Soil series profile
Tama soil series
Tama is a well drained soil with a silty clay loam surface, mapped on 826,772 acres in 54 counties across 5 states. Hydrologic group C.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- C 94% of mapped acres
- Typical topsoil pH
- 6.5 slightly acidic · range 6.2–6.5
- Mapped area
- 827k acres in 54 counties, 5 states
Typical Tama profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–6 in (Ap) | Silty clay loam | 6.5 | 27% | 3% | 3.5% |
| 6–10 in (A1) | Silty clay loam | 6.0 | 28% | 3% | 3% |
| 10–14 in (A2) | Silty clay loam | 5.9 | 28% | 3% | 3% |
| 14–18 in (BA) | Silty clay loam | 5.9 | 31% | 3% | 1.5% |
| 18–32 in (Bt1) | Silty clay loam | 5.9 | 33% | 3% | 1% |
| 32–45 in (Bt2) | Silty clay loam | 5.9 | 31% | 3% | 1% |
| 45–60 in (BC) | Silty clay loam | 6.1 | 28% | 3% | 0.3% |
What this means
What Tama soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Tama soils is slightly acidic: pH 6.5 (most land between 6.2 and 6.5), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Tama acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silty clay loam (56% of mapped Tama acres).
100% of mapped Tama acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 94% 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 96% of the acres in mapped Tama soils very limited, 4% 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 Tama soil is found
Mapped acres
Tama is mapped in Iowa, Minnesota, Wisconsin, Illinois and Indiana.
| County | Acres | Share of county land |
|---|---|---|
| Grundy County, IA | 82,768 | 25.8% |
| Marshall County, IA | 73,338 | 20.1% |
| Tama County, IA | 64,045 | 14.0% |
| Cedar County, IA | 63,612 | 17.2% |
| Lafayette County, WI | 44,961 | 11.1% |
| Scott County, IA | 44,143 | 15.1% |
| Fillmore County, MN | 42,254 | 7.7% |
| Clinton County, IA | 34,908 | 7.9% |
| Jasper County, IA | 34,494 | 7.4% |
| Grant County, WI | 33,080 | 4.5% |
| Benton County, IA | 31,140 | 6.8% |
| Poweshiek County, IA | 28,073 | 7.5% |
| Johnson County, IA | 21,690 | 5.6% |
| Olmsted County, MN | 21,633 | 5.2% |
| Logan County, IL | 19,474 | 5.0% |
| Winona County, MN | 18,697 | 4.7% |
| Iowa County, WI | 15,058 | 3.1% |
| Muscatine County, IA | 13,716 | 4.9% |
| Hardin County, IA | 13,234 | 3.6% |
| Linn County, IA | 10,050 | 2.2% |
| Wabasha County, MN | 9,976 | 3.0% |
| Dubuque County, IA | 9,901 | 2.5% |
| Mason County, IL | 9,039 | 2.7% |
| Houston County, MN | 8,808 | 2.5% |
| Jones County, IA | 8,039 | 2.2% |
| Iowa County, IA | 6,364 | 1.7% |
| Tazewell County, IL | 6,324 | 1.6% |
| Winneshiek County, IA | 5,901 | 1.3% |
| Delaware County, IA | 5,628 | 1.5% |
| Jackson County, IA | 5,314 | 1.3% |
| Mitchell County, IA | 5,144 | 1.7% |
| Warren County, IA | 3,723 | 1.0% |
| Dodge County, MN | 3,466 | 1.2% |
| Polk County, IA | 3,161 | 0.9% |
| Allamakee County, IA | 3,136 | 0.8% |
| Louisa County, IA | 2,846 | 1.1% |
| Green County, WI | 2,778 | 0.7% |
| Goodhue County, MN | 2,675 | 0.6% |
| Clayton County, IA | 2,529 | 0.5% |
| Sauk County, WI | 1,993 | 0.4% |
| Morgan County, IL | 1,693 | 0.5% |
| Butler County, IA | 1,488 | 0.4% |
| Sangamon County, IL | 1,371 | 0.2% |
| Marion County, IA | 1,336 | 0.4% |
| Franklin County, IA | 789 | 0.2% |
| Vermillion County, IN | 613 | 0.4% |
| Howard County, IA | 605 | 0.2% |
| Macon County, IL | 594 | 0.2% |
| Fayette County, IA | 476 | 0.1% |
| Dane County, WI | 322 | 0.0% |
| Buffalo County, WI | 197 | 0.0% |
| De Witt County, IL | 166 | 0.1% |
| Crawford County, WI | 10 | 0.0% |
| Vernon County, WI | 0 | 0.0% |
Septic absorption fields
NRCS rating, share of Tama acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 4.0% |
| Very limited | 96.0% |
Drainage, water table and flooding
Share of Tama acres
- Depth to seasonal high water table
- About 4.8 feet (57 in) (median where reported).
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 4–7% (median 4%).
- Topsoil organic matter
- Median 3.5%.
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 | 6.5% |
| C: slow infiltration | 93.5% |
| 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 Tama (component kind "Series") in SSURGO: 826,772 acres.
- Method
- Shares are by mapped acres of Tama components. The profile comes from the single largest Tama component. Full methodology.