Soil series profile
Joplin soil series
Joplin is a well drained soil with a loam surface, mapped on 772,671 acres in 16 counties across 2 states. Hydrologic group C.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- C 100% of mapped acres
- Typical topsoil pH
- 7.1 neutral · range 7.1–7.1
- Mapped area
- 773k acres in 16 counties, 2 states
Typical Joplin profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–6 in (Ap) | Loam | 7.1 | 24% | 39% | 2% |
| 6–9 in (Bt) | Clay loam | 7.3 | 32% | 35% | 1.5% |
| 9–22 in (Bk1) | Clay loam | 8.2 | 28% | 34% | 1% |
| 22–41 in (Bk2) | Clay loam | 8.4 | 28% | 34% | 0.75% |
| 41–57 in (BCyz) | Loam | 8.2 | 26% | 38% | 0.5% |
| 57–79 in (Cz) | Loam | 8.1 | 26% | 38% | 0.5% |
What this means
What Joplin soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Joplin soils is neutral: pH 7.1, the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Joplin acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (>99% of mapped Joplin acres).
100% of mapped Joplin acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 100% 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 100% of the acres in mapped Joplin 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 Joplin soil is found
Mapped acres
Joplin is mapped in Montana and Wyoming.
| County | Acres | Share of county land |
|---|---|---|
| Hill County, MT | 235,915 | 12.8% |
| Liberty County, MT | 122,463 | 13.5% |
| Chouteau County, MT | 121,437 | 4.8% |
| Toole County, MT | 118,349 | 11.0% |
| Phillips County, MT | 65,010 | 1.7% |
| Valley County, MT | 35,307 | 1.1% |
| Blaine County, MT | 35,098 | 1.3% |
| McCone County, MT | 12,526 | 0.7% |
| Pondera County, MT | 12,287 | 1.2% |
| Roosevelt County, MT | 9,707 | 0.6% |
| Glacier County, MT | 2,386 | 0.2% |
| Teton County, MT | 1,140 | 0.1% |
| Dawson County, MT | 559 | 0.0% |
| Garfield County, MT | 195 | 0.0% |
| Park County, WY | 172 | 0.0% |
| Wibaux County, MT | 119 | 0.0% |
Septic absorption fields
NRCS rating, share of Joplin acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 100.0% |
Drainage, water table and flooding
Share of Joplin 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 2–8% (median 5%).
- 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 | 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 | 0.0% |
| C: slow infiltration | 100.0% |
| 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% |
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 Joplin (component kind "Series") in SSURGO: 772,671 acres.
- Method
- Shares are by mapped acres of Joplin components. The profile comes from the single largest Joplin component. Full methodology.