LOCATION NEHALEM OR
Established Series
Rev. JAS/AON/RWL
06/2011
NEHALEM SERIES
The Nehalem series consists of very deep, well drained soils formed in mixed alluvium. Nehalem soils are on flood plains. Slopes are 0 to 3 percent. The mean annual precipitation is about 90 inches and the mean annual temperature is about 50 degrees F.
TAXONOMIC CLASS: Fine-silty, mixed, superactive, isomesic Fluventic Humudepts
TYPICAL PEDON: Nehalem silt loam, on a 1 percent slope at an elevation of 15 feet in pasture. When described on August 1, 1995, the soil was moist throughout. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; very dark grayish brown (10YR 3/2) silt loam, brown (10YR 5/3) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; moderately acid (pH 5.8); clear smooth boundary.
A--9 to 16 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate fine and very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; moderately acid (pH 5.8); clear smooth boundary. (Combined thickness of the A horizon is 10 to 20 inches)
Bw--16 to 48 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; moderately acid (pH 6.0); gradual smooth boundary. (14 to 40 inches thick)
BC--48 to 60 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; weak fine and medium subangular blocky structure, slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; moderately acid (pH 6.0).
TYPE LOCATION: Tillamook County, Oregon; located about 900 feet North of the Kilchis River; about 2,200 feet north and 1,700 feet west of the southeast corner of section 12, T. 1 S., R. 10 W.; USGS Tillamook topographic quadrangle (Latitude 45 degrees, 29 minutes, 55 seconds N. and Longitude 123 degrees, 50 minutes, 55 seconds W.)
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 49 to 55 degrees F. The difference between the mean summer and the mean winter soil temperature varies from 5 to 9 degrees F. The soil is usually moist and is dry in all parts between depths of 4 and 12 inches for a period of less than 45 consecutive days. Faint redox concentrations are below a depth of 20 inches in some pedons. The umbric epipedon is 10 to 20 inches thick. Depth to bedrock is more than 60 inches. The particle-size control section has 18 to 35 percent clay and less than 15 percent coarser than very fine sand. Lenses of coarser textured material are in some pedons.
The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It has 15 to 25 percent clay.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 5 or 6 dry, and chroma of 3 to 6 moist and dry. It is silt loam or silty clay loam with 18 to 35 percent clay.
The BC horizon, when present, is similar to the Bw horizon. It has 18 to 35 percent clay.
The C horizon, when present, is loam, silt loam, or silty clay loam with 18 to 35 percent clay. It has 0 to 15 percent rock fragments. In some areas, texture is very fine sandy loam or fine sandy loam below a depth of 40 inches with 12 to 20 percent clay.
COMPETING SERIES: There are no other series in this family. The
Nestucca series is similar. Nestucca soils are somewhat poorly drained and have distinct or prominent redox concentrations in the subsoil.
GEOGRAPHIC SETTING: Nehalem soils are on flood plains at elevations of 10 to 750 feet. Slopes are 0 to 3 percent. The soils formed in medium and moderately fine textured mixed alluvial materials. The climate is humid, characterized by cool, wet winters and cool, moist summers with fog. The mean annual temperature is 48 to 53 degrees F. The mean annual precipitation is 60 to 100 inches. The frost-free period is 160 to 300 days. Nehalem soils occur on the Ingram geomorphic surface.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Brenner,
Coquille,
Gauldy and
Nestucca soils. Brenner and Coquille soils are poorly and very poorly drained respectively. Gauldy soils are coarse-loamy over sandy or sandy-skeletal. These soils are on stream terraces.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability. Nehalem soils are subject to frequent or occasional flooding for brief periods.
USE AND VEGETATION: Nehalem soils are used for hay, pasture, and silage. Native vegetation is Douglas-fir, western hemlock, Sitka spruce, red alder, vine maple, swordfern and grasses.
DISTRIBUTION AND EXTENT: Flood plains of coastal river valleys in Western Oregon and Washington; MLRA 4A. The soil is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Astoria Area, Clatsop County, Oregon, 1942.
REMARKS: Diagnostic horizons and features of this pedon include:
Umbric epipedon - from surface to 16 inches (Ap and A horizons).
Cambic horizon - from 16 to 60 inches.
Particle-size control section - from 10 to 40 inches.
ADDITIONAL DATA: Chemical characterization data for one pedon, S68Oreg-20-5-1 through 6, from Oregon State University.
National Cooperative Soil Survey
U.S.A.