Delaware County Soil Data
Delaware 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 Delaware County, Iowa
Alfisols and Silt Loams of Delaware
Delaware County is characterized by Alfisols, a taxonomic order known for being naturally productive for agriculture. The average pH of 6.29 is slightly acidic compared to the national 6.5 median but provides a healthy base for various crops. These well-developed soils are a hallmark of the region's glacial history.
The Ideal Silt Loam Mix
The dominant texture here is silt loam, composed of 49.0% silt, 30.9% sand, and 19.1% clay. This specific ratio offers excellent workability and enough sand to ensure the soil doesn't become too sticky or compacted. It is a highly desirable mix for both large-scale farmers and home gardeners.
Productive Soils with Solid Foundations
Delaware County boasts 3.24% organic matter, well above the 2.0% national average. While its available water capacity of 0.187 in/in is slightly below the state average of 0.195, the soil remains highly productive. A soil score of 68.7 indicates a strong agricultural foundation for the eastern part of the state.
Well Drained and Ready to Plant
Classified as 'well drained' and falling into Hydrologic Group B, this soil manages water efficiently without staying saturated. These Alfisols allow for early spring planting because they dry out faster than heavier clay soils. This makes the county particularly well-suited for high-yield row crops and healthy root systems.
Cooler Seasons in Zone 5a
In Zone 5a, Delaware County experiences shorter growing seasons, but the silt loam soil makes every day count. This soil is perfect for cool-weather crops like broccoli and kale, as well as traditional Iowa corn. Start your seeds early to take advantage of this well-drained, productive earth.
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 Delaware County have?
Delaware County's soil is classified as Silt loam. This indicates the relative proportions of sand, silt, and clay — 31% sand, 49% silt, and 19% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Delaware County's soil acidic or alkaline?
Delaware 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 Delaware County?
Delaware 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 Delaware County's soil?
Based on Delaware 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 Delaware County?
Delaware 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: Delaware County
Soil Verdict
Delaware 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
Delaware County closely matches the Iowa average hardiness conditions. The zone range of 4b-5a within the county means soil and planting decisions should account for local elevation and topography.
Planning your lawn? View lawn care data for Delaware 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.