LOCATION ROLOFF WA+OREstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Aridic Haploxerolls
TYPICAL PEDON: Roloff silt loam - grassland. (Colors are for dry soil unless otherwise stated.)
A--0 to 8 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium and thick platy structure that parts to fine and medium granular; soft, very friable, slightly sticky and slightly plastic; many fine roots; few very fine tubular pores; neutral (pH 7.0); clear smooth boundary. (7 to 12 inches thick)
Bw1--8 to 16 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; few very fine tubular pores; slightly alkaline (pH 7.6); clear wavy boundary. (6 to 20 inches thick)
Bw2--16 to 24 inches; brown (7.5YR 5/4) silt loam, dark brown (7.5YR 4/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; few very fine tubular pores; 10 percent fine pebbles; slightly alkaline (pH 7.8); abrupt smooth boundary. (0 to 15 inches thick)
2R--24 inches; unweathered basalt.
TYPE LOCATION: Adams County, Washington; 700 feet west and 300 feet south of the north quarter corner of sec. 15, T. 18 N., R. 35 E., W.M.
RANGE IN CHARACTERISTICS: The soil temperature at a depth of 20 inches ranges from 50 to 56 degrees F. These soils are usually dry in all parts between depths of 8 to 24 inches, or the surface of the bedrock if shallower. Depth to bedrock ranges from 20 to 40 inches. These soils have hue of 7.5YR or 10YR. The particle-size control section averages 0 to 25 percent coarse fragments. The mollic epipedon is 7 to 15 inches thick.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, chroma of 2 or 3 dry or moist. Reaction is neutral or slightly alkaline.
The Bw1 horizon has value of 4 to 6 dry, 3 or 4 moist, and chroma of 2 or 3 moist and 2, 3, or 4 dry. It is silt loam or very fine sandy loam. Reaction is neutral to strongly alkaline.
The Bw2 horizon has value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 through 4 dry or moist. It is silt loam, gravelly silt loam, very fine sandy loam or gravelly loam. Reaction is slightly alkaline to strongly alkaline.
COMPETING SERIES: These are the Burch, Calpine, Caphealy, Cashmere, Cashmont, Rio King, Roosevelt, Sevenmile, Shantown, Snake Hollow, and Surprise series. All of these soils except Caphealy and Roosevelt lack bedrock within a depth of 40 inches. Caphealy soils are moderately deep to a paralithic contact and have 10 to 25 percent pumice sand throughout the profile. Roosevelt soils have a Bw horizon that is sandy loam or fine sandy loam.
GEOGRAPHIC SETTING: Roloff soils are on ridges, benches, hillslopes and escarpments at elevations of 200 to 2,200 feet. Slopes are 0 to 70 percent. The soils formed in loess and glaciofluvial deposits over basalt. They are in a semiarid climate with warm, dry summers and cool, moist winters. The average annual precipitation ranges from 9 to 12 inches. The average January temperature is 29 degrees F. The average July temperature is 71 degrees F. The average annual temperature is 47 to 54 degrees F. The frost-free season is 135 to 185 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bakeoven, Farrell, Magallon, Olex, and Stratford soils. These soils except for Bakeoven are more than 40 inches deep. Bakeoven soils are very shallow to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; moderate permeability.
USE AND VEGETATION: Mostly for range. Vegetation is bluebunch wheatgrass, Sandberg bluegrass, giant wildrye, threadleaf sedge, wild buckwheat, western yarrow, cheatgrass, rabbitbrush, and big sagebrush.
DISTRIBUTION AND EXTENT: Eastern Washington and north-central Oregon. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Adams County, Washington, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 8 inches, a cambic horizon from 8 to 16 inches and lithic contact at 24 inches.