Yvonne Lawley talks cover crops during Crops-A-Palooza in Carberry in July. Photo: Alexis Stockford
Article originally published on August 22, 2019 in the Manitoba Co-operator
Farmers will need more than a cursory plan to reap the benefit of cover crops in the Keystone province.
Cover crops have gained their champions in Manitoba. The practice is cited among other alternative grazing strategies like bale or swath grazing to extend the grazing season and, arguably, improve soil, according to livestock and forage organizations.
Manitoba Agriculture has also thrown support behind the practice, although the Ag Action Manitoba program funding cover crops excludes farmers grazing their own cattle.
Organizations such as the Manitoba Forage and Grassland Association commonly call on local producers who have embraced cover crops to tour their farms or speak at association-sponsored events.
One such speaker, Clayton Robins, was recently chosen for a Canadian Forage and Grassland Association study for his work grazing energy-dense cover crop forages near Rivers.
Not everyone’s cover crop experience has matched up with that success, however. Manitoba’s short growing season is a challenge, while the last few years of dry weather may have turned the tables on anyone trying to establish a cover crop.
Why it matters: Industry and government are both pushing Manitoba farmers to integrate cover crops, but not everyone has had good results if they’ve experimented rather than planned it all out.
Industry and government are both pushing Manitoba farmers to integrate cover crops, but not everyone has had good results if they’ve experimented rather than planned it all out.
Farmers should know what they want to get out of a cover crop before starting the drill, Yvonne Lawley of the University of Manitoba said.
“We’re hoping that cover crops are going to be a recipe (where) we just know what we need to follow — just give me the recipe. I’ll do it. I’ll have success on my farm — but really, cover crops are more like a game of cards where you’re being dealt a hand and you have to respond to the field, the situation and even the growing season that you have,” she said.
A farmer’s goal will take much of the guesswork out of the decisions that come next, diversification specialist James Frey of the Parkland Crop Diversification Foundation said.
“If you know that you’ve got an area that is prone to salinity, well that actually takes a lot of the questions out of choosing the right cover crop mix or when to plant it or how to terminate it because you know that your goal is salinity, specifically,” he said.
We know the problem, what’s next?
The potential seeding window should be the next thing on the table, Lawley said.
Seeding in early summer allows warm-season annuals time to grow, while farmers waiting until late summer could opt for cool-season crops and fall-seeded cover crops are best suited for winter annuals, farmers heard during Crops-A-Palooza last month in Carberry.
Farmers may plant in late May or early June if they want to dry out a wet field, Lawley said. Early-harvested crops present another obvious window, she added, although the busy harvest season might put a time crunch on planting cover crops.
“Some people do that by planting the cover crops in the morning when you can’t harvest, and others are trying to find people who can do that work for you,” she said.
Some farmers may plan a mix around legumes, with the intent to add more long-term nitrogen to the soil, while others are planting for pollinators and have the length and timing of bloom periods in mind, speakers said in Carberry.
Salinity, meanwhile, may mean more select plant options, since there is little benefit if crops don’t grow well enough to draw down the water table or outcompete weeds like kochia or foxtail barley.
Still others, who hope to graze those cover crops into the fall, will be thinking about feed values or the proportion of legumes, while those looking to build organic matter or break up compaction will weight their decision heavily towards root profiles.
Most annual field crops root between four and five feet down, according to provincial soil management specialist Marla Riekman.
“Which is shocking to a lot of people, because quite often they think that if you only have, say, three feet of above-ground height, then you only have three feet of below-ground height, but crops like wheat, canola will easily be rooting four, even five feet,” she said.
Soybeans will top out at 3-1/2 feet, she noted, pointing to their more lateral root system.
Cereals are a strong choice for building organic matter, Riekman said, pointing to their fibrous root systems.
Those fighting compaction, meanwhile, will want to include taproots to break up soil and add pores for water infiltration and future root growth.
Taproots, however, also highlight another critical variable to cover crops: rotation.
Tillage radish is a frequent go-to for compaction issues and a common component of cover crops in the U.S.
Riekman, however, is worried that brassicas like tillage radish might cause issues in Manitoba’s canola-heavy rotations. Canola was Manitoba’s largest crop last year, with 3.1 million acres harvested, according to MASC.
“Having too many brassicas in a cover crop just extends that ability for your insect and disease pressure, things like clubroot, stuff like that to spread,” Riekman said. “We actually want to break that up by expanding, widening the rotation with canola.”
Farmers may want to consider non-brassica taproots like buckwheat, sunflowers or added legumes in a cereal mix, she said.
A termination plan will be critical to avoid cover crop benefit turning into future weed challenges, Lawley also said.
A crop that winterkills may help avoid that issue for those new to cover crops, she said.
She also urged farmers to start with crops they are familiar with and are easily accessed, like cereals, to ease the process.
Not every cover crop has to be a five-species mix, speakers also said in Carberry, despite the prevalence of multi-species cover crops highlighted during the field tour circuit.
“You don’t have a lot of stuff in a cover crop in order to make it effective,” Riekman said.
The province suggests that farmers leave check strips, take soil tests or use yield monitors over time to see if the cover crops are meeting their goal.