LOCATION ALOHA OREstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Haploxerepts
TYPICAL PEDON: Aloha silt loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 8 inches; dark brown (10YR 3/3) silt loam, pale brown (10YR 6/3) dry; moderate fine subangular blocky structure; friable, slightly hard; nonsticky and slightly plastic; common roots; common irregular pores; common fine shot; moderately acid (pH 6.0); abrupt smooth boundary. (6 to 9 inches thick)
BA--8 to 15 inches; brown (10YR 4/3) silt loam, light yellowish brown (10YR 6/4) dry; common medium faint dark grayish brown, dark brown, and brown (10YR 4/2, 10YR 5/3, 7.5YR 3/2) redox concentrations as masses and depletions; moderate fine subangular blocky structure; friable, slightly sticky and slightly plastic; common roots; many very fine tubular pores; moderately acid (pH 5.8); clear smooth boundary. (0 to 9 inches thick)
Bt--15 to 22 inches; dark yellowish brown (10YR 4/4) silt loam, pale brown (10YR 6/3) dry; common fine faint dark grayish brown, brown, and dark brown (10YR 4/2, 10YR 5/3, 7.5YR 3/2) redox concentrations as masses and depletions; moderate fine subangular blocky structure; firm, hard, slightly sticky and slightly plastic; common roots; many medium fine and very fine tubular pores; few faint clay films in pores, few black coatings on peds; few medium shot; moderately acid (pH 5.8); clear wavy boundary. (5 to 9 inches thick)
Bw1--22 to 31 inches; dark yellowish brown (10YR 4/4) silt loam, pale brown (10YR 6/3) dry; many medium distinct redox concentrations as masses and depletions of dark brown, dark gray, and brown (7.5YR 4/2, 10YR 4/1, 10YR 3/4) moist; weak medium subangular blocky structure parting to moderate fine subangular blocky; firm, hard, slightly sticky and slightly plastic; slightly brittle; few roots; many very fine and few fine tubular pores; common black coatings; vertical surfaces of peds and all pores have a few faint darker colored coatings or cutans; common fine shot; moderately acid (pH 5.8); gradual wavy boundary. (6 to 13 inches thick)
Bw2--31 to 46 inches; variegated brown and dark brown (10YR 5/3 and 4/3) silt loam, pale brown (10YR 6/3) dry; many medium and fine faint and distinct depletions and redox concentrations as masses of dark grayish brown and reddish brown (10YR 4/2, 5YR 4/4) moist; weak coarse subangular blocky structure; firm, slightly sticky and slightly plastic; brittle; few roots; many very fine and few fine pores; common medium black coatings; common fine shot; common micaceous fragments; few thin coatings or cutans on vertical surfaces of peds; over 60 percent of the horizon exhibits gray clean sand and silt particles in a patchy pattern along surfaces of peds and in the larger pores; moderately acid (pH 5.8); gradual wavy boundary. (0 to 18 inches thick)
Bw3--46 to 60 inches; dark yellowish brown (10YR 3/4) silt loam, pale brown (10YR 6/3) and yellowish brown (10YR 5/4) dry; common coarse dark grayish brown (10YR 4/2) depletions and streaks; few black coatings; massive; firm, slightly sticky and slightly plastic; brittle; few coarse pores and many fine and very fine pores; micaceous; moderately acid (pH 6.0); gradual irregular boundary. (12 to 16 inches thick)
C--60 to 65 inches; dark yellowish brown (10YR 4/4) very fine sandy loam, light yellowish brown (10YR 6/4) dry; massive friable, with common firm nodules, nonsticky and nonplastic; many very fine pores.
TYPE LOCATION: Washington County, Oregon; about 200 feet south of 40 feet east of the end of the country road; NW1/4 SW1/4 NW1/4 section 16, T.1S., R.2W Willamette Meridian. (Latitude 45 degrees, 28 minutes, 50 seconds N., Longitude 122 degrees, 56 minutes, 52 seconds W. NAD 27). Scholls Oregon USGS topographic quadrangle.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 54 degrees to 56 degrees F. The soils are usually moist but are dry for 45 to 60 consecutive days in all parts between depths of 4 and 12 inches following the summer solstice. The soils are more than 60 inches deep. Depth to aquic conditions with chroma of 2 or less with or without redox concentrations is 8 to 20 inches. Depth to the brittle layers is 20 to 40 inches. The soils commonly have an ochric epipedon but some pedons have a mollic epipedon less than 10 inches thick.
The A horizon has hue of 10YR or 7.5YR, value of 3 moist, 5 or 6 dry, and chroma of 2 or 3 moist and dry. It is loam or silt loam with 15 to 20 percent clay. Reaction is moderately acid.
The BA horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 3 or 4 moist and dry. It is silt loam or loam with 15 to 25 percent clay. Reaction is slightly acid to moderately acid.
The Bw or Bt horizons have value of 4 or 5 moist, 6 dry, and chroma of 3 or 4 moist and dry above depth of 20 inches and 2 through 4 below a depth of 20 inches. Redox concentrations are faint to distinct throughout. It is silt loam or loam with 18 to 27 percent clay and less than 15 percent coarser than very fine sand. The Bw horizon ranges from slightly brittle to a very weak fragipan, and has few to continuous coatings of clean, gray sand and silt grains. Clay or organic coatings range from few faint to faint continuous, but are not accompanied by any appreciable increase in clay content over the A and Bt horizon. Reaction is slightly acid to moderately acid.
The C horizon is silt loam, loam or very fine sandy loam.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: The Aloha soils are on broad valley terraces at elevations of 150 to 350 feet. Slopes range from 0 to 8 percent. The soils formed in mixed alluvium or lacustrine silts. The climate is characterized by warm, wet winters and hot, dry summers. Average July temperature is 66 degrees F., average January temperature is 37 degrees F., average annual temperature is 52 degrees to 54 degrees F. Average annual rainfall is 40 to 60 inches. The frost-free season is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Amity, Dayton, Helvetia, Huberly, Quatama, Willamette, Wollent, and Woodburn soils. Dayton, Huberly, and Wollent soils are on concave positions on terraces. Helvetia soils are on older high terraces and footslopes. Quatama soils are on lower terraces. Amity, Willamette, and Woodburn soils are on slightly higher terraces. Amity soils have a Bt horizon and a mollic epipedon. Dayton soils have a light colored A horizon, a clayey Bt horizon and are poorly drained. Helvetia soils are moderately well drained soils with a silty clay argillic horizon. Huberly soils have a fragipan and are poorly drained. Quatama soils are moderately well drained and have a clay loam argillic horizon. Willamette and Woodburn soils have a mollic epipedon and an argillic horizon. Wollent soils are poorly drained and have an umbric epipedon 10 inches or more thick.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderately slow permeability. A perched water table is at a depth of 1.0 to 2.0 feet from the soil surface from December through April.
USE AND VEGETATION: Most of these soils are cultivated. Orchards, berries, grain, hay and pasture are major crops. Native vegetation mainly Douglas-fir, Oregon white oak, Oregon grape, hazelbrush, alder, grasses and forbs.
DISTRIBUTION AND EXTENT: Along the southern part of the Tualatin Valley and northern part of the Willamette Valley in northwestern Oregon. MLRA 2. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Washington County, Oregon, l974
REMARKS: Diagnostic horizons and other features:
Ochric epipedon - the zone from 0 to 8 inches (Ap horizon)
Cambic horizon - the zone from 15 to 60 inches (Bt, Bw1, Bw2, and Bw3 horizons)
Aquic 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.
Fragic soil properties - the zone from 22 to 60 inches. (Bw1, Bw2, and Bw3 horizons)
ADDITIONAL DATA: Characterization data from 3 representative pedons with User Pedon ID # 91OR-067-005, 91OR-067-006, and 04OR-047-001.