Corn Suitability Ratings

A wide rural field with a dirt path running through harvested farmland under a cloudy sky.

CSR2 (Corn Suitability Rating 2) is an index used in Iowa to rate the productivity potential of soils for row-crop agriculture, especially corn. It ranges from 5 to 100, with higher values indicating better soil quality and yield potential. CSR2 is based on soil properties, climate, slope, and landscape position, and provides a standardized way to compare farmland productivity across the state. It replaced the original CSR system to improve consistency and transparency using updated soil data and models.

CSR2 Equation & Explanation

CSR2 = S-M-W-F-D ± EJ

Where:

S – is the taxonomic subgroup class of the series of the soil map unit (MU),

M – is the family particle size class,

W – relates to available water holding capacity of the series

F – is the field condition of a particular MU, for example, slope, flooding, ponding, erosion class and topsoil thickness,

D – is the soil depth and tolerable rate of soil erosion,

EJ – is an expert judgment correction factor. EJ is normally used with parent materials that have very high bulk density and/or are unusually clayey or sandy.

Restored 1950 Allis-Chalmers WD tractor parked in front of a cornfield.

Corn Suitability Ratings

CSR2 Equation & Explanation

County Weighted Average CSR2

Iowa CSR2 Distribution

CSR2 and Related Resources

CSR2 Equation and Methodology

Guides and Articles

Comparison and Background