Broadcast canola: Taking the tool of last resort to task

Fields too wet to drill have led to a resurgence in questions about broadcasting canola

Manitoba’s canola growers aren’t quite ready to opt for broadcast seeding, although the province’s oilseed experts say the poor spring and lack of field access has put the topic on the table.

Why it matters: Few producers had turned a wheel coming into mid-May, leaving some to ponder if they will be forced to broadcast seed their canola this year.

Justine Cornelsen, agronomist with the Canola Council of Canada, says she hasn’t yet heard of producers desperate enough to broadcast, although the topic has come up during conversations with her fellow canola specialists.

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“We don’t feel that we’re quite there yet,” she said May 13. “Broadcasting of canola is something that you see at the end of May, beginning of June when people are feeling really crunched and, of course, on really, really wet fields.”

Some regions in Manitoba are taking longer to dry out, she noted.

Cold temperatures delayed seeding and kept producers out of the field well into May. About nine per cent of seeding was complete after the first week of May, according to the provincial crop report, compared to 20 per cent last year.

Best practices

Farmers who do decide to broadcast will have to develop a much different plan of attack than a typical spring, provincial oilseed specialist Dane Froese warned.

“I like to treat broadcast seeding canola as a tool of last resort,” he said. “If it’s possible to go on that seeder — and you have enough time to get your cereal crop in, get the peas in, start with the corn and then look at canola — definitely do favour the air drill or the air seeder over broadcast seeding.”

Froese estimated that drilled canola yields five to 10 per cent higher than broadcast-seeded fields.

Perhaps most obviously, producers who opt for a broadcast application will need a much higher seeding rate, due to seed survival.

The province estimates that 35 to 45 per cent of seed germinates in broadcast seeding, compared to 55 to 65 per cent of seed that is drilled.

Last year’s residue will also factor heavily in seed survival, Froese noted, since heavy cover will block seed and fertilizer contact with the soil and may require harrow passes to clear the seedbed or to incorporate seed and fertilizer.

The Manitoba Agricultural Services Corporation requires that broadcasted seeds be integrated into the soil before MASC seeding deadlines in order to be insurable.

Alternately, Froese said, the field may be so wet that a harrow pass is necessary in order to allow equipment for broadcasting onto it.

If residue is heavy enough to need full tillage, however, Froese urged producers to abandon broadcast seeding.

“If your ground is capable of supporting actual tillage, it would very likely support a traditional air seeder and that would be your better option,” he said.

Fertilizer application will also be different, the agronomist warned.

Producers will have to double their phosphorus rates if they hope to see the normal “pop-up” benefit of early-season phosphorus, he said.

The Canola Council of Canada estimates that farmers must apply two to four times the amount of broadcast phosphorus to equal the yield response of seed-placed or banded fertilizer.

At the same time, Froese warned, those high phosphorus rates come with toxicity concerns if producers are blending seed and fertilizer.

While phosphorus is critical for early-season growth, canola is also more susceptible to seed toxicity than more tolerant crops like wheat — leading agronomists to urge producers with low phosphorus tests to build soil levels during cereal years in their rotation.

Industry recommendations generally set safe levels of seed-placed phosphorus at 20 pounds per acre (although Froese notes that under ideal moisture conditions, like much of the province is seeing this spring, those levels might be bumped).

“Do consider the seed application rig and what that machine is capable of doing,” Froese said. “If you are blending with fertilizer and then broadcasting on in order to achieve the target rate, do blend that fertilizer just before it goes on the field. Don’t blend it and let it sit in the truck for three days because fertilizer toxicity will affect the canola.”

Nitrogen will also have to be protected, he noted, suggesting that producers consider a urea inhibitor to avoid volatilization loss.

Don’t panic

Growers may not want to panic about getting canola in the ground.

Canola seeded in the third week of May is still at full yield potential, according to yield data out of MASC, compared to cereals, soybeans, corn and peas, all of which fall below optimal yields. The oilseed also has the flattest yield decline as the season presses on, the same yield data shows.

Cornelsen pegged mid- to late May as optimal seeding for canola, although she did caution that late-seeded crops may run into harvest challenges come fall.

About the author

Reporter

Alexis Stockford

Alexis Stockford is a journalist and photographer with the Manitoba Co-operator. She previously reported with the Morden Times and was news editor of  campus newspaper, The Omega, at Thompson Rivers University in Kamloops, BC. She grew up on a mixed farm near Miami, Man.

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