Betting on Biochar: Can it hatch a climate solution?

Pierre-Luc Chagnon knows there is lots to learn about how biochar could help mitigate greenhouse gas (GHG) emissions for Canadian agriculture. He’s digging into the impact of adding biochar to the soil to help manage nutrient release from poultry manure in small scale field and greenhouse trials. It’s early days for his biochar research, but the Agriculture and Agri-Food Canada soil scientist is encouraged by what he’s finding.

Biochar covers a broad category and refers to material developed through pyrolysis – a process that involves exposing biological material (wood, manure, etc.) to high temperatures for a short period of time in the absence of oxygen. The properties of the resulting biochar vary greatly depending on what the base material is.

Chagnon chose biochar made from wood chips because of its sponge-like properties that he expects will help with nutrient release, and he can source it from a Quebec supplier near the Saint-Jean-sur-Richelieu Research Development Centre where he is based in QC.

“Biochar derived from wood doesn’t provide any nutrients to crops, but acts as carbon storage and may also limit nutrient losses to the environment so those nutrients are available to the crop the next year,” he says.

Soaking up nutrients for slow release

There are two main objectives for his project that build on the absorbative nature of biochar to soak up nutrients and bring a slow nutrient release quality to manure applications. Wood biochar contains many small pores that are able to retain nutrients, and each part of the reach Chagnon’s research is also looking at the ability of biochar to reduce GHG emissions.

“We know that if we meet crop requirements for nitrogen when applying poultry manure fertilizer, we tend to have a surplus of phosphorus,” says Chagnon. “Adding biochar to the soil could be a helpful tool to buffer these surpluses and distribute nutrients throughout the season as the plant needs them.”

The second part of his project is looking at ways to address the high cost of biochar as there are very few, if any, commercial operations available in Canada to make it a cost-effective additive for producers. “We are mixing smaller amounts of biochar with poultry manure that’s been through a biodigester to see if we can “load” the biochar with nutrients and detect benefits of biochar even at lower application rates,” says Chagnon.

During the summer of 2024, Chagnon and his team added biochar to field lettuce – a major crop in areas of Quebec that’s grown on heavy clay soil. They were examining if biochar had the potential to immobilize nutrient surpluses from manure and decrease GHG emissions. The data hasn’t all been analyzed data, but have some initial results on the impact on yield.

“We didn’t see any impact on crop yield,” says Chagnon. “There was a possibility that wood-based biochar – that is very rich in carbon – could rob the soil of nitrogen, but we didn’t see any decrease in yields and that’s good news.”  They also didn’t see yield increases but they weren’t expecting any short-term bumps in yield.

Chagnon is looking forward to the analysis of greenhouse gas emissions on this field trial – one that they plan to replicate with wheat during the 2025 growing season.

For the wheat trial, they’ll be measuring if biochar can help maintain better soil structure by comparing the amount of fungi in the lower layers of the soil based on biochar application rates. Fungi are a measure of soil health but excess compaction impacts the ability of fungi to get enough oxygen to help maintain soil structure. “We know biochar can play a positive role on soil structure, reducing soil density and compaction on our heavy soils.”

Studying the impact on soil health

Chagnon and his team are also working on indoor, growth chamber work at AAFC’s Ste-Clodilde experimental farm to combine varying amounts of wood biochar with biodigested poultry manure to measure the impact on GHG emissions and nutrient leaching. This part of the research is focused more on soil health as they aren’t growing crops in the growth chambers.

“This small-scale system is more convenient to work with and gives us the opportunity to focus on nutrients that are part of the solutions – and get an accurate measure of what the biochar and biodigestate are adding to the soil without the threat of big rain events,” says Chagnon. “We don’t really have an idea how soil responds to biochar and manure.”

The bigger biochar view on sustainability

Chagnon’s project is just scratching the surface on biochar, and gathering enough data to make farm-level recommendations requires long-term work. He’d love to look at the chemical diversity of biochar – and the distinct attributes depending on what it is made from.

“There is no such thing as one biochar,” says Chagnon. “I want to try more local projects where we have our own pyrolysis furnaces to see if we can generate distinct biochar and predict its impact on soil, crops and GHG emissions, based on its particular chemistry.”

In the future, Chagnon sees a time when there is enough credible science to understand the benefits of biochar, that producers could gain credits for using biochar because of the positive impact on soil health and sustainability.

“There are many sustainability benefits to biochar, and in my opinion, these should ultimately be shared as a societal cost because of the service provided beyond the benefit to farmers,” says Chagnon.

This research is funded by the Canadian Poultry Research Council as part of the Poultry Science Cluster which is supported by Agriculture and Agri-Food Canada as part of the Sustainable Canadian Agricultural Partnership, a federal-provincial-territorial initiative. Additional funding was received from Éleveurs de volailles due Québec and Airex-Énergie.