LOCATION PARRETT                 OR

Tentative Series
IRD. DRJ/RWL
06/2011

PARRETT SERIES

The Parrett series consists of moderately deep, well drained soils that formed in basalt colluvium. The Parrett soils are on summits and convex side slopes in areas affected by mass movement. Slopes range from 2 to 90 percent. The mean annual temperature is about 52 degrees F., and the mean annual precipitation is about 45 inches.

TAXONOMIC CLASS: Fine, mixed, active, mesic Typic Humixerepts

TYPICAL PEDON: Parrett silty clay loam, in an area of Saum-Parrett complex, 2 to 12 percent slopes at an elevation of 810 feet. (Colors are for dry soil unless otherwise noted)

A--0 to 7 inches; brown (7.5YR 4/4), broken face and brown (7.5YR 4/4) crushed silty clay loam, dark brown (7.5YR 3/2) broken face and dark brown (7.5YR 3/3) crushed, moist; strong medium granular structure parting to strong fine granular; very friable, slightly hard, moderately sticky, moderately plastic; common fine and medium roots and many very fine roots; many very fine, fine, and medium tubular pores; 3 percent fine spherical moderately cemented iron-manganese concretions; 2 percent subrounded basalt gravel; very strongly acid (pH 4.7); clear smooth boundary. (5 to 12 inches thick)

BA--7 to 17 inches; brown (7.5YR 4/4), broken face and brown (7.5YR 4/4) crushed silty clay loam, dark brown (7.5YR 3/3) broken face and dark brown (7.5YR 3/3) crushed, moist; moderate medium subangular blocky structure; friable, hard, moderately sticky, moderately plastic; few fine roots, common medium roots, and many very fine roots; common fine and medium and many very fine tubular pores; 5 percent fine spherical moderately cemented iron-manganese concretions; 2 percent subrounded basalt gravel; strongly acid (pH 5.2); gradual wavy boundary. (5 to 11 inches thick)

Bt--17 to 27 inches; brown (7.5YR 4/4) broken face and strong brown (7.5YR 4/6) crushed silty clay loam, dark brown (7.5YR 3/3) broken face and brown (7.5YR 4/3) crushed, moist; moderate medium subangular blocky structure; friable, hard, moderately sticky, moderately plastic; few fine roots and common very fine and medium roots; few fine and common very fine and medium tubular pores; 5 percent distinct clay films on all faces of peds and 15 percent faint clay films on surfaces along pores; 5 percent fine spherical moderately cemented iron-manganese concretions; 5 percent subrounded basalt gravel and 10 percent subrounded moderately cemented basalt paragravel; moderately acid (pH 5.7); abrupt wavy boundary. (8 to 20 inches thick)

Cr--27 to 37 inches; moderately cemented basalt.

TYPE LOCATION: Yamhill County, Oregon; about 2,300 feet east and 2,900 feet south of the northwest corner of section 3, T. 6 S., R. 4 W. Willamette Meridian. (Latitude 45 degrees, 4 minutes, 42.9 seconds N., Longitude 123 degrees, 9 minutes, 48.1 seconds W. NAD 83). Amity, Oregon USGA topographic quadrangle.

RANGE IN CHARACTERISTICS: The mean annual soil temperature is 53 to 55 degrees F. The soils are usually moist but are dry for 45 to 75 consecutive days in all parts between depths of 4 and 12 inches following the summer solstice. Depth to basalt is 20 to 40 inches. The particle-size control section averages 35 to 50 percent clay. The B horizon has a base saturation (NH4OAc) of 60 to 70 percent. The umbric epipedon is 10 to 20 inches thick.

The A horizon has hue of 7.5YR, value of 3 moist and 4 or 5 dry, and chroma of 2 or 3 moist and 3 or 4 dry. Texture is silty clay loam or silt loam with 24 to 35 percent clay. It has 1 to 5 percent gravel. It has 1 to 5 percent Fe/Mn concretions. Reaction ranges from very strongly acid to slightly acid.


The AB or BA horizons have hue of 7.5YR, value of 3 or 4 moist, 4 or 5 dry, chroma of 3 or 4 moist, and 4 to 6 dry. Texture is silty clay loam, clay, or silty clay with 30 to 45 percent clay. It has 1 to 15 percent gravel and 0 to 5 percent cobbles. It has 1 to 5 percent Fe/Mn concretions. Reaction ranges from strongly acid to slightly acid.


The Bt or Bw horizons have hue of 7.5YR or 5YR, value of 3 or 4 moist, 4 or 5 dry, chroma of 3 to 6 moist and 4 to 6 dry. Texture is silty clay loam, clay, or silty clay with 35 to 50 percent clay. It has 5 to 35 percent paragravel, 0 to 15 percent paracobbles, 1 to 20 percent gravel, and 0 to 10 percent cobbles. It has 1 to 5 percent Fe/Mn concretions. Reaction ranges from moderately acid to slightly acid.

The Cr horizon is weakly to moderately cemented becoming more strongly cemented with depth.

COMPETING SERIES: This is the Saum series. Saum soils are greater than 40 inches to basalt bedrock.

GEOGRAPHIC SETTING: The Parrett soils are on summits and convex side slopes in areas that have been affected by mass movement. Slopes are 2 to 90 percent. The soils occur at elevations of 250 to 1,600 feet. The soils formed in colluvium from various members of the Columbia River Basalt Group. The climate is characterized by warm, wet winters and hot, dry summers. The mean annual precipitation is 40 to 50 inches. The mean annual temperature is 50 to 54 degrees F., mean January temperature is 39 to 40 degrees F., and mean July temperature is 65 to 67 degrees F. The frost-free period is 165 to 210 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cottrell, Ritner, Witzel, and the competing Saum soils. Cottrell soils have redoximorphic depletions with value of 4 or more and chroma of 2 or less within depths of 10 to 30 inches. They occur on concave positions with slopes of less than 12 percent. Ritner soils are clayey-skeletal. Witzel soils are less than 20 inches to a lithic contact. These soils are on convex positions. Saum soils are on linear or concave positions.

DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.

USE AND VEGETATION: These soils are used mainly for home sites, orchards, pasture, forestland, vineyards, Christmas trees, wildlife habitat, and recreation. Vegetation includes an overstory of Douglas-fir, grand fir, Oregon white oak with an understory of western sword fern, Pacific poison oak, California hazelnut, common snowberry, and yerba buena.

DISTRIBUTION AND EXTENT: Foothills of the Willamette Valley, Oregon. MLRA 2. The series is inextensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon.

SERIES PROPOSED: Yamhill County, Oregon 2006. The name is from Parrett Mountain in Yamhill, Clackamas, and Washington Counties, Oregon.

REMARKS: The diagnostic horizons and features recognized in this pedon include:
Umbric epipedon - from a depth of 0 to 17 inches (A and BA horizons).
Cambic horizon - from a depth of 17 to 27 inches (Bt horizon).
Paralithic contact - from a depth of 27 to 37 inches (Cr horizon).
Particle-size control section - from a depth of 10 to 27 inches (BA and Bt horizon) with a weighted average of greater than 35% clay and no increase in clay by 1.2% from the horizon above.

ADDITIONAL DATA: Characterization data from 1 representative pedon with User Pedon ID # 03OR-071-010.

---

National Cooperative Soil Survey
U.S.A.