Clay County Soil Data
Clay County, Illinois
USDA SSURGO / PHZMAvg pH
6.3
Texture
Silt Loam
Drainage
N/A
Organic Matter
2.0%
Hydrologic Group
N/A
Data Story
About Soil in Clay County, Illinois
The Slightly Acidic Ground of Clay County
Clay County soils have an average pH of 6.26, making them more acidic than the state average of 6.39 and the national median of 6.5. This acidity is common in Southern Illinois and can influence which nutrients are available to plants. While taxonomic data is sparse, this profile often requires occasional lime applications for optimal crop yields.
High Silt Content with Low Sand
Despite its name, the soil here is actually 64.4% silt and only 21.5% clay, with a low sand content of 14.1%. This silty-dominant texture means the soil can feel very fine and smooth but may be prone to erosion if left uncovered. The low sand percentage suggests the soil stays cool and moist for longer periods during the spring.
Challenging Organic Matter Thresholds
Organic matter is at 2.00%, which is the national average but significantly lower than the Illinois state average of 2.94%. Interestingly, the available water capacity is quite high at 0.211 in/in, exceeding the state average of 0.204 in/in. This means while the soil is lean on nutrients, it is excellent at holding onto every drop of rain it receives.
High Capacity for Water Storage
Specific drainage and hydrologic data are unavailable, but the high water capacity of 0.211 in/in indicates a soil that retains moisture effectively. With a high silt percentage, the ground may stay saturated longer than in sandier regions, which is a key consideration for site drainage. Managing runoff is important here to protect the fine silty topsoil.
Extended Growing in Zone 6b
Clay County sits in Zone 6b, offering a warm environment where sweet potatoes and peppers love to grow. Because organic matter is lower at 2.00%, your garden will benefit greatly from mulching and natural soil amendments. With its high water-holding capacity, your plants will be well-protected against short-term summer droughts.
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 Clay County have?
Clay County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 14% sand, 64% silt, and 22% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Clay County's soil acidic or alkaline?
Clay County's soil has a pH of 6.3, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Clay County?
Drainage class data is not currently available for Clay County.
What crops or plants grow well in Clay County's soil?
Based on Clay County's Silt Loam texture, pH of 6.3, 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 Clay County?
The dominant USDA soil order for Clay County is not currently available in our dataset.
Soil & Planting Advisory: Clay County
Soil Verdict
Clay County is in USDA hardiness zone 6b, a moderate climate zone. where winter lows can reach -5°F. Freeze-thaw cycles are moderate; soil biology slows in winter but recovers reliably in spring, supporting a broad range of plants.
Planting Guidance
A wide plant palette is possible: deciduous trees, most shrubs, cool-season vegetables, and many perennials thrive here. 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
Moderate freeze-thaw cycles naturally aerate the soil but can also cause compaction in clay-heavy areas; annual core aeration is beneficial. Organic matter amendments decompose at a moderate pace — aim for 3-5% organic content for optimal fertility. When soil temperatures drop below freezing, microbial nitrogen cycling stops; spring fertilization is more effective than late-fall application.
Regional Context
Clay County closely matches the Illinois average hardiness conditions.
Planning your lawn? View lawn care data for Clay 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.