v1.4 (2026-08-23) · Eastern Corn Belt fertility recommendations from Ohio State, Purdue, and Michigan State extension. Build-and-maintain philosophy with explicit critical and maintenance ranges. Authoritative for P/K/Mg/S in OH/IN/MI; reasonable proxy for Mid-Atlantic until Penn State table is selected. This is a soil-fertility recommendation source; it is intentionally NOT a nutrient management plan (NMP) and does not encode state P-Index, NRCS 590, or manure application limits.
Build-up to target. Zone Forge computes this source's supported nutrient rates in-app and cites the published method. Its published lime method is computed in-app too.
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