Cover crop capabilities – producer knowledge helpful for beef producers

Forage cover crops are annual or biennial plants that farmers seed, often in mixes, in order to “cover” the soil. Also known as cocktail crops or polycrops, producers often seed these blends to accomplish goals like increasing production, reducing evaporation, improving soil biology, providing pollination opportunities, increasing natural nutrient cycling, and providing forage. As with any practice that gains momentum quickly and offers so much promise, there are risks and rewards.

Kevin Elmy, Saltcoats, Saskatchewan

Kevin Elmy is an experienced and accomplished cover cropper, and has been experimenting with different species to improve soil health on his family farm, Friendly Acres Seed Farm, since 2009. “We heard about [cover crops] in the U.S. and I thought I would try using tillage radish to see what would happen,” Elmy says. “I started using more diverse blends and here we are today,” he says.

He works to design blends for himself and customers that meet field-specific criteria. “Species selection has to be related to goals,” Elmy maintains. When dealing with fields that have variable topography, such as potholes and hill tops, he says seed blends have to be diverse to reflect these different areas.

Elmy likes a diverse species mix so that some plants are in a vegetative stage at any given time, benefiting soil health. “Vegetative plants feed soil biology through root exudates,” Elmy explains, and adds that producers should consider using a diversity of functional plant groups as well. “Oats, barley, wheat, triticale, rye are all one functional group,” he says. These cereals are often known as cool-season, or C3, species. Producers may also want to add warm-season species (i.e. C4 species), like corn or millet, which flourish later in summer in warm, dry conditions. Other functional groups like broadleaf species, forbs, or legumes, can also be added to the mix. “But first, set goals. It makes species selection and management much easier when you know what you want to do.” Elmy times his seeding operations according to species selection. “Warm-season plants need to have warm soil and warm nights to grow rapidly. Blends high in C4 plants need to be seeded later than C3 plants,” he reasons.

Top tips

• Elmy says weeds are a symptom of a soil problem, in many cases free nitrate in the soil. If producers are planning on using a cover crop for grazing or haying, management may be simple. “Time it so the weeds do not go to seed. It may change your plan, but will fix the problem.”

• Problems with seeding depth can be a common element of failure so to minimize dilemmas, Elmy has a strategy. “We design blends so seed sizes are similar or use species that are forgiving at the wrong depth.”.

Jillian Bainard, PhD Agriculture and Agri-Food Canada

Swift Current Research and Development Centre, Sask.

Jillian Bainard, PhD, is a research scientist who is working to understand how forage cover crops grow in semi-arid Saskatchewan. She’s looking at whether these crops do what they are professed to do, including studying whether they improve soil in a measurable way, and whether producers can reduce inputs through cover cropping. Bainard presented her work during a recent BCRC webinar.

She has many ongoing projects including a collaborative study evaluating the impact that cattle have when they are introduced into a forage cover crop. She’s studying the potential impact that cattle manure and urea has on soil fertility as well as whether trampling or compaction has a positive or negative affect on various soil physical characteristics. The study also has an economic component as it investigates integrated crop-livestock systems.

When asked about species selection, she says it can vary depending on how much time and effort producers want to put into seeding a crop. A labour-intensive solution might be to seed different crops in different zones of varying topography or soils, however a mixture is more practical. “The goal of a more diverse crop mix is that a farmer might have more of a buffer against crop failure in difficult areas,” she says.

Seeding a mix of crops with a variety of seed sizes can be difficult because different plant species should be seeded at different depths. “Seeding options will depend on the type of equipment at your disposal,” Bainard says. “Some farmers use the fertilizer side-bander to seed at different depths – run the smaller seeds together at a shallow depth and the larger seeds together at a deeper setting,” she explains. “Another option is to do multiple passes, although obviously this is a nuisance,” Bainard says. “I have also seen some interesting “homemade” equipment built for intercropping,” she notes.

For most of her research trials, different seeding options were not feasible.

“We seed everything together in a combined mix at an intermediate depth of around three quarters of an inch to one inch deep (2-2.5cm),” she says. “This is a bit shallow for the large-seeded crops, and a bit deep for the small-seeded crops, but we’ve had pretty good success at getting everything to grow,” she explains.

Establishing a cover crop is largely weather dependent and needs to balance out the end use.

“You’ll be looking for good soil moisture, but of course you need to consider your end goal. If you want lateseason forage, seeding later will be a good option,” she says. “For farmers that want to graze a cover crops, they would have to anticipate when the crops will be at peak biomass and where this fits into their grazing rotation,” she adds.

Bainard has had mixed experiences with weeds and forage cover crops.

“In some trials, I have documented weed reduction in the mixture plots compared with the monocultures,” she says. “I have also seen what happens when forage cover crops do not establish well and get overrun by weeds,” she explains, adding that herbicide control is usually not an option because most mixes have both broad leaf and cereal species. “I think there is a lot of promise for using crops like brassicas to help control weeds,” Bainard says, adding that brassicas have strong above-ground competition. They also have the potential for allelopathy, which means their root system potentially gives off toxins that inhibit other plant growth.

Top tip

• Producers may want to start by choosing a simple mix likely to grow well in their region. “Picking a mix that is moderate in the number of species and complexity will reduce the amount of potential issues and troubleshooting that you might have to do,” she adds.

• Caution is advised with potential cover crop species that could become weedy. “For example, hairy vetch is often labelled as an annual, but can act more like a biennial and will re-grow the following year,” Bainard says. This may lead to an unwanted situation in the future.

• Bainard says it’s helpful to be adaptable. “If something isn’t working, be ready to use the cover crop in a way you weren’t necessarily intending to – maybe instead of grazing a crop you have to bale it, or maybe you can’t use it for feed and have to treat it as a plough-down, and hope that there are other benefits for your soil in the long run,” she says.

Producers and scientists alike are still navigating when and how to incorporate cover crops in real world situations.

There are many considerations with cover crops, from species selection to how to get the seed in the ground, however the practice shows great potential and is making a big impact on many farms across Canada.See also: www.beefresearch.ca/factsheet. cfm/assessing-the-impact-of-grazing-annual-foragecover -crops-in-an-integrated-crop-livestock-system284