LOCATION TONASKET WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Calcidic Haploxerolls
TYPICAL PEDON: Tonasket silt loam, cultivated. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 8 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium platy structure; soft, very friable, slightly sticky and slightly plastic; many roots; few fine and medium pores; neutral (pH 7.2); clear smooth boundary. (7 to 9 inches thick)
Bw1--8 to 15 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; many roots; few fine and medium pores; slightly alkaline (pH 7.4); clear smooth boundary. (8 to 12 inches thick)
Bw2--15 to 28 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; many roots; common fine, medium and coarse pores; slightly alkaline (pH 7.6); abrupt wavy boundary. (10 to 15 inches thick)
2Bk1--28 to 41 inches; light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common roots; common fine pores; discontinuous varves or plates 1/8 to 1/4 inch in thickness; calcareous; moderately alkaline (pH 8.4); clear smooth boundary. (10 to 15 inches thick)
2Bk2--41 to 65 inches; light gray (5Y 7/2) silt loam, olive gray (5Y 5/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few roots; common medium and coarse pores; discontinuous varves or plates 1/8 to 1/4 inch in thickness; many thin veins and splotches of secondary carbonate, calcareous; strongly alkaline (pH 8.6).
TYPE LOCATION: Okanogan County, Washington; NW1/4 SW1/4 NE1/4 NW1/4 section 14, T.30N., R.24E.
RANGE IN CHARACTERISTICS: Solum thickness is 15 to 21 inches. The mean annual soil temperature is 50 to 55 degrees F. The soils range from neutral to strongly alkaline, becoming more alkaline with depth. Depth to secondary carbonates is 25 to 36 inches. The control section is dominantly silt loam, and contains less than 18 percent clay, more than 15 percent coarser than very fine sand, and up to 10 percent rock fragments. The mollic epipedon is 7 to 10 inches thick.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3 dry or moist. It is fine sandy loam, very fine sandy loam, or silt loam. This horizon has weak medium platy, weak granular or weak subangular blocky structure.
The Bw1 horizon has value of 5 or 6 dry and 4 or 5 moist. It is loam, very fine sandy loam, or silt loam. It has weak or moderate subangular blocky or prismatic structure.
The Bw2 horizon has hue of 10YR or 2.5Y, value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 or 3 moist. It is very fine sandy loam or silt loam. This horizon has weak structure, or is massive. It is calcareous in some pedons.
The 2Bk horizon has hue of 10YR, 5Y or 2.5Y, value of 6 or 7 dry, 4 or 5 moist, and chroma of 2 or 3 dry or moist. It s dominantly silt loam but includes strata of fine sand, fine sandy loam, or very fine sandy loam. Few gravel and "float" rocks are present in some pedons.
COMPETING SERIES: These are the Blue Star, Courtrock, Era, Farrell, and Touhey series. Blue Star soils have 15 to 35 percent rock fragments in the control section. Era soils have 10 to 25 percent pumice throughout the solum. Courtrock soils have 20 to 35 percent rock fragments in the lower part of the control section. Farrell soils have 20 to 35 percent rock fragments in the lower part of the control section. Farrell soils have loam or sandy loam texture in the lower part of the control section and lack laminated sediments. Touhey soils have 15 to 35 percent rock fragments in the control section.
GEOGRAPHIC SETTING: These soils occupy nearly level to steep terraces at elevations of 700 to 1,500 feet. Slope gradients range form 0 to 45 percent. Tonasket soils formed in glacial lake deposits. The climate is semiarid. The mean annual temperature is 49 degrees F.; the average annual precipitation is 8 to 12 inches; and the frost free season is 145 to 178 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cashmont, Okanogan, and Cashmere soils. Cashmere soils lack lime in the control section. Cashmont soils have 15 to 35 percent fragments in the control section. Okanogan soils have an irregular decrease in organic matter.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability in the upper part of the profile and moderately slow permeability in the laminated materials.
USE AND VEGETATION: Irrigated orchard and hayland, dryland small grain, and range. Native vegetation is bluebunch wheatgrass, needleandthread grass, buckwheat, bitterbrush, big sagebrush, and balsam root.
DISTRIBUTION AND EXTENT: North central Washington. The Tonasket soils are of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Okanogan County, Washington, 1972.
REMARKS: The Tonasket soils were formerly classified as Brown soils.