Soil Productivity Index Ratings for Illinois Soils
You have reached the web page for the Soil Productivity Index Ratings for Illinois soils. This information was published in August of 2000 in two research bulletins by the Office of Research, College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana-Champaign. The Bulletins listed below are linked to files that can be read using an Adobe Acrobat Reader. The table of contents are linked to the specific pages, text, tables or figures. Once selected, the page can be enlarged or printed. The crop, pasture, and forestry yields and productivity index ratings in Bulletin 810 are for the average level of management used by all farmers in Illinois in the 1990s. The crop yields represent a mean annual yield for a 10-year period. Bulletin 811 provides crop yields and productivity indices under an optimum level of management used by the top 16% of farmers in Illinois in the 1990s.
Prime agricultural land classes (Class A, Class B, and Class C) previously provided in Circular 1156 (Soil Productivity in Illinois) were not included in Bulletin 811. The prime agricultural class of any soil type can be determined by using the optimum productivity index (PI) shown in Table S2 of Bulletin 811 and the following author recommended prime agricultural class scale. Soil types with optimum PI's from 133-147 are in Class A, from 117-132 are in Class B, and from 100-116 are in Class C. Soil types in Bulletin 811 with optimum PI's equal to or below 99 are in the other agricultural land class and not considered prime agricultural land. If the soil type is in a soil map unit which is not on A slope or not slightly eroded, the user will need to determine if the soil type has a favorable or unfavorable subsoil for rooting (3rd column in Table S2 of B811) and make an erosion and/or slope adjustment using either Figure S1 (B811) or Table S3 (B811) prior to utilizing the scale and prime agricultural land class limits provided above.
Since the year 2000, more than 80 new soil types and soil complexes have been identified on Illinois county soil survey maps. Crop yields and productivity ratings under both average management (B810, Table 2 revised) and optimum management (B811, Table S2 revised) have been added to the existing values provided either in the published paper copies of the Bulletin 810 and Bulletin 811 or the previously revised tables (in 2001) within the electronic copies of these Bulletins linked to this soil productivity web site. All new soil symbols are followed by an "*". Please click on either Bulletin 810, Table 2 revised or Bulletin 811, Table S2 revised links provided below if you can not find the appropriate soil ratings (crop yields and PI’s) in electronic copy (.pdf) of B810 and B811 which is also linked to this web page.