LOCATION AWBRIG OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Albaqualfs
TYPICAL PEDON: Awbrig silty clay loam - pasture. (Colors are for moist soil unless otherwise noted.)
Ap1--0 to 2 inches; very dark grayish brown (10YR 3/2) silty clay loam, light brownish gray (10YR 6/2) dry; moderate very fine subangular blocky and fine granular structure; hard, friable, moderately sticky and moderately plastic; many very fine roots; many fine irregular pores; few fine prominent yellowish brown (10YR 5/6) masses of iron accumulation or stains in root channels; strongly acid (pH 5.4); clear smooth boundary. (1 to 6 inches thick)
Ap2--2 to 7 inches; very dark grayish brown (10YR 3/2) silty clay loam, light brownish gray (10YR 6/2) dry; moderate fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine and common fine roots; many very fine tubular and irregular pores; common fine black concretions; common fine faint and distinct dark brown and yellowish brown (10YR 4/3, 4/4) masses of iron accumulation; slightly acid (pH 6.5); abrupt irregular boundary. (4 to 9 inches thick)
2Bsst1--7 to 18 inches; very dark gray (10YR 3/1) clay, gray (10YR 5/1) dry; weak coarse prismatic structure with vertical cracks 1/2 inch or more wide when dry but appearing massive when wet; extremely hard, very firm, very sticky and very plastic; few very fine and fine roots; few very fine tubular pores; few fine yellowish brown and black concretions; common slickensides and pressure faces; slightly acid (pH 6.3); clear wavy boundary. (8 to 27 inches thick)
2Bsst2--18 to 29 inches; very dark grayish brown (10YR 3/2) silty clay, dark grayish brown (10YR 4/2) dry; moderate medium and coarse prismatic structure parting to weak medium and fine subangular blocky; extremely hard, firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; many faint to distinct clay films; many pressure faces; few slickensides; many medium distinct yellowish brown (10YR 5/4) masses of iron accumulation; slightly acid (pH 6.5); gradual boundary. (0 to 17 inches thick)
2BCt--29 to 48 inches; grayish brown (10YR 5/2) silty clay loam, pale brown (10YR 6/3) dry; weak medium prismatic structure; hard, firm, moderately sticky and moderately plastic; many very fine tubular pores; many distinct very dark grayish brown (10YR 3/2) clay films on faces of peds and in pores; many fine prominent yellowish brown (10YR 5/6), brown (7.5YR 4/4) masses of accumulation;, and many fine distinct light gray (10YR 7/2) iron depletions; contains less than 5 percent gravel; neutral (pH 6.6); abrupt smooth boundary. (0 to 22 inches thick)
2C--48 to 60 inches; brown (10YR 4/3) clay loam, pale brown (10YR 6/3) dry;; massive; hard, firm, moderately sticky and moderately plastic; common very fine tubular pores; many distinct dark gray (10YR 4/1) iron depletions; neutral. (pH 7.0)
TYPE LOCATION: Lane County, Oregon; about 2,100 feet west and 40 feet north of the SE corner of section 32, T. 16 S. R. 4 W. Willamette Meridian; Junction City, Oregon, USGS 7.5 minute quad. Latitude 44 degrees, 07 minutes, 41 seconds N.; Longitude 123 degrees, 11 minutes, 44 seconds W. NAD 27.
RANGE IN CHARACTERISTICS: The soil is usually moist and is saturated during the winter and early spring. However, the soil dries out and cracks from the surface to a depth of over 20 inches during the summer nearly every year. The mean annual soil temperature ranges from 52 to 55 degrees F. The solum ranges from 30 to 50 inches thick. The pscs has 50 to 60 percent clay and 0 to 5 percent rock fragments. Depth to the dense clay 2Bt horizon ranges from 5 to 12 inches. The soil has 0 to 5 percent gravel. Depth to aquic conditions with chroma of 2 or less, with or without redox concentrations is 6 to 12 inches.
The A horizon has value of 5 or 6 dry, and chroma of 2 or less moist and dry. In some pedons where the A horizon approaches 12 inches in thickness, there is an intermittent E horizon with value of 4 or 5 moist and 6 or 7 dry. In pedons that have been cultivated for grass seed production and subjected to intensive annual field burning and heavy applications of nitrogen, the Ap horizon may approach these lighter colors. Reaction is slightly acid to strongly acid. It has 27 to 30 percent clay.
The 2Bsst horizon has value of 3 or 4 moist and chroma of 1 or 2 moist and dry. It is very dense and massive when moist, but cracking appears to occur in the same places as indicated by the tonguing between prisms and the wavy boundary or rounded tops to the prisms where not planed off by cultivation. Texture is clay or silty clay and averages 50 to 60 percent clay. Reaction is slightly acid to neutral.
The 2BCt or 2C horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist, 6 dry and chroma of 1 to 4 moist and dry. Texture is clay loam or silty clay loam with 27 to 40 percent clay.
COMPETING SERIES: These are the Adco, Appanoose, Belinda, Chariton, Dayton, Glensted, Putnam, Rubio, and Wagner series. Adco soils lack a discontinuity, have an albic horizon, and have aquic conditions at a depth of 12 to 30 inches. Appanoose and Belinda soils lack a discontinuity and have an albic horizon. Chariton, Putnam, Rubio, and Wagner soils lack a discontinuity and have an albic horizon. Glensted soils have a particle-size control section with 1 to 15 percent chert gravel. Dayton soils are 12 to 24 inches deep to the 2Bt horizon and have an albic horizon.
GEOGRAPHIC SETTING: Awbrig soils are on nearly level to slightly concave or depressed parts of stream terraces at elevations of 180 to 600 feet. Slopes gradients are 0 to 2 percent. The soils formed in stratified silty and clayey mixed alluvium and of lacustrine origin. The climate consists of warm, dry summers and cool, moist winters with an annual precipitation of 40 to 50 inches. The mean annual temperature is 51 to 54 degrees F; the average January temperature is 39 to 40 degrees F; and the average July temperature is about 65 to 67 degrees F. The frost-free period is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bashaw, Clackamas, Coburg, Conser, Courtney, Holcomb, Malabon, and the competing Dayton soils. Bashaw soils do not have an abrupt textural change and on lower flood plains. Clackamas soils are fine-loamy and are on higher terraces. Coburg soils have a mollic epipedon that is 20 to 30 inches thick and has redoximorphic features below 30 inches and is on higher terraces. Conser soils do not have an abrupt textural change and are on similar positions. Courtney soils have a very gravelly or extremely gravelly C horizon with 40 inches and are on similar positions. Holcomb soils have a mollic epipedon and aquic conditions between depths of 12 to 20 inches and are on higher terraces. Malabon soils have a mollic epipedon that is 20 to 30 inches thick and lack redoximorphic features within 40 inches and are on higher terraces.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow runoff or ponded; very slow permeability. Awbrig soils are subject to rare flooding. A perched water table is at its uppermost limit from November toApril and is ponded from December to April. This soil also has an apparent water table.
USE AND VEGETATION: These soils are used for grass seed, hay, pasture, and spring grain crops. Native vegetation is mainly grasses, sedges, rushes, and scattered hawthorn, rose, and Oregon ash.
DISTRIBUTION AND EXTENT: Low stream terraces of the southern Willamette Valley, Oregon; MLRA 2. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lane County Area, Oregon, 1981.
REMARKS: Diagnostic horizons and features include:
Ochric epipedon
Aqualfs feature - the soil has aquic conditions within 12 inches of the soil surface and 50 percent or more redox depletions with or without redox concentrations throughout the argillic horizon.
Albaqualfs feature - have an abrupt textural change between the ochric epipedon and the argillic horizon. The argillic horizon has very slow hydraulic conductivity.
Vertic feature - cracks 1/2 inches wide and presence of slickensides in the upper part of the argillic horizon.
Argillic horizon - the zone from 7 to 48 inches (2Bt1, 2Bt2, and 2BCt horizons)
Particle-size control section - the zone from 7 to 27 inches.
The Awbrig soils are found on the Winkle geomorphic surface in the Willamette Valley, Oregon.
ADDITIONAL DATA: Characterization data for 1 pedon (S65-Oreg-20-1) done by Oregon State University - unpublished and 1 pedon done by the National Soil Survey Lab with soil survey sample number S99OR-043-004.