LOCATION ZACA CA

Established Series
Rev. RDE/GMK/RLR
12/2011

ZACA SERIES

The soils of the Zaca series are deep, well-drained soils formed in material from weakly consolidated marine sediments. They are on gently rolling to very steep slopes. The mean annual precipitation is about 18 inches (457 millimeters) and the mean annual temperature is about 60 degrees F (16 degrees C). Slopes are 5 to 75 percent.

TAXONOMIC CLASS: Fine, smectitic, thermic Vertic Haploxerolls

TYPICAL PEDON: Zaca clay, cultivated. (Colors are for dry soil unless otherwise noted.

Ap--0 to 10 cm, (0 to 4 inches); very dark gray (10YR 3/1) clay very dark gray (10YR 3/1) when moist; strong, fine and medium, granular structure; very hard, friable, very sticky and very plastic; common very fine roots; many very fine interstitial pores; moderately alkaline (pH 8.0); slightly effervescent with lime disseminated; clear, smooth boundary. 1 to 4 inches thick.

A--10 to 41 cm, (4 to 16 inches); very dark gray (10YR 3/1) clay, very dark gray (10YR 3/1) when moist; strong, medium and coarse, subangular blocky and weak, fine, granular structure; very hard, friable, very sticky and very plastic; many very fine roots; many very fine interstitial and few very fine tubular pores; moderately alkaline (pH 8.0); strongly effervescent with lime disseminated; gradual, wavy boundary. 10 to 16 inches thick.

Bss--41 to 91 cm, (16 to 36 inches); very dark gray (10YR 3/1) clay, very dark gray (10YR 3/1) when moist; strong, fine, subangular blocky and medium, fine, granular structure; very hard, friable, very sticky and very plastic; common very fine roots; many very fine interstitial and few very fine tubular pores; moderately alkaline (pH 8.0); slightly effervescent with lime disseminated; many slickensides on peds; clear, irregular boundary. 9 to 25 inches thick.

Bk--91 to 137 cm, (36 to 54 inches); mixed very dark grayish brown 10YR 3/2) and yellowish brown (10YR 5/4) silty clay, very dark brown (10YR 2/2) and dark yellowish brown (10YR 4/4) when moist; moderate, fine, subangular blocky and moderate, fine, granular structure, hard, friable, very sticky and plastic; few very fine roots; many very fine interstitial pores; moderately alkaline (pH 8.0); violently effervescent with lime disseminated and segregated in large irregularly shaped soft masses; clear, wavy boundary. 20 to 25 inches thick.

Cr--137 to 200 cm, (54 to 72 inches); yellowish brown (10YR 5/4) softly consolidated mudstone that crushes to sandy clay loam, dark yellowish brown (10YR 4/4) when moist; massive; hard, friable, sticky and plastic; no roots; many very fine interstitial pores; moderately alkaline (pH 8.0); violently effervescent with lime segregated in medium irregularly shaped soft masses.

TYPE LOCATION: San Luis Obispo County, California; in Nipomo Valley about 1,550 feet north and 3,100 feet east of the intersection of Thompson Avenue and Mehlaschu Road, T.11N., R.34W.

RANGE IN CHARACTERISTICS:
Depth to a paralithic contact: 40 to 65 inches (100 to 165 cm) from softly consolidated marine sediments
Mean annual soil temperature: 60 degrees to 64 degrees F (16 to 18 degrees C), and usually is not below 47 degrees F. at any time. The soil between depths of 4 to 12 inches is usually dry all of the time from May until November and is moist in some or all parts all the rest of the year.
Cracks: more than 1 cm wide to a depth of 20 inches or more when dry and lacks intersecting slickensides.
Reaction: slightly to strongly effervescent in their upper horizons and violently effervescent in their lower
horizons.

A, Ap horizon:
Moist Colors: hue of 10YR or 2.5Y; value of 2 to 5; chroma of 2 or less
Texture: clay or silty clay

Bkss, Bss, Bk horizon:
Moist Colors: hue of 10YR or 2.5Y; value of 2 to 5; chroma or 1 to 4
Textures: clay or silty clay
Carbonates: finely disseminated and/or masses on faces of all peds

C(k) horizon:
Moist Colors: hue of 10YR or 2.5Y; value of 3 to 5; chroma of 1 to 4
Teture: clay, clay loam, silty clay, silty clay loam

Cr, Crk horizon: extremely weakly to moderately weakly cemented marine sediments

COMPETING SERIES: These are the Carbona and Deldota soils. Carbone soils are on alluvial terraces with source material from weathered from sedimentaty, metasedimentary, and igneous rocks. Deldota soils are alluvial and are somewhat poorly drained.

GEOGRAPHIC SETTING: Zaca soils are 5 to 75 percent slopes are on gently rolling to very steep landscape positions at elevations of 200 to 2,000 feet (60 to 610 meters). They formed in softly consolidated marine sediments of mudstone, sandstone and shale. The climate is subhumid mesothermal with warm dry summers and moist cool winters. Mean annual precipitation is 11 to 31 inches (280 to 838 millimeters). Average January temperature is 50 degrees F (10 degrees C).; average July temperature is 67 to 72 degrees F (19 to 22 degrees C).; mean annual temperature is 58 to 62 degrees F (14 to 17 degrees C). The frost-free season is 300 to 365 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ayar, Diablo, Linne, Nacimiento, and Santa Lucia series. Ayar soils have intersecting slickensides and chroma of 2 or more in the A horizon. Diablo soils have noncalcareous surface horizons and have intersecting slickensides. Linne soils are less than 40 inches deep to a paralithic contact and do not crack widely upon drying. Nacimiento soils have 25 to 35 percent clay and are less than 40 inches deep to paralithic contact. Santa Lucia soils have a lithic contact at depths of 20 to 40 inches and have more than 35 percent coarse fragments.

DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.

USE AND VEGETATION: Used for range, dryland grain and beans, irrigated orchards, and for urban development. The native vegetation is annual grasses and forbs.

DISTRIBUTION AND EXTENT: Scattered throughout the coast range in central and southern California. The soils are of moderate extent. MlRA 15 and hills in MLRA 19

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Santa Barbara County (Santa Ynez Area), California, 1927.

REMARKS: The Zaca soils were formerly classified as Rendzinas or Grumusols with some characteristics of Rendzinas. The type location has been moved back to San Luis Obispo County because it is more extensive in this locality.

OSED scanned by SSQA. Last revised by state on 9/74, 11/2011.

National Cooperative Soil Survey
U.S.A.