The cultivation of white button mushrooms (Agaricus bisporus) generates significant quantities of spent mushroom substrate (SMS), a byproduct traditionally treated as waste despite its nutrient- and organic-carbon-rich composition. The EU-funded project FER-PLAY identified SMS as one of the most promising circular fertilizers (i.e., those produced from waste streams, transforming them into value-added products). Within the project, a life cycle assessment (LCA) and life cycle costing (LCC) analysis of SMS were conducted with a cradle-to-gate-to-grave scope across three European regions, comparing it to a non-renewable mix with equivalent N, P, K, and C inputs. The LCA results reveal substantial environmental benefits of SMS over the non-renewable baseline, particularly in land use, fossil resource depletion, freshwater ecotoxicity and climate change, which together account for 98% of total impacts. Although SMS exhibits higher water consumption, it represents only 2% of total impacts. LCC highlights the critical effects of fresh mushroom substrate composition on yield, economies of scale, and revenue generation. Overall, this study highlights the significant environmental and economic potential of repurposing SMS as a soil improver, offering a compelling case for its integration into agricultural systems as part of a sustainable, circular economy.

The transition to the circular economy (CE) is one of the EU’s current strategic policies to improve its competitiveness and sustainability. While the EU has developed a framework for monitoring overall progress toward the CE, there are gaps in monitoring specific priority sectors, such as the bioeconomy. In order to support industry and policymakers in this sector, this paper presents the application of the BIORADAR’s product circularity monitoring framework to five bio-based fertilizers. The framework is composed of two publicly available indicators: the circular index and the circularity indicator of nutrient; and two new indicator proposals: the biodegradable content and the nutrient slow-release index. Making use of life cycle inventories and supplementary data from the scientific literature, these four indicators were calculated for algae biomass, compost, feather meal, spent mushroom substrate, and wood vinegar. The framework proved to be useful for measuring the circularity at the product level for bio-based fertilizers, especially shedding light on the virgin non-renewable materials consumption, waste generation, biodegradability, nutrient recovery process efficiency, and nutrient release speed. It constitutes the first approach to measuring circularity tailored to bio-based fertilizer. By incorporating it into eco-design, innovation, and managerial decision-making processes, key stakeholders can rely on guiding metrics to support their transition toward higher circularity levels.

Circular bioeconomy is emerging as an alternative framework to produce and consume bio-based resources while reducing damage to nature. But after a decade of development of circular economy (CE) indicators, bio-based products are still missing an appropriate body of product-level measurement tools. This review mapped the CE indicators that have been applied to bio-based fertilizers, packaging, and textiles, with the aim of supporting the further development of decision-relevant tools for product circularity (within the BIORADAR project context). Using a systematic literature review of English-language publications (2016-2025) complemented with widely adopted grey literature and standards, 162 scientific literature documents were retained, and complemented with 16 grey literature documents, resulting in 123 distinct indicators that were extracted, coded, and critically assessed. Although general-purpose and sector-applied indicators together form and extensive body of knowledge, the mapped tools remain uneven in robustness and practical applicability: they often rely on context-sensitive assumptions and data that are not consistently available across firms and regions, and they frequently aggregate multiple circularity features into composite scores that can obscure trade-offs. The indicator set also shows persistent gaps, including limited operationalization of the biological cycle, and weak coverage of key life-cycle stages beyond manufacturing. Overall the main challenge is less the absence of additional metrics than the lack of coordination and transparent, comparable calculation conventions; future work should prioritize a tiered, modular measurement architecture combining a standardized core indicator set with bio-based and sector-specific modules supported by clear data requirements and disclosure rules.

Despite the proliferation of circular economy (CE) indicators and the lack of harmonised measurement conventions, bio-based industries still lack tailored, product-level metrics to guide their circular transition. Three sectors are particularly relevant due to their environmental impacts: fertilisers, packaging, and textiles. This article builds upon indicator mappings by critically assessing how existing indicators account for relevant CE principles and activities, and by developing complementary indicators to address identified gaps. The goal is to propose a product-level circularity monitoring and benchmarking framework tailored for bio-based fertilisers, packaging, and textiles. Following the design research method, existing metrics were characterised, those covering the largest number of CE practices were selected, and complementary indicators were developed to extend the information provided by the original metrics. The framework bridges recurring gaps by incorporating the ratio of biodegradable or compostable materials used in manufacturing, the consumption of virgin materials in packaging manufacturing and textile fibre treatment, and the speed of fertiliser nutrient release. The proposed framework was ultimately feasibility-tested through sectoral applications and industry engagement, demonstrating data availability for computation, interpretive usefulness, and managerial relevance for eco-innovative firms under the tested conditions. Results should be interpreted as comparative screening and monitoring outputs, rather than certification-like estimates.