LOCATION NORTHRUP OREstablished Series
TAXONOMIC CLASS: Fine-silty, isotic, mesic Oxyaquic Haplohumults
TYPICAL PEDON: Northrup silt loam, pasture. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 6 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic, many fine and very fine roots; common medium vesicular pores; very strongly acid (pH 4.8); clear smooth boundary. (5 to 7 inches thick)
A--6 to 18 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots; common medium and fine irregular pores; very strongly acid (pH 4.6); clear wavy boundary. (5 to 13 inches thick)
Bt1--18 to 24 inches; yellowish brown (10YR 5/4) silty clay loam, light yellowish brown (10YR 6/4) dry; moderate medium prismatic structure; hard, friable, moderately sticky and moderately plastic; common fine roots; common very fine tubular pores; common faint clay films on peds; common very fine faint strong brown (7.5YR 5/8) redox concentrations; extremely acid (pH 4.4); clear wavy boundary. (6 to 12 inches thick)
Bt2--24 to 44 inches; pale brown (10YR 6/3) silt loam, very pale brown (10YR 7/4) dry; moderate fine subangular blocky structure; hard, friable to firm, moderately sticky and slightly plastic; few fine roots; many very fine tubular and common fine irregular pores; few faint clay films on peds and in pores; many very fine distinct yellowish red (5YR 5/8) redox concentrations;extremely acid (pH 4.4); gradual smooth boundary. (18 to 24 inches thick)
C--44 to 60 inches; light yellowish brown (10YR 6/4) silt loam, very pale brown (10YR 7/4) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine tubular pores; 30 percent soft gravel; many medium distinct strong brown (7.5YR 5/8) redox concentrations and light gray (10YR 7/2) redox depletions; extremely acid (pH 4.2).
TYPE LOCATION: Clatsop County, Oregon, about 1/2 mile west of Jewell road on a dead end road that junctions just north of the bridge across the Nehalem River, 200 feet north of road, southwest 1/4 southeast 1/4 southwest 1/4, sec. 21, T. 5 N., R. 7 W., Willamette Meridian.
RANGE IN CHARACTERISTICS: The soils are usually moist and they are dry for less than 45 consecutive days in all parts between 4 and 12 inches. The mean annual soil temperature is 50 to 54 degrees F. Depth to bedrock is greater than 60 inches. The umbric epipedon is 10 to 20 inches thick.
The A horizon has hue of 7.5YR or 10YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It has granular or subangular blocky structure. It averages 20 to 27 percent clay. It is very strongly to strongly acid.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 to 6 moist, 6 or 7 dry; and chroma of 3 or 4 moist and dry. It is silt loam or silty clay loam with 25 to 35 percent clay and less than 15 percent coarser than very fine sand. It is extremely to very strongly acid.
The C horizon has hue of 10YR or 2.5Y, value of 5 or 6 moist, 6 or 7 dry, and chroma of 3 or 4 moist and dry. It averages 20 to 25 percent clay. It has 0 to 30 percent soft gravel. It is extremely to very strongly acid.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Northrup soils are on inland terraces on the western side of the coast range at elevations of 400 to 600 feet. Slope is 0 to 20 percent. The soils formed in mixed alluvium. The climate is cool and wet during the winter and warm and moist during the summer. The mean annual temperature is 48 to 52 degrees F. The mean annual precipitation is 70 to 90 inches. The frost-free period is 145 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mayger and Rinearson soils. Mayger soils have a clayey subsoil. Rinearson soils are well drained and have siltstone of 40 to 60 inches depth.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow to medium runoff; moderately slow permeability.
USE AND VEGETATION: Northrup soils are used for pasture, homesites, recreation, woodland and wildlife habitat. Native vegetation is Douglas-fir, western hemlock, red alder, bigleaf maple, vine maple, western swordfern, salal, and red huckleberry.
DISTRIBUTION AND EXTENT: In the Coast Range of northwest Oregon. The series is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clatsop County, Oregon, 1984.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Umbric epipedon - the zone from 0 to 18 inches
Argillic horizon - the zone from 18 to 38 inches
Classification revised 09/02 from mixed mineralogy to isotic mineralogy.
Classification revised 9/03 from Typic Haplohumults to Oxyaquic Haplohumults.