Linn County Soil Data
Linn County, Iowa
USDA SSURGO / PHZMAvg pH
6.3
Texture
Silt loam
Drainage
Well drained
Organic Matter
3.2%
Hydrologic Group
B
Data Story
About Soil in Linn County, Iowa
Silt Loam Foundations in Linn County
Linn County features slightly acidic Alfisols with a pH of 6.31, coming in just below the national median of 6.5. This silt loam foundation represents a classic Midwestern profile built for diverse agriculture.
A Balanced Mix for Easy Management
The soil consists of 51.0% silt and 19.6% clay, providing a smooth texture that balances nutrient storage with easy workability. With 28.7% sand, these fields offer better aeration than many of their heavier clay neighbors.
Solid Organic Content for Steady Growth
Organic matter reaches 3.22%, which beats the national average of 2.0% but falls behind the Iowa state average of 3.81%. The available water capacity of 0.184 inches per inch means plants have a steady, if slightly below-average, reservoir during dry spells.
Efficient Drainage for Farming and Building
Classified as well-drained with a hydrologic group B rating, this soil moves water efficiently and resists ponding. These characteristics make the land ideal for both intensive farming and stable building foundations.
Thriving Gardens in Zone 5a
Situated in hardiness zone 5a, Linn County is perfect for cool-season vegetables like kale and hardy perennials. Start your garden today to take advantage of this reliable, high-performing silt loam.
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
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 Linn County have?
Linn County's soil is classified as Silt loam. This indicates the relative proportions of sand, silt, and clay — 29% sand, 51% silt, and 20% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Linn County's soil acidic or alkaline?
Linn 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 Linn County?
Linn 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 Linn County's soil?
Based on Linn County's Silt loam texture, pH of 6.3, 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 Linn County?
Linn 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: Linn County
Soil Verdict
Linn County is in USDA hardiness zone 5a, a cold climate zone. where winter lows can reach -20°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. With extreme winter lows, any marginally hardy plants need heavy mulch and wind protection. 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
Linn County closely matches the Iowa average hardiness conditions. The zone range of 5a-5b within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Linn County on LawnByCounty.com →
Other Counties in Iowa
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.