The Peat Report: How Producers Harvest

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The Peat Report: How Producers Harvest

A harrow prepares the bog for harvesting, loosening the
surface before vacuum harvesters collect the peat.
The process is commonly called “milling” the peat.

The picture a few people have painted of the peat industry is one that depicts producers as raiders who rapidly strip the earth and abandon peatlands without concern for the ecosystem.

Fortunately, that picture isn’t the accurate one here in North America. Peat producers don’t function as miners, and they aren’t exactly farmers either. But, as Sun Gro Horticulture’s Robert Lapointe says, the peat industry functions somewhere in between the two.

According to the Canadian Sphagnum Peat Moss Association (CSPMA), at least 70 million metric tons of peat accumulate each year in Canada. Over that same year-long span, 1.3 million metric tons are harvested across the country.

That means Canadian peat is accumulating at a rate that’s more than 50 times faster than the rate at which it’s being harvested. Considering the percentage (0.02 percent) of Canadian peatlands that are being harvested for horticultural use, plus the rate at which peat is currently being managed by horticultural peat producers, Canadian peat will theoretically be available for years to come.

Vacuum harvester operators often work in teams
collecting peat because drain ditches on the
sides of peatlands are typically 80 to 100 feet apart.

“Peat is a sustainable resource, just not in the same way as, say, forestry is sustainable,” says Roelof Drost, Jiffy International’s director of marketing. “Peat grows slowly and it will take a long time to grow a layer of peat matching the harvested quantity. However, the total area of bogs in relation to total area harvested in Canada is currently about 1 acre for every 6,000.”

So what exactly does peat harvesting entail? And how else is peat used in North America? Let’s explore.

Site Selection & Preparation

Of course, before peat is harvested, producers need peatlands on which they can harvest. As Premier Tech Horticulture’s Jacques Gagnon describes, peatlands are generally controlled by each of Canada’s provincial governments. A public allocation system is used to open new peatlands in every Canadian province except New Brunswick.

In New Brunswick, the Department of Natural Resources occasionally make peatland sites available to producers. Producers will then bid on the available peatlands, but the eventual buyers must first complete an environmental impact assessment and have the government approve their assessment before any peat harvesting takes place.

“Before you get authorization to harvest a bog the government leases you, you have to propose a way to restore it,” says Gagnon, Premier’s peatland restoration director.

It is also now required, Gagnon says, to keep a portion of the peatlands producers have as reserves. He refers to those reserve peatlands as “donor sites” and says the goal of the requirement is to leave 10 percent of the surface untouched so fresh sphagnum is available for restoration.

Did You Know?

–Peatlands cover 988 million acres on the planet, or 3 percent of its surface. Nearly 90 percent of peatlands, or 865 million acres, are located in the Northern hemisphere.

–Sphagnum grows 2 to 12 centimeters per year, depending on the type of peatland. With the decomposition and the compaction of plant residues under the sphagnum on site, the peat accumulating rate is evaluated at 0.5 to 1 millimeter per year in a pristine bog.

Source: APTHQ (Quebec Peat Moss Producers Association)

Still, producers won’t bid on just any peatland. Producers take multiple factors into account when selecting sites for harvest, including whether or not the peat on site meets market requirements, the thickness of the peat layer available and the total area of the site. Most occupied peatlands are at least 200 acres, although smaller sites are sometimes developed for production.

“Responsible peat harvesting means having the conscience that we are using the bog temporarily, being respectful to the bog and eventually bringing the bog back as close to its original state as possible when finished harvesting,” Drost says.

CSPMA indicates that once a peatland has been selected for development, the land is surveyed and a drainage plan is prepared. A drainage ditch is always dug around a perimeter, and it is drained to the lowest side of the peatland. Vegetation on the surface is removed once the perimeter ditch is dug.

Reducing moisture on the top layer of the bog is a key, as well, so shallow parallel ditches are dug and spaced 80 to 100 feet apart. Those parallel ditches are important because a drier surface allows harvesting equipment to operate on peatlands without sinking.

The Harvest

The sun and wind are a harvest’s key elements because dry surfaces are a must. Producers usually harrow the peatland’s uppermost layer to loosen the peat a few days before vacuum harvesters make their rounds collecting it. Gagnon says producers generally harvest fractions of a millimeter each time. The harvesting season traditionally runs April through October, and within each season there are usually 40 or 50 days that are suitable for harvest.

Because such small amounts are harvested in each pass, producers are capable of operating on the same sites for years–even decades. St. Modeste, a Berger Peat Moss peatland site Greenhouse Grower visited in September, for example, is still in operation today after breaking ground in 1963.

“If you have a peat bog that’s 10 to 15 meters deep, you can use it for 30 to 40 years,” says Martin Emond, Berger’s communications and marketing manager.

Other Functions

Greenhouse floriculture, to the surprise of some, isn’t the only industry that uses peat. Although its use as a growing medium is Canadian peat’s most common use, it is also used as an absorbent, a biofilter and for body care.

As an absorbent, peat can be used to clean up hydrocarbon spills on land and at sea. According to the Quebec Peat Moss Producers Association, peat can be made water repellent by undergoing a thermal shock. Peat has a water-repellent property, in fact, that allows it to hold off water for 48 hours.

Biofiltration, a pollution control strategy that uses living material to capture and degrade process pollutants, is yet another use of peat. It isn’t a common use in North America, but peat is used as a biofilter on some composting sites and agricultural processing plants.

Peat can also be used for body care. Because peat mud has a high thermal capacity, it is an ideal material for massage therapy. Peat promotes relaxation, and it stimulates the bloodstream.

Kevin Yanik is the former managing editor of Greenhouse Grower.

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