North Carolina's land-grant extension publishes a method — not a one-size-fits-all rate. NCDA&CS Orange Book Part II — Mehlich Buffer acidity equation Ac=(6.6-BpH)×4, Table 2.1 factors, Table 2.2 class target pH (MIN 6.0 / M-O 5.5 / ORG 5.0). Combined source v2.0: lime + Orange Book Table 2.3/2.4 nutrient equations. Live inputs: Mehlich buffer acidity and crop pH goal from North Carolina's published method. Enter the required soil-test values in the free calculator for tons of CaCO₃-equivalent per acre, ECCE-adjusted, with the citation.
Published source: NCDA&CS Agronomic Division — Mehlich-3 + Humic-Matter Lime + Orange Book Crop Fertilization
It depends on the Mehlich buffer acidity value on your lab report and your crop's published pH goal, exactly as North Carolina publishes them. NCDA&CS Orange Book Part II — Mehlich Buffer acidity equation Ac=(6.6-BpH)×4, Table 2.1 factors, Table 2.2 class target pH (MIN 6.0 / M-O 5.5 / ORG 5.0). Combined source v2.0: lime + Orange Book Table 2.3/2.4 nutrient equations. Enter those values in the free Zone Forge lime calculator for tons of CaCO3-equivalent per acre, with the citation.
North Carolina sizes lime from Mehlich buffer / exchangeable acidity per its own published tables. NCDA&CS Orange Book Part II — Mehlich Buffer acidity equation Ac=(6.6-BpH)×4, Table 2.1 factors, Table 2.2 class target pH (MIN 6.0 / M-O 5.5 / ORG 5.0). Combined source v2.0: lime + Orange Book Table 2.3/2.4 nutrient equations. Source: NCDA&CS Agronomic Division — Mehlich-3 + Humic-Matter Lime + Orange Book Crop Fertilization.
Zone Forge computes North Carolina lime from that state's published land-grant method (Mehlich buffer / exchangeable acidity as North Carolina's published lime method reads it, with the crop's published pH goal) — lime calculator, soil-test fertilizer, and full variable-rate prescriptions. See the science →