Wheat School: Understanding nutrient uptake for higher-yielding winter wheat


Crop scientists know a lot more about nutrient uptake in corn and soybean than winter wheat. That’s something RealAgriculture agronomist Peter Johnson and a host of researchers, technicians and industry stakeholders have been working to change.

On this episode of the Wheat School, Johnson shares data from a new wheat study on nutrient uptake and how growers can use the results to fine-tune fertilizer application for winter wheat. Over three years (2019-2021), Johnson and collaborators ran trials at three sites in Ontario using five cultivars and two nitrogen rates. Trials were also conducted with and without T3 fungicide.

In this video, Johnson and host Bernard Tobin look at key insights gleaned for managing four key macronutrients โ€” nitrogen, phosphorus, potassium and sulfur.

When it comes to nitrogen, Johnson was surprised by the speed of N uptake by the plant. “We have 35 pounds of nitrogen already in the wheat crop at the beginning of stem elongation,” says Johnson. “That’s a big number. And what it tells us is that we can’t short the wheat crop for nitrogen early.”

The data also reveals that the wheat plant takes up 50 per cent of its nitrogen by 2nd node; 70 per cent by flag leaf and 85 per cent by anthesis. How can growers use this date to strategically apply N? See the video below for more on nitrogen and phosphorus as well as Johnson’s takeaways for potassium and sulfur. More below:

Johnson stresses growers have to manage lodging, “but if we don’t have enough nitrogen up front, we are going to starve that crop through its rapid uptake phase. So the Big Shot really does have to be prior to May 1, and in some areas by April 20 or April 15, if we can get across the ground.” That also means growers can shave back those later N applications, he adds.

The story of phosphorus uptake is much different, especially when it comes to the speed and pace of plant uptake. For years Johnson has been preaching the need for putting phosphorus down in the fall the wheat seed, but the research reveals a straight line for uptake throughout the growing season, with the plant taking up P all the way to maturity.

When it comes to phosphorus application more work needs to be done, but Johnsons wonders if “we shouldn’t look at phosphorus application in the spring to see if we can support that uptake and maybe push yields a little higher, or at least make the grain a little higher in phosphorus concentration.”

Click here for more Wheat School videos.

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