This case study focusses on the use of forest biomass for energy production and the subsequent recycling of wood ash in North Karelia, Finland.

VALERIE theme covered:
 6. Recycling and smart use of biomass and food waste, in particular waste generated during primary production ►

In North Karelia, generating energy from forest based biomass produces large quantities of wood ash. Some of the wood ash is used as fertiliser in forestry and also in road construction. However, the majority of ash is regarded as waste with power plants and other industrial facilities incurring large disposal costs.

Location: North Karelia, eastern Finland
Main land use: forestry
Stakeholders: Forest owners, forest owner organisations, logging entrepreneurs, forest industry, heat entrepreneurs, energy producers, ash processors, researchers, decision makers and politicians
Key issues:
o    Environmental impact of wood ash recycling (e.g. heavy metals, aluminium)
o    Ecosystem services
o    Use of ash for construction
o    Achieving sustainability in the forest based bioenergy supply chain
o    Ash recycling best practice
o    New spreading systems
o    Impacts of using wood ash fertiliser on mineral soils

Case study updates:
• A kick off meeting was held in summer 2014 with a representative cross-section of stakeholders from forest owners to industry. The main obstacles and research needs were identified along with additional stakeholders.

• A first workshop was held in mid-January 2015 in Joensuu with a representative cross-section of stakeholders from forest owners to industry; including many new stakeholders. Positive feedback was given on the VALERIE innovation factsheets reviewed, although with a recommendation to include more practical details. Testing ash fertilisation on mineral soils was identified as a suitable topic for a field trial.

• At the VALERIE project meeting held in Finland, June 2015, participants took part in a field trip learning more about sustainable forestry in Finland and the case study on Sustainable Forest Biomass, based in Joenssu. See a presentation of the event here.

Field trials:
• Issues to be addressed in the field trials:
o    Impacts of using wood ash fertiliser on mineral soils
o    The barriers, benefits & feasibility of using wood ash as a fertiliser

• Use of wood ash on nutrient poor mineral soils will lead to a better recycling of wood ash and may have positive effect on forest growth and income for the forest owner. The trial aims are:
o    To test wood ash fertilization in forests on nutrient-poor mineral soil
o    To collect information about the barriers, the benefits and the feasibility to use wood ash as a fertilizer

• Trials are planned to start in 2016.

• The case study held a field trip on 8th June 2016. A group of stakeholders and researchers spent a rainy Wednesday in the North Karelian forests discussing the use of recycled wood ash from various perspectives. There was a demonstration of spreading wood ash for use as a fertilizer and people could witness with their own eyes the positive influence of wood ash on forest growth. At the end of the day it was a surprise to see that even a cycle path can be made from wood ash!


With wood ash as a fertiliser


Without wood ash as a fertiliser


 • Details of the field trip have been posted to Facebook and published as a newspaper article (in Finnish) in the Karjalainen, the newspaper from North Karelia. A short version of the newspaper article can be found on the web at:

Contact: Saara Lilja-Rothsten; This email address is being protected from spambots. You need JavaScript enabled to view it.