Iowa's land-grant extension doesn't use a one-size-fits-all number — it uses a published method. Iowa State Extension PM 1688. 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: Iowa State PM 1688
It depends on your soil's buffer/acidity reading and your target pH — Iowa publishes a method, not a single 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: Iowa State PM 1688.
Zone Forge computes every Iowa recommendation from that state's own published land-grant method — lime, soil-test fertilizer, and full variable-rate prescriptions. See the science →