What should you do about N: Apply more or hope you have enough?
Getting your planting completed has been your top priority this spring, and your number one headache. The weather just has not cooperated. And that has lead to your number two headache this spring, what should you do about nitrogen for corn. Supposedly there was a lot left in the ground that was unused by the 2012 crop. You applied some last fall or this spring. But word is that the heavy rain has washed it out of the field through the tile lines. So what can be done?
Not knowing what your revenue will be this year, and fearing the worst, many farmers do not want to spend unneeded money for nitrogen if it is not needed. But there are no simple soil tests to determine how much nitrogen may be in the ground and available to the corn, once it is planted and growing. For farmers on a tight crop production budget, nitrogen could be a budget killer. Over apply it and you waste money. Under apply it and you lose money.
University of Illinois crop production specialist Emerson Nafziger can commiserate with you about the problem, since you probably had to toss a coin earlier this year on whether to apply nitrogen or plant corn because the calendar was flying by too fast and there was not time to do both, but both had to be done.
When your corn is up and growing, any application of nitrogen will be used because the corn will absorb it before it gets lost. That is the positive thing, says Nafziger, “A plan to split-apply N – right after planting and again at sidedress – might, if the first application couldn’t be made before the crop emerged, now be modified to apply less total N but in a single application.” He says it is important to provide N to the crop before it become deficient, but he also says soils with high organic matter may have enough in a mineralized form to benefit the crop. But he says the mineralization process cannot keep up with the growth and needs of the corn plant.
What nitrogen is left from last year’s crop?
The answer to that is not friendly. There was quite a bit left from last year due to lower demand by a drought-stressed crop, but that surplus has been diminished by the warm-up of the soil and the excessive rains that have absorbed it and carried it out of fields through drainage tile lines. His research earlier this spring at 60 locations around Illinois found that 23 to 38 percent of the nitrogen content present last fall had disappeared. The range varies with the type of soil and the amount of rainfall.