Franklin County Soil Data
Franklin County, Illinois
USDA SSURGO / PHZMAvg pH
6.1
Texture
Silt Loam
Drainage
N/A
Organic Matter
1.7%
Hydrologic Group
N/A
Data Story
About Soil in Franklin County, Illinois
Lower pH Levels in Franklin
Franklin County's soil is more acidic than its neighbors, with a pH of 6.09 compared to the national median of 6.5. This acidity level is also notably lower than the Illinois state average of 6.39.
Fine-Textured Silt and Clay Mix
The soil is dominated by 69.4% silt, with a 22.2% clay component and very little sand at 8.4%. This fine-textured mix feels floury when dry and can become slippery when wet during the spring thaw.
Reliable Water Storage Despite Lower OM
Organic matter measures 1.68%, falling below both the national 2.0% average and the state 2.94% average. Despite lower organic levels, the available water capacity of 0.209 in/in remains slightly above the state benchmark of 0.204.
Strategies for Slow-Draining Soil
While local drainage class records are sparse, the high silt and clay levels often lead to slow natural drainage. Strategic garden placement is important to avoid waterlogged roots in this dense soil profile.
Warm Seasons in Zone 7a
As part of the warmer Zone 7a, Franklin County offers a longer growing season for heat-loving plants. Focus on soil amendments to boost organic matter and support a thriving vegetable patch.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Hydrologic group data not available.
Drainage Class
Drainage class data not available.
Soil Profile
Dominant texture: Silt Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Soil Amendment Products
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Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Franklin County have?
Franklin County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 8% sand, 69% silt, and 22% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Franklin County's soil acidic or alkaline?
Franklin County's soil has a pH of 6.1, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Franklin County?
Drainage class data is not currently available for Franklin County.
What crops or plants grow well in Franklin County's soil?
Based on Franklin County's Silt Loam texture, pH of 6.1, and drainage class, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens.
What USDA soil order is found in Franklin County?
The dominant USDA soil order for Franklin County is not currently available in our dataset.
Soil & Planting Advisory: Franklin County
Soil Verdict
Franklin County is in USDA hardiness zone 7a, a moderate climate zone. where winter lows can reach 0°F. Mild winters mean soil rarely freezes deeply, allowing year-round microbial activity and faster organic matter breakdown.
Planting Guidance
Warm-season crops, citrus relatives, and heat-loving ornamentals do well. Cool-season vegetables should be planted in fall and winter. Winter protection (mulch, burlap wraps) helps push the zone boundary for desired species. Always match plant selections to the specific microclimate of your property — low spots, slopes, and wind exposure can shift effective hardiness by half a zone.
Soil Implications
Warm soils accelerate organic matter breakdown, so compost and mulch need replenishing more frequently than in cooler zones. Sandy soils common in warm zones drain quickly; water-retentive amendments like compost or peat help hold moisture. When soil temperatures drop below freezing, microbial nitrogen cycling stops; spring fertilization is more effective than late-fall application.
Regional Context
Franklin County is somewhat warmer than the Illinois statewide average. The zone range of 6b-7a within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Franklin County on LawnByCounty.com →
Other Counties in Illinois
Soil data sourced from USDA SSURGO via Soil Data Access. Data is informational only and should not be used as a substitute for on-site soil testing. Contact your local NRCS office for site-specific soil information.