LOCATION OKANOGAN WA
The Okanogan series consists of deep, well drained soils formed in alluvium of mixed mineralogy. These soils are on flood plains, low stream terraces, and broad alluvial fans. Slopes are 0 to 5 percent. The mean annual precipitation is about 10 inches and the mean annual temperature is about 50 degrees F.
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Cumulic Haploxerolls
TYPICAL PEDON: Okanogan loam - in orchard. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 3 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, friable, nonsticky, slightly plastic; many roots; neutral (pH 7.0); clear smooth boundary. (2 to 10 inches thick)
A1--3 to 14 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak coarse granular structure; many roots; common fine and medium pores; worm castings in horizon; neutral (pH 7.0); gradual smooth boundary. (5 to 15 inches thick)
A2--14 to 31 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak medium prismatic structure; soft, very friable, nonsticky, slightly plastic; common roots; common fine and medium pores; neutral (pH 6.9); gradual wavy boundary. (0 to 20 inches thick)
AC1--31 to 45 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; common roots; common fine and medium pores; neutral (pH 6.80; abrupt wavy boundary. (10 to 20 inches thick)
AC2--45 to 48 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 3/3) moist; massive; slightly hard, friable, nonsticky, nonplastic; common roots; common fine and medium pores; slightly alkaline (pH 7.6); abrupt wavy boundary. (0 to 10 inches thick)
C--48 to 65 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable, nonsticky, nonplastic; common roots; slightly calcareous; moderately alkaline (pH 8.0).
TYPE LOCATION: Okanogan County, Washington; about 4 miles north of the town of Riverside, 1,100 feet west and 1,200 feet north of the southeast corner of sec. 5, T.35N., R.27E., WM (Latitude 48 degrees, 33 minutes, 24 seconds North, Longitude 119 degrees, 29 minutes, 09 seconds West NAD83).
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 51 to 55 degrees F. The moisture regime is xeric bordering on aridic. These soils are usually moist but are dry in all parts between depths of 8 and 24 inches for 90 to 105 consecutive days following the summer solstice. The particle-size control section is 15 to 30 percent sand coarser than very fine and 0 to 10 percent rock fragments. The mollic epipedon is 20 to more than 40 inches. Organic matter decreases irregularly with depth. Some pedons have secondary carbonates below a depth of about 44 inches.
The A horizon has value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3 dry or moist. Reaction is neutral or slightly alkaline.
The AC and C horizons have hue of 10YR or 2.5Y, value of 5 through 7 dry, 3 through 5 moist, and chroma of 2 or 3 dry, 2 through 4 moist. They are silt loam, loam, fine sandy loam, or sandy loam. The lower part of the C horizon in some pedons is stratified with lenses of sand 1/2 to 3 inches thick. Reaction is neutral to moderately alkaline.
COMPETING SERIES: These are the
Redola soils. Coxlake soils are dry in the moisture control section for 45 to 60consecutive days. Endersby soils are more than 30 percent sand coarser than very fine in the particle-size control section. Evans soils are slightly acid in the control section. Leavenworth and Patit Creek soils are dry in the moisture control section for 60 to 75 consecutive days. In addition, Patit Creek soils have more than 10 percent rock fragments in the particle- size control section. Narcisse soils are dry in the moisture control section for 60 to 80 consecutive days. Pleasant View soils are gravelly in the particle-size control section and have secondary lime in the Ck horizon. Poween soils are dry in the moisture control section for 75 to 90 consecutive days. Redola soils ar calcareous throughout.
GEOGRAPHIC SETTING: Okanogan soils are on flood plains, low stream terraces and broad alluvial fans. These soils formed in alluvium of mixed mineralogy. Elevations is 700 to 2,000 feet. The climate is characterized by warm, dry summers and cool, moist winters. The mean annual precipitation is 9 to 12 inches. The mean January temperature is about 25 degrees F, mean July temperature is about 74 degrees F, and the mean annual air temperature is about 50 degrees F. The frost-free season is 140 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Tonasket soils. Aeneas and Pogue soils are coarse-loamy over sandy or sandy- skeletal. Cashmere, Cashmont, and Tonasket soils have mollic epipedons less than 20 inches thick. Ellisforde soils are coarse-silty. Monse soils are fine-silty and are in the aquic subgroup. Quincy and Skaha soils lack a mollic epipedon. Strat soils are loamy-skeletal. In addition, all of these soils have a regular decrease in organic matter.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability.
USE AND VEGETATION: Principal uses are irrigated hay and pasture, irrigated orchards, irrigated and dryland cropland, and wildlife habitat. The native vegetation is basin wildrye, Reed canarygrass, sticky geranium, wood rose, Columbia hawthorn, black hawthorn, chokecherry, Saskatoon serviceberry, black cottonwood, and ponderosa pine.
DISTRIBUTION AND EXTENT: North central Washington. The series is of limited extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Okanogan County Area, Washington, 1972.
REMARKS: This draft reflects a change in classification from coarse-loamy, mixed, mesic Fluventic Haploxerolls to coarse-loamy, mixed, mesic Cumulic Haploxerolls. Diagnostic horizons and features recognized in this pedon are a mollic epipedon from the surface to 31 inches and an irregular decrease in organic carbon with depth (inferred from the stratified nature of the parent material).
National Cooperative Soil Survey