It depends.
That’s the answer to questions about what kind of nitrogen gets best results in canola, wheat and barley, according to recent studies.
Alberta Agriculture agronomy specialist Ross McKenzie is in the fifth year of a five-year study on nitrogen fertilizer trials that compare the urea, ESN and urea-ESN blended forms of nitrogen when they are banded in fall, side banded at seeding or seed placed during seeding.
Trials are underway at six sites this year: Lethbridge, Bow Island, High River, Vegreville, Westlock and the Peace River region.
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McKenzie said studies show nitrogen that is side or mid-row banded during seeding is the best option, but the form of nitrogen selected depends on soil moisture and temperature.
Fall applications are often successful in southern Alberta, he said, but there is potential for losses of more than 10 percent of the nitrogen over the winter.
“It’s a good option, banding anhydrous ammonia or urea or even ESN in late fall … (but) recognize that you might lose five or 10 percent between fall and spring.
“Most times you’re not going to get much more loss than that, but if conditions happen to be very wet in the spring, like they were last year, you run into higher losses.”
McKenzie said he does not recommend using 28-0-0 in fall because it is subject to more leaching and nitrification in wet spring conditions.
ESN, which is a polymer-coated urea, may yield better results in a wet spring, although its release will be slowed in cool conditions.
Urea has higher potential for leaching if it rains heavily after seeding, but it is also cheaper than ESN, which is an important consideration, McKenzie said.
“In many cases, having that urea release fairly quickly may not be a bad thing because between May 1 and the middle of June is when probably 70 percent of that N is going to be taken up by the plant.”
McKenzie does not recommend in-crop applications of nitrogen in cereals because yield is set at the tillering stage, and nitrogen applications after that will not improve yield.
Volatilization may also affect in-crop nitrogen’s ability to improve protein content, particularly if applied at the flag leaf stage or later.
“You would need 30 to 40 pounds to have an impact on protein at the flag leaf stage.”
Canola is a different story. In-crop nitrogen applications of about 30 lb. per acre streamed onto the soil can increase branching and flowering and raise yields.
Fertigation might be a good option with canola because the water will carry the nitrogen to soil level, where the plants can absorb it.
McKenzie said regardless of the crop, many farmers make a common error.
“In my opinion, probably still most farmers tend to under-fertilize for nitrogen,” he said. “You want to put your money where it’s going to give you the best value,” and that value is likely in nitrogen fertilizer.
