Calculate Phosphorus Application

Calculate Phosphorus Application

IMPORTANT NOTE: The application rate that this form suggests is for correcting an imbalance only and does not include fertilization for crop removal. Please refer to our Application Guide which provides fertility programs for various crops.

1. Find the method that was used to determine your phosphorus (or phosphate) level.
2. Determine the status (e.g., VL, M, etc.) or use the status given on the lab report.

Typically, soil test reports express phosphorus (P) in parts per million (ppm). Sometimes P levels are reported in pounds per acre (ppa).
To convert ppa P or ppa P2O5 to ppm P, Click here
NOTE: Status values are in part per million (ppm)

Status Bray 1 Bray 2 Olsen P Mehlich 1 Mehlich III Morgan P
Very low 0 – 8 0 – 11 0 – 3 0 – 5 0 – 13 0 – 3
Low 9 – 17 12 – 25 4 – 7 6 – 15 14 – 30 4 – 8
Medium 18 – 26 26 – 42 8 – 13 16 – 30 31 – 50 9 – 20
High 27 – 39 43 – 59 14 – 22 31 – 50 51 – 100 21 – 41
Very high 40+ 60+ 23+ 51+ 101+ 42+

3. Use the form below to determine how much phosphate (P2O5) is needed (use the Average for mixed crops).

To convert ppm P to ppa P2O5, multiply by 4.6
To convert ppm P to ppa P, multiply by 2.3

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