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How does the Custom calculator determine my phosphorus needs?

The Custom calculator can be used to help create phosphorus recommendations for your fertility strategies.

The Custom calculator utilizes the following equations:

Nutrient

Crop

Build/Maintenance

Phosphorus

Corn

Bray P1 or Mehlich 3-COL:

If STP < = OPTL then P Rec = (OPTL - STP) * 20 / Years + (Yield * 0.37)

If STP > OPTL and STP <= OPTH then P Rec = (Yield * 0.37)

If STP > OPTH and STP <= OPTH + 10 then P Rec = (Yield * 0.37) - ((Yield * 0.37) * (STP - OPTH)) / 10

Mehlich 3-COL: STP = (0.84 * STP as M3-COL) + 1.21

Olsen Bicarbonate: STP = (2.27 * STP as Olsen) - 7.045

Mehlich 3-ICP: STP = (0.778 * STP as M3-ICP) - 6.4667

Phosphorus

Soybeans

Bray P1 or Mehlich 3-COL:

If STP < = OPTL then P Rec = (OPTL - STP) * 20 / Years + (Yield * 0.80)

If STP > OPTL and STP <= OPTH then P Rec = (Yield * 0.80)

If STP > OPTH and STP <= OPTH + 10 then P Rec = (Yield * 0.80) - ((Yield * 0.80) * (STP - OPTH)) / 10

Mehlich 3-COL: STP = (0.84 * STP as M3-COL) + 1.21

Olsen Bicarbonate: STP = (2.27 * STP as Olsen) - 7.045

Mehlich 3-ICP: STP = (0.778 * STP as M3-ICP) - 6.4667

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