Nitrogen Management

Nitrogen is the most difficult nutrient that we try to manage. When the soil gets above about 55 degrees Fahrenheit, nitrogen becomes dynamic. Lots of N fertilizer contains at least some N in the Ammonia form. NH3 applied to the soil quickly becomes NH4+ and attaches to clay particles. As soon as temperatures are warm enough, the ammonia form is converted (nitrified) and becomes easier for most plants to take up. It also is very soluble and can move up and down in the soil profile with water. It is also subject to denitrification and converted to nitrite, nitrous oxide, and N all of which escape to the atmosphere. The hard part is predicting when all this will happen and how it will affect the crop. These changes are all subject to weather. The most certain way we have to manage nitrogen in my opinion is by using the pre-sidedress nitrogen test (PSNT) and sidedressing. The downside of that is that the window is pretty narrow for sampling and applying. With Nitrogen costs fairly high and environmental concerns needing to be addressed, minimizing fertilizer nitrogen is important. I also think that in order to push the envelope on 300 bushel corn, we will need to look at getting the N to the plant when it needs it.