Wheat School: What's the best N rate for my goal yield and protein?


How confident are you in your selected nitrogen (N) rate for wheat? Do you adjust that number based on yield potential? Variety? Soil type? How much N is enough to reach maximum potential? You might be surprised to learn that existing nitrogen rate recommendations are based off of older research, with older varieties, and without any indication as to how timing of N applications may impact both yield and protein content.

Amy Mangin, research agronomist with the department of soil science at the University of Manitoba, recently joined RealAgriculture’s Kelvin Heppner to discuss a completed two-year, multi-site research project looking at modernizing nitrogen recommendations for not just more current varieties, but also different types of spring varieties — from the high potential protein lines, to the big yielders.

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Mangin explains that the research looked at not just feeding the plant for yield, but also at where the cut-off was for trying to maximize that yield. At a certain point, the plant shifts available N into protein, this project looked at when that deadline is met — is it at stem elongation? Flag leaf? Certainly, post-anthesis, Mangin says, nitrogen applications will have no impact on final yield, but what is the optimum timing?

Perhaps one of the more interesting findings of the work was that, in 2017, for the very-high yield potential sites (over 100 bushels per acre), “even when I was applying up to 200 pounds per acre, I wasn’t necessarily applying enough nitrogen to meet those high yield goals as well as the high protein goals. Our protein was falling short, even with the really high applied nitrogen,” she says. It’s food for thought moving forward on big-bushel varieties, for sure.

Of course, max yield and max protein only matter if there’s profit left after paying for those inputs. Mangin explains that there will be a full economic analysis available in the final report, available later this spring. From a purely biological perspective, both the high-yield and high-protein varieties responded similarly, but there was certainly a difference in final protein content, and Mangin says they’re still working on working in the protein premiums to get a better sense of differences in profitability.

Hear the full discussion, below:

Farmers interested in the full report (available in April, 2018) can check the Manitoba Wheat and Barley Growers website here.

Related Wheat School: New Nitrogen Strategies Needed to Keep Up With Big Yield Potential

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