LOCATION YAKIMA WA+OREstablished Series
The Yakima series consists of very deep, well drained soils formed in alluvium. These soils are on bottomlands. Slopes are 0 to 3 percent. The mean annual precipitation is about 11 inches and the meanannual temperature is about 52 degrees F.
TAXONOMIC CLASS: Coarse-loamy over sandy or sandy-skeletal, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Yakima silt loam - pasture. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 8 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, friable, nonsticky and nonplastic; many fine and medium roots; 10 percent basalt gravel; slightly acid (pH 6.4); abrupt smooth boundary.
A1--8 to 22 inches; grayish brown (10YR 5/2) gravelly silt loam, very dark grayish brown (10YR 3/2) moist; massive; slightly hard, friable, nonsticky and nonplastic; common fine and medium roots; common fine pores; 15 percent coarse basalt gravel; neutral (pH 6.6); gradual wavy boundary.
A2--22 to 30 inches; grayish brown (10YR 5/2) gravelly silt loam, very dark grayish brown (10YR 3/2) moist; massive; slightly hard, friable, nonsticky and nonplastic; common medium roots; 30 percent coarse basalt gravel; neutral (pH 7.0); clear wavy boundary. (Combined thickness of the A horizon is 20 to 40 inches)
2C--30 to 60 inches; grayish brown (10YR 5/2) extremely gravelly sand, very dark grayish brown (10YR 3/2) moist; single grain; loose; 65 percent basalt gravel; neutral (pH 7.0)
TYPE LOCATION: Columbia County, Washington; 256 feet west of Milepost 1.29, U.P.R.R., and 20 feet south of fence; NE1/4 SW1/4, section 3, T. 12 N., R. 37 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 49 to 56 degrees F. The soils are usually dry. They are dry for one-half to three-fourths of the time when the soil temperature is above 41 degrees F. The mollic epipedon is 20 to 40 inches in thickness. The upper part of the particle-size control section averages 5 to 10 percent clay and 0 to 35 percent coarse fragments. The lower part of the particle-size control section is sand or loamy sand and averages 50 to 75 percent rock fragments. Depth to the 2C horizon is 20 to 40 inches. Reaction is slightly acid to slightly alkaline.
The A horizon has value of 4 or 5 dry, 2 or 3 moist and chroma of 1, 2, or 3 dry or moist. Texture of the fine-earth fraction is loam, sandy loam, silt loam or very fine sandy loam with 0 to 35 percent rock fragments.
The 2C horizon is sand, coarse sand or loamy sand in the fine-earth fraction and is very gravelly or extremely gravelly.
Some pedons have a weak B horizon or a C1 horizon.
COMPETING SERIES: These are the Dryck and Veazie series. Dryck soils have 12 to 18 percent clay in the upper part of the particle-size control section. Veazie soils have a xeric soil moisture regime.
GEOGRAPHIC SETTING: Yakima soils are in valley bottomlands along streams. Elevation is 500 to 2,000 feet. Slopes are 0 to 3 percent. These soils formed in alluvium derived from loess and basalt and overlie material that is mostly basaltic gravel and sand. The mean annual precipitation is 9 to 14 inches. The average January temperature is 33 degrees F. and the average July temperature is 74 degrees F.. The mean annual temperature is 48 to 55 degrees F. The frost-free season is 100 to 195 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Esquatzel, Farrell, Kuhl, Logy, Ritzville, Roloff, Simcoe, Stanfield, and Umapine soils. Esquatzel, Farrell, and Simcoe soils lack strongly contrasting textures in the particle-size control section. Kuhl soils have bedrock at a depth of 10 to 20 inches. Ritzville soils are coarse-silty. Roloff soils have bedrock at a depth of 20 to 40 inches. Stanfield soils have a duripan at a depth of 20 to 40 inches. Umapine soils are very strongly alkaline and calcareous throughout. Logy soils are loamy-skeletal and have a mollic epipedon less than 20 inches thick.
DRAINAGE AND PERMEABILITY: Well-drained; very slow to slow runoff; moderate permeability above the 2C horizon and very rapid permeability to the 2C horizon.
USE AND VEGETATION: These soils are used mainly for irrigated cropland. Alfalfa, grass, and vegetables are common crops. Native vegetation is bluebunch wheatgrass, basin wildrye, sagebrush, and some cottonwood and willows.
DISTRIBUTION AND EXTENT: Eastern Oregon and Washington; MLRA 7, 8, and 10. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yakima County, Washington, 1901.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon the zone from 0 to 30 inches
Particle-size control section the zone from 10 to 40 inches with 10 to 30 inches qualifying as coarse-loamy and from 30 to 40 inches qualifying as sandy-skeletal
Lithologic discontinuity to sand and gravel at 30 inches.
Soil moisture regime aridic bordering xeric based on precipitation and geographically associated soils