Marion County Soil Data
Marion County, Iowa
Avg pH
6.2
Texture
Silt loam
Drainage
Poorly drained
Organic Matter
3.1%
Hydrologic Group
C/D
Data Story
About Soil in Marion County, Iowa
Acidic Silt Loams in Marion County
Marion County is dominated by Alfisols with a pH of 6.19, which is notably more acidic than the national median of 6.5. This silt loam profile is a staple of the region, though it may need lime to boost performance for certain crops.
Fine Texture and Nutrient Storage
The soil consists of 56.7% silt and 25.5% clay, making it very fine-textured and excellent for nutrient storage. Because it only contains 16.7% sand, it can be prone to compaction and may feel slick when wet.
Competitive Water Capacity
At 3.06%, the organic matter is lower than the Iowa state average but still significantly better than the national average. The available water capacity of 0.194 inches per inch is nearly identical to the state average of 0.195.
Navigating Poor Drainage and Saturation
Rated as poorly drained with a hydrologic group C/D, this soil struggles to move water and often remains saturated. These conditions are challenging for basements but excellent for moisture-loving plants and wetland restoration.
Powerhouse Soil for Diverse Crops
Hardiness zone 5b allows for a diverse garden of squashes, beans, and orchard fruits. Despite the heavy drainage, this moisture-retentive soil is a powerhouse if you manage the water levels correctly.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group C — Moderate-High Runoff
Soils with slow infiltration rates, often with a layer that impedes downward water movement. Higher clay content restricts drainage.
Drainage Class
Poorly drained
Water is removed so slowly that the soil is wet at or near the surface much of the year. Drainage improvement usually needed.
Soil Profile
Dominant texture: Silt loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Frequently Asked Questions
What type of soil does Marion County have?
Marion County's soil is classified as Silt loam. This indicates the relative proportions of sand, silt, and clay — 17% sand, 57% silt, and 25% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Marion County's soil acidic or alkaline?
Marion County's soil has a pH of 6.2, which is moderately acidic. This range suits many crops and is common across much of the eastern US.
What is the drainage class for Marion County?
Marion County has a dominant drainage class of "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 Marion County's soil?
Based on Marion County's Silt loam texture, pH of 6.2, and 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 Marion County?
Marion 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.
Planning your lawn? View lawn care data for Marion 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.