Soil series profile

Grosstown soil series

Grosstown is a well drained soil with a gravelly silt loam surface, mapped on 47,407 acres in 5 counties in MD. Hydrologic group A.

#6180 by mapped area coarse-loamy Typic Hapludults (Ultisols)

Drainage class: Well drained
Hydrologic group: A
Typical topsoil pH: 4.1
Mapped area: 47k

Typical Grosstown 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 Grosstown horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–4 in (Ap)	Gravelly silt loam	4.1	12%	24%	4%
4–20 in (Bt1)	Silt loam	4.5	14%	22%	1%
20–26 in (Bt2)	Gravelly loam	4.7	23%	31%	0.4%
26–71 in (2Bt3)	Extremely gravelly silt loam	4.9	16%	22%	0.1%
71–80 in (3BC)	Extremely gravelly coarse sand	5.0	4%	90%	0%

Representative values from the most extensive Grosstown 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 Grosstown soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Grosstown soils is extremely acidic: pH 4.1. 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 99% of mapped Grosstown acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is gravelly silt loam (99% of mapped Grosstown acres).

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

For lawns and yards

81% 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 99% of the acres in mapped Grosstown soils very limited, 0% somewhat limited and 0% not limited (1% 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 Grosstown soil is found

Mapped acres

Grosstown is mapped in Maryland.

Counties with the most mapped Grosstown soil
County	Acres	Share of county land
Charles County, MD	35,977	12.3%
Prince George's County, MD	8,585	2.8%
St. Mary's County, MD	2,419	1.0%
Baltimore County, MD	231	0.1%
Harford County, MD	194	0.1%

Septic absorption fields

NRCS rating, share of Grosstown acres

Not limited 0%

Somewhat limited 0%

Very limited 99%

Not rated 1%

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

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Septic tank absorption field rating across mapped Grosstown acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	98.6%
Not rated	1.4%

Drainage, water table and flooding

Share of Grosstown 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 2–28% (median 8%).
Topsoil organic matter: Median 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 Grosstown acres. Scale 0 to 100% of mapped land.

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Drainage class across mapped Grosstown 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) 81%

B: moderate infiltration 20%

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

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Hydrologic soil group across mapped Grosstown acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	80.5%
B: moderate infiltration	19.5%
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%

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 Grosstown (component kind "Series") in SSURGO: 47,407 acres.
Method: Shares are by mapped acres of Grosstown components. The profile comes from the single largest Grosstown component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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