v1.0 (2026-05-23) · MSU Soil Fertility publishes a pH-only wheat-country rule: `tons CaCO3/A = 1.5 × (target pH − current pH)`, with the cited wheat field evidence targeting pH 6.0. Other crops and higher-precision needs stay with an outside soil lab rather than borrowing an uncited crop goal. Cropland acidification has spread across central/northern MT wheat country from decades of ammonium-N; eastern MT and irrigated valleys may still be alkaline.
This source publishes a state method — its crop-specific rate tables are maintained in the extension bulletin rather than a fixed crop list, so Zone Forge doesn't claim a crop set here.
Lime calculator. Zone Forge computes this source's published lime rates in-app and cites the method.
Yes — Zone Forge's calculators are free and need no signup. This page shows the states and crops Montana State University — Soil acidification rule (1.5 × ΔpH) covers so you can verify the source behind your recommendation.
Browse the full Coverage Explorer — every state, crop and source — or see the science →