LOCATION AMITY OREstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Argiaquic Xeric Argialbolls
TYPICAL PEDON: Amity silt loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; many irregular pores; moderately acid (pH 5.8); clear smooth boundary. (5 to 8 inches thick)
A--7 to 16 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many roots; common irregular pores and few very fine tubular pores; moderately acid (pH 5.8); clear smooth boundary. (5 to 10 inches thick)
E--16 to 22 inches; dark gray (10YR 4/1) silt loam, light gray (5Y 7/1) dry;; weak medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common roots; many irregular pores; common medium brown and black concretions; common fine faint brown and black masses of iron accumulation; moderately acid (pH 5.8); clear wavy boundary. (4 to 12 inches thick)
2Bt1--22 to 28 inches; grayish brown (10YR 5/2) silty clay loam, pale brown (10YR 6/3); weak medium prismatic structure that parts to moderate very coarse subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few roots; common very fine tubular pores; clear silt and sand grains on faces of prisms; common distinct clay films along pores and on faces of peds; common fine faint brown and black masses of iron accumulation; moderately acid (pH 6.0); gradual wavy boundary. (4 to 13 inches thick)
2Bt2--28 to 35 inches; light olive brown (2.5Y 5/4) silty clay loam, very pale brown (10YR 7/4) dry; weak coarse prismatic structure that parts to moderate coarse subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; few fine roots; common very fine tubular pores; common distinct clay films along pores and on faces of peds; common fine distinct reddish brown, gray and black masses or iron accumulation and depletions; slightly acid (pH 6.2); diffuse wavy boundary. (4 to 14 inches thick)
2C--35 to 72 inches; olive brown (2.5Y 4/4) silt loam, very pale brown (10YR 7/4) dry; massive; hard, friable, slightly sticky and slightly plastic; common very fine tubular pores; common fine faint masses of iron accumulation; slightly acid (pH 6.4).
TYPE LOCATION: Linn County, Oregon; 5,000 feet east from Grand Prairie School, 50 feet west of north and south gravel road, located about 200 feet north and 2,600 feet east of SW1/4, section 15, T. 11 S., R. 3 W. Willamette Meridian; Tangent USGS 7.5 minute topographic quadrangle; Latitude 44 degrees, 36
minutes, 26 seconds N.; Longitude 123 degrees, 02 minutes, 15 seconds W. NAD 27.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry in all parts between a depth of 4 and 12 inches for 45 to 60 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 18 inches thick. Depth to aquic conditions with chroma of 2 or less is 10 to 18 inches.
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 or subangular blocky structure. Texture is silt loam with 15 to 25 percent clay. Reaction is strongly acid or moderately acid.
The E horizon has value of 3 to 5 moist, 6 or 7 dry and chroma of 0 to 2 moist and dry. Texture is silty clay loam with 20 to 30 percent clay. Reaction is strongly acid to slightly acid. It has few to common, faint to distinct redox concentrations.
The 2Bt horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist, 6 or 7 dry and chroma of 2 to 4 moist and dry. It has weak to moderate prismatic or subangular structure. In the lower part it has some brittleness like that of fragipans. Texture is silty clay loam with 27 to 35 percent clay and less than 15 percent sand coarser than very fine sand. Reaction is moderately acid to neutral. It has few to common, faint to distinct redox concentrations.
The 2C horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist, 6 or 7 dry and chroma of 2 to 4 moist and dry. Texture is silt loam or silty clay loam with 15 to 30 percent clay. Reaction is moderately acid to neutral. It has few to common, faint to distinct redox concentrations.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Amity soils are on broad terraces at elevations of 150 to 400 feet. Slopes range from 0 to 3 percent. The soils formed in indistinctly stratified silty alluvium and lacustrine silts of upper Pleistocene age. Beginning at the surface of the mineral soil, the depositional stratigraphy of the Amity soil profile developed in the following Willamette Formation Members: (1) Greenback Member, and (2) Irish Bend Member. Summers are warm and dry and winters are cool and moist. The average annual precipitation is 40 to 50 inches. The average January temperature is 39 to 40 degrees F. and average July temperature is 65 to 67 degrees F. The average annual temperature is 50 to 54 degrees F. The frost-free season is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Aloha,
Concord,
Dayton,
Willamette, and
Woodburn series. Concord and Dayton soils have aquic conditions and 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
horizon. They occur in depressions on terraces. Willamette soils lack aquic conditions with chroma of 2 or less between 0 and 40 inches and do not have an albic horizon. They are on higher terraces or more sloping positions. Aloha soils do not have a mollic epipedon or an albic horizon and are on higher terraces. Woodburn soils have aquic conditions with chroma of 2 or l3ss and redox concentrations at a depth of 20 to 30 inches, lack an albic horizon, and are on higher terraces or more sloping positions.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderately slow permeability. An apparent water table is at its uppermost limit from December toApril.
USE AND VEGETATION: Most of the soil is cropland or in pasture. Small grain, grass seed, and hay are the main crops. Some cannery crops are grown where the soil is artificially drained. A small amount remains in native vegetation of annual and perennial grasses, wild blackberries, wild rose, and widely spaced oak trees.
DISTRIBUTION AND EXTENT: Amity soils are located throughout the Willamette Valley of western Oregon; MLRA 2. They are extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yamhill County, 1917.
REMARKS: Diagnostic horizons and features include:
Mollic epipedon - the zone from 0 to 16 inches (Ap and A horizons)
Albic horizon - the zone from 16 to 22 inches (E horizon)
Argillic horizon - the zone from 22 to 35 inches (2Bt1 and 2Bt2 horizons)
Argiaquic feature - Does not have an abrupt textural change from the albic to argillic horizon and has a xeric moisture regime.
Argialboll- Has an albic horizon that has chroma of 2 or less and has redox concentrations in the albic or argillic horizon above a depth of 40 inches.
ADDITIONAL DATA: Characterization data for 2 profiles (S59OR-043-004 and S59OR-043-005) in Riverside Soil Survey Laboratory Report for soils from the Willamette Valley by SCS Soil Survey Laboratory, Riverside California, 1959. In addition, characterization data is available for S92OR-053-003 and S92OR-003-003, NSSL, Lincoln, NE.