At conventional construction sites, the removal of soil and other excavated materials causes enormous mass movement, with a significant climate impact and contribution to global CO₂ release. This study aimed to generate a Circular Soil concept for reusing excavated materials by creating engineered soils for landscape construction at large building sites. Engineered soils act as a substitute for natural soils and fulfill vital technical and soil functions when installing an urban green infrastructure (GI). In a field study, the vegetation performance on engineered soils was evaluated to establish a methodological approach, to assess the applicability of the Circular Soil concept. First, the technical specifications (grain-size distribution) were modeled for intensive green roof and turfgrass applications. Then, the soil components were optimized, mixed, installed and tested for greenery purposes, focusing on plant growth performance indicators (vitality, projective cover ratio and grass-herb ratio) to assess the vegetation performance. The results showed that the engineered soils match the performance of the reference soil alternatives. In conclusion, the Circular Soil concept has a high potential to contribute considerably to sustainable on-site soil management and the circular economy. It can be applied on a larger scale for urban GI development and sustainable resources management in the landscaping and construction sector.

Although urban soils are strongly influenced by human activities, they provide a wide range of Ecosystem Services (ES) as long as they are not sealed off. This is a major sustainability issue as the loss of soil functions directly impacts ES and further on the possibility to adapt to the effects of the climate crisis. Green Infrastructure (GI) measures can be utilized to restore previously covered soil surfaces and compensate for lost soil functions. We conducted a systematic literature review to investigate the extent of peer-reviewed publications on GI measures in (peri-) urban areas covering soil-related ES. After identifying the relevant publications (n = 284), we generated an overview of the annual, spatial, and thematic distribution of the publications. Then, we employed an extended content analysis of the published focus topics to assess the representation of soil-related ES provided by GI. The content analysis revealed that the representation of soil-related ES in GI measures focused heavily on the contribution of soil to stormwater management. Detailed assessment of the interconnection of GI measures with key soil-related ES were missing. So far, the assessment of the loss of soil-related ES is not covered extensively in GI research publications.

Summary: In times of climate change and increasing societal needs, the pressure on land is unprecedented. Sustainable soil and land use management is only achievable if stakeholders from sectors concerned work together. The aim of the project INSPIRATION (Integrated spatial planning, land use, and soil management esearch action) was the integration of science and interdisciplinary research fields to develop a strategic research agenda (SRA) for sustainable land use and soil management in Europe. This article presents the Austrian perspective and contribution to the SRA, highlights the findings of the project, and identifies the most urgent research needs addressing key societal challenges. The project followed a bottom-up, multi-stakeholder approach to enable an evidence-based collation process of interdisciplinary research needs. Through expert interviews, reviews of state-of-the-art documents, and public involvement, six key research topics of the most pressing research needs in Austria were identified. This Austrian contribution to the SRA is characterized by the need for a communication frame and knowledge transfer among research, policy, and society. A compatible knowledge transfer is pivotal to establish an understanding of shared responsibilities among all stakeholders.

Green Infrastructure measures such as seepage troughs are an integral part of sustainable urban rainwater management. In Austria, seepage troughs are currently almost exclusively produced with a 30 cm thick active soil filter passage made of topsoil. A standard seed mix is used as vegetation, which usually consists of only three different turfgrass species. During a three-year trial, engineered soils with improved properties (increased water storage capacity, infiltration rate and pore volume) were tested for their suitability as seepage troughs compared to topsoil. In addition to the standard turf seed mix, a flowering turf seed mix (34 species) and flowering meadow seed mix (53 species) were applied. The engineered and reference soils were analyzed for infiltration rate, vitality, cover ratio and inflorescence. The results were further assessed with the evaluation chart showing quantitatively the suitability of the tested soils for rainwater management. The investigations showed that engineered soils in combination with flowering meadow seed mix lead to the best results. Therefore, this type of vegetation for seepage troughs is recommended for future applications. The reference alternatives cannot be recommended.

Equations for calculating evapotranspiration in technical soils show great differences regarding their results. Causes are the different climatic conditions and vegetation specifics during their development. Every equation of evapotranspiration only delivers 100% correct results if it is used under the same climatic condition as it was developed in. To determine the evapotranspiration, the loss of weight of different technical soils and plants was measured in a test series on load cells in a climate chamber. The result of these test series is the development of an easy-to-use equation. An equation for calculating evapotranspiration at any temperature is possible while using a polynomial correlation. To determine the evapotranspiration rate (in mm/m² per 24 h), only temperature, vegetation type, and technical soil have to be defined to obtain an output of evapotranspiration in mm/day. Using the well-known equation by Makkink, evapotranspiration in technical soils is 0.12 mm/day, whereas the newly developed equation calculates (1) 2.59–5.58 mm/day for the variant with no vegetation, (2) 3.15–4.00 mm/day for Sedum floriferum, (3) 4.40–4.55 mm/day for Geranium x cantabrigiense. The application of this equation will help to determine the evapotranspiration in chosen technical soils (used in the sector of rainwater management) with or without vegetation.