Growth of Young Forest Trees in Peat-Free and Low-Peat Soils

Greg Howard
5th May, 2024

Growth of Young Forest Trees in Peat-Free and Low-Peat Soils

Image Source: Natural Science News, 2024

Key Findings

  • In Finland, scientists tested alternatives to peat for growing tree seedlings, aiming for more sustainable forestry
  • Mixes with at least 50% peat supported growth similar to pure peat; however, pure peat yielded the tallest seedlings
  • All alternative growing media tested could produce marketable seedlings, but adjustments in nursery management are needed
In the quest for more sustainable forestry practices, scientists from the Natural Resources Institute Finland (Luke) have explored alternatives to the traditional use of peat as a growing medium (GM) in the cultivation of tree seedlings[1]. Peat, which is a staple in the production of seedlings, particularly in Nordic countries due to its favorable properties for plant growth, is also a source of carbon emissions when extracted and used. Its reduction or replacement with more environmentally friendly materials is a significant step toward reducing the carbon footprint of forestry operations. The study focused on assessing the viability of different peat-reduced and peat-free GMs for growing key tree species crucial to Nordic forestry. These species included Scots pine, Norway spruce, silver birch, Russian larch, and common alder. A variety of materials were tested, including low-humified Sphagnum peat (as a control), harvested Sphagnum moss, wood fiber, cow manure digestate from biogas plants, and compost made from common reed. The seedlings were cultivated both under controlled greenhouse conditions and in commercial tree nurseries to simulate real-world applications. The research revealed that GMs containing at least 50% volume of peat could support growth comparable to that achieved with pure Sphagnum peat. While all alternative media tested were capable of producing marketable seedlings, there were some trade-offs, such as smaller seedling sizes and the need for tailored adjustments in growing management. These adjustments pertain to modifying the physical and chemical properties of the GMs, as well as adapting fertigation (the process of delivering fertilizers along with irrigation water) and other management procedures to suit the new materials. This study builds on previous research[2], which investigated the use of recyclable waste materials like compost, biochar, and ash to improve plant growth on reclaimed mine tailings. The addition of compost as a nitrogen source was found to be beneficial for plant establishment during the initial growing seasons. Specifically, a mixture of till, compost, and a certain type of biochar (derived from sewage sludge and woodchips) provided the best biomass growth. This earlier study[2] also identified that certain types of ash could promote the height growth of pine seedlings. The findings from Luke's research suggest that there are indeed viable alternatives to peat that can be used in tree seedling production. However, the transition to these new materials is not without its challenges. For instance, the economic feasibility and environmental impact of these alternative GMs still require thorough evaluation. Additionally, the success of seedlings grown in these new media after being transplanted into the field needs to be assessed to ensure that the long-term outcomes of using peat alternatives are positive. The significance of this research lies in its potential to provide a blueprint for nurseries to move away from peat-based GMs, thereby contributing to a reduction in peat extraction and its associated environmental impacts. By demonstrating that peat-reduced and peat-free GMs can yield marketable tree seedlings, the study offers a promising avenue for more sustainable forestry practices. However, the implementation of these alternatives will require careful consideration of the adjustments needed in nursery management practices to maintain the quality and viability of the seedlings. In conclusion, the research conducted by the Natural Resources Institute Finland represents a step forward in the effort to make forestry more sustainable. By exploring peat-reduced and peat-free growing media, the study opens up possibilities for reducing the reliance on peat and mitigating its environmental consequences. With further research into the economic and environmental benefits, as well as the practical implications of using these alternative GMs, the forestry industry may be able to adopt more eco-friendly practices without compromising the quality of its seedlings.

AgricultureSustainabilityPlant Science


Main Study

1) Growth of Nordic container forest tree seedlings in some peatless and peat-reduced growing media

Published 4th May, 2024

Related Studies

2) Effects of compost, biochar and ash mixed in till soil cover of mine tailings on plant growth and bioaccumulation of elements: A growing test in a greenhouse.

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