Established Series


The Sierra series is a member of the fine-loamy, mixed, thermic family of Ultic Haploxeralfs. Typically, Sierra soils have brown, moderately acid, coarse sandy loam A horizons that grade to yellowish red and red, slightly acid, heavy loam and clay loam B2t horizons grading to strongly weathered acid igneous bedrock.

TAXONOMIC CLASS: Fine-loamy, mixed, active, thermic Ultic Haploxeralfs

TYPICAL PEDON: Sierra coarse sandy loam - cultivated. (Colors are for dry soil unless otherwise noted.)

Ap--0 to 8 inches; brown (7.5YR 5/4) coarse sandy loam, dark reddish brown (5YR 3/4) moist; massive; slightly hard, friable; many very fine roots; many very fine and fine pores; moderately acid (pH 5.7); clear smooth boundary. (5 to 15 inches thick)

Blt--8 to 18 inches; reddish brown (5YR 5/4) loam, yellowish red (5YR 3/6) moist; massive; hard, friable, slightly sticky, slightly plastic; many very fine roots; many very fine, common fine, few medium and coarse pores; few thin discontinuous clay films line pores, colloids mainly bridging mineral grains; moderately acid (pH 5.9); gradual smooth boundary. (5 to 11 inches thick)

B21t--18 to 27 inches; yellowish red (5YR 5/6) heavy loam, dark red (2.5YR 3/6) moist; massive; very hard, firm, slightly sticky, slightly plastic; common very fine roots; few medium coarse pores; clay films are thin and nearly continuous; slightly acid (pH 6.2); gradual smooth boundary. (6 to 11 inches thick)

B22t--27 to 48 inches; red (2.5YR 5/6) clay loam, dark red (2.5YR 3/6) moist; massive; very hard, firm, sticky, plastic; common very fine roots- common very fine, few fine pores; moderately thick continuous clay films line most pores and as bridges between sand grains; slightly acid (pH 6.5); gradual smooth boundary. (9 to 30 inches thick)

B3t--48 to 68 inches; yellowish red (5YR 5/8) loam, dark red (2.5YR 3/8) moist; massive; very hard, firm, sticky, plastic; few very fine roots; common very fine and few fine pores; thin continuous clay films line some pores and as bridges between sand grains; slightly acid (pH 6.5); clear irregular boundary. (14 to 21 inches thick)

C--68 to 78 inches; yellowish red (5YR 5/8) weathered granite that textures fine sandy loam, yellowish red (5YR 3/8) moist, dark red (2.5YR 3/8 dry or moist) coatings; massive; original granitic structure is evident; hard, friable; thin discontinuous clay films along parting planes; slightly acid (pH 6.5).

TYPE LOCATION: Amador County, California; approximately 2 1/4 miles northwest of Fiddletown, 1/2 mile south of the Shenandoah School on the Shenandoah School road in SW1/4 SW1/4 sec. 29, T.8N., R.llE.

RANGE IN CHARACTERISTICS: Depth to a paralithic contact of weathered granitic rock is 40 to 80 inches. The solum is 40 to 80 inches thick. Mean annual soil temperature at a depth of 20 inches is about 60 degrees to 67 degrees F. Between depths of about 6 to 20 inches the soils are usually continually moist but become dry in all parts between May 10 and June 10 and remain dry until sometime in October. Coarse fragments make up about 2 to 15 percent of the solum and are mostly 2 to 5 mm. in size.

The A horizon is grayish brown, dark grayish brown or brown in 10YR or 7.5YR hue, but can have a hue of 5YR moist. It has moist value of 3 in all parts or only in the upper 5 to 9 inches. It has moist chroma of 4 or more below 5 to 9 inches. It has 2.5 to 6 percent organic matter in the upper few inches and above 1.0 to 1.5 percent to a depth of 10 inches. It is coarse sandy loam, sandy loam or loam. It is neutral to strongly acid. Its lower boundary is gradual or there is a transitional horizon.

The B2t horizon is red, yellowish red, or reddish yellow in 5YR or 2.5YR hue. Moist values are 2 units darker than the dry values or hues are 5YR in some part. The B2t horizon is heavy loam, clay loam, or sandy clay loam with 15 to 25 percent combined coarse and very coarse sand. It is slightly to strongly acid. It has 50 to 75 percent base saturation in the upper 30 inches of the argillic horizon, increasing to 80 percent below this depth in some pedons.

COMPETING SERIES: These are the Auberry, Butte, Coarsegold, Churn, Coombs, Fallbrook, Musick, Rescue, Willits, and Wisheylu soils. Auberry, Butte, Churn, Coombs, Willits and Wisheylu soils have no hues redder than 7.5YR dry. Coarsegold, Fallbrook and Rescue soils have 75 to 100 percent base saturation in all parts of the argillic horizon. Musick soils have a mean annual soil temperature of 51 degrees to 58 degrees F.

GEOGRAPHIC SETTING: The soils occur on gently sloping to very steep relief along the western footslopes of the Sierra Nevada Mountains at elevations of 200 to 3,500 feet. The soils formed in residuum from granitic rocks. Rock outcrops occur in some areas. The climate is subhumid mesothermal with hot dry summers and cool moist winters. Mean annual precipitation is 20 to 38 inches. The average January temperature is 42 degrees to 46 degrees F., average July temperature is 72 degrees to 76 degrees F., the mean annual temperature is about 59 degrees to 62 degrees F. Frost-free season is 180 to 260 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ahwahnee, Auburn and Whiterock soils and the competing Auberry soils. Ahwahnee soils have less than 18 percent clay in the argillic horizon. Auburn and Whiterock soils have hard rock within 20 inches of the surface in some or all portions of the pedon respectively.

DRAINAGE AND PERMEABILITY: Well-drained; slow to rapid turnoff; moderately slow permeability.

USE AND VEGETATION: Used for growing grain, grain hay and pasture and a few dryland orchards and vineyards. Under irrigation used for orchards, pasture and hay. Natural vegetation is annual weeds and grasses with scattered oaks, digger pine and ponderosa pine.

DISTRIBUTION AND EXTENT: Mainly in the foothills of the Sierra Nevada Mountains from Shasta County south to Tulare County in California. The soils are moderately extensive.


SERIES ESTABLISHED: Fresno Area, California, 1900.

REMARKS: The Sierra soils were formerly classified as Noncalcic Brown soils.

The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET

OSED scanned by SSQA. Last revised by state on 4/71.

National Cooperative Soil Survey