Union County Soil Data
Union County, Arkansas
USDA SSURGO / PHZMAvg pH
5.1
Texture
Sandy Loam
Drainage
N/A
Organic Matter
1.7%
Hydrologic Group
D
Data Story
About Soil in Union County, Arkansas
Strongly Acidic Soils of South Arkansas
Union County presents a very acidic profile with an average pH of 5.10, significantly lower than the state average of 5.56. This low pH presents challenges for most crops without regular lime applications to neutralize the acidity.
Sand-Dominant Composition Influences Drainage
The soil is over half sand at 55.4%, paired with 31.9% silt and 12.7% clay. This high sand content results in a coarse texture that provides plenty of pore space but struggles to retain nutrients over time.
Lower Organic Levels and Water Storage
Organic matter sits at 1.68%, falling short of the state’s 4.15% benchmark. Coupled with an available water capacity of 0.134 in/in, this soil requires careful irrigation and frequent organic amendments to support healthy plant growth.
High Runoff Risk Despite Sandy Texture
The soil is classified in hydrologic group D, indicating very low infiltration rates when saturated. Although sandy, the underlying layers often restrict water movement, leading to increased surface runoff during heavy Southern rainstorms.
Southern Hardiness in Zone 8b
Union County's warm 8b zone allows for a long growing season of heat-tolerant plants like citrus in pots or southern peas. Success in this acidic, sandy soil depends on proactive soil testing and regular fertilization.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group D — High Runoff
Clay soils with very slow infiltration rates. Highest runoff potential. These soils have a permanent high water table or are shallow over impervious material.
Drainage Class
Drainage class data not available.
Soil Profile
Dominant texture: Sandy Loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Acidic Soil Detected
Your county's average pH is 5.1. These products help balance soil pH for healthier grass.
Browse Soil AmendmentsFrequently Asked Questions
What type of soil does Union County have?
Union County's soil is classified as Sandy Loam. This indicates the relative proportions of sand, silt, and clay — 55% sand, 32% silt, and 13% 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 low pH of 5.1, which is strongly acidic. Acidic soils benefit from lime applications to raise pH and improve nutrient availability.
What is the drainage class for Union County?
Drainage class data is not currently available for Union County.
What crops or plants grow well in Union County's soil?
Based on Union County's Sandy Loam texture, pH of 5.1, and drainage class, 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 Union County?
The dominant USDA soil order for Union County is not currently available in our dataset.
Soil & Planting Advisory: Union County
Soil Verdict
Union County is in USDA hardiness zone 8b, a warm climate zone. where winter lows can reach 15°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
Union County closely matches the Arkansas average hardiness conditions. The zone range of 8a-8b within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Union County on LawnByCounty.com →
Other Counties in Arkansas
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.