LOCATION CHETCO OREstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, nonacid, isomesic Fluvaquentic Humaquepts
TYPICAL PEDON: Chetco silt loam, grass-legume pasture, on a 2 percent planar slope at an elevation of 15 feet. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 8 inches; black (10YR 2/1) silt loam, gray (10YR 5/1) dry; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular pores; many fine distinct yellowish brown (10YR 5/6) masses of iron accumulation; strongly acid (pH 5.4); abrupt smooth boundary. (6 to 8 inches thick)
BA--8 to 12 inches; black (10YR 2/1) and dark grayish brown (10YR 3/2) silty clay loam, grayish brown (10YR 5/2) and gray (10YR 5/1) dry; moderate medium prismatic structure; hard, friable, sticky and plastic; many very fine roots; many very fine pores; few fine and medium black stains; common fine distinct masses of iron accumulation; strongly acid (pH 5.5); clear smooth boundary. (0 to 8 inches thick)
Bw1--12 to 22 inches; very dark gray (5Y 3/1) silty clay, gray (5Y 6/1, 5/1) dry; strong coarse prismatic structure; very hard, firm, very sticky and very plastic; many fine roots along prism faces; many fine pores; few faint clay films in pores; few fine black (2 to 5 millimeter) manganese concretions; many fine and medium distinct masses of iron accumulation; moderately acid (pH 6.0); clear smooth boundary.
Bw2--22 to 31 inches; dark gray (5Y 4/1) heavy silty clay loam, gray (5Y 6/1) dry; moderate very coarse prismatic structure; very hard, firm, sticky and plastic; many fine roots along prism faces; many very fine pores; few fine black (2 to 5 millimeter) manganese concretions; many fine and medium distinct masses of iron accumulation; slightly acid (pH 6.3); clear smooth boundary. (Combined thickness of the Bw horizon is 14 to 26 inches)
C1--31 to 54 inches; gray (5Y 5/1) sandy clay, gray (5Y 6/1) dry; massive; hard, firm, sticky and very plastic; few fine roots; many very fine tubular pores; many fine and medium distinct masses of iron accumulation; slightly acid (pH 6.4); clear wavy boundary (0 to 30 inches thick)
2C2--54 to 60 inches; olive gray (5Y 5/2) clay, light olive gray (5Y 6/2) dry; massive; hard, firm, very sticky and very plastic; many very fine tubular pores; many fine to coarse distinct masses of iron accumulation; slightly acid (pH 6.4).
TYPE LOCATION: Curry County, Oregon; about 1 mile west of Langlois; located about 2,100 feet north and 2,600 feet west of the southeast corner of section 34, T. 30 S., R. 15 W., W.M. (Latitude 42 degrees, 55 minutes, 53 seconds N.; Longitude 124 degrees, 27 minutes, 47 seconds W.)
RANGE IN CHARACTERISTICS: The soils are saturated during the winter season. The mean annual soil temperature is 51 to 54 degrees F. The difference between the mean summer and mean winter soil temperature is 5 to 9 degrees F. Soil depth is greater than 60 inches, but rooting depth is limited by the seasonal water table that ranges in depth from 0 to 18 inches. The umbric epipedon is 10 to 24 inches thick. Redox features range from few to many and faint to prominent in the A and Bw horizons and from none to many and faint to distinct in the C horizon. The particle-size control section averages 35 to 50 percent clay.
The A or Ap horizon has hue of 10YR or 2.5Y, value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 or 2 moist and dry. It is silt loam or silty clay loam with 20 to 35 percent clay. Soil reaction is slightly acid to strongly acid.
The Bw horizon has hue of 10YR through 5Y, value of 2 through 4 moist, 5 or 6 dry, and chroma of 1 or less moist and dry. It is light silty clay loam in the upper part and silty clay and heavy silty clay loam in the lower part. It is 27 to 50 percent clay. Soil reaction is moderately acid to slightly acid.
The C and 2C horizons have hue of 10YR through 5Y, value of 4 or 5 moist, 5 or 6 dry, and chroma of 1 or 2 moist and dry. It is clay loam, sandy clay, or clay. It has 35 to 50 percent clay. Thin lenses of sandier material are below 40 inches in some pedons.
COMPETING SERES: There are no other series in this family.
GEOGRAPHIC SETTING: Chetco soils are on nearly level flood plains and lowlands that are slightly above tidal overflow. Elevations are 0 to 40 feet above mean sea level. Slopes are 0 to 3 percent. The soils formed in silty marine alluvium in tidal flats. The climate is characterized by cool wet winters and cool moist summers with fog. The mean annual precipitation is 60 to 90 inches. The mean annual temperature is 50 to 53 degrees F. The average January temperature is 44 degrees F.; and the average July temperature is 59 degrees F. The frost-free period is 200 to 300 days. Chetco soils are on the Ingram geomorphic surface (stream environment) or the Tenmile surface (marine enviroment).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coquille, Langlois, and Nestucca soils. Coquille soils occur along tide-influenced flood plains, are fine-silty, and have moist chroma of 2 or more at a depth of 10 to 30 inches. Langlois soils occur on old tidal flats and flood plains, lack a Bw horizon, and have gleyed C horizons. Nestucca soils occur on flood plains above tidal overflow, are fine-silty, and are somewhat poorly drained.
DRAINAGE AND PERMEABILITY: Very poorly drained; very slow permeability. This soil is subject to frequent, long periods of flooding. A seasonal high water table is present at a depth of 0 to 1.5 feet from October to May.
USE AND VEGETATION: The soils are used for forage crops in native and improved pastures. The natural vegetation is mostly grasses, sedges, tussocks of grasses and sedges, Douglas iris, skunckcabbage, and scattered Sitka spruce, red alder, willow and Oregon ash.
DISTRIBUTION AND EXTENT: Southwestern Oregon coastal flood plains and lowlands; MLRA 1. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Curry County, Oregon, 1974.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Umbric epipedon - from the surface to 12 inches (Ap and BA horizons).
Cambic horizon - from 12 to 31 inches (Bw1 and Bw2 horizons).
Aquic feature - saturation to the surface and moist chroma of 2 or less below the umbric epipedon and within 20 inches (Bw1 horizon).
Nonacid feature - pH of 5.5 (H20 1:1) or more between 10 and 40 inches.
Particle-size control section - from 10 to 40 inches (part of BA horizon, Bw1, Bw2, and part of C1 horizon).