LOCATION EGBERT CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Cumulic Endoaquolls
TYPICAL PEDON: Egbert silty clay loam - on a West facing slope of less than 1 percent under cropland at 3 feet below sea level. (Colors are for dry soil unless otherwise stated.)
Ap--0 to 6 inches; gray (10YR 5/1) silty clay loam, very dark gray (10YR 3/1) moist; few fine distinct yellowish brown (10YR 3/4) mottles, very dark gray (10YR 3/1) moist; moderate medium and coarse granular structure; very hard, firm, sticky and plastic; many very fine and fine roots; common very fine tubular and interstitial pores; slightly acid (pH 6.5); clear smooth boundary. (5 to 10 inches thick)
A--6 to 31 inches; gray (10YR 5/1) silty clay loam, very dark gray (10YR 3/1) moist; strong very coarse prismatic structure; very hard, firm, sticky and plastic; many very fine roots; common very fine and fine tubular pores, neutral (pH 7.0); gradual wavy boundary. (19 to 25 inches thick)
Cg1--31 to 45 inches; gray (10YR 6/1) silty clay loam, very dark gray (10YR 3/1) moist; common fine prominent mottles of brown (7.5YR 4/4) and dark grayish brown (2.5Y 4/2) moist; moderate very coarse prismatic structure; very hard, very firm sticky and plastic; many very fine roots; many very fine, fine and few medium tubular pores; slightly acid (pH 6.5); diffuse smooth boundary. (10 to 15 inches thick)
Cg2--45 to 60 inches; gray (5Y 6/1) silty clay loam, dark gray (5Y 4/1) moist; many large prominent mottles of dark brown (7.5YR 4/4) moist; moderate very coarse prismatic structure; very hard, firm, sticky and plastic; many very fine roots; common very fine and fine tubular pores; slightly acid (pH 6.2).
TYPE LOCATION: Solano County, California. 0.7 miles west and 2.2 miles north of the west end of the Ryer Island Ferry (ferry located two miles northeast of Rio Vista, California) in the Yolo Bypass of an unsectionized area. Rio Vista Quadrangle.
RANGE IN CHARACTERISTICS: The soils are usually moist throughout unless drained and not irrigated. Drained areas have moist chromas of 1 immediately below the mollic epipedon. The mean annual soil temperature is 61 to 65 degrees F. The 10 to 40 inch control section has 35 to 50 percent clay. Organic matter content averages 2 to 10 percent. Stratas 1/4 to 2 inches thick may be present that have 10 to 50 percent organic matter. Some pedons have thin layers with concentrations of red concretions giving a gravelly or gritty feel. These layers with concretions have low bulk density.
The A horizon is 10YR 5/1, 5/2, 5/3, 4/2, 4/1, 3/1 and has distinct or prominent mottles. Moist colors are 10YR 3/3, 3/2, 3/1, 2/1 or N 3/0, 2/0. It has moderate or strong granular or subangular blocky structure. It is mucky clay loam, clay loam, silty clay loam, silty clay, or clay. Organic matter content is 1 to 25 percent. It is slightly alkaline to slightly acid, but may become more acid when dry. It is more than 24 inches thick.
The lower part of the A horizon, the upper part of the the C horizon and Ab horizon where present is 10YR 7/1, 6/1, 5/1, 4/1, 5/2, 4/2; 5Y 5/1, 4/2, 4/1, 2/1 N 2/0. Moist colors are 10YR 3/1, 3/2, 2/2; 5Y 3/1, 2/1. Distinct or prominent mottles are present. It is clay loam, silty clay loam, silty clay or clay. It is slightly alkaline to slightly acid but may become more acid when dry.
The Cg horizon is 10YR 6/1; 5Y 7/1, 6/1, 5/1, 5/2, 5/3, 4/2, 4/3; 2.5Y 6/2, 5/2, 4/2; 5GY 6/1, 5/1 5G 5/1; 5BG 5/1. Moist colors are 10YR 5/1, 4/1, 3/1; 5Y 5/1, 4/1, 4/2, 3/2; 2.5Y 4/2, 5/2; 5GY 5/1, 4/1. Distinct or prominent mottles are present. It is sandy clay loam, clay loam, silty clay loam, or clay. Strata of sand, loamy fine sand or loamy coarse sand may be present below 40 inches. It is slightly acid to slightly alkaline but may be moderately alkaline and/or calcareous below 40 inches.
COMPETING SERIES: These are the Gazwell (T), Girard, Godwin and Peltier (T). Gazwell soils have a buried Histosol within 40 inches. Girard soils have a lithic contact between 20 to 40 inches. Godwin soils have moderately slow permeability and are somewhat poorly drained. Peltier soils have weighted average of 10 to 25 percent organic matter in the 10 to 40 inch zone.
GEOGRAPHIC SETTING: The Egbert soils are on nearly level to gently sloping flood plains, in backswamps or basins of river deltas. Slopes are 0 to 5 percent. The soils formed in alluvium weathered from mixed sources. Elevations are 15 feet above to 10 feet below sea level. The climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation varies from 10 to 18 inches. Mean January temperature is 47 degrees F; mean July temperature is 76 degrees F; mean annual temperature ranges from 59 to 62 degrees F. The frost-free season ranges from 250 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Peltier and Ryde soils and the Dierssen, Gazwell, Merritt, Sacramento, Scribner and Valpac soils. Dierssen soils have a hardpan between 20 to 40 inches. Gazwell soils have an organic layer between 28 and 39 inches. Merritt soils lack mottles in the mollic epipedon. Sacramento soils have cracks in the upper part and have a very fine textural control section. Scribner and Valpac soils have fine-loamy 10 to 40 inch control sections.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow or slow runoff; slow permeability (sandy substratum phase has rapid permeability below a depth of 40 inches). Levees and drains are required to control both surface and subsurface water. Drained areas have a water table within 3 to 6 feet during the growing season.
USE AND VEGETATION: Used for irrigated cropland. The principal crops are sugar beets, tomatoes, safflower, alfalfa, barley, corn and milo. Principal native plants are annual grasses, forbs and several members of the rush and sedge families.
DISTRIBUTION AND EXTENT: Mainly in the lower end of the Sacramento Valley. The series is of small extent in MLRA-14, 16, 17.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Solano County, California, Suisun Area, 1930.
REMARKS: Egbert soils as mapped in the 1977 Contra Costa Co. SSA are now excluded from this revised concept. The pH values in typical pedon were described when the soil was moist.
The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET
Diagnostic horizons and other features recognized in this pedon are:
Mollic epipedon - the zone from the surface to a depth of 31 inches (Ap, A)
Mineralogy is assumed to be mixed.
Cumulic subgroup - the mollic epipedon is greater than 24 inches thick and the organic carbon decreases irregularly with increasing depth.