Using constructed soils for green infrastructure – challenges and limitations

Abstract

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 multiecological 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 the maintenance of air and water quality. However, urban soils are often physically, chemically, or biologically unsuitable for use in GI features. Constructed Technosols (CTs), 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 CTs adapted for various GI designs and (2) published examples in which CTs have been used in GI. We address the main steps for building CTs, the materials and which formulae should be used to design functional CTs, and the technical constraints of using CTs for applications in parks and square lawns, tree-lined streets, green buffer for storm water management, urban farming, and reclaimed derelict land. The analysis suggests that the composition and structure of CTs should and can be adapted to available wastes and by-products and to future land use and environmental conditions. CTs 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.

Urban areas, human health and technosols for the green deal

“…Soils are a fundamental component of green infrastructure (Deeb et al, 2018 ), and a none common solution for the EGD urban needs (Deeb et al, 2020 ) could be use of wastes to construct new urban soils (Li et al, 2018 ; Pruvost et al, 2020 ), as Technosols. In fact, urban soils can be made of exogenous materials and due to disturbances of human activities; they have lost their natural functions, becoming Technosols (IUSS 2015 ).…”

“…Most of the authors agree on its composition (artifacts, such as, wastes, materials, soils), and its human origin; however, the possible usefulness or the functional services Technosols provide are not mentioned. An initial approach to define Technosols in terms of their functional viability recently provided, in which the need to be suitable for the development of vegetation is attributed (Deeb et al, 2020 ).…”

“…Among issues addressed by authors (Baragaño et al, 2020 ; Charzyński et al, 2017 ; Rees et al, 2019 ) mainly evaluate quality of urban soils (soil sealing or compaction, contamination and carbon sequestration). As well, formulate new Technosols for soil improvement by using municipal waste, for instance, (Barredo et al, 2020 ; Deeb et al, 2020 ; Ugolini et al, 2020 ), which can be used for city revegetation (rooftops, parks, brownfield reclamation).…”

A Geochemical and Agronomic Evaluation of Technosols Made from Construction and Demolition Fines Mixed with Green Waste Compost

“…Several studies have successfully constructed technosols with favourable soil-like properties that are able to perform a wide range of functions from plant growth and decorative greening to active sequestration of CO 2 from the atmosphere [7][8][9]. Indeed, one of the most recent analyses on the topic of constructed technosols stated that such substrates produced from a wide variety of waste materials have a high potential to provide multiple soil functions in urban areas [10], with applications not limited to greening, but also including the growth of food crops [11]. An additional advantage of urban applications arises when technosol components can be sourced locally to their end usage, avoiding long-distance transportation of wastes for disposal by other means [12], or similar transportation related costs incurred securing adequate supplies of soil ex-situ.…”

“…Therefore, a clear abundance of C&D-fines and organic waste base materials exist that could be utilised to create technosols. Such substrates have been variously produced and tested previously, but generally these have consisted of waste materials blended with extant soil [10,19,20], with few studies testing technosols produced without the input of geogenic soils [11]. Therefore, there is a paucity of detailed study of technosols produced solely from wastes in terms of mineralogy, geochemistry and plant growth performance, and it was thus deemed pertinent to conduct the following study.…”