LOCATION RITNER OR

Established Series
Rev. PRS /DRJ/RWL
06/2011

RITNER SERIES

The Ritner series consists of moderately deep, well drained soils formed in clayey colluvium derived from basalt dominantly from the Siletz River Volcanics Formation. Ritner soils occur on broad ridgetops and side slopes of foothills and mountains. Slopes are 2 to 90 percent. The mean annual precipitation is about 50 inches and the mean annual temperature is about 52 degrees F.

TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, mesic Humic Haploxerepts

TYPICAL PEDON: Ritner gravelly silty clay loam, woodland, on a 52 percent southwest-facing slope at an elevation of 1,100 feet. (Colors are for moist soil unless otherwise noted.)

Oi--0 to 1 inch; slightly decomposed litter of needles, leaves, and twigs; abrupt smooth boundary. (0 to 3 inches thick)

A--1 to 6 inches; dark reddish brown (5YR 3/4) gravelly silty clay loam, reddish brown (5YR 4/4) dry; strong fine granular structure; hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine irregular pores; 20 percent fine and medium gravel; moderately acid (pH 5.8); clear smooth boundary. (4 to 9 inches thick)

BA--6 to 16 inches; dark reddish brown (2.5YR 3/4) gravelly silty clay loam, reddish brown (2.5YR 4/4) dry; strong fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many very fine and fine roots; many very fine tubular pores; 30 percent gravel; moderately acid (pH 5.6); clear smooth boundary. (0 to 10 inches thick)

Bw1--16 to 25 inches; dark reddish brown (2.5YR 3/4) very cobbly silty clay, reddish brown (2.5YR 4/4) dry; moderate fine subangular blocky structure; hard, firm, moderately sticky and very plastic; many fine roots; common very fine tubular pores; 25 percent gravel and 15 percent cobbles; strongly acid (pH 5.2); clear smooth boundary. (5 to 16 inches thick)

Bw2--25 to 39 inches; dark reddish brown (2.5YR 3/4) very cobbly silty clay, reddish brown (2.5YR 4/4) dry; moderate medium subangular blocky structure; hard, firm, moderately sticky and very plastic; few very fine roots; few very fine tubular pores; 25 percent cobbles and 30 percent gravel; strongly acid (pH 5.2); abrupt wavy boundary. (0 to 15 inches thick)

2R--39 inches; fractured basalt with few thin tongues of above horizon in fractures; red clay coatings on surface of rock fragments.

TYPE LOCATION: Benton County, Oregon; 5 miles north of Corvallis in Oregon State University's McDonald Forest; located about 1,980 feet north and 2,200 feet east of the southwest corner of section 3, T.11S. R.5W., Willamette Meridian, Airlie South, Oregon USGS 7.5 minute topographic quadrangle (Latitude 44 degrees, 38 minutes, 29 seconds N.; Longitude 123 degrees, 16 minutes, 55 seconds W. NAD 27).

RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 51 to 55 degrees F. The soils are usually moist but are dry between depths of 4 and 12 inches for 45 to 60 consecutive days following the summer solstice within MLRA 2 but ranges to 90 days in MLRA 5. Depth to the fractured bedrock range from 20 to 40 inches. The particle-size control section is 35 to 50 percent clay and has 35 to 75 percent total rock fragments. The amount of rock fragments ranges from 15 to 35 percent in the upper part of the solum to between 35 and 75 percent in the lower part of the Bw horizon, increasing with depth. Rock fragments range in size from gravel to stones. An ochric epipedon that has a moist chroma of 4 is at a depth of less than 10 inches.

The A horizon has hue of 5YR to 10YR, value of 2 or 3 moist, 3 or 4 dry and chroma of 2 to 4 moist and dry. This horizon, in pedons with chroma of 2 or 3 moist is less than 1/3 thickness of the solum. Texture is silty clay loam with 27 to 40 percent clay. It has 10 to 25 percent gravel, 0 to 25 percent cobbles and 0 to 5 percent stones. Reaction is moderately acid.

The BA horizon, when present, has hue of 2.5YR to 7.5YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist and dry. Texture is silty clay loam with 30 to 40 percent clay. It has 10 to 35 percent gravel, 0 to 25 percent cobbles and 0 to 5 percent stones. Reaction is moderately acid.

The Bw horizon has hue of 2.5YR to 7.5YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 4 to 6 moist and dry. Texture is silty clay, clay or heavy silty clay loam with 35 to 50 percent clay. It has 15 to 35 percent gravel, 15 to 45 percent cobbles, and 0 to 20 percent stones. Reaction is strongly acid or moderately acid.

COMPETING SERIES: This is the MacDunn series. MacDunn soils are 40 to 60 inches deep to a paralithic contact.

GEOGRAPHIC SETTING: Ritner soils occur on summit (interfluve component), shoulder (nose slope component), and backslope positions (head slope and side slope components) on broad rolling ridgetops to steep and very steep side slopes of foothills and mountains along the margins of the Willamette Valley in Oregon. Slopes are 2 to 90 percent. Elevation is 240 to 2,200 feet. The soils formed in clayey colluvium derived from basalt. The climate is characterized by warm, wet winters and hot, dry summers. The mean annual precipitation is 40 to 70 inches. The mean annual temperature is 48 to 54 degrees F. The January temperature is 38 to 40 degrees F. and the July temperature is 64 to 67 degrees F. The frost-free period is 160 to 210 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gelderman, Jory, MacDunn, Nekia, Price, Saum, Witzel, and Yamhill soils. Gelderman, Jory, Nekia and Yamhill soils occur on foothills along the margins of the Willamette Valley, Oregon. Gelderman, Jory and Nekia soils have argillic horizons. Price, MacDunn, and Witzel soils occur on steep to very steep side slopes of foothills and mountains. MacDunn soils are fine textured, have more than 35 percent total rock fragments in the particle-size control section and are 40 to 60 inches deep to a paralithic contact. Price soils are fine textured, have less than 35 percent total rock fragments in the particle-size control section, and are greater than 60 inches deep to bedrock. Saum soils are greater than 40 inches to bedrock and are on linear or concave parts of the hillslope. Witzel soils are less than than 20 inches to a lithic contact and have more than 35 percent total rock fragments in the particle-size control section. Yamhill soils have mollic epipedons and are 20 to 40 inches deep to a lithic contact.

DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.

USE AND VEGETATION: These soils are used for timber production, hay and pasture, limited homesite development, wildlife, and watersheds. Native vegetation is Douglas fir, grand fir, ponderosa pine, bigleaf maple, Oregon white oak, western brackenfern, common snowberry, western hazel, Pacific poison oak, baldhip rose, trailing blackberry, evergreen blackberry, western swordfern, American trail plant, fragrant bedstraw, coolwort foamflower, Oregon iris, common whipplea, mountain brome, western fescue, and white hawkweed.

DISTRIBUTION AND EXTENT: Foothills and mountains bordering the margins of the Willamette Valley in Oregon; MLRA 2, 5. The series is of moderate extent.

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

SERIES ESTABLISHED: Benton County (Benton Area), Oregon, 1970.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - from 1 to 16 inches (A, BA horizons)
Humic subgroup - color requirwments are meet from 1 to 39 inches
Cambic horizon - from a depth of 16 to 39 inches (Bw1, Bw2 horizons)
Particle-size control section - from 11 to 39 inches (part of the BA horizon, and all of the Bw1 and Bw2 horizons)

All depths to diagnostic features within the range of characteristics are measured from the top of the first mineral horizon.

Ritner soils occur on the Looney geomorphic surface.

Classification revision 12/02 and 6/2011 from active Typic Dystroxerepts to superactive Humic Haploxerepts based on lab data from associated Price and MacDunn series.

National Cooperative Soil Survey
U.S.A.