Reducing Peat Use in Mushroom Cultivation: Exploring Sustainable Casing Alternatives
The cultivation of button mushrooms is a key sector within European horticulture. With an annual production of around 160,000 tonnes, Spain ranks as the third-largest producer in Europe, after Poland and the Netherlands. Beyond its economic importance, this crop also plays a significant nutritional role, responding to growing consumer demand thanks to its versatility and health benefits.
However, this production model relies heavily on peat, which is widely used as a casing material to induce fructification. On average, around 1.5 m³ of peat is required to produce one tonne of mushrooms, resulting in an annual consumption of approximately 240,000 m³ in Spain alone.
The challenge of peat dependence
Peat plays a critical role in mushroom cultivation, particularly during the fructification phase. Its physical and chemical properties make it suitable for casing layers, helping regulate moisture and supporting mycelium development.
At the same time, this dependence raises important sustainability concerns. Peat is a non-renewable resource, and its extraction can have a significant environmental impact by affecting sensitive ecosystems and contributing to the release of stored carbon.
For the mushroom sector, this creates a pressing need to identify more sustainable production models that do not compromise yield or product quality. In this context, the PEATLESS project can be linked here, as well as Horizon Europe, since both references help frame the wider purpose of the work.
Understanding casing materials
To help explain this process, CTICH created a video that shows how casing materials work in mushroom cultivation and why peat has traditionally played such a central role.
This kind of materials are especially useful for illustrating the functions that casing materials need to fulfil, such as:
- Retaining water
- Supporting irrigation management
- Enabling mycelium development
- Favouring the progression of fructification
The role of CTICH in the PEATLESS project
Within the project, CTICH (La Rioja Mushroom Research and Technology Centre) is working to identify and develop alternative raw materials that could replace peat in mushroom cultivation. The objective is to find solutions that are sustainable, renewable and technically suitable for use as casing materials.
To support this work, CTICH has collaborated closely with mushroom growers and other stakeholders involved in the production and distribution of growing media. Through a series of collaborative sessions, the project gathered valuable insights into the sector’s concerns, practical needs and expectations regarding alternative materials.
These discussions also helped define the key properties that potential casing materials must meet, including:
- Water retention capacity
- PH
- Irrigation requirements
From stakeholder input to material screening
Building on this exchange with stakeholders, the CTICH team contacted substrate producers and distributors to obtain a broad range of candidate materials and formulations. More than 45 materials have already been analysed at the centre’s facilities, where their physical and chemical properties were evaluated.
Following this screening process, the materials that met the essential requirements for mushroom cultivation were selected for further work. This step enabled the theoretical design of several alternative casing mixtures.
Some of these formulations are completely peat-free, while others include a reduced amount of peat, never exceeding 30%, which already represents a significant reduction compared to conventional practice.
Testing alternative mixtures
These mixtures are now being tested at laboratory scale at CTICH. In total, 12 alternative mixtures are being evaluated against a control made entirely of peat.
The aim is to assess their behaviour under real cultivation conditions, with particular attention to:
- Moisture retention
- Irrigation management
- Mycelium development
- The progression of fructification
This phase is essential to determine the viability of the proposed alternatives before moving to larger-scale trials.
Toward semi-commercial validation
Based on the results obtained, at least five mixtures will be selected for a semi-commercial phase in CTICH’s cultivation rooms.
This next step is particularly important, as it will make it possible to validate the most promising alternatives in a more realistic production environment and bring the sector closer to scalable solutions.
Supporting a more sustainable production model
Through this work, the PEATLESS project is helping to advance the validation of sustainable solutions that can reduce dependence on peat in mushroom cultivation and support a more environmentally responsible production model.
