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Seed survival still stumps

Seed killer still at large. Several suspects behind high mortality, but no arrests

What’s killing those canola seeds before a seedling can get out of the ground? That could very well be a 64 million or perhaps billion dollar answer for Prairie farmers looking at seed priced at about $10 per pound and anywhere from a 20 to 50 per cent seed mortality rate. But you can’t necessarily blame seed or equipment for the poor performance.

Even with good-quality seed and properly adjusted equipment used to seed the crop into almost ideal seed bed conditions, the results of crop emergence are all over the board, says Blaine Metzger, a researcher with Alberta’s AgTech Centre in Lethbridge.

Blaine Metzger, right, and technician Joel Hubert, use this portable fan to demonstrate the variability of product distribution through an air seeding manifold.

Blaine Metzger, right, and technician Joel Hubert, use this portable fan to demonstrate the variability of product distribution through an air seeding manifold.
photo: File

The AgTech Centre has looked at the issue in the past couple of seasons, and hopes to continue the work to pinpoint what is affecting canola seed survival, says Metzger.

“The fact is there appear to be so many variables,” says Metzger. “We have used one type of opener on replicated plots to seed canola and in one plot the emergence was 80 per cent, and then used the same piece of equipment on another plot and the emergence was 50 per cent.” In fact, in their research they have used eight different openers all on the same air seeding system — from minimum to high disturbance openers — and found the same degree of variability.

This is one of the hoe-type air seeding systems evaluated for seed placement by Alberta’s AgTech Centre. Of the eight systems tested, researchers say equipment was not the issue affecting canola emergence rates.

This is one of the hoe-type air seeding systems evaluated for seed placement by Alberta’s AgTech Centre. Of the eight systems tested, researchers say equipment was not the issue affecting canola emergence rates.
photo: Alberta AgTech Centre

“You can get losses due to seeding depth and seed placement, seed that didn’t germinate because it was mechanically damaged. Fertilizer damage and seeding speed is an important factor, too” says Metzger. “But we found that losses due to any one of these factors in itself wasn’t enough to account for situations where there was 50 per cent seed mortality. It is frustrating, because just when you think you might have something, the next plot proves you wrong. So we’re thinking if it is not the seed and equipment it has to be an environmental effect.”

Metzer says he had focused on canola because it has such variable seed survival. But large-seed crops such as cereals and pulse crops can also experience 20 to 30 per cent seed mortality.

crop planter

Field research shows precision planters like this vacuum planter do a good job of seed placement but are not perfect for depth control and seed spacing.
photo: File

Tracking seed placement and depth, and counting seedlings is a labour-intensive process. Metzger needs as many as eight technicians and summer students spending a lot of time on their knees to determine where the seeds are and whether they survived.

While the AgTech Centre research has yet to crack the case of what is causing seed mortality, Centre engineers and technicians have made several observations about seeding through this project and others over the years.

Facts and mysteries about seeding

Seeding is not as straightforward as farmers and the researchers at the AgTech Centre might like. Consider these facts.

  • Even with a canola seed batch with a germination test of 99 per cent, AgTech Centre researchers achieved only 50 per cent seed survival and plants emerging in some seeded plots.
  • Mechanical damage to seed, seeding too deep, seed that is off the seed row and didn’t make proper seed-to-soil contact and fertilizer damage are all factors that can affect seed germination and emergence. But overall, these appeared to only account for about five per cent of reduced emergence.
  • Seeding speed can affect seed survival and germination. AgTech research has shown increasing travel speed from four to six miles per hour can reduce germination/emergence by 10 to 15 per cent. Slower is better.
  • The new precision planters do a pretty good job, but they aren’t perfect in terms of seed placement. The AgTech Centre compared a precision seeding system on a conventional air drill to a disc-type precision planter, also known as a vacuum planter, row crop planter or corn planter.
  • Precision planters had as much as one-half inch variability in seeding depth, compared to an older-style rigid shank opener that had as much as much as one-inch variability in seeding depth.
  • Precision planters also had their challenges with consistent seed spacing in the rows. Depending on temperature and moisture at seeding the precision planters could develop static electricity, which would hold small seed crops such as canola in the mechanism and then drop a small clump of seed in the seed row. In some plots, researchers found more clumps of seed with the vacuum planters, than with conventional air seeding system. Manufacturers are redesigning planters to reduce the risk of static electricity.
  • Looking at seed row spacing and seed bed utilization (SBU), the Centre has conducted research comparing eight-, 10- and 12-inch row spacing with a shank-type air seeding system with wide openers, to results from a seeding system with narrow disk type openers.

A five-year project showed the most consistent top yields were produced on eight-inch row spacing, with a shank-type system where seed was distributed over a four-inch spread in the seed row. Metzger’s not recommending people abandon disc type seeding systems in favor of shank-type systems. While the wider openers had higher SBU, they were also more variable in seeding depth.

About the author

Field Editor

Lee Hart

Lee Hart is editor of Cattleman’s Corner based in Calgary.

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