Washington County Soil Data
Washington County, Illinois
USDA SSURGO / PHZMAvg pH
6.3
Texture
Silt Loam
Drainage
N/A
Organic Matter
2.0%
Hydrologic Group
N/A
Data Story
About Soil in Washington County, Illinois
Classic Southern Illinois Soil Profile
Washington County has an average pH of 6.32, which is slightly more acidic than the state average of 6.39 and the national median of 6.5. This pH level is typical for the region and generally hospitable to most agriculture. While local taxonomy is not specified, the acidity is well within the manageable range.
Heavy Silt for Deep Moisture
This soil is comprised of 70.7% silt, 21.0% clay, and 8.3% sand. The high silt percentage gives the ground a heavy, moisture-rich character that can feel dense underfoot. Because there is very little sand to break up the particles, the soil requires careful handling to maintain its structure.
Exceptional Water Storage Capacity
With an available water capacity of 0.215 in/in, this soil outperforms the state average of 0.204 in/in. Organic matter is 1.98%, which is lower than the Illinois average of 2.94% but nearly matches the national average. Adding organic amendments like compost will help unlock the soil's full potential.
Hydraulic Powerhouse of the Prairie
Official drainage classes are not recorded, but the high silt content and high water capacity define its hydrology. The soil acts like a sponge, soaking up rainfall and holding it deep in the profile for plant use. This is a major benefit during the hotter, dryer months of the southern Illinois summer.
Sun-Loving Crops for Zone 6b
Washington County's Zone 6b climate allows for a long growing season and early spring planting. The soil's ability to hold onto water makes it excellent for thirsty crops like melons and tomatoes. Start your garden journey here and enjoy the benefits of this moisture-retentive earth.
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
Drainage class data not available.
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 Washington County have?
Washington County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 8% sand, 71% silt, and 21% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Washington County's soil acidic or alkaline?
Washington County's soil has a pH of 6.3, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Washington County?
Drainage class data is not currently available for Washington County.
What crops or plants grow well in Washington County's soil?
Based on Washington County's Silt Loam texture, pH of 6.3, and drainage class, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens.
What USDA soil order is found in Washington County?
The dominant USDA soil order for Washington County is not currently available in our dataset.
Soil & Planting Advisory: Washington County
Soil Verdict
Washington 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
Washington County closely matches the Illinois average hardiness conditions.
Planning your lawn? View lawn care data for Washington County on LawnByCounty.com →
Other Counties in Illinois
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.