Peat and Peat Moss – The True Environmental 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 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.