Soil series profile
Smithton soil series
Smithton is a poorly drained soil with a fine sandy loam surface, mapped on 487,033 acres in 37 counties across 4 states. Hydrologic group C/D.
- Drainage class
- Poorly drained 99% of mapped acres
- Hydrologic group
- C/D 80% of mapped acres
- Typical topsoil pH
- 5.0 very strongly acidic · range 5.0–5.0
- Mapped area
- 487k acres in 37 counties, 4 states
Typical Smithton profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–4 in (A) | Fine sandy loam | 5.0 | 12% | 63% | 2% |
| 4–12 in (Eg) | Fine sandy loam | 5.0 | 12% | 55% | 1.25% |
| 12–62 in (Btg1) | Loam | 5.0 | 13% | 45% | 0.75% |
| 62–80 in (Btg2) | Loam | 5.0 | 19% | 43% | 0.75% |
What this means
What Smithton soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Smithton soils is very strongly acidic: pH 5.0. 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 94% of mapped Smithton acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is fine sandy loam (74% of mapped Smithton acres).
99% of mapped Smithton acres is somewhat poorly to very poorly drained, so soil stays soggy for long spells after rain and in wet seasons. Raised beds, plants that tolerate wet feet, and not working the soil while wet all help.
For lawns and yards
On 97% 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.
A seasonal high water table comes within 18 inches of the surface on 97% of mapped acres, often in spring. Basements, sump pumps and lawns in low spots feel it first.
For a septic system
For conventional septic absorption fields, NRCS rates 94% of the acres in mapped Smithton soils very limited, 0% somewhat limited and 0% not limited (6% 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.
Flooding is mapped on 43% of the acres (22% occasional, 20% frequent).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Smithton soil is found
Mapped acres
Smithton is mapped in Arkansas, Mississippi, Alabama and Louisiana.
| County | Acres | Share of county land |
|---|---|---|
| Pearl River County, MS | 71,078 | 15.4% |
| Calhoun County, AR | 67,879 | 16.9% |
| Hancock County, MS | 41,227 | 13.6% |
| Harrison County, MS | 36,699 | 9.8% |
| Grant County, AR | 35,148 | 8.7% |
| Nevada County, AR | 25,739 | 6.5% |
| Stone County, MS | 25,722 | 9.4% |
| Ouachita County, AR | 21,216 | 4.5% |
| Union County, AR | 21,108 | 3.2% |
| Dallas County, AR | 21,090 | 5.0% |
| Mobile County, AL | 17,591 | 2.5% |
| Jackson County, MS | 17,291 | 4.2% |
| Columbia County, AR | 16,780 | 3.5% |
| Hempstead County, AR | 15,795 | 3.4% |
| Washington County, AL | 14,221 | 2.3% |
| Hot Spring County, AR | 6,072 | 1.5% |
| Lafayette County, AR | 5,601 | 1.7% |
| Little River County, AR | 5,271 | 1.6% |
| Sevier County, AR | 5,032 | 1.4% |
| Union Parish, LA | 4,570 | 0.8% |
| Clark County, AR | 3,976 | 0.7% |
| Pike County, AR | 1,425 | 0.4% |
| Jefferson Davis County, MS | 1,331 | 0.6% |
| Cleveland County, AR | 1,265 | 0.3% |
| Monroe County, AL | 1,138 | 0.2% |
| Autauga County, AL | 420 | 0.1% |
| Miller County, AR | 420 | 0.1% |
| George County, MS | 376 | 0.1% |
| Winn Parish, LA | 367 | 0.1% |
| Perry County, MS | 234 | 0.1% |
| Howard County, AR | 214 | 0.1% |
| Lauderdale County, MS | 201 | 0.1% |
| Forrest County, MS | 184 | 0.1% |
| Claiborne Parish, LA | 148 | 0.0% |
| Greene County, MS | 96 | 0.0% |
| Jones County, MS | 95 | 0.0% |
| Winston County, MS | 12 | 0.0% |
Septic absorption fields
NRCS rating, share of Smithton acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 94.4% |
| Not rated | 5.6% |
Drainage, water table and flooding
Share of Smithton acres
- Depth to seasonal high water table
- About 6 inches (median where reported); within 18 inches on 97% of acres.
- Flooding
- Mapped as flooding on 43% of acres (22% occasional, 20% frequent).
- Slope
- Typically 1–1% (median 1%).
- 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 | 0.0% |
| Moderately well drained | 0.3% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 98.8% |
| Very poorly drained | 0.0% |
| Not rated | 0.9% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 0.0% |
| D: very slow infiltration (clayey, shallow or wet) | 3.0% |
| A/D: D as is, A if drained | 0.0% |
| B/D: D as is, B if drained | 13.4% |
| C/D: D as is, C if drained | 80.4% |
| Not rated | 3.2% |
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 Smithton (component kind "Series") in SSURGO: 487,033 acres.
- Method
- Shares are by mapped acres of Smithton components. The profile comes from the single largest Smithton component. Full methodology.