LOCATION WHITEARTH MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Typic Natrixeralfs
TYPICAL PEDON: Whitearth silt loam, in rangeland (colors are for dry soil unless otherwise noted).
Ap--0 to 5 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; moderate medium subangular blocky structure parting to moderate medium granular; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; common very fine tubular pores; moderately alkaline (pH 8.2); abrupt smooth boundary. (3 to 7 inches thick)
Btn--5 to 9 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 4/3) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, firm, slightly sticky and plastic; common very fine roots; common very fine tubular pores; common thin clay films on ped faces and in pores; strongly alkaline (pH 8.6); clear wavy boundary. (3 to 5 inches thick)
Bkn--9 to 32 inches; very pale brown (10YR 7/3) silty clay loam, pale brown (10YR 6/3) moist; weak medium prismatic structure parting to moderate coarse subangular blocky; hard, fine, sticky and plastic; few very fine roots; few very fine tubular pores; few distinct masses of lime; strongly effervescent; very strongly alkaline (pH 9.6); clear wavy boundary. (8 to 24 inches thick).
C1--32 to 49 inches; white (10YR 8/2) silt loam, pale brown (10YR 6/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine tubular pores; disseminated lime; strongly effervescent; strongly alkaline (pH 9.0); clear wavy boundary. (12 to 18 inches thick)
C2--49 to 60 inches; very pale brown (10YR 7/3) silt loam, brown (10YR 5/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; disseminated lime; strongly effervescent; strongly alkaline (pH 9.0).
TYPE LOCATION: Lake County, Montana; 2,550 feet east and 1,400 feet north of the SW corner of sec. 17, T. 22 N., R. 21 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 43 to 47 degrees F.
Moisture control section - between 4 and 12 inches.
Some pedons have an E horizon in place of the A horizon.
Ap horizon - Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Clay content: 18 to 27 percent
EC: 0 to 4 mmhos/cm
SAR: 5 to 40
Reaction: pH 7.9 to 8.4
Btn horizon - Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3
Clay content: 27 to 35 percent and less than 15 percent fine sand or coarser
EC: 4 to 8 mmhos/cm
SAR: 40 to 60
Reaction: pH 8.5 to 9.6
Bkn horizon - Value: 7 or 8 dry, 5 or 6 moist
Chroma: 3 or 4
Clay content: 27 to 35 percent and less than 15 percent fine sand or coarser
Calcium carbonate equivalent: 10 to 15 percent
EC: 4 to 8
SAR: 20 to 60
Reaction: pH 8.5 to 9.6
C1 horizon - Value: 7 or 8 dry, 5 or 6 moist
Chroma: 2 or 3
Clay content: 10 to 27 percent
Calcium carbonate equivalent: 5 to 10 percent
EC: 4 to 8 mmhos/cm
SAR: 20 to 60
Reaction: pH 8.5 to 9.6
C2 horizon - Value: 7 or 8 dry, 5 or 6 moist
Clay content: 10 to 27 percent
Calcium carbonate equivalent: 5 to 10 percent
EC: 4 to 16 mmhos/cm
SAR: 60 to 75
Reaction: pH 8.5 to 9.6
COMPETING SERIES:
Thatcherflats (ID) - have a water table at depths of 3 to 4 feet; are somewhat poorly drained.
GEOGRAPHIC SETTING:
Landform - dissected alluvial fans, stream terraces, and dissected lake plains.
Elevation - 2,500 to 3,000 feet.
Slope- 0 to 8 percent.
Parent material - silty alluvium derived from lacustrine deposits.
Climate - long, cold winters; moist falls and springs; warm, dry summers.
Mean annual precipitation - 10 to 14 inches, most of which falls as rain or snow in late fall through late spring.
Mean annual temperature - 41 to 45 degrees F.
Frost-free period - 105 to 125 days.
DRAINAGE AND PERMEABILITY: Well drained; slow permeability in the Bt and Bk horizons and moderately slow permeability below.
USE AND VEGETATION: Whitearth soils are used mainly for rangeland and pastureland. The potential native vegetation is basin wildrye, Nuttall alkaligrass, and inland saltgrass.
DISTRIBUTION AND EXTENT: Whitearth soils are of small extent in mountain valleys of northwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Lake County, Montana, 1991; proposed in Lake County, Montana, 1986. Whitearth is a coined name.
REMARKS: Soil interpretation record: MT1049. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the soil surface to 5 inches (Ap horizon); a natric horizon from 5 to 32 inches (Btn and Bkn horizons). Whitearth soils have a frigid temperature regime and a xeric moisture regime bordering on aridic.
Laboratory Data: S85MT-047-008