Iowa's land-grant extension publishes a method — not a one-size-fits-all rate. Iowa State Extension PM 1688. Live calculator uses this state's published method and citation. Enter the required soil-test values in the free calculator for tons of CaCO₃-equivalent per acre, ECCE-adjusted, with the citation.
Published source: Iowa State University Extension — PM 1688: A General Guide for Crop Nutrient and Limestone Recommendations in Iowa
It depends on the inputs Iowa's land-grant method publishes — not a single national number. Iowa State Extension PM 1688. Enter your values in the free Zone Forge lime calculator for tons of CaCO3-equivalent per acre, with the citation.
Iowa State Extension PM 1688. Source: see the calculator citation. Source: Iowa State University Extension — PM 1688: A General Guide for Crop Nutrient and Limestone Recommendations in Iowa.
Zone Forge computes Iowa lime from that state's published land-grant method (the lab values required by this state's published method) — lime calculator, soil-test fertilizer, and full variable-rate prescriptions. See the science →