Marshall County, Iowa
The most common soil here is Tama, on about 36% of the land: a silty clay loam, smooth and slightly sticky. Killduff and Colo come next.
About 56% of the land drains well, and 29% stays wet for long stretches; groundwater comes within two feet of the surface under 29% of it.
USDA rates 94% of the land very limited for a standard septic drain field, and 37% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 10% of the land floods occasionally or more.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Marshall County, Iowa, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). The most common soil order is Inceptisols — young soils with minimal horizon development but more than Entisols. 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. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| 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 |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 37% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 94% 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.