Harrison County, Iowa
The most common soil here is Monona, on about 26% of the land: a silt loam, smooth, like flour. Napier and Ida come next.
About 71% of the land drains well, and 21% stays wet for long stretches; groundwater comes within two feet of the surface under 21% of it.
USDA rates 55% of the land very limited for a standard septic drain field, and 56% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 27% 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 Harrison 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 B (moderate infiltration). The most common soil order is Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter. 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 Harrison 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 |
|---|---|---|---|---|---|
| Ida silt loam, 14 to 20 percent slopes, severely eroded | 39K | Well drained | B | Very limited | Very limited |
| Napier silt loam, 5 to 9 percent slopes | 36K | Well drained | B | Not limited | Somewhat limited |
| Napier silt loam, 2 to 5 percent slopes | 33K | Well drained | B | Not limited | Somewhat limited |
| Monona silt loam, 9 to 14 percent slopes, eroded | 25K | Well drained | B | Somewhat limited | Somewhat limited |
| Monona silt loam, 5 to 9 percent slopes, eroded | 20K | Well drained | B | Not limited | Somewhat limited |
| Monona silt loam, 2 to 5 percent slopes | 18K | Well drained | B | Not limited | Somewhat limited |
| Ida silt loam, 9 to 14 percent slopes, severely eroded | 18K | Well drained | B | Somewhat limited | Somewhat limited |
| Luton silty clay, thin surface | 16K | Poorly drained | D | Very limited | Very limited |
| Albaton silty clay, 0 to 2 percent slopes, occasionally flooded | 16K | Poorly drained | D | Very limited | Very limited |
| Monona silt loam, 5 to 9 percent slopes | 15K | Well drained | B | Not limited | Somewhat limited |
| Ida silt loam, 20 to 30 percent slopes, severely eroded | 13K | Well drained | B | Very limited | Very limited |
| McPaul silt loam | 13K | Well drained | B | Very limited | Very limited |
| Luton silty clay | 11K | Poorly drained | D | Very limited | Very limited |
| Dockery-Quiver silt loams, deep loess, 0 to 2 percent slopes, occasionally flooded | 10K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Monona silt loam, 14 to 20 percent slopes, eroded | 10K | Well drained | B | Very limited | Very limited |
| Haynie silt loam, 0 to 2 percent slopes, occasionally flooded | 10K | Moderately well drained | B | Very limited | Very limited |
| Kennebec silt loam, 0 to 2 percent slopes, occasionally flooded, overwash | 9K | Moderately well drained | B | Very limited | Very limited |
| Kennebec silt loam, 0 to 2 percent slopes, occasionally flooded | 9K | Moderately well drained | B | Very limited | Very limited |
| Napier silt loam, 9 to 14 percent slopes | 7K | Well drained | B | Somewhat limited | Somewhat limited |
| Hamburg silt loam, 40 to 75 percent slopes | 6K | Somewhat excessively drained | B | Very 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 56% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 55% 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.