Institut für Pflanzenbau und Bodenkunde
The horticultural sectors need professional solutions to master the urgently needed ecological switch to peat-free or peat-reduced growing substrates. The ToPGa project thus focuses on investigating and evaluating the effects of the use of peat-reduced substrates. Only with the help of such a comprehensive examination can recommendations be given to the practice for switching to peat-reduced substrates. In the project, researchers from various fields are working together with the aim of working on the various problem areas of the use of peat-reduced substrates and developing interdisciplinary approaches to reducing the use of peat for all horticultural sectors.Both the optimisation of crop security in the use of substrate raw materials such as wood fibre, coconut, substrate compost etc. and the investigation of new substances that have so far been used little or not yet in horticultural growing media are therefore urgently needed. Currently, peat substitutes used on a large scale, such as coniferous wood fibres, may decline in the future due to forest restructuring; coconut is criticised for socio-ecological reasons. New substances, which are available in large quantities, are needed in order to provide the quantities of high-quality peat substitutes required in the future. For socio-ecological reasons, renewable peat substitutes from regional cultivation are to be preferred. Therefore, as an alternative to coconut fibre, the fibre nettle would be interesting as a peat substitute. The fibre nettle is a variety of the large stinging nettle (Urtica dioica L.), whose fibre content has been increased by breeding. Within the framework of the project, the JKI Institute of Crop and Soil Science (1) is investigating the sustainable cultivation and yields of three newly bred fibre nettle clones within an already established agroforestry system and in the "open field". In contrast to other renewable raw materials (e.g. typha) which can be used as peat substitutes, the cultivation of nettle fibres can take place on large areas and delivers a high fibre yield per unit area. The resilient cultivation in the agroforestry system favours the nettle (wind protection, shading); an additional incentive for farmers is provided by the wood production and the subsidy of tree strips. (2) Nettles are nitrogen-intensive plants. The C:N ratio of the plants is to be optimised via various N fertiliser levels in order to reduce the risk of N immobilisation in the growing medium. Wood fibres from the tree strips (poplars) of the agroforestry system are to be combined with the fibres of the nettle according to the desired characteristics of the substrate. (3) An estimation of the potential of nettle cultivation will be carried out with regard to site conditions and site requirements.
Federal Ministry of Food and Agriculture
