Custer and Pennington Counties Area, Prairie Parts, South Dakota

Survey Area SD606• South Dakota

The dominant drainage class is Well drained and the dominant hydrologic group is D (very slow infiltration, high runoff). 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 Custer and Pennington Counties Area, Prairie Parts, South Dakota. 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
Samsil clay, 15 to 40 percent slopes	122K	Well drained	D	Very limited	Very limited
Pierre-Samsil, moderately deep clays, 6 to 25 percent slopes	83K	Well drained	D	Very limited	Very limited
Nunn loam, 2 to 6 percent slopes	67K	Well drained	C	Somewhat limited	Very limited
Pierre clay, 6 to 20 percent slopes	60K	Well drained	D	Very limited	Very limited
Nunn loam, 0 to 2 percent slopes	55K	Well drained	C	Somewhat limited	Very limited
Zigweid-Nihill complex, 6 to 15 percent slopes	40K	Well drained	B	Somewhat limited	Somewhat limited
Satanta loam, 0 to 2 percent slopes	39K	Well drained	B	Not limited	Somewhat limited
Fairburn clay loam, 9 to 40 percent slopes	37K	Well drained	D	Very limited	Very limited
Norrest silty clay loam, 6 to 15 percent slopes	33K	Well drained	C	Very limited	Very limited
Lohmiller silty clay, channeled, 0 to 3 percent slopes, occasionally flooded	32K	Well drained	C	Very limited	Very limited
Midway silty clay loam, 9 to 35 percent slopes	31K	Well drained	D	Very limited	Very limited
Razor-Midway complex, 6 to 15 percent slopes	31K	Well drained	D	Very limited	Very limited
Satanta loam, 2 to 6 percent slopes	30K	Well drained	B	Not limited	Somewhat limited
Fairburn-Orella-Badland complex, 15 to 45 percent slopes	26K	Well drained	D	Very limited	Very limited
Kyle clay, 2 to 6 percent slopes	25K	Well drained	D	Very limited	Very limited
Samsil-Rock outcrop complex, 10 to 50 percent slopes	23K	Well drained	D	Very limited	Very limited
Badland	22K	Excessively drained	D	Very limited	Very limited
Whitewater-Orella clays, 3 to 9 percent slopes	20K	Well drained	D	Very limited	Very limited
Ottumwa clay, 2 to 6 percent slopes	19K	Well drained	C	Very limited	Very limited
Pierre clay, 2 to 6 percent slopes	19K	Well drained	D	Very limited	Very 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.

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.

Inceptisols

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

Vertisols

High-clay soils that shrink and swell dramatically. Fertile but challenging for foundations and septic systems.

Alfisols

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

What This Means

Building & Foundations

About 71% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, flood-prone areas. A geotechnical assessment is recommended before building.

Septic Systems

About 86% 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.