LOCATION DUPONT WAEstablished Series
TAXONOMIC CLASS: Diatomaceous, euic, mesic Limnic Haplosaprists
TYPICAL PEDON: Dupont muck - pasture (Colors are for moist soil unless otherwise noted.)
Oa--0 to 13 inches; black (5YR 2/1 rubbed) muck, black (10YR 2/1) dry; about 20 percent fibers, less than 5 percent rubbed; moderate fine subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; many roots; very strongly acid (pH 5.0 in H20); abrupt smooth boundary. (12 to 15 inches thick)
2Ldi--13 to 16 inches; dark reddish brown (5YR 3/4) diatomaceous earth and volcanic ash, strong brown (7.5YR 5/6) dry; moderate fine prismatic structure; slightly hard, very friable, nonsticky, nonplastic; common roots; very strongly acid (pH 5.0 in H2O); abrupt smooth boundary. (2 to 10 inches thick)
3O'a1--16 to 46 inches; black (5YR 2/1 rubbed) muck, 30 percent fibers, 5 percent rubbed; moderate medium subangular blocky structure; slightly hard, very friable, nonsticky, nonplastic; common roots; very strongly acid (pH 4.8 in H2O); clear wavy boundary. (28 to 36 inches thick)
3O'a2--46 to 72 inches; black (5 YR 2/1 rubbed) muck, 40 percent fibers, about 5 to 10 percent rubbed; massive; slightly hard, very friable, nonsticky, nonplastic; very few roots; strongly acid (pH 5.4 in H2O).
TYPE LOCATION: Pierce County, Washington; 860 feet west and 1,320 feet south of the NE corner sec. 35, R. 20 N., R. 2 E.
RANGE IN CHARACTERISTICS: Organic material ranges in thickness from 52 inches to more than 10 feet. Depth to the limnic materials is 7 to 24 inches near the perimeter of most bogs and 24 to 50 inches near the center. These soils are mostly decomposed materials from spirea, sedges, and grasses. The control section is sapric material with an unrubbed fiber content of 20 to 40 percent and a rubbed fiber content from 10 to less than 5 percent. The limnic materials are diatomaceous earth and are generally mixed with volcanic ash and are 2 to 10 inches thick. Some pedons have more than one layer of limnic material. The limnic materials have hue of 5YR, 7.5YR, 10 YR, or 2.5YR, value of 3 through 8 and chroma of 0 through 4. The tiers have hue of 5YR or 10YR. The soils are strongly or very strongly acid.
COMPETING SERIES: These are the Mukilteo, Orcas, Seattle, Semiahmoo, Shalcar, Tanwax, and Tukwila series in other families. Mukilteo and Seattle soils have control sections of hemic material. Orcas soils have fibric material in the control section. Semiahmoo soils lack limnic layers within the control section. Shalcar soils are muck over loamy mineral layers within the control section. Tanwax soils are medial and composed of sedimentary peat. Tukwila soils are dysic.
GEOGRAPHIC SETTING: Dupont soils are in depressions or basins in the glaciated uplands at elevations ranging from 150 to 1000 feet. these soils occur in a mild humid climate having an average annual precipitation of 30 to 70 inches. Mean January temperature is 40 degrees F.; mean July temperature is 57 degrees F.; and mean annual temperature is 50 degrees F. The frost-free season is 150 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alderwood, Bellingham, Everett, Kapowsin, Kitsap, Spanaway, an Tisch soils. All these soils are mineral soils. Tisch soils are medial an formed in volcanic ash.
DRAINAGE AND PERMEABILITY: Very poorly drained; surface runoff ponded; moderately slow permeability.
USE AND VEGETATION: Dupont soils are cleared and drained and used for growing blueberries, has and pasture, and undrained areas are used as wildlife habitat. Original vegetation was mainly Douglas spirea, sedges, reeds, and mosses.
DISTRIBUTION AND EXTENT: This series is of small extent in the puget lowlands of western Washington.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Pierce County, Washington, 1945.