Planting Urban Trees with Biochar
by Bjorn Embrén
Urban trees face various challenges which frequently lead to high tree mortality, shorter lifespans and increased maintenance cost. To improve tree health and survivability the Swedish capital Stockholm has been testing and refining the use of structured soils and biochar for nearly 10 years. These structured soils consist of gravel mixed with smaller soil amendments such as peat, sand, clay, lava and more with great success: biochar. In some cases 6 year old trees planted in structured soils with biochar were five times larger than 30 year old trees planted using more traditional urban tree planting techniques.
Over the past years, a variety of different soil amendments, biochar & stone mixtures have been tested for planting urban and suburban trees, bushes, perennials and grasses in Stockholm. The Biochar Journal discussed the various experiences and recommendations with Bjorn Embrén who heads up the City of Stockholm’s Landscaping Department.