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.

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.

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, K and lime guidance.

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