LOCATION RUSSIAN CAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Cumulic Haploxerolls
TYPICAL PEDON: Russian loam - on a flood plain of 2 percent slope under an irrigated pear orchard with a grass cover crop at 600 feet elevation. (Colors are for dry soil unless otherwise stated. When described on June 2, 1978, the soil was moist throughout.)
Ap-0--8 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak medium and coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; common very fine and few fine and medium tubular pores; neutral (pH 6.8); clear smooth boundary.
A1--8 to 25 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine, medium, and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and coarse and common fine roots; common very fine and few fine and medium tubular pores; silt coatings on peds and in pores; neutral (pH 7.0); clear smooth boundary.
A2--25 to 38 inches; grayish brown (10YR 5/2) loam, very dark grayish brown (10YR 3 2) moist; weak fine, medium, and coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine, fine, medium and coarse roots; common very fine and few fine and medium tubular pores; silt coatings on peds and in pores; neutral (pH 7.0); abrupt smooth boundary. (Combined thickness of the A is 21 to 38 inches)
C--38 to 65 inches; grayish brown (10YR 5/2) very fine sandy loam, very dark grayish brown (10YR 3/2) moist; massive; soft, very friable, nonsticky and slightly plastic; few very fine and coarse, and common fine, and medium roots; common very fine and fine and few medium tubular pores; neutral (pH 7.0).
TYPE LOCATION: Mendocino County, California, 1,000 feet west of the Russian River and 700 feet north of Vichy Springs Road and 1/4 mile west of bridge, 17th tree in the 11th row from avenue north of house, on Alex Thomas's "Home" Pear Ranch, 544,300 feet north and 1,663,400 feet east, Zone 2, California Coordinate system, Ukiah Quadrangle.
RANGE AND CHARACTERISTICS: The soil is more than 60 inches deep. Between a depth of 6 to 18 inches the soil is dry in all parts from June to October where not irrigated and is moist in all parts from December through April. The mean annual soil temperature varies from 59 to 62 degrees F. Mean January soil temperature is 47 degrees F and mean July temperature is 76 degrees F. Organic matter content is 1 to 4 percent to a depth of over 20 inches and decreases irregularly with depth. Base saturation in the upper 30 inches ranges from 75 to 90 percent by sum of cations. The soil reaction is slightly acid to mildly alkaline throughout. The particle-size control section contains 15 to 30 percent fine sand or coarser, 30 to 55 percent silt and 10 to 18 percent clay. The average combined silt, very fine sand and clay are greater than 50 percent.
The A horizon is 10YR 4/2, 5/2 or 5/3. Moist colors are 10YR 3/2 or 3/3. It is loam, silt loam or very fine sandy loam with 12 to 18 percent clay.
The C horizon is 10YR 4/3, 5/2, 5/3 or 6/3. Moist colors are 10YR 3/2, 3/3, 4/2 or 4/3. It is stratified loam, silt loam or very fine sandy loam with 10 to 18 percent clay, 30 to 55 percent silt and 30 to 60 percent sand. In some pedons it is stratified gravelly sandy loam and very gravelly sand at a depth below 30 inches.
COMPETING SERIES: These are the Elder and Nord series. Elder soils are dry from May to November and have less than 50 percent combined clay, silt and very fine sand in the particle-size control section. Nord soils are calcareous below depths of 5 to 10 inches, and are mildly alkaline to very strongly alkaline in the C horizon.
GEOGRAPHIC SETTING: The Russian soils are on flood plains and low stream terraces and have slopes of 0 to 2 percent. The soils formed in alluvium from sedimentary rocks. Elevations are 400 to 1,500 feet. The climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation varies from 32 to 44 inches. Mean January temperature is 44 degrees F; mean July temperature is 72 degrees F; mean annual temperature varies from 54 degrees to 59 degrees F. Frost-free season is 200 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cole, Feliz (T) and Talmage soils. Cole soils are fine. Feliz soils are fine-loamy. Talmage soils are loamy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability in the solum, rapid in gravelly substratum; occasional flooding where not protected.
USE AND VEGETATION: Used for viticulture, orchards and pasture-land. Crops grown are pears, prunes, grapes and irrigated pasture.
DISTRIBUTION AND EXTENT: Northern California in the valleys of the Coast Range. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Mendocino County, California 1980. Soil is named after the Russian River.
ADDITIONAL DATA: NSSL Pedon S78CA-045-110 (type location).