Plymouth County Soil Data
Plymouth County, Iowa
USDA SSURGO / PHZMAvg pH
6.9
Texture
Silt Loam
Drainage
N/A
Organic Matter
3.0%
Hydrologic Group
N/A
Data Story
About Soil in Plymouth County, Iowa
Alkaline Soils on the Western Edge
Plymouth County soils average a pH of 6.89, which is significantly more alkaline than the national median of 6.5. This chemical profile favors specific crops that prefer less acidic environments.
Silt Dominance and High Stability
Silt makes up a massive 62.2% of the soil, with sand accounting for only 12.5%. This composition creates a smooth, flour-like texture that is highly productive but prone to erosion if left uncovered.
Superior Water Holding Capacity
The available water capacity is 0.213 in/in, outperforming the state average of 0.195 in/in. Although organic matter is 3.02%, lower than the state average, the soil score remains high at 73.6.
Managing High Silt Levels
While specific drainage classes aren't recorded, the high silt levels mean this soil stores water effectively. Proper drainage tile is often a key consideration for managing these moisture-heavy fields.
Hardy Crops for Zone 5a
Zone 5a gardeners can successfully grow pumpkins, squash, and hardy grains in this silty earth. It is time to plant your spring seeds and see what this western Iowa soil can do!
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 Plymouth County have?
Plymouth County's soil is classified as Silt Loam. This indicates the relative proportions of sand, silt, and clay — 13% sand, 62% silt, and 25% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Plymouth County's soil acidic or alkaline?
Plymouth County's soil has a pH of 6.9, which is near neutral. This range is ideal for most garden plants and field crops.
What is the drainage class for Plymouth County?
Drainage class data is not currently available for Plymouth County.
What crops or plants grow well in Plymouth County's soil?
Based on Plymouth County's Silt Loam texture, pH of 6.9, 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 Plymouth County?
The dominant USDA soil order for Plymouth County is not currently available in our dataset.
Soil & Planting Advisory: Plymouth County
Soil Verdict
Plymouth 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
Plymouth County closely matches the Iowa average hardiness conditions.
Planning your lawn? View lawn care data for Plymouth 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.