Garden Myths - Learn the truth about gardening

Peat and Peat Moss – The True Story

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 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?

I have been following this story for some time, and I believe that much of the information is misunderstood. There are too many myths and it is time to try and sort things out. It’s a complex topic that will require several posts to tell The True Story About Peat.

86% of global peatlands remain undisturbed. This chart shows how the remaining 14% has been used.

86% of global peatlands remain undisturbed. This chart shows how the remaining 14% has been used.

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 is dark and shows few signs of the plant material that went into made 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 (ref 1) provides a detailed spreadsheet of peat reserves on a global basis for 1999.

Peatland distribution globally

Peatland distribution globally

Here is some data for specific countries (ref 1 and 2):

Amounts of peat by country, peat moss, peatlands

Amount of peat in some countries

It is important to understand the units being discussed; is it area or volume? The apparent inconsistency in the above table can be explained by the fact that peat exists in different thicknesses. Although Canada has the largest area, it does not have the largest amount 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 come away thinking that this is a modern day problem, but it’s not. It 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 (ref 3). 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 1070s.

Of the peat that is currently harvested globally for heating and horticulture, 60% is used for heating, and 40% for horticulture (ref 3).

These numbers clearly show, that horticulture has not been a significant factor in the loss of peatlands.

Peat as a Heating Source

peat harvesting for heating

Peat mining in Ireland.

As you drive through the countryside in Ireland, 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.

 

 

 

peat harvesting for heating

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 peat extraction (ref 4). 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 (ref 3). 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 0.03% is or has been harvested (ref 5).

The annual accumulation of new peat in Canada is 20 million tons with only 1.1 million tons being 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”, (ref 6). 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”, (ref 6). Some feel that restoration of the original peat bogs will not happen in anything less than hundreds of years.

 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 effect of harvesting horticultural peat on this problem 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 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.

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.” (ref 3). 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.

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 a very small part of this 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 produces 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. I’ll look at some options in my next post.

References:

  1. Peat as an Energy Source; http://www.peatsociety.org/peatlands-and-peat/peat-energy-resource
  2. Peat Usage Data; https://minerals.usgs.gov/minerals/pubs/commodity/peat/mcs-2016-peat.pdf
  3. USGS 2013 Minerals Yearbook for Peat; https://minerals.usgs.gov/minerals/pubs/commodity/peat/myb1-2013-peat.pdf
  4. The Use of Energy Peat in Finland; http://www.asocdurpes.lt/forum2013/downloads/J.%20RAMO_The%20use%20of%20Energy%20Peat%20in%20Finland_05%2009%202013_EN.pdf
  5. Peat and Peatland Statistics; http://peatmoss.com/peat-moss-industry-figures/
  6. Does Peat Moss Have a Place in the Ecological Garden?; http://www.life.ca/naturallife/0712/asknlpeat.html

 

If you like this post, please share .......
Robert Pavlis
Editor of GardenMyths.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Myths an educational site that helps you understand your garden better.

15 Responses to 'Peat and Peat Moss – The True Story'

  1. Myrbär says:

    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.

  2. Eepi says:

    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

  3. Roger Brook says:

    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

  4. daryleone says:

    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.

  5. Phillip Soltan says:

    Interesting article. Thanks for writing it.

  6. jdmumma says:

    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.

  7. Editor says:

    “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.

      • Editor says:

        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.

  8. Joe says:

    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?

  9. Art Thompson says:

    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.

Please let me know what you think - Leave a Reply