Indiana · Soil test

Indiana soil-test fertilizer recommendations

Zone Forge reads your Indiana soil test in Indiana's own calibrated language — the critical levels and rate logic come straight from Tri-State Fertilizer Recommendations (2020), not a national average. Lime has its own live calculator for Indiana with method-specific lab inputs.

See Indiana recommendations → Indiana lime guide

Critical soil-test levels

  • P: critical 20 ppm (Mehlich-3 or Bray-1)
  • K: critical 100 ppm (Mehlich-3 or ammonium-acetate)
  • Mg: critical 50 ppm (Mehlich-3 or ammonium-acetate)

Per Tri-State Fertilizer Recommendations (2020) — below the critical level, a yield response to the added nutrient is expected.

Crops covered

Tri-State Fertilizer Recommendations (2020) rates these crops in Indiana:

AlfalfaCornCorn silageForage legumesGrass haySoybeansWheat

Published source: Tri-State Fertilizer Recommendations (2020)

Frequently asked

What soil-test method does Indiana use?

Tri-State Fertilizer Recommendations (2020). Zone Forge cites the publication on every recommendation.

Is the Indiana soil-test calculator free?

Yes — the Indiana soil-test recommendation calculator is free and needs no signup. Enter your lab values for source-cited P and K; Indiana's live lime calculator is available separately with its own required lab inputs.

Can Zone Forge calculate a Indiana lime rate?

Yes — the free soil-test calculator covers source-cited P and K. Indiana also has a live lime calculator on Zone Forge that uses the state's published method. Open the Indiana lime guide or lime calculator for tons of CaCO3-equivalent per acre.

Zone Forge reads every Indiana soil test in its own state's language, then builds source-cited fertilizer and a live lime calculator and full variable-rate prescriptions. See the science →