Soil Suitability Ratings & Interpretations

Key to Soils Within Major Soil Associations of Iowa

  • Prairie-Derived Upland Soils of NW IA - Table (Nov 2006)
  • Loess-Derived Soils of East-Central IA - Table (Jan 2007)

Iowa Corn Suitability Rating 2 (CSR2)

  • CSR2 Equation and Component Values - Equation (Mar 2015)
  • County Weighted Average CSR2 - Map (Apr 2015)
  • ISU Extension: "Computing the Iowa Corn Suitability Rating for Your Farm - Article (Jun 2014)
  • Iowa Farmer Today: "ISU tweaks CSR" - Article (May 2015)
  • Integrated Crop Management NEWS: "CSR2 Equation Updated" - Article (Apr 2015)
  • CSR2 Background, Update, and Frequently Asked Questions - FAQ (May 2013)
  • ISU CALS: "ISU Updates Method for Rating Soil Productivity" - News Release (May 2013)
  • Major Land Resource Areas (MLRA) within Iowa - Map (May 2015)
  • USDA-NRCS Areas and Office Locations within Iowa - Map (May 2015)
  • Average Precipitation for Iowa (1981 - 2010) - Map (Sep 2012)

Iowa Corn Suitability Rating (CSR)

  • County Weighted Average CSR - Map (Apr 2015)
  • Climate Deductions for CSR - Map (Apr 2015)
  • ISU Extension: "Corn Suitability Rating - An Index to Soil Productivity" - PM 1168 (Revised Oct 2012)
  • Average Precipitation for Iowa (1931 - 1960) - Map (Sep 2012)
  • Clarion-Nicollet-Webster Soil Association Area Weather Adjustment Factor for CSR - Map
  • Galva-Primghar-Sac Soil Association Area Weather Adjustment Factor for CSR - Map
  • Marshall Soil Association Area Weather Adjustment Factor for CSR - Map
  • Ida-Monona Soil Association Area Weather Adjustment Factor for CSR - Map
  • Productivity Levels of Some Iowa Soils - Special Report No. 66 (Apr 1971)

Soil Interpretations

Currently there are two different interpretations:

  1. Soil Map Units (SMU’s) requiring Tile Drainage to Achieve Optimal Agronomic Yields for Row Crops and \
  2. SMU’s suitable for Vineyards.

PDF files are available as one file containing all counties in the state or as one file for each individual county. Tables are updated through January 2010.

Soil Resources and Interpretations Maps and Tables:

  • Landform Regions in Iowa - Map
  • Soil Associations of Iowa: STATSGO Database - Map
  • Principal Soil Associations and Major Soil Areas in Iowa - Map
  • Distribution of Alfisols in Iowa - Map (2013)
  • Distribution of Entisols in Iowa - Map (2014)
  • Distribution of Histosols in Iowa - Map (2013)
  • Distribution of Inceptisols in Iowa - Map (2013)
  • Distribution of Mollisols in Iowa - Map (2013)
  • Summary of Soil Orders in Iowa - Table (Nov 2013)
  • The Top 10 Soil Series and Map Units - Table (Mar 2010)
  • County Weighted Average Carbon Index - Map (Apr 2005)
  • Summary of slope ranges within each Slope Class - Table (Oct 2013)
  • By county Land Capability Class (LCC) summary - Table (Jan 2011)

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