Wheat School: Updating N Recommendations for Higher Yielding Wheat


New wheat varieties being grown in parts of Western Canada have made it possible to produce yields that are off the charts, quite literally.

Much of the research supporting nitrogen rate recommendations for wheat on the prairies has been based on a top-end yield target of 65 bushels per acre.

“That was quite adequate when we were growing Barrie wheat, but we have made little public effort to update those nitrogen recommendations. And with some of the wheat varieties coming on-stream — I believe it’s like Hyola 401 entering the open-pollinated canola market — we now have genetics that is 15 to 20 percent or bushels more than that,” explains John Heard, soil fertility specialist with Manitoba Agriculture in this Wheat School episode. (continued below)

MAFRD’s John Heard discussed N management for high yield and protein wheat at the Manitoba Crop Diagnostic School in Carman last week.

Beyond 65 bu/acre, recommendations until now have often been based on the rule-of-thumb of 2.5 pounds of nitrogen per bushel, which means 80 bushel wheat needs 200 pounds of N.

“We don’t have the research to back up those nitrogen rates right now,” notes Heard.

So he’s working with the new Manitoba Wheat and Barley Growers Association and over a dozen on-farm collaborators this year to build a pool of data to support higher nitrogen rate recommendations. Higher yielding wheat will generally have lower protein content, so they’re also looking at top-dressing nitrogen later in the season to boost protein levels.

As Heard explains, their protein trials follow what he calls “the 7-10-20-30 rule”: application 7 days post-fusarium fungicide timing; 10 U.S. gallons of 28-0-0 and 10 gallons of water; spraying when temperatures are below 20 degrees C; and 30 pounds of N.

Spraying when temperatures are below 20 degrees has been a challenge this year, notes Heard, and so their research plots and fields where farmers are trying to boost protein are showing considerable leaf burn.

“We still have to learn if there has been yield loss,” he says. “And we also want to learn with farmers what our probability is of achieving a half point or a full point protein increase.”

The push for higher yields and protein will naturally come with higher risk for growers, says Heard: “We may well find that it’s too risky for some farmers to chase the high yields and high protein. They may find getting a somewhat lower yield but more sure protein, maybe that’s the wheat varieties they should be growing and managing for.”

Related: Wheat School: Top-Dressing Nitrogen to Boost Protein

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