ISCF WAVE 1 AGRI TECH: Sphagnum Farming UK - A Sustainable Alternative to Peat in Growing Media

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The current commercial extraction of peat for use as a growing media in horticulture is widely acknowledged as unsustainable, is destroying increasingly rare and highly-valued ecosystems, is having an adverse effect on carbon emissions, and is becoming increasingly difficult to sustain within the constraints of the planning process. A high-quality alternative to peat as a growing medium is urgently needed if the growing media industry is to have a long-term future. Commercially farmed Sphagnum moss could provide this because the highest-quality horticultural peat consists largely of semi-decomposed Sphagnum leaf and stem fragments. Fresh Sphagnum provides the same characteristics and properties as high-quality peat but cannot currently be readily obtained from the wild because Sphagnum-rich areas have become increasingly rare and those which do remain are largely now protected under environmental legislation. Sphagnum farming, on the other hand, offers the potential to provide a sustainable supply of high-quality growing medium into the foreseeable future. Such farming requires a source of starting propagules at the outset, however, to generate the initial crop. This is currently a significant obstacle for the same reasons that make wild harvesting of fresh Sphagnum undesirable and difficult. Until now it has not been possible to propagate and grow Sphagnum in large quantities, a limitation which has prevented active consideration of the possibilities offered by fresh Sphagnum. Micropropagation Services Ltd (MPS), however, have researched a unique laboratory technique for the micropropagation of Sphagnum which now offers the potential to grow this moss on a commercial scale. This novel solution involves the mass production of Sphagnum from leaf fragments using sterile tissue culture - micropropagation. Since 2008 MMU has supplied research support to MPS to develop methods of planting propagated Sphagnum in the field for habitat restoration. The scale of restoration using these methods in northern England is significant, having increased to 1,000 ha of upland peatland in 2013-2015.The current project proposal aims to establish the underpinning processes, the cultivation requirements and the production potential involved in growing Sphagnum on a scale sufficient to form source material in quantities which would make Sphagnum farming a viable proposition using cultivation techniques which are applicable at the farm-field scale. Our project will focus on an area of peatland which has previously been used for commercial peat extraction but which has now reached the end of its commercial life because there is little peat left to extract. MMU research within the consortium project will be strongly integrated with approaches at smaller and larger scales led by the other partners. MMU will field test the growth of selected Sphagnum genotypes in experimental small field plots; we will investigate the possibility of increasing production through nutrient addition. Drained peatlands are a source of respiratory CO2. Re-wetting and cultivation of Sphagnum has the potential to sequester carbon through raising CO2 assimilation in photosynthesis and cutting CO2 losses in respiration. However, the switch from a dry to a wet peatland may stimulate methane (CH4) emissions from the bog surface and surrounding irrigation ditches. The time-course and net benefits of wetting and Sphagnum cultivation on carbon exchange require evaluation. Nutrient demand and cycling by Sphagnum farming has not been assessed but requires investigation in order to provide optimal supply for production while minimizing losses such as emissions of the greenhouse gas nitrous oxide or release to water courses of dissolved inorganic nitrogen. Increased knowledge learned from MMU research will guide product development through improvement of Sphagnum production within an environmentally sustainable farming system.