Soil series profile
Carnasaw soil series
Carnasaw is a well drained soil with a gravelly silt loam surface, mapped on 1,773,351 acres in 17 counties across 2 states. Hydrologic group C.
- Drainage class
- Well drained >99% of mapped acres
- Hydrologic group
- C >99% of mapped acres
- Typical topsoil pH
- 5.3 strongly acidic · range 5.3–5.3
- Mapped area
- 1.8M acres in 17 counties, 2 states
Typical Carnasaw profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–3 in (A) | Gravelly silt loam | 5.3 | 21% | 26% | 1.25% |
| 3–6 in (Bt1) | Silty clay loam | 5.0 | 39% | 18% | 0.25% |
| 6–40 in (Bt2) | Clay | 5.0 | 53% | 18% | 0.25% |
| 40–72 in (Cr) | Bedrock | Not reported | Not reported | Not reported | Not reported |
What this means
What Carnasaw soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Carnasaw soils is strongly acidic: pH 5.3. 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 Carnasaw acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is stony loam (33% of mapped Carnasaw acres).
>99% of mapped Carnasaw acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On >99% 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 >99% of the acres in mapped Carnasaw 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 Carnasaw soil is found
Mapped acres
Carnasaw is mapped in Oklahoma and Arkansas.
| County | Acres | Share of county land |
|---|---|---|
| Le Flore County, OK | 222,909 | 22.0% |
| McCurtain County, OK | 198,538 | 16.8% |
| Scott County, AR | 192,237 | 33.6% |
| Pushmataha County, OK | 168,996 | 18.9% |
| Latimer County, OK | 142,394 | 30.7% |
| Saline County, AR | 135,940 | 29.6% |
| Perry County, AR | 124,484 | 35.4% |
| Atoka County, OK | 117,906 | 19.0% |
| Yell County, AR | 112,833 | 19.0% |
| Garland County, AR | 102,393 | 23.6% |
| Pulaski County, AR | 71,144 | 14.5% |
| Haskell County, OK | 41,548 | 11.3% |
| Montgomery County, AR | 39,322 | 7.9% |
| Polk County, AR | 31,533 | 5.8% |
| Hot Spring County, AR | 30,487 | 7.7% |
| Clark County, AR | 21,323 | 3.8% |
| Pike County, AR | 19,363 | 5.0% |
Septic absorption fields
NRCS rating, share of Carnasaw acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 99.8% |
| Not rated | 0.2% |
Drainage, water table and flooding
Share of Carnasaw acres
- Depth to seasonal high water table
- About 3.1 feet (37 in) (median where reported).
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 8–30% (median 18%).
- Topsoil organic matter
- Median 1.2%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 99.8% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 0.2% |
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 | 99.8% |
| 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 | 0.2% |
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 Carnasaw (component kind "Series") in SSURGO: 1,773,351 acres.
- Method
- Shares are by mapped acres of Carnasaw components. The profile comes from the single largest Carnasaw component. Full methodology.