The equation for calculating Iowa’s Corn Suitability Ratings (CSR) was recently updated and designated Corn Suitability Rating 2 (CSR2). The updated equation provides every user an opportunity to calculate the rating for each soil map unit identified in Iowa. Corn Suitability Rating 2 remains an index to the inherent soil productivity of each kind of soil for row crop production. The index is scaled from 100, for the most productive soils, to 5 as the least productive.