Testbeds for multi-functional biochar based soil mixtures

Last changed: 30 May 2023

Research on sustainable soil, water and plant systems for urban outdoor environments is part of the activities at SLU. The aim for this project is to develop knowledge about what multi-functional and ecosystem friendly urban plant beds should consist of that leads to a good growth despite the increasing stress urban trees are exposed to in the ongoing climate change.


Both in Sweden and internationally, there are experiments with new kinds of multifunctional plant beds to promote good growth and to test new technical solutions for storm water management and carbon storage. From best practice, it seems that a mixture of approx. 80% crushed stone and 20% biochar and compost is a good starting point.

The project

In the testbeds at Ultuna, one and the same clone-propagated linden tree (Tilia x europaea 'Kristina') grows in eight different soil mixtures. The aim is to investigate how different plant substrates affect root development and vegetative growth. We measure changes in temperature and soil moisture in substrates with different permeability and infiltration capacity.

We document how different soil mixtures affect growth and capture stormwater. The ambition is to describe something of the ecological interplay, mainly how fungi and mycorrhiza develops in the containers over time.

The test beds consist of about one cubic meter big containers, manufactured by the Research Institutes of Sweden (RISE) at Ultuna.

The project is sponsored by soil suppliers Bara Mineraler, Biokolprodukter, Hasselfors Garden and Rölunda. The trees are sponsored by Essunga plant nursery.

Meeting point

The test beds also function as a meeting point for researchers, teachers, students, planners, consultants and the business community. In this way, we create opportunities for dialogue and exchange of experiences regarding the potential of using biochar-based substrates in a larger scale connected to sustainable and climate change adapted urban development.


Project leader

Petter Åkerblom, Senior Lecturer, Division of Landscape Architecture, SLU

Project participants

Karin Blombäck, Research Leader, Dept. of Soil and Environment, SLU
Read more about Karin Blombäck on her CV page 
Send an e-mail to: karin.blomback@slu.se

Sofia Eskilsdotter, Lecturer, Division of Landscape Architecture, SLU
Send an e-mail to: sofia.eskilsdotter@slu.se

Örjan Stål, Assoc. Lecturer, Expert on urban tree establishment and tree care, Division of Landscape Architecture, SLU
Send an e-mail to: orjan.stal@slu.se

John Lööf Green, Coordinator at Real Estate Office Ultuna, SLU 
Send an e-mail to: john.loof.green@slu.se

Projekt time