Authored by: Kevin Owens
Edits by: Pierce Young
Why top dress your grains with nitrogen?
Nitrogen is important to leaf growth and as a building block for proteins, once a plant has germinated. Certain plants like clover, and other legumes, produce their own nitrogen. However, plants like grains and brassicas benefit from added nitrogen inputs due to their high usage of the nutrient.
How you should manage nitrogen applications for grains:
Since nitrogen only benefits plants that have already germinated and produced leaves, it's best to apply nitrogen fertilizers after emergence. Unlike phosphorous and potassium, nitrogen fertilizers are very volatile and will not stay in the ground if there are no plants to use them. It's recommended to use a “split application” on food plots with grains (wheat, oats, cereal rye), where you apply half of the fertilizer after the seeds have germinated and the other half midway through deer season (December). The applications may be applied by broadcasting a nitrogen fertilizer (like Urea 46-0-0) with a seed spreader over the top of your food plots. After the root systems become more developed they are able to take in the additional nitrogen easier during the second application. Applying the second application of nitrogen during the cooler months will also allow for less potential nitrogen loss due to volatilization. This timing will also increase grain health needed to handle potentially more extreme low temperature conditions.
A good way to tell if grains (especially wheat) are nitrogen deficient is if they are starting to look yellow in color due to denitrification (process of converting nitrogen to gases or oxides). This is more common in wet or sandy areas.
The rate of application for nitrogen should be based upon a soil test taken before planting (often 30-40 lbs/acre of Nitrogen; equivalent to 1.3-2.2 bags/acre of Urea).
It is also recommended not to use fertilizers that contain sulfur (like Ammonium sulfate 21-0-0), since a study at the MSU Deer Lab showed deer avoiding food plots with high sulfur concentrations in the soil.
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