LOCATION CHULOAK CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Typic Argixerolls
TYPICAL PEDON: Chuloak coarse sandy loam on a less than 1 percent slope at an elevation of 85 feet in an orchard. (When described March 8, l979, the soil was moist throughout. Colors are for dry soil unless otherwise stated).
Ap--0 to 11 inches; grayish brown (10YR 5/2) coarse sandy loam, very dark gray (10YR 3/1) moist; weak medium subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; common very fine interstitial and tubular pores; moderately acid (pH 5.8); clear smooth boundary. (6 to 12 inches thick)
A--11 to 19 inches; grayish brown (10YR 5/2) coarse sandy loam, very dark grayish brown (10YR 3/2) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine interstitial and tubular pores; slightly acid (pH 6.1); clear wavy boundary. (6 to 10 inches thick)
Bt--19 to 44 inches; brown (10YR 5/3) sandy clay loam, brown (10YR 4/3) moist; moderate coarse subangular blocky structure; very hard, firm, sticky and plastic; few very fine and fine roots; few very fine interstitial pores; few thin clay films on faces of peds and bridging sand grains; slightly acid (pH 6.2); clear wavy boundary. (20 to 28 inches thick)
C1--44 to 55 inches; pale brown (10YR 6/3) fine sandy loam, brown (10YR 4/3) moist; common medium distinct brown (7.5YR 5/4) mottles, brown (7.5YR 4/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; many very fine interstitial pores; neutral (pH 6.6); clear wavy boundary. (8 to 12 inches thick)
C2--55 to 64 inches; pale brown (10YR 6/3) loamy coarse sand, brown (10YR 5/3) moist; common medium distinct brown (7.5YR 5/4) mottles, brown (7.5YR 4/4) moist; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine roots; many very fine interstitial pores; neutral (pH 6.9).
TYPE LOCATION: San Joaquin County, California; about 3.5 miles southwest of Escalon; 2450 feet north and 500 feet west of the SE corner of section 14, T.2 S., R.8 E. MDBM. Avena Quadrangle.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 62 to 65 degrees F. The difference between mean summer and mean winter soil temperatures is greater than 30 degrees F. The soil moisture control section, 6 to 20 inches, is dry in all parts from June 1 to September 30, unless irrigated, and is moist in some or all parts from November 1 to May 31. Distinct or prominent mottles are present in the lower B or C horizons. Up to 15 percent pebbles may occur in any horizon. Coarse and very coarse sand particles make up 25 to 40 percent of the A and B horizons.
The A horizon has color of 10YR 5/2, 5/1, 4/2, or 4/1. Moist color is 10YR 3/2 or 3/1. It is moderately acid or slightly acid. Some pedons are neutral or mildly alkaline as a result of soil amendments. Organic matter is 1 to 2 percent to a depth of 10 inches and is less than 1 percent at 20 inches.
The Bt horizon has color of 10YR 5/3, 4/2, 5/2 or 7.5YR4/2. Moist color is 10YR 4/3 or 4/2. It is slightly acid or neutral. It is sandy loam, loam or sandy clay loam with 18 to 25 percent clay.
The C horizon has color of 10YR 6/3 or 5/3. Moist color is 10YR 5/3 or 4/3. It is fine sandy loam, sandy loam or loamy coarse sand.
COMPETING SERIES: These are the Bohna, Chualar, Franciscan, Feethill, Pinto, Shimmon, Soper and Tajea soils. Bohna soils have a paralithic contact at depths greater than 40 inches. Chualar soils have soil temperatures with differences between mean summer and mean winter of less than 19 degrees F. Franciscan, Shimmon, Tajea, Feethill, and Soper have bedrock at depths of 20 to 40 inches. Pinto soils have an abrupt boundary between the A horizon and the Bt horizon and have soil temperatures with differences between mean summer and mean winter of less than 19 degrees F.
GEOGRAPHIC SETTING: The Chuloak soils are on low alluvial fans at elevations of 70 to 100 feet. Slopes are 0 to 2 percent. They formed in alluvium derived mainly from granitic rock sources. Climate is subhumid with hot dry summers and cool moist foggy winters. Mean annual precipitation is 11 to 12 inches. Mean annual temperature is 60 to 63 degrees F. Average January temperature is 45 degrees F. Average July temperature is 77 degrees F. The frost-free period is 250 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Columbia, Delhi, Honcut, Manteca, Tinnin and Veritas soils. Columbia soils are on flood plains. Delhi, Honcut, Manteca, Tinnin and Veritas have the same topographic position. Columbia, Honcut and Veritas soils are coarse-loamy and lack argillic horizons. Delhi and Tinnin soils are sandy and lack argillic horizons. Manteca soils have duripans at depths of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow runoff; moderately slow permeability.
USE AND VEGETATION: Used mainly for irrigated cropland, growing irrigated row and field crops, orchards and vineyards. Vegetation in uncultivated areas consists of annual grasses, forbs and scattered California White Oak.
DISTRIBUTION AND EXTENT: The Chuloak soils occur in the Northern San Joaquin Valley. The soils are not extensive in MLRA-17.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: San Joaquin County, California, l990.
REMARKS: The activity class was added to the classification in February of 2003.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the surface to a depth of 19 inches (Ap, A horizons)
Argillic horizon - The zone from 19 to 44 inches (Bt)