LOCATION OSWALD CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Aquic Haploxererts
TYPICAL PEDON: Oswald clay - on a nearly level slope of less than one percent slope under irrigated rice at 38 feet elevation. (When described April 3, 1979, the soil was moist throughout. Colors are for dry soil unless otherwise stated.)
Ap--0 to 7 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist, with few distinct mottles yellowish brown and brownish yellow (10YR 5/6, 6/6) and dark yellowish brown and yellowish brown (10YR 4/6, 5/6) moist; moderate medium granular structure; very hard, firm, very sticky and plastic, common very fine and fine roots; few very fine tubular pores and common very fine and fine interstitial pores; neutral (pH 7.0); gradual wavy boundary. (5 to 8 inches thick)
A--7 to 15 inches; grayish brown (10YR 5/2) clay, very dark grayish brown (10YR 3/2) moist, with common fine distinct mottles yellowish brown and brownish yellow (10YR 5/6, 6/6) and dark yellowish brown and yellowish brown (10YR 4/6, 5/6) moist; moderate medium prismatic structure parting to strong medium angular blocky; very hard, firm, very sticky and very plastics few very fine roots; few very fine tubular pores; few fine rounded manganese concretions; many wedge shaped intersecting slickensides at about 20 to 45 degree angles; moderately, alkaline (pH 8.0); gradual wavy boundary. (7 to 14 inches thick)
C--15 to 33 inches; brown (10YR 5/3) clay, dark brown (10YR 3/3) moist, with few fine distinct mottles yellowish brown (10YR 5/6) and dark yellowish brown (10YR 4/6) moist; moderate medium prismatic structure parting to strong medium angular blocky; the lower 4 inches appeared more platy in structure but was not continuous; very hard, firm, very sticky and very plastic; few very fine roots; few very fine tubular pores; few fine rounded manganese concretions; many wedge shaped intersecting slickensides at about 20 to 45 degree angles; slightly effervescent in the lower 4 inches, lime segregated in few soft masses and disseminated; moderately alkaline (pH 8.0); abrupt wavy boundary. (8 to 18 inches thick)
2Cr--33 to 43 inches, light gray (10YR 7/2) siltstone, pale brown (10YR 6/3) moist, with many fine distinct mottles yellowish brown and brownish yellow (10YR 5/4, 5/6, 6/6, 5/8) and dark yellowish brown and yellowish brown (10YR 4/4, 4/6, 5/6) moist, also few fine manganese stains, black (10YR 2/1); massive; very hard, very firm, common very fine and fine tubular and interstitial pores, few thin clay films on fracture faces, strongly effervescent lime segregated in common fine seams; moderately alkaline (pH 8.0).
TYPE LOCATION: Sutter County, California; approximately 2 miles south of the Yuba City limits on Highway 99, then 4.5 miles west on Oswald Road, then 1,700 feet north of the intersection of Boulton Road and Oswald Road, then 60 feet east into field; 2,510 feet west and 1,700 feet north of the southeast corner of section 11, T. 14 N., R. 2 E.
RANGE IN CHARACTERISTICS: Depth to paralithic contact ranges from 20 to 40 inches. The mean annual soil temperature is 60 to 65 degrees F. The difference between the average July and average January soil temperature is 30 to 33 degrees F. Clay content ranges from 35 to 60 percent. Reaction is neutral to moderately alkaline. Common to many intersecting slickensides are at depths of 5 to 40 inches.
The A horizon has dry colors of 10YR 5/2 or 5/3 and moist colors of 10YR 3/2 or 3/3 with few or common mottles of 10YR 5/6, 6/6 or 4/6 moist and dry. It is heavy clay loam, clay or silty clay.
The C horizon has dry colors of 5/3 or 6/3 and moist colors of 4/35 3/3 or 4/2 with few distinct mottles. It is clay or silty clay.
Some pedons have a Cca horizon and a laminar lime capping above the 2Cr horizon.
COMPETING SERIES: These are the Triangle (T) series and the Alo, Altamont, Auld, Ayar, Capay, Centerville, Cibo, Galt (T), Porterville, and Seville soils in other families. Triangle soils are greater than 40 inches deep. The rest lack mottles within 20 inches of the soil surface.
GEOGRAPHIC SETTING: Oswald soils are in basins and on basin rims with slopes of less than 2 percent. They formed in alluvium from mixed sources deposited over unrelated siltstone. Elevations are 20 to 80 feet. Climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation is 16 to 20 inches. Average January temperature is 45 degrees F. and average July temperature is 77 degrees F. The mean annual temperature is about 62 degrees F. The frost-free season is about 270 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Capay soils and the Gridley (T) and Subaco (T) soils. Gridley (T) soils have argillic horizons and are on terraces. Subaco soils are in basins and on basin rims and have dominant chromas moist of less than 1.5.
DRAINAGE AND PERMEABILITY: Poorly drained; very slow runoff; slow permeability. Some areas of this soil are subject to periods of flooding in December through April. A perched water table is at a depth of 18 to 36 inches from December through April.
USE AND VEGETATION: This soil is used for irrigated rice, small grains and row crops.
DISTRIBUTION AND EXTENT: Southeastern part of the Sacramento Valley. Soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Sutter County, California 1979. Series name is from Oswald Road.
OSED scanned by SSQA. Last revised by state on 11/83.