LOCATION SWAMPCREEK MT
Established Series
Rev. DRS-JAL-JCK
07/2013
SWAMPCREEK SERIES
The Swampcreek series consists of very deep, poorly drained soils that formed in alluvium from mixed sources. These soils are on flood plains, drainageways, and stream terraces. Slopes are 0 to 8 percent. Mean annual precipitation is about 406 mm, and mean annual temperature is about 6 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Endoaquolls
TYPICAL PEDON: Swampcreek gravelly sandy clay loam, in grassland (colors are for moist soil unless otherwise noted).
A--0 to 20 cm; very dark grayish brown (10YR 3/2) gravelly sandy clay loam; dark grayish brown (10YR 4/2) dry; weak fine granular structure; slightly hard, friable, slightly sticky and moderately plastic; many very fine, fine and medium roots; common very fine and fine pores; 25 percent gravel and 5 percent cobbles; slightly effervescent; slightly alkaline (pH 7.8); abrupt smooth boundary. (18 to 36 cm thick)
Bw--20 to 46 cm; dark grayish brown (10YR 4/2) loam, grayish brown (10YR 5/2) dry; common medium and coarse prominent strong brown (7.5YR 5/6) moist redox concentrations; few fine distinct gray (10YR 5/1) moist redox depletions; weak medium prismatic structure parting to moderate fine and medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine and many medium roots; common fine and very fine pores; 10 percent gravel; slightly effervescent; slightly alkaline (pH 7.8); gradual smooth boundary. (13 to 33 cm thick)
Bkg1--46 to 76 cm; dark grayish brown (2.5Y 4/2) very gravelly coarse sandy loam, grayish brown (2.5Y 5/2) dry; common fine distinct dark yellowish brown (10YR 4/6) moist redox concentrations; weak fine and medium blocky structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots; many fine and very fine pores and few medium pores; 35 percent gravel and 10 percent cobbles; common fine irregular calcium carbonate masses; common distinct carbonate coats on bottom surfaces of rock fragments; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (15 to 51 cm thick)
Bkg2--76 to 155 cm; olive gray (5Y 5/2) extremely gravelly loamy coarse sand, gray (5Y 6/1) dry; single grain; loose, nonsticky and nonplastic; few fine roots; 50 percent gravel and 15 percent cobbles; common fine soft calcium carbonate masses; common distinct carbonate coats on bottom surfaces of rock fragments; strongly effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Sweet Grass County, Montana; 457 meters south and 30 meters east of the northwest corner of Section 32, T.5 N., R.14 E.; Latitude - 46 degrees, 8 minutes, 6 seconds North; Longitude - 110 degrees, 27 seconds West.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 5 to 8 degrees C
Mollic epipedon thickness - 18 to 36 cm
Depth to sandy-skeletal material - 50 to 100 cm
Depth to redox features - 20 to 36 cm
Depth to seasonal high water table - 30 to 60 cm (20 to 60 cm where irrigated)
A horizon
Hue: 10YR or 2.5Y
Value: 3, 4, or 5 dry; 2 or 3 moist
Chroma: 1 or 2
Texture: sandy clay loam, loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 15 to 35 percent--15 to 30 percent gravel; 0 to 5 percent cobbles
Reaction: pH 6.6 to 8.0
Bw horizon
Hue: 10YR or 2.5Y
Value: 4, 5 or 6 dry; 3, 4, or 5 moist
Texture: loam, sandy clay loam or clay loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 35 percent--0 to 30 percent gravel; 0 to 5 percent cobbles
Reaction: pH 6.6 to 8.4
Bkg1 horizon
Hue: 2.5Y or 5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 1 or 2
Texture: coarse sandy loam, sandy loam or loam
Clay content: 5 to 18 percent
Rock fragments: 35 to 60 percent--30 to 45 percent gravel; 5 to 15 percent cobbles
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.8 to 8.4
Bkg2 horizon
Hue: N, 2.5Y, or 5Y
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 0, 1, or 2
Texture: loamy coarse sand, sand, coarse sand or loamy sand
Clay content: 1 to 10 percent
Rock fragments: 50 to 80 percent--40 to 55 percent gravel, 10 to 25 percent cobbles, 0 to 10 percent stones
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.8 to 8.4
COMPETING SERIES:
Allwit (ID) - do not have horizons of strong gleying or secondary calcium carbonate accumulation
Irim (CO) - do not have horizons of secondary calcium carbonate accumulation; have hues redder than 10YR
Lehmandow (NV) - do not have horizons of secondary calcium carbonate accumulation; have more than 10 percent stones throughout the subsoil
Mccalla (MT) - do not have horizons of strong gleying or secondary calcium carbonate accumulation
Poronto (MT) - do not have horizons of secondary calcium carbonate accumulation; have hues redder than 10YR
GEOGRAPHIC SETTING:
Landform - flood plains, drainageways, and stream terraces
Elevation - 1,097 to 1,890 meters
Slope - 0 to 8 percent
Parent material - alluvium
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 254 to 483 mm
Mean annual air temperature - 2.7 to 8 degrees C
Frost-free period - 70 to 130 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Poorly drained; moderate over moderately rapid and rapid permeability.
USE AND VEGETATION: Swampcreek soils are used mainly for pasture, hay, and rangeland, and to a lesser degree, for cropland. Potential native vegetation is mainly slender wheatgrass, reed canarygrass, prairie cordgrass, American mannagrass, tall sedges, forbs, and willows.
DISTRIBUTION AND EXTENT: Swampcreek soils are of small extent in south central Montana. MLRAs - 43B, 44B, 46, 58A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Sweet Grass County, Montana, 1998.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 20 cm (A horizon)
Cambic horizon from - 20 to 46 cm (Bw horizon)
Secondary calcium carbonate accumulation from - 46 to 155 cm (Bkg1 and Bkg2 horizons)
Redox depletions - from 20 to 46 cm (Bw horizon)
Redox concentrations - from 20 to 76 cm (Bw and Bkg1 horizons)
Particle-size control section from 25 to 100 cm (part of the Bw, Bkg1, and Bkg2 horizons)
Swampcreek soils have a frigid temperature regime and an aquic moisture regime.
ADDITIONAL DATA: Soil interpretations record - MT1490. NSSL 91P1572. Seasonal water table data was collected from May - September at the type location, from 1990 - 1993.
National Cooperative Soil Survey
U.S.A.