Soil Survey & Digital Soil Data: Soil Suitabilities & Interpretations

Key to Soils Within Major Soil Associations of Iowa

• Prairie-Derived Upland Soils of NW IA (PDF)
• Loess-Derived Soils of East-Central IA (PDF)

Weighted Average Corn Suitability Ratings

• County Weighted Average Corn Suitability Rating (PDF)
• Download Extension publication “Corn Suitability Ratings -- An Index to Soil Productivity”

Weather Adjustment Factors for Corn Suitability Ratings by Soil Association Area

• Clarion-Nicollet-Webster Soil Association Area Weather Adjustment Factor for CSR (PDF)
• Galva-Primghar-Sac Soil Association Area Weather Adjustment Factor for CSR (PDF)
• Marshall Soil Association Area Weather Adjustment Factor for CSR (PDF)
• Ida-Monona Soil Association Area Weather Adjustment Factor for CSR (PDF)

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:

• Major Land Resource Areas (PDF)
• Soil Associations of Iowa: STATSGO Database (PDF)
• Slope Class Table (PDF)
• Iowa Carbon Index (PDF)
• Principal Soil Associations and Major Soil Areas of Iowa (PDF)
• Summary of Land Capability Class (LCC) for Iowa counties (PDF)
• Top 10 Soil Series and Map Units (PDF)
• Iowa Soil Orders (PDF)