LOCATION SCOON WA+IDEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, mesic, shallow Xeric Haplodurids
TYPICAL PEDON: Scoon silt loam - irrigated. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 6 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; 5 percent pebbles; slightly alkaline (pH 7.8); abrupt smooth boundary. (3 to 7 inches thick)
Bw--6 to 10 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; weak coarse prismatic structure; slightly hard, friable, slightly sticky and slightly plastic; few roots; few fine tubular pores; 10 percent pebbles; moderately alkaline (pH 8.2); gradual wavy boundary. (3 to 7 inches thick)
Bk--10 to 16 inches; light brownish gray (10YR 6/2) gravelly silt loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; few fine tubular pores; 30 percent pebbles; violently effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (0 to 6 inches thick)
2Bqkm--l6 inches; indurated lime-silica duripan.
TYPE LOCATION: Yakima County, Washington; 3/4 mile north of Williamson Road and 100 feet west of Washout Road in the NE1/4NE1/4 sec. 36, T. 11 N., R. 22 E., W.M.
RANGE IN CHARACTERISTICS: These soils are dry more than one-half the time the soil temperature is above 41 degrees F (about 105 to 130 days), but are moist in winter and early spring. Depth to the duripan is 10 to 20 inches. The mean annual soil temperature is 52 to 56 degrees F. The particle-size control section averages 10 to 35 percent rock fragments, 5 to 18 percent clay and 30 to 60 percent sand most of which is fine or very fine sand size. Rock fragments consists mostly of basalt and indurated duripan fragments. The duripan is 4 inches to several feet thick and overlies weakly consolidated gravel and sand alluvial deposits or weakly consolidated lacustrine deposits or overlying basalt at 30 or more inches. Depth to secondary carbonates when present is 10 to 14 inches.
The A horizon has value of 5 to 7 dry, 3 to 5 moist, chroma of 2 or 3 moist and dry. It is neutral to moderately alkaline.
The Bw horizon has value of 6 or 7 dry, 4 or 5 moist and chroma of 2 to 4 dry or moist. It is loam, silt loam, or very fine sandy loam and can be gravelly. It is slightly alkaline or moderately alkaline.
The Bk horizon has value of 6 or 7 dry, 4 or 5 moist, and chroma of 2 or 3 moist and dry. It is silt loam, loam, fine sandy loam, or very fine sandy loam and has 10 to 35 percent coarse fragments, mostly pebbles. When present, it has 5 to 30 percent calcium carbonate.
COMPETING SERIES: These are the Arritola (T), Besslen, Chiara, Coltroop, Frohman, Minveno, Nevoyer, Otoole, Peeko, Plegomir, Tenvorrd, Truvar, and Yahoo series. Arritola soils 25 to 35 percent clay. Besslen soils have a calcic horizon with over 15 percent calcium carbonate and have a mean annual soil temperature of 49 to 53 degrees F. Chiara soils have less than 15 percent fine sand and coarser, and are virtually free of rock fragments above the duripan. Frohman soils have less than 10 percent rock fragments in the Bk Horizon. Minveno and Yahoo soils have less than 15 percent very fine sand or coarser and less than 10 percent coarse fragments. Nevoyer soils have a lithic contact at a depth of less than 20 inches. Otoole soils are somewhat poorly drained, and have a high exchangeable sodium content. Peeko and Plegomir soils lack a Bw horizon, have 18 to 27 percent clay and have a mean annual soil temperature of 47 to 53 degrees F. Tenvorrd soils are 18 to 25 percent clay and less than 5 percent rock fragments in the particle-size control section. Yahoo soils have 20 to 30 percent clay in the particle-size control section. Truvar soils have a strongly cemented duripan and have 50 to 70 percent medium and coarse sand in the particle-size control section. Coltroop soils have 20 to 30 percent clay in the particle-size control section and have a mean annual soil temperature of 47 to 52 degrees F.
GEOGRAPHIC SETTING: Scoon soils are on uplands and terraces at elevations from 800 to 2,300 feet in Washington and 2,600 to 4,900 feet in Idaho. Slopes are 0 to 30 percent. The soils formed in loess and silty alluvium mantling a duripan. They are in an arid climate with hot, dry summers and cool, moist winters. The mean annual precipitation is 6 to 12 inches. The mean annual temperature is 49 to 53 degrees F. The frost-free season is 135 to 210 days in Washington and 100 to 140 days in Idaho.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Burke, Roza, Shano, Starbuck, and Taunton soils. Burke soils on uplands and Taunton soils on terraces have a duripan at a depth of 20 to 40 inches. Burke soils are coarse-silty. Roza soils on old alluvial fans, Shano, and Starbuck soils lack a duripan. Also, Shano soils on uplands are coarse-silty and Starbuck soils on benches and hillslopes have a lithic contact at 10 to 20 inches.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability above the duripan.
USE AND VEGETATION: Irrigated cropland and range. Native vegetation on silt loam and loam is bluebunch wheatgrass, Sandberg bluegrass, and big sagebrush. Sandy loam range sites are Thurber needlegrass and Indian ricegrass.
DISTRIBUTION AND EXTENT: South-central Washington and southern Idaho. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Cassia County, Idaho, 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon, a cambic horizon from 6 to 10 inches, a zone of secondary carbonate accumulation from 10 to 16 inches, and a duripan at 16 inches.