Union County Soil Data
Union County, Ohio
USDA SSURGO / PHZMAvg pH
6.4
Texture
Silt loam
Drainage
Well drained
Organic Matter
3.5%
Hydrologic Group
C
Data Story
About Soil in Union County, Ohio
Union's Prime Soil Identity
Union County features highly productive Alfisols with a pH of 6.41, nearly matching the 6.5 national median. This makes Union's soil some of the most chemically balanced in Ohio, far exceeding the state average of 5.97.
Strong Silt Loam Mix
The soil is a silt loam consisting of 53.0% silt and 23.9% clay. This higher clay content gives the soil more body and excellent nutrient-holding capacity compared to sandier neighboring counties.
Exceptional Water Retention
Union boasts a massive available water capacity of 0.207 in/in, one of the highest in the state. Even with a moderate 3.49% organic matter, the soil's structure ensures plants remain resilient during periods of low rainfall.
Reliable Well-Drained Soils
Classified as well-drained, these soils manage water effectively despite being in Hydrologic Group C. The combination suggests that while the surface drains well, the soil stores significant moisture deep in the profile for later use.
Top-Tier Growing in 6a
Union's soil score of 80.8 is impressively high, making it a dream for any gardener in Hardiness Zone 6a. Whether you are growing prize-winning tomatoes or a simple flower bed, these soils provide the perfect start.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group C — Moderate-High Runoff
Soils with slow infiltration rates, often with a layer that impedes downward water movement. Higher clay content restricts drainage.
Drainage Class
Well drained
Water is removed from the soil readily but not rapidly. Optimal for most plants and construction.
Soil Profile
Dominant texture: Silt 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 Union County have?
Union County's soil is classified as Silt loam. This indicates the relative proportions of sand, silt, and clay — 22% sand, 53% silt, and 24% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Union County's soil acidic or alkaline?
Union County's soil has a pH of 6.4, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Union County?
Union County has a dominant drainage class of "Well drained." Well-drained soils allow excess water to move through quickly, reducing waterlogging risk and supporting most field and garden crops.
What crops or plants grow well in Union County's soil?
Based on Union County's Silt loam texture, pH of 6.4, and Well drained, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens, most annual and perennial crops.
What USDA soil order is found in Union County?
Union County's dominant soil order is Alfisols. Alfisols are moderate to high base-status soils with a clay-enriched subsoil. They support productive forests and cropland across temperate regions.
Soil & Planting Advisory: Union County
Soil Verdict
Union County is in USDA hardiness zone 6a, a moderate climate zone. where winter lows can reach -10°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
Union County closely matches the Ohio average hardiness conditions.
Planning your lawn? View lawn care data for Union County on LawnByCounty.com →
Other Counties in Ohio
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.