The learning curve of cover crops

Cover crops may have an almost endless number of combinations, but end goals, planting windows and seed costs may help narrow down species selection

It’s not enough to convince producers to give cover crops a shot — there needs to be a game plan.

There are plenty of reasons why. Seed can be expensive, especially if there’s no livestock to help recoup that cost through their digestive systems. Many worry the fall seeding window is too narrow to give the crop time to amount to anything, but admit they’ve few alternative planting dates to consider.

In some cases experts like Lee Briese, of North Dakota’s Centrol Inc., say farmers gave cover crops a shot years ago, and abandoned the practice when it didn’t work that year.

Lee Briese of Centrol Inc. discusses the advice he gives cover croppers in North Dakota during the Getting the Most Out of Every Acre event in Brandon in November.
photo: Alexis Stockford

A more deliberate approach will shift most of those arguments, Briese says. Many of those unsuccessful cover crops may have been the wrong species mix, planted at the wrong time, or did not have an end goal firmly in mind during the planning stage.

Why it matters: Cover crops can help a farmer accomplish many things, but understanding the end goal is key to the management choices.

“Species selection is critically important,” he said. “So that’s the first question for me. If you’re planting a warm-season cover crop a little too late, it’s not going to do well. If you’re planting a cool-season cover crop in the heat of the summer, it’s not going to do well.”

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The end goal will also be central to species selection, plant timing and seeding rate, he added. A mix tailored to fight erosion will look very different from one planned to fight weeds, increase farm resiliency or improve soil health, he noted.

[AUDIO ABOVE] Joe Gardiner of Clearwater, Man., talks to Alexis Stockford about how he got started with cover crops, what keeps him coming back to the practice and how he’s changing up his farm management this year.

Local experts like Yvonne Lawley of the University of Manitoba have echoed the point. Lawley has urged producers to consider the root profile of their cover crop, whether the mix leans to warm or cool season, whether those species fix or scavenge nitrogen, and how they plan to terminate the crop so they are not creating their own weed problem.

The entire process is more art than science, she said, and will be highly individual to a farmer’s circumstance, equipment, work flow and end goals.

A balanced diet

Cover crops have grown incredibly complex on some farms, Briese noted, with some producers putting down something like 30 different species. That’s great for biodiversity, he said, but significantly less so to the producer’s pocketbook.

Briese advocates the “five food groups” philosophy, which he says ensures a diverse species mix while potentially balancing seed cost. A balanced cover crop mix includes cool-season grasses, warm-season grasses, both warm- and cool-season broadleafs, and legumes, he said, and the addition of both warm- and cool-season crops helps ensure that something will grow out of the mix, regardless of weather conditions.

A mix of more than five species may start to see diminishing returns on the balance sheet, he noted, particularly for producers just starting out with cover crops.

It’s a good strategy, according to Michael Thiele, co-ordinator of Manitoba’s Ducks Unlimited grazing club and an outspoken advocate of cover crops as a tool for biodiversity.

“I think that’s simply practical, but think of that: five species versus what has been one for 100 years,” he said.

Michael Thiele is among the local experts urging producers to take up cover crops, but also to have a distinct plan before they plant.
photo: Alexis Stockford

Joe Gardiner of Clearwater is one of the producers who, self-admittedly, “goes crazy,” with his mixes. His cover crops run up to 15 species, which he ties to his goals of maximum biodiversity and biomass both for the sake of soil health and forage for his cattle.

At the same time, he noted, his full-season cover crops mitigate the risk of taking on more species compared to an underseeded or post-harvest mix. Farmers who aren’t doing that are wise to consider less complex mixes, he said.

“That makes a lot of sense for a relay crop or a fall-seeded cover, because you’re just not getting the return from the biomass to justify the seed cost, and I get that totally and I understand it,” he said. “From a full-season cover perspective, the goal is to stimulate biology. You cannot stimulate biology with a monoculture.”

Joe Gardiner of Clearwater outlines his cover cropping system during an event in Brandon last month.
photo: Alexis Stockford

Gardiner also sources much of his seed on his own farm, further reducing cost. His cattle also make that risk more palatable, he acknowledged. He first got into cover crops as a means to increase fall forage.

The triangle

Kevin Elmy, manager of Cover Crops Canada and a cover crops consultant with Imperial Seed, has a slightly different approach.

Many producers interested in cover crops forget to add in rotation, he said, particularly when it comes to something like tillage radish.

Tillage radish is a well-known compaction buster in the cover crop world. Manitoba experts, however, have recently raised concern that the brassica might create a bridge for pests like flea beetles and disease, given the local popularity of canola.

It’s one reason that Elmy has brought sugar beets into his Imperial Seed mixes. Although more expensive, the beets also fill much the same niche as tillage radish.

“I have a triangle, so it is grass, legume, broadleaf,” he said. “If you’re looking from a grass to a brassica (in the rotation), which one are you missing? You’re missing a legume, so you want to try and introduce something like subterranean clover or Persian clover.”

Kevin Elmy, of Cover Crops Canada, says rotational considerations are too often forgotten.
photo: Friendly Acre Seed Farms

That short legume would be underseeded as a relay crop, but remain under the canopy until the cash crop is harvested and then grow through the fall, he said.

That system depends on an early seed date, he noted, giving the legume time to bloom and set nitrogen.

The system is a harder sell for producers without livestock, he acknowledged, but argued that a cover crop that knocks back weeds, saves a fall desiccation, or over the course of years, increases water infiltration and saves a producer from having to install tile drainage, will more than pay for itself.

“Once we set goals, then we can pick species, then we can have a strategy on how to get it done,” he said.

Weed pressure

Soil health advocates may have biodiversity and soil structure top of mind, but Briese says many of his customers are turning to cover crops as weed control, after nothing else has worked.

In some cases, he noted, those producers are attempting to choke out a herbicide-resistant weed — a growing concern in both his home North Dakota and Manitoba — he said a properly managed cover crop blend may be less expensive than a herbicide pass.

“They’re realizing that this is a potential opportunity for them. It’s not incredibly expensive if done well,” he said.

Once again, he noted, the goal will underscore the plan of attack. He pointed to one of his clients fighting herbicide-resistant kochia. As such, that customer actually needed his cover crop to overwinter to provide that early-season competition.

Anyone planning for weed control will want to pick species that establish quickly with good ground cover, Lawley advised.

“The other thing that’s really important to think about for that criteria is which weeds do you need to suppress and what is the biology of when those weeds are growing or establishing themselves,” she said.

In the case of a winter annual, she noted, the producer will want a vibrant cover crop post-harvest to interrupt the weed’s life cycle.

Salinity

Cover crops fighting salinity, meanwhile, should get in the soil as early in the season as possible, Lawley noted.

“Even your cover crops may not establish where it turns white. You need to work on shrinking that white area by getting a cover crop established in that wet area immediately around it,” she said.

In many cases, that cover crop will be broadcast rather than drilling in what is essentially patch seeding, she noted. As such, Lawley advised producers to choose a small-seeded crop or an easily germinated option like barley.

Barley may be among the most common saline-tolerant options, but Lawley argued that there are enough other options for a multi-species cover crop. Sugar beets, camelina and sorghum sudan grass “to a certain extent,” may also thrive, she said.

Putting in the effort

Work flow is a challenge, cover crop experts admit, although Lawley pointed out that fall seeding might be done in the morning if a farmer has to wait until the drier afternoon to combine anyway.

Fall seeding is often the easiest to work into a year, Gardiner said, but added that it is also the seeding window most likely to end in failure, since there is little growing time left in the season.

For both Thiele and Briese, the key is both a realistic starting point and commitment.

“Cover cropping is a skill and we need to learn it, no different than you would learn to play an instrument,” Briese said. “You can’t play Bach right away. You learn ‘Twinkle, Twinkle Little Star’ first.”

Both Thiele and Briese urge producers to choose a limited number of acres to start, band then attack that cover crop with the best plan possible.

“Look, if you’re really serious and you’re committed, take a field and commit to that field for five years,” Thiele said. “You’re not going to see the world change in one or two or three years. You need to be committed to this and do it right and be focused and committed and, in five years, you’ll convince yourself that these systems can work.”

About the author

Reporter

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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