Soil series profile
Mt. Airy soil series
Mt. Airy is a somewhat excessively drained soil with a channery silt loam surface, mapped on 126,164 acres in 18 counties across 4 states. Hydrologic group C.
- Drainage class
- Somewhat excessively drained 78% of mapped acres
- Hydrologic group
- C 95% of mapped acres
- Typical topsoil pH
- 5.4 strongly acidic · range 5.0–5.4
- Mapped area
- 126k acres in 18 counties, 4 states
Typical Mt. Airy profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–8 in (Ap) | Channery silt loam | 5.4 | 20% | 24% | 2% |
| 8–15 in (Bw1) | Very channery silt loam | 5.0 | 23% | 22% | 0.5% |
| 15–20 in (Bw2) | Very channery silt loam | 5.0 | 23% | 22% | 0.3% |
| 20–32 in (C) | Very channery loam | 5.0 | 22% | 40% | 0.2% |
| 32–80 in (Cr) | Bedrock | Not reported | Not reported | Not reported | Not reported |
What this means
What Mt. Airy soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Mt. Airy soils is strongly acidic: pH 5.4 (most land between 5.0 and 5.4). 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 100% of mapped Mt. Airy acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is channery silt loam (56% of mapped Mt. Airy acres).
78% of mapped Mt. Airy acres is excessively or somewhat excessively drained: water moves through fast, so gardens need more frequent watering in dry spells.
For lawns and yards
On 95% 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 100% of the acres in mapped Mt. Airy soils very limited, 0% 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.
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Mt. Airy soil is found
Mapped acres
Mt. Airy is mapped in Pennsylvania, Maryland, Delaware and District of Columbia.
| County | Acres | Share of county land |
|---|---|---|
| York County, PA | 85,032 | 14.8% |
| Frederick County, MD | 27,208 | 6.4% |
| Lancaster County, PA | 3,290 | 0.5% |
| Harford County, MD | 2,449 | 0.9% |
| Chester County, PA | 2,124 | 0.4% |
| Adams County, PA | 2,024 | 0.6% |
| Baltimore County, MD | 1,463 | 0.4% |
| Howard County, MD | 813 | 0.5% |
| Carroll County, MD | 695 | 0.2% |
| Cumberland County, PA | 345 | 0.1% |
| Cecil County, MD | 215 | 0.1% |
| Bucks County, PA | 164 | 0.0% |
| Philadelphia County, PA | 151 | 0.2% |
| Montgomery County, PA | 115 | 0.0% |
| New Castle County, DE | 41 | 0.0% |
| Prince George's County, MD | 16 | 0.0% |
| District of Columbia, DC | 14 | 0.0% |
| Baltimore city, MD | 7 | 0.0% |
Septic absorption fields
NRCS rating, share of Mt. Airy acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 100.0% |
Drainage, water table and flooding
Share of Mt. Airy 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 6–30% (median 12%).
- Topsoil organic matter
- Median 2%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 78.4% |
| Well drained | 21.6% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 4.8% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 95.2% |
| 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 Mt. Airy (component kind "Series") in SSURGO: 126,164 acres.
- Method
- Shares are by mapped acres of Mt. Airy components. The profile comes from the single largest Mt. Airy component. Full methodology.