Soil series profile

Cajon soil series

Cajon is a somewhat excessively drained soil with a loamy sand surface, mapped on 749,824 acres in 9 counties in CA. Hydrologic group A.

#296 by mapped area Typic Torripsamments (Entisols)

Drainage class: Somewhat excessively drained
Hydrologic group: A
Typical topsoil pH: 7.9
Mapped area: 750k

Typical Cajon profile

Texture and pH by depth

Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).

Show as a table

Typical Cajon horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–20 in (H1)	Loamy sand	7.9	4%	79%	0.75%
20–60 in (H2)	Gravelly loamy sand	7.9	3%	96%	0.25%

Representative values from the most extensive Cajon map unit (Cajon loamy sand, 0 to 5 percent slopes, survey area CA670). Other map units of this series vary within the series range.

Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Cajon soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Cajon soils is moderately alkaline: pH 7.9 (most land between 7.0 and 7.9). Acid-loving plants such as blueberries and azaleas struggle without amended beds, and some trees and shrubs show iron chlorosis (yellow leaves with green veins).

Sandy topsoil covers 94% of mapped Cajon acres. It drains fast and warms early in spring, but dries out and loses nutrients quickly: mulch, compost and steady watering help. The most common surface texture is loamy sand (40% of mapped Cajon acres).

95% of mapped Cajon acres is excessively or somewhat excessively drained: water moves through fast, so gardens need more frequent watering in dry spells.

For lawns and yards

93% of mapped acres is in hydrologic group A, where water soaks in fast. Lawns there dry out quickly; deeper, less frequent watering and organic matter help.

For a septic system

For conventional septic absorption fields, NRCS rates 89% of the acres in mapped Cajon soils very limited, 4% somewhat limited and 2% not limited (5% not rated, such as urban land, pits or water).

Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.

Flooding is mapped on 27% of the acres (<1% occasional, 0% frequent).

Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.

Generated from the mapped numbers above using fixed rules, not a site visit. See how these notes are written.

Where Cajon soil is found

Mapped acres

Cajon is mapped in California.

Counties with the most mapped Cajon soil
County	Acres	Share of county land
San Bernardino County, CA	393,642	7.3%
Kern County, CA	308,427	5.4%
Inyo County, CA	15,947	0.9%
Riverside County, CA	10,261	0.3%
Los Angeles County, CA	5,206	0.2%
Fresno County, CA	4,571	0.1%
San Diego County, CA	2,103	0.1%
Ventura County, CA	1,136	0.2%
Imperial County, CA	148	0.0%

Septic absorption fields

NRCS rating, share of Cajon acres

Not limited 2%

Somewhat limited 4%

Very limited 89%

Not rated 5%

Septic tank absorption field rating across mapped Cajon acres. Scale 0 to 100% of mapped land.

Show as a table

Septic tank absorption field rating across mapped Cajon acres.
Category	Share of acres
Not limited	2.2%
Somewhat limited	4.2%
Very limited	88.8%
Not rated	4.8%

Drainage, water table and flooding

Share of Cajon acres

Depth to seasonal high water table: None reported within about 6.5 feet (median where reported).
Flooding: Mapped as flooding on 27% of acres (<1% occasional, 0% frequent).
Slope: Typically 1–9% (median 4%).
Topsoil organic matter: Median 0.5%.

Drainage class

Excessively drained 16%

Somewhat excessively drained 80%

Well drained 0%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

Not rated 5%

Drainage class across mapped Cajon acres. Scale 0 to 100% of mapped land.

Show as a table

Drainage class across mapped Cajon acres.
Category	Share of acres
Excessively drained	15.5%
Somewhat excessively drained	79.7%
Well drained	0.0%
Moderately well drained	0.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%
Not rated	4.8%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 93%

B: moderate infiltration <1%

C: slow infiltration 0%

D: very slow infiltration (clayey, shallow or wet) 0%

A/D: D as is, A if drained 0%

B/D: D as is, B if drained 0%

C/D: D as is, C if drained 0%

Not rated 6%

Hydrologic soil group across mapped Cajon acres. Scale 0 to 100% of mapped land.

Show as a table

Hydrologic soil group across mapped Cajon acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	93.0%
B: moderate infiltration	0.6%
C: slow infiltration	0.0%
D: very slow infiltration (clayey, shallow or wet)	0.0%
A/D: D as is, A if drained	0.0%
B/D: D as is, B if drained	0.0%
C/D: D as is, C if drained	0.0%
Not rated	6.4%

Sources & data dates

Source: USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
Data date: SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
Scope: All map unit components named Cajon (component kind "Series") in SSURGO: 749,824 acres.
Method: Shares are by mapped acres of Cajon components. The profile comes from the single largest Cajon component. Full methodology.

Independent reference site. No government affiliation or endorsement.

Full narrative description: USDA Official Soil Series Description for Cajon.