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Dry soil from a local farm that does not use cover crops and regularly tills the soil with machinery, is seen at the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service soil health demonstration event “The Bundled Benefits of Soil Health” on Thursday, September 18, 2014 in the People’s Garden, at the USDA headquarters, in Washington, D.C. One hour ago this soil received two inches of rain.  If it were not for the pan it sits in there would be no trace of moisture along the edg

Illinois Suite of Maps

These maps were produced from data available from the USDA-Natural Resources Conservation Service Soil Data Mart. Please send your comments to Ron Collman, State Soil Scientist.

Ron Collman

State Soil Scientist

Contents 

Soil Order

Illinois taxonomic soil order map
  • Mollisols are soils formed under prairie vegetation, characterized by dark, surface horizons
  • Alfisols are soils formed under forest vegetation
  • Entisols are young soils, typically alluvial or disturbed, that show limited signs of soil development
  • Inceptisols show more signs of soil development than Entisols
  • Histosols are organic soils

Prime Farmland

prime farmland map of illinois
prime farmland map of Illinois

 Prime farmland is land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber and oilseed crops.

Farmland of statewide importance is land other than prime farmland or unique farmland but that is also highly productive.

Hydric Soils

Illinois hydric soils map

 Hydric soils are soils that are saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part. They make up part of the criteria for the identification of wetlands.

Floodplain Soils

Map of Illinois floodplains

Soils that are classified as 'fluvic' at the suborder or subgroup level in Soil Taxonomy, or have a flooding phase in the soil map unit name. 

Drainage Class

Illinois drainage class map

Potential Tile Drainage Extent

illinois map of potential for existing tile drainage
Illinois map of potential for existing tile drainage

This map is an interpretation of the soil groups in the Illinois Drainage Guide. It was assumed that very poorly and poorly drained soils that are rapidly permeable to moderately slowly permeable would be very likely to be tile drained. Soils that are somewhat poorly drained, that are rapidly permeable to moderately slowly permeable are likely to be tile drained. Soils that are slowly or very slowly permeable are unlikely to be tile drained. This has not been verified and is to only be used as a general guide. 

Potential Native Vegetation

Map of illinois native vegetation potential

Taxonomic classification, based on soil taxonomy was used to predict native vegetation. Native in this case would be considered the period of time after transition from a tundra biome ~12,000BP, after the last glacial advance, to forest and grassland biomes. General interpretation rules:

  • - Alfisol order - Woodland
  • - Mollic subgroups of the Alfisol order - Savanna
  • - Mollisol order - Prairie
  • - Entisol order - Woodland
  • - Inceptisol order - Woodland
  • - Histosol order - Marshland


Alluvial soils were interpreted as being Woodland independent of soil classification. This is a generalization, but given the dynamic nature of alluvial systems, there wasn't an adequate way to differentiate the variable vegetation types that may have been present on these types of soils prior to widespread settlement.

Productivity Index

Illinois map of optimum productivity index

Map is based on the Soil Productivity Index for optimal levels of management as described in Bulletin 811, developed by the University of Illinois. Areas that are white were not rated and include water bodies, disturbed soils or soils that commonly have flooding of long duration. Local officials are responsible for the assignment of a Productivity Index for each soil map unit within a county. This map was developed by NRCS for descriptive purposes only. 

Ecotypes

Illinois map of potential ecotypes