Corn N Sidedress Options

Jun 19, 2015
By Dave Franzen
NDSU Extension Soil Specialist
Many more growers are planning to sidedress corn this year than in the past. Most growers that have tried sidedressing the past few years have been successful at increasing corn yield over fields with preplant only. I will mention the few that had issues later on.
My first preference would be either anhydrous ammonia or coulter applied UAN in soils that do not have high clay. Either of these could be set up to apply every other row. Anhydrous ammonia is always applied at least 4 inches deep, with a row closure tool behind if anyone believes me. Coulter applied UAN can be applied shallow if the soil is wet, but apply deeper if the soil is dry. The coulter applied UAN option is more versatile than the anhydrous because it is possible to add S fertilizers to liquid when it not possible to do so with anhydrous without a second trip. In high clay soils, the coulter applied UAN is a better option and performs well if the surface inch or two is dry. Last year (every year is different and how we make anything work here is a miracle because of the uncertainty of weather) some coulter UAN applications smeared the application sides when it was so wet in June and then it immediately dried out, stranding the fertilizer in the slot. The results were not good. So if it is really wet in parts of a high clay field, pulling the coulter out of the ground and just letting the fertilizer stream on top might be the best option. In most years, it will rain even if the fertilizer is smeared in trench and move out of it. It was just the unfortunate circumstance that last year, late sidedressed corn suffered from the rainfall suddenly turning off.
Another option, and one that always worked for me in my prior fertilizer retailer life and here as a researcher except for 2012, is streaming between the rows with UAN.  This is simple to set up and works if it rains within a week after application. The year it didn’t work well, 2012, the efficiency of the application dropped to 20% when I usually figure on 60%.
Now for Y-Tubes; as a retailer/soil sampler/agronomist in Central Illinois from 1976 to 1994, almost every morning when I walked into a corn field I was wet to my thighs within 100 feet. It is a very high humidity region, with low lying fog many mornings. The water drips down the corn stalk and ‘irrigates’ the plant. The Y-Tubes are designed to make use of this feature. It might come to a shock to many people, but we really aren’t Illinois, even though we plant corn and soybeans, practice precision nutrient management and tile drain these days (I was hired at NDSU in spite of my knowledge of these things the committee thought I would never use). A high humidity day here is a refreshingly dry day near Champaign (ask Dr. Zollinger sometime about his speaking experience one summer in Dewey, IL, just ¼ mile from where I used to be headquartered). We have a few mornings in North Dakota where there is dew on corn leaves, particularly the day after a rain, but usually the corn is dry. There is no irrigating stream every morning to move new UAN from a Y-Tube down to the roots. So in our environment streaming between the rows would work just as well- and cost incredibly less.
Lastly, application of up to 60 pounds of N as urea, treated with a urease inhibitor like Agrotain* or Limus*, is possible broadcast over the top of the corn, or a combination of urea and ammonium sulfate up to 60 pounds of N per acre total. It has to have rain to work, but all of these methods need a rain except for the under the soil anhydrous ammonia and coulter applied UAN.
*Mention of a product name is not an endorsement of the product.
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