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Don’t Scrimp On Canola Inputs, Study Shows

“The Ag Canada guys called this the ‘stacking benefit.’ But what it means is that you can’t get the maximum benefit out of canola if the canola is starved for all of those other inputs.”


Astudy that looked at how individual canola inputs affect yield has found that the effect of the total is greater than the sum of its parts.

An ongoing AAFC study at six direct-seeded sites across Western Canada between 2005 and 2008 compared a full package of inputs for canola in a two-year canolabarley rotation aimed at achieving the highest possible yields to a minimal input package.

The study compared open-pollinated versus hybrids, seeding rates (75 seeds per square metre versus 150), no fertilizer versus 100 per cent soil test recommendations, and no herbicide versus full application rates.

“And then they either removed an individual input from the full package, or they added an individual input to the ‘empty’ package,” said Derwin Hammond, a senior agronomy specialist with the Canola Council of Canada, in a presentation last week at the Canola College in Brandon.

“They tried to look at which inputs give us the biggest return in terms of individual inputs.”

The results send a strong message to growers who may be tempted to cut back on pricey inputs this year, he said. “There’s no one input that brings you anywhere close to what you get when you deploy all of those inputs together in an integrated fashion,” said Hammond.

In the first year, herbicide seemed to offer the biggest benefit as a single input, which was not surprising given that the sites were fairly weedy, he said.

Hybrid genetics added to the “empty package” led to a gain of four bushels on the overall yield, and higher seeding rates upped yield by one bushel. A full rate of fertilizer added seven bushels to the total per acre, while a full dose of herbicides bumped that up to nine.

“If you add up all those incremental benefits from adding a single higher rate of input, then you get a total of 21 bushels an acre. But when you look at the actual yield they got in the full input package, it was 28 bushels better than the empty package,” he said.

“The Ag Canada guys called this the ‘stacking benefit.’ But what it means is that you can’t get the maximum benefit out of canola if the canola is starved for all of those other inputs.”

The “synergies” from giving the crop every possible advantage happen because everything works together. No herbicide means losses due to weed competition, and low seeding rates waste fertilizer because there are less seedlings to mop it up.

Over time, using less herbicide had an accumulating effect on yield in succeeding years, and eventually the weed biomass gained enough momentum to overwhelm the crop and cut heavily into performance.

Farmers determined to cut corners on their canola can take heart in the fact that cutting seeding rates and halving the fertilizer had the least impact.

“When you’ve got the full package, and you’re only subtracting one nutrient or half the herbicide, those plants are still reasonably competitive and can compensate for that at least in the short term,” said Hammond.

The result from using half the recommended fertilizer rates was interesting, he noted, because the effect on yield was less than the researchers expected.

The reason, said Hammond, could be that the no-till, direct-seeding cropping strategy increased organic matter, which boosted available late-season nitrogen and which was not detected in the soil test results.

“We may be underestimating this nitrogen mineralization and how much we get from that in successive years of canola production,” he said.

Getting out the sprayer earlier in the season pays, he added, citing another study which compared the yield advantage of hitting the weeds when the canola is at the one-to two-leaf stage versus later, up until the six-to seven-leaf stage.

Even at a rock-bottom canola price of $250 per tonne, waiting too long to spray could cost a farmer up to seven bushels per acre, or $6,500 to $7,000 per half section in terms of yield lost just by delaying to the three-to five-leaf stage.

“Pretty significant economics, and really no additional cost to the producer if he’s got to spray eventually anyway,” said Hammond.

“The bottom line is that if you’re waiting for that last flush of weeds, you may have flushed quite a bit of money down the drain.”

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