How do I Manage Multiple Variable-Rate Nitrogen Applications on the Same Field?
In GA+N, each Nitrogen Card simulates independently, using only the information available up until the planned application date. A first nitrogen card on a given field does not know that the second (if present) will take place when it simulates. This principle has implications for managing multiple Variable Rate Nitrogen Prescriptions (VRN Rx) on the same field in the same season.
Scenario 1: A user plans to run one VRN Rx for the season to meet the field's entire nitrogen need. The Rx is exported and applied. Then, through the season, environmental factors reduce nitrogen availability below original expectations. For that user, it makes the most sense to run the second nitrogen application without adjusting the first. This accurately reflects what happened in the field - the first application was fully applied, weather events took place and were incorporated into the model, a need for additional nitrogen arose, and a second Rx is run to meet that need.
Scenario 2: A user plans from the beginning - before applying any product in the field - to run multiple VRN Rx, distributing the full nitrogen need across the season. Each Rx has a separate VRN card on the GA+N Fields List. Each Rx simulates independently. The second Rx chronologically includes the first in its calculations. The first Rx does not recognize that the second will take place, because it exists beyond the end of its simulation. Therefore, it is necessary to adjust the first Rx before running the second. We will break this down in the procedure below.
- Follow this workflow in order:
- Verify which scenario (above) applies to you.
- Follow the linked instructions to apply the first VRN Rx card.
- Wait for the first VRN Rx to show a product rate and N rate on the Rx card (no longer says "running Rx").
- If scenario 1 applies to you, skip to step 5. If scenario 2 applies, proceed to step 4.
- Follow the linked instructions to adjust the first VRN Rx
- Reduce the Rx by a flat rate or percent.
- The amount or rate depends on how you plan to distribute your two VRN applications.
- Note: Use "Select All" in the rates legend on the zone map to select and adjust all regions.
- Repeat steps 1-2 to create and run a second VRN Rx application.
- How Do I Add New Planting or Nitrogen Events?
- How do I View the Season Chart, VT/R1 Map, and Run Simulations?
- How do I Edit Variable Rate Nitrogen Events?
- How do I Edit, Deactivate, or Delete Existing Nitrogen or Planting Events?