Every spring the peat protesters emerge from their winter hideouts to advocate against the use of peat moss, so this year I'm going to beat the rush and take a deeper dive into the subject of peat moss and the question of its sustainability.
I initially hoped to have some clearcut points to present, but after a few days of grinding my way through peat moss publications, I was starting to feel quite "bogged" down by all of the peatland statistics I had to sift through. I was especially overwhelmed with the challenge of determining what each fact or figure actually meant, and deciding which information was worth noting and which could be set aside.
My view on peat moss in vegetable growing swayed throughout the research process, but eventually I circled back to where I started, now just better educated on the subject and more resolved about my current position. If you've been waffling about whether or not you can justify the use of peat moss, I hope this post will help you with your decision.
A Little Background on Peat Moss
Peat moss is a type of organic material that has been used in the horticulture industry since the 1960's. It is made up of partially decomposed plant material that has accumulated in bogs and wetlands over thousands of years. The material is primarily composed of sphagnum moss, but may also contain other plant material such as leaves, twigs, and roots.
The properties of peat moss make it ideal as a component in potting mixes. It has a high water holding capacity, which helps potting mixes retain moisture and prevents plants from drying out. It also has a high porosity, which allows for good air circulation, promoting healthy root growth.
Peat moss is harvested from natural peatlands occurring across the globe and covering over 4 million square kilometres of land area on Earth. While that amounts to less than 3% of our land area, those peatlands store about twice as much carbon as all of the world's forests combined. In fact, 1 square metre of peatland can contain 5 times the amount of carbon as 1 square metre of tropical rainforest. This is possible because peatlands can be several metres deep. This large amount of organic matter has accumulated very slowly over thousands of years as plants continue to grow and die on the surface. In most areas, dead organic matter quickly decays on the surface of the soil thanks to the presence of oxygen, but since peatlands are soaked with water, there is little oxygen available below the surface so the organic matter from dead plants is very slow to decay. It just piles up.
I'm not going to attempt to cover all of the details about Canada's peatlands because there are better sources out there, such as this wonderful story map created by Wildlife Conservation Society Canada. If you are curious to learn more about this subject, this story map will explain why peatlands are such an important part of the carbon cycle and biodiversity.
The use of peatland has gained more attention in recent years along with increased pressure to respond to causes of climate change. That seems fitting as peatlands are estimated to store abound 30% of the world's carbon stock. Carbon is released from peatlands naturally all the time as organic matter slowly decomposes in the swampy anaerobic conditions, but the release of carbon is accelerated when peatlands are drained for various reasons or harvested for commercial use. Thankfully, the awareness of peatland's carbon sequestering ability has spurred on tighter regulations and restrictions in the peat moss industry to protect this resource.
About 25% of the world's peatland carbon is accounted for in Canada, where peatlands cover 1.1 million square kilometres or roughly 12% of the country's land area. The map below gives you an idea of where all of that peatland is located. Most is concentrated in the red and pink areas.
For a more complex and interactive map of Canada's peat reserves check out the link below.
If you are curious to see the peatland distribution around the world, check out the maps on this page: https://peatlands.org/peatlands/where-can-peatlands-be-found/
How sustainable is the peat moss industry?
The answer to this can vary dramatically depending on which region of the world you are considering, and that seems to be one of the main reasons for the different perspectives on whether or not peat moss should have a place on the shelves at your local garden centre.
In Europe the peat moss story is one of rampant exploitation. It is difficult to provide an exact percentage of peatlands that have been harvested or impacted in Europe, as the extent of peatland degradation and extraction varies greatly between countries and regions. However, it is estimated that approximately two-thirds of Europe's original peatlands have been damaged or destroyed due to activities such as peat extraction, drainage for agriculture, forestry, and urban development.
According to the European Environment Agency, about 35% of Europe's peatlands are currently under some form of management, and many of these are being harvested for peat. The agency also reports that peatland degradation and extraction in Europe is responsible for a significant amount of greenhouse gas emissions, with estimates suggesting that up to 5% of Europe's total greenhouse gas emissions are due to peatland degradation and exploitation.
While some countries have implemented regulations to limit or prohibit peat extraction, peatland degradation and exploitation continues to be a significant environmental concern in Europe. Efforts are underway to restore damaged peatlands and promote sustainable alternatives to peat-based growing media, but rates of peat consumption are largely impacted by its use as a heating fuel as well. Finland, for example, is using peat at a rate of 1700kg per person, which far exceeds what one would consider using as growing media for their garden.
In Canada, the story is significantly different. We started with a much more vast supply of natural peatland here and its use is not as widespread. Ed Bloodnick of ProMix reports that "of Canada’s 113.6 million hectares (ha), less than 0.03% has been or is currently used for horticultural peat production (29,750 ha). In 2015, out of the 29,750-ha total footprint, 58% was currently under production and 25% has been restored or reclaimed. The area that still needs to be restored accounted for 15% of the total footprint, while 2% has been converted to other land use (mostly agriculture). If you consider the total peatland area where sphagnum peat moss continually grows and the amount of area that is harvested for peat moss, Canadian sphagnum peat moss growth far exceeds the rate of harvest."
One of the criticisms of peatland harvesting is that a peatland will never be able to be restored to its original conditions, but studies on this subject have shown promise.
Research has shown that after a 10 year period following peatland restoration:
"Sphagnum moss coverage well established after 5 years
Growth rate of the Sphagnum moss on the restored site is comparable to a pristine peatland or higher (which varies from 235 to 310 g/m2 depending on the sphagnum moss community) "
Biodiversity of birds, insects and amphibians in some cases higher that natural peatlands but generally on a trajectory to achieve biodiversity functionality."
Hydrological response is close but not fully in line with natural peatland hydrology.
Site’s ability to capture carbon can return to a level the same as a pristine peatland site after a period of 10 to 15 years."
It appears as though our peatland resources in Canada are in relatively good shape at the moment, but let's move on and consider if there might still be some simple alternatives to peat moss that we could switch to easily.
Are peat alternatives more sustainable?
The first alternative to peat moss that I often see recommended is coconut coir, and the argument that usually surges to the top in favour of coconut coir is that it is a waste product of the coconut industry. We're naturally wired to assume that it's good to make use of anything that was previously considered waste. However, if we start buying coconut coir, we have to acknowledge that we are encouraging the entire coconut industry by making it more profitable. If we think about what it takes to get coconut coir to our doorstep, it starts to fail miserably in any contest of sustainability. The closest coconut plantation to Canada would be found in Mexico, but since the industry is dominated by production in Indonesia, the Philipines, and India, it's most likely that a coconut coir product would travel much further. The global shipping of this product alone is a dealbreaker for me. That's before we even consider the environmental, economic, and social sustainability of the actual coconut plantations themselves.
As with many challenges of sustainability, I believe it is best to obtain our resources as locally as possible, even if the resources are not perfectly sustainable, and that's not just for the sake of strengthening our local economy. When I support a local industry, it also becomes more accountable to me. If the Canadian peat industry operates with standards that harm the natural environment or force workers into less than adequate living situations, I am likely to hear about it. If I send my money overseas to support a coconut plantation, any environmental or social cost of that industry is entirely removed from my awareness. So much of the degradation of our environment today is happening beyond our awareness and I believe more people would be willing to make different lifestyle choices if those impacts of those choices were always played out in their own backyard.
Before we leave this subject, I will mention that coconut coir isn't the only alternative worth considering. In regions with more limited peat moss availability, people are exploring alternatives more seriously. If you find yourself in one of these regions, you might find this document helpful in demonstrating some success with peat-free horticulture.
Bigger Fish to Fry
Repeatedly, as I scrolled through the research on this subject, it became clear that the impact of my annual bag of Canadian peat moss just wasn't that big of a deal in the grand scheme of things. If we look at the big picture of peatland disturbances around the world, we see that the use of peat moss for growing media only accounts for 2000 square kilometres, or 0.05% of the global peatland area.
Pie Chart Source: https://peatlands.org/assets/uploads/2019/10/srpm2019finalforprint.pdf
Data from this pie chart originated here: https://edepot.wur.nl/117602
I'm not sharing this data to diminish the impact of my choice to purchase peat moss. The impact of my purchasing decisions are still a part of the global area of peatland disturbance. What this data does is give me a better perspective though, and it seems like there are more pressing areas on which to focus my attention, areas where the changes I make could be more impactful.
If you are living a typical North American lifestyle, then chances are good that, like me, you've got some bigger fish to fry in terms of your environmental impact. For example,
this study shows CO₂ emissions of 5 lbs for every cubic foot of peat moss that is harvested, packaged, and shipped to market. That's about the same amount of emissions as burning just 1 litre of gasoline, without even including the emissions for the acquisition and processing of that gasoline before you put it in your vehicle. The average vehicle in Canada travels 11 km per litre of gasoline it uses. So every time I avoid using a gasoline vehicle for 11 km, I reduce my CO₂ output by 5 lbs, the same amount as bringing 1 cubic foot of peat moss to market. That 11 km distance happens to be about the same length as a trip to my local garden centre and back, so if I bike there instead of taking a motor vehicle, I've just avoided the same amount of CO₂ emissions as 1 cubic foot of peat moss. A simple comparison like this makes it obvious that I should be addressing some other decisions in my life before I stress out about my peat moss usage, so that's what I've been working on.
Since 2015, I've committed to producing all of our vegetables by bike, and I see no reason why that effort shouldn't continue, but the transportation of our vegetables and growing equipment is not the only energy demand on our urban homestead.
Two other energy hogs in our operation are our large cooler and grow lights. I haven't managed to measure our cooler's energy consumption directly yet, but with some heat loss calculations and air conditioner efficiency data I can estimate that our cooler size needs about 500kWh of energy per year to maintain its consistent 4ºC temperature. I also know that our local power plant burns coal and typical coal burning efficiencies would put our emissions for that 500kWh of electricity at around 1130 lbs of CO₂.
Our 4 banks of grow lights also use quite a bit of energy. When they are all turned on, they consume 0.8 kilowatts and I'd estimate that our consumption for seed starting each spring would be around 400kWh of energy, and that means creating another 900 pounds of CO₂ emissions.
With this knowledge of our energy consumption, we can now do a little comparison. If I use a full 4 cubic foot bale of peat moss in one season, that would lead to roughly 20 lbs of CO₂ emissions and if I also continue to use grow lights to start my seeds indoors and refrigeration to cool our family's food on a year-round basis, I would create another 2000 lbs of CO₂ emissions. It becomes obvious that the problem I need to work on first is my direct energy consumption. By this measure, the impact of my electricity usage is 100 times greater than my bale of peat moss!
This is why our family has started to address our environmental impact by investing in a solar photovoltaic system shown here, and it's also why my recent focus has been on decreasing our cooling energy with more efficient technology as shown here.
Every step we make in the right direction counts. The peat moss item just hasn't risen to the top of my priorities yet, and I feel I should solve the most impactful problems first, so that's the path I will continue down for the time being. If you feel the need to express your dissatisfaction with my use of Canadian peat moss, you can send your comments to complaints@vegetableacademy.com. No, just kidding. That email account doesn't exist. Do feel free to send me a message, but please also send a message to your provincial and federal government officials to express your dissatisfaction that 0.03% of Canada's peatlands are being used for horticulture. While you're writing your letter, be sure to note that at least 12,200 km² of these peatlands (far more than 10%) have already been lost to agriculture conversion and other human disturbances, and encourage your leaders to devote their conservation efforts proportionally.
Sources
Here are some of the most notable sources I referenced during the writing of this post in no particular order.
Story Map of Peatland in Canada
Protecting Northern Peatlands: A Vital Cost-Effective Approach to Curbing Canada's Climate Impact
Canada's Sphagnum Peat Moss Industry Social Responsibility
Peatlands and Climate Change
Peat Deposits Store More Carbon Than Trees
The Underappreciated Potential of Peatlands in Global Climate Change Mitigation Strategies
Strategy for Responsible Peatland Management
Peat-Free Horticulture Success Stories
Peat Moss Production and Sustainability in Canada
CO₂ Emissions From Actively Extracted Peatlands
Comparison of Canadian Peat to European Peat
Peat Resources of Canada
A Carbon Footprint for the Peat and Substrate Industry
A Typical Case Against Canadian Peat
https://www.greenhousegrower.com/production/media/the-peat-report-a-case-against-canadian-peat-moss/
A Typical Case Defending Canadian Peat
Global Guidelines for Peatland Rewetting and Restoration
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