LOCATION SILETZ OREstablished Series
TAXONOMIC CLASS: Medial over loamy, ferrihydritic over isotic, isomesic Typic Fulvudands
TYPICAL PEDON: Siletz medial silt loam on a 1 percent convex slope, pasture. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 7 inches; very dark brown (10YR 2/2) medial silt loam, grayish brown (10YR 5/2) dry; weak medium and fine subangular blocky structure parting to moderate very fine granular; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine roots; many very fine irregular pores; very strongly acid (pH 4.8); abrupt smooth boundary. (6 to 10 inches thick)
A--7 to 14 inches; very dark brown (10YR 2/2) medial silt loam, brown (10YR 5/3), dry; moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine roots; many very fine continuous tubular pores; very strongly acid (pH 4.8); clear smooth boundary. (6 to 12 inches thick)
Bw1--14 to 22 inches; brown (7.5YR 4/4) medial silt loam, light yellowish brown (10YR 6/4) dry; weak fine and moderate very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine roots; many very fine exped tubular pores; very strongly acid (pH 5.0); gradual smooth boundary. (0 to 10 inches thick)
Bw2--22 to 31 inches; dark brown (7.5YR 3/4) medial loam, very pale brown (10YR 7/4) dry; weak, medium, and moderate very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; few very fine roots; many very fine exped tubular pores; 5 percent fine gravel; very strongly acid (pH 4.8); gradual smooth boundary. (0 to 11 inches thick)
2Bw3--31 to 42 inches; brown (7.5YR 4/4) very fine sandy loam, very pale brown (10YR 7/4) dry; weak medium and fine subangular blocky structure, slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine exped tubular pores; 5 percent fine gravel; very strongly acid (pH 4.6); abrupt smooth boundary. (7 to 22 inches thick)
2C1--42 to 55 inches; variegated, dark yellowish brown (10YR 3/4, 4/4) and very dark grayish brown (10YR 3/2) extremely gravelly loamy sand, yellowish brown (10YR 5/4) dark yellowish brown (10YR 4/6) and dark brown (10YR 3/3) dry; single grain; loose, nonsticky and nonplastic; few very fine roots; many fine irregular pores; 65 percent fine and very fine gravel; very strongly acid (pH 4.8); abrupt smooth boundary. (0 to 15 inches thick)
3C2--55 to 63 inches; dark yellowish brown (10YR 4/6) fine sandy loam, light yellowish brown (10YR 6/4) dry; massive, slightly hard, friable (weakly brittle), slightly sticky and plastic; few very fine roots; many very fine irregular pores; 5 percent fine gravel; very strongly acid (pH 5.0).
TYPE LOCATION: Lincoln County, Oregon, about 60 feet west of a buried cable junction box south of the turn in the driveway in the NE1/4 SW1/4 NW1/4 section 33, T. 9 S, R. 9 W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 48 to 54 degrees F. The difference between mean summer and mean winter soil temperature is 5 to 9 degrees F. under a tree canopy. These soils are usually moist, but have a short dry period of less than 45 days following the summer solstice. Depth to bedrock is over 60 inches. Thickness of the andic soil property materials and depth to the 2B horizon is 19 to 40 inches. The andic soil material has a phosphate retention of 95 to 100 percent, Alox + Feox of 3.0 to 5.0 percent, moist bulk density of 0.75 to 0.85 g/cc, and 15-bar moisture of 20 to 35 percent. The particle-size control section average less than 35 percent rounded rock fragments and 10 to 35 percent clay by field estimate. The umbric epipedon ranges from 12 to 20 inches. Reaction is very strongly or strongly acid throughout.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It has 10 to 25 percent clay, 0 to 5 percent rounded gravel, and 10 to 15 percent organic matter.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 4 to 7 dry, and chroma of 4 through 6 moist and dry. Texture is medial loam or medial silt loam It has 10 to 27 percent clay and 0 to 15 percent rounded gravel.
The 2Bw or 3BC horizon, when present, has hue of 10YR or 7.5YR, value of 3 or 4 moist, 4 through 7 dry and chroma of 4 through 6 moist and dry. Texture is fine sandy loam, very fine sandy loam, clay loam, or silty clay loam. It has 10 to 35 percent clay and 0 to 15 percent rounded gravel.
The 2C, 3C, or 4C horizon, when present, has hue of 10YR or 7.5YR, value of 3 through 6 moist and dry, and chroma of 2 through 6 moist and dry, and is variegated in some pedons. Texture is loamy sand, sand, sandy loam, or fine sandy loam. It has 5 to 15 percent clay, 0 to 75 percent rounded gravel, and 0 to 10 percent rounded cobbles.
COMPETING SERIES: This is the Tolovana series. The Tolovana soils have an umbric epipedon more than 20 inches thick and have angular shaped rock fragments.
GEOGRAPHIC SETTING: Siletz soils are on stream terraces at elevations of 50 to 400 feet. Slopes are 0 to 7 percent. They formed in silty over loamy alluvium of predominantly igneous origin. The climate is characterized by cool wet winters and cool moist summers. The mean annual precipitation is 70 to 100 inches. The mean annual temperature is about 49 to 52 degrees F. The mean January temperature is about 40 degrees F. and the mean July temperature is about 62 degrees F. The frost-free period is 160 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Knappa, Quillamook, and Wolfer soils. Knappa soils have an umbric epipedon 20 to 30 inches thick, have a fine-silty particle-size family class, and are on a higher terrace. Quillamook soils have a medial particle-size family class, have a melanic epipedon, and and are on a slightly higher terrace. Wolfer soils have a medial over sandy or sandy-skeletal particle-size family class and are on a higher terrace.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is moderate in the solum and rapid to moderate in the substratum.
USE AND VEGETATION: Most areas are cleared and used for cropland, pasture, homesites, and wildlife. Native vegetation is Douglas fir, western hemlock, bigleaf maple, Sitka spruce, red alder, western swordfern, and snowberry.
DISTRIBUTION AND EXTENT: River terraces of Winkle (Tenmile) age geomorphic surface in the central and northern Coast Range in Oregon; MLRA 4A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lincoln County, Oregon, 1990.
REMARKS: Diagnostic horizons and features in this pedon are:
Umbric epipedon - the zone from the surface of the soil to a depth of 14 inches. (Ap, A horizons)
Cambic horizon - the zone from 14 to 42 inches. (Bw1, Bw2, 2Bw3 horizons)
Particle-size control section - the zone from 0 to 40 inches of which 0 to 31 inches qualify as medial and 31 to 40 inches qualify as loamy.
Andic properties - The profile, to a depth of 31 inches (Ap, A, Bw1, and Bw2 horizons)
Classification revised 10/05 from Melanudands to Fulvudands. Value and Chroma, moist, overlap Melanudands and Fulvudands criteria for color. The Melanic Index based on laboratory data from similar soils is 1.75 to 2.0.