Environmental impact of peat alternatives in growing media for European mushroom production

Button mushrooms are an important protein source with a production of >48 million metric tonnes in 2021. Several life cycle assessments (LCAs) have been employed in assessing mushroom cultivation. This paper assessed potential impacts of relevant alternatives (sphagnum moss, grass fibres, spent casing and bark) to peat as casing materials for mushroom production across Europe by using LCA using a cradle to farm gate approach. Here, we: i) compared the environmental impacts of mushroom produced with different growing media across Europe ii) identified environmental hotspots across the value chains of mushroom growing media and iii) provide insights on the sustainability of mushroom growing media production. Two functional units have been used the kg and € of harvested mushrooms. Data were gathered from mushroom producers and casing processors across Europe. Changes in casing material for mushroom production caused environmental trade-offs, by reducing the resource use for fossil and by moderately changing (<7.7 %) all other impacts assessed here except the bark used as casing material which caused a reduction for all impact categories. Thus, each of the casing alternative material could substitute peat in mushroom production with limited environmental impacts if productivity does not decrease. LCA demonstrated advantages or disadvantages of replacing part of the peat casings by other alternatives (e.g., sphagnum moss, spent casing, grass fibre, bark). As switching to alternatives becomes more urgent in the near future, potential trade-offs, advantages and disadvantages of using less peat need to be identified using a broader range of alternatives.