Clayton Robins knows something about fighting soil salinity. His farm, located near Rivers, Man., sits on top of what he’s described as “starry night” soil, speckled with white pockets of high salt content.
It’s an issue he says has largely disappeared since he first added a secondary NS simultaneous crop focused on soil management rather than straight profit five years ago.
A beef producer, former Agriculture and Agri-Food Canada beef and forage researcher and 2013 Nuffield Canada agricultural scholar, Robins was the main speaker at the Manitoba Forage and Grassland Association grazing club workshop Mar. 1 in Brandon.
“The fundamental problem now is that we have degraded soils,” Michael Thiele, club co-ordinator, said. “They don’t produce like they used to and now we’re simply propping them up with higher rates of fertilizer and chemical, not realizing that’s just an indicator of the problem. The solution is to realize that our soils are degraded and figure out ways to rebuild our soils.”
Internationally, cover crops have been pitched as a way to mitigate erosion or increase organic matter in soils by maintaining controlled growth when a cash crop has been removed or forage growth has dropped.
The resulting root system, Robins says, can minimize standing surface water and draw salts deeper in the soil, decreasing salinity. Implications also exist for nutrient cycling and water retention with increased organic matter over a period of years, he said.
Those benefits may be magnified when livestock are added to the equation, keeping the cover crop in a high-growth state while recouping input costs through grazing, often in late season when perennial forages enter their resting period, Robins said.
“Keep it simple,” he said. “Start small and keep your mixes very simple and just see how it’s working for you, and then you can learn from your experiences on your own land and then either expand on it in terms of more complex mixes or different acres or for different reasons. It’s really about finding the match to what you’re doing already and how you can add it in, in a beneficial way.”
Successful cover crop species will vary widely from farm to farm, Robins noted, depending on farm climate, logistics and the underlying goal of the cover crop.
For Jordan Bos, a beef producer out of Rapid City, cover crops were an attempt to bolster performance of 220 acres of grazing land.
“The main point of going into them was just kind of to repair some of our worn-out pastures, our perennial pastures, so we thought we’d use cover crops to build up the soil,” he said. “Obviously, eliminating the standing pasture that was there was a bit of a challenge, and getting stuff to grow and that, but it actually turned out really good.”
Bos plans to continue cover cropping the parcel for several years before shifting it back to pasture.
Another workshop attendee, Heida Simundsson, hoped to explore cover crops on her Arborg operation.
“I’m an organic grower and I just started. Cover crops (are) an important part of an organic system, so I wanted to learn more about them,” she said.
While an advocate of the practice, Robins also expounded on the risks of cover cropping.
Input costs, he said, might be “very hampering.”
“It’s probably very hard to get any kind of decent cover crop in the ground for less than $30-$40 an acre, so there’s a fairly significant investment there and if you’re not capturing that investment with something like grazing and animal performance, then it is a cash outlet,” he said.
With cash crop integration, Manitoba’s short growing season may not allow a secondary seeding. Alternately, Robins said, a cover crop may be planted simultaneously with cash crops or initially seeded alone in spring, to be later replaced with a fall seeding of winter wheat or fall rye.
Crop rotation may come into play if, for instance, peas are planted as a cover crop, only to appear as a cash crop the next year, he said. Also certain cover crops may be vectors for diseases or pests, such as clubroot, and some cover crop species may become invasive if not managed.
“A lot of your grasses are likely fairly safe in most cases and the only time you’d probably have some risk with them is if there’s excessive fertility in the soil and there was a nitrate issue or something like that. Grasses are generally quite safe,” he said. “Some of the other, less traditional, species you can run into, especially the broadleafs, can accumulate a lot of nitrate very quickly and that can be a risk to a grazing animal.
“There’s always the risk they don’t establish. You’ve paid for all that seed and they don’t establish or they don’t establish to give you the volume to do what you want in terms of benefit, especially if grazing is a goal.”
The risk of nitrate accumulation was driven home for one attending farmer last year. Brian English, a beef producer from Rivers, lost a cow in late November 2016 due to nitrate poisoning.
English had tried his hand at cover cropping after a spring 2016 grazing school in Lenore, Man., eventually committing 62 acres.
“I looked at running polycrops and grazing sort of like a waste of material. I thought the cattle would probably stomp too much into the ground and then someone said to me, ‘You’re not just feeding the cattle, you’re feeding the organisms in the soil as well,’” he said.
Following the loss to his herd last year, English says he will likely remove the offending turnips from his cover crops, but he is not abandoning the practice. He plans to expand cover cropping to 138 acres this year.