LOCATION COVE OR+WAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Vertic Endoaquolls
TYPICAL PEDON: Cove silty clay loam, cropland. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 8 inches; very dark gray (10YR 3/1) silty clay loam, dark gray (10YR 4/1) dry; moderate fine subangular blocky structure; hard, firm, sticky and plastic; common fine roots; common very fine and fine pores; many fine distinct yellowish brown and dark reddish brown masses of iron accumulation; moderately acid (pH 5.6); abrupt smooth boundary. (7 to 8 inches thick)
Bg1--8 to 16 inches; very dark gray (10YR 3/1) clay, dark gray (N 4/) dry; weak medium prismatic structure parting to moderate fine subangular blocky; very hard, very firm, very sticky and very plastic; few fine roots; many very fine pores; many fine distinct dark yellowish brown and dark reddish brown masses of iron accumulation; lightly acid (pH 6.1); clear smooth boundary. (7 to 10 inches thick)
Bg2--16 to 41 inches; very dark gray (N 3/) clay, dark gray (N 4/) dry; moderate medium and coarse prismatic structure; very hard, very firm, very sticky and very plastic; few fine roots; common very fine pores; common fine faint dark yellowish brown masses of iron accumulation; few slickensides that do not intersect; few fine fragments of igneous and sedimentary rocks; slightly acid (pH 6.4); clear smooth boundary. (15 to 26 inches thick)
Cg--41 to 60 inches; dark grayish brown (2.5Y 4/2) clay, gray (N 5/) dry; massive; very hard, very firm, very sticky and very plastic; common very fine pores; many fine dark reddish brown and dark yellowish brown masses of iron accumulation; slightly acid (pH 6.4).
TYPE LOCATION: Yamhill County, Oregon; about 50 feet north of the Amity-Bellvue Road and 75 feet west of ditch, NE1/4NW1/4SE1/4 sec. 25, T. 5 S., R. 5 W., Willamette Meridian.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 56 degrees F. The soils are saturated for 4 to 6 months during the winter and spring unless drained, and remain moist below depth of 20 inches nearly continuously but are dry above this depth for 1 to 2 months during the summer. During the summer the soil cracks at some depth above 20 inches, usually at depths between 7 and 20 inches. The solum is 30 to 45 inches thick. It is neutral to moderately acid.
The surface layer generally has 10YR hue but ranges to 2.5Y. The soil has value of 2 or 3 moist, 3 through 5 dry and chroma of 1 or less throughout except that in the A horizon chroma may be as high as 3. It is silty clay loam or clay.
The Bg horizon generally has 2.5Y or neutral hue but ranges to 5Y or 10YR. It has value of 2 through 4 moist, 4 or 5 dry and chroma of 0 to 2 moist and dry. Distinct or prominent redoximorphic concentrations are at depths of less than 20 inches. It is clay or silty clay and averages 50 to 60 percent clay.
The Cg horizon has color and texture similar to the Bg horizon.
COMPETING SERIES: These are the Cosmos, Marna, and Waldorf series. Cosmos soils are 20 to 32 inches to secondary carbonates and have Btg horizons. Marna soils have secondary carbonates at 26 to 48 inches and glacial till at a depth of 24 to 40 inches. Waldorf soils are 26 to 55 inches to secondary carbonates.
GEOGRAPHIC SETTING: The Cove soils are on flood plains and low tream terraces along both large and small streams at elevations of 100 to 2,500 feet. Slopes range from 0 to 3 percent and are plane to slightly concave. The soils formed in deep clayey recent alluvium washed mainly from areas underlain by sedimentary and basic igneous rocks. Winters are cool and moist, and summers are warm and dry. The mean July temperature is 66 degrees F, and the mean January temperature is 37 degrees F. The mean annual temperature is typically 50 to 54 degrees F. but may range to 56 degrees F. in the interior valleys of Curry County, Oregon. The frost-free period is 140 to 210 days. The mean annual precipitation is typically 18 to 60 inches but ranges to 90 inches in the high winter rainfall interior valleys of Curry County, Oregon.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chehalis, Dollar, Hockinson, Labish, McBee, and Wapato soils. Chehalis soils are well drained and are fine-silty. Dollar soils have a fragipan. Hockinson soils have medium texture. Labish soils have a black, organic A horizon and a dark fine-textured and nearly massive B horizon. McBee soils are fine-silty and have chroma of 3 and have mottles below depths of 20 inches. Wapato soils are fine-silty.
DRAINAGE AND PERMEABILITY: Poorly and very poorly drained; slow to ponded runoff; very slow permeability. Common flooding for brief periods occurs from December to April. A high water table fluctuates between 0 and 1.0 foot from the soil surface from December to June.
USE AND VEGETATION: Most of these soils are cultivated. Most of the soil is in hay and pasture, and some spring grain is grown. Native vegetation is sedges, grasses and a few ash, willows, and other trees.
DISTRIBUTION AND EXTENT: Willamette Valley, Roque Valley, and other interior valleys of southern and southwestern Oregon and in southwestern Washington; MLRA 2, 5. The soil is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yamhill County, Oregon, 1917.
REMARKS: This draft reflects a change in classification from Vertic Haplaquolls to Vertic Epiaquolls based on revision of Soil Taxonomy.
Diagnostic horizons and features recognized:
Mollic epipedon - from 0 to 16 inches (Ap and Bg1 horizons).
Vertic feature - presence of cracks and slickensides within 125 cm of surface.
Aquic feature - chroma of 2 or less and distinct redox concentrations from 0 to 60 inches.