The fall objectives: Make sure the chopper can spread the width of the cut. Have a chaff spreader to avoid the thick harrow-immoveable mat of chaff right behind the combine. Cut higher so more of the residue is standing stubble. If necessary, harrow the crop on a hot windy day.
This is the no-till approach to residue management.
Unfortunately, it doesn’t always work out as planned, leaving a challenging residue situation in the spring. Perhaps surprisingly, after decades of no-till advancements, good seed placement in heavy residue can still be a challenge.
The Alberta Crop Industry Development Fund (ACIDF) acknowledges this in a priorities report: “Having seen the benefits of reduced, minimum or zero tillage, most Alberta farmers aren’t looking to go back. Still, as many expressed at the ACIDF Cropping Initiatives Issues and Solutions Sessions, these new-school farming systems need a rethink in terms of residue management.”
Craig Shaw, who farms at Lacombe and is on the ACIDF board, has “gone back” — at least for his canola land. He tried residue managers to clear a path for his seeder openers. He tried vertical discs. Results were okay, but not great. “So we went back to tillage ahead of canola,” he says. “This is not the solution that those of us who are strong believers in no till wanted, but canola benefits so much from good placement in warm soil.”
What can we do for no tillers at heart who just have too much residue?
In theory, a “residue manager” that can sweep away residue ahead of the drill opener would take the pressure off residue management in the fall. It would eliminate the need for a spring tillage pass, which adds cost, eats up valuable time in the seeding window and can spread clubroot and verticillium. And the residue-free area of black soil would warm up faster than residue-covered soil outside the strip.
Based on Shaw’s experience, residue managers fall down in high-residue situations. The spoke-wheel units he tried had rigid mounts that could be fixed for light, medium or aggressive.
“Under normal residue load, they worked fine,” he says. “But even when set for aggressive, they didn’t work in big piles of straw or chaff.” This is a problem because that’s when you need them to work best.
Floating models are available, Shaw says, which would probably be an improvement, but the other issue is row spacing. “In narrow rows, you can’t move a lot of residue before you start piling it up on other rows,” he says.
So Shaw tried paired wavy coulters as ground-blackeners in front of each opener. “They are not the end-all answer either because in heavy straw they just ride over top,” he says.
“They are better than nothing, but in terms of blackening a strip in front of each row, we weren’t confident we were accomplishing that goal,” he says.
He would like to see more research in this area, but as an individual farmer, he asks, “How much money do I spend on this?”
“With our little experience, we never got to the point where we felt we had the right answer.”
In the 2000s, researchers with Alberta’s AgTech Centre (now called the Farm Stewardship Centre) studied various residue managers suited to narrow row spacing. Brands tested were Brummelhuis, K-Hart, Siemens, Terra-Tine and Yetter. While they often provided some benefit, improvement over the check with no residue manager was hit and miss.
“In some cases, residue managers did allow direct seeding in residue situations where going with the opener alone would not work at all,” says Blaine Metzger, one of the study leads. But the AgTech Centre’s January 2007 report concluded: “Residue managers and wheels are viable options for use with hoe and disk openers while seeding barley, canola, peas or wheat, but significant differences in crop emergence and yield occur infrequently.”
Another idea is strip tillage. Unlike a residue manager, which skims above the soil surface, strip tillers blacken a band of soil to turn in residue and improve moisture infiltration. They can also apply fertilizer. Ground outside each strip is untouched, making it a conservation tillage compromise. Seeder openers, with the help of accurate GPS guidance, go down the middle of each strip.
Strip tillage is gaining popularity for row crops, particularly because many row croppers are looking for a conservation tillage option. Wide rows also leave lots of room for strips.
The University of Manitoba has several researchers looking at strip tillage for row crops.
They hope to show Manitoba corn and soybean growers how strip tillage can meet their goals for moisture and residue management and fertilizer placement while also adopting some conservation tillage.
Strips are often around eight inches wide. In one pass, the tools move residue out of the seed row, then till the strip and build a little berm — while leaving the rest of the land untouched.
With strip tillage, U of M researchers found that yields match those of fully tilled fields, and crops that need moisture in August — soybeans, for example — have more potential to find extra moisture in untilled parts of the field. Soil in the strip is also warmer, which can be important for emergence in western Canadian climates. But Yvonne Lawley, who oversees strip tillage research as assistant professor in U of M department of plant science, says the berm is the key. “If the berm is flattened, soil in the strip is not warmer,” she says.
The question of course for canola growers is: What about strip tillage for narrow-row crops?
“I think this is definitely an option for growers tilling their fields currently, though zero- or minimum-till growers may want to consider other options first. Moving from conventional to strip tillage does minimize soil disturbance as it prepares the seed bed for canola and helps minimize in-strip weeds,” says Canola Council of Canada agronomist Autumn Barnes. “On the compaction front, strip till is another way to help increase porosity without totally ripping up the entire field.”
Ken Coles, general manager at Farming Smarter in Lethbridge, leads research on narrow-row planters. “I think there is some merit to a strip tillage system like this, which is being replicated in our new precision planter project,” he says.
From Coles’ perspective, residue management is part of a bigger question: “How can we improve uniformity issues associated with canola establishment?” Taking care in the fall with higher cut heights, better chaff and straw spreading at the combine, and heavy harrowing are important steps in answering this question, as are seeding tools that follow ground contours and have independent depth control, he says.
Is strip tillage part of the answer? Can a four-inch strip on 12-inch centres work, and is the cost of precision guidance to seed into the middle of that strip worth the investment? Answering that question will come with continued precision research.
To Coles’ point, canola growers want a uniformly emerging crop of six or more plants per square foot. While seeding into a swept or tilled strip of black topsoil might help, we don’t yet have a reliable solution for narrow rows in a messy residue situation. Until then, the best approach with your current seeding tool is to slow down to improve placement and, if the insurance is necessary, you put on a couple extra seeds per square foot.