Soil series profile
Noark soil series
Noark is a well drained soil with a very gravelly silt loam surface, mapped on 637,176 acres in 48 counties across 3 states. Hydrologic group C.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- C 76% of mapped acres
- Typical topsoil pH
- 4.8 very strongly acidic · range 4.8–5.4
- Mapped area
- 637k acres in 48 counties, 3 states
Typical Noark profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–1 in (Oi) | Slightly decomposed plant material | 4.3 | Not reported | Not reported | 69% |
| 1–4 in (A) | Very gravelly silt loam | 4.8 | 10% | 22% | 4.8% |
| 4–12 in (E) | Very gravelly silt loam | 4.8 | 10% | 12% | 1.5% |
| 12–22 in (BE) | Very gravelly silty clay loam | 4.7 | 28% | 18% | 0.5% |
| 22–79 in (2Bt) | Very gravelly silty clay | 4.9 | 54% | 5% | 0.5% |
What this means
What Noark soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Noark soils is very strongly acidic: pH 4.8 (most land between 4.8 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 Noark acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is very gravelly silt loam (98% of mapped Noark acres).
100% of mapped Noark acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 76% 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 86% of the acres in mapped Noark soils very limited, 14% 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 Noark soil is found
Mapped acres
Noark is mapped in Arkansas, Missouri and Oklahoma.
| County | Acres | Share of county land |
|---|---|---|
| Searcy County, AR | 81,917 | 19.6% |
| Boone County, AR | 58,735 | 15.6% |
| Carroll County, AR | 54,580 | 13.5% |
| Stone County, AR | 52,572 | 13.6% |
| Webster County, MO | 51,302 | 13.5% |
| Benton County, AR | 39,987 | 7.4% |
| Newton County, AR | 37,263 | 7.1% |
| Izard County, AR | 36,978 | 10.0% |
| Marion County, AR | 34,883 | 9.2% |
| Madison County, AR | 27,407 | 5.1% |
| McDonald County, MO | 25,308 | 7.3% |
| Barry County, MO | 22,910 | 4.6% |
| Baxter County, AR | 18,908 | 5.4% |
| Independence County, AR | 14,566 | 3.0% |
| Stone County, MO | 13,434 | 4.5% |
| Christian County, MO | 12,357 | 3.4% |
| Ripley County, MO | 7,534 | 1.9% |
| Dent County, MO | 6,285 | 1.3% |
| Douglas County, MO | 5,879 | 1.1% |
| Newton County, MO | 4,884 | 1.2% |
| Randolph County, AR | 3,248 | 0.8% |
| Sharp County, AR | 3,198 | 0.8% |
| Washington County, AR | 2,661 | 0.4% |
| Texas County, MO | 2,365 | 0.3% |
| Butler County, MO | 1,762 | 0.4% |
| Wright County, MO | 1,730 | 0.4% |
| Laclede County, MO | 1,580 | 0.3% |
| Pulaski County, MO | 1,294 | 0.4% |
| Carter County, MO | 1,228 | 0.4% |
| Greene County, MO | 1,145 | 0.3% |
| Lawrence County, AR | 1,117 | 0.3% |
| Fulton County, AR | 927 | 0.2% |
| Ozark County, MO | 868 | 0.2% |
| Shannon County, MO | 841 | 0.1% |
| Oregon County, MO | 743 | 0.1% |
| Wayne County, MO | 734 | 0.2% |
| Benton County, MO | 730 | 0.2% |
| Howell County, MO | 674 | 0.1% |
| Cherokee County, OK | 576 | 0.1% |
| Delaware County, OK | 507 | 0.1% |
| Bollinger County, MO | 502 | 0.1% |
| Iron County, MO | 381 | 0.1% |
| Lawrence County, MO | 342 | 0.1% |
| Madison County, MO | 218 | 0.1% |
| Camden County, MO | 76 | 0.0% |
| Reynolds County, MO | 22 | 0.0% |
| Craig County, OK | 11 | 0.0% |
| Hickory County, MO | 6 | 0.0% |
Septic absorption fields
NRCS rating, share of Noark acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 13.6% |
| Very limited | 86.4% |
Drainage, water table and flooding
Share of Noark 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 5–30% (median 15%).
- Topsoil organic matter
- Median 4.8%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 100.0% |
| 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) | 0.0% |
| B: moderate infiltration | 24.4% |
| C: slow infiltration | 75.6% |
| 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 Noark (component kind "Series") in SSURGO: 637,176 acres.
- Method
- Shares are by mapped acres of Noark components. The profile comes from the single largest Noark component. Full methodology.