LOCATION PADRES                  CA

Established Series
RD: KLW/ENV/JHR/KJO/KP
01/2023

PADRES SERIES

The Padres series consists of very deep, well drained soils formed in alluvium from calcareous sedimentary rocks. Padres soils are on alluvial fans, alluvial flats and plains and have slopes of 0 to 9 percent. The mean annual precipitation is about 8 inches and the mean annual temperature is about 60 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Typic Calcixerepts

TYPICAL PEDON: Padres fine sandy loam - on a 2 percent slope under annual grasses and forbs at 2,120 feet elevation. (Colors are for dry soil unless otherwise stated. When described on April 7, 1981 the soil was dry to 10 inches and slightly moist below.)

A1 -- 0 to 3 inches; light brownish gray (2.5Y 6/2) sandy loam, dark grayish brown (2.5Y 4/2) moist; weak coarse platy structure; slightly hard, friable, nonsticky and slightly plastic; few very fine roots; few very fine discontinuous tubular pores; 5 percent gravel; electrical conductivity is 1.1 mmhos/cm; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (3 to 8 inches thick)

A2 -- 3 to 16 inches; light gray (2.5Y 7/2) sandy loam, dark grayish brown (2.5Y 4/2) moist; massive; slightly hard, friable, nonsticky and slightly plastic; common very fine roots; few very fine discontinuous tubular and interstitial pores; 5 percent gravel; electrical conductivity is 0.6 mmhos/cm.; violently effervescent; moderately alkaline (pH 8.0); gradual wavy boundary. (4 to 14 inches thick)

2Bk1 -- 16 to 30 inches; pale yellow (2.5Y 7/4) gravelly coarse sandy loam, light olive brown (2.5Y 5/4) moist; massive; soft and slightly hard, very friable and friable, nonsticky and nonplastic; few very fine roots; few very fine discontinuous tubular and common very fine and fine interstitial pores; 30 percent gravel; electrical conductivity is 2.0 mmhos/cm.; violently effervescent, carbonates segregated in spots as common fine filaments; moderately alkaline (pH 8.0); clear wavy boundary. (0 to 22 inches thick)

3Bk2 -- 30 to 38 inches; pale yellow (2.5Y 7/4) loam, light olive brown (2.5Y 5/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine discontinuous tubular pores; 5 percent gravel; electrical conductivity is 2.9 mmhos/cm; violently effervescent, carbonates segregated into common fine filaments; moderately alkaline (pH 8.0); gradual wavy boundary. (8 to 22 inches thick)

3Bk3 -- 38 to 46 inches; pale yellow (2.5Y 7/4) sandy loam, light olive brown (2.5Y 5/4) moist; massive; slightly hard, friable, nonsticky and slightly plastic; few very fine discontinuous tubular pores; 5 percent gravel; electrical conductivity is 2.9 mmhos/cm; violently effervescent, carbonates segregated into common fine filaments; moderately alkaline (pH 8.0) clear wavy boundary. (7 to 12 inches)

4Bk4 -- 46 to 62 inches; light gray (2.5Y 7/2) gravelly coarse sandy loam, light olive brown (2.5Y 5/4) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine discontinuous tubular and common very fine interstitial pores; 30 percent gravel; electrical conductivity is 3.2 mmhos/cm.; violently effervescent, carbonates segregated into few fine filaments; moderately alkaline (pH 8.0).

TYPE LOCATION: San Luis Obispo County, California; approximately 10.1 miles southeast on Simmler-Soda Lake Road from the intersection with Soda Lake-San Diego Creek Road, then approximately 1.5 miles southwest on dirt road just before fenced trail planting enclosure; then 539 feet from southeast corner post of abandoned soil well pump (magnetic bearing 130 degrees), 350 feet east and 110 feet south from the northwest corner of sec. 19, T. 31, S., R. 21 E. USGS Painted Rock topographic quadrangle; lat. 35 degrees, 13 minutes, 8 seconds N. and long. 119 degrees, 46 minutes, 15 seconds W.

RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 60 degrees to 68 degrees F. The moisture control section is moist in some part for at least 90 days from late December until April and is moist in all parts for 45 consecutive days between mid-January and mid-March. The soil is dry in all parts for about 225 days (see remarks). Soil temperature is always above 41 degrees F. Clay content ranges from 8 to 18 percent.

The A horizon has dry color of 10YR 6/2, 6/3, 2.5Y 6/2. 7/2 and moist color of 10YR 4/2, 4/3, 4/4, 5/4; 2.5Y 4/2, 4/4. It is sandy loam, fine sandy loam, and loam. Gravel content ranges from 0 to 15 percent and cobbles from 0 to 5 percent. It is slightly to violently effervescent. Some pedons are noncalcareous from 0 to 5 inches. Electrical conductivity ranges from 0.5 to 2.0 mmhos/cm. It is slightly to moderately alkaline.

The C horizon has dry color of 10YR 6/3, 6/4, 7/3, 7/4; 2.5Y 6/2, 7/2, 7/4 and moist color of 10YR 4/2, 4/3, 4/4, 5/4; 2.5Y 4/4, 5/4. It is gravelly coarse sandy loam, gravelly sandy loam, sandy loam, fine sandy loam and loam. Gravel content ranges from 0 to 35 percent and cobbles from 0 to 5 percent. It is strongly to violently effervescent. Electrical conductivity ranges from 2.0 to 4.0 mmhos/cm and increases with depth. Lithologic discontinuities are common, but are not present in some pedons.

COMPETING SERIES: These are the Hesperia, Polonio, San Timoteo and Zerker series in other families. There are no other series in this family. San Timoteo soils are moderately deep. Polonio and Zerker soils are fine-loamy. Hesperia soils are non-calcareous to a depth of 16 inches.

GEOGRAPHIC SETTING: Padres soils are on alluvial fans and plains and have slopes of 0 to 9 percent. The soils are formed in calcareous alluvium from sedimentary rocks. Elevations are 1,900 to 2,500 feet. The climate is semiarid with hot dry summers and cool moist winters. Mean annual precipitation is 7 to 10 inches. Average January temperature is about 46 degrees F; the average July temperature is about 77 degrees F, the mean annual temperature is about 58 degrees to 62 degrees F. The average frost-free season is about 175 to 250 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Polonio soils and the Beam (T) and Panorama (T) soils. Beam soils have a paralithic contact at a depth of 20 inches or less. Panorama soils are fine-loamy and have a paralithic contact at a depth of 20 to 40 inches.

DRAINAGE AND PERMEABILITY: Well drained, negligible to medium runoff, moderate permeability with moderately rapid permeability in the gravelly textured horizons.

USE AND VEGETATION: The soil is used for rangeland. Natural vegetation is mainly red brome, wild oats, filaree and fiddleneck.

DISTRIBUTION AND EXTENT: Elkhorn Plain and Carrizo Plain in California, MLRA 17. The soils are not extensive.

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

SERIES PROPOSED: San Luis Obispo County, California; Carrizo Plain Area, 1982. Soil name was derived from Los Padres National Forest.

REMARKS: Padres soils have xeric bordering on aridic moisture regime.

ADDITIONAL DATA: NSSL Pedon No. 84P 929

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National Cooperative Soil Survey
U.S.A.