Geospatial Laboratory for Soil Informatics
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Soil Resources of Iowa

Probe truck parked in a field among large wind turbines on a clear day.

This page offers a comprehensive visual and data-driven guide to Iowa’s soil landscape, organized into thematic sections to support soil education, land management, and geospatial interpretation.

Physiography

Color-coded map of Iowa showing major landform regions, including drift plains, uplands, and lowlands.
Map highlighting Iowa’s distinct landform regions with color separation for easy visualization.
Color-coded map of Iowa showing principal soil associations and major soil areas.
Geospatial map outlining Iowa’s major soil regions and principal soil associations.
Chart listing Iowa soil regions with abbreviations, major soil area numbers, names, and parent material descriptions.
Reference table detailing Iowa’s 22 principal soil associations, including soil names, parent materials, and major soil area numbers.

Climate

Color-coded map of Iowa showing average annual precipitation from 1981 to 2010, with higher values in the southeast and lower in the northwest.
Map of Iowa illustrating the 30-year average annual precipitation (in inches) from 1981 to 2010, with regional rainfall gradients.

Administrative Districts

Map of Iowa showing Major Land Resource Areas (MLRAs) with labeled regions and color-coded boundaries.
Map depicting Iowa’s Major Land Resource Areas (MLRAs) as defined in 2015.
Map of Iowa showing NRCS administrative areas (2015) with color-coded regional divisions.
Map outlining Iowa’s NRCS administrative areas as of 2015, divided into color-coded regions.

Soil Interpretations

Color-coded map of Iowa showing the spatial distribution of USDA-NRCS Land Capability Classes from Class 1 to Class 8 and water/urban land.
Map displaying the distribution of land capability classes (LCC) across Iowa, used to indicate agricultural suitability and land use limitations.
Map of Iowa showing county-level Carbon Index values with color-coded classifications.
Map displaying Iowa’s Carbon Index by county, highlighting variations in soil carbon potential.

Soil Orders

Table summarizing soil orders in Iowa by acreage and percentage, showing Mollisols as the dominant type, followed by Alfisols and Entisols.
Table showing the total acres and percent share of soil orders in Iowa, based on data compiled from ISPAID in November 2013.
Map of Iowa highlighting the geographic distribution of Alfisols in green, concentrated in eastern and southern regions of the state.
Map showing areas of Iowa where Alfisols are present, based on NRCS and Iowa soil database data from 2013.
Map of Iowa showing the distribution of Entisols, primarily located along river valleys and floodplains, especially in the west.
Geographic map highlighting areas in Iowa where Entisols occur, based on 2014 NRCS and Iowa soil database data.
Map of Iowa showing the distribution of Histosols, with small, scattered blue areas primarily in the north-central region of the state.
Map highlighting locations of Histosols across Iowa, based on USDA NRCS and Iowa soil data.
Map of Iowa showing the distribution of Inceptisols, with orange-highlighted areas primarily along the western edge and scattered central and eastern locations.
Map showing the extent of Inceptisols across Iowa, based on 2013 NRCS data and Iowa soil interpretations.
Map of Iowa showing widespread distribution of Mollisols, marked in brown, covering most of the state except a few river valleys and uplands.
Statewide map showing the extensive coverage of Mollisols—fertile prairie soils—across Iowa, based on USDA NRCS data.

Iowa’s Soil Associations

Two tables listing the top 10 soil map units (SMUs) and soil series in Iowa by total acreage, with Clarion and Fayette as leading entries.
Tables comparing Iowa’s top 10 soil map units (SMUs) and soil series by total acreage, compiled in 2010.

Keys to Iowa’s Soil Associations

These keys provide a simplified way to identify and compare dominant soils within two major soil regions of Iowa: loess-derived soils in the east-central region and prairie-derived upland soils in the northwest. Each key classifies soils based on properties such as parent material, organic matter, drainage, and landscape position. Understanding these associations helps guide land use, management decisions, and conservation planning across Iowa’s diverse agricultural landscapes.

Explore our Map Library to access a wide range of resources, including high-quality images, downloadable GIS data, and our interactive Soilscapes map—designed to visualize soil patterns and land use across Iowa and Nationwide.

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