Boone County, Illinois
The most common soil here is Drummer, on about 8% of the land: a silty clay loam, smooth and slightly sticky. Pecatonica and Flagg come next.
About 46% of the land drains well, and 44% stays wet for long stretches; groundwater comes within two feet of the surface under 42% of it.
USDA rates 74% of the land very limited for a standard septic drain field, and 45% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 5% 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 Boone County, Illinois, 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/D (varies with drainage). 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 Boone County, Illinois. 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 |
|---|---|---|---|---|---|
| Drummer silty clay loam, 0 to 2 percent slopes | 15K | Poorly drained | B/D | Very limited | Very limited |
| Sable silty clay loam, 0 to 2 percent slopes | 8K | Poorly drained | B/D | Very limited | Very limited |
| Flagg silt loam, 2 to 5 percent slopes | 8K | Well drained | B | Somewhat limited | Somewhat limited |
| Pecatonica silt loam, 2 to 5 percent slopes | 8K | Well drained | B | Somewhat limited | Somewhat limited |
| Kendall silt loam, 0 to 2 percent slopes | 8K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Parr silt loam, 2 to 5 percent slopes | 7K | Moderately well drained | C | Somewhat limited | Very limited |
| Waupecan silt loam, 0 to 2 percent slopes | 5K | Well drained | B | Not limited | Very limited |
| Pecatonica silt loam, 5 to 10 percent slopes, eroded | 5K | Well drained | B | Somewhat limited | Somewhat limited |
| St. Charles silt loam, 2 to 5 percent slopes | 4K | Well drained | B | Somewhat limited | Somewhat limited |
| Odell silt loam, 0 to 2 percent slopes | 4K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Elburn silt loam, cool, 0 to 2 percent slopes | 4K | Somewhat poorly drained | C | Very limited | Very limited |
| Dakota loam, 0 to 2 percent slopes | 4K | Well drained | B | Not limited | Very limited |
| Selma loam, 0 to 2 percent slopes | 4K | Poorly drained | B/D | Very limited | Very limited |
| Comfrey loam, 0 to 2 percent slopes, frequently flooded | 3K | Poorly drained | B/D | Very limited | Very limited |
| Virgil silt loam, 0 to 2 percent slopes | 3K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Stronghurst silt loam, 0 to 2 percent slopes | 3K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Selmass loam, 0 to 2 percent slopes | 3K | Poorly drained | B/D | Very limited | Very limited |
| Lisbon silt loam, 0 to 2 percent slopes | 3K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Atterberry silt loam, 0 to 2 percent slopes | 3K | Somewhat poorly drained | B/D | Very limited | Very limited |
| St. Charles silt loam, 0 to 2 percent slopes | 3K | Well drained | B | Somewhat limited | Somewhat 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 45% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 74% 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.