Sustanainable growing substrates based on local wood resources

The proposed research project intends to develop a new approach for the increased use of regional wood raw materials to produce horticultural growing media. The aim is to modify wood fibres by means of a thermal or thermo-hydrolytic process to increase their stability towards microbial conversion. This is expected to inhibit the immobilisation of nitrogen (N), which has previously made the N-dynamics in wood-based growing media hard to predict. During the modification process, as little wood substance as possible should be lost (high yield) and potential by-products should be utilizable as valuable resources. The project aims to develop an energy- and cost-efficient process that also allows tapping new sources of raw materials, such as deciduous trees from short-rotation plantations or waste from fibreboard and particleboard production. Thus, it will contribute to securing the supply and reducing the costs of raw materials in the production of peat-reduced substrates. In addition to the process- and product-development, the project will refine methodological approaches for a reliable assessment of biological, chemical and physical properties of wood fibres and optimise irrigation control for substrates rich in wood fibres. The thermally stabilised wood fibres are supposed to be free of growth-inhibiting substances and they should make up a proportion of ≥ 50 % (v/v) in the substrates. Consequently, the use of peat as a substrate raw material may be significantly reduced or completely avoided, if other organic materials such as compost are added. The new wood fibre substrates are expected to be suitable for growing a wide range of pot and container crops.