An application of fertilizer between the rows of growing crops is known as a "sidedress" application. The application of N fertilizer between the rows of a growing corn crop is the most common sidedress application on dairy farms.
The decision to make a sidedress N application should be based on a Pre-Sidedress Nitrate Test (PSNT). This test assesses whether or not the corn crop will have a yield response to the addition of sidedress N. If the PSNT indicates that a yield response is likely, then the sidedress application of N should be made when the corn is 12-24 inches tall. This roughly represents the last time we can access a corn field to apply N before the crop moves into a phase of high N demand. Sidedress N applications are geared to supply N when the crop needs it and can handle it (i.e. ample root system, ability to photosynthesize, etc.), so it's highly efficient.
Nitrogen can be sidedressed using three methods:
1. Urea Ammonium Nitrate (UAN) solution can be applied with a pesticide sprayer fitted with drop nozzles. The solution is dribbled on the soil surface.
2. Urea Ammonium Nitrate (UAN) solution can also be injected into the soil between the rows with disc openers.
3. Anhydrous Ammonia is another N fertilizer used in sidedress applications. Use of anhydrous ammonia is on the decline, because it poses a risk to the applicator, must be injected, and transport over the road is regulated.
What are the pros and cons of sidedress nitrogen applications?
Continue to the next pages for a focus on fertilizer materials.