Flax has become a rarer sight in Manitoba — covering only 85,000 acres last year, down from 125,000 in 2015 — but Rachel Evans, extension agronomist with the Flax Council of Canada, hopes more agronomic knowledge will help reverse that trend.
Flax Council of Canada agronomy trials are now in their third year at sites ranging from the Kelburn Research Farm near Winnipeg, to Melita in the far southwest corner of the province and Arborg to the north.
Plots compared factors such as planting depth, planting date, row spacing, seed treatment, use of fungicides and herbicides, and interaction with stubble. Each site includes an “ideal” plot, which combines estimated best management practices, as well as a line of plots each missing only one “ideal” factor so the yield effect of that practice can be measured.
Ideal plots were seeded into cereal or pulse stubble, fertilized to a 45-bushel-per-acre yield target, used seed treatment, seeded before the May long weekend at a 45-pound-per-acre rate, less than an inch deep, and sprayed with herbicide and fungicide as necessary.
“Some of those are validated and some of those are not,” Evans said.
Four planting dates, three seeding depths, three seeding rates and two row spacings are being put to the test at the Westman Agricultural Diversification Organization site near Melita this year and highlighted during a July 25 field tour.
Data from previous years found that flax was not susceptible to planting date within the first three weeks of May, although crops planted after that time showed yield decline up to 20 per cent.
Evans noted, however, that early seeding may act as a buffer against bad weather in the fall as flax is a late-maturing crop.
The project has also shown surprising results in seedling survival, with a 75-80 per cent survival rate this year.
“Right now, if you look at the Manitoba government website for growing flax, we’re assuming (a) 50-60 per cent seedling survival and I think that we still do see those numbers sometimes, but when we have very good growing conditions that are conducive for emergence, we can see higher,” Evans said. “I think that, like other agronomy factors, there always comes a time where I think it’s important to re-evaluate and look at repeating some of that previous research that we’ve done to reassess if it’s still valuable or still valid.”
Evans advised producers to take 1,000 kernel weight and per cent germination into account when choosing seeding rate.
“In terms of deciding about seedling survival on a farmer’s particular field, I would still suggest starting at that 60 per cent when you’re doing that seeding rate calculation and then go from there,” she said, noting that the above-average seedling survival in her own trials is an observation and has not been validated by other research at this point.
Seed treatment increased plant stand numbers, although effect on yield is yet to be validated, and deeper-seeded flax took longer to emerge.
“That makes sense because flax is small seeded,” Evans said.
Evans estimates that a 22-bushel-per-acre target yield will remove 15 pounds of phosphorus per acre throughout the season, a number that increases to 29 pounds in a 42-bushel-per-acre crop. Flax will remove similar amounts of potassium at 22 bushels per acre, increasing to 25 pounds at 42 bushels per acre.
A reliance on early-season phosphorus underpins recommendations that flax be grown after a cereal or pulse, both of which also encourage the mycorrhizal fungi colonies that help flax access the nutrient after seeding. Other crops, such as canola, cause fungi to go dormant and may stunt flax the following year.
Flax is also a heavy nitrogen user, Evans said. Using the International Plant Nutrition Institute web calculator, Evans estimated that a 22-bushel-per-acre flax crop will remove 55 pounds of nitrogen per acre, while a 42-bushel-per-acre crop will remove 105 pounds.