Constructed Technosols are key to the sustainable development of urban green infrastructure

Abstract. With the rise in urban population comes a demand for solutions to offset environmental problems caused by urbanization. Green infrastructure (GI) refers to engineered features that provide multi-ecological functions in urban spaces. Soils are a fundamental component of GI, playing key roles in supporting plant growth, infiltration, and biological activities that contribute to maintenance of air and water quality. However, urban soils are often physically, chemically or biologically unsuitable for use in GI features. Constructed Technosols (CT), consisting of mixtures of organic and mineral waste, are man-made soils designed to meet specific requirements and have great potential for use in GI. This review covers (1) current methods to create CT adapted for various GI designs and (2) published examples where CT have been used in GI. We address the main steps for building CT, the materials and which formulae that should be used to design functional CT, and the technical constraints to using CT for applications in parks, streetside trees, stormwater management, urban farming, and abandoned land. The analysis suggests that the composition and structure of CT should and can be adapted to available wastes and by-products and to future land use and environmental conditions. CT have a high potential to provide multiple soil functions in diverse situations and to contribute to greening efforts in cities (and beyond) across the world.