Rock County, Minnesota
The most common soil here is Moody, on about 12% of the land: a silty clay loam, smooth and slightly sticky. Trent and Splitrock come next.
About 51% of the land drains well, and 28% stays wet for long stretches; groundwater comes within two feet of the surface under 28% of it.
USDA rates 93% of the land very limited for a standard septic drain field, and 50% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 13% of the land floods occasionally or more, and bedrock lies within 40 inches under 5% of it.
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 Rock County, Minnesota, 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 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 Rock County, Minnesota. 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 |
|---|---|---|---|---|---|
| Trent silty clay loam, 0 to 3 percent slopes | 37K | Well drained | C | Somewhat limited | Very limited |
| Moody silty clay loam, cool, 2 to 6 percent slopes | 35K | Well drained | C | Somewhat limited | Very limited |
| Splitrock silty clay loam, 2 to 5 percent slopes | 32K | Moderately well drained | C | Very limited | Very limited |
| Whitewood silty clay loam, 0 to 2 percent slopes | 24K | Poorly drained | C | Very limited | Very limited |
| Marcus silty clay loam, 0 to 2 percent slopes | 17K | Poorly drained | C/D | Very limited | Very limited |
| Sac silty clay loam, loam substratum, 2 to 5 percent slopes | 14K | Moderately well drained | C | Somewhat limited | Very limited |
| Graceville silty clay loam, 0 to 2 percent slopes | 11K | Well drained | C | Somewhat limited | Very limited |
| Primghar silty clay loam, 1 to 3 percent slopes | 10K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Galva silty clay loam, 2 to 5 percent slopes | 9K | Well drained | B | Not limited | Somewhat limited |
| Spillco silt loam, 0 to 2 percent slopes, occasionally flooded | 8K | Moderately well drained | C | Very limited | Very limited |
| Nora silt loam, 4 to 10 percent slopes, eroded | 8K | Well drained | B | Not limited | Somewhat limited |
| Spillco silt loam, 0 to 3 percent slopes, frequently flooded | 7K | Moderately well drained | C | Very limited | Very limited |
| Flandreau silt loam, 2 to 6 percent slopes | 6K | Well drained | B | Not limited | Very limited |
| Calco silty clay loam, 0 to 2 percent slopes, frequently flooded | 5K | Poorly drained | C/D | Very limited | Very limited |
| Calco silty clay loam, 0 to 2 percent slopes, occasionally flooded | 4K | Poorly drained | B/D | Very limited | Very limited |
| Havelock clay loam, 0 to 2 percent slopes, frequently flooded | 4K | Poorly drained | B/D | Very limited | Very limited |
| Ihlen silty clay loam, 2 to 6 percent slopes | 4K | Well drained | C | Very limited | Very limited |
| Everly silty clay loam, 2 to 6 percent slopes | 4K | Well drained | C | Somewhat limited | Very limited |
| Alcester silty clay loam, cool, 0 to 2 percent slopes | 4K | Well drained | C | Somewhat limited | Very limited |
| Ihlen-Rock outcrop complex, 0 to 4 percent slopes | 4K | Well drained | C | 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 50% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 93% 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
Drainage is generally favorable for gardening. Adding compost and mulch will improve fertility and water retention. Test your soil's pH before planting — most vegetables prefer 6.0-7.0.