Inagro tests reduced peat and peat free substrates in PEATLESS
The PEATLESS project is moving from experimental screening towards validation in research facilities. Inagro is testing reduced-peat and peat-free mixtures under controlled conditions designed to reflect commercial production systems. The work covers two applications: casing soils for mushroom cultivation and substrates for seedling propagation.
More than 25 mushroom casing soil formulations under assessment
At Inagro’s mushroom facilities, more than 25 alternative substrate compositions are being assessed as casing soils alongside a traditional casing soil reference. Several of the formulations are peat-free.
The trials follow each formulation through the cultivation cycle. The evaluation covers mycelial growth in the casing soil, pinning conditions, irrigation strategy and yield across different flushes. Several formulations from the initial trials are already showing encouraging results compared with the traditional casing soil, although the assessment is still in progress.
The trials are producing two kinds of evidence: encouraging early results for some mushroom formulations and a clear need to reformulate the substrates tested for seedlings.
Seedling trials identify a growth delay that needs further investigation
In parallel, several substrate mixtures were prepared, analysed and tested for their suitability for pressed soil blocks. Five blends were selected for further evaluation with lettuce, cauliflower and organic celeriac. Pressed blocks were used for lettuce and celeriac, while trays filled with the selected substrates were used for cauliflower. Each crop trial included a standard substrate as a control.
During propagation, the team observed uneven emergence and a pronounced growth delay across the treatments. The trials were therefore stopped early so that the substrate compositions could be reassessed. The cause of the growth delay is not yet known.
Left: cauliflower seedlings showed marked variation in plant growth. Right: celeriac growth was delayed in all tested substrates compared with the standard mixture.
Preparing the next phase of semi commercial trials
The next step is to select the best-performing alternative formulations for mushrooms and seedlings and validate them in semi-commercial trials at Inagro. Testing under conditions closer to commercial production will show how the selected blends perform beyond the initial experimental setting.
Throughout this phase, the sensor system developed by PEATLESS partner CESENS will monitor key parameters. This monitoring will help the project understand how the formulations behave during cultivation and support the selection of blends for the following stage.
From validation to demonstration with growers
At a later stage, the most promising substrate blends will be introduced at commercial seedling and mushroom production sites. Growers will use the formulations in their daily operations, while the sensor system continues to capture how each blend performs under real cultivation conditions.
This sequence, from controlled trials to semi-commercial validation and then commercial demonstration, is intended to connect experimental formulations with the practical requirements of the seedling and mushroom sectors.
About Inagro
Inagro, based in Belgium, is a multidisciplinary centre of expertise for agriculture and horticulture. Its facilities support practice-oriented research, validation and demonstration in real-life environments across a wide range of crops in conventional and organic farming systems.
Within PEATLESS, Inagro is a research partner and leads Work Package 3, which addresses socio-cultural barriers. The organisation is also closely involved in Work Packages 1, 2 and 5.
