Peat is a dark, fibrous material formed in waterlogged landscapes across the globe. This natural resource consists of partially decomposed organic matter, primarily derived from ancient mosses and plants, which accumulates in wetland environments. Historically, peat provided a localized source of energy, but its dominant modern application is in the horticulture industry. The use of this resource involves a trade-off between its beneficial properties and the significant environmental consequences of its extraction.
The Formation and Nature of Peat
Peat forms over millennia in wetland ecosystems, such as bogs and fens, collectively known as peatlands. The process requires waterlogged, oxygen-poor (anaerobic) conditions, which severely restrict the activity of microbes responsible for decay. This allows dead organic material to accumulate, as the rate of plant growth far exceeds the rate of decomposition.
The primary component is often Sphagnum moss, which creates the acidic environment that further slows decomposition. This slow accumulation means peatlands grow at a slow rate, sometimes as little as one millimeter per year. For a meter of peat to form, it can take anywhere from 600 to 2,400 years, making it a non-renewable resource on a human timescale. Peat is considered an earlier stage in the formation of fossil fuels like coal.
Peat’s Primary Role in Horticulture
Today, peat’s main commercial use is as a component in potting soils and growing media for commercial and domestic horticulture. The material is valued for its physical properties that create an ideal environment for plant roots. Peat moss can retain a large volume of water, sometimes up to 20 times its own dry weight, which helps reduce nutrient leaching and provides a steady moisture supply.
Its fibrous structure prevents soil compaction, promoting excellent aeration and allowing roots to absorb nutrients efficiently. Peat naturally has a low pH, typically ranging from 3.5 to 4.5, which benefits acid-loving plants and allows manufacturers to adjust the acidity level precisely for different crops. Harvested peat is sterile, being free of weed seeds, pathogens, and harmful microorganisms, making it a reliable medium for starting seeds and growing sensitive plants.
Peat’s Use as a Traditional Fuel Source
Before its widespread use in gardening, peat was a traditional fuel source. For centuries, communities in countries like Ireland, Scotland, Finland, and Scandinavia harvested peat to heat homes. Traditionally, the peat was cut by hand into sods, or “turf,” and laid out to dry before being burned.
In the 20th century, industrial-scale extraction emerged, and peat was used to generate electricity in power stations, particularly in Ireland. Dried peat burns consistently, and although it provides less energy than coal, its local availability made it a strategic fuel source. Even today, peat is still used in some regions for domestic heating and contributes a distinctive smoky flavor to certain Scotch whiskies.
Environmental Impact of Peat Extraction
The extraction of peat has significant environmental consequences, primarily due to the destruction of the peatlands themselves. Peatlands are the largest natural terrestrial carbon store on the planet, holding approximately 550 gigatons of carbon globally—nearly twice the amount stored in all the world’s forests combined. When these wetlands are drained for extraction, the stored organic matter is exposed to oxygen, which accelerates decomposition.
This exposure causes the release of carbon dioxide and other greenhouse gases like nitrous oxide into the atmosphere, transforming the carbon sink into a carbon source. The degradation of peatlands, which cover only about 3% of the world’s land surface, is responsible for a disproportionate amount of global carbon dioxide emissions. Beyond climate change, the ecosystem is destroyed, leading to the loss of unique habitats for specialized bog flora and fauna.