LOCATION OLIPHANT WA+ID OREstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, mesic Calcic Pachic Haploxerolls
TYPICAL PEDON: Oliphant silt loam - cultivated. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 9 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; neutral (pH 7.0); abrupt wavy boundary. (5 to 9 inches thick)
A--9 to 16 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak coarse prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; many fine pores; slightly alkaline (pH 7.4); clear wavy boundary. (0 to 9 inches thick)
Bw1--16 to 26 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak coarse and medium prismatic structure; hard, friable, slightly sticky and slightly plastic; common roots; common fine pores; few thin coatings; moderately alkaline (pH 8.0); clear wavy boundary. (7 to 15 inches thick)
Bw2--26 to 41 inches; brown (10YR 5/3) silt loam, brown (10YR 4/3) moist; weak medium prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; few masses of soft powdery lime; slightly effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (8 to 40 inches thick)
2Bk--41 to 53 inches; very pale brown (10YR 8/2) extremely gravelly silt loam, light brownish gray (10YR 6/2) moist; massive; slightly hard, friable, slightly sticky and nonplastic; few roots; 70 percent lime coated basalt fragments; violently effervescent; strongly alkaline (pH 8.8); abrupt wavy boundary. (0 to 14 inches thick)
3R--53 inches; basalt with lime in the fractures.
TYPE LOCATION: Garfield County, Washington; 920 feet north and 680 feet west of the southeast corner of sec. 30, T. 13 N., R. 41 E., W.M.
RANGE IN CHARACTERISTICS: Depth to the calcic horizon is 20 to 44 inches. The Bk or 2Bk horizon contains 15 to 30 percent calcium carbonate equivalent. Depth to a lithic contact with basalt is 40 to more than 60 inches. The mean annual soil temperature is 49 to 55 degrees F. These soils are usually moist, but are dry in all parts between 4 and 12 inches for 90 to 105 consecutive days. The particle-size control section averages 10 to 18 percent clay. The mollic epipedon is 20 to 30 inches thick.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3 moist and dry. It has weak granular, subangular blocky or prismatic structure. This horizon is neutral or slightly alkaline.
The Bw horizon has value of 5 through 7 dry, 3 through 5 moist, and chroma of 2 through 4 dry or moist. It has weak or moderate structure. This horizon is slightly alkaline to strongly alkaline.
A Bk horizon is present in some pedons having color value of 6 through 8 dry, 4 through 6 moist, and chroma of 2 through 4 dry or moist. It is moderately alkaline or strongly alkaline.
The 2Bk horizon has hue of 2.5Y or 10YR, value of 6 to 8 dry, 3 to 6 moist, and a chroma of 2 through 4 dry or moist. It is moderately alkaline to very strongly alkaline. It is silt loam, or loam and is gravelly, very gravelly, extremely gravelly or very cobbly.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Oliphant soils are on plateaus, hillslopes and terraces at elevations of 600 to 2,700 feet. Slopes are 0 to 55 percent. Oliphant soils formed in loess over slope alluvium and colluvium from basalt and loess over lacustrine sediment. Summers are warm and dry, winters are cool and moist. The average annual precipitation is 12 to 16 inches. The average July temperature is 68 to 73 degrees F. The average January temperature is 22 to 32 degrees F. The mean annual air temperature is 47 to 53 degrees F. The frost-free season is 110 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anders, Asotin, Bakeoven, Chard, Nims, Spofford, Walla Walla, and Weissenfels soils. Anders, Asotin, Nims, and Weissenfels soils have lithic contact with basalt at depths of 20 to 40 inches. Bakeoven soils are 4 to 10 inches to lithic contact with basalt. Chard soils are coarse-loamy. Spofford and Weissenfels soils have a natric horizon. Walla Walla soils lack a Bk horizon within 44 inches.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Primarily used for nonirrigated cropland, with minor amounts of irrigated cropland. Uncleared areas are used for livestock grazing. Winter wheat is the common crop. Native vegetation is bluebunch wheatgrass, Sandberg bluegrass, and small amounts of Idaho fescue.
DISTRIBUTION AND EXTENT: Eastern Washington, northeastern Oregon and northcentral Idaho; MLRA 8 and 9. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Garfield County (Garfield County Area), Washington, 1970.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 26 inches, a cambic horizon from 26 to 41 inches, and a calcic horizon from 41 to 53 inches.
ADDITIONAL DATA: Whitman County, Washington; S85WA-075-003; S85WA-075-005; Nez Perce County, Idaho; S84ID-069-008.