LOCATION YOLO CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, thermic Mollic Xerofluvents
TYPICAL PEDON: Yolo silt loam - cultivated (Colors are for dry soil unless otherwise noted.)
Ap1--0 to 2 inches; Grayish brown (2.5Y 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate thick platy structure; hard, friable, slightly sticky, plastic; many very fine roots; many very fine interstitial and tubular pores; neutral (pH 6.7); abrupt wavy boundary. (2 to 10 inches thick)
Ap2--2 to 8 inches; Grayish brown (2.5Y 5/2) silt loam, dark brown (10YR 3/3) moist; massive; hard, friable, sticky, plastic; many very fine roots; common very fine tubular pores; neutral (pH 7.1); clear wavy boundary. (3 to 10 inches thick)
A1--8 to 19 inches; Grayish brown (2.5Y 5/2) silt loam, dark brown (10YR 3/3) rubbed, very dark grayish brown (10YR 3/2) coatings moist; weak coarse subangular blocky structure; hard, friable, slightly sticky, plastic; common very fine roots; many very fine tubular and clusters of interstitial pores associated with worm casts; few thin clay films on peds and continuous thin clay films in pores; neutral (pN 7.2); clear wavy boundary. 6 to 12 inches thick)
A2--19 to 26 inches; Grayish brown (2.5Y 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; massive; slightly hard, friable, slightly sticky, plastic; many very fine and few fine roots; many very fine tubular pores; neutral (pH 7.3); clear irregular boundary. (6 to 13 inches thick)
C1--26 to 33 inches; Brown (10YR 5/3) silt loam, olive brown (2.5Y 4/4) moist; massive; slightly hard, friable, slightly sticky, plastic; common very fine roots; common very fine tubular and clusters of interstitial pores associated with worm casts; mildly alkaline (pH 7.4); clear irregular boundary. (7 to 24 inches thick)
C2--33 to 41 inches; Pale brown (10YR 6/3) silt loam, olive brown (2.5Y 4/4) moist, dark grayish brown (2.5Y 4/2) stains in root channels moist; massive; soft, very friable, slightly sticky, slightly plastic; few very fine roots; common very fine tubular and many very fine interstitial pores; mildly alkaline (pH 7.4); abrupt wavy boundary. (8 to 30 inches thick)
Ab--41 to 58 inches; Grayish brown (2.5Y 5/2) silty clay loam, very dark grayish brown (2.5Y 3/2) moist; massive; slightly hard, friable, very sticky, plastic; few very fine roots; common very fine tubular pores; mildly alkaline (pH 7.4); clear wavy boundary. (0 to 8 inches thick)
C3--58 to 65 inches; Pale brown (10YR 6/3) silt loam, mottled olive brown (2.5Y 4/4) and olive (5Y 4/3) moist; massive; slightly hard, very friable, slightly sticky, slightly plastic; few very fine roots; many very fine tubular and interstitial pores; mildly alkaline (pH 7.5).
TYPE LOCATION: Yolo County, California; 90 feet east of center of field road, 3,150 feet west of State Highway 113 and 160 feet south of center of Hutchinson Drive, on the property of the University of California at Davis.
RANGE IN CHARACTERISTICS: The mean soil temperature ranges from about 60 degrees to 64 degrees F. and the soil temperature is continuously above 47 degrees F. Some or all parts of the 4 to 12-inch section become moist sometime in November and remain moist until sometime in May. The soils remain dry, unless irrigated, the rest of the year. Little or no gravel is present. The 10- to 40-inch section averages 20 to 35 percent clay and averages less than 15 percent material coarser than very fine sand. The A horizon is grayish brown, dark grayish brown and brown in hue of 10YR or 2.5Y and has value of 4 or 5 dry, 3 or 4 moist, and chroma of 2 or 3 dry and 2, 3, or 4 moist. The upper part of the A horizon ranges from loam or silt loam to silty clay loam and includes sandy loam. It is slightly acid or neutral. Organic matter is approximately 1.5 to 3 percent. The surface is massive or platy and is hard or very hard. The C horizon is pale brown, light yellowish brown, brown, dark grayish brown and grayish brown in 10YR or 2.5Y hue and has value of 4, 5, or 6 dry, 3 or 4 moist and chroma of 2 or 3 dry and 3 or 4 moist. It is usually silt loam or silty clay loam and has thin strata of loam, very fine sandy loam and fine sandy loam in some pedons. This horizon is dominantly slightly acid to mildly alkaline but some portions in some pedons include medium acid and moderately alkaline. Free lime is below depth of 40 inches in some pedons. A few thin clay films are present in some pedons. There is no significant weathering of primary minerals into clay size minerals.
COMPETING SERIES: These are the Balcom, Castaic, Garretson, Nocko, Reiff, Salinas, Sorrento, and Zamora series. Balcom and Castric soils are on shale and sandstone and have a paralithic contact at depths of less than 40 inches. Garretson soils have more than 15 percent material coarser than very fine sand. Nocho, Salinas, Sorrento and Reiff soils have less than 18 percent clay in the 10- to 40-inch section. Zamora soils have an argillic horizon.
GEOGRAPHIC SETTING: Yolo soils are on nearly level to moderately sloping alluvial fans. The soils formed in fine-loamy alluvium derived from sedimentary formations. They are at elevations of near sea level to 2400 feet in a dry subhumid, mesothermal climate having a mean annual rainfall of 12 to 40 inches with hot dry summers ant cool moist winters. The average January temperature is about 45 degrees F., average July temperature is about 75 degrees F., and the mean annual temperature is about 58 degrees to 63 degrees F. The average freeze-free season is about 220 to 300 days.
PRINCIPAL ASSOCIATED SOILS: These are the competing Reiff, Sorrento, and Zamora soils and the Arbuckle, Brentwood, Capay, Cole, Pleasanton, Soboba, and Sycamore soils. Arbuckle and Pleasanton soils are on older landscapes and have gravelly argillic horizons. Brentwood soils are fine-textured and have cambic horizons. Capay soils are fine-textured and have intersecting slickensides. Cole soils have thick mollic epipedons and fine argillic horizons. Soboba soils have more than 35 percent coarse fragments. Sycamore soils have mottles due to poor drainage within 20 inches of the surface.
DRAINAGE AND PERMEABILITY: Well-drained; slow to medium runoff; moderate permeability. Tillage pans have developed over broad areas and tend to restrict permeability.
USE AND VEGETATION: The soil is used for intensive row, field and orchard crops. Original vegetation was annual grasses, forbs, and some scattered oak.
DISTRIBUTION AND EXTENT: West site of Sacramento Valley, central California, and in the valleys of the California Coast Range. The series is extensive.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Woodland Area, California, 1909.
REMARKS: The Yolo soils were formerly classified as alluvial soils. The classification is changed from Typic Xerochrepts to Typic Xerorthents.
OSED scanned by SSQA. Last revised by state on 10/74.