LOCATION AMADOR CA

Established Series
Rev. AJT/WBS/DJE/ET/AGB/TKK/JW
10/2018

AMADOR SERIES

The Amador series consists of shallow, well drained soils formed in material weathered from weakly consolidated acidic tuff (rhyolitic). These soils are on hills with mound and swale microrelief and on backslopes of hills. These soils are on the mound position. Slopes are 2 to 50 percent. The annual precipitation is about 460 mm and the temperature is about 17 degrees C.

TAXONOMIC CLASS: Loamy, mixed, superactive, thermic, shallow Typic Haploxerepts

TYPICAL PEDON: Amador loam on a convex mound on a southeast facing, complex slope of 5 percent under annual grasses and forbs at an elevation of 60 meters. (Colors are for dry soil unless otherwise noted. When described on November 28, 1979, the soil was moist throughout.)

A--0 to 15 cm; light gray (10YR 7/2) loam, dark grayish brown (10YR 4/2) moist; moderate coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine and few fine tubular and many very fine interstitial pores; 10 percent gravel; strongly acid (pH 5.1); clear wavy boundary. (3 to 20 cm thick)

Bw1--15 to 28 cm; light gray (10YR 7/2) loam, brown (10YR 5/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine and common fine tubular and many very fine interstitial pores; 5 percent gravel; strongly acid (pH 5.1); clear wavy boundary.

Bw2--28 to 48 cm; light gray (10YR 7/2) loam, brown (10YR 5/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and common fine tubular and many very fine interstitial pores; few thin colloidal stains on mineral grains, 10 percent gravel mostly at the base of horizon; very strongly acid (pH 5.0); abrupt wavy boundary. (Combined thickness of the Bw horizons is 23 to 41 cm)

Cr--48 to 56 cm; pale yellow (2.5Y 8/2) weakly consolidated rhyolitic tuffaceous sediments, pale yellow (2.5Y 7/4) moist; very strongly acid (pH 4.5).

TYPE LOCATION: Sacramento County, California; 6.5 km (4.1 miles) southeast of Bridgehouse, 1.6 km (1.0 mile) northwest along Meiss Road from the Ione Road intersection, and 85 meters (285 feet) north of Meiss Road, 1,420 feet south and 1,870 feet east of the northwest corner of sec. 26, T. 7 N., R. 8 E. USGS 7.5 minute topographic quadrangle: Carbondale, California. WGS84 38.4342141 latitude and -121.0697555 longitude. UTM Zone 10 673742 meters East, 4217281 meters N, NAD83.

RANGE IN CHARACTERISTICS:

Soil temperature: The mean annual soil temperature at the paralithic contact is 18 to 19 degrees C and the temperature remains above 8 degrees C throughout the year. The difference between mean summer and mean winter soil temperature is greater than 6 degrees C. The soils have a thermic temperature regime.

Soil moisture: The soil moisture control section is dry in all parts from about May to October. The soils have a xeric moisture regime.

Diagnostic Feature(s):
Ochric epipedon thickness: 3 to 20 cm
Cambic horizon thickness: 23 to 41 cm
Depth to paralithic contact: 25 to 50 cm

Particle size control section weighted average:
Clay content: 12 to 25 percent
Rock fragments: 0 to 15 percent

Base saturation by sum of cations is 60 to 85 percent throughout.

A horizon
Hue: 10YR, 7.5YR
Value: 6 or 7 dry, 3 to 5 moist
Chroma: 1 to 4 dry, 2 to 4 moist
Texture: sandy loam, loam
Clay content: 10 to 25 percent
Rock fragments: 0 to 20 percent gravel
Reaction: strongly acid to slightly acid

Bw horizon
Hue: 10YR, 7.5YR
Value: 6 or 7 dry; 4 or 5 moist
Chroma: 2 to 4 dry or moist
Texture: sandy loam, loam
Clay content: 12 to 27 percent (1 to 3 percent more than A horizon)
Rock fragments: 0 to 25 percent gravel
Reaction: very strongly acid to moderately acid

Cr horizon
Hue: 10YR, 2.5Y, 5Y
Value: 5 to 8 dry or moist
Chroma: 2 to 4 dry or moist

COMPETING SERIES: These are the Borreguero (MLRA 15), Osito (MLRA 20) and Wolfey (MLRA 15) series. The Borreguero, Osito, and Wolfey soils do not have glass in any part of the control section. Osito soils are neutral to slightly alkaline.

GEOGRAPHIC SETTING: The Amador soils are on hills and backslopes of hills. Slopes are 2 to 50 percent. On hills with slopes of less than 15 percent, there is mound and swale microrelief with Amador soils occupying the mound position. Elevation is 40 to 200 meters. These soils formed in material weathered from weakly consolidated rhyolitic tuffaceous sediments of the Valley Springs formation. The climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation is 365 to 570 mm. Mean annual air temperature is about 17 degrees C; average January temperature is about 8 degrees C and average July temperature is about 25 degrees C. Frost-free period is 310 to 350 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gillender, Hadselville, Pardee, Pentz and Vleck soils. Gillender soils do not have cambic horizons and are in intermound, or swale, positions. Hadselville and Pentz soils have a mollic epipedon and occur on andesitic parent materials. Pardee soils have anargillic horizon, greater than 35 percent rock fragments in the particle size control section, and occur on eroded fan remnants. Vleck soils have greater than 35 percent clay in the particle size control section and occur in concave footslope and toeslope positions.

DRAINAGE AND PERMEABILITY: Well drained; moderately high to high saturated hydraulic conductivity. The saturated hydraulic conductivity of the bedrock is low to moderately high.

USE AND VEGETATION: These soils are used for livestock grazing. Vegetation is annual grasses and forbs such as soft chess, ripgut brome and foxtail fescue.

DISTRIBUTION AND EXTENT: Sierra Nevada Foothills of California; MLRA 18. The series is moderately extensive.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Stockton Area, California, San Joaquin County, 1939. Source of the name is Amador County.

REMARKS:

Particle Size Control Section for this pedon: 25 to 48 cm

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon 0 to 15cm
Cambic horizon 15 to 48 cm
Paralithic contact 48 cm

These soils were formerly classified as being Dystric. Subsequent lab data (Hach) indicates base saturation of more than 60 percent. The type location was moved from Merced County to Sacramento County to better reflect the cambic horizon which is typical for these Inceptisols. The former type location lacked the cambic horizon.

Laboratory data for Pedon ID: S04CA099-003 (taxadjunct) indicates the presence of volcanic glass throughout the control section and it is inferred that this is a common situation in the soils formed from this parent material.

Gravel size fragments slake in water.

ADDITIONAL DATA:

NASIS User Pedon ID: 1987CA067003

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.

National Cooperative Soil Survey
U.S.A.