The 4R nutrient management principle teaches us that among all the things one can get right – and wrong – about nutrient application, the time of year is definitely one of them.
After all, “right time” is just one of the four “rights” one must strike.
What the right time is can depend on many factors – the nutrient type, the nutrient source, the land, the slope and more. It doesn’t necessarily mean one time of year is better than another, but it does mean that nutrients applied during the fall might need to be treated differently than those applied in spring.
Now, Illinois research shows fall-applied nitrogen is more likely to contribute to nutrient runoff than spring-applied nitrogen.
A five-year study from the Illinois Fertilizer and Chemical Association, which runs annual N-rate trials, found fall-applied nitrogen lost roughly 12 pounds more per acre through drain tile, or seven percent of the fertilizer. Lowell Gentry, research agronomist and retired University of Illinois principal research specialist, says this represents almost 40 percent of tile nitrate load.
However, despite the potential environmental impacts of greater nutrient loss, Gentry observed that there was no correlating yield loss.
