Sidestream materials show potential as top-dressed soil improvers for peatland forests

Area of Science:

• Forestry
• Soil Science
• Environmental Science

Background:

• Peatlands are crucial ecosystems for forestry, but often require soil amendments for optimal seedling growth.
• Industrial and agricultural byproducts present potential sustainable sources for soil ameliorants.
• Evaluating the efficacy and safety of these sidestream materials is essential for their application in forestry.

Purpose of the Study:

• To assess the physical and chemical properties of industrial and farming sidestream materials.
• To evaluate the impact of these materials as top-dressing soil ameliorants on downy birch and Scots pine seedling growth in sphagnum peat.
• To determine the potential for using these sidestream materials in peatland forest fertilization.

Main Methods:

• Selected sidestream materials (wood fly ash, filter cake waste, mine tailings sand, cow manure digestate/reject) were characterized.
• Materials were applied as top-dressing to unfertilised peat in pots at rates comparable to Finnish peatland forest fertilization (2-6 t ha⁻¹).
• Seedling growth, percolate water pH, and foliar nutrient content were monitored over one growing period in a greenhouse experiment.

Main Results:

• Percolate water pH remained below 4 in most treatments, and below 3 with filter cake, but did not impair seedling growth.
• All tested sidestream materials supported seedling growth at least as well as the unfertilised control.
• Cow manure-derived additives significantly enhanced seedling growth, evidenced by increased foliar nitrogen and phosphorus levels in birch seedlings.
• No harmful concentrations of heavy metals were detected in the applied materials.

Conclusions:

• All evaluated industrial and farming sidestream materials demonstrate potential as effective soil improvers for forested peatlands.
• Cow manure digestate and liquid reject show particular promise due to their nutrient content, significantly promoting seedling growth.
• The use of these sidestream materials offers a sustainable approach to enhancing forest regeneration and growth on peat soils.