It could be called the case of the mysteriously disappearing yield.
Overall, 1996 produced the highest-ever average yield for Canadian canola and the trend for yields has steadily improved thanks to new varieties and better management.
However, in recent years some growers have also reported disappointing production.
In some cases the reason was clear: insects or disease, searing heat at flowering or flooded fields.
Elsewhere the source wasn’t obvious.
Researchers at the University of Saskatchewan College of Agriculture have decided to try to identify the forces behind these yield drops.
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But the scientific sleuths’ main investigative tool isn’t a magnifying glass or bubbling laboratory, it is the survey that appears on this page.
The questions take about 15 minutes to complete, individual identities will remain confidential and the effort could shed valuable light on a troublesome trend.
Through 37 questions, student researcher Jon Barth and agricultural economics professor Ken Rosaasen hope to get a better understanding of today’s production methods and how they influence yield.
“We are going to see if there are links between the reported yield factors, and if there has been a significant decline in yield, what are significant changes they’ve made in rotations, if any,” said Rosaasen.
For example, do producers who don’t fertilize with sulfur have consistently lower yields? What effect do rotation lengths have and do Polish varieties have consistently lower yields or production problems than Argentine varieties, he asked.
Rosaasen wasn’t able to say when the survey project will be done, but the results will be published in The Western Producer.
In 1995-96, Agriculture Canada, and the Saskatchewan Canola Growers Association attempted to survey canola growers about yield problems. There were few responses but of those who did answer indicated their problems seemed to occur at or near the flowering and early seed development stages.
Stewart Brandt, a crop input agronomist at Agriculture Canada’s Scott, Sask. research farm, believes the survey and his own observations show that fields that appear healthy sometimes produce disappointing yields because of shrivelled or missing pods.
“I’d zero in on rotations and possible insect problems.”
The big increase in canola acres in the early 1990s might be connected to the problem, he said.
“When you look at the acreage figures in areas where the problems seem to be most serious, it is obvious they are not following a four-year rotation. Some of the areas had 35 percent of seeded acreage in canola so you have to be seeding (canola one year in every three).”
One problem could be root maggot.
Tony Zatylny, crop production co-ordinator with the Canola Council of Canada, said another problem might be the difficulty in keeping up with a changing spectrum of pests.
Over the years, problem weeds have shifted from wild oats to perennial and cleavers. Flea beetle problems were replaced by plagues of diamondback moths, Bertha army worms and root maggots. Seedling disease has been replaced by sclerotinia, black leg and alternaria.
