Soil series profile

Casa Grande soil series

Casa Grande is a well drained soil with a fine sandy loam surface, mapped on 329,087 acres in 5 counties in AZ. Hydrologic group C.

#1001 by mapped area fine-loamy Typic Natrargids (Aridisols)

Drainage class: Well drained
Hydrologic group: C
Typical topsoil pH: 8.4
Mapped area: 329k

Typical Casa Grande 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 Casa Grande horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–13 in (Ap)	Fine sandy loam	8.4	12%	70%	0.75%
13–23 in (Btknz)	Sandy clay loam	8.6	30%	56%	0.25%
23–28 in (Btkknz1)	Sandy clay loam	8.8	30%	56%	0.25%
28–49 in (Btkknz2)	Sandy clay loam	8.8	30%	56%	0.25%
49–60 in (2Bkknz)	Sandy clay loam	8.8	30%	56%	0.25%

Representative values from the most extensive Casa Grande map unit (Casa Grande fine sandy loam, 0 to 3 percent slopes, survey area AZ659). 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 Casa Grande soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Casa Grande soils is moderately alkaline: pH 8.4 (most land between 7.6 and 8.5). 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 52% of mapped Casa Grande 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 fine sandy loam (46% of mapped Casa Grande acres).

100% of mapped Casa Grande acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

On 100% of mapped acres, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.

For a septic system

For conventional septic absorption fields, NRCS rates 68% of the acres in mapped Casa Grande soils very limited, 4% somewhat limited and 28% not limited.

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 25% of the acres (0% 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 Casa Grande soil is found

Mapped acres

Casa Grande is mapped in Arizona.

Counties with the most mapped Casa Grande soil
County	Acres	Share of county land
Pinal County, AZ	132,299	4.1%
Maricopa County, AZ	96,080	1.5%
Pima County, AZ	80,801	1.6%
La Paz County, AZ	13,589	0.5%
Yuma County, AZ	50	0.0%

Septic absorption fields

NRCS rating, share of Casa Grande acres

Not limited 28%

Somewhat limited 4%

Very limited 68%

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

Show as a table

Septic tank absorption field rating across mapped Casa Grande acres.
Category	Share of acres
Not limited	27.9%
Somewhat limited	4.1%
Very limited	67.9%

Drainage, water table and flooding

Share of Casa Grande acres

Depth to seasonal high water table: None reported within about 6.5 feet (median where reported).
Flooding: Mapped as flooding on 25% of acres (0% occasional, 0% frequent).
Slope: Typically 1–2% (median 1%).
Topsoil organic matter: Median 0.8%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 100%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

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

Show as a table

Drainage class across mapped Casa Grande acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	100.0%
Moderately well drained	0.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%

B: moderate infiltration 0%

C: slow infiltration 100%

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%

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

Show as a table

Hydrologic soil group across mapped Casa Grande acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	0.0%
C: slow infiltration	100.0%
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%

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 Casa Grande (component kind "Series") in SSURGO: 329,087 acres.
Method: Shares are by mapped acres of Casa Grande components. The profile comes from the single largest Casa Grande component. Full methodology.

Independent reference site. No government affiliation or endorsement.

Full narrative description: USDA Official Soil Series Description for Casa Grande.