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Post N for Wheat, Corn, Sunflower, Other (07/04/19)

After a tour June 27 of the eastern third of the state, I saw that the crops are in many stages of growth, and that although some of the crop yellowing is due to salinity and/or water-logged soil conditions, a lot of it is lack of N that still probably has to be applied.

After a tour June 27 of the eastern third of the state, I saw that the crops are in many stages of growth, and that although some of the crop yellowing is due to salinity and/or water-logged soil conditions, a lot of it is lack of N that still probably has to be applied.

Another observation is the streaky nature of yellowing, especially in wheat (in the field as a whole, not an individual plant). Although I did come across a field in the Northwood area that obvious had major applicator plugging problems, most of the yellowing was about combine width, suggesting that the chaff behind the combine was tying up N.

Wheat- Top-dressing with urea/NBPT or stream-bar UAN or something similar may result in yield increases until jointing. After that stage, the effect of N application on yield is small and approaches zero at anthesis. Top-dressing also may increase wheat protein, but depending on growing conditions, any possible protein increase may be supplanted by a yield increase. The best method and timing for protein increase is the use of 30 lb N/acre as UAN or urea solution using flat-fan nozzles, the cool of the day (AM), immediately after anthesis. Later timing will decrease protein increase so that when the kernels begin to appear milky all benefit of the application is lost.

Barley- much barley I saw was in the boot stage, and unless the crop is destined for the feed market, the use of any N and/or S after this period would go into protein, which is not desirable for the malting contract. So keep the applicator at home.

Corn- In 400 miles of travel through the eastern third of ND yesterday I saw only two really good corn fields. Some corn is 3-4 leaf, and others are approaching 10 leaves. Side dress with ammonia is still possible on smaller corn, if the soil condition allows. The coulter-UAN applicators are being effectively used in these wet conditions in the SE part of the state where side-dress ammonia is often impossible due to wet high-clay soils. Application of urea over the top in small corn (less than 6-leaf) is also possible at any reasonable N rate. After the corn reaches 10 leaf, rates of urea should be restricted to 60 lb/acre to avoid too much accumulation of urea in the whirl. The N application in taller corn at higher rates should be made using drop nozzles between each row. The cheap and effective version of this is a hose coming off the boom, connected to a short pipe with the stainless-steel orifice assembly at the bottom. In our region, this homemade system is equally effective to the more expensive, but remarkably well-marketed y-drops. Both systems will provide excellent N to corn/sunflower unless it stops raining until September.

Dave Franzen

Extension Soil Specialist

701-799-2565

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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