LOCATION COURTNEY OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Abruptic Argiaquolls
TYPICAL PEDON: Courtney gravelly silty clay loam - cultivated. (Colors are for moist soil unless otherwise noted.)
A1--0 to 4 inches; black (10YR 2/1) gravelly silty clay loam, dark gray (10YR 4/1) dry; few fine distinct dark brown (7.5YR 4/4) mottles; strong medium and fine subangular blocky structure; hard, friable, sticky and plastic; many roots; many very fine and fine irregular pores; 20 percent coarse gravel; strongly acid (pH 5.4); clear smooth boundary. (2 to 8 inches thick)
A2--4 to 12 inches; very dark gray (N 3/) gravelly silty clay loam, very dark gray (10YR 3/1) rubbed and dark gray (10YR 4/1) dry; common medium distinct strong brown (7.4YR 4/4) mottles; strong medium and fine subangular blocky structure; hard, friable, sticky and plastic; many roots; many very fine tubular pores; 30 percent gravel; medium acid (pH 5.8); abrupt smooth boundary. (7 to 10 inches thick)
2Bt--12 to 24 inches; dark gray (10YR 4/1) gravelly clay, gray (10YR 5/1) dry; few roots; few very fine pores; few thin clay films and dark coatings on surfaces of peds; 30 percent gravel, few cobbles; slightly acid (pH 6.4); clear smooth boundary. (10 to 20 inches thick)
3C1--24 to 49 inches; dark grayish brown (10YR 4/2) extremely gravelly clay loam, gray (10YR 5/1) dry; massive; very hard, firm,
sticky and plastic; iron stains; 85 percent gravel, few cobbles; slightly acid (pH 6.2).
4C2--49 to 60 inches; dark brown (7.5YR 3/2) mottled, strong brown (7.5YR 5/6) extremely gravelly sand; massive; soft, friable, many very fine and fine pores; 80 percent gravel; neutral (pH 6.7).
TYPE LOCATION: Marion County, Oregon; NW1/4SE1/4 sec. 6, T. 8 S., R. 2 W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 52 to 55 degrees F. The soil has an aquic moisture regime and is saturated with water during the winter. The thickness of the solum ranges from 20 to 36 inches.
The A horizon has hue of 10YR or neutral, value of 2 or 3 moist, 4 or 5 dry, and chroma of 0 through 2 moist and dry. It is silty clay loam or clay loam. It is 15 to 30 percent gravel. This horizon has moderate or strong granular subangular blocky structure. It has few to many distinct or prominent mottles.
The B horizon has hue of 10YR or neutral, value of 3 or 4 moist, 5 or 6 dry, and chroma of 0 through 2. It is gravelly clay or gravelly silty clay with 50 to 60 percent clay, and with an increase in clay of more than 20 percent at the upper boundary. It is 15 to 35 percent rock fragments. This horizon has weak or moderate prismatic or blocky structure. It usually has few to many distinct or prominent mottles but some pedons lack mottles when chroma is 1 or less.
The C horizon is stratified, ranging from clay loam, sandy clay loam, loam to sand with 50 to 85 percent rock fragments, mostly gravel. Contrasting textures are lacking below the argillic horizon within a depth of 40 inches.
COMPETING SERIES: These are the Butler, Clackamas, Conser, Olbut and Waldo series. Butler soils have an A2 horizon, lack rock fragments, and have secondary lime at a depth of 26 to 54 inches. Clackamas soils lack an abrupt textural change and have less than 35 percent clay in the argillic horizon. Conser soils lack an abrupt textural change and have less than 10 percent rock fragments in the solum. Waldo soils lack an argillic horizon. Olbut soils have free carbonates at 10 to 24 inches.
GEOGRAPHIC SETTING: The Courtney soils are in depressions on terraces at elevations of 175 to 800 feet. Slopes are 0 to 3 percent. The soils formed in gravelly fine textured mixed alluvium. The climate is characterized by having dry, cool summers and wet, cool winters. The mean annual precipitation is 40 to 60 inches. The mean annual temperature is 50 to 54 degrees F, the average July temperature is about 67 degrees F, and the average January temperature is about 39 degrees F. The frost-free period is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Salem and the competing Clackamas soils. Salem soils are well drained, moderately fine textured, and have contrasting textures below the argillic horizon and above depths of 40 inches.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow runoff or ponded; very slow permeability.
USE AND VEGETATION: These soils are used for spring grains, grass seed production, hay, and pasture, when drained. The native vegetation is annual and perennial grasses and weeds, wild rose brush, blackberries, and scattered ash trees.
DISTRIBUTION AND EXTENT: Tributary valleys of the Willamette Valley and along the eastern margin of the Willamette Valley, Oregon. These soils are extensive.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Linn County, Oregon, 1924.