Alexander County, Illinois

Survey Area IL003• Illinois

The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). The most common soil order is Alfisols — moderately leached forest soils with a clay-enriched subsoil. 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 Alexander 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
Water	13K			Not rated	Not rated
Stookey-Clarksville complex, 18 to 35 percent slopes	11K	Well drained	B	Very limited	Very limited
Darwin silty clay, 0 to 2 percent slopes, occasionally flooded	6K	Poorly drained	D	Very limited	Very limited
Stookey silt loam, 25 to 35 percent slopes	6K	Well drained	B	Very limited	Very limited
Bonnie silt loam, 0 to 2 percent slopes, occasionally flooded	6K	Poorly drained	C/D	Very limited	Very limited
Armiesburg-Sarpy complex, 0 to 2 percent slopes, frequently flooded, long duration	5K	Well drained	B	Very limited	Very limited
Darwin silty clay, 0 to 2 percent slopes, frequently flooded, long duration	4K	Very poorly drained	D	Very limited	Very limited
Elsah silt loam, 1 to 4 percent slopes, occasionally flooded	4K	Well drained	B	Very limited	Very limited
Karnak clay, 0 to 2 percent slopes, occasionally flooded	4K	Poorly drained	C/D	Very limited	Very limited
Riley silty clay loam, 0 to 2 percent slopes, frequently flooded, long duration	4K	Somewhat poorly drained	B/D	Very limited	Very limited
Karnak silty clay, 0 to 2 percent slopes, frequently flooded, long duration	3K	Very poorly drained	C/D	Very limited	Very limited
Ware loam, 1 to 6 percent slopes, frequently flooded, long duration	3K	Well drained	B	Very limited	Very limited
Clarksville-Stookey complex, 35 to 70 percent slopes	3K	Somewhat excessively drained	B	Very limited	Very limited
Haymond silt loam, 0 to 3 percent slopes, occasionally flooded	3K	Well drained	B	Very limited	Very limited
Karnak and Cape silty clays, undrained, 0 to 2 percent slopes, frequently flooded	3K	Very poorly drained	C/D	Very limited	Very limited
Drury silt loam, 10 to 18 percent slopes	3K	Well drained	B	Somewhat limited	Somewhat limited
Cairo silty clay, 0 to 2 percent slopes, occasionally flooded	3K	Poorly drained	D	Very limited	Very limited
Wakeland silt loam, 0 to 2 percent slopes, occasionally flooded	3K	Somewhat poorly drained	B/D	Very limited	Very limited
Darwin and Jacob silty clays, undrained, 0 to 2 percent slopes, frequently flooded	3K	Very poorly drained	D	Very limited	Very limited
Menfro silt loam, 10 to 18 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.

Alfisols

Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.

Inceptisols

Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.

Mollisols

Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.

Entisols

Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.

Ultisols

Strongly weathered clay soils of the Southeast. Acidic and naturally low in nutrients. Clay subsoil can slow drainage.

What This Means

Building & Foundations

About 79% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.

Septic Systems

About 79% 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

Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.