LOCATION STEVENS WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Vitrandic Haploxerolls
TYPICAL PEDON: Stevens ashy silt loam - cultivated. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 8 inches; dark gray (10YR 4/1) ashy silt loam, black (10YR 2/1) moist; weak fine and medium granular structure; soft, friable, slightly sticky and slightly plastic; many fine roots; 2 percent pebbles; neutral (pH 6.8); abrupt smooth boundary. (5 to 9 inches thick)
A1--8 to 15 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak medium prismatic structure that parts to weak medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; few fine pores; 5 percent pebbles; neutral (pH 6.6); clear wavy boundary. (4 to 9 inches thick)
A2--15 to 19 inches; dark grayish brown (10YR 4/2) silt loam, very dark brown (10YR 2/2) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; common fine pores; 10 percent pebbles; neutral (pH 6.8); gradual wavy boundary. (3 to 6 inches thick)
BA--19 to 30 inches; brown (10YR 5/3) gravelly loam, dark brown (10YR 3/3) moist; moderate medium prismatic structure that parts to moderate medium subangular blocky; hard, friable, moderately sticky and moderately plastic; many fine roots; common fine pores; 15 percent pebbles; faint patchy clay films on peds and in pores; common fine pores; neutral (pH 7.0); gradual wavy boundary. (7 to 12 inches thick)
Bw--30 to 38 inches; grayish brown (2.5Y 5/2) gravelly loam, dark grayish brown (2.5Y 4/2) moist; weak fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common fine roots; thin patchy clay films on peds and in pores; common fine pores; 30 p;percent pebbles; neutral (pH 7.2); gradual wavy boundary. (5 to 10 inches thick)
Cd--38 to 60 inches; grayish brown (2.5Y 5/2) gravelly loam, dark grayish brown (2.5Y 4/2) moist; massive; hard, friable, moderately sticky and moderately plastic; few roots; many fine pores; 30 percent pebbles; slightly effervescent; slightly alkaline (pH 7.8).
TYPE LOCATION: Stevens County, Washington; about 2 miles northeast of Barstow; 400 feet east and 500 feet north of the southwest corner of sec. 11, T. 38 N., R. 37 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature at a depth of 20 inches ranges from 48 to 52 degrees F. These soils are usually moist but are dry in all parts between depths of 8 and 24 inches for 60 to 90 consecutive days following the summer solstice. The mollic epipedon is 20 to 40 inches thick. Solum thickness ranges from 25 to 40 inches. The upper 7 to 14 inches has an estimated moist bulk density of 1.15 to 1.35 g/cc, volcanic glass content of 5 to 20 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 0.4 to 1.0 percent, and 15-bar water retention of 5 to 10 percent for air dried samples. Depth to carbonates ranges from 25 to greater than 60 inches. The particle-size control section is 5 to 30 percent coarse fragments. Some pedons have a gravelly or stony surface layer.
The A horizon has value of 3 through 5 dry, 2 or 3 moist, and chroma of 1 through 3 dry or moist. Rock fragments range from 0 to 30 percent.
The Bw horizon has hue of 10YR or 2.5Y, value of 4 through 6 dry, 3 through 5 moist, and chroma of 2 through 4 dry or moist. It is silt loam, loam, gravelly silt loam, or gravelly loam and has weak to moderate structure. Coarse fragments range from 10 to 30 percent. In some pedons the BA and Bw horizons lack clay films.
The Cd horizon has hue of 10YR or 2.5Y, value of 4 through 7 dry, 3 through 5 moist, and chroma of 2 through 4 dry or moist. It is gravelly loam or gravelly sandy loam. This horizon is neutral or slightly alkaline. It is 15 to 35 percent rock fragments.
COMPETING SERIES: These are Conconully, Deno, Fanal, Phoebe, Safety, and Uhlig series. The Conconully soils are dry 90 to 105 consecutive days following the summer solstice. The Deno soils are deep to t lithic contact. Fanal, Phoebe, and Uhlig soils do not have a densic contact. The Safety soils are moderately deep to a paralithic contact.
GEOGRAPHIC SETTING: Stevens soils are on uplands at elevations of 1,600 to 3,000 feet. Slopes are 0 to 65 percent. These soils formed in glacial till of mixed mineralogy, including argillite, quartzite, and limestone with a component of loess and volcanic ash. They are in a continental climate. Mean annual temperature is 46 to 48 degrees F. Average annual precipitation is about 15 to 20 inches, and the frost-free season is 100 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cedonia, Dehart, Garrison, Hunters, Molcal, and Scoap soils and the competing Donavan soil. Cedonia and Hunters soils have a fine-silty control section. Dehart, Garrison, and Scoap soils have a loamy-skeletal control section. Molcal soils are calcareous and have a coarse-loamy control section.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Used for cropland, timber production and grazing, alfalfa hay, grass-legume hay, and small grains are common crops. The native vegetation is ponderosa pine and Douglas-fir with an understory of common snowberry, pinegrass, blue wildrye, creeping Oregon-grape, Saskatoon serviceberry, spreading sweetroot, and white stoneseed. These soils appear to have a forest potential; however, some areas that historically have been without trees occur. These areas are growing bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass, prairie junegrass, rose, and common snowberry.
DISTRIBUTION AND EXTENT: Northeastern Washington; Ferry and Stevens County. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Stevens County, Washington, 1913.
REMARKS: Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the mineral surface to 30 inches, a cambic horizon from 30 to 38 inches. Though the BA and Bw horizons have thin patchy clay films on peds and in pores, the increase in clay is not sufficient to constitute an argillic horizon. The base saturation (by sum of cations) is less than 75 percent in parts of the upper 75 cm of the soil. The description reflects a change in classification from coarse-loamy, mixed, mesic Vitrandic Haploxerolls to coarse-loamy, mixed, superactive, mesic Vitrandic Haploxerolls.
ADDITIONAL DATA: Laboratory data are available on this soil. Soil laboratory numbers; 69207-69212 and 69213-69218. Data supports classification change.