Soil series profile

Marr soil series

Marr is a well drained soil with a fine sandy loam surface, mapped on 97,897 acres in 9 counties across 2 states. Hydrologic group B.

#3578 by mapped area fine-loamy Typic Hapludults (Ultisols)

Drainage class: Well drained
Hydrologic group: B
Typical topsoil pH: 5.1
Mapped area: 98k

Typical Marr 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 Marr horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–4 in (Ap)	Fine sandy loam	4.9	10%	67%	4.42%
4–25 in (Bt1)	Fine sandy loam	5.2	16%	53%	0.25%
25–57 in (Bt2)	Sandy clay loam	5.0	22%	70%	0.25%
57–76 in (BC)	Loamy fine sand	4.9	10%	84%	0.25%

Representative values from the most extensive Marr map unit (Grosstown-Marr-Hoghole complex, 15 to 40 percent slopes, survey area MD017). 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 Marr soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Marr soils is strongly acidic: pH 5.1 (most land between 4.9 and 5.1). Most vegetables and lawn grasses do best around 6.0 to 7.0, so lime is often needed; blueberries, azaleas and rhododendrons like it as it is.

Loamy topsoil (loam, silt loam and similar) covers 96% of mapped Marr acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is fine sandy loam (92% of mapped Marr acres).

100% of mapped Marr 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 96% of the acres in mapped Marr soils very limited, 0% somewhat limited and 0% not limited (4% 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.

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 Marr soil is found

Mapped acres

Marr is mapped in Maryland and Virginia.

Counties with the most mapped Marr soil
County	Acres	Share of county land
Prince George's County, MD	29,148	9.5%
Charles County, MD	25,399	8.7%
Anne Arundel County, MD	19,267	6.7%
Calvert County, MD	16,885	12.4%
St. Mary's County, MD	3,549	1.5%
King George County, VA	1,648	1.7%
Stafford County, VA	1,027	0.7%
Prince William County, VA	943	0.5%
Baltimore County, MD	32	0.0%

Septic absorption fields

NRCS rating, share of Marr acres

Not limited 0%

Somewhat limited 0%

Very limited 96%

Not rated 4%

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

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Septic tank absorption field rating across mapped Marr acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	96.1%
Not rated	3.9%

Drainage, water table and flooding

Share of Marr acres

Depth to seasonal high water table: About 5.9 feet (71 in) (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 3–28% (median 13%).
Topsoil organic matter: Median 4.4%.

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

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Drainage class across mapped Marr 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 100%

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%

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

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

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 Marr (component kind "Series") in SSURGO: 97,897 acres.
Method: Shares are by mapped acres of Marr components. The profile comes from the single largest Marr component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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