LOCATION WASSON OREstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid, mesic Fluvaquentic Humaquepts
TYPICAL PEDON: Wasson loam, on a 0 percent slope at an elevation of 40 feet. (Colors are for moist soil unless otherwise stated)
Oi--0 to 2 inches; duff layer of partially decomposed leaves.
A--2 to 10 inches; very dark grayish brown (2.5Y 3/2) loam, grayish brown (2.5Y 5/2) dry; moderate fine and medium granular and subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine, and many fine and medium roots; many fine irregular pores; common fine and medium distinct dark brown (7.5YR 3/4) masses of iron accumulation; moderately acid (pH 5.7); clear smooth boundary. (6 to 12 inches thick)
AC--10 to 14 inches; very dark grayish brown (2.5Y 3/2) very fine sandy loam, grayish brown (2.5Y 5/2) dry; weak fine and medium subangular blocky structure parting to weak fine granular; soft, very friable, slightly sticky and slightly plastic; common very fine, and many fine and medium roots; many fine tubular pores; many medium and coarse distinct dark brown (7.5YR 3/4) masses of iron accumulation; moderately acid (pH 5.6); clear smooth boundary. (0 to 6 inches thick)
Cg1--14 to 25 inches; very dark gray (5Y 3/1) loamy fine sand, light brownish gray (2.5Y 6/2) dry; massive; soft, very friable, nonsticky and nonplastic; few fine and common medium roots; few fine and common medium irregular pores; common medium and coarse prominent dark brown (7.5YR 3/4) masses of iron accumulation; strongly acid (pH 5.5); clear smooth boundary.
Cg2--25 to 45 inches; very dark gray (5Y 3/1) fine sandy loam, light brownish gray (2.5Y 6/2) dry; single grain; soft, very friable, nonsticky and nonplastic; common very fine and fine irregular pores; few fine faint dark yellowish brown (10YR 3/4) masses of iron accumulation; very strongly acid (pH 4.8); clear smooth boundary.
Cg3--45 to 54 inches; very dark gray (5Y 3/1) loamy fine sand, grayish brown (2.5Y 5/2) dry; single grain; soft, very friable, nonsticky and nonplastic; common very fine and fine irregular pores; very strongly acid (pH 4.8); clear smooth boundary.
Cg4--54 to 60 inches; very dark gray (5Y 3/1) fine sandy loam, grayish brown (2.5Y 5/2) dry; single grain; soft, very friable, nonsticky and nonplastic; common very fine irregular pores; very strongly acid (pH 4.8). (Combined thickness of the Cg horizon is 44 to 50 inches)
TYPE LOCATION: Douglas County, Oregon, near the confluence of Wasson Creek and Smith River, 2,175 feet north and 625 feet east of the S.W. corner of section 4, T. 21 S., R. 10 W. (Latitude 43 degrees, 46 minutes, 56 seconds N, Longitude 123 degrees, 54 minutes, 17 seconds W; North Fork, OR 7.5 minute USGS Quad; NAD 1927.)
RANGE IN CHARACTERISTICS: The soil is usually moist and is saturated with water during several months each year when not artificially drained. It is dry for a short period of less than 45 consecutive days between depths of 4 to 12 inches in the four month period following the summer solstice in most years. Depth to bedrock is greater than 60 inches. There is 0 to 5 percent gravel throughout the profile. The umbric epipedon is 10 to 14 inches thick. The particle-size control section has 5 to 10 percent clay and more than 15 percent fine sand or coarser. The mean annual soil temperature is 49 to 55 degrees F. In some pedons, there are thin strata of finer textures below a depth of 35 inches. Depth to redoximorphic concentrations ranges from near the surface to 10 inches, and occur throughout the profile.
The A horizon has hue of 2.5Y or 10YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It has masses of iron accumulation with having hue of 7.5YR or 5YR and chroma of 4 or more. It is loam with 7 to 15 percent clay.
The AC horizon, when present, has hue of 2.5Y or 10YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. Redoximorphic concentrations and matrix colors are similar to the A horizon. It is very fine sandy loam with 5 to 10 percent clay. Reaction is very strongly to moderately acid.
The Cg horizon has hue of 10YR to 5Y, value of 3 to 5 moist, 5 to 7 dry and chroma of 1 moist, 1 or 2 dry. The upper part contains iron accumulations having hue of 10YR to 5YR with chroma of 4 or more. It is a stratified very fine sandy loam to loamy fine sand with 5 to 10 percent clay. Reaction is very strongly to moderately acid with pH decreasing with depth.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Wasson soils occur in shallow swales and depressions on flood plains. Elevations are 20 to 1,200 feet. The soils formed in stratified recent alluvium derived from sandstone and siltstone. Slopes are 0 to 3 percent. The climate is characterized by warm, wet winters and hot, moist summers. The mean annual temperature is 48 to 54 degrees F. The mean annual precipitation is 60 to 100 inches. The frost free period is 140 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gardiner, Kirkendall, Meda, Natal, Nekoma, Quosatana and Wintley soils. Gardiner, Kirkendall and Nekoma soils are well drained and on planar or convex positions of flood plains. Meda soils are fine-loamy and occur on alluvial fans or toe slopes of mountains adjacent to flood plains or stream terraces. Natal soils are fine and on terraces. Quosatana soils are fine-silty and also occur in low or concave positions on flood plains. Wintley soils are fine textured, well drained, and occur on higher stream terraces.
DRAINAGE AND PERMEABILITY: Poorly drained; moderate permeability. A seasonal water table is at its uppermost limit from November through March and the soil is ponded from December to March. Wasson soils have an occasional flooding frequency for brief periods from November through March.
USE AND VEGETATION: The soils are used for watershed and wildlife habitat. Potential native vegetation is Oregon ash, red alder, willow, sedges, rushes and bentgrass.
DISTRIBUTION AND EXTENT: Flood plains along river valleys in the Coast Range Mountains of western Oregon; MLRA 1. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Douglas County, Oregon, 1994. The source of the name is taken from Wasson Creek, a tributary of the Smith River in Douglas County.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - from 2 to 14 inches (A and AC horizons)
Aquic feature - matrix color with chroma 2 or less below the umbric epipedon, and redox concentrations present (Cg1 horizon)
Fluvaquentic feature - irregular decrease in organic carbon content with increasing profile depth.
Soil reaction - pH of 5.6 from 8 to 12 inches (nonacid family)
Depth to diagnostic horizons and features is measured from the top of the first mineral horizon.
ADDITIONAL DATA: NSSL S82OR-019-005; type location, Douglas County, OR; NSSL, Lincoln, NE; 5/2000.