CSR2 is a corn suitability rating calculated using six parameters. The “perfect corn producing” soil gets a rating of 100. A soil having nearly no potential to grow corn receives a rating of 5. Most soils have ratings somewhere in between. CSR2 is calculated on a map unit (MU) basis using the maps and data of the Iowa Cooperative Soil Survey (ICSS). Since the ICSS includes several agencies with sometimes slightly different data there are two ways it can be calculated. The first is CSR2-ISU, which assumes a MU is the soil series listed in the MU name. The second is CSR2-NRCS, which uses an area-weighted average of a MU that takes into account both the dominant soil and inclusions of other soils. The amount and types of inclusions as well as all other information used in CSR2-NRCS is available in USDA-NRCS Web Soil Survey. For most soils CSR2-ISU and CSR2-NRCS have comparable values. Cases where the two values differ by more than one or two points are when the MU has a high percentage of inclusions, has incomplete or conflicting data in Web Soil Survey, is on C-slope, or formed in very clayey or sandy parent materials. CSR2-ISU considers C-slopes reduce corn productivity by 15 points relative to nearly level land. CSR2-NRCS considers the reduction to be 10 points.