LOCATION YACREEK MT
Established Series
Rev. JJU-RJS
01/2012
YACREEK SERIES
The Yacreek series consists of very deep, well drained soils that formed in alluvium or lacustrine deposits over alluvium. These soils occur on fan remnants and lake beds. Slopes are 0 to 8 percent. Mean annual precipitation is about 400 mm, and the mean annual air temperature is about 3 degrees C.
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive Calcic Argicryolls
TYPICAL PEDON: Yacreek loam, in rangeland on a 2 percent slope at an elevation of 2,029 meters (colors are for dry soil unless otherwise noted).
A--0 to 10 cm; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, and common medium roots; many very fine and fine irregular pores; 5 percent gravel; slightly alkaline (pH 7.6); clear smooth boundary. (8 to 14 cm thick)
Bt--10 to 31 cm; brown (10YR 4/3) clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; many very fine and fine, and common medium roots; many very fine and fine irregular pores; 10 percent gravel; 45 percent distinct clay films on faces of peds; slightly alkaline (pH 7.6); clear wavy boundary. (10 to 25 cm thick)
Bk--31 to 48 cm; pale brown (10YR 6/3) gravelly sandy clay loam, light brownish gray (10YR 6/2) moist; moderate fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many fine irregular pores; 30 percent gravel; finely disseminated calcium carbonate; 70 percent fine distinct irregular calcium carbonate coats around rock fragments; violently effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (13 to 20 cm thick)
2BCk--48 to 152 cm; light yellowish brown (10YR 6/4) extremely gravelly sand, pale brown (10YR 6/3) moist; single grain; loose, nonsticky and nonplastic; 65 percent gravel; finely disseminated calcium carbonate; 60 percent fine distinct irregular calcium carbonate coats around rock fragments; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Beaverhead County, Montana; located about 399 meters south and 545 meters east of the northwest corner of sec. 30, T. 14S, R. 5W; Monida topographic quadrangle; UTM 12T, 399455e, 4938182n, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 2 to 5 degrees C.
Thickness of mollic epipedon - 18 to 36 cm
Depth to argillic horizon - 8 to 14 cm
Depth to calcic horizon - 18 to 38 cm
Depth to lithologic discontinuity - 36 to 50 cm
A horizon
Value: 3 or 4 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Clay content: 18 to 27 percent
Rock fragments: 0 to 15 percent gravel
Reaction: pH 6.6 to 7.8
Bt horizon
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: loam or clay loam
Clay content: 24 to 35 percent
Rock fragments: 0 to 15 percent gravel
Reaction: pH 6.6 to 7.8
Bk horizon
Value: 5 or 6; dry or moist
Chroma: 3 or 4; dry or moist
Texture: loam or sandy clay loam
Clay content: 18 to 27 percent
Rock fragments: 15 to 35 percent gravel
Calcium carbonate equivalent: 15 to 35 percent
Reaction: pH 7.9 to 8.4
2BCk horizon
Value: 5 or 6; dry or moist
Chroma: 3 or 4; dry or moist
Texture: loamy sand or sand
Clay content: 2 to 10 percent
Rock fragments: 60 to 80 percent gravel
Calcium carbonate equivalent: 5 to 15 percent
Reaction: pH 7.9 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - fan remnants and lake beds
Elevation - 1,980 to 2,140 meters
Slope - 0 to 8 percent
Parent material - alluvium or lacustrine deposits over alluvium
Climate - long, cold winters; moist springs; short warm summers
Mean annual precipitation - 380 to 480 mm
Mean annual air temperature - 1 to 4 degrees C.
Frost-free period - 50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderately over rapid.
USE AND VEGETATION: Yacreek soils are used as native rangeland. Native vegetation is mainly Idaho fescue, prairie junegrass, poa (species), threetip sagebrush, and other miscellaneous grasses and forbs.
DISTRIBUTION AND EXTENT: Yacreek 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:
Mollic epipedon - from 0 to 31 cm (A, Bt horizons)
Argillic horizon - from 10 to 31 cm (Bt horizon)
Calcic horizon - from 31 to 152 cm (Bk, 2BCk horizons)
Particle-size control section - from 10 to 100 cm (Bt, Bk, part of 2BCk horizons)
Yacreek soils have a cryic temperature regime and an ustic moisture regime.
Taxonomic version: Eleventh Edition, 2010.
National Cooperative Soil Survey
U.S.A.