Dewey County Soil Data
Dewey County, South Dakota
USDA SSURGO / PHZMAvg pH
7.2
Texture
Clay Loam
Drainage
N/A
Organic Matter
2.6%
Hydrologic Group
N/A
Data Story
About Soil in Dewey County, South Dakota
Alkaline Soils on the Plains
Dewey County's average pH of 7.18 is higher than the national median of 6.5 and the state average of 7.05. This alkalinity suggests a landscape rich in calcium and other minerals common to the western plains. Specific taxonomic classification data for these soils is currently unavailable.
Higher Clay Content for Retention
The soil is comprised of 30.3% clay, which is higher than many neighboring counties. Combined with 39.7% silt and 28.7% sand, this mix creates a heavier texture that can be challenging to work when wet. However, this high clay percentage is excellent for locking in minerals.
Challenging Water and Organic Levels
Organic matter sits at 2.62%, which exceeds the national average but falls well below the state average of 3.75%. The available water capacity of 0.157 in/in is also lower than the state average of 0.182 in/in. These factors contribute to the county's lower soil score of 47.8.
Understanding Local Water Movement
Drainage classification data is limited for this region, but the 30.3% clay content suggests slower water movement. Heavy rains may lead to surface runoff rather than quick infiltration. Land managers should focus on practices that improve soil structure and reduce erosion.
Resilient Gardening in Zone 4b
Dewey County gardens must be tough to handle Zone 4b winters and lower water capacity. Focus on drought-tolerant native plants and use mulch to preserve what moisture the soil can hold. Despite the lower soil score, hardy shrubs and grasses can thrive with proper care.
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: Clay Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Clay Soil Detected
Clay soils can struggle with drainage. These products improve soil structure and water flow.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Dewey County have?
Dewey County's soil is classified as Clay Loam. This indicates the relative proportions of sand, silt, and clay — 29% sand, 40% silt, and 30% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Dewey County's soil acidic or alkaline?
Dewey 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 Dewey County?
Drainage class data is not currently available for Dewey County.
What crops or plants grow well in Dewey County's soil?
Based on Dewey County's Clay Loam texture, pH of 7.2, and drainage class, the soil is well suited for drought-tolerant crops and native grasses, row crops and vegetable gardens.
What USDA soil order is found in Dewey County?
The dominant USDA soil order for Dewey County is not currently available in our dataset.
Soil & Planting Advisory: Dewey County
Soil Verdict
Dewey County is in USDA hardiness zone 4b, a cold climate zone. where winter lows can reach -25°F. Soils here experience deep freeze cycles that can disrupt structure, kill shallow roots, and slow microbial activity for months each year.
Planting Guidance
Focus on cold-hardy perennials, native grasses, and conifers. The short growing window favors plants with low heat requirements. With extreme winter lows, any marginally hardy plants need heavy mulch and wind protection. 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
Deep winter freezing can create soil heaving that pushes shallow-rooted plants out of the ground; add 3-4 inches of organic mulch each fall. Soil drainage is critical — frozen, waterlogged soil kills roots faster than cold alone. When soil temperatures drop below freezing, microbial nitrogen cycling stops; spring fertilization is more effective than late-fall application.
Regional Context
Dewey County closely matches the South Dakota average hardiness conditions.
Planning your lawn? View lawn care data for Dewey 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.