Zone Forge reads your California soil test in California's own calibrated language — the critical levels and rate logic come straight from California — UC ANR / CDFA-FREP / UC Davis Nutrient Management (Olsen-P calibration + commodity manuals), not a national average.
Published source: California — UC ANR / CDFA-FREP / UC Davis Nutrient Management (Olsen-P calibration + commodity manuals)
California — UC ANR / CDFA-FREP / UC Davis Nutrient Management (Olsen-P calibration + commodity manuals). Zone Forge cites the publication on every recommendation.
Yes — the California 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 California soil test in its own state's language, then builds source-cited fertilizer and lime recommendations and full variable-rate prescriptions. See the science →