Union County Soil Data
Union County, South Dakota
Avg pH
7.2
Texture
Silty clay
Drainage
Poorly drained
Organic Matter
3.0%
Hydrologic Group
D
Data Story
About Soil in Union County, South Dakota
Young Soils of the Entisol Order
Union County features a pH of 7.18 and belongs to the Entisols taxonomic order, representing relatively young soil. The county score of 56.3 reflects its unique geographic position near major river valleys.
Rich Silty Clay Deposits
The soil is characterized as silty clay, containing 51.3% silt and 29.9% clay. This dense mix provides excellent mineral richness but can be heavy to work with when the ground is wet.
Reliable State-Average Performance
Organic matter levels stand at 2.96%, exceeding the 2.0% national average. The available water capacity of 0.180 in/in is nearly identical to the state average, providing dependable moisture for crops.
Slow Drainage Considerations
This area is classified as poorly drained and belongs to hydrologic group D. Water moves slowly through the soil, which is a critical consideration for both farming and basement construction.
Vibrant Growth in 5a
Hardiness Zone 5a allows for a long and productive growing season. Focus on moisture-loving plants or use raised beds to manage the naturally poor drainage of these silty clay soils.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group D — High Runoff
Clay soils with very slow infiltration rates. Highest runoff potential. These soils have a permanent high water table or are shallow over impervious material.
Drainage Class
Poorly drained
Water is removed so slowly that the soil is wet at or near the surface much of the year. Drainage improvement usually needed.
Soil Profile
Dominant texture: Silty clay
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Frequently Asked Questions
What type of soil does Union County have?
Union County's soil is classified as Silty clay. This indicates the relative proportions of sand, silt, and clay — 19% sand, 51% silt, and 30% clay. Clay soils retain water and nutrients but can have drainage challenges.
Is Union County's soil acidic or alkaline?
Union County's soil has a pH of 7.2, which is near neutral. This range is ideal for most garden plants and field crops.
What is the drainage class for Union County?
Union County has a dominant drainage class of "Poorly drained." Poorly drained soils retain water for extended periods, which can limit crop choices and may require tile drainage or raised beds.
What crops or plants grow well in Union County's soil?
Based on Union County's Silty clay texture, pH of 7.2, and Poorly drained, the soil is well suited for drought-tolerant crops and native grasses, row crops and vegetable gardens, rice, cranberries, and other water-tolerant species.
What USDA soil order is found in Union County?
Union County's dominant soil order is Entisols. Entisols are recently formed soils with little to no horizon development. They are common on floodplains, steep slopes, and sandy deposits.
Planning your lawn? View lawn care data for Union County on LawnByCounty.com →
Other Counties in South Dakota
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.