Industrial peat-harvesting in the Bog of Allen, County Offaly, Ireland
Use of peat in horticulture
Traditionally gardeners and growers made their own potting compost using locally available materials such as leaf mould, animal manure and grit. As the horticultural industry developed, the need for standardised composts grew and in the 1930’s the “John Innes” range of mixes were developed, made from blends of ‘loam’ (composted grass turves), peat and sand. However, quality loam was both difficult to source and heavy making transport and handling expensive. In the 1970’s, peat replaced loam as it was light, cheap and easily available in Western Europe. It probably took 10-15 years for people to be confident in using the peat dominated mixes.
In 2012 total potting compost used in horticulture in the UK was ~ 3.9 million cubic metres (m m3) with peat use being ~ 2.2 m m3. In terms of peat, the amateur market used 1.4 m m3 while the professional market (commercial growers) used 0.8 m m3. In the same year the amateur market used 1.3 m m3 of peat-free compost while the commercial growers used 0.4 m m3. In 2011, the UK Government’s White Paper on the Environment contained voluntary targets for ending peat use in horticulture. The aim was for all public-body compost use to be peat-free by 2015, all amateur retail potting compost to be peat-free by 2020 and all commercial use to be peat-free by 2030. In response to this, the industry and Defra came together with all stakeholders involved (potting compost manufacturers, retailers, growers, NGO’s etc) and proposed a “road map” for how they would take the issue forward.
By 2018 the process will have developed quality, sourcing and labelling standards so that consumers should be able to buy potting media with confidence that is responsibly sourced and will be fit for use.
Substitutes for peat
The goal is to replace peat with sustainable components, preferably sourced close to market. This will need a variety of raw materials rather than just one source, and they will need to be blended to balance their physical and chemical properties as well as interacting with any added nutrition and managing the provision of water for the plant in a predictable fashion. Read more about these potential substitutes in our leaflet here.
Coir compost originates from waste fibres from the outer shell of coconuts, and the main sources are India and Sri Lanka. Coir has a number of useful properties, including its low nutrient status, high porosity and low bulk density. On the other hand, it does not readily retain nutrients and is easily leached, and there are environmental sustainability issues about its production and transport.
Composted green waste
This “green compost” is made by bulk-composting material from the waste stream that would otherwise go into landfill. It has high nutrient concentrations and good water holding capacity, but isn’t reliable for growing mixtures, because of inconsistency, high pH and tendency for contamination. It is probably best use as a nutrient rich additive, at up to 25% in other mixes.