Search Results (525)

Animal by-products (ABPs), comprising both edible and inedible components, offer significant nutritional, economic, and environmental value. However, their utilization differs markedly across global jurisdictions due to cultural preferences, regulatory frameworks, and technological capacities, which collectively shape consumption patterns and determine integration into food systems or diversion to industrial applications. While consumer reliance on offal remains high in the Global South, driven by tradition, affordability, and nutritional needs, its acceptance in the Global North is markedly lower, often limited by cultural aversion and perceived risks. Drawing from published evidence and primary survey data, this review examines regional consumption trends, industrial utilization pathways, and emerging valorization opportunities for ABPs. Globally, industrial use of ABPs is increasingly shifting toward advanced bioprocessing, integration within circular bioeconomy models, and high-value applications in nutraceutical, pharmaceutical, and bio-industrial sectors. An online cross-sectional survey (n = 358) conducted across Africa, North America, Europe, and Asia revealed strong regional disparities in offal consumption, with higher acceptance in parts of Africa and Asia and more selective use in Europe and North America. Respondents also indicated clear support for non-food valorization pathways, particularly animal feed, fertilizer, and energy production, alongside pharmaceutical and cosmetic applications. These findings align with the literature, where industrial valorization pathways such as collagen and gelatin extraction, rendering, and bioenergy production dominate. This review synthesized the jurisdictional disparities in consumption, regulation, technological capability, and industrial applications while highlighting emerging technological opportunities for high-value valorization. Recommendations emphasize consumer education, regulatory refinement, technological innovation, and sustainable practices to enhance the economic and environmental benefits of ABP utilization within a circular bioeconomy framework. Full article

The large-scale use of compost in arable cropping systems is often limited by the large quantities required to meet the crop’s nutritional needs. Palletization can increase the nutrient density of organic fertilizers and improve their logistical feasibility by reducing storage, transport and application costs. This study evaluated the agronomic and environmental performance of compost pellets derived from pig slurry solids and olive pomace, using them as an alternative nitrogen source for wheat (Triticum aestivum L.) cultivated under Mediterranean conditions. A field experiment was conducted during the 2022–2023 growing season, with four treatments arranged in 24 m² replicated plots: an unfertilized control (C); pelletized compost (PSCOP); fresh pig slurry (PS); and mineral fertilization based on monoammonium phosphate and urea (IN). Excluding the control treatment, all fertilized plots received a uniform nitrogen rate of 150 kg N ha⁻¹. Soil chemical properties and nutrient availability (Pext, NH₄⁺-N and NO₃⁻-N) were evaluated at the beginning and end of the experiment, while wheat yield and grain quality were assessed at harvest. Greenhouse gas (GHG) emissions were monitored throughout the cropping season to evaluate environmental impacts. The results showed that the wheat yields achieved with PSCOP were comparable to those obtained with PS, although they remained lower than those achieved with mineral fertilization. Grain quality was not adversely affected by the application of PSCOP. Furthermore, PSCOP resulted in lower GHG emissions than mineral fertilization, with values closer to those observed in the unfertilized control. These findings suggest that pelletized organic fertilizers such as PSCOP may be a promising way to enhance nutrient circularity and reduce reliance on synthetic fertilizers and maintain crop productivity and limit environmental impact in Mediterranean agricultural systems. Full article

This research evaluated the efficacy of using two types of biochar (non-modified and acidified) from date palm residues (fronds, leaves, pits) as soil amendments for enhancing soil fertility and maize growth. These biochars were produced through slow pyrolysis under oxygen-limited conditions at 500 °C. Our innovative approach was to minimize gas emissions by converting smoke into liquid fertilizer (LS), which was expected to improve seed germination and early plant growth stages. To assess this aim, a completely randomized experiment was conducted under lab conditions, in which 10 maize seeds were placed on double filter papers in Petri dishes and then exposed to seven concentrations of LS (0.0, 0.01, 0.10, 1.0, 10 and 100%, using distilled water for dilution v/v). The LS contains nutrients and bioactive compounds that may enhance seed germination and early plant growth at low concentrations, whereas higher concentrations may cause phytotoxic effects. Results showed that liquefied smoke at 0.1% increased the absolute percentage of maize germination from 75% (control) to 100% and achieved the highest root length of 9.80 cm. Acidified biochars at 5% reduced soil pH from 8.87 to 8.12 and enhanced potassium availability to 87.93 mg kg⁻¹. Conversely, the non-modified biochars contributed to further increases in soil organic matter (up to 1.02%), nitrogen, and phosphorus. In addition, the application of acidified leaf biochar (5%) enhanced maize shoot growth by 133%, chlorophyll content by 39%, and potassium uptake by 110%. This research establishes a scalable approach for converting agricultural waste into climate-resilient resources, effectively addressing soil degradation in arid environments, boosting crop resilience, and furthering the objectives of a circular bioeconomy. Full article

Promoting the agricultural recycling of biogas slurry (BS) is crucial for sustainable development, yet its long-term ecological impacts remain unclear. Through a multi-year field trial in a sugarcane system, this study examined the effects of BS application (0, 3, and 6 years) on the soil properties, bacterial communities, and functional genes for C, N, P, and S cycling. The results revealed distinct two-phase patterns of changes in soil properties, microbial communities, and functional genes. Short-term (3-year) application induced a “disturbance” phase, characterized by significant acidification (pH decreased by 17.91%), a surge in nitrate-N (increased by 757.27%), and a transient decline in bacterial richness. Long-term (6-year) application drove a “functional restructuring” phase, reversing acidification and significantly increasing soil organic matter (29.05%) and total nitrogen (TN) (20.81%). Bacterial richness recovered, and community composition distinctively restructured. Functional gene analysis revealed shifts in gene abundance that transitioned from high abundance in the short term to a new balance favoring processes like N fixation. Co-occurrence network analysis indicated that this functional shift was associated with core microbial modules (e.g., Firmicutes) and changes in soil pH and SOM. This study suggests that, although short-term application causes significant adjustments, sustained and appropriate BS application can ultimately enhance soil fertility and promote a functionally reorganized state by reshaping microbial interaction networks. It presents a microbial ecological basis for the safe and sustainable use of BS in circular agriculture. Full article

Apple pomace represents an important agro-industrial residue with high moisture content and significant environmental burden if improperly managed. This study investigated its thermochemical valorisation into biochar via two processes, followed by comprehensive physicochemical characterization and agronomic evaluation. Elemental analysis revealed carbon enrichment from 47.89% in raw material to 77–78% after the thermal process, evidencing a progressive aromatization. Scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman analysis confirmed a temperature-dependent transition from partially amorphous carbon (400 °C) to more ordered aromatic structures (450 °C), while excessive thermal treatment (550 °C) increased structural defects. ICP-OES revealed an enrichment in thermally stable metals (Fe, Al, Mn) and limited Cd accumulation. Germination assays using Triticum aestivum L. demonstrated that biochar produced at 400 °C significantly improved the germination uniformity and seedling height (14.1 mm), as well as biomass accumulation compared to the control soil sample. The fertilizer addition increased the soluble Na and electrical conductivity (up to 643 µS/cm), potentially inducing transient salinity stress. Soil chemical analysis indicated increased K availability in soils amended with biochar produced at 400 °C, whereas the combination of biochar obtained at 450 °C with fertilizer conducted to elevated concentrations of certain trace metals, mainly Ni and Cr, highlighting the demand for careful monitoring. Overall, the biochar produced at 400 °C yielded to an optimal balance between structural stability, nutrient enrichment, and agronomic performance, evidencing that apple pomace may be a viable feedstock for sustainable biochar production within circular bioeconomy frameworks. Full article

The valorization of industrial waste in agriculture represents a key strategy within the circular economy framework. In this context, the present study aimed to assess the feasibility and potential of fertilizers derived from black mass, a by-product of alkaline battery recycling, as alternative sources of Zn and Mn in citrus cultivation, evaluating their effects on fruit quality and food safety. The experiment was conducted in Pedreguer (Alicante, Spain) in ‘Navelina’ cultivar using Carrizo and C-35 rootstocks, comparing conventional fertilization with black mass-based formulations applied as sulfates (BMSs) and lignosulfonates (BMLSs). The results showed that the evaluated micronutrient sources significantly increased foliar Zn concentrations up to 17.9 mg·kg⁻¹ and Mn concentrations up to 28.1 mg·kg⁻¹, values markedly higher than those observed in the Control treatment (15.20 mg·kg⁻¹ Zn and 11.5 mg·kg⁻¹ Mn). No adverse effects on yield or fruit quality were detected: Average fruit weight remained close to 200 g per fruit, and the proportion of non-marketable fruit did not exceed 2% in any treatment. Regarding food safety, Pb, Cr, and Ni concentrations in pulp and peel were below the maximum levels established by European Union regulations, with maximum values of 0.02 mg·kg⁻¹ for Ni and 0.04 mg·kg⁻¹ for Pb on a dry matter basis, while Cd, Co, and Hg were not detected. Overall, black mass-derived fertilizers enhanced Zn and Mn availability in plants without compromising plant physiology or fruit quality and maintained safe levels of heavy metals. These results support their use as a sustainable alternative for mineral fertilization in citrus orchards and reinforce their contribution to reducing the consumption of virgin raw materials and advancing toward more circular agricultural systems. Full article

The European Environment Agency believes that circular economy strategies could substantially contribute to CO₂ emissions reduction. Therefore, it is necessary that the agro-industrial sector identifies sustainable technologies for side-stream management. The scope of this review was to compare the sustainability of available biological treatments for by-product biomasses and organic waste. A total of 147 studies, all Life Cycle Assessments (LCAs) and Techno-Economic Analyses (TEAs), were selected through PRISMA-ScR methodology, on Scopus and Web of Science, and were bibliographically mapped on VOSviewer (Version 1.6.20) Anaerobic digestion and integrated energy recovery systems were found to be the most environmentally robust options. Integrated biorefineries and multi-product systems have emerged as the highest long-term sustainability potential, especially when process integration and co-product recovery were also implemented. Importantly, the most sustainable systems were found to have required considerable start-up investments. Thus, sustainable deployment of biological treatment technologies was clearly dependent on time-consistent policy frameworks that have been fertile to capital-intensive infrastructures via incentives and fiscal measures and that have embraced circular bioeconomy systems. Finally, this paper has demonstrated that the sustainability of biological treatments has resulted from optimal relationships between biomass characteristics, system boundaries, process integration, and market value of co-product, while no single technology has been sufficient in isolation. Full article

Hydrogels have emerged as promising functional materials for improving water management and nutrient delivery in agriculture, particularly under conditions of increasing water scarcity and declining soil fertility. However, most commercially available superabsorbent hydrogels are based on petroleum-derived polymers, raising concerns regarding their persistence in soils, potential microplastic formation and long-term environmental impact. In response, significant research efforts are being directed toward the development of biodegradable hydrogels derived from renewable biopolymers. This review provides a critical overview of recent advances in hydrogel systems designed for agricultural applications, with a particular focus on biopolymer-based materials. First, the current landscape of hydrogel technologies used as soil conditioners and controlled-release systems for agrochemicals is contextualized, highlighting the limitations of conventional synthetic hydrogels. Subsequently, the main classes of natural polymers explored for hydrogel fabrication, including polysaccharides (e.g., chitosan, alginate, cellulose and starch) and proteins (e.g., gelatin, keratin and soy protein), are analyzed in terms of raw material sources, gelation mechanisms and structure–property relationships. Their performance in key agricultural functions, such as water retention, controlled nutrient release, soil conditioning and enhancement of plant growth, is also discussed. Finally, the review identifies major challenges that currently hinder large-scale implementation, including mechanical stability, degradation behavior in complex soil environments, nutrient release control and economic scalability. By integrating recent progress and outlining emerging research directions, this work aims to support the rational design of next-generation biodegradable hydrogels capable of contributing to sustainable agriculture and circular bioeconomy strategies. Full article

Macroalgal biomass accumulation in eutrophic coastal lagoons represents both an environmental challenge and an underexploited bioresource. This study evaluates the biostimulant potential of Chaetomorpha linum (C. linum) harvested in the Orbetello Lagoon (Italy) on tomato (Solanum lycopersicum) seed germination and early seedling development. Four extraction strategies were investigated: a phytohormone-enriched fraction (PO), a hydroethanolic reflux extract (CLE), a room-temperature aqueous maceration extract (CLWM), and a mild-water-bath aqueous extract (CLWB). Bioactivity was assessed through controlled laboratory germination assays, comparing germination performance, seedling growth traits, and vigor index against an untreated control and a commercial fertilizer. Across the tested conditions, aqueous formulations exhibited the strongest overall effects, with CLWB providing the most balanced response and increasing seedling vigor by approximately 20–30% relative to the control. Collectively, these results support the valorization of eutrophic C. linum biomass into natural, low-input biostimulants for seed priming applications within sustainable agriculture and circular economy frameworks. Full article

Micronutrient addition to soil is crucial for improving crop yield. Within the framework of the circular economy, it is necessary to seek more efficient fertilizers. This would reduce fertilizer consumption while serving as a strategy to mitigate the negative effects of climate change. This study proposes the combined use of a traditional source of a Zn fertilizer (ZnSO₄) together with wood biochar to improve lettuce (Lactuca sativa L.) crop yield. An experiment was designed in which a dose of 8 mg Zn kg⁻¹ as ZnSO₄·7H₂O was added to Cambisol soil, mixed with or without biochar (5%), for lettuce growth. Among other soil properties, Zn bioavailability, microbial biomass, and available water were monitored in the soil, while photosynthetic pigments, Zn content, and biomass production were determined in plants. All treatments increased plant biomass production. Biochar treatments (biochar and biochar/ZnSO₄) increased fresh biomass by 324%, while ZnSO₄ addition resulted in a 158% increase in lettuce yield. This can be due to several factors, such as biochar being a C source, the improvement of soil water content after biochar addition, and the increase in Zn leaf content in all treatments with respect to the control soil. All of these likely had a positive effect on photosynthesis. This is corroborated by the increase in total chlorophyll, chlorophyll, and carotenoids in the treatments with ZnSO₄, biochar/ZnSO₄, and biochar. The application of biochar alone increased this property by more than 168%, with a positive impact on soil quality. Our research demonstrates that it is possible, in some cases, to prepare fertilizers combining ZnSO₄ and biochar, leading to increased plant Zn uptake and improved crop yield. Full article

The effectiveness of poly(isosorbide carbonate) (PIC)—a bio-based polycarbonate synthesized from isosorbide (ISB)—degradation products in complex soil environments remains unverified. In the present study, the agricultural potential of PIC ammonolysis products—comprising urea and ISB—as a nitrogen (N) fertilizer was evaluated in a soil system. A pot experiment was conducted using komatsuna (Brassica rapa var. perviridis) to compare PIC degradation products with commercial urea, a urea and ISB mixture, and a no-N control. Application of PIC degradation products significantly enhanced plant growth, yielding fresh weight and N uptake comparable to those associated with commercial urea. The calculated N recovery efficiency for the PIC degradation products was 50%, falling within the typical range (30–60%) for inorganic fertilizers. Contrary to previous in vitro study results, ISB exhibited no significant biostimulant effect in the soil environment, likely owing to rapid microbial degradation. These findings serve as a preliminary proof-of-concept that PIC degradation products are a highly effective and bioavailable N source. Overall, the results suggest that if scaled appropriately, PIC ammonolysis products could contribute to circular use pathways for this specific plastic. Nonetheless, further studies across a broader range of crops and soils are required to confirm the generalizability of these results. Full article

Insect farming for several purposes, which inscribes itself into circular economy, could become an alternative to traditional agriculture in Europe. Insects are a more sustainable and circular alternative source of protein and fat in food and feeds. The aim of this study is to identify legal barriers to the rearing of insects and marketing of insect-based products. The study focuses on the identification of such barriers to insect rearing and to the production of fertilizers from insect frass. The dogmatic legal method, as well as SWOT and PESTEL analyses, are employed in this research. The two latter methods are used to gain insight into the views held by the industry’s stakeholders. Subsequently, issues within the research field, such as the rearing of insects, their welfare, and the requirements imposed on the feeding of farmed insects, are discussed. Finally, solutions to the identified problems are suggested. The most important strengths of insect farming are its innovative edge and the creation of new products at the EU level. Weaknesses include technological and organizational challenges. Stakeholders attribute high importance to external circumstances, especially economic and social ones. As concluded from this study, the current laws are not optimal for insect farming; however, despite this situation, some changes to the law could facilitate the acquisition of feed for insects or the marketing of some insect-based products. The proposed legal changes aim at lifting the identified barriers to insect farming while still meeting safety requirements and supporting circular economy principles. Full article

Globally, diverse agricultural production strategies have been implemented to address the impacts of climate change, with sustainable farming models emerging as key approaches, particularly in regions affected by environmental degradation. Latin America is especially vulnerable due to its strong dependence on agriculture, pressure on natural resources, and persistent socioeconomic inequalities in rural areas. This study presents a review of sustainable agricultural practices, with particular attention to evidence from Latin America on sustainable agricultural practices as effective strategies for climate change adaptation and mitigation, natural resource conservation, and food security enhancement. Special emphasis is placed on the role of the bioeconomy and the integration of traditional knowledge with modern agricultural management, highlighting their combined contribution to agroecosystem resilience. The review critically examines how sustainable agricultural practices influence soil health, agroecosystem resilience, and the long-term sustainability of agricultural production within a circular economy framework. The findings indicate that practices such as no-till farming, crop rotation, organic fertilization, and integrated soil management significantly improve soil structure, nutrient retention, organic matter content, and soil biodiversity. These practices also reduce soil degradation, enhance resource-use efficiency, and promote carbon sequestration, thereby contributing directly to climate change mitigation. Overall, the results underscore the importance of holistic approaches that integrate traditional practices with technological innovations and highlight the need for further applied research across diverse environmental and socioeconomic contexts, particularly to address adoption barriers among smallholder farmers and to optimize sustainable agricultural strategies at local and regional scales. Full article

Due to the environmental impact and increasing cost of inorganic fertilizers, farmers are exploring alternative fertilization strategies. Tenebrio molitor, otherwise known as the mealworm, is one of the most widely reared insect species for the production of high-quality protein for animals and humans. Mealworm frass (MF), a nutrient-rich byproduct of Tenebrio molitor cultivation, presents a viable option for organic fertilization. To investigate the fertilizer potential of frass, a greenhouse pot experiment was conducted, comparing three levels of MF (MF1, MF2, and MF3 at 20, 40, and 80 g/L soil, respectively), organic compost (ORG), and inorganic fertilizer (FERT). MF gave comparable results to FERT in terms of the measured parameters of vegetation, flowering, and production. ORG also gave comparable results to FERT as far as flowering and production but had significantly lower height compared to it. The MF3 treatment significantly improved the average fruit weight and total yield by 19.56% and 30.81%, respectively, compared to the ORG treatment. The two highest doses of MF outperformed FERT in terms of leaf and soil nutrient status, while MF1 and ORG did not differ from it. Furthermore, MF3 yielded 20% greater fruit weight than MF1. However, MF1 was comparable to FERT in fruit weight, resulting in superior fruit color. These results support reduced-input agriculture by providing data for optimizing soil fertility and nutrient management in crops. The findings of this experiment suggest that MF is a viable alternative to inorganic fertilizers and organic compost for greenhouse cultivation of tomatoes. These results highlight the potential of MF as a circular, bio-based fertilizer capable of maintaining tomato productivity while improving soil fertility under protected cultivation systems. Full article

Tobacco (Nicotiana tabacum) cultivation generates millions of tons of stalk waste annually. This review explores the potential of tobacco stalks as a renewable resource, emphasizing sustainable applications within a circular economy framework, and highlights the key innovative advances. Composting and biochar production from tobacco residues can substantially enhance soil structure, nutrient availability, microbial activity, and heavy metal immobilization, supporting soil restoration and climate-smart agriculture. With 30–36% cellulose and moderate lignin contents, stalks can be converted into bioenergy, biogas, compost, and biopesticides and enable the production of cellulose derivatives. Despite promising results, challenges remain in nicotine detoxification, process optimization, and industrial scalability. Future research should focus on integrated technologies and life-cycle assessments to fully realize the environmental and economic benefits of tobacco waste valorization. Full article