The cultivation of flowers, vegetables, and fruit in alternative growing media, known as substrates, is rapidly increasing worldwide. In colder climates, this typically occurs in greenhouse production, while in warmer climates, plants can be grown in pots that are only protected from rain and wind. The yields per unit area are significantly higher than in open-field cultivation, and production can continue year-round.
Much of the food on store shelves today is produced in substrate. The substrate can be based on various raw materials, with peat and crushed coconut husks being the most commonly used. The problem is that these substrates are usually only used once. This is because fungi and other pests can establish themselves in the substrate during cultivation, potentially ruining future crops. Sterilization and reuse of substrate will be one of the most important environmental measures for greenhouse production worldwide:
1. Sustainability, Stability and Environmental Considerations
- Reduced peat extraction: Peat is a non-renewable resource that takes thousands of years to form. Large amounts of peat are used in greenhouse production, but its extraction releases CO₂, contributing to climate change. Reusing peat can drastically reduce the demand for new peat.
- Less waste: Used substrate is often discarded or treated as waste. If it is sterilized and reused, the amount of waste can be significantly reduced.
- Compliance with future environmental regulations: Several countries are considering restrictions on peat use in agriculture and horticulture (e.g., the UK plans to phase out peat in gardening products). Reuse can be part of the solution to meet new regulations.
- Less transportation and freshwater use: Coco coir is produced in distant regions and must be transported over long distances. In turbulent times, international transport becomes complicated and often costly. Additionally, large amounts of freshwater are used during production, freshwater that could have been used by local populations.
2. Economic Benefits for Growers
- Cost savings: Buying a new substrate is expensive. If growers can use the same substrate multiple times without losing quality, they can save significant amounts of money. This could also benefit consumers through lower prices.
- Production stability: Importing substrate is vulnerable to supply chain issues. Reusing existing substrates gives growers greater stability and predictability.
3. Proven Effectiveness
- Steam treatment eliminates diseases: Steam sterilization is a well-known method for eliminating fungi, bacteria, and nematodes from soil and substrate. Studies show that plants grown in steam-treated substrates often have the same growth quality as those grown in new substrates.
The reuse of substrate will be an important step toward sustainable agriculture. It will help reduce greenhouse gas emissions, lower costs for growers, and ensure compliance with stricter environmental regulations.
SoilSteam is working with Europe’s leading research center for greenhouse production, Proefcentrum Hoogstraten, to document that steam treatment of substrate is a future-oriented solution. The first machines adapted for substrate recycling will be ready for delivery in 2025.