A researcher at Laurentian University’s Living with Lakes Centre is planting the seeds for a more sustainable and environmentally friendly land reclamation process.
Jonathan Lavigne has partnered with Collège Boréal to explore the potential for pulp and paper mill waste and municipal biosolids as an alternative to the lime and fertilizer method of treating soils damaged by years of acid rain deposition.
He is tracking more than 3,000 seedlings at the college’s state-of-the-art greenhouse facility to determine how they respond to nine different soil treatments as part of the first phase of his project.
His goal is to find the safest and most effective way to reintroduce organic matter to the region’s most damaged landscapes, including aggregate pits and Sudbury’s upland environments.
“Part of my master’s research project was to see how well Sudbury was doing in its regreening efforts,” said Lavigne, a former hockey player who went on to receive a bachelor’s degree in environmental science from Laurentian University.
“They were trying to reintroduce a bunch of species other than Red Pine and Jack Pine to Sudbury’s most damaged hills. My job was to see what works and what doesn’t – we tracked 1,800 seedlings over two summers, and in the end, I produced a report that I gave to the city.”
The results of the project were not surprising.
“As we suspected, only the most drought-tolerant species (essentially conifers) had a chance of reaching maturity. The rest succumbed to drought,” he said.
This is because Sudbury’s upland soils lack a key component retained by undamaged landscapes – soil organic matter.
“Undamaged landscapes have a thin, but critical layer of organic soil that helps retain moisture and critical nutrients while reducing soil temperature,” said Lavigne.
“Years of acid rain deposition caused millions of tonnes of upland soil to erode into surrounding lowlands.”
“If you look at Sudbury’s landscape, you can see that the areas with the highest elevation are the areas with the most rock concentration,” said Lavigne.
“We’ve regreened the lowlands – and they are doing very well because everything flows to the lowlands, and they are full of moisture. The uplands are really the next frontier of Sudbury’s regreening project.”
Lavigne’s PhD project will focus on improving soil for land reclamation in aggregate pits using different kinds of waste. The project will happen in multiple phases.
The goal of the first phase is to narrow down the safest and most effective soil treatments during the greenhouse trial.
“We wanted to see if we could replace the lime and fertilizer method of treating soil because the current method can be environmentally destructive and it’s really expensive to bring lime all the way over here from the prairies,” said Lavigne.
“Using different types of waste, we’re trying to see if we can replace this old method with a new method and find a solution that’s a bit more local.”
Lavigne has partnered with different businesses and organizations to get his hands on a number of different waste materials that would otherwise get landfilled or burned.
Using these materials, he developed the nine different soil treatments currently under trial.
These include Sudbury’s traditional method of treating damaged soils with dolomitic limestone and fertilizer in addition to treated municipal sewage, boiler ash, and pulp and paper mill waste.
“Our control is just regular gravel material that you would find in an aggregate pit. If we were to plant or lay seed down without doing anything, it would go onto this material,” he said.
“The second treatment is stockpile soil.”
When building an aggregate pit, Lavigne explained, companies remove about 10 to 20 cm of the top layer of soil.
“Then, they stockpile it and pile it back on after the project is finished, but sometimes after 20 years, the material isn’t good anymore,” he said.
“What they will often do is cycle the soil – they will take material from aggregate pit two and use it to regreen aggregate pit one. They are always borrowing from another place to cover somewhere else. It’s a bit destructive, and it’s not very environmentally friendly.”
Lavigne is also using a material called biomass boiler ash.
“That’s the fancy name for it. In a pulp and paper mill, they burn up a lot of material, and biomass boiler ash is literally just the kind of ash from the tree bark that they get rid of,” he said.
“They use this material all the time in the Ottawa Valley region because it’s really high in calcium, and it’s good for calcium depleted regions. We’re using that ash plus some agricultural fertilizer because the ash isn’t very high in macronutrients.”
He is also using pulp and paper mill waste mixed with healthy forest soil from another location, and municipal sewage powder mixed with lime and fertilizer.
Many of these materials have been used for decades in agricultural fields and mine tailings where all the effluent is accounted for. They have not been considered safe for use on public lands.
“The material back then was bad for business. You did not want that near any type of public waterway or anything like that,” said Lavigne.
“I would say probably in the last 10 to 15 years, there’s been a lot of advancements in pulp chemical engineering and processing. Now, there’s been enough technological advancement in terms of treating this stuff that it could be considered safe.”
The greenhouse trial will test all these treatments for efficacy.
When Lavigne has narrowed his selection down to two or three treatments, he will then use those treatments to try and regreen an abandoned aggregate pit in the region.
“During the greenhouse trial, what we’re doing is using this controlled environment where we can see if any ugly, nasty chemistry is coming out of the water, and we will see at the end of the trial what is most effective,” he said.
“Because even if one pulp does really well, there’s no point in doing a larger trial if it’s just going to damage the waterways because they’ve been through hell and back already.”
Lavigne added that there’s a huge difference between taking a bit of material and putting it in a lab and actually applying that material in a field environment.
“The lab and field are two different realities – a lab is a controlled environment where you know all the variables and the field is a chaotic system. You put the material down and you don’t know what will happen after that,” he said.
The second phase of the trial will involve applying the chosen treatments to an aggregate pit that was abandoned in the 1980s and planting trees and a variety of other plants to see how well they take.
“We’re going to let that grow for two to three years and then we’re going to see at the end what material did well and what we can find being leached out of that site,” he said.
“The idea is that if we can regreen a gravel pit using this material and we can say it’s safe, then we can apply this protocol to similar environments like the 70,000 hectares of land in Sudbury that still need to be treated.”
Lavigne and his team completed a pre-application site assessment for the next step of the project in September.
“The goal is to lay down the material sometime this fall, and then to plant in the spring. We will track them from spring 2022 to around fall 2024,” he said.
This research will have important implications as the world enters the UN Decade on Ecosystem Restoration in 2021, Lavigne added.
“When you’re trying to reclaim a landscape anywhere in the world, one of the biggest issues is being able to improve the conditions of the soil,” he said.
“The soil needs to be able to support a seedling for at least the first few years of its life where it’s at its most vulnerable. If it isn’t able to do that, you’re going to plant 300 trees and six of them are going to survive.”
The results of this experiment, he added, will be “another tool” in a restoration ecologist’s pocket.
“Sudbury really is the poster child for how a community can come together to successfully claim an environment,” he said.
“With over 200,000 brownfield/industrially contaminated sites in Canada alone, the world needs the forward-thinking, innovative science coming out of Laurentian's natural science departments to lead the effort in tackling climate change and restoring damaged landscapes.”
The Local Journalism Initiative is made possible through funding from the federal government.
sud.editorial@sunmedia.ca
Twitter: @SudburyStar
Colleen Romaniuk, Local Journalism Initiative Reporter, The Sudbury Star
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