Montana · Soil test

Montana soil-test fertilizer recommendations

Zone Forge reads your Montana soil test in Montana's own calibrated language — the critical levels and rate logic come straight from Montana State University Extension — EB0161 Fertilizer Guidelines for Montana Crops, not a national average. Lime has its own live calculator for Montana with method-specific lab inputs.

Critical soil-test levels

  • P: critical 16 ppm (Olsen P (NaHCO3) on calcareous Montana soils)
  • K: critical 250 ppm (NH4OAc-exchangeable K (ppm))

Per Montana State University Extension — EB0161 Fertilizer Guidelines for Montana Crops — below the critical level, a yield response to the added nutrient is expected.

Crops covered

Montana State University Extension — EB0161 Fertilizer Guidelines for Montana Crops rates these crops in Montana:

AlfalfaBarleyBuckwheatCanolaCornCorn silageDry beansFlaxGrass hayLentil, Chickpea and PeaMilletOatsPotatoesSafflowerSoybeansSugar beetsSunflowerWheat

Published source: Montana State University Extension — EB0161 Fertilizer Guidelines for Montana Crops

Frequently asked

What soil-test method does Montana use?

Montana State University Extension — EB0161 Fertilizer Guidelines for Montana Crops. Zone Forge cites the publication on every recommendation.

Is the Montana soil-test calculator free?

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

Can Zone Forge calculate a Montana lime rate?

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

Zone Forge reads every Montana 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 →