Roberts County Soil Data
Roberts County, South Dakota
USDA SSURGO / PHZMAvg pH
7.2
Texture
Gravelly loam
Drainage
Excessively drained
Organic Matter
4.2%
Hydrologic Group
A
Data Story
About Soil in Roberts County, South Dakota
Alkaline Entisols of the Northeast
Roberts County is characterized by Entisols with a gravelly loam texture and a pH of 7.25. This makes the soil more alkaline than both the national median of 6.5 and the state average of 7.05. These soils are often young and develop quickly on the county's varied glacial terrain.
A Versatile Silt and Sand Mix
The soil composition is a blend of 42.6% silt and 34.9% sand, with a lower clay content of 22.4%. This gravelly loam texture provides enough pore space for air to reach roots while retaining necessary nutrients. It is a resilient mix that handles the transition from prairie to lakeshore well.
Elite Organic Matter Levels
Roberts County features an impressive 4.20% organic matter, far exceeding the state average of 3.75%. Combined with an available water capacity of 0.190 in/in, the soil is highly fertile and productive. This rich organic profile drives a strong soil score of 63.1.
Rapid Drainage for the Glacial Lake Region
Classified as excessively drained, these soils shed water very quickly, which is typical for gravelly loams. The county falls into Hydrologic Group A, meaning the land has a high infiltration rate and very low runoff. This makes Roberts County an excellent place for projects requiring stable, dry ground.
Thriving in the Rich Zone 4b Soil
With organic matter levels well above the state average, Roberts County gardens are primed for success in Zone 4b. The alkaline pH is particularly well-suited for asparagus, beans, and many brassicas. Focus on plants that thrive in well-drained soil to take advantage of the natural gravelly texture.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group A — Low Runoff
Sandy, well-drained soils with high infiltration rates. Water moves quickly through the soil profile. Lowest runoff potential when thoroughly wetted.
Drainage Class
Excessively drained
Water is removed very rapidly. Very sandy or gravelly soils with little water retention.
Soil Profile
Dominant texture: Gravelly loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Soil Amendment Products
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Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Roberts County have?
Roberts County's soil is classified as Gravelly loam. This indicates the relative proportions of sand, silt, and clay — 35% sand, 43% silt, and 22% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Roberts County's soil acidic or alkaline?
Roberts 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 Roberts County?
Roberts County has a dominant drainage class of "Excessively drained." Moderate drainage allows adequate moisture retention while still permitting excess water to drain over time.
What crops or plants grow well in Roberts County's soil?
Based on Roberts County's Gravelly loam texture, pH of 7.2, and Excessively drained, the soil is well suited for drought-tolerant crops and native grasses, row crops and vegetable gardens.
What USDA soil order is found in Roberts County?
Roberts 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.
Soil & Planting Advisory: Roberts County
Soil Verdict
Roberts 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
Roberts County closely matches the South Dakota average hardiness conditions.
Planning your lawn? View lawn care data for Roberts 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.