LOCATION WOODBURN OREstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquultic Argixerolls
TYPICAL PEDON: Woodburn silt loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 9 inches; very dark brown (10YR 2/2) silt loam, brown (10YR 5/3) dry; cloddy, with very weak subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; many very fine and fine tubular pores; few fine irregular pores; common medium and fine reddish brown and black concretions; moderately acid (pH 5.9); abrupt smooth boundary. (6 to 10 inches thick)
A--9 to 17 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many roots; many very fine, fine, and few medium tubular pores; common silt and sand grains on faces of peds; few thin darker colored very dark brown (10YR 2/2) coatings on faces of peds; few reddish brown and black concretions; slightly acid (pH 6.2); clear smooth boundary. (3 to 18 inches thick)
2Bt1--17 to 25 inches; dark yellowish brown (10YR 3/4) silty clay loam, brown (7.5YR 5/4) dry; moderate coarse and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common roots; many very fine and few fine tubular pores; few faint clay films on faces of peds; few reddish brown and black concretions; few black stains on peds; moderately acid (pH 6.0); clear smooth boundary. (7 to 12 inches thick)
2Bt2--25 to 32 inches; brown (7.5YR 4/4) silty clay loam, brown (10YR 5/3) dry; moderate medium and coarse subangular blocky structure; hard, friable, brittle, moderately sticky and moderately plastic; common roots; many very fine and few fine tubular pores; many distinct clay films on faces of peds and along pores; few fine and medium distinct iron depletions, dark gray (10YR 4/1) and light brownish gray (10YR 6/2) dry; few fine black concretions and stains on faces of peds; moderately acid (pH 5.8); abrupt smooth boundary. (6 to 17 inches thick)
2BCt1--32 to 39 inches; brown (10YR 4/3) silt loam, brown (10YR 5/3) dry; massive but some planes of weakness that are indistinct, vertical planes are more distinct than horizontal planes; very hard, very firm, brittle, slightly sticky and slightly plastic; few roots; many very fine and fine tubular pores; many distinct clay films on faces of peds and along some root channels and pores; few fine and medium black concretions and few black coatings on faces of peds; faint dark grayish brown (10YR 4/2) iron depletions in a few root channels, faint dark grayish brown (10YR 4/2) coating on plane surfaces, light gray (10YR 7/2) dry; moderately acid (pH 5.7); gradual smooth boundary. (6 to 20 inches thick)
2BCt2--39 to 54 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; massive; with some indistinct vertical planes of weakness; very hard, very firm, brittle, slightly sticky and slightly plastic; many very fine and fine tubular pores; many faint clay films along pores and old root channels; few black concretions and few coatings on faces of peds; moderately acid (pH 5.9); gradual wavy boundary. (0 to 17 inches thick)
2C1--54 to 68 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; massive; very hard, very firm, brittle slightly sticky and slightly plastic; many very fine tubular pores; common distinct clay films along the larger pores and old root or worm channels; few black coatings in pores and channels; moderately acid (pH 5.9); gradual wavy boundary. (14 to 30 inches thick)
2C2--68 to 80 inches; brown (10YR 4/3) very fine sandy loam, pale brown (10YR 6/3) dry; massive very hard, firm, slightly sticky and slightly plastic; many very fine pores; few faint clay films along the larger pores; few small black stains and coatings along pores and channels; moderately acid (pH 6.0); abrupt wavy boundary. (0 to 14 inches thick)
3C3--80 to 92 inches; brown (10YR 4/3) fine sandy loam, pale brown (10YR 6/3) dry; single grain; loose, friable; many fine irregular pores; moderately acid (pH 6.0).
TYPE LOCATION: Marion County, Oregon; about 200 feet west of paved road to Champoeg; SW1/4 SE1/4 section 2, T. 4 S., R. 2 W. Willamette Meridian. St. Paul, Oregon USGS topographic quadrangle. Latitude 45 degrees, 14 minutes, 25 seconds N.; Longitude 122 degrees, 53 minutes, 21 seconds W. NAD 27.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry in all parts between depths of 4 and 12 inches for 45 to 80 consecutive days during the summer. The mean annual soil temperature is 52 to 55 degrees F. The soils are more than 60 inches deep. The mollic epipedon is 10 to 20 inches thick. Depth to aquic conditions with chroma of 2 or less with or without redox concentrations is 20 to 30 inches. There are few to common, fine reddish brown or black concretions 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 weak to moderate granular ore subangular blocky structure. Texture is silt loam with 15 to 25 percent clay. It has 0 to 3 percent gravel. Reaction is strongly acid to slightly acid.
The AB or BA horizons, when present, have value of 4 or 5 dry and chroma of 2 or 3 moist and dry. They have weak or moderate prismatic or subangular blocky structure. Texture is silt loam in the upper part and silt loam or silty clay loam in the lower part with 20 to 35 percent clay. Reaction is strongly acid to slightly acid.
The 2Bt horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 5 or 6 dry and chroma of 3 or 4 moist and dry. It has weak to moderate prismatic or subangular blocky structure. Texture is loam or silty clay loam with 20 to 35 percent clay. Reaction is moderately acid or slightly acid.
The 2BCt horizon has value of 3 or 4 moist, 5 or 6 dry and chroma of 3 or 4 moist and dry. It has weak prismatic or subangular blocky structure or is massive. Texture is silt loam or silty clay loam with 20 to 35 percent clay. Reaction is moderately acid to neutral.
The 2C horizon has value of 4 or 5 moist, 5 or 7 dry and chroma of 3 or 4 moist and dry. It has weak prismatic or subangular blocky structure or is massive. Texture is silt loam or silty clay loam in the upper part and stratified silt loam, very fine sandy loam, loam, or fine sandy loam in the lower part. It has 10 to 30 percent clay. Reaction is moderately acid to neutral.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Woodburn soils are on nearly level to gently sloping broad valley terraces formed in indistinctly stratified alluvium or lacustrine Willamette silt of upper Pleistocene age. The soils are at elevations of 150 to 400 feet above sea level. Slopes are 0 to 55 percent. The climate is composed of warm, dry summers, and cool, moist winters. The mean annual precipitation is 40 to 50 inches. The mean annual temperature is 50 to 54 degrees F. The mean January temperature is 39 to 40 degrees F. and the mean July temperature is 65 to 67 degrees F. The frost-free period is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Amity, Aloha, Concord, Dayton and Willamette soils. Aloha soils do not have a mollic epipedon or an argillic horizon and are on terraces. Amity soils have an albic horizon, aquic conditions with chroma of 2 or less at a depth of 10 to 20 inches, and occur in depressions or on less sloping position on terraces. Concord and Dayton soils have aquic conditions with chroma of 2 or less at a depth of 0 to 10 inches. In addition, Concord is fine and Dayton has an abrupt textural change from the E to 2Bt horizons. They occur in depressions on terraces. Willamette soils lack aquic conditions and chroma of 2 or less within 40 inches of the surface.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow to medium runoff; moderately slow permeability. An apparent water table is at its uppermost limit from December to March.
USE AND VEGETATION: This series is used for growing berries, orchards, cannery crops, grain, hay and pasture. Native vegetation is Douglas-fir, oak and grass.
DISTRIBUTION AND EXTENT: Woodburn soils occur throughout the Willamette Valley in western Oregon; MLRA 2. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Benton County (Benton Area), Oregon, 1970.
REMARKS: Diagnostic horizons and features include:
Mollic epipedon - the zone from 0 to 17 inches (Ap and A horizons)
Argillic horizon - the zone from 17 to 54 inches (Bt1, Bt2, BCt1, and BCt2 horizons)
Aquultic feature - has redox depletions with chroma of 2 or less within 30 inches of the surface and also aquic conditions for some time in normal years and a base saturation (sum of cations) of 75 percent or less in one or more horizon between the Ap and 30 inches.
Xeric soil moisture regime.
Particle-size control section - the zone from 17 to 37 inches.
ADDITIONAL DATA: Chemical data from Riverside SCS lab or typifying pedon (S62OR-047-004) in Marion County Area, Oregon Soil Survey Manuscript. Other soil survey sample numbers include: S62OR-047-003, S91OR-047-002, S91OR-067-004, S92OR-003-001, S92OR-053-001, S98OR-071-001, S98OR-071-001A,B,C, and D, S98OR-071-006, S98OR-071-006A,B,C, and D.