The effects of two digestates split up in liquid and solid fractions were investigated on tomato production. The objectives were (1) to verify if the two digestates different in composition differently affected the growth and the quality of tomato; (2) to assess the effectiveness of the two digestate fractions (liquid and solid) on tomato growth and quality characteristics of the harvested tomato fruit. In short, our results evidenced different effects between the two digestates and also between solid and liquid fractions, suggesting that the type of solid fraction (Uliva or Fattoria) rather than the concentration, or their interaction mainly influenced plant growth parameters. Conversely, the effectiveness of liquid fractions were mostly due to the concentrations rather than to the type of digestate. Results also evidenced positive effects of both digestates on the nutritional values of tomatoes, largely explained by the increase in various health-promoting compounds, including vitamin C, flavonoids, and phenolic compounds. The contemporary increase in these different bio-compounds with a wide range of physiological properties and multi target actions confers to digestate treated tomato a nutraceutical benefit. The use of both fractions of both digestates as fertilizer may represent an effective strategy to obtain, even if in some cases at the expense of growth, high-quality fruit in a sustainable way from an economic and environmental point of view.

The growing global food demand has increased the use of chemical fertilizers, causing environmental issues. Previous studies have often assessed waste-derived fertilizers separately in terms of soil improvement or environmental impact, with limited integration of these aspects across different recycling processes. This study evaluated the effects on soil quality and the environmental impact of fertilizers produced with different percentages of food wastes and different recycling processes. The fertilizers investigated include vermicompost (VC, 70% wood sawdust + 30% food wastes), Compost 1 (C1, 50% wood sawdust + 50% food wastes), Compost 2 (C2, 10% straw + 90% food wastes), and sulfur–bentonite (SBC, 90% SB + 10% food wastes). Six months post-fertilization, vermicompost significantly improved soil properties, increasing soil organic matter from 3.01% to 4.70% (+56%) and total nitrogen from 0.15% to 0.22%, along with an increase in microbial biomass compared to the unfertilized control. Compost treatments also improved soil quality, although to a lesser extent. A Life Cycle Assessment (LCA) was performed across the entire life cycle of the fertilizers. Vermicompost showed the lowest environmental impact, with a global warming potential of 45 kg CO₂ eq ton⁻¹, compared to 93 and 100 kg CO₂ eq ton⁻¹ for C1 and C2, respectively, and 167 kg CO₂ eq ton⁻¹ for SBC. The results evidenced that vermicompost improved soil quality by increasing soil organic matter, total nitrogen, microbial biomass, and biological activity and that it emitted less CO₂ eq, SO₂ eq and PO₄³⁻ during the vermicomposting process, emphasizing its environmental sustainability. The two composts improved soil quality with a moderate environmental impact. SBC positively affected soil properties but with a strong negative environmental impact. From the benefit–cost perspective, the sustainable fertilizer ranking was VC > C2 > C1 > SBC. These findings underscore that these waste management processes represent a possible transition to sustainable fertilizers derived from waste materials to mitigate the environmental degradation associated with the production and use of conventional fertilizers. By adopting these practices, the agricultural sector can boost productivity while maintaining environmental sustainability standards.

Soils represent a critical leverage point for mitigating global warming, acting simultane-ously as major carbon reservoirs and active sources of greenhouse gas emissions under unsustainable management. This review synthesizes current evidence on soil steward-ship practices aimed at reducing carbon emissions and enhancing carbon sequestration. Comparative insights are provided across conventional mineral fertilization, organic amendments, and circular fertilization approaches based on agro-industrial by-products. The review integrates findings from field experiments, long-term trials, and life cycle as-sessment studies to evaluate the effects of different management practices on soil organic carbon dynamics, greenhouse gas fluxes, nutrient use efficiency, and soil biological func-tioning. Special emphasis is placed on the role of waste-derived fertilizers—such as com-posts, digestates, vermicompost—in promoting soil carbon stabilization while reducing the environmental burden associated with synthetic inputs. Evidence consistently indi-cates that soil stewardship strategies grounded in circular economy principles can lower net carbon footprints, improve soil resilience, and mitigate trade-offs between productivity and climate mitigation. By framing soil management within the context of global warm-ing mitigation, this review highlights the multifunctional role of soils as climate regula-tors and underscores the potential of agro-industrial waste valorization as a scalable pathway toward climate-smart and low-emission agricultural systems.

Agricultural soils play a dual role in the climate system, acting both as carbon sinks and natural sources of greenhouse gas emissions, which may be intensified under unsustainable management. However, the comparative effectiveness of different soil management strategies, particularly organic amendments derived from agro-industrial residues, remains insufficiently clarified. This review aims to critically synthesize current scientific evidence on soil stewardship practices for mitigating greenhouse gas emissions and enhancing soil carbon sequestration. The analysis is based on a structured review of peer-reviewed literature published over the last decade, including field experiments, long-term trials, and LCA studies. Comparative insights are provided across conventional mineral fertilization, organic amendments, and circular fertilization approaches based on agro-industrial by-products. The results indicate that organic amendments such as compost, digestate, and vermicompost generally increase soil organic carbon stocks (up to +40% in long-term systems) and can reduce greenhouse gas emissions and carbon footprint compared with mineral fertilization, although responses vary depending on soil, climate, and management conditions. The review evaluates the effects of different management practices on soil organic carbon dynamics, greenhouse gas fluxes, nutrient use efficiency, and soil biological functioning. Special emphasis is placed on the role of waste-derived fertilizers—such as composts, digestates, and vermicompost—in promoting soil carbon stabilization while reducing the environmental burden associated with synthetic inputs. Evidence consistently indicates that soil stewardship strategies grounded in circular economy principles can lower net carbon footprints, improve soil resilience, and mitigate trade-offs between productivity and climate mitigation. By framing soil management within the context of global warming mitigation, this review highlights the multifunctional role of soils as climate regulators and underscores the potential of agro-industrial waste valorization as a scalable pathway toward climate-smart and low-emission agricultural systems.

Soil degradation and organic matter depletion threaten the sustainability of Mediterranean agroecosystems, highlighting the need for effective and sustainable soil restoration strategies. This study evaluated the short-term effects of composts and vermicomposts derived from chestnut sawdust and food waste on soil functionality and broccoli quality under field conditions using a multi-indicator assessment framework. Six fertilization treatments, including composts, vermicomposts, horse manure, mineral NPK fertilization, and an unfertilized control, were tested in broccoli-cultivated plots. Organic amendments significantly improved soil chemical, biochemical, and biological properties compared with mineral fertilization and the unfertilized control. Vermicompost 10/90 (10% sawdust:90% wet waste) produced the strongest effects, increasing soil organic carbon and organic matter by about 85%, cation exchange capacity by 45%, and dehydrogenase activity by 83% compared with the unfertilized control. Compost and vermicompost treatments also enhanced microbial biomass carbon, enzymatic activities, and QBS-ar values, indicating improved soil biological quality and microarthropod diversity. Broccoli quality was significantly influenced by fertilization regime. Vermicompost 10/90 increased vitamin C by 154%, vitamin E by 54%, total proteins by 18%, and total carbohydrates by 17% compared with the unfertilized control. Organic amendments also enhanced total phenolics, flavonoids, and antioxidant activity relative to NPK and control treatments. Principal component and correlation analyses revealed strong positive relationships among organic matter accumulation, microbial activity, enzymatic processes, soil biodiversity, and crop nutritional quality. Overall, the integrated multi-indicator approach demonstrated that waste-derived organic amendments improve soil functionality and crop quality simultaneously, supporting their use as sustainable tools for circular and resilient Mediterranean agricultural systems.