HomeSoil seriesTama
Tama soil series
Tama soils cover 1,189,059 mapped acres, mostly in Iowa, Wisconsin and Minnesota. USDA rates shrink-swell a limit for houses without basements on 43% of that land, and a shallow water table a limit for basements on 0%.
It is the leading soil series by area in 8 of the counties and cities on this site, including Marshall County, IA; Grundy County, IA; Scott County, IA.
SSURGO survey versions to August 5, 2026 · series description revised 2015-03
of its land: shrink-swell limits houses without basements
of its land: a shallow water table limits basements
median highest linear extensibility (6% and up is high)
median highest clay content in the top 150 cm
USDA's description
The Tama series consists of very deep, well drained soils formed in loess. These soils are on interfluves and side slopes on uplands and on treads and risers on stream terraces in river valleys. Slope ranges from 0 to 20 percent. Mean annual air temperature is about 9 degrees C (48 degrees F). Mean annual precipitation is about 909 millimeters (36 inches).
Source: USDA NRCS series description (OSD) for Tama, revised 2015-03. Read it.
Engineering properties
| Mapped area (SSURGO) | 1,189,059 acres |
| Shrink-swell limits houses without basements | 42.7% |
| Shallow water table limits basements | 0.0% |
| Very limited for septic absorption fields | 96.4% |
| Most common drainage class | Well drained |
| Most common hydrologic soil group | C |
| Taxonomic class | Fine-silty, mixed, superactive, mesic Typic Argiudolls |
| Type location | Major Land Resource Area (MLRA) 104-Eastern Iowa and Minnesota Till Prairies, Tama County, Iowa subset |
Where Tama is mapped
| State | Mapped acres |
|---|---|
| Iowa | 873,076 |
| Wisconsin | 142,212 |
| Minnesota | 123,890 |
| Illinois | 49,268 |
| Indiana | 613 |
Places where Tama leads
Counties and cities where Tama covers more mapped land than any other series.
| Place | Share of mapped land |
|---|---|
| Marshall County, IA | 36% |
| Grundy County, IA | 28% |
| Scott County, IA | 27% |
| Cedar County, IA | 23% |
| Tama County, IA | 21% |
| Jasper County, IA | 17% |
| Poweshiek County, IA | 16% |
| Muscatine County, IA | 10% |
Other places where Tama is a main soil
Counties and cities where Tama is among the six soil series covering the most mapped land, but not the first. Share of the place's mapped land.
Counties
Sources
Shares and properties: USDA NRCS SSURGO via Soil Data Access, weighted by each component's share of its map units. Description: the USDA NRCS series description. How we count.