How cover crops have turned into a 'win-win' for P.E.I. potato farmers 

There's a lot more green in potato fields across Prince Edward Island in the months outside the traditional growing season.

That's because potato growers are turning to cover crops as a way to make their soil healthier — and generate some extra cash. 

Researchers with the P.E.I. Potato Board have been tracking the adoption level of cover crops for the last few years, and the numbers are substantial.

"The last few years we've really seen that number jump, so we're up to over 50 per cent of the acres that had potatoes in them last year had a cover crop in them from our survey," said Ryan Barrett, research and agronomy specialist for the Potato Board.

"About 50 per cent of the acres that are going into potatoes this year also had a cover crop last year. And that's a big change from what it used to be. Now, we have a lot of fields that are staying green into the fall."

Some of the cover crops, Barrett said, die off over the winter and then the field is ready for potatoes the next year. He calls it a "win-win."

"From our research, we've been able to see that there is an associated yield benefit the next year. We actually saw somewhere on a 10 per cent yield improvement," Barrett said.

"That's because the cover crop is holding nitrogen, holding nutrients over for the next year that may have previously been lost."

Healthier soil

Barrett said the cover crops also give the soil a bigger boost.

"It's building soil organic matter, it's feeding the soil microbes. It's energizing, and revving up the soil to get ready for next year," Barrett said.

"So I think having that living cover is a real benefit."

Barrett said the cover crops also reduce the amount of erosion. It holds the soil in place instead of it getting blown away during the winter.

"It takes 100 years to grow an inch of topsoil. So if we lose an inch of topsoil in two years, that's not a sustainable method of farming," Barrett said.

Some of the cover crops, such as winter wheat and winter rye, are harvested the following fall and generate additional income for the farmer, Barrett said. 

Has to make economic sense

Andrew Lawless, of Hilltop Produce, grows potatoes on farms around Kinkora. He has been following the research by the Potato Board and its partners in the Living Labs project.

"I think that really opened my eyes to the benefits, and it's awful nice to see the fields covered for the winter," Lawless said.

"Nobody likes to see brown snow banks."

Lawless said he was also interested to hear the increase in yields the researchers found when cover crops were used in potato fields.

"It's not cheap to put in cover crops. Could be anywhere from $60 to $100 an acre, even more. So there definitely has to be some return. As farmers, our margins are tight," Lawless said.

"As well, there's climate change, and we're getting more extremes, and more heavy rainfall events, and our winters are changing. It's great to be able to have them green, and a root mass to hold the ground in place."

It's great to be able to have them green, and a root mass to hold the ground in place​​​​​—Andrew Lawless, Hilltop Produce

 
Lawless said the main reason that a potato grower would not plant cover crops would be timing, if the harvest is late in the fall. 

"You have to get it done by a certain window, but there are new potato varieties that are being developed every year that are allowing us to harvest before those dates," he said. 

Multi-year cover crops

Judith Nyiraneza, an Agriculture and Agri-Food Canada research scientist, was co-lead on the cover crop research. 

While she's pleased with the results, she said the next step is to convince farmers to leave cover crops in the field for multiple years for even more benefits. 

"If you have a perennial cover crop — you have a cover crop for two years or three years — you have the above-ground biomass, but also the below-ground root biomass. That really makes a difference," Nyiraneza said.

Nyiraneza said that there are also economic benefits to multi-year cover crops.

"Growers are here to make money. That is understandable," Nyiraneza said.

"But there are also growers who understand that if a soil is healthy, you can have higher yield with your cash crop. If we say potatoes or grain, that can compensate that year where you did lose harvest."