Soil health main focus of cover-croppers

Early adopters of various farm practices often provide valuable information.

It was farmers like these that, through trial and error, perfected the zero-till system and direct seeding, for example.

But they’re all working in isolation, and maybe swapping a few ideas over the internet or at the occasional conference.

The University of Manitoba’s Yvonne Lawley wanted to know more, and she set up grad student Callum Morrison to conduct a survey of farmers who incorporate cover crops in their operations. Expectations were initially modest, but Morrison stepped up to the plate and hit a home run.

“When I started this project, I told Callum if we heard from 50 farmers I would be happy,” Lawley told this winter’s Manitoba Agronomists’ Conference. “Because of Callum’s relentless pursuit of cover croppers across every nook and cranny of the Prairies, we heard from over 528 farmers.”

That makes it the most in-depth look at the practice throughout the region through the eyes of the farmers making use of it on their farms.

The survey asked farmers how they were using cover crops, what their benefits and problems were and why they were growing them in the first place. Once collected, the surveys also showed there were farmers interested in growing cover crops but hadn’t. So, more questions were added to the survey.

“And those questions focused on what were their barriers to adoption and what will enable further cover crop use on their farms?” Lawley said. “It was fascinating to see that this interest in using plants as a tool to improve soil health is inspiring farmers across the Prairies.”

Cover crops are one of the newer ideas at this end of the North American Great Plains. It involves seeding plants into the field right after harvest and letting them grow during the shoulder season. It’s a way of getting living roots into the ground, nurturing soil biota and getting the field ready for next year’s crop. Think of it as an off-season training camp for living soil.

“So we asked a lot of questions about the agronomy of these early adopters who were growing cover crops,” Lawley said. “We also asked them why are you doing this and the most common response was focused on soils and soil health, increasing soil carbon and keeping living roots growing in the soil.”

The responses varied depending on the type of farmer. One of the side benefits of cover crops is grazing, a chance to have them pay their own freight immediately by using them as animal feed. Grain farmers, who might not see immediate financial benefit, may not be as keen.

“So when talking to different audiences about cover crops, a lot of people, especially cash grain farmers, say that’s great but that’s for the grazers. It’s not really for me,” Lawley said. “And so Callum decided to look at the respondents who indicated that they were grazing cover crops versus those who said that they weren’t.”

According to their data, just over half of cover crop growers in the survey said they intended to graze those cover crops. For a fall shoulder season crop, that would mean grazing them in the fall. A full season cover crop, grown during the following year, would be grazed at some point in the next season. Just over 40 per cent of the acres were for grazing but almost 60 per cent were not.

“So taking a look at how this splits out by cover crop type, we have a smaller percentage of the shoulder season cover crops that are intended to be grazed, whereas a larger percentage of the full season cover crops were intended to be grazed,” Lawley said.

“But one thing that really surprised me was just how many farms grew full season cover crops with no intention of grazing them and I think that’s something that I want to understand and learn more about in the future.”

Many of the early adopters said they saw agronomic benefits within three years. They reported reduced soil erosion, improved water infiltration as well as higher levels of soil organic matter and lower levels of weeds.

“These are the benefits that farmers are seeing that are motivating them to do this practice on their farm. I’m hoping to see some of these benefits in my long-term studies.”

Lawley also said since cover crop agronomy is in its infancy this far north, there are a few wrinkles to iron out. There’s no denying how short the growing season is here and that’s right at the top of the list.

Autumn in the northern Prairies also tends to be dry, so soil moisture lost through late season transpiration is another factor. Then there’s the straight up costs for buying seed along with the time and cost of planting.

“So we also asked these farmers what could we do to enable cover crop use on the Prairies,” she said. “Among the top responses related to compensation, paying for storing carbon, tax credits as well as research specific to the Prairies for cover crops.”

Perhaps this is an idea whose time has come but producers still need to know more. As crop scientists do more research and farmers do more experimenting themselves, there is a need for local networks and local farm tours to spread the knowledge.

“Callum really likes this point,” she said. “Although there are challenges, no farmer who responded to the survey said that their old system, where they were doing things without cover crops, worked better. I think that’s a strong motivating signal to continue adapting this work for the Prairies.”

— Gord Leathers is a farm and science writer based in Winnipeg. A version of this article originally appeared in the Manitoba Co-operator (May 4, 2023, page 9).