Illinois's land-grant extension doesn't use a one-size-fits-all number — it uses a published method. Illinois Agronomy Handbook Ch. 8 — water pH × CEC soil class (A-E) lookup. Enter your soil-test values in the free calculator and Zone Forge returns tons of CaCO₃-equivalent per acre, ECCE-adjusted, with the citation.
Published source: Illinois Agronomy Handbook — Chapter 8 (Managing Soil pH and Crop Nutrients)
It depends on your soil's buffer/acidity reading and your target pH — Illinois publishes a method, not a single number. Illinois Agronomy Handbook Ch. 8 — water pH × CEC soil class (A-E) lookup. Enter your values in the free Zone Forge lime calculator for tons of CaCO3-equivalent per acre, with the citation.
Illinois Agronomy Handbook Ch. 8 — water pH × CEC soil class (A-E) lookup. Source: Illinois Agronomy Handbook — Chapter 8 (Managing Soil pH and Crop Nutrients).
Zone Forge computes every Illinois recommendation from that state's own published land-grant method — lime, soil-test fertilizer, and full variable-rate prescriptions. See the science →