Canola School: Second-guessing that “safe” rate of seed-placed fertilizer

“We’ve always done it that way” isn’t always the best approach in farming, and that includes the decision on how much fertilizer to put down with canola at seeding.

Canola is sensitive to fertilizer toxicity, especially in dry soil conditions.

It’s well worth revisiting what’s traditionally been considered a safe rate in the seed row, suggests Jason Voogt of Field 2 Field Agronomy in this Canola School video.

For this episode we visit a field near Haywood, Manitoba where the farmer is comparing three rates of seed-placed fertilizer as part of a larger research project organized by the Manitoba Canola Growers Association.

Farmers participating in the Canola Growers’ project were asked to simply apply what they would consider to be a standard rate for 200 feet while seeding, then shut off their fertilizer for the next 200 feet, followed by a high 1.5x rate for the final 200 feet in the same pass.

For example, the field in the video was seeded with a single disk drill applying 120 lb/acre of a common nitrogen-phosphorus-sulfur blend (13-33-0-15) as its standard treatment. The 1.5x treatment area received 180 pounds per acre.

“I expected some response, but what I saw was pretty lights-out,” says Voogt, referring to plant stand counts done at the 3 to 4 leaf stage (see photos below).

“When we did plant counts, we definitely lost a lot of plants in that one and a half x treatment. When you looked at it visually, it still looked like you had a decent stand. Even with the standard treatment, it looked okay, but as soon as you had no fertilizer at all, it was very dramatic — much, much better emergence, and more even emergence, as well.”

Standard (1x) rate of seed-placed fertilizer (photos courtesy Jason Voogt)

1.5x rate

No seed-placed fertilizer

While acknowledging dry conditions were a factor, the results have him wondering if “safe” rates are too high, and whether fertilizer toxicity causes more damage than originally thought.

It might mean equipment changes or different fertilizer timing and rates, but reducing the stress of fertilizer toxicity should also help canola seed and seedlings through other early-season stressors, such as flea beetles, notes Voogt. “Anything we can do to lessen that stress on the crop, to get it out of the ground more evenly — and more uniform — is just going to help us out.”

Check out the video above for more discussion on seed-placed fertilizer rates, the corresponding plant stand counts and uniformity, and different things to consider when it comes to meeting a canola crop’s nutrient needs.

Related Canola School videos:

Establishing nitrogen response and efficiency curves

Fertilizer toxicity may cause seedling death in dry conditions

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