Side-Dressing Corn

Side-dressing corn in central IllinoisIt’s now been about six weeks since the corn was planted. Last weekend (May 21 and 22), the farmers side-dressed most of the corn on the farm (I say most because they had issues with a hydraulic line and had to repair that before they were able to finish last week 😉 ).

We side-dress on our farm because of the way we split up nitrogen applications. You may have heard of plants that are able to “fix” their own nitrogen. Those are called legumes and include species like peas, peanuts, and soybeans, which are able to use the nitrogen in the soil and turn it into a usable form of nitrogen through soil bacteria. Corn is not a legume and depends on the usable nitrogen that we add to the soil via fertilizer. Some farmers do add a small amount of nitrogen fertilizer to their soybeans, but we only add it to our corn. The farmers on our farm don’t add the nitrogen fertilizer all at once so that we don’t “lose” nitrogen through reactions in the soil. The nitrogen would still be there, but the corn wouldn’t be able to use it.

Like I mentioned in the pre-planting decisions post earlier in this series, anhydrous ammonia (a nitrogen fertilizer) was applied to the field last fall. That was the first application for this crop and amounted to 70 pounds of nitrogen per acre. Another round of nitrogen went on with the burndown herbicide in the form of “liquid 28” (or 28% UAN, a type of nitrogen fertilizer, mixed with the herbicide and lots and lots of water). Nitrogen works as a carrier with the burndown herbicide, helping the herbicide get where it needs to be. This round of UAN added 60 pounds of nitrogen per acre to the field.

Tractor side-dressing corn

The lines next to each row are where the nitrogen fertilizer was injected into the soil.

When the farmers side-dressed, they applied 28% UAN. Like I kind of mentioned before, this specific mix of UAN contains 28% nitrogen and 72% water and is in liquid form. The rate of nitrogen applied in the corn-field-by-the-round-crib was 50 pounds per acre. The 28% UAN in the tank was actually diluted with a bit more water so that the right amount of nitrogen would be applied (so the total amount of nitrogen in the tank was a bit less than 28%). The actual process of side-dressing involves taking a tractor and tank across the field, injecting (also called “knifing”) the liquid UAN into the soil close to the row of growing corn. The corn was probably about 6 to 8 inches tall when the farmers side-dressed this field. The farmers had to be really careful to keep the tractor tires between the rows of corn and to make sure that the knives on the toolbar didn’t rip up rows of corn. The plants are big enough at this point that they would probably not fully recover from being run over with that amount of weight (don’t worry, the farmers here have lots of experience doing this and didn’t damage any corn…that I found anyway 😉 ).

Toolbar used to side-dress corn

Here’s a view of the tank and toolbar being pulled by the tractor. You can see the lines behind the disks (knives) that run along the toolbar and are connected to the tank.

If you were doing the math in your head, you’d know that we are up to 180 pounds of nitrogen per acre applied for this crop this season. Normally on our farm, 170 pounds of nitrogen is as much as we apply in a season. Fortunately, the farmers were able to get the corn in the ground a lot earlier than usual and the corn has been looking really good, so the farmers are considering maybe even adding a bit more nitrogen in a couple of weeks (about 20 pounds or so), depending on how the corn looks then. The farmers are seeing signs of promising yields that have potential to be higher than normal, so they want to add that couple of pounds of nitrogen to help boost that yield. Now is the time to get the nitrogen added since it’s difficult (and really not worth it) to drag special equipment over a fully-grown 8-foot-plus tall field of corn later in the season, so it takes a bit of predicting and a whole lot of faith. Nitrogen fertilizer does cost money, so the farmers aren’t going to apply it unless they think that they will yield higher than break-even with the additional application.

Here’s a short video my dad (one farmer) recorded while my uncle (the other farmer) was side-dressing the nitrogen:


Coming up in the next couple of weeks:

  • Post-emergence herbicide.  We had a couple of inches of rain this Memorial Day weekend and there is more in the forecast for this week. A second herbicide application will go on as soon as it dries out, which probably won’t be any earlier than Friday (first week of June). A local fertilizer/chemical business our farm works with and buys product from will apply the herbicide for the farmers. This will kill any weeds that have germinated and started growing since the burndown herbicide went on before planting.
  • Potential additional nitrogen application. If the farmers decide to add some more nitrogen, this will probably happen around the third week of June. Just depends on how the corn looks and what pans out with the weather in mid-June.
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1 Comment

  • Reply
    Mark Lambert
    May 31, 2016 at 2:03 pm

    And people thought this “farming” stuff was easy. Love the step by step tour of the growing season and the simple explanations of what you are doing and why. Keep up the good work.

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