Marshall County Soil Data
Marshall County, Illinois
USDA SSURGO / PHZMAvg pH
6.6
Texture
Silt loam
Drainage
Somewhat poorly drained
Organic Matter
2.7%
Hydrologic Group
B/D
Data Story
About Soil in Marshall County, Illinois
Classic Illinois Mollisols
Marshall County is characterized by Mollisols, the dark and fertile prairie soils that define the Midwest. With an average pH of 6.58, the soil is slightly more alkaline than the state average but remains ideal for high-yield farming.
Perfect Silt Loam Texture
The dominant texture is silt loam, consisting of 60.5% silt and 22.6% clay. This balanced composition offers excellent workability while the 16.9% sand content ensures some natural grit and structure.
High Soil Score and Stability
The county earns a high soil score of 77.1, bolstered by 2.66% organic matter. While this is slightly below the state average of 2.94%, it far exceeds the national average of 2.0%, signaling deep natural fertility.
Managing Poorly Drained Prairies
The soil is classified as somewhat poorly drained and falls into hydrologic group B/D. This means while the soil is naturally rich, it may require tiling or careful water management to prevent root rot in wet years.
Diverse Options in Zone 5b
Residing in Zone 5b, Marshall County is perfect for corn, soybeans, and hearty cool-weather crops like brassicas. Start your garden today to take advantage of some of the state's most iconic agricultural land.
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 poorly drained
Water is removed slowly enough that the soil is wet at shallow depths for significant periods. Mottling present.
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 Marshall County have?
Marshall County's soil is classified as Silt loam. This indicates the relative proportions of sand, silt, and clay — 17% sand, 60% silt, and 23% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Marshall County's soil acidic or alkaline?
Marshall County's soil has a pH of 6.6, which is near neutral. This range is ideal for most garden plants and field crops.
What is the drainage class for Marshall County?
Marshall County has a dominant drainage class of "Somewhat poorly drained." Poorly drained soils retain water for extended periods, which can limit crop choices and may require tile drainage or raised beds.
What crops or plants grow well in Marshall County's soil?
Based on Marshall County's Silt loam texture, pH of 6.6, and Somewhat poorly drained, the soil is well suited for vegetables, grains, and most field crops, row crops and vegetable gardens, rice, cranberries, and other water-tolerant species.
What USDA soil order is found in Marshall County?
Marshall County's dominant soil order is Mollisols. Mollisols are fertile, dark-colored soils that formed under grassland vegetation. They are among the most productive agricultural soils in the world.
Soil & Planting Advisory: Marshall County
Soil Verdict
Marshall County is in USDA hardiness zone 5b, a cold climate zone. where winter lows can reach -15°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
Marshall County is somewhat cooler than the Illinois statewide average.
Planning your lawn? View lawn care data for Marshall 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.