Mills County Soil Data
Mills County, Iowa
Avg pH
6.8
Texture
Silty clay loam
Drainage
Poorly drained
Organic Matter
3.0%
Hydrologic Group
D
Data Story
About Soil in Mills County, Iowa
Mollisols Define the Mills County Landscape
Mills County features a dominant texture of silty clay loam belonging to the Mollisol taxonomic order. At 6.78, the average pH sits slightly above the national median of 6.5 and the Iowa state average of 6.43. This slightly alkaline profile provides a stable foundation for the region's productive agricultural land.
High Silt Levels Drive Soil Workability
The soil contains a high 61.4% silt content paired with 27.5% clay and 11.0% sand. This heavy silt concentration ensures excellent nutrient retention but requires careful management to prevent compaction. While the clay content aids in structure, it can make the ground heavy to work when wet.
Superior Water Storage Despite Lower Organic Matter
Organic matter levels average 3.00%, which falls below the state average of 3.81% but stays well above the national 2.0% benchmark. Notably, the available water capacity of 0.205 in/in exceeds the state average of 0.195 in/in. This means the soil is exceptionally good at holding onto moisture during dry spells.
Managing Poor Drainage and Group D Soils
The county's soil is primarily classified as poorly drained and falls into hydrologic group D. These characteristics mean water moves slowly through the profile, often requiring tiles for farming or specialized foundations for building. Gardeners should consider raised beds to avoid waterlogged roots in these heavy soils.
Thriving in Hardiness Zone 5b
Mills County sits in USDA Hardiness Zone 5b, where native prairie grasses and deep-rooted vegetables flourish in the silty loam. Fruit trees like apples and pears perform well when provided with proper site drainage. Start your garden today to take advantage of some of the best moisture-retaining soil in the state.
Soil Composition
Soil pH
Soil Series
Detailed soil series data not yet available for this county.
Hydrologic Group
Group D — High Runoff
Clay soils with very slow infiltration rates. Highest runoff potential. These soils have a permanent high water table or are shallow over impervious material.
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: Silty clay loam
Typical soil profile. Actual depths vary by location.
USDA Soil Orders
Frequently Asked Questions
What type of soil does Mills County have?
Mills County's soil is classified as Silty clay loam. This indicates the relative proportions of sand, silt, and clay — 11% sand, 61% silt, and 28% clay. Loamy soils hold moisture well and support a wide range of plants.
Is Mills County's soil acidic or alkaline?
Mills County's soil has a pH of 6.8, which is near neutral. This range is ideal for most garden plants and field crops.
What is the drainage class for Mills County?
Mills 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 Mills County's soil?
Based on Mills County's Silty clay loam texture, pH of 6.8, 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 Mills County?
Mills 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.
Planning your lawn? View lawn care data for Mills 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.