Established Series


The Balcom series consists of moderately deep, well drained soils that formed in material that weathered from soft, calcareous shale and sandstone. Balcom soils are on hills and have slopes of 5 to 75 percent. The mean annual precipitation is about 18 inches and the mean annual air temperature is about 61 degrees F.

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

TYPICAL PEDON: Balcom loam, annual grass range. (Colors are for dry soil unless otherwise noted.)

A--0 to 8 inches; grayish brown (2.5Y 5/2) loam, dark grayish brown (2.5Y 4/2) moist; moderate coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine roots; common very fine tubular pores; strongly effervescent, carbonates disseminated; moderately alkaline (pH 8.0); clear smooth boundary. (6 to 14 inches thick)

Bk--8 to 23 inches; light brownish gray (2.5Y 6/2) loam, dark grayish brown (2.5Y 4/2) moist; weak coarse subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine roots; few very fine tubular pores; violently effervescent, carbonates disseminated and segregated as many fine, masses and filaments; moderately alkaline (pH 8.0); clear broken boundary. (6 to 28 inches thick)

Cr--23 to 60 inches; pale olive (5Y 6/3) shale that crushes to loam, olive (5Y 5/3) moist; massive; hard, violently effervescent, carbonates disseminated, and segregated as many fine filaments on shale fragments; moderately alkaline (pH 8.0).

TYPE LOCATION: Ventura County, California; approximately 200 feet south and 50 feet west of the NE corner, sec. 30, T. 3 N., R. 20 W.

RANGE IN CHARACTERISTICS: Depth to a paralithic contact of soft shale or sandstone is 20 to 40 inches. The mean annual soil temperature is about 64 degrees F. and the soil temperature usually is not below 47 degrees F. at any time. The soil between depths of about 5 and 15 inches is usually dry all of the time from mid-April or May until late November or early December and is moist in some or all parts all the rest of the year. Rock fragments consist of small pieces of shale that are easily crushed. Fragments are usually less than 10 percent and are no more than 35 percent. The soil profile is loam, silt loam, clay loam or silty clay loam in all parts and has more than 15 percent fine sand or coarser. It is slightly to violently effervescent throughout except in some pedons the upper few inches are not effervescent. Carbonate segregations range from a few small filaments to many seams, masses and blotches.

The A horizon is 2.5Y 5/2, 5/3, 6/2, 6/3, 6/4, 7/2; 10Y 6/1, 6/2, 6/3, 6/4, 7/2, 7/3, 7/4, and moist color is 10YR 5/3, 5/2, 4/3, 4/2. In some pedons the upper part of the A horizon is one unit value darker than the Bk horizon. Organic matter is less than 1 percent.

The Bk horizon is 2.5Y 4/3, 5/2, 5/3, 6/2, 6/3, 6/4, 7/2; 10YR 6/1, 6/2, 6/3, 6/4, 7/2, 7/3, 7/4. Calcium carbonate equivalent is 15 to 25 percent. In some pedons it is one unit darker than the underlying Cr horizon.

COMPETING SERIES: These are the Chaqua and Calla series. Calla soils lack a paralithic contact. Chaqua soils have a paralithic contact below 40 inches.

GEOGRAPHIC SETTING: Balcom soils are on rounded hills at elevations of 200 to 2,300 feet. Slopes range from 5 to 75 percent. The soils formed in material weathered from gray, soft, calcareous shale and sandstone. The climate is dry subhumid mesothermal with warm dry summers and cool moist winters. Mean annual precipitation is 10 to 22 inches. Average January temperature is 53 degrees F., average July temperature is 68 degrees F., and mean annual temperature is 58 degrees to 63 degrees F. The freeze-free season is 175 to 350 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Castaic, Dibble, Linne, Mocho, Newville and Saugus soils. Castaic soils are noncalcareous in all parts above a depth of 20 inches. Dibble and Newville soils have argillic horizons. Linne soils have mollic epipedons. Mocho soils are in the valleys and have mollic epipedons. Saugus soils have less than 18 percent clay throughout the profile.

DRAINAGE AND PERMEABILITY: Well drained; low to high runoff; moderate to moderately slow permeability.

USE AND VEGETATION: Used primarily for range, wildlife and watershed. Natural vegetation is annual grasses and mustard.

DISTRIBUTION AND EXTENT: Coast range mountains in south-central California and on the west side of Sacramento Valley. MLRAs 15 and 20. The series is moderately extensive.


SERIES ESTABLISHED: Ventura County, California, 1971.

REMARKS: Original concept of the series has a calcic horizon. Soils without a calcic horizon should be reviewed and considered with a new series.

National Cooperative Soil Survey