LOCATION ASOTIN WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Calcic Haploxerolls
TYPICAL PEDON: Asotin silt loam - range. (Colors are for dry soil unless otherwise noted.)
A1--0 to 6 inches; dark grayish brown (10YR 4/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak very fine granular structure; slightly hard, very friable, slightly sticky and nonplastic; many very fine and few medium roots; many fine and very fine pores in peds; neutral (pH 7.3); clear wavy boundary. (4 to 6 inches thick)
A2--6 to 13 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; common fine and few medium roots; common fine and very fine and few medium pores; few 3mm to 25mm basalt fragments; neutral (pH 7.0); gradual wavy boundary. (6 to 10 inches thick)
Bw1--13 to 22 inches; pale brown (10YR 6/3) silt loam, dark grayish brown (10YR 4/2) moist; weak prismatic structure; hard, friable, slightly sticky and slightly plastic; common fine and few medium roots; common fine and few medium pores; 5 percent small basalt gravel; slightly alkaline (pH 7.6); clear wavy boundary.
Bw2--22 to 28 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; weak prismatic structure; hard, friable, slightly sticky and slightly plastic; few medium roots; many very fine pores; 10 percent basalt gravel; moderately alkaline (pH 8.0); abrupt smooth boundary. (combined thickness of the Bw horizon is 3 to 22 inches thick)
Bk--28 to 32 inches; light gray (10YR 7/2) silt loam, light brownish gray (10YR 6/2) moist; massive; hard, firm, slightly sticky, slightly plastic; few medium and fine roots; many fine pores partially filled with lime; 10 percent basalt gravel; strongly effervescent; strongly alkaline (pH 8.6); abrupt irregular boundary. (3 to 10 inches thick)
2R--32 inches; basalt with lime in fractures.
TYPE LOCATION: Columbia County, Washington; 250 feet southeast of gate and 300 feet west of Krause road, 2,000 feet west and 2,300 feet and 2,300 feet south of the northeast corner of section 36, T. 12 N., R. 38 E.
RANGE IN CHARACTERISTICS: Depth to a calcic horizon is 15 to 35 inches. Depth to a lithic contact with basalt is 20 to 40 inches. The mean annual soil temperature is 50 to 55 degrees F. The 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 in the fine earth fraction and averages 0 to 20 percent basalt fragments. The mollic epipedon is 10 to 16 inches thick.
The A horizon has value of 4 or 5 dry and 2 or 3 moist. Soil reaction is neutral or slightly alkaline.
The Bw horizon has value of 5 or 6 dry, 3 or 4 moist and chroma of 2 or 3 dry or moist. Soil reaction is slightly alkaline or moderately alkaline.
The Bk horizon has value of 5 to 8 dry, 4 to 7 moist and chroma of 2 or 3 dry or moist. Texture is gravelly silt loam or silt loam. Soil reaction is moderately or strongly alkaline.
COMPETING SERIES: These are the
Bolicker,
Chard,
Disautel,
Dufur and
Kidman series. The
Marriott and
Molcal series have a similar classification.
Bolicker soils greater than 60 inches to lithic contact; dry for 75 to 90 consecutive days
Chard soils - greater than 60 inches to lithic contact
Disautel soils - greater than 40 inches to lithic contact; densic material at depths of 30 to 60 inches
Dufur soils 40 to 60 inches to paralithic contact; dry for 80 to 90 consecutive days
Kidman soils - greater than 60 inches to lithic contact
Marriott soils - greater than 60 inches to lithic contact; active CEC activity class
Molcal soils - greater than 60 inches to lithic contact; dry for 60 to 90 consecutive days; vitrandic subgroup
GEOGRAPHIC SETTING: Asotin soils are on canyon side slopes and hillslopes at elevations of 800 to 2,600 feet. Slopes are 0 to 90 percent. Asotin soils formed in loess, and colluvium from basalt together with minor amounts of volcanic ash. Summers are warm and dry and winters are cool and moist. The mean annual precipitation is 12 to 16 inches. The mean January temperature is 30 to 34 degrees F. and the mean July temperature is 68 to 70 degrees F. The mean annual temperature is 48 to 54 degrees F. The frost-free season is 135 to 160 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kuhl, Lickskillet, Oliphant, Spofford, Schuelke, and Walla Walla soils, in addition to the competing Bolicker soils. Kuhl and Lickskillet soils have bedrock at depths of 10 to 20 inches And are on plateaus and canyon slopes. Schuelke soils are loamy-skeletal and are on canyon slopes. Spofford soils have natric horizons and are on plateaus and hills. Oliphant and Walla Walla soils are coarse-silty and are more than 40 inches deep to a lithic contact. Oliphant soils are on plateaus and Walla Walla soils are on hills.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: These soils are used mainly for livestock grazing and wildlife habitat. Winter wheat is grown on flatter slopes. Native vegetation is mainly bluebunch wheatgrass, Idaho fescue, and Sandberg bluegrass.
DISTRIBUTION AND EXTENT: Southeastern Washington. This series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Asotin County, Washington, 1944
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 0 to 13 inches
Cambic horizon - the zone from 13 to 28 inches
Calcic horizon - the zone from 28 to 32 inches
Lithic contact - the zone beginning at 32 inches