Can charred wood help Nova Scotia farmers — and the climate?

In a rolling field in the Annapolis Valley, the soil in one row of grapevines is littered with charred fragments of wood.

Those unassuming bits of charred material don't look like much, but the charcoal-like substance is a tool that scientists and farmers hope will turn waste into a tool to improve the health of the soil and store carbon long term.

"Instead of losing everything in the atmosphere, we can stick … that carbon in the soil," said Vicky Lévesque, research scientist with Agriculture and Agri-Food Canada in Kentville.

Lévesque's work is just one of the projects underway as scientists and companies in Nova Scotia explore how a material called biochar can be used and produced in the province. She says it's an opportunity to support growers while fighting climate change. 

Biochar can improve water and nutrient retention in soil 

Lévesque is testing biochar on grapevines at 11 sites in the Valley to see how it affects carbon sequestration, soil biodiversity, plant growth and nutrient leaching. The experiment will run for four years.

"Talking with the grape industry, [they] see some issues in their vineyards, such as soil compaction, nitrogen loss and also water retention, and so we … brought that idea to test biochar in their vineyards."

Biochar is made by heating organic materials — usually wood, but also crop waste, manure and even sewage — to temperatures as high as 1,000 C. That process, known as pyrolysis, happens without oxygen, meaning materials don't burn, but transform to a gas and a material that's almost entirely solid carbon.

That material is thought to benefit soil in a number of ways. 

Biochar is packed with tiny pores. Those pores provide habitat for beneficial microorganisms; a tablespoon of biochar can have as much surface area as a football field.

Biochar also retains water — as much as 27 grams per gram of biochar, allowing it to hold and release water over time — and aerates soils, helping roots penetrate.

Atlantic Canada's freeze-thaw cycle causes soils to lose nitrogen from fertilizers to the atmosphere, costing farmers money and producing greenhouse gas emissions. Experiments suggest that biochar is able to retain that nitrogen, reducing emissions and fertilizer use. 

Biochar is almost 90 per cent carbon, as roasting without oxygen prevents the carbon in the wood from being released into the atmosphere.

Soils in Atlantic Canada now lose half a tonne of carbon a year, mainly through tillage. Biochar could help reverse that.

Dalhousie assistant professor Sonil Nanda, who is researching the production and use of biochar in applications ranging from agriculture to medicine, said biochar can help Canada make progress on climate change goals, especially when using material that would otherwise go to waste. 

"Canada can be a leader in tapping into these underutilized residues that come from the agricultural sector, forestry sector, municipal solid waste, forest fire wood," he said. "Biochar is one of those integral components … that will help us move towards net zero."

Lévesque said one current barrier to adoption is the cost — the experiment is using 10 tonnes of biochar per hectare, which adds up to about $10,000. Another is the availability of biochar, as there are currently no large-scale producers in Atlantic Canada. 

A Halifax-based company is working to address that. 

Sawmills in the province currently have no destination for their residual wood, the remaining material left after usable lumber is cut, due to the closure of Northern Pulp. 

If that material is left to rot or is burned in an open fire, "that is at risk of going back into the form of CO2 after the tree worked for 50 or 100 years to make it into carbon," said Don LeBlanc, president of RDA Atlantic Inc.

He said the buildup of giant piles of wood chips and shavings at sawmills in Atlantic Canada "is not a great environmental circumstance."

Instead, RDA is proposing to turn that material into biochar.

RDA has been working with a reactor design developed and patented in Poland; that reactor, which can weigh up to 40 tonnes, produces biochar in large amounts. RDA is trying to bring the technology to North America, and LeBlanc said they're currently in discussions with a sawmill in Nova Scotia to install a reactor to produce biochar. 

In the meantime, RDA is selling biochar that's produced in Poland locally, as a way of generating awareness among the public in this province. 

"As the market builds for the product, then we'll be in a better position to justify the construction of the first production facility in Atlantic Canada," said LeBlanc.

Biochar is also emerging as a solution to dead wood and other vegetation being produced by climate change. 

Joe Lewis, co-founder of the company BioBurn Pros, didn't intend to start producing biochar. His company started in 2023 to help individuals and communities get rid of piles of vegetation created by natural disasters. 

BioBurn Pros offers a way to deal with the waste wood produced by hurricanes and wildfires, using portable burners that can be towed or trucked to a site, and quickly reduce the wood to ash and biochar.

"It wasn't until we found this business model that made sense and we started pursuing it that we started to learn, oh, one of our byproducts is actually, you know, a valuable resource itself," Lewis said.

Lewis said the company is seeing growing interest in biochar, and is investigating a burner design that is specifically aimed at producing more biochar than their existing model. In the future, Lewis envisions producing biochar as part of disaster preparedness, when communities are taking steps like removing vegetation to prevent wildfires. 

"These communities then need to deal with all the residual from that project, [and] we can give back to the community all the residual char so they can use it at home."

One Nova Scotian is already using biochar at home.

Rick Ketcheson grew up on a farm in Saskatchewan, but spent his career as an engineer. When he retired, he became interested in soil health and sustainable agriculture.

For the past nine years, he's been producing biochar in a kiln at his property in Annapolis Royal, using waste wood from a sawmill nearby, and putting the material in his garden. The process is labour-intensive, said Ketcheson, but the benefits are clear.

"I know that if I maintain a good microbiome and include biochar in the soil that I'm going to have healthy plants, and it works. I have some tremendous results."

When it comes to encouraging wider adoption of biochar — which the UN has said can increase soil carbon sequestration and fertility — in Nova Scotia, Ketcheson thinks a range of options can help make it a viable tool for Nova Scotians. In the meantime, he's encouraged by the increasing interest. 

"We need systems that work for small scale that people can do on their own farms or in the community … as well as mid-level and industrial-level production. So I think again it's about diversity."