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Considerations for Nitrogen Applications in Spring Cereals

As the wheels have started turning and the spring cereals are going in the ground the question that continues to come up is how much nitrogen (N) should I apply? With spring cereals we know there is a balance between having enough nitrogen to maximize yield potential while avoiding lodging issues. However, OMAFRA’s current nitrogen guidelines for spring cereals are considered to be on the low side for the varieties that are available today along with our current management strategies (table 1). The current guidelines also do not take into account any potential fungicide by N interactions or the use of plant growth regulators (PGR).
 
As a result, research trials were conducted in barley, spring wheat and oats in 2014 and 2015 to determine the Maximum Economic Rate of Nitrogen (MERN) for these crops both with and without a fungicide application.  What that research found is that while there is an opportunity to push nitrogen rates further, where you are located and how you will ultimately manage the crop plays a part in what N rates should be applied.
 
Barley
 
In the trials conducted over two years in southern and eastern Ontario, there were no major yield differences between nitrogen rates when a fungicide was used versus when it wasn’t.  The MERN in southern Ontario for barley when a fungicide was used was 83 lb/ac and without a fungicide application the MERN was 80 lb/ac (Figure 1).  As we move to eastern Ontario, the nitrogen requirements for barley were much lower.  The study found that the MERN for barley without a fungicide application was 52 lb/ac while it was 57 lb/ac with a fungicide in eastern Ontario. Interestingly, the study did find a significant nitrogen by fungicide interaction in northern Ontario and much greater need to push those nitrogen rates higher.  The MERN with a fungicide was 127 lb/ac and without a fungicide the MERN is 100 lb/acre (Figure 2). The price of barley at the time of the study was $3.96/bu and nitrogen was $0.55/lb
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