Fertilizer application timing directly affects nutrient use efficiency and cost per unit of yield. This guide covers optimal timing for nitrogen, phosphorus, potassium, and sulfur across corn, soybeans, and wheat.
Optimal fertilizer timing by nutrient and crop: Nitrogen in corn — anhydrous fall or spring pre-plant + UAN side-dress at V4-V6. Phosphorus — broadcast in fall or incorporated spring pre-plant. Potassium — fall broadcast for corn, any time post-harvest for soybeans. Sulfur — spring pre-plant or UAN blend at side-dress timing.
| Nutrient | Best timing | Flexibility |
|---|---|---|
| Anhydrous ammonia (corn N) | Fall (soil <50F) or spring pre-plant | Low — soil temp critical |
| UAN side-dress (corn) | V4-V6 (5–7 leaf) | Medium — timing window |
| Phosphorus (DAP/MAP) | Fall broadcast or spring pre-plant | High — not timing sensitive |
| Potassium (MOP) | Post-harvest fall or spring | High — low leaching risk |
| Sulfur | Spring pre-plant or with N side-dress | Medium |
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