LOCATION TOKUL WAEstablished Series
TAXONOMIC CLASS: Medial, amorphic, mesic Aquic Vitrixerands
TYPICAL PEDON: Tokul gravelly medial loam-forested. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
Oi--0 to 1 inch; forest litter of leaves and twigs.
0a--1 to 2 inches; black (l0YR 2/l) decomposed litter.
A--2 to 6 inches; dark brown (7.5YR 3/2) gravelly medial loam, yellowish brown (l0YR 5/4) dry; moderate medium granular structure; soft, very friable, slightly sticky and nonplastic, weakly smeary; common very fine, fine, medium, and few coarse roots; common very fine discontinuous pores; 5 percent medium rounded concretions; l0 percent pebbles; moderately acid (pH 5.8); abrupt wavy boundary. (l to 4 inches thick)
Bsl--6 to 9 inches; dark brown (7.5YR 4/4) gravelly medial loam, light brown (7.5YR 6/4) dry; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic, weakly smeary; common very fine, fine, medium, and few coarse roots; common very fine discontinuous pores; 5 percent fine and medium rounded concretions; l5 percent pebbles; slightly acid (pH 6.2); clear smooth boundary. (3 to l4 inches thick)
Bs2--9 to 17 inches; strong brown (7.5YR 5/6) gravelly medial loam, light yellowish brown (l0YR 6/4) dry; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic, weakly smeary; common very fine, fine, medium, and few coarse roots; common very fine discontinuous pores; 5 percent fine and medium rounded concretions; l5 percent pebbles; slightly acid (pH 6.2); clear smooth boundary. (3 to l5 inches thick)
Bs3--17 to 24 inches; dark yellowish brown (l0YR 4/4) gravelly medial loam, very pale brown (l0YR 7/4) dry; common medium distinct yellowish brown (l0YR 5/8) redox concentrations; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic, weakly smeary; few very fine, fine, medium and coarse roots; common very fine discontinuous pores; 3 percent fine rounded concretions; l0 percent cobbles and 20 percent pebbles; slightly acid (pH 6.2); abrupt smooth boundary. (5 to l2 inches thick)
BC--24 to 33 inches; light olive brown (2.5Y 5/4) gravelly medial fine sandy loam, pale yellow (2.5Y 8/4) dry; common fine distinct yellowish brown (l0YR 5/8) redox concentrations; massive; slightly hard, friable, slightly sticky and nonplastic, weakly smeary; few very fine, fine, medium and coarse roots; common very fine discontinuous pores; l percent fine irregular shaped concretions; 5 percent cobbles and 25 percent pebbles; moderately acid (pH 6.0); abrupt smooth boundary. (5 to l4 inches thick)
2Bsm--33 to 62 inches; dark grayish brown (2.5Y 4/2) gravelly sandy loam, light gray (2.5Y 7/2) dry; common medium distinct yellowish brown (l0YR 5/8) redox concentrations; massive; hard, extremely firm, weakly cemented extremely hard in place; 35 percent pebbles; a very thin (.55mm) discontinuous indurated layer on surface of horizon; moderately acid (pH 6.0).
TYPE LOCATION: Snohomish County, Washington; 2,200 feet east and l,050 feet north of southwest corner sec. 6, T. 28 N., R. 7 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 50 degrees F. These soils are usually moist, but are dry for 45 to 60 consecutive days in the moisture control section following the summer solstice in most years. Depth to the 2Bsm horizon is 20 to 40 inches. Depth to redox concentrations with depletions having chroma of 2 or less is 20 to 40 inches. Rock fragments in the particle-size control section average l5 to 35 percent. It is strongly acid to slightly acid throughout. Phosphate retention is 85 to 90 percent. Acid ovalate aluminum plus one-half the iron is 2.0 to 4.0. Moist bulk density is 0.6 to 0.9 grams per cubic centimeter. The 15-bar water on air dried samples is 12 to 15 percent. Base saturation by sum of bases is 5 to 15 percent. NaF is 9.5 to 11.5.
The A horizon has hue of l0YR or 7.5YR, value of 2 through 4 moist, 4 through 6 dry, and chroma of l through 3 moist or dry. Structure is weak medium, weak fine subangular blocky, or moderate medium granular. Some pedons have an E horizon.
The Bs horizon has hue of l0YR or 7.5YR, value of 3 through 6 moist, 4 through 7 dry, and chroma of 4 through 6 moist or dry. It is gravelly loam, gravelly silt loam, or gravelly fine sandy loam. This horizon has weak medium or weak fine subangular blocky structure. There are 0 to l0 percent concretions.
The BC horizon has hue of 2.5Y or 5Y, value of 4 through 6 moist, 5 through 8 dry, and chroma of 2 through 4 moist or dry, and has redox concentrations. It is gravelly fine sandy loam, or gravelly loam.
The 2Bsm horizon is dense glacial till cemented with a combination of iron, aluminum, and organic matter. Moist bulk density is 1.60 to 1.80 grams per cubic centimeter. Phosphate retention is 30 to 50 percent.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Tokul soils are on till plains and glacially modified hills and mountains. Slope is 0 to 90 percent. Elevation ranges from 200 to l,l00 feet. The soils formed in glacial till mixed with loess and volcanic ash in the solum. The mean annual precipitation is 45 to 70 inches The mean January temperature is 33 degrees F.; mean July temperature is 59 degrees F., and the mean annual temperature is 46 to 52 degrees F. The frost-free season is l40 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barneston, Pastik, Ragnar, and Winston soils. These soils lack ortstein and are more than 60 inches deep. Also, Barneston soils are sandy-skeletal. Pastik soils are coarse-silty.
DRAINAGE AND PERMEABILITY: Moderately well to somewhat poorly drained; slow to rapid runoff; moderate permeability above the pan and very slow in the pan. A perched water table is as high as 18 to 36 inches at times from November through May.
USE AND VEGETATION: Used mostly for timber production and pasture. Native vegetation is Douglas-fir, western hemlock, western redcedar, bigleaf maple, and red alder. Understory consists of western swordfern, salal, vine maple, huckleberry, trailing blackberry, Pacific trillium, western brackenfern, salmonberry, deerfern, ladyfern, and Oregon- grape.
DISTRIBUTION AND EXTENT: West slopes of the Cascade Mountains in Northwestern Washington. The soils are extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
ADDITIONAL DATA: S98WA-061-001
SERIES ESTABLISHED: King County, Washington, l943.
REMARKS: Diagnostic horizons and other features:
- All depths to diagnostic horizons and features are measured from the top of the first mineral horizon.
- Ochric epipedon
- Cambic horizon - from 6 to 33 inches
- Cemented pan at 33 inches
- Redox concentrations at 17 inches with aquic conditions (depletions with chroma of 2 and concentrations) at 33 inches
- Andic soil properties from 2 to 33 inches
The series needs review for udic vs. xeric soil moisture retime. This series is the designated state soil for Washington State.