The molasse is formed by a series of horizontal layers of cemented and silty sandstone interspersed with layers of marl and argillaceous rocks.  The molasse in the region is generally made up as follows:

• 30 to 50% clay,
• 10 to 15% silt,
• 10 to 15% sand, with a grain size of between 63 μm and 4 mm,
• 15 to 20% sandstone particles larger than 4 mm.

The molasse material was processed through screening, crushing, and sieving to achieve a final particle size below 20 mm. The mixture consisted of two-thirds of a molasse containing a higher content of marls and one-third of molasse with a higher content in sandstone, to optimize substrate texture and account for the natural variability in the chemical and geo-mechanical composition of the molasse. The molasse was then mixed with a low compost quantity, before being installed in the experimental plots. The minimization of the quantity of compost, a precious resource for the agricultural activities in the region, is in line with the requirement of integration of the project into the regional socio-economical activities.

In addition, a novel mixing method is being tested to enhance soil porosity by forming substrate pellets, which could improve root penetration and plant growth. The process aims to create a durable and fertile substrate while optimizing its physical properties.

In the OpenSkyLab tests, the soil construction is initiated in a two-step process: creation of a primary and soil structure management. The first step involves characterizing raw materials to create an environment suitable for microbes, plant roots, and soil fauna. The second phase focuses on optimizing organic matter stabilization and pore creation, which are essential for long-term soil productivity. Strategies include using diverse plant species, plants with extensive root systems, perennial plant species and microbial inoculants, while limiting resource input to ensure scalability for larger applications.  

A field monitoring system “OpenSkyView” was developed to provide a comprehensive overview of the experimental plots, gathering data from various sensors, drone imaging as well as more traditional sampling events. It allows to track soil properties and meteorological data in real-time, and to monitor parameters such as biomass growth, soil moisture, matrix potential, temperature, and evapotranspiration.

The substrate mixtures tested in the OpenSkyLab project are designed for large scale applications, suitable for suitable for major construction projects, research infrastructure, or any projects involving significant excavation of molasse materials. These mixtures could be used in the revitalisation of (urban) brownfields, replacement of contaminated soils, for recreational parks in towns or for the vegetation of covers of major roads and transport axes. In addition, the molasse based substrates are tested for trees seedling growth, which could be later used in tree nurseries. The plant species tested in the OpenSkyLab field experiment include climate-resilient varieties that, along with the constructed substrates, could provide important ecosystem services in the future.

Hedgerows are rows of trees, shrubs, and plants growing along agricultural field edges, playing a key role in ecological restoration of agroecosystems, contributing to biodiversity and enhancing environmental resilience. Hedgerows allow to create a beneficial microclimate that can prevent flooding and drought, limit soil erosion, buffer extreme temperatures, and help preserve water quality. Additionally, hedgerows serve as effective windbreaks, protecting crops from wind damage and creating a more favorable environment for growth. They also provide long-term habitats for various species, including wild pollinators and natural enemies of common pests, which are crucial for maintaining ecosystem balance, supporting agricultural productivity and the reduction of the use of pesticides.