Soil series profile
Armour soil series
Armour is a well drained soil with a silt loam surface, mapped on 188,094 acres in 41 counties across 3 states. Hydrologic group B.
- Drainage class
- Well drained >99% of mapped acres
- Hydrologic group
- B >99% of mapped acres
- Typical topsoil pH
- 5.6 moderately acidic · range 5.6–5.6
- Mapped area
- 188k acres in 41 counties, 3 states
Typical Armour profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–14 in (H1) | Silt loam | 5.6 | 24% | 7% | 2.25% |
| 14–40 in (H2) | Silty clay loam | 5.6 | 30% | 7% | 0.25% |
| 40–60 in (H3) | Silty clay loam | 5.6 | 38% | 9% | 0.25% |
What this means
What Armour soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Armour soils is moderately acidic: pH 5.6. Many vegetables grow well here, and some gardens benefit from a little lime. Test before adding any.
Loamy topsoil (loam, silt loam and similar) covers >99% of mapped Armour acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (98% of mapped Armour acres).
>99% of mapped Armour 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 78% of the acres in mapped Armour soils very limited, 21% 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 Armour soil is found
Mapped acres
Armour is mapped in Tennessee, Alabama and Kentucky.
| County | Acres | Share of county land |
|---|---|---|
| Maury County, TN | 27,216 | 7.0% |
| Williamson County, TN | 26,278 | 7.1% |
| Giles County, TN | 16,980 | 4.4% |
| Dickson County, TN | 14,679 | 4.7% |
| Davidson County, TN | 13,020 | 4.1% |
| Lincoln County, TN | 12,761 | 3.5% |
| Smith County, TN | 12,169 | 6.0% |
| Marshall County, TN | 9,608 | 4.0% |
| Wilson County, TN | 7,631 | 2.1% |
| Hickman County, TN | 5,718 | 1.5% |
| Wayne County, TN | 5,104 | 1.1% |
| Rutherford County, TN | 3,730 | 0.9% |
| Sumner County, TN | 3,550 | 1.1% |
| DeKalb County, TN | 3,189 | 1.6% |
| Macon County, TN | 2,630 | 1.3% |
| Cheatham County, TN | 2,273 | 1.2% |
| Jackson County, TN | 2,136 | 1.1% |
| Trousdale County, TN | 2,128 | 2.9% |
| Stewart County, TN | 2,056 | 0.7% |
| Bedford County, TN | 1,892 | 0.6% |
| Perry County, TN | 1,772 | 0.7% |
| Clay County, TN | 1,672 | 1.1% |
| Humphreys County, TN | 1,662 | 0.5% |
| Lauderdale County, AL | 1,147 | 0.3% |
| Moore County, TN | 1,096 | 1.3% |
| Coffee County, TN | 1,087 | 0.4% |
| Putnam County, TN | 965 | 0.4% |
| Cannon County, TN | 943 | 0.6% |
| Benton County, TN | 840 | 0.3% |
| Montgomery County, TN | 826 | 0.2% |
| Calloway County, KY | 547 | 0.2% |
| Lewis County, TN | 271 | 0.2% |
| Marshall County, KY | 154 | 0.1% |
| Decatur County, TN | 102 | 0.0% |
| Warren County, TN | 93 | 0.0% |
| Robertson County, TN | 49 | 0.0% |
| Houston County, TN | 48 | 0.0% |
| Franklin County, TN | 43 | 0.0% |
| Overton County, TN | 15 | 0.0% |
| Henry County, TN | 12 | 0.0% |
| White County, TN | 2 | 0.0% |
Septic absorption fields
NRCS rating, share of Armour acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 21.3% |
| Very limited | 78.2% |
| Not rated | 0.5% |
Drainage, water table and flooding
Share of Armour acres
- Depth to seasonal high water table
- None reported within about 6.5 feet (median where reported).
- Flooding
- Mapped as flooding on 4% of acres (4% occasional, 0% frequent).
- Slope
- Typically 3–9% (median 4%).
- Topsoil organic matter
- Median 2%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| 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% |
| Not rated | 0.5% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 99.5% |
| 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 | 0.5% |
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 Armour (component kind "Series") in SSURGO: 188,094 acres.
- Method
- Shares are by mapped acres of Armour components. The profile comes from the single largest Armour component. Full methodology.