Stockholm soil SH150 is made up of 90-150 mm clean stone combined with a 1:1 mix of enriched biochar and compost (15% volume). This method is well established and evaluated in Stockholm.
Stone must be a clean aggregate, angular to sub-angular in shape. This ensues optimal void space.
Biochar and Compost
Biochar improves composting performance, humification, microbial diversity and activity, reduces greenhouse gas emissions, and immobilizes potentially toxic metals and organic pollutants.
Biochar's porous structure also allows it to remove a wide range of pollutants from stormwater.
The pH profiles of biochar produced by different methods (pyrolysis or hydrothermal carbonization) and different feedstocks vary significantly.
Compost can hold more water with biochar which improves plant growth.
Biochar needs to be activated with the compost for a minimum of one month.
Read more about Structural Soil.
