximorphic features - Value: 5 or 6 dry, 4 or 5 moist; Chroma: 4 or 6
Texture: loam or sandy loam
Clay content: 5 to 15 percent
Rock fragments: 35 to 60 percent--0 to 10 percent cobbles, 35 to 50 percent gravel
Reaction: pH 6.6 to 7.8
COMPETING SERIES:
Clunton (MT) - does not have loamy-skeletal material above a depth of 150 cm; does not have Bg horizons.
Hayspur (NV) - does not have loamy-skeletal material above a depth of 150 cm; has concretions of Mn oxides above 150 cm; has sandy-skeletal material below a depth of 100 cm.
Moynier (UT) - does not have loamy-skeletal material above a depth of 150 cm; is very poorly drained.
GEOGRAPHIC SETTING:
Landform - flood plains
Elevation - 1,225 to 1,800 meters
Slope - 0 to 2 percent
Parent material - alluvium
Climate - long, cold winters; moist springs; short, warm summers
Mean annual precipitation - 380 to 480 mm
Mean annual air temperature - 3.3 to 6.1 degrees C
Frost-free period - 70 to 100 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Poorly drained; moderate permeability.
USE AND VEGETATION: Fairbirch soils are used mainly for rangeland and irrigated and nonirrigated hayland. The potential native vegetation is mainly tall reedgrass, mannagrass, tufted hairgrass, bearded wheatgrass, slender wheatgrass, sedges, other perennial grasses, forbs, and shrubs.
DISTRIBUTION AND EXTENT: Fairbirch soils are of small extent in the mountain valleys of western Montana. MLRAs 44B and 46.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Meagher County, Montana, 1992. Fairbirch is a coined name.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the soil surface to 38 cm (A1, A2 horizons)
Cambic horizon - the zone from 38 to 91 cm (Bg1, Bg2 horizons)
Loamy skeletal material - the zone from 91 to 150 cm (2Cg horizon)
Particle-size control section - the zone from 25 to 100 cm (A2, Bg1, Bg2, 2Cg horizons)
Fairbirch soils have a frigid temperature regime and an aquic moisture regime.
Soil interpretation record: MT1467.
National Cooperative Soil Survey
U.S.A.