Soil series profile

Duffau soil series

Duffau is a well drained soil with a fine sandy loam surface, mapped on 245,756 acres in 19 counties across 2 states. Hydrologic group B.

#1436 by mapped area fine-loamy Udic Paleustalfs (Alfisols)

Drainage class: Well drained
Hydrologic group: B
Typical topsoil pH: 6.9
Mapped area: 246k

Typical Duffau 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 Duffau horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–2 in (A)	Fine sandy loam	7.0	12%	67%	0.5%
2–70 in (Bt)	Sandy clay loam	6.5	26%	57%	0.75%
70–80 in (BC)	Sandy clay loam	7.0	25%	57%	0.25%

Representative values from the most extensive Duffau map unit (Windthorst and Duffau soils, 2 to 8 percent slopes, severely eroded, survey area TX337). 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 Duffau soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Duffau soils is neutral: pH 6.9 (most land between 6.5 and 7.3), the range most vegetables, flowers and lawn grasses prefer.

Sandy topsoil covers 60% of mapped Duffau 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 (59% of mapped Duffau acres).

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

For lawns and yards

Most land is in hydrologic groups B and C, where rain soaks in at a moderate pace.

For a septic system

For conventional septic absorption fields, NRCS rates 13% of the acres in mapped Duffau soils very limited, 71% somewhat limited and 0% not limited (15% not rated, such as urban land, pits or water).

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 Duffau soil is found

Mapped acres

Duffau is mapped in Texas and Oklahoma.

Counties with the most mapped Duffau soil
County	Acres	Share of county land
Montague County, TX	69,400	11.7%
Wise County, TX	62,740	10.9%
Parker County, TX	45,706	7.9%
Carter County, OK	18,588	3.5%
Cooke County, TX	14,126	2.5%
Erath County, TX	13,856	2.0%
Jack County, TX	7,339	1.3%
Hood County, TX	4,794	1.8%
Love County, OK	3,709	1.1%
Somervell County, TX	2,364	2.0%
Tarrant County, TX	1,680	0.3%
Hamilton County, TX	495	0.1%
Coryell County, TX	445	0.1%
Comanche County, TX	205	0.0%
Bosque County, TX	140	0.0%
Eastland County, TX	87	0.0%
Brown County, TX	44	0.0%
Lampasas County, TX	34	0.0%
Mills County, TX	3	0.0%

Septic absorption fields

NRCS rating, share of Duffau acres

Not limited 0%

Somewhat limited 71%

Very limited 13%

Not rated 15%

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

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Septic tank absorption field rating across mapped Duffau acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	71.3%
Very limited	13.3%
Not rated	15.4%

Drainage, water table and flooding

Share of Duffau acres

Depth to seasonal high water table: None reported within about 6.5 feet (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 2–6% (median 4%).
Topsoil organic matter: Median 1.6%.

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

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Drainage class across mapped Duffau 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 86%

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 15%

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

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Hydrologic soil group across mapped Duffau acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	85.5%
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	14.5%

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 Duffau (component kind "Series") in SSURGO: 245,756 acres.
Method: Shares are by mapped acres of Duffau components. The profile comes from the single largest Duffau component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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