Research project in P.E.I. potato field confirms the oldtimers were right about manure

A research scientist on Prince Edward Island has confirmed what many Island farmers knew decades ago when it was common to raise cattle and grow potatoes on the same farm: Manure is good for spuds.

So good, in fact, that a recent study showed a small amount of manure added to cover crops grown before potatoes were planted in a field increased marketable yields by 26 per cent.

Judith Nyiraneza, the study's author and a Charlottetown-based research scientist with Agriculture and Agri-Food Canada, said manure has long been known to regenerate soil and boost cover crops.

"So far, we have seen very interesting results around manure application," Nyiraneza said.

"When we apply a very low amount ... we were able to see that manure boosted yield by 26 per cent, but it did also increase the soil nitrogen supply capacity by 44 per cent."

Nyiraneza said the numbers are impressive for such a small amount of manure, around 20 metric tonnes, and she is now looking at how a wider use of the treatment could benefit the environment.

"It would be an excellent soil regenerative management practice if we can see that it does also reduce greenhouse gas, and does increase the carbon sequestration," she said.

Nyiraneza said there's been interest from potato growers in partnering with local cattle farms to source the manure, while also providing grazing land for the cows.

"There is a win-win situation where their farm is getting feed for free and the potato growers are also having manure on their land without needing to transport it."

Researchers from Agriculture and Agri-Food Canada are also testing the manure-cover crops combination to see what they do when it comes to reducing greenhouse gas emissions and carbon sequestration. (Nancy Russell/CBC)

She's working with three potato growers in a combined potato-livestock project through Living Lab — P.E.I.

"I think we are realizing that you cannot push the soil to produce more and more," she said. "Eventually you have to go back and try to regenerate it if you want to sustain the yield for your future generation."

Nyiraneza hopes to have some "interesting results" to share next year, comparing carbon sequestration between 2017 and 2024.

'Fertilizer plant'

At least one P.E.I. potato farmer has already made the move back to a combination of cattle and potatoes.

Stephen Visser and his wife purchased a feedlot late last year in Orwell Cove — leading one person they know to jokingly refer to their cattle operation as their "fertilizer plant."

Nyiraneza says many potato growers already know about the benefits of using manure. (Shane Hennessey/CBC)

Visser said they can feed culled potatos to the cattle and use the straw they grow for bedding, while the cattle provide a steady source of free manure.

"That was a pretty big deal for us because we really like the idea of putting manure back on the land," he said. "Actually, the reason why we grew cover crops is because we felt cover crops were as close to manure as we could get."

Visser said it's been several decades since he used manure on his farm; they lost their source when they stopped raising pigs in the mid-1990s.

Stephen Visser stands in front of cattle operation that he and his wife purchased late last year, in Orwell Cove, P.E.I. (Nancy Russell/CBC)

"Manure is hard to get. A lot of people that generate their own manure use their own manure; they don't generally sell it too much. We generally use cover crops as green manure, basically because we couldn't get manure," he said.

"There's fewer livestock operations than there used to be to pull manure from, so that's going to be a challenge.

"I think there's going to be a shortage if demand goes up. There won't be really enough to go around."

Livestock strategy

The P.E.I. government has tried to raise awareness around soil health, including through a 2021 campaign. The Department of Agriculture developed a livestock strategy to rebuild soil health through the production of more manure.

"It takes a long time to deplete soil organic matter, and it takes a long time to build it back up," said P.E.I. Agriculture Minister Bloyce Thompson.

"Probably one of the reasons is because... our livestock on this Island was depleted after BSE in the early 2000s, and we haven't built the herd up."

Bovine spongiform encephalopathy, also known as BSE or mad cow disease, is an incurable and often fatal disease affecting cattle. The detection of a case in an Alberta cow in 2003 led other countries to ban imports of Canadian beef, leading to a major contraction in the industry.

"We're really missing that manure and the cattle part of our ecosystem for building the soil up," Thompson said.

One person refers to Stephen Visser's feed lot as his "fertilizer plant". (Rick Gibbs/CBC)

Visser is optimistic that adding the cattle operation will pay off with healthier soil and greater potato yields. He is impressed with the results from the Agriculture Canada study.

"That's amazing. I think that's great. If that's really true, if we can prove that [on] our farm here, that would be very, very helpful here," he said.

"This will be the first year that we've done it, and we're really hoping to see good results in a good sorghum crop, and then in the long term in a better potato crop."

Visser said the manure will also serve another important purpose — preparing his farm for climate change impacts including drought and heavy rainfall.

"Climate change, it really affects us," he said. "We may not see it from year over year, but over the long term it affects us and our crops — and yeah, it's a big deal for us."