Arizona · Soil test

Arizona soil-test fertilizer recommendations

Zone Forge reads your Arizona soil test in Arizona's own calibrated language — the critical levels and rate logic come straight from Arizona — University of Arizona Cooperative Extension (Olsen-P calibration), not a national average. Lime is rarely needed per Arizona's alkaline-soil guidance — no automatic rate is invented.

Critical soil-test levels

  • P: critical 7 ppm (Olsen (NaHCO3))

Per Arizona — University of Arizona Cooperative Extension (Olsen-P calibration) — below the critical level, a yield response to the added nutrient is expected.

Crops covered

Arizona — University of Arizona Cooperative Extension (Olsen-P calibration) rates these crops in Arizona:

AlfalfaBarleyCottonSmall grainsTriticaleWheat

Published source: Arizona — University of Arizona Cooperative Extension (Olsen-P calibration)

Frequently asked

What soil-test method does Arizona use?

Arizona — University of Arizona Cooperative Extension (Olsen-P calibration). Zone Forge cites the publication on every recommendation.

Is the Arizona soil-test calculator free?

Yes — the Arizona soil-test recommendation calculator is free and needs no signup. Enter your lab values for source-cited P and K. Lime is advisory only here — see the Arizona lime guide rather than expecting a numeric calculator rate.

Can Zone Forge calculate a Arizona lime rate?

Usually not. Arizona is an alkaline-soil region — Zone Forge does not invent an automatic lime rate. Review the cited guidance on the Arizona lime guide; if a lab report shows unusually acid soil, confirm with the lab or local Extension before liming.

Zone Forge reads every Arizona soil test in its own state's language, then builds source-cited fertilizer and alkaline-soil lime guidance (no automatic rate) and full variable-rate prescriptions. See the science →