The Pescadero series consists of poorly drained silty clays in basins. Slopes are less than 1 percent. The soils formed in alluvium from sedimentary rocks. Elevation ranges from 5 to 100 feet. Annual temperature is 60° F., annual rainfall is 16 to 19 inches, and the frost-free season is about 280 days. Vegetation is saltgrass, pickleweed, and other plants that tolerate salt. Pescadero soils are associated principally with Capay and Willows soils.
In a typical profile, the surface layer is light-gray silty clay loam about 3 inches thick. The subsoil is gray and mottled light olive-gray and pale-brown silty clay and silty clay loam about 64 inches thick. It is underlain by mottled pale-brown clay loam.
Pescadero soils are used for irrigated row crops, field crops, and irrigated pasture where reclaimed, and for dryland pasture, wildlife habitat, and recreation.
This soil occupies basins. Slopes are less than 1 percent. Representative profile in native pasture 0.3 mile south of Road 24 and .25 mile east of Road 102, in the SE¼ NW¼ NW¼ of sec. 2, T. 9 N., R. 2 E., Mount Diablo Base Meridian, 9 miles southeast of Woodland.
A1-0 to 3 inches, light-gray (2.5Y 7/2) silty clay loam; dark grayish brown (2.5Y 4/2) when moist; weak, medium, platy structure; very hard, friable, sticky and plastic; common micro random roots; common micro tubular pores; mildly alkaline (pH 7.7) on the immediate surface, moderately alkaline (pH 8.0) about one to three inches below the surface; abrupt, wavy boundary. (1 to 4 inches thick)
B21t-3 to 13 inches, gray (5Y 5/1) silty clay, very dark gray (5Y 3/1) when moist; strong, very coarse, prismatic structure; very hard, friable, sticky and plastic; common micro and many medium roots; many micro tubular pores; many moderately thick clay films on ped faces and in pores; strongly alkaline (pH 8.9); gradual, wavy boundary. (6 to 12) inches thick)
B22tca-13 to 26 inches, light olive-gray (5Y 6/2) silty clay; common, fine, distinct, strong-brown (7.5YR 5/6) and gray (N5/0) mottles; olive (5Y 4/3), dark brown (7.5YR 4/4), and very dark gray (N 3/0) when moist; moderate, medium, prismatic structure and moderate, medium and coarse, angular blocky structure; very hard, firm, sticky and plastic; common micro and many medium roots; common micro tubular pores; many moderately thick clay films on ped faces and in pores; slightly effervescent with segregated lime in soft masses; strongly alkaline (pH 8.6); clear, wavy boundary. (5 to 15 inches thick)
B23tca-26 to 40 inches, light olive-gray (5Y 6/2) silty clay; many, fine, distinct, strong-brown (7.5YR 5/6) mottles; olive gray (5Y 4/2) and has yellowish-red (5YR 4/6) and very dark grayish-brown (2.5YR 3/2) mottles when moist; moderate, medium, prismatic structure and moderate, medium and coarse, angular blocky structure; very hard, firm, sticky and plastic; few micro and common medium roots; many micro tubular pores; many moderately thick clay films in pores and continuous moderately thick clay films on ped faces; slightly effervescent with segregated lime in seams and soft masses; moderately alkaline (pH 8.1); gradual, wavy boundary. (7 to 15 inches thick)
B31ca-40 to 52 inches, light olive-gray (5Y 6/2) silty clay loam; many, fine, distinct, strong-brown (7.5YR 5/6) mottles; olive gray (5Y 4/2) and yellowish-red (5YR 4/6) mottles when moist; moderate, medium, prismatic structure and moderate, medium and coarse, angular blocky structure; hard, firm, sticky and plastic; few micro and fine roots; many micro tubular pores; continuous thin clay films on ped faces and many moderately thick clay films in pores; strongly effervescent with disseminated and segregated lime in seams; moderately alkaline (pH 7.9); gradual, wavy boundary. (9 to 15 inches thick)
B32ca-52 to 67 inches, pale-brown (10YR 6/3) silty clay loam; many, fine, distinct, strong-brown (7.5YR 5/8) mottles; brown (10YR 4/3) and has dark-brown (7.5YR 4/4) mottles when moist; strong, medium, prismatic structure and strong, medium and coarse, angular blocky structure; hard, friable, sticky and plastic; very few micro roots; many micro tubular pores; continuous thin clay films on ped faces and common thin clay films in pores; violently effervescent with lime segregated in seams; moderately alkaline (pH 8.0); gradual, wavy boundary. (8 to 15 inches thick)
Cca-67 to 72 inches, pale-brown (10YR 6/3) clay loam; many, fine, distinct, strong-brown (7.5YR 5/8) mottles; brown (10YR 4/3) and dark-brown (7.5YR 4/4) mottles when moist; moderate, medium, prismatic structure and strong, coarse, angular blocky structure; slightly hard, friable, sticky and plastic; many micro tubular pores; continuous thin clay films on ped faces; violently effervescent with lime segregated in seams; moderately alkaline (pH 8.1).
The A horizon ranges in color from light gray to pale brown and in texture from loam to silty clay. This horizon is medium acid to moderately alkaline. The Bt horizon ranges in color from gray to grayish brown to dark gray or light olive gray that has mottles, and in texture from silty clay to clay. This horizon is moderately alkaline to very strongly alkaline. The C horizon ranges in color from pale brown or very pale brown to light yellowish brown to pale olive that has mottles, and in texture from loam to silty clay loam.
Included in mapping are areas of Capay silty clay, Marvin silty clay loam, Riz loam, and Willows clay.
This Pescadero soil is slowly permeable. Surface runoff is very slow, and the erosion hazard is none to slight. The available water holding capacity is 4.0 to 6.0 inches in areas that have been drained. The effective rooting depth is 20 to 36 inches and is restricted by a high water table. Natural fertility is moderately high. The exchangeable sodium percentage is greater than 20 percent; the high content of sodium accounts for the lower water-holding capacity.
This soil is used mainly for dryland pasture. Other uses include rice, sugar beets, wildlife habitat, and recreation. Capability unit IVw-6, irrigated; VIw, non-irrigated.
This soil is similar to Pescadero silty clay, saline-alkali, except that it contains less than 15 percent exchangeable sodium. The surface layer is light olive gray. The subsoil is gray clay and is moderately alkaline. The substratum is mottled, light brownish-gray silty clay.
Included in mapping are small areas of Capay silty clay, Marvin silty clay loam, and Willows clay.
The available water holding capacity of this Pescadero soil is 5.0 to 8.0 inches for drained and reclaimed soil. The effective rooting depth is 30 to 48 inches and is limited by a water table.
This soil is used mainly for irrigated pasture, sugar beets, and rice. Other uses include wildlife habitat and recreation. Capability unit IIIw-5, irrigated; VIw, non-irrigated.
These soils are similar to Pescadero silty clay, saline-alkali, except that they are subject to flooding at least 1 year out of 3 because of flowage easements. In places on the surface they have 10 to 20 inches of overwash material that ranges in texture from sandy loam to silty clay. Included in mapping are small areas of Capay silty clay and Willows clay. Also included, in the vicinity of the Colusa Drainage Canal, are areas that are subject to flooding 1 year out of 2 for a duration of more than 48 hours.
These soils are in the Yolo By-Pass and are used mainly for rice and sugar beets. Other uses include wildlife habitat and recreation. Capability unit IVw-3, irrigated; VIw, non-irrigated.