Anastasia Kubinec has a friendly reminder for canola growers at seeding time: the focus should be on the plants, not the canola seed.
“Farmers need to get out of the mind set of a standard pounds per acre rate,” said Kubinec, an oilseed specialist with Manitoba Agriculture. “They need to think about the plants per sq. foot to target in the field.”
Kubinec delivered this message to producers at the Manitoba Canola Growers Association annual meeting, held Feb. 3 in Brandon. The springtime question, Kubinec said in her presentation, needs to shift away from five lb. or six lb. or seven lb. per acre.
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Instead, the focus should be on the factors that contribute to canola plant density: soil temperature, seeding depth, seed size and weight, seeding speed and of course, rates of seeding.
The ideal plant population, she said, is 10 plants per sq. foot, but producers should shoot for a range of seven to 14 plants per sq. foot.
How to achieve that range, given all the variables, is the $64,000 question. Or depending on farm size, the $640,000 question.
One factor that’s often overlooked is variation in seed size.
“You really need to look at, from a grower’s standpoint, what’s the seed size of my seed lot when you’re plugging it into some of those equations, (which) you can use to target your plant population,” said Derwyn Hammond, agronomy specialist with the Canola Council of Canada.
Hybrids, in general, are larger than open pollinated canola seeds, Hammond said.
Since a larger seed size usually means a higher seeding weight, it’s “important for farmers to take into account the thousand seed weight of the canola seed they are planting,” Kubinec said. “And adjust the seeding rate so that the number of plants per sq. foot is still targeted.”
For instance, according to data provided by Kubinec, with a 1,000 seed weight of four grams, a seeding rate of 5.4 lb.. per acre should produce seven plants per sq. foot, assuming a 50 percent survival rate.
Jumping up in seed weight, to 4.5 grams per 1,000 seeds, it takes six lb. per acre to produce the same seven plants per sq. foot.
Another factor, which is always important, is the emphasis on seed depth.
“We did see a lot of that last year. There were a lot of seeds in at two inches,” said Kubinec, who worked for Canterra Seeds before joining Manitoba Agriculture. “That may have been a factor of (producers) going too fast and the seeder bouncing.”
The significance of consistent depth is that the temperature gradient in the soil can vary from year to year.
On May 6, 2007, from data collected at the University of Manitoba’s research farm in Carman, Man., the soil temperature at one inch was 10.82 C versus 10.45 C at two inches, a difference of 0.37 C.
On May 6, 2005, in comparison, the temperature at one inch was 11.79 C and 9.54 C at two inches, a difference of 2.25 C.
A difference of two degrees may determine if a seed emerges or not, Kubinec said.
“The longer it stays in the soil, the longer it has for bad things to happen.”
