Polk County Soil Data
Polk County, Missouri
USDA SSURGO / PHZMAvg pH
5.9
Texture
Silt Loam
Drainage
Subaqueous
Organic Matter
3.0%
Hydrologic Group
N/A
Data Story
About Soil in Polk County, Missouri
Mildly Acidic Grounds in Polk
Polk County soils show an average pH of 5.89, placing them slightly below the state average of 6.09 and the national median of 6.5. This mildly acidic profile is common across the region's diverse landscape and may require lime for certain sensitive crops. It is otherwise very productive for native species.
Silty Mix with Easy Workability
The soil mix is 63.9% silt and 16.4% clay, offering a good balance between nutrient storage and physical workability. The 18.6% sand content helps prevent the soil from becoming too compacted under heavy machinery or foot traffic. This blend is ideal for diverse agricultural uses.
Healthy Organic Matter and Hydration
Organic matter levels reach 2.95%, which is nearly a full point higher than the national 2.0% average. The soil’s available water capacity of 0.189 in/in also edges out the state average of 0.183 in/in. This ensures a healthy environment for root development and consistent moisture levels.
Understanding Saturated Soil Drainage
Polk displays subaqueous drainage characteristics, suggesting the land may retain moisture in low-lying areas or wetlands. Without detailed hydrologic group data, careful observation of ponding after rain is recommended. Planning for drainage-sensitive plants requires attention to the local topography.
Gardening Success in Zone 6b
Sitting in zone 6b, the county’s superior water capacity supports healthy perennials and productive vegetable gardens. It is a great time to start a garden that thrives on this reliable moisture profile. Native Missouri plants will feel right at home in this silty ground.
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
Subaqueous
Drainage class: Subaqueous
Soil Profile
Dominant texture: Silt Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Acidic Soil Detected
Your county's average pH is 5.9. These products help balance soil pH for healthier grass.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Polk County have?
Polk County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 19% sand, 64% silt, and 16% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Polk County's soil acidic or alkaline?
Polk County's soil has a pH of 5.9, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Polk County?
Polk County has a dominant drainage class of "Subaqueous." Moderate drainage allows adequate moisture retention while still permitting excess water to drain over time.
What crops or plants grow well in Polk County's soil?
Based on Polk County's Silt Loam texture, pH of 5.9, and Subaqueous, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens.
What USDA soil order is found in Polk County?
The dominant USDA soil order for Polk County is not currently available in our dataset.
Soil & Planting Advisory: Polk County
Soil Verdict
Polk County is in USDA hardiness zone 6b, a moderate climate zone. where winter lows can reach -5°F. Freeze-thaw cycles are moderate; soil biology slows in winter but recovers reliably in spring, supporting a broad range of plants.
Planting Guidance
A wide plant palette is possible: deciduous trees, most shrubs, cool-season vegetables, and many perennials thrive here. Winter protection (mulch, burlap wraps) helps push the zone boundary for desired species. 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
Moderate freeze-thaw cycles naturally aerate the soil but can also cause compaction in clay-heavy areas; annual core aeration is beneficial. Organic matter amendments decompose at a moderate pace — aim for 3-5% organic content for optimal fertility. When soil temperatures drop below freezing, microbial nitrogen cycling stops; spring fertilization is more effective than late-fall application.
Regional Context
Polk County closely matches the Missouri average hardiness conditions.
Planning your lawn? View lawn care data for Polk County on LawnByCounty.com →
Other Counties in Missouri
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.