By Liz Sellors, Master Gardener
It’s spring! Gardening advertisements are bombarding us! Like this one :
“Peat is a natural product, sustainably harvested. Environmentally friendly. Our products are primarily based on the renewable resource of Sphagnum peat, THE recognized medium for reliable, efficient and high-yield plant breeding worldwide. The world grows more than 10 million plants in our peat pots.”
The first documentation of peat having been used horticulturally was in the 1940’s through experiments that created standardized horticultural growing media that consisted of loam, sand and peat. By the 1950’s, soilless culture became the plant substrate of choice in greenhouses and containerized nurseries. Canadian sphagnum peat mixed with loam was the culture of choice.
Peat has the advantages of being light weight, cheap and readily available. It improves soil structure, reduces nutrient leaching by improving the cation exchange capacity, aerates soils, improves drainage in heavy clay soils, assists roots to grow, absorbs nutrients and retains water up to twenty times its weight. It is free of weeds and supports no insect pests.
Its attributes have been deemed so essential, that today, peat is considered an irreplaceable part of a vast horticultural industry. Mixed with other ingredients, peat often makes up between one-third and two thirds of the total volume of most horticultural substrates. It is the most-used organic horticultural material in the world. It is so ubiquitous, that the average gardener accepts its presence in their potting mixes and peat pots, without question, although most have no idea what peat is, or where it comes from.
Peat is mined from very fragile ecosystems. Peatlands are wetlands where soils consist almost exclusively of organic matter derived from the accumulation of buried plant material waste that has been submerged in water for thousands of years. Peatlands are typically several meters thick, having taken more than 10,000 years to develop. The oldest peatlands are estimated to be approximately 360 million years old.
Over the years, the organic matter of the peatlands breaks down into what is referred to as peat. According to the International Peatland Society, peat is defined as “sedentarily accumulated material consisting of at least 30% dry mass of dead organic material.” Peatlands decompose slowly through anaerobic conditions. In boreal and temperate regions of the world, sphagnum mosses dominate large areas of peatlands. Sphagnum and peat are two different forms of the same plant. Sphagnum grows on the top of peatlands, while peat is the layer of decaying, water-logged sphagnum that has sunk below the surface. Together, they form an unbroken covering of peatland on which rare and unique plants establish and grow.
Under normal circumstances, the peatlands absorb carbon dioxide and lock carbon into the plant structures as peat decays. Scientists believe that peatlands contain more carbon than what has been estimated to exist in all the world’s rainforests. Estimates calculate that peatlands store upwards of 550 billion tonnes of soil organic carbon, twice that stored in forests, and approximately 30 percent of the world’s carbon stores. When peatlands are mined, the organic matter is removed through vacuum extraction and the water is drained from the wetland. The drying peat decomposes releasing carbon dioxide, a potent greenhouse gas, into the atmosphere.
The horticultural industry argues that once the mining process is complete, peatlands can be restored. But, many peatlands are simply abandoned and left in a degraded state once the mining process is completed. With the current understanding of the connection between peatlands and climate change, attempts at restoration are seen as critical. Restoration of peatlands is complex, difficult to accomplish and very expensive, requiring considerable human intervention. Some successes in restoration have been reported, the work can take decades and attempts are often abandoned. One downside of the reclamation process is the negative effect it can have on the ecology of the immediate and surrounding area, putting plant and animal species at risk. Restored peatlands often bear little resemblance to natural ones, lacking the original biodiversity, tending toward monocultures and altering adjacent waterways. Most importantly, no amount of mitigation can address the release of carbon dioxide that has taken place during mining. The general consensus is that having taken thousands of years to evolve, once mined, degraded peatlands cannot be restored fully. Currently, worldwide, approximately 46 million hectares of peatlands are in a degraded state, emitting greenhouse gases. Because mining peat continues, attempts at restoration must be carried out to address the release of some 394 million tonnes of carbon dioxide released per year, a figure equivalent to the annual emission from 84 million operating passenger vehicles.
Peatlands exist in 180 countries around the world and make up approximately 3% of the world’s surface area. Canada and Russia have the most extensive peatlands. In Canada, peatlands exist in all ten provinces covering a total land area of approximate 113.6 million hectares, the equivalent of 13% of Canada’s surface area. One third of Manitoba is peatlands, currently unprotected from peat mining. In 2016, the present Manitoba government reversed a 2014 commitment to protect wetlands and peatlands in the province. The Manitoba Government is currently in negotiations with the peat mining company, Sun Gro Evergreen Mine to mine peat in the Interlake. While there is no contract in place, it would appear the Manitoba Government intends to proceed. As shown in photographs taken by The Wilderness Committee, Sun Gro has started “work before licensing” by clearing the land in preparation for mining peat. Manitoba has no target timeline for the environmental protection of peatlands.
Despite scientific warnings that peat mining must be stopped and peatlands preserved to mitigate climate change, extraction and infrastructure development continues and at present accounts for 10% of greenhouse gas emissions globally. In 2016, the United Nations formed The Global Peatlands Initiative in an effort to preserve peatlands as the world’s largest terrestrial organic carbon stock. Countries were encouraged to keep carbon locked in peatlands and, at the same time, attempt to conserve, restore and sustainably manage damaged peatlands. But, is this possible? The horticultural industry views peat as indispensible, the gold standard of the horticultural industry, the unabandonable substrate, and places its commercial value far above its environmental contribution. Commercial horticulture is a high-tech industry arguing that peat’s properties are unmatched by any other raw material, and that alternative substrates are unavailable in sufficient quantities for the demand. Some attempts have been made to increase the proportion of alternative substrate constituents to reduce dependency on peat, but so far 85% of all horticultural substrate remains peat. This year the horticultural industry will continue to use millions of cubic meters of peat.
To keep customers reliant on peat, marketing strategies use words such as renewable, organic, sustainable, free of pathogens, bacteria, bugs and weed seeds. There is no shortage of peat available in horticultural products in Manitoba. Manitoba soils sold in bulk are readily available in various mixes such as 2-way, 3-Way, 4-way and 5-way, all of which contain varying degrees of peat, some as much as 70%. And, most bagged potting mixes are peat-based.
In the search for suitable alternatives to using peat, products such as “cow pots” made from cow manure, Organix Re-peet (digester processed dairy manure), pulp containers made from recycled paper, chipped bark, wood waste, composted vegetable waste, shredded tree prunings, leaf mold, straw, spent mushroom compost, pine needles, composted garden scraps, green kitchen waste, leaf mold and well-rotted farm manure have all been proposed as peat alternatives. While they cost less, the greatest downside is their unavailability in quantities that can compete with peat. Coir, made from retted coconut husks, is often suggested as a peat substitute and can be available in large quantities, but because 90% of the total output is processed in Sri Lanka, India and the Philippines, shipping gives it a hefty carbon footprint.
By far, the environmental factor is the greatest concern related to peat mining, but it is not the only one. Peatlands have historical value. The acidic conditions that cause slow decay within peatlands provide an historic record of climate, vegetation types and human activity over the millennia. This history is destroyed along with the ecosystems when peatlands are mined. Peatlands have unique flora and fauna found nowhere else. These too are destroyed. Through their ability to filter and purify water, intact peatlands are referred to as “global cleaners”, contributing to healthy watersheds and preventing floods. When ditches are dug to extract peat, the water table is lowered, destroying or degrading local waterways, lakes and wildlife habitats.
Additional aspects of peat mining that are less obvious, but of serious concern:
• In addition to carbon dioxide, peat mining releases sulfur dioxide, nitrous oxide and methane. Nitrous oxide emitted from peatlands is approximately 265 times more potent than carbon dioxide at effecting atmospheric warming.
• Degrading peatlands release heavy metals, including mercury, all of which find their way into local waterways and lakes.
• Peat mining alters water tables, killing local trees and plants.
• For First Nations people, destruction of plants in peat mining sites means loss of traditional medicine practices.
• Significant road infrastructure damage is incurred from heavy trucking traffic. Heavy equipment degrades roads, impacts safety, increases dust, noise and vibrations. Revenues from leases and royalties to peat mining companies do not cover the road degradation costs. Repairs and replacements are the responsibility of local jurisdictions and municipalities.
• As mined peat dries, fires can occur along with igniting forest fires and creating explosions. Peat fires are difficult to extinguish and can last for months, emitting CO2 and mercury at a rate 15 times higher than a forest fire.
• There is the potential health risks to humans and fish habitats from the dust produced through the mining process.
Reversing climate change requires long-term planning, sacrificing and determination to reach goals. Political cycles are relatively short, and the interests of economically vested groups are even shorter. This is particularly true with respect to peat mining. But, there are ways in which individuals can take a stand against climate change being caused by peat mining. There are a number of organizations dedicated to the responsible management and wise treatment of peatlands. Becoming a member of an international organization such as the International Peatland Society (IPS) provides awareness of the global peatlands situation. The IPS was constituted in Quebec in 1968. It is an organization of individuals, corporations and institutions that currently has members in 33 countries. It keeps members, businesses representatives, scientific groups, cultural organizations and regulatory bodies informed and up-to-date through scientific papers, conferences, symposia and workshops. It publishes and distributes research from scientists and industry leaders. This year the IPS is holding a number of virtual events, including the Second Annual World Peatlands Day on June 2nd. Gardeners can celebrate the day by making others aware of the dangers peat presents to the world through our gardens.
Published: May 2021