LOCATION VALDEZ CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, thermic Aeric Fluvaquents
TYPICAL PEDON: Valdez silt loam - on a less than 1 percent west facing slope at 1 foot elevation in irrigated cropland. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 14 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; few fine brownish yellow (10YR 6/8) mottles, brown (7.5YR 4/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few medium and coarse roots; few very fine tubular and common fine interstitial pores; slightly calcareous, lime segregated in rounded fine soft masses (beet lime was applied); moderately alkaline (pH 8.0); abrupt smooth boundary. (5 to 18 inches thick)
C1--14 to 21 inches; light gray (10YR 7/2) very fine sandy loam, grayish brown (10YR 5/2) moist; many medium brown (7.5YR 4/4) and strong brown (7.5YR 5/6) mottles, dark reddish brown (5YR 3/2) and reddish brown (5YR 4/4) moist; massive (weak tillage pan); slightly hard, very friable, nonsticky and nonplastic; common very fine roots; few very fine and fine tubular pores; common mica flakes; neutral (pH 7.0); abrupt smooth boundary. (6 to 30 inches thick)
C2--21 to 49 inches; pale brown (10YR 6/3) silt loam, brown (10YR 4/3) moist; common fine strong brown (7.5YR 5/6) mottles with pale olive (5Y 6/3) mottling and yellowish red (5YR 4/6) with olive (5Y 4/3) moist mottles in bands, pores, root channels and cleavage planes; strong very thin and medium platy structure with mica visible on cleavage planes; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; slightly alkaline (pH 7.5); clear wavy boundary. (20 to 30 inches thick)
C3--49 to 65 inches; light yellowish brown (10YR 6/4) silt loam, dark yellowish brown (10YR 4/4) moist; common medium strong brown (7.5YR 5/8) mottles, yellowish red (5YR 4/8) moist; strong very thin and medium platy structure with mica visible on cleavage planes; hard, firm, slightly sticky and nonplastic; common very fine roots; common very fine tubular pores; neutral (pH 7.0).
TYPE LOCATION: Yolo County, California; about 1/2 mile SE of railroad siding of Valdez; 4 1/2 miles west and 6 3/4 miles south of Clarksburg; 0.4 mile south of Sutter Road, 0.25 mile east of Sacramento Northern Railroad, 50 feet south of irrigation ditch, T.6 N., R.3 E in an unsectionized area Courtland Quad.
RANGE IN CHARACTERISTICS: Unless drained and not irrigated, the upper 20 inches of the soil usually does not become dry. The mean soil temperature is about 60 degrees to 64 degrees F. The soils have coarse stratification and the organic matter decreases irregularly with increasing depth. The 10 to 40 inch section is dominantly silt loam, silty clay loam, or very fine sandy loam. There is about 18 to 35 percent clay and less than 15 percent material coarser than very fine sand. Except where soil amendments have been used, the soils are noncalcareous or are calcareous only in some pedons below depth of 30 inches. It has distinct or prominent mottles thoughout.
The A horizon is 10YR 6/2, 6/3, 6/4, 7/1, 7/2, 2.5Y 7/2 or 6/2. Moist colors are 10YR 4/4, 4/3, 4/2, 4/1, 3/2, 5/2, 5/3; 2.5Y 4/2 or 3/2. It is strongly acid to moderately alkaline where soil amendments have been applied.
The upper C horizon is 10YR 7/1, 7/2. 6/2; or 5Y 6/2. Moist colors are 10YR 5/1, 5/2, 4/2; 2.5Y 3/2 or 4/2. It ranges from fine sandy loam to silty clay loam. This horizon is slightly alkaline to moderately acid.
The lower C horizon is 10YR 7/1, 7/2, 7/3, 6/2, 6/3, 6/4, 4/1, 3/1; 2.5Y 6/2; 5Y 6/3, 6/4. Moist colors are 10YR, 5/1, 5/2, 5/3, 4/2, 4/3, 4/4, 3/1, 3/2; 5Y 4/3, 4/4 and contains distinct or prominent mottles in some part. It is sandy loam to silty clay loam and is moderately acid to moderately alkaline. Pedons with 2C or 3C horizons are 10YR 3/1 or 4/1. Moist color is 10YR 2/1 or 3/1. Reaction is moderately acid to neutral. They are stratified below a depth of 40 inches with mucky silt loam, mucky silty clay loam, muck and mucky peat.
COMPETING SERIES: These are the Belden and Commerce soils. Belden soils have moderate permeability in the series control section. Commerce soils have a mean annual temperature of about 66 degrees F.
GEOGRAPHIC SETTING: Valdez soils are in river deltas and flood plains near rivers, sloughs and old stream channels at elevations of 15 feet below sea level to 20 feet above. Slopes are 0 to 2 percent. The climate is dry subhumid, with hot dry summers and cool moist winters. Mean annual precipitation is 14 to 19 inches. Average January temperature is 45 degrees F.; average July temperature is 75 degrees F.; mean annual temperature is 60 to 61 degrees F. The average frost-free period is over 260 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Columbia, Lang, Merritt, Sacramento, Sycamore and Tyndall soils. Columbia soils have less than 18 percent clay in the 10 to 40 inch control section. Lang soils are sand or loamy sand in the 10 to 40 inch control section. Merritt soils have mollic epipedons. Sacramento soils have dark A horizons and more than 60 percent clay. Sycamore soils have a dry value of 4 or less in the A horizon. Tyndall soils average less than 18 percent clay in the 10 to 40 inch control section.
DRAINAGE AND PERMEABILITY: Poorly drained under natural conditions; slow to very slow runoff; moderately slow permeability (organic substratum phase has rapid permeability below a depth of 40 inches). The water table fluctuates from 3 feet to below 5 feet in many drained areas.
USE AND VEGETATION: Irrigated areas are used for intensive row and field crops. Alfalfa and orchards are grown where the water table has been lowered. Nonirrigated areas are used for grain and wildlife.
DISTRIBUTION AND EXTENT: The soil occurs along the lower Sacramento River near Suisun Bay and the Sacramento-San Joaquin Delta. The series is of moderate extent in MLRA-16, 17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Yolo County, California, 1971.
REMARKS: The activity class was added to the classification in March of 2003. Competing series were not checked at that time. - ET
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to a depth of 14 inches (Ap)
Aeric subgroup - the zone from 10 to 30 inches has 10YR or 2.5Y hues with chromas of 2 or less in the matrix and distinct or prominent mottles in 5YR or 7.5YR hues.