Adair County Soil Data
Adair County, Oklahoma
USDA SSURGO / PHZMAvg pH
4.9
Texture
Stony silt loam
Drainage
Somewhat excessively drained
Organic Matter
5.0%
Hydrologic Group
B
Data Story
About Soil in Adair County, Oklahoma
Highly Acidic Ultisols in Adair
Adair's Ultisols are highly acidic with an average pH of 4.95, far below the national median of 6.5. This stony silt loam requires careful management to balance the state average pH of 6.06.
Silty Texture with Low Sand
The soil contains 41.9% silt and 16.4% clay, creating a medium texture that balances nutrient storage. With only 24.6% sand, the ground holds moisture better than the more porous soils found in Western Oklahoma.
Exceptional Organic Matter Levels
Organic matter is impressively high at 4.98%, nearly tripling the state average of 1.72%. Despite this fertility, the water capacity of 0.140 in/in sits just below the Oklahoma norm.
Rapid Drainage for Healthy Roots
These soils are somewhat excessively drained and belong to Hydrologic Group B. This combination allows for rapid water movement, preventing the root rot common in heavier clay soils.
Thriving Gardens in Zone 7b
Adair thrives in Zone 7b, supporting blueberries and hydrangeas that love acidic environments. With such high organic matter, gardeners can start productive vegetable patches with minimal heavy fertilizing.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group B — Moderate Runoff
Moderately deep, moderately well-drained soils with moderate infiltration rates. Good balance of drainage and water retention.
Drainage Class
Somewhat excessively drained
Water is removed rapidly. Soils may be droughty and have limited water-holding capacity.
Soil Profile
Dominant texture: Stony silt loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Acidic Soil Detected
Your county's average pH is 4.9. These products help balance soil pH for healthier grass.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Adair County have?
Adair County's soil is classified as Stony silt loam. This indicates the relative proportions of sand, silt, and clay — 25% sand, 42% silt, and 16% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Adair County's soil acidic or alkaline?
Adair County's soil has a low pH of 4.9, which is strongly acidic. Acidic soils benefit from lime applications to raise pH and improve nutrient availability.
What is the drainage class for Adair County?
Adair County has a dominant drainage class of "Somewhat excessively drained." Moderate drainage allows adequate moisture retention while still permitting excess water to drain over time.
What crops or plants grow well in Adair County's soil?
Based on Adair County's Stony silt loam texture, pH of 4.9, and Somewhat excessively drained, the soil is well suited for acid-loving plants like blueberries and azaleas, row crops and vegetable gardens.
What USDA soil order is found in Adair County?
Adair County's dominant soil order is Ultisols. Ultisols are highly weathered, clay-rich soils common in humid regions. They are low in natural fertility and often require lime and fertilizer for agriculture.
Soil & Planting Advisory: Adair County
Soil Verdict
Adair County is in USDA hardiness zone 7b, a moderate climate zone. where winter lows can reach 5°F. Mild winters mean soil rarely freezes deeply, allowing year-round microbial activity and faster organic matter breakdown.
Planting Guidance
Warm-season crops, citrus relatives, and heat-loving ornamentals do well. Cool-season vegetables should be planted in fall and winter. 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
Warm soils accelerate organic matter breakdown, so compost and mulch need replenishing more frequently than in cooler zones. Sandy soils common in warm zones drain quickly; water-retentive amendments like compost or peat help hold moisture.
Regional Context
Adair County closely matches the Oklahoma average hardiness conditions. The zone range of 7a-7b within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Adair County on LawnByCounty.com →
Other Counties in Oklahoma
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.