LOCATION SPOFMORE WA+IDEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Typic Natrixerolls
TYPICAL PEDON: Spofmore silt loam-cultivated on 4 percent northeast facing slopes at an elevation of 2,790. (Colors are for dry soil unless otherwise noted)
Ap--0 to 7 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; hard, friable, sticky and plastic; many very fine roots; many very fine irregular pores; neutral (pH 7.2); abrupt smooth boundary. (6 to 9 inches thick)
Btn1--7 to 11 inches; brown (10YR 5/3) silty clay, very dark grayish brown (10YR 3/2) moist; many very dark brown (10YR 2/2) organic coatings on faces of peds; strong fine and medium prismatic structure parting to moderate medium angular blocky; very hard, very firm, sticky and plastic; common very fine exped roots; common very fine irregular pores; continuous moderately thick stress cutans and clay films on faces of peds and clay films lining some pores; mildly alkaline (pH 7.6): clear wavy boundary. (3 to 6 inches thick)
Btn2--11 to 18 inches; brown (10YR 5/3) silty clay, dark brown (10YR 3/3) moist; common very dark brown (10YR 2/2) organic coatings on faces of peds;strong medium prismatic structure parting to moderate medium subangular blocky; very hard, very firm, sticky and plastic; common very fine exped roots; many very fine irregular and common very fine tubular pores; continuous moderately thick stress cutans and clay films on faces of peds and clay films lining some pores; moderately alkaline (pH 8.0); clear wavy boundary. (4 to 8 inches thick)
Btk--18 to 24 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, firm, sticky and plastic; few very fine roots; many very fine irregular and common tubular pores; many thin stress cutans and clay films on faces of peds and clay films lining some pores; common coatings of secondary lime on faces of peds and lining pores; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary. (4 to 8 inches thick)
Bk1--24 to 35 inches; light gray (10YR 7/2) silt loam, pale brown (10YR 6/3) moist; massive; hard, friable, sticky and plastic; few very fine roots; many very fine irregular pores; disseminated lime; violently effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (9 to 16 inches thick)
Bk2--35 to 44 inches; brown (10YR 5/3) silt loam, brown (10YR 4/3) moist; massive; slightly hard, friable, sticky and plastic; few very fine roots; many very fine irregular pores; common fine and medium spheroidal aggregates of secondary lime; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (6 to 25 inches thick)
Bk3--44 to 60 inches; brown (10YR 5/3) silt loam, brown (10YR 4/3) moist; massive; slightly hard, friable, sticky and plastic; few very fine roots; many very fine irregular pores; few fine and medium spheroidal aggregates of secondary lime; slightly effervescent; moderately alkaline (pH 8.0)
TYPE LOCATION: Asotin County, Washington; about 6 miles northeast of Anatone; 1,100 feet north and 2,100 feet west of southeast corner of sec. 28, T. 9 N., R. 46 E.
RANGE IN CHARACTERISTICS: Depth of the calcic horizon is 20 to 30 inches. The mean annual temperature is 47 to 51 degrees F. These soils are usually moist, but are dry in all parts between 4 and 12 inches for 75 to 90 consecutive days following summer solstice. The particle-size control section averages 35 to 45 percent clay. The mollic epipedon is 15 to 20 inches thick and includes part of the natric horizon. Natric horizon has SAR of 13 to 30. A thin B/E horizon is in some pedons just above the Btn horizon.
The A horizon has value of 4 or 5 cry and 2 or 3 moist. It is neutral or mildly alkaline.
The Btn has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3 dry or moist. It has prismatic, subangular blocky, or columnar structure.
The Btk horizon has value of 3 or 4 moist and chroma of 2 or 3 moist. It is moderately alkaline or strongly alkaline.
The Bk horizon has value of 5 through 7 dry, 4 through 6 moist and chroma of 2 or 3 dry or moist. It is silt loam or silty clay loam. It is moderately alkaline or strongly alkaline.
COMPETING SERIES: This is the Trenton series. Trenton soils are calcareous throughout and have grayish mottles within 40 inches of the surface.
GEOGRAPHIC SETTING: Spofmore soils are on basalt plateaus. Slopes are 3 to 30 percent. These soils formed in loess. Elevations range from 2,600 to 3,700 feet. Summers are warm and dry and winters are cool and moist. The average annual precipitation ranges from 15 to 17 inches. Mean annual air temperature is about 47 degrees F. Frost-free season is 125 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: They are the Laufer, Limekiln, Neissenberg, Pataha, Rockly, Stember and Thiessen soils. Laufer, Limekiln and Rockly soils have a lithic contact at a depth of less than 20 inches. Neissenberg, Pataha, Stember and Thiessen soils have a lithic contact at a depth of less than 40 inches.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium to very rapid runoff; slow permeability.
USE AND VEGETATION: Used for cropland. Native vegetation is mainly bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass, arrowleaf balsamroot, and western yarrow.
DISTRIBUTION AND EXTENT: Southeastern Washington and adjacent area in Idaho. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Asotin County, Washington, 1984.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 14 inches, a natric horizon from 7 to 18 inches, and a calcic horizon from 24 to 44 inches.