How does the Iowa calculator determine my phosphorus needs?
Overview:
The Iowa calculator can be used to help create phosphorus recommendations.
Answer:
The Iowa calculator utilizes the following equations:
|
Nutrient |
Crop |
Build/Maintenance |
|
Phosphorus |
Corn |
Bray P1 or Mehlich 3-COL: if STP < 16 then P Rec = (109.6 - (4.52 * STP)) / (1 - (0.0223 * STP); if STP >= 16 and STP < 21 then P Rec = (0.32 * Yield) Olsen Bicarbonate: If STP < 10 then P Rec = (110.5 - (6.90 * STP)) / (1 - (0.0286 * STP); if STP >= 10 and STP < 14 then P Rec = (0.32 * Yield) Mehlich 3-ICP: If STP < 26 then P Rec = (108.5 - (3.05 * STP)) / (1 - (0.0192 * STP); if STP >= 26 and STP < 36 then P Rec = (0.32 * Yield) |
|
Phosphorus |
Soybeans |
Bray P1 or Mehlich 3-COL: If STP < 16 then P Rec = (86.5 - (4.32 * STP)) / (1 - (0.0352 * STP); if STP >= 16 and STP < 21 then P Rec = (0.72 * Yield) Olsen Bicarbonate: If STP < 10 then P Rec = (86.8 - (6.85 * STP)) / (1 - (0.0545 * STP); if STP >= 10 and STP < 14 then P Rec = (0.72 * Yield) Mehlich 3-ICP: If STP < 26 then P Rec = (85.8 - (2.77 * STP)) / (1 - (0.0253 * STP); if STP >= 26 and STP < 36 then P Rec = (0.72 * Yield) |
