Who’s testing agronomic truths of the past?

About 100 years ago when I was in ag college, it seemed that western Canadian agronomy had largely been figured out. The textbooks and lectures didn’t leave much room for ambiguity. These days, despite many more years of research, very little seems certain.

Doing soil tests before deciding upon fertilizer rates has long been a standard recommendation. But now there are different soil test laboratories conducting somewhat different analysis and often providing different recommendations.

My previous soil tests had always indicated a significant deficiency in phosphate. This year’s soil tests, through a different agronomic service, said phosphate is largely adequate, but potash should generate a yield response. Which recommendation is correct? Who should I believe?

In an age where variable rate applications can be made with extreme accuracy, agreement is often lacking on the basics. And this is with well-meaning, reputable experts, not those peddling miracle cures.

Speaking of miracle products, more options are being promoted to farmers than ever before. Some have value in certain circumstances; many are iffy. It’s become the Wild West as producers try to sort fact from fiction.

Even from reputable sources, we sometimes receive well-intentioned advice that doesn’t work as well in practice as it does in theory. A case in point is seeding by thousand seed weight rather than pounds per acre.

The Canola Council of Canada recommends producers target a canola stand of 50 to 80 plants per sq. metre or roughly five to eight plants per sq. foot — a rather wide target. To do this, you need to know the thousand seed weight and you need to make an assumption on seed emergence.

Let’s say you target six plants per sq. foot and you assume an emergence rate of 60 percent. When the thousand seed weight is four grams (small seed) this would require a seeding rate of just 3.8 pounds per acre. When the seed is larger with a thousand seed weight of six grams, the seeding rate would have to be 5.8 lb. per acre to achieve the same plant density.

According to the canola council, the average seed survival rate is between 50 and 60 percent, but it could also be 40 or 70 percent. How many producers seeding canola this spring had a nasty surprise on emergence? And how many had patchy emergence?

So while thousand seed weight deserves attention, we need to realize that it can be quickly trumped by factors outside our control.

This may be heresy, but I’d like to have the option of buying canola seed without seed treatment, just like the choice I have with other crops. This year, many producers were forced to make foliar insecticide applications to control flea beetles. The seed treatment wasn’t adequate to ward off the hungry insects.

Some observers believe canola would germinate more quickly if the seed wasn’t coated in a treatment. If we often have to spray for flea beetles anyway, why not forego a seed treatment, particularly if untreated seed can establish more rapidly? At least, producers should have the choice of untreated seed, which would significantly reduce the initial cost.

Is anyone testing the agronomics and economics of treated versus untreated canola seed?

It’s healthy to challenge the agronomic certainties of past decades. Biological systems are extremely complicated.

Unfortunately, farmers are often left wondering what and who to believe.

About the author


Stories from our other publications