Alexander County Soil Data
Alexander County, Illinois
USDA SSURGO / PHZMAvg pH
6.2
Texture
Silt Loam
Drainage
N/A
Organic Matter
1.9%
Hydrologic Group
N/A
Data Story
About Soil in Alexander County, Illinois
Southern Illinois Acidic Ground
Alexander County soils lean more acidic than their northern neighbors with an average pH of 6.22, notably lower than the 6.5 national median. This level of acidity can limit the availability of certain nutrients without proper soil amendments. The overall soil score of 63.4 reflects these unique chemical challenges in the state's southern tip.
A Silty Mix with Gritty Potential
The soil profile consists of 60.9% silt and 22.1% clay, balanced by 17.0% sand. This sand content is higher than many other Illinois counties, which can slightly improve the workability of the earth. However, the silt still dominates the texture, requiring attention to avoid surface crusting after heavy rains.
Lean Organic Matter and Water Storage
Alexander County reports 1.94% organic matter, which falls just below the national 2.0% average and significantly trails the 2.94% Illinois average. The available water capacity of 0.198 in/in is also slightly lower than the state benchmark. This means growers must work harder to build soil health and manage irrigation during summer heat.
Hydrology in the River Lowlands
While official drainage classifications are not provided, the combination of lower organic matter and 0.198 AWC points to a soil that may dry out faster than typical Illinois ground. The soil score of 63.4 suggests that managing water flow is a primary concern for local land managers. Proper cover cropping can help improve both water retention and soil structure over time.
Warmer Seasons in Zone 7a
As a rare Illinois representative of zone 7a, Alexander County enjoys a long, warm growing season. This climate is ideal for heat-loving crops like sweet potatoes, melons, and even southern specialty plants. The local soil provides a unique opportunity to experiment with varieties that wouldn't survive further north.
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
Browse products to improve your soil health and lawn performance.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Alexander County have?
Alexander County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 17% sand, 61% silt, and 22% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Alexander County's soil acidic or alkaline?
Alexander County's soil has a pH of 6.2, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Alexander County?
Drainage class data is not currently available for Alexander County.
What crops or plants grow well in Alexander County's soil?
Based on Alexander County's Silt Loam texture, pH of 6.2, 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 Alexander County?
The dominant USDA soil order for Alexander County is not currently available in our dataset.
Soil & Planting Advisory: Alexander County
Soil Verdict
Alexander 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
Alexander County is somewhat warmer than the Illinois statewide average.
Planning your lawn? View lawn care data for Alexander 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.