There is a lot of talk these days about the environmental impact of using peat and peat moss in horticulture. We are told to stop using it so that we can preserve the peatlands. This sounds like the responsible thing to do but is this really a problem? Are we running out of peat? Reports seem to indicate that Europe has used up all of theirs and now Canada is starting to do the same. Is horticulture really responsible for the loss of bogs and wetlands?
If we don’t use peat or peat moss, what alternatives are there? Coir gets mentioned a lot but is it a suitable substitute? Is it a better choice, environmentally?
Much of the information about peat moss is misunderstood and it’s time to weed through the myths.
Peat – What is it?
Peat is the accumulation of partially decayed vegetation. It is found in wet areas like bogs, mires, moors and muskeg, collectively called peatlands. The water in these areas maintains an anaerobic condition which slows down decomposition to the point where it almost stops. Over time, peat accumulates. I was in Ireland recently and visited some of the areas used for harvesting peat. Unlike our Canadian peat moss, it has a dark color and shows few signs of the plant material that went into making it. Once dry it is quite hard.
Peat moss is a form of peat that is created mostly from sphagnum moss. It has excellent properties for the horticulture industry.
Global Peat Resources
Peat can be found all over the world in both temperate and tropical climates. The International Peatland Society provides a detailed spreadsheet of peat reserves on a global basis.
Here is some peat availability data for specific countries :
Bogs can be shallow or very deep and therefore it is important to know if the units being discussed are area or quantity (volume or weight). The apparent inconsistency in the above tables can be explained by the fact that peat exists in different thicknesses. Although Canada has the largest area, it does not have the largest quantity of peat.
Contrary to popular belief, we are not running out of peatlands.
Peat Usage Through the Ages
If you are reading a story about the use of peat in horticulture you might conclude that this is a modern day problem, but it’s not. Peat has been harvested in Europe for heating purpose since Roman times. European peat is a good source of heat, and is fairly clean burning.
For many years peat has been used in agriculture to improve soil and peatlands have been drained and converted to agricultural land or used for forestry.
Of the peatlands that have been used by humans, 51% has been used by agriculture; 26%, forestry; 22%, drained tropical peatlands; 1% energy and growing media (see the above pie chart). The 1% is mostly heating since this number represents use for heating over hundreds of years and horticulture for only 50 years. Horticulture only started using peat in significant amounts in the 1960s and did not became popular until the 1970s.
Of the peat that is currently harvested globally for heating and horticulture, 60% is used for heating, and 40% for horticulture.
These numbers clearly show, that horticulture has not been a significant factor in the loss of peatlands nor is it a major factor now.
Peat as a Heating Source
During my visit to Ireland was was able to see how peat is collected for heating. As you drive through the countryside, especially on the west coast, you will find piles of black material in the fields. These are bricks of peat drying in the sun. Once dry they are used to heat homes. These peatlands have been used for heating and building homes for hundreds of years and so you might expect them to be a rare sight, but they’re not. Once you know what to look for, you will find these fields all over the place.
The use of peat for heating in Ireland has now been stopped.
Peat bricks being dried in the sun.Peat is used as a heating fuel in a number of European countries. In Finland it is their main source of fuel for both homes and power generating stations. It is a common myth that they will run out of peat soon. One third of Finland is peatland and only 0.7% is used for harvesting peat. Their peat resources are 12.5% protected, 32.4% pristine, 51.2% forest, and 3.6% agriculture. Extraction for horticulture is negligible.
Are Peatlands Harvested Too Much?
There are 400 million hectares of peatland on earth and 86% remains undisturbed. Of the 14% that is disturbed, horticulture accounts for far less than 1%. Forestry and agriculture are the main reasons for peatland disturbance, with heating contributing a minor amount.
Canada is a major producer of peat moss and exports globally. Peatlands represent 90% of the wetlands in Canada and cover 113 million hectares. Of that, 0.02% is currently being harvested, and a total of only 0.03% is or has been harvested.
To put that into perspective, the area of Canada’s peatlands would cover the area of California three times over. The area that has been harvested fits within Fresno city limits.
The annual new growth of peat in Canada each year is 20 million tons and only 1.1 million tons is harvested each year. It is accumulating much faster than the rate of harvest.
“Canadian government regulations require that bogs be returned to functioning wetlands once extraction is complete“. It is debatable how effective these efforts are, however “The North American Wetlands Conservation Council estimates that harvested peatlands can be restored to ‘ecologically balanced systems’ – if not peat bogs – within five to twenty years after peat harvesting”. Some feel that restoration of the original peat bogs will not happen in anything less than hundreds of years but with new harvesting techniques that is no longer true.
In the UK peatlands have been overused, mostly because they have been in use for hundreds of years. Even were peatland still exists, the drainage of water has damaged many of them and this is a much bigger problem than harvesting peat for horticulture. The drainage of wetlands, and the use of peatlands for forestry and agriculture are serious problems, especially in Europe. The impact of harvesting horticultural peat is negligible.
Is peat a Renewable Resource?
Some people consider peat to be non-renewable because it accumulates very slowly – a millimeter a year. Others point to the fact that only a small fraction of the accumulated amount is harvested. For example, on an annual basis Canada only harvests 1/20 of the new peat that is formed naturally. How can something be consider non-renewable if we have more each year than the previous year?
Governments have labeled peat as a slow renewable resource, which seems to be a good description.
Environmentally Sound Harvesting Methods
You might think that harvesting peat moss is a lot like open pit mining, where big trucks come in and harvest everything, leaving a big hole. That is not even close to being true, at least not in Canada. Here are the steps in harvesting.
- The surface vegetation is cleared from a potential new harvesting field.
- Water level is lowered, but maintained at a critical level to prevent decomposition of the peat.
- The living sphagnum moss is carefully removed and used to restore older harvested fields.
- The peat is allowed to dry and then the surface is rototilled. The fine material is collected and removed. Only a thin layer is removed each year.
- The removal process continues in the same field for 10 to 50 years depending on the thickness of the peat.
- The filed is now ready for restoration and live sphagnum moss is replanted to speed up the process.
It takes only a few years for other native plants to start growing in the fields. This includes different species of moss, carnivorous plants like the Pitcher plant and the Round-leaved sundew, leather leaf, Northern bog laurel, small bog cranberry and black spruce.
It is important to understand that the bog is restored fairly quickly after harvesting stops. The regrowth of peat does take longer.
Peat and Global Warming
The loss of peatlands does impact the species living in these areas – they are sensitive ecosystems. Although this is a concern that is voiced frequently, a much more troubling concern is the impact on global warming.
Peatlands have been identified as carbon sinks, storing more carbon dioxide per unit hectare than any other ecosystem. The undecomposed plant material found in peat contains large amounts of carbon. As long as the peat is not disturbed, this carbon will not enter the atmosphere in any significant amount. As the peat is harvested and peatlands are drained for other uses, large amounts of carbon will be released into the atmosphere contributing to global warming.
Alternatives to Peat Moss
Scientists and the horticultural industry have been looking for alternatives including coir, decomposed wood, paper products and compost. The details of these are discussed in Peat and Peat Moss Alternatives. The bottom line is that nothing works as well as peat moss although some of these items can be added to peat moss to reduce the amount of peat moss that is used.
Is Coir a Better Environmental Option?
Coir is becoming more popular as a peat replacement in horticulture and many think that since it is a renewable resource, that is must be better for the environment. That is not really true. There are serious environmental impacts in the countries that make it and then it needs to be shipped long distances to customers. The appropriate choice between coir and peat moss is not obvious and may depend on where you live. It is not a good environmental option in North America and Europe that have large natural peat reserves.
Peat Moss and Peat – The Bottom Line
The following are some summary statements about the use of peat in horticulture.
- Using peatlands does have an impact on the environment, both on the local species and on global warming. The amount of peat used for horticulture is such a small component of this problem that it is a non-issue.
- The claim that harvesting peat for horticulture is reducing either the amount of peatlands or available peat reserves is not supported by the data. Peat reserves are increasing faster than they are used for horticulture.
- Canada and Russia, two of the top three producers of horticultural peat, have vast reserves and harvesting has little impact, except at the very local level.
- One can certainly make the argument that any harvesting impacts the environment and that the practice should stop. But we can make the same argument for just about any hobby, or interest that humans enjoy. If we stopped doing all of the things we like to do, including eating too much, the environment will be better off. That is not going to happen and horticulture is not going away.
After reviewing the facts about peat use in horticulture, it seems clear to me that it is not the significant environmental issue people make it out to be. However, it does make sense to look for ways to use the resource more effectively and to look for substitutes that are more environmentally friendly.
Many years ago, while in high school, i read a great book called: How to Lie with Statistics. Trivializing numbers is one technique. 113,000,000 hectares is 11 BILLION, 300 million acres. .02 percent ( gee that seems trivial )is 226 MILLION acres 226,000,000……. it that truly trivial?
Some thoughts and observations from northern Sweden.
Sphagnum moss grow more or less like weeds here clogging up ditches and such in a matter of years. Many lakes are becoming bogs and in the future peat bogs more rapidly due to a longer growth season of seaweeds and mosses.
I refuse to call it a longer summer as we here up north are acting as a can of cold beer outside of the increasingly hotter sauna closer to the equator accumulating the moisture from the air resulting in a melancholic and seamless transition from spring to autumn.
That said harvested bogs look like shit. We’re left with straight planes in the forest like abandoned agricultural land.
Some work has been done in finding high yielding cultivars of cloudberry to replant the bare bogs with as a means of income for locals.
Cloudberry blossoms are notoriously Frost tender though and when early frosts hit, which is something like three years in five, you’d have to cover them with something. Not so easy in the middle of the forest.
My conclusion on the berry issue is that it’s more of a white washing scheme of the bog miners than a universal fix.
When close to a village, probably really good and quicker turnaround than planting trees which would take 100-300 years until harvesting with mandatory thinning during their growth.
Rambling over, time for snus.
We don’t use peat directly to warm or power our homes, but we have combiplants which use peat to produce heat and electricity and heat is distributed to buildings near cities. Greetings from Finland
Most UK gardeners have given in to emotive propaganda and buy peat free composts!
They pay premium prices, often for absolute rubbish!
Come to think of it it is composted rubbish – composted green waste – with nutrients added
The same is happening on this side of the pond. People are easily convinced to do things that are good for the environment.
Maybe you’re right Robert but I’m uncomfortable with using peat. In the UK we have destroyed so much of our wild areas be they peat bogs or forests. Negative impacts include flooding, loss of biodiversity and poorer air quality. It is also harder for us to persuade other countries not to destroy their rainforests and peat bogs when we have already destroyed ours.
I am not ok with damaging ecosystems that are in decline so my plants can do a little better. Like Myrbär said, harvested bogs are scars on the landscape and take many decades to recover (centuries for the peat to reacumulate). They do not always recover. It just would not be ok for me to go into the hills here and start digging peat for my garden, leaving scars on the landscape. Maybe I see gardening from more of a permaculture standpoint.
I can understand looking at this issue differently in North America where wild areas and natural resources are still vast but here in the UK it’s a different story.
https://www.gov.uk/government/news/sale-of-horticultural-peat-to-be-banned-in-move-to-protect-englands-precious-peatlands#:~:text=The%20sale%20of%20peat%20for,peatlands%20and%20the%20natural%20environment.
The UK has lost a lot of peat lands – but not because of horticulture. Draining land for other purposes is the real problem.
Not using peat has some merit, provided the replacement is a better option.
I’ve been told the largest peat bog in North America is the Everglades. Maybe that’s true, maybe not. One thing is fairly certain, the Everglades won’t be drained and stuffed into 4.4 cubic foot bags any time soon.
Interesting article. Thanks for writing it.
Q: With regards to, “As the peat is harvested and peatlands are drained for other uses, large amounts of carbon will be released into the atmosphere contributing to global warming.”
Does this still apply even if the peat is only used for agriculture?
CO2 is released when the peat decomposes. Unharvested peat where water has drained, starts to decompose and produces a lot of CO2. The water was keeping it stable. Any peat used in agriculture or horticulture will also decompose and produce CO2.
“Peat moss is a form of peat that is created mostly from sphagnum moss.”
Not quite. Peat moss (or sphagnum moss to give it its scientific name) is something more than ‘a form of peat’. Technically, it is not peat at all since ‘peat’ is generally taken to refer to that which occurs under the blanket of vegetation that forms on top of “wet areas like bogs, mires, moors and muskeg, collectively called peatlands”. The ‘peat’ in ‘peat moss’ is used here purely in its adjectival sense. Peat moss (hereinafter referred to as ‘sphagnum moss’ in order to avoid confusion or misapprehension) is the living part of the peatland or bog. The term ‘peat’, on the other hand, refers to the partially decayed organic matter that resides under the surface or the peatland or bog. Sphagnum moss creates the conditions under which peat formation takes place. It is sometimes referred to as ‘the bog builder’ – without sphagnum, there is no peatland:
“Accumulations of Sphagnum can store water, since both living and dead plants can hold large quantities of water inside their cells; plants may hold 16–26 times as much water as their dry weight, depending on the species. The empty cells help retain water in drier conditions. Hence, as sphagnum moss grows, it can slowly spread into drier conditions, forming larger mires, both raised bogs and blanket bogs.” – Wikipedia
It will be understood from this why the extraction of sphagnum moss for horticultural purposes is a cause for concern: it involves the ripping of the living surface from the peatland or bog, leaving behind only that which lies beneath, namely, a barren brown desert that supports no significant animal or plant colonies.
Once the peatland or bog has been stripped of its living surface, the remaining peat (as distinct from sphagnum or peat moss) has no value as a horticultural product (it tends to dry out very quickly; virtually impossible to re-wet). The only remaining uses for this brown desert that was once a living peatland consist mainly in afforestation, reclamation for agricultural purposes or lifting out of the remaining peat for fuel purposes, which may be for local consumption (aka turf cutting) or for industrial scale power generation.
Another option (which is referred to in this informative article) would be that of re-flooding and seeing if peatland regeneration can take place. As the article points out however, extraction of peat for horticultural purposes only really began in earnest in the 1960s and 70s and opinions are varying as to how long restoration of the original peat bogs will happen.
It also needs to be recognised that the commercial extraction of sphagnum (or peat moss) for horticultural purposes has an impact on the future accumulation of peat reserves. So, measuring the impact may be more than a question of simply comparing the quantity of peat being accumulated annually vis-à-vis the quantity being harvested.
A final point about the extraction of Sphagnum moss for horticultural purpose is that the process is fast, complete and irrevocable (at least from the perspective of our lifetimes). It takes place within a matter of days, as distinct say, from the extraction of peat for heating purposes (or turf cutting, as it is more commonly known), where the process is slow and gradual.
I would agree with the author that this is a complex topic and look forward to future posts that deal with same.
The terms are not that clear, and the general public uses them one way, industry another. The data presented for Peat, includes fields of peat moss. Peat moss is a term gardeners in North America use for the product they buy. In Europe the product seems to be called peat more often.
Re: “It also needs to be recognised that the commercial extraction of sphagnum (or peat moss) for horticultural purposes has an impact on the future accumulation of peat reserves. So, measuring the impact may be more than a question of simply comparing the quantity of peat being accumulated annually vis-à-vis the quantity being harvested.” If the sphagnum is harvested completely and left, then it is true there is no further accumulation in that specific spot, but it still accumulates in all of the untouched areas. The comparison between amount harvested, and annual accumulation looks at the total of all areas.
Also, the industry is reseeding sphagnum in the harvested areas, so that it does accumulate in these areas as well.
As far as the International Peat Society is concerned, the terms are quite clear. In answer to the question, ‘What is Peat?’, the society suggests the following:
“Peat is a heterogeneous mixture of more or less decomposed plant (humus) material that has accumulated in a water-saturated environment and in the absence of oxygen.”
Such a definition would have to exclude Sphagnum Moss (aka peat moss or moss peat) since it in by no means decomposed. It is, in fact, living flora. This is what gardeners and horticulturalists are buying when they buy peat moss or moss peat. They are buying the living part of the bog which, once stripped from the surface, effectively results in the wholesale destruction of a habitat that has been around for thousands of years. Even if the industry is re-seeding sphagnum in harvested areas, your article points out that opinions vary as to how long it will be before restoration of the original peatland takes place. If I have understood it correctly, you are suggesting that this will take at least 100 years but we cannot even be certain on this point, since your article also points out that we have only been harvesting peat for horticultural purposes on an industrial scale for c. 50 years.
Re: “The comparison between amount harvested, and annual accumulation looks at the total of all areas.”
Before we can draw anything like a definitive conclusion, we need to look at the amount of Sphagnum moss (i.e. peat moss as distinct from peat itself) being harvested vis-à-vis the quantity Sphagnum moss (i.e. peat moss as distinct from peat itself) accumulating. Otherwise your assertion that the extraction of peat (Sphagnum moss) for horticultural purposes is renewable, comes across as tenuous and glib.
Great research as always. Question if I may, is there an update in using common comfrey in a vegetable garden as a side feeding to tomatoes and other veggies or adding comfrey to a compost pile ? We tried to research the practice but get conflicting answers. Some say safe others say liver damaging to humans.
Thank you
Joe
I doubt it is damaging to humans. Almost all organic molecules in comfrey will be broken down before being absorbed by the tomato.
What specific chemical is damaging for humans?
I just returned from Ireland and was surprised to see that every place I stayed had Peat bricks around for use in their wood stoves. Traffic was often delayed by wagon loads of Peat pulled by the local farmers. I would never have guessed it was still in such widespread use in a developed EU nation.
It is local and cheap. Imported oil is not. I was surprised too.