Soil series profile

Mohall soil series

Mohall is a well drained soil with a sandy loam surface, mapped on 594,684 acres in 5 counties across 2 states. Hydrologic group C.

#437 by mapped area fine-loamy Typic Calciargids (Aridisols)

Drainage class: Well drained
Hydrologic group: C
Typical topsoil pH: 8.2
Mapped area: 595k

Typical Mohall 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).

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Typical Mohall horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–6 in (A)	Sandy loam	7.8	12%	68%	0.75%
6–20 in (Bt)	Clay loam	7.8	31%	35%	0.25%
20–60 in (Btk)	Clay loam	8.0	31%	35%	0.25%

Representative values from the most extensive Mohall map unit (Mohall-Trix complex, 0 to 1 percent slopes, survey area AZ703). 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 Mohall soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Mohall soils is moderately alkaline: pH 8.2 (most land between 7.8 and 8.8). 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).

Loamy topsoil (loam, silt loam and similar) covers 74% of mapped Mohall acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is sandy loam (41% of mapped Mohall acres).

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

For lawns and yards

On 97% 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 97% of the acres in mapped Mohall soils very limited, 3% somewhat limited and 0% 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 18% of the acres (2% 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 Mohall soil is found

Mapped acres

Mohall is mapped in Arizona and California.

Counties with the most mapped Mohall soil
County	Acres	Share of county land
Maricopa County, AZ	228,749	3.7%
Pinal County, AZ	152,341	4.7%
Pima County, AZ	135,429	2.6%
La Paz County, AZ	52,420	1.9%
Yuma County, AZ	9,042	0.4%

Septic absorption fields

NRCS rating, share of Mohall acres

Not limited 0%

Somewhat limited 3%

Very limited 97%

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

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Septic tank absorption field rating across mapped Mohall acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	2.7%
Very limited	97.3%

Drainage, water table and flooding

Share of Mohall acres

Depth to seasonal high water table: None reported within about 6.5 feet (median where reported).
Flooding: Mapped as flooding on 18% of acres (2% occasional, 0% frequent).
Slope: Typically 1–3% (median 1%).
Topsoil organic matter: Median 0.8%.

Drainage class

Excessively drained <1%

Somewhat excessively drained 0%

Well drained >99%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

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

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Drainage class across mapped Mohall acres.
Category	Share of acres
Excessively drained	0.5%
Somewhat excessively drained	0.0%
Well drained	99.5%
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 3%

C: slow infiltration 97%

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 Mohall acres. Scale 0 to 100% of mapped land.

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Hydrologic soil group across mapped Mohall acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	2.6%
C: slow infiltration	97.4%
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 Mohall (component kind "Series") in SSURGO: 594,684 acres.
Method: Shares are by mapped acres of Mohall components. The profile comes from the single largest Mohall component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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