Despite the wet weather many think may be causing nitrogen fertilizer to get away from corn plants, it is still far too early to make that decision.
While it seems likely some nitrogen fertilizer has moved out of the upper soil as a result of rainfall this year University of Illinois Agronomist Emerson Nafziger says if soils dry out, the torrential rains stop, the sun shines, and the weather gets warmer things should be all good, “The crop is going to tell us this. If by the middle of June some of the crop has really greened up nicely and some has not, then we might need to think about those that haven’t and determine if enough nitrogen is missing to cause this to take place. My suspicion is we will not see very much of that at all. If we are warm and dry and with sunshine for a week, I think the crop is going to look good in almost every field.”
My suspicion is we will not see very much of that at all. If we are warm and dry and with sunshine for a week, I think the crop is going to look good in almost every field. - Emerson Nafziger
One indication the topsoil hasn’t been stripped clean of nitrogen is the good recovery of green leaf color. Nafziger says, as soils dry out, root systems start to expand and the color will change. He explains the corn crop at this point looks like it does not because of lack of N, but due to cool temperatures and abundant rainfall. While it is premature to revise nitrogen management based on what has happened so far, Nafziger cautions it cannot be ruled out, “I would be very reluctant now to make a decision that we need to go put more nitrogen on, especially if we’ve already put the full amount on. If we still need to side-dress and we add 10, or 15, or 20 pounds I don’t have a problem with that. But I think it is premature to decide so much of the nitrogen is gone that we put out there that we need to go back and plan to put more on at this point.”
The good news is there is still time to make such decisions. The corn crop takes up barely one pound of N per acre for every inch of growth it makes up to about knee-high.
Nitrogen deficiency develops over time, and Nafziger says it is almost always more related to current soil moisture than to the amount nitrogen in the soil. So, if fields aren’t extra wet or extra dry over the next month, this season could still turn out to be much more typical than many now expect.