Nitrogen Source for Wheat - Urea, 28%, Sulphur?

It’s TIME to get fired up about putting nitrogen on your wheat! But what source is best? There has been lots of discussion lately around urea and 28%, and more recently sulphur has joined the fray. So what is the real scoop?

Streamer Nozzles

Unlike most of the literature, Ontario field plot data shows a yield benefit to 28% over urea (Table 1). The main difference between Ontario trials and other jurisdictions is the fact that all our trials used streamer nozzles, not floodjet nozzles. Lesson #1 - If you don’t use streamer nozzles with 28%, don’t use 28%! 

Uniform Application

There is no good reason that 28% should outperform urea, but often it does. Our only explanation is that 28% has perfect uniformity across the sprayer boom. Miss a one foot strip, and you will see it all year! Applicators spreading urea often have difficulty in achieving perfect uniformity of distribution. Urea is less expensive than 28%. Still, Table 2 suggests that on average an $8.00/acre advantage remains for 28%, despite lower cost of urea. Lesson #2 - If you are using urea, either “double spread” with a spinner spreader (20 foot centres with a 40 foot spread, at half the rate), or be sure the airflow is working perfectly. 

Sulphur

Free sulphur from air pollution (acid rain) is declining as efforts to reduce pollution are successful. At some point we will likely need to add sulphur to our wheat crop, as they did back in the late 1800’s and early 1900’s. However, sulphur additions from pollution should still be enough to meet wheat requirements, although canola and alfalfa may run short. Sulphur must be applied in the sulphate form to be available to the crop - ammonium sulphate, potassium sulphate, or ammonium thiosulphate. We simply do not know if sulphur on wheat will pay yet. 

LESSON #3 - Do a plot with us! We are starting a three year sulphur trial, and have one year left in our 28% versus urea trial. Trials are simple to do. Contact Wheat’s Wild Warrior through the CROPLINE at 1-888-449-0937, if you are remotely interested in helping figure out the answer. Just DO IT! 

Table 1 and 2 summarize yield and economic results of the first two years of the 28% vs Urea Trial being conducted through Middlesex Soil and Crop. 

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