Idaho's land-grant extension doesn't use a one-size-fits-all number — it uses a published method. Enter your soil-test values in the free calculator and Zone Forge returns tons of CaCO₃-equivalent per acre, ECCE-adjusted, with the citation.
Northern Idaho uses Modified Mehlich / SMP / Sikora and DOES need lime. Southern Idaho has calcareous soils and rarely needs lime.
Published source: University of Idaho — Northern ID (dryland Palouse) + Southern ID (irrigated Snake River Plain) Fertilizer Guides
It depends on your soil's buffer/acidity reading and your target pH — Idaho publishes a method, not a single number. Enter your values in the free Zone Forge lime calculator for tons of CaCO3-equivalent per acre, with the citation.
Source: University of Idaho — Northern ID (dryland Palouse) + Southern ID (irrigated Snake River Plain) Fertilizer Guides.
Zone Forge computes every Idaho recommendation from that state's own published land-grant method — lime, soil-test fertilizer, and full variable-rate prescriptions. See the science →