Modified pulpwood fibres to replace peat as a sustainable growing medium in professional horticulture (PeatFree)

Environmental and political concerns demand substrates alternative to peat that are more environmentally friendly. A possible option is to use the lignocellulosic, wood pulp residues, after 95 % of the hemicellulose has been removed by a non-chemical process and used as animal feed. Within PeatFree, detailed studies will be conducted by NMBU in close cooperation with Norsk Skogsmelasse AS, LOG and four of the best Norwegian growers within floriculture, vegetables, nursery stock and berries. Norsk Skogsmelasse plan to build a factory for production of hemicellulose, by use of a patented process, that will be used in feed production at Fiskå Mølle. The side stream comprised of lignocellulosic materials that are the proposed materials to be used in the Peat Free plant growing media and preliminary results indicate this would be a good base as a growing medium (NFR project Miljøvennlig 296606). Physical, chemical and the biological properties of this wood fiber will be analyesed and adding of fertilizer, lime and bio-active materials to meet the standards set for best horticulture substrate. In this wood fibers it will be little easily available carbon that could stimulate microbial activity that would require additional fertilization for optimal plant growth. This makes it possible to grow in almost 100 % wood fibers, without additional supply of fertilizers, which is the case by use of ordinary wood fibers. This will hopefully also give a slower degradation of the fibers, that is a great advantage for long crops. In addition, the potential of a value-added product will be tested for root health for selected horticultural crops in addition to LCA analyses. Further, the experimental outcomes will be validated with commercial greenhouse level experiments in close cooperation with the industry partners. If successful, expected product from this project will replace the use of peat as horticultural substrate in Norway and subsequently in Europe.

Due to environmental impacts of using peat, there is societal and political pressure to develop more sustainable horticultural growing media. A possible option is a lignocellulosic fibrous material from pulpwood residues, after hemicellulose has been removed in a nonchemical process to be used as animal feed. The remaining product represents a renewable organic material that is less easily decomposed and thus less likely to immobilise nitrogen in plant production compared to ordinary wood fibre. Norsk Skogsmelasse AS plans to produce hemicellulose for feed production at an industrial scale at Fiskå, where the side stream of lignocellulosic material is estimated to amount to about 500.000 m3/yr. Researchers in plant and soil science from the Norwegian University of Life Sciences (NMBU) will, in close cooperation with the industry, use this material to develop horticultural substrates that can replace peat in professional horticulture. They will determine physical, chemical and biological properties with respect to stability and support for healthy plant production and consider the use different additives, such as biochar, to develop strategies for reduced chemical pest control. Four of the best Norwegian professional growers representing diverse plant production profiles will test the substrate blends to document the quality and give feedback to the researchers for further development. Both environmental and economic sustainability will be evaluated in an international cooperation. The PeatFree proposal is divided into seven work packages (WPs) where close cooperation will effectively build competence and allow communication both between project partners and towards the greenhouse industry and society in general. One Post-Doctoral fellow and one PhD-student as well as MSc students will participate in the project.