Marshall County, Iowa
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Marshall County, Iowa.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Tama silty clay loam, 2 to 5 percent slopes | 48K | Well drained | C | Somewhat limited | Very limited |
| Tama silty clay loam, 5 to 9 percent slopes, eroded | 39K | Well drained | C | Somewhat limited | Very limited |
| Colo-Ely complex, 0 to 5 percent slopes | 23K | Poorly drained | C/D | Very limited | Very limited |
| Tama silty clay loam, 5 to 9 percent slopes | 23K | Well drained | C | Somewhat limited | Very limited |
| Tama silty clay loam, 9 to 14 percent slopes, eroded | 23K | Well drained | C | Somewhat limited | Very limited |
| Muscatine silty clay loam, 0 to 2 percent slopes | 22K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Killduff silty clay loam, 9 to 14 percent slopes, eroded | 21K | Moderately well drained | C | Somewhat limited | Very limited |
| Killduff silty clay loam, 5 to 9 percent slopes, eroded | 11K | Moderately well drained | C | Somewhat limited | Very limited |
| Shelby loam, 14 to 18 percent slopes, moderately eroded | 7K | Well drained | C | Very limited | Very limited |
| Garwin silty clay loam, 0 to 2 percent slopes | 6K | Poorly drained | C/D | Very limited | Very limited |
| Ackmore-Colo complex, 2 to 5 percent slopes | 6K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Ackmore silt loam, 0 to 2 percent slopes, occasionally flooded | 5K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Colo silty clay loam, 0 to 2 percent slopes, occasionally flooded | 5K | Poorly drained | C/D | Very limited | Very limited |
| Zook silty clay loam, 0 to 2 percent slopes, occasionally flooded | 4K | Poorly drained | D | Very limited | Very limited |
| Downs silt loam, till plain, 9 to 14 percent slopes, eroded | 4K | Well drained | C | Somewhat limited | Very limited |
| Clarion loam, Bemis moraine, 6 to 10 percent slopes, moderately eroded | 4K | Well drained | B | Somewhat limited | Somewhat limited |
| Colo-Hanlon-Lawson complex, channeled, 0 to 2 percent slopes | 4K | Poorly drained | C/D | Very limited | Very limited |
| Clarion loam, Bemis moraine, 2 to 6 percent slopes | 4K | Well drained | B | Somewhat limited | Somewhat limited |
| Shelby loam, 9 to 14 percent slopes, moderately eroded | 4K | Well drained | C | Somewhat limited | Very limited |
| Tama silty clay loam, 0 to 2 percent slopes | 3K | Well drained | C | Somewhat limited | Very limited |
What This Means
Building & Foundations
About 30% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 97% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.