County soil summary
Soil types in Benton County, Arkansas
The most widespread soils are Clarksville, Nixa and Captina; the most common drainage class is moderately well drained (45% of the land), and typical topsoil pH is 5.3.
- Well or moderately well drained
- 95% of land · state 62%
- Typical topsoil pH
- 5.3 strongly acidic · state 5.3
- Septic fields very limited
- 94% of land · state 86%
- Subject to flooding
- 9% of land, any frequency · state 17%
Most common soils in Benton County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 82% of the mapped land; 35 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| Clarksville | 25.2% | Somewhat excessively drained | 4.5 |
| Nixa | 21.4% | Moderately well drained | 5.3 |
| Captina | 10.3% | Moderately well drained | 4.7 |
| Noark | 7.4% | Well drained | 4.8 |
| Tonti | 7.1% | Moderately well drained | 5.0 |
| Peridge | 4.0% | Well drained | 5.3 |
| Secesh | 3.8% | Well drained | 5.8 |
| Elsah | 3.2% | Somewhat excessively drained | 6.5 |
What this means
What the soils in Benton County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in Benton County is strongly acidic: pH 5.3 (most land between 4.7 and 5.8). 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 the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is very gravelly silt loam (34% of the land).
95% of the land is moderately well to excessively drained, which suits most garden plants.
For your lawn and yard
On 62% of the land, 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 94% of the land in Benton County very limited, 6% somewhat limited and 0% not limited.
Statewide, 86% of the land is very limited, so Benton County is more restrictive than typical.
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 9% of the land (8% occasional, 1% frequent).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Drainage
How long the soil stays wet
The most common drainage class is moderately well drained (45%). 95% of the land is moderately well drained or better, compared with 62% across Arkansas.
Show as a table
| Category | Benton County | Arkansas |
|---|---|---|
| Excessively drained | 24.6% | 1.0% |
| Somewhat excessively drained | 3.8% | 2.8% |
| Well drained | 21.9% | 41.3% |
| Moderately well drained | 45.1% | 16.8% |
| Somewhat poorly drained | 3.6% | 11.0% |
| Poorly drained | 0.5% | 21.8% |
| Very poorly drained | 0.0% | 0.3% |
| Not rated | 0.4% | 5.0% |
Septic absorption fields
NRCS rating for conventional drain fields
The rating looks at the soil from 24 to 60 inches deep: permeability, depth to a seasonal water table or bedrock, flooding and slope. “Very limited” means at least one feature is unfavorable enough that a conventional field is hard to make work.
Show as a table
| Category | Benton County | Arkansas |
|---|---|---|
| Not limited | 0.0% | 0.0% |
| Somewhat limited | 5.8% | 6.0% |
| Very limited | 93.5% | 86.3% |
| Not rated | 0.7% | 7.8% |
Rain, runoff and water table
Hydrologic soil group, flooding, seasonal water table
Hydrologic soil group
How fast rain soaks in when the soil is already wet. Group A soaks in fastest, D slowest.
Show as a table
| Category | Benton County | Arkansas |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 24.9% | 2.6% |
| B: moderate infiltration | 12.1% | 15.3% |
| C: slow infiltration | 23.9% | 23.1% |
| D: very slow infiltration (clayey, shallow or wet) | 27.7% | 34.4% |
| A/D: D as is, A if drained | 0.0% | 0.1% |
| B/D: D as is, B if drained | 0.0% | 2.2% |
| C/D: D as is, C if drained | 10.8% | 16.0% |
| Not rated | 0.7% | 6.4% |
Flooding
Show as a table
| Category | Benton County | Arkansas |
|---|---|---|
| No flooding | 90.7% | 73.5% |
| Rare or very rare | 0.2% | 4.1% |
| Occasional | 7.5% | 4.2% |
| Frequent or very frequent | 1.0% | 8.9% |
| Not reported | 0.5% | 9.2% |
Seasonal high water table
Show as a table
| Category | Benton County | Arkansas |
|---|---|---|
| Within 18 inches at some time of year | 10.9% | 30.2% |
| 18 inches to 3.3 feet | 38.1% | 17.8% |
| Deeper than 3.3 feet or none reported | 50.9% | 46.8% |
| Not reported | 0.2% | 5.2% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 5.3 (strongly acidic); 80% of rated land falls between 4.7 and 5.8. Median topsoil organic matter is 1.8%.
Show as a table
| Category | Benton County | Arkansas |
|---|---|---|
| Strongly acidic (below 5.5) | 81.9% | 53.7% |
| Moderately to slightly acidic (5.5–6.4) | 12.1% | 28.8% |
| Near neutral (6.5–7.3) | 5.4% | 9.2% |
| Alkaline (7.4 and up) | 0.0% | 0.6% |
| Not reported | 0.7% | 7.8% |
Texture
Show as a table
| Category | Benton County | Arkansas |
|---|---|---|
| Sandy | 0.0% | 3.3% |
| Loamy (loam, silt loam and similar) | 99.2% | 80.2% |
| Clayey (40%+ clay) | 0.2% | 8.7% |
| Organic (muck or peat) | 0.0% | 0.0% |
| Not reported (rock, urban land, etc.) | 0.7% | 7.8% |
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
- Benton County, Arkansas (FIPS 05007): 538,569 acres of mapped land, 23,780 acres of open water excluded. State comparisons pool all mapped land in Arkansas.
- Method
- Shares are by mapped land area: each map unit’s acres in the county times each soil component’s percentage. Open water is excluded. Topsoil values use the first mineral horizon of each component. Full methodology.