By integrating waste valorisation and nutrient management perspectives, this session aims to bring together researchers, early-career scientists, and practitioners to exchange knowledge and advance sustainable soil management in circular agroecosystems. Emphasis will be placed on initiatives that translate scientific advances into tangible practices for sustainable agriculture and resilient agroecosystems.
Within this broader context, the session also addresses nutrient cycling and soil remediation through the use of organic amendments and chars, including biochar. These materials can contribute to improved nutrient retention and use efficiency, reduced nutrient losses and emissions, and enhanced soil–water–plant interactions, depending on feedstock, processing methods, application rates, and site-specific conditions.
This session aims to address:
• Field and lab experiments on productivity, nutrient efficiency, and soil health.
• Remediation of polluted soils and aquatic systems.
• Modeling nutrient cycling, pollutant dynamics, and amendment behavior.
• Life cycle assessment and sustainability studies.
• Effects of feedstock, processing, and transformation methods (composting, anaerobic digestion, pyrolysis, etc).
• Investigations on emissions, volatilization, and leaching.
• Agro waste valorization for a sustainable agriculture.
The session aims to create a meeting point for researchers, early-career scientists, and practitioners from academia, research centers, and industry to present recent results and exchange knowledge on waste management, recycling, and valorization strategies. Emphasis will be placed on initiatives that translate scientific advances into tangible practices for sustainable agriculture and resilient agroecosystems.
Orals: Mon, 4 May, 08:30–09:50 | Room -2.33
Biochar application is increasingly recognized as a promising strategy to enhance soil health and mitigate greenhouse gas (GHG) emissions. However, the mechanisms by which biochar simultaneously regulates fluxes of CO2, CH4, and N2O, modulates soil microbial communities, and reshapes the soil metabolite profiles remain elusive, especially under contrasting fertilizer regimes. To investigate these interactions, a two-season field experiment was conducted to assess the effects of rice husk biochar applied at four rates (0, 10, 20, and 30 t ha-1) in combination with mineral and organic fertilizers. Nine treatments were evaluated: negative control (CK), mineral fertilizer alone (MB0), mineral fertilizer with biochar (MB10, MB20, and MB30), organic fertilizer alone (OB0), and organic fertilizer with biochar (OB10, OB20, and OB30). High-throughput amplicon sequencing and untargeted soil metabolomics were employed to elucidate treatment effects on soil microbial community composition, metabolic pathways, and GHG emissions. Biochar-amended treatments substantially reduced global warming potential (GWP), with MB30 decreasing GWP by an average of 25.5% relative to MB0, and OB30 reducing GWP by 29.1% compared to OB0 averaged across both seasons. Biochar maintained overall microbial community stability, with no major shifts in alpha diversity or distinct taxonomic signatures, indicating minimal impact on community structure. Bacterial communities were dominated by Proteobacteria and Firmicutes in mineral fertilizer treatment (MB0), indicating a shift towards fast-growing copiotrophs, whereas biochar combined with organic fertilizer (OB10-OB30) enriched slow-growing Actinobacteria and Acidobacteria, enhancing microbial diversity and nutrient cycling. Fungal communities, primarily Ascomycota and Basidiomycota, showed increased diversity with biochar and organic fertilizer, promoting taxa like Mortierellomycota, Mucoromycota, and Glomeromycota involved in decomposition, nutrient cycling, and plant-fungal symbioses. Metabolomic analysis (MetaboAnalyst) using variable importance projection (VIP) scores and false discovery rate (FDR)-adjusted significance tests first identified discriminatory metabolites associated with increasing biochar rates under both fertilizer regimes. These metabolites were mainly enriched in the Shikimate and Phenylpropanoid pathways, polyketides, and alkaloids such as jasmonic acid, alternatain D, 4-O-demethylhypothemycin, and blennolide D, with further enhancement in isoflavonoid biosynthesis. Such shifts are consistent with biochar-mediated changes in soil properties and microbial composition, which are known to stimulate secondary metabolism, plant defense signaling, and microbially driven biochemical transformations. In contrast, treatments without biochar accumulated higher levels of fatty acids, amino acids, and peptides, reflecting altered microbial biomass turnover and organic matter decomposition. Integrating these insights with process-based modeling and life cycle assessments will provide robust quantification of biochar’s climate mitigation potential and support the development of effective guidelines for climate-smart agricultural management.
How to cite: Kesamreddy, L., Eagan, S., Ndungu, S. M., Ponnusamy, J., Mariappan , S., Ettiyagounder, P., and Pawera, L.: Integrative Assessment of Biochar Effects on Greenhouse Gas Emissions, Soil Microbiome, and Soil Metabolomic Profiles, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8513, https://doi.org/10.5194/egusphere-egu26-8513, 2026.
Nitrogen fertilization is a major driver of melon productivity in arid environments, yet excessive application leads to low nitrogen use efficiency and increased environmental risks, particularly nitrate leaching. This study investigated the effectiveness of chemical inhibitors in maintaining melon (Cucumis melo L.cv yellow canari) yield, quality, and nitrogen dynamics under reduced nitrogen fertilization in southern Tunisia during the 2025 growing season. The activities were carried out within the framework of the PRIMA project TELENITRO. The experiment compared a conventional nitrogen rate (control, N1) with two reduced nitrogen levels (15% and 30% reductions, N2 and N3), combined with two chemical inhibitors: 3,4-dimethylpyrazole phosphate (DMPP) and N-(n-butyl) thiophosphoric triamide (NBPT). Production parameters, yield components, fruit quality traits, and nitrogen forms in soil and leaves were evaluated. Results showed that a 15% reduction in nitrogen fertilization combined with chemical inhibitors effectively preserved fruit size and yield. Under N2, both DMPP and NBPT treatments exhibited fruit length, width, and seed cavity dimensions comparable to the control. Average total yield reached 37.5 and 40.0 t ha⁻¹ for DMPP and NBPT, respectively, showing no significant difference from the control yield (38.5 t ha⁻¹). These results highlight the strong capacity of chemical inhibitors to compensate for moderate nitrogen reductions. In contrast, a 30% nitrogen reduction (N3) led to a significant decrease in average fruit weight and total yield, although inhibitor-treated plots still outperformed what would typically be expected under reduced nitrogen conditions. Yields under N3 ranged from 26.0 to 28.5 t ha⁻¹, with NBPT showing slightly better performance than DMPP. Fruit quality attributes, including soluble solids content (SSC), dry matter content (DMC), and firmness, were not significantly affected by nitrogen reduction or inhibitor application, indicating that marketable quality was maintained across treatments. Soil nitrate and ammonium concentrations varied significantly over time and treatments. Reduced nitrogen treatments combined with inhibitors generally showed lower soil nitrate accumulation compared to the control, particularly at later sampling dates, suggesting improved nitrogen retention in the soil. Leaf nitrate concentrations were significantly lower in inhibitor treatments, especially under N3, while ammonium concentrations and increased C/N ratios indicated enhanced nitrogen assimilation efficiency. Overall, the results demonstrate that the combined use of chemical inhibitors, particularly NBPT, enables a reduction of nitrogen fertilizer inputs by up to 15% without compromising melon yield or quality under arid conditions. Overall, the findings support the use of chemical inhibitors—especially NBPT—as a viable nitrogen management strategy to reduce fertilizer inputs while sustaining melon productivity and minimizing environmental risks under arid conditions in southern Tunisia.
How to cite: Ayadi, I., Mahmoudi, N., Wassar, F., Toumi, I., Bali, M., Dakhli, R., ElBeji, R., Boukchina, R., Dhaouadi, L., and Garcia Sanchez, F.: Effectiveness of DMPP and NBPT in Sustaining Melon production under Nitrogen Restriction in Southern Tunisia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10830, https://doi.org/10.5194/egusphere-egu26-10830, 2026.
Coastal « green tides » - algal blooms caused by eutrophication - are a common occurrence throughout the world where rivers drain areas of intensive agriculture towards relatively closed bays. In Britanny (France) blooms of algea from the genus Ulva have been observed since the 1970’s, and despite four successive action plans to tackle their cause, still cause health, environmental and economic issues every summer.
Biochar is known to affect nitrogen dynamics in soils, reducing nitrate leaching and N2O emissions, in addition to increase the stable carbon pool of the soil. The greenhouse gases balance of a biochar system is strongly influenced by biomass source, and to a lower extent by transportation of the feedstock biomass and finished biochar [1]. Residual biomass that can be used as feedstock for biochar production is subjected to competing use, e.g. for animal bedding, incorporation to the soil, or anaerobic digestion. Local biochar systems based on residual biomass with little to no other uses (waste) are therefore likely to be more environmentally and economically sustainable.
In the SyBio project, we are investigating the biogeochemical consequences and technical and social feasibility of a local biochar system based on green algea biomass that is collected on the sandy shores of Britanny during algal blooms, as an alternative to direct application of algea to the soil or landfilling, the most common disposal options at present. In particular, we studied the effect of Ulva biochar on nutrient cycle and greenhouse gases emissions in the soil plant-system. We compared the effects of the biochar with that of direct application of algea, and also tested the combination of biochar and compost. We hypothesized that biochar application would reduce nitrate leaching and N2O emissions relative to the control situations and direct algea application, while plant growth and biomass yield would remain unaffected.
We carried out a climate chamber experiment, growing spring barley (Hordeum vulgare) in three soils with contrasting texture under a 10 years averaged climate typical of Britanny. We measured soil CO2 and N2O emissions, nitrogen forms in the soil solution and drainage water, and plant photosynthesis at regular intervals throughout the growing period. We will present the results of this experiment as well as insights from other aspects of the project.
[1] Lehmann, J., Cowie, A., Masiello, C.A. et al. Biochar in climate change mitigation. Nat. Geosci. 14, 883–892 (2021). https://doi-org.insu.bib.cnrs.fr/10.1038/s41561-021-00852-8
How to cite: Lebrun Thauront, J., Areia, J., and Abiven, S.: Proof of concept for a green algea biochar system in Britanny, France: an Ecotron experiment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19580, https://doi.org/10.5194/egusphere-egu26-19580, 2026.
Hydrochar produced through hydrothermal carbonization of organic residues serves as a char-organic input strategy aimed at closing nutrient loops, enhancing substrate function, and supporting sustainable plant production. This study investigates the effect of hydrochar feedstock and application rates on the physicochemical properties and early plant performance in recycled concrete aggregate (RCA), a significant component of construction and demolition waste. The research evaluates the potential of hydrochar to transform RCA into a viable substrate for sustainable urban landscaping and geo-environmental infrastructure development. Wood-derived and eggshell-derived hydrochars were compared, applied at rates of 5% and 10% by mass, to cultivate Brassica rapa var. chinensis for 21 days under controlled conditions. The assessment quantifies key material properties, including pH, electrical conductivity, organic matter, and total organic carbon. Additionally, plant production indicators such as germination rates, root and shoot development, biomass, and leaf area are measured, along with post-harvest carbon metrics to explore carbon sequestration potential. The experimental design emphasizes the response to application rates and the trade-offs associated with ionic strength and alkalinity. The goal is to identify hydrochar characteristics and amendment rates that promote growth-favorable chemistry, avoiding salinity or pH stress. This research seeks to establish practical guidelines for integrating hydrochar into low-cost, circular substrates for urban plant production and geo-environmental greening.
The authors would like to acknowledge the financial support provided by the State Key Laboratory of Climate Resilience for Coastal Cities (ITC-SKLCRCC26EG01) and the Research Grants Council of HKSAR (C5033-23G).
Keywords: hydrochar, plant production, recycled concrete aggregate, carbon sequestration
How to cite: Dela Cruz, T. L. M., Wang, Y., and Ng, C. W. W.: Hydrochar-Amended Recycled Concrete Aggregate for Plant Production and Carbon Retention, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15857, https://doi.org/10.5194/egusphere-egu26-15857, 2026.
Livestock manure, enriched with essential nutrients, represents a promising feedstock for insect farming. Insect protein offers a circular and high-quality alternative to conventional crop-based livestock feed, potentially reducing both environmental and resource pressures. In this study, we integrate global livestock models with trade, land-use, and cost-benefits analysis to quantify the environmental and economic implications of manure-to-insect conversion while ensuring the recycling of manure to croplands to maintain soil fertility across 166 countries. Our analysis show that scaling up this pathway could yield approximately 4.2 million tons (Mt) of insect protein N to substitute crop-based feed, and releasing up to 45 million hectares of cropland. This transition could mitigate N and GHG emissions by 6.0 Mt N and 1,266 Mt CO2-e during feed cultivation and manure storage. The residual manure, after insect processing can be returned to fields as a high-quality and stable organic fertilizer, offsetting 23 Mt N of synthetic fertilizer demand. With an estimated implementation cost of 25 billion USD, this strategy could deliver combined economic and environmental benefits of 225 billion USD. These results highlight manure-based insect farming as a scalable, cost-effective, and circular solution for reducing global agricultural pollution and enhancing food system resilience. This pathway demonstrates how reimagined nutrient cycles can mitigate planetary health challenges by integrating food security, climate mitigation, and sustainable resource use within a unified circular framework.
How to cite: Cheng, L., Zhang, X., Rosa, L., Ren, C., Zhang, S., Zhang, Z., Yang, Y., Wang, W., Gong, Y., Zhu, Y.-G., and Gu, B.: From manure to insects: circular transformation of livestock manure for nitrogen and greenhouse gas mitigation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4121, https://doi.org/10.5194/egusphere-egu26-4121, 2026.
Phytoremediation is an efficient and low-cost alternative to mitigate the impacts caused by heavy metals in the environment. The efficiency of phytoremediation of copper-contaminated soil can be enhanced by the addition of organic amendments, such as vermicompost. However, different vermicomposting time results in different chemical, physical, and biological properties of the vermicompost, which may consequently influence its efficiency as a phytoremediation amendment. The objective of this study was to evaluate the effect of cattle manure vermicomposting time on the efficiency of vermicompost in enhancing the phytoremediation of copper-contaminated soil. Black oat (Avena strigosa Schreb.) was cultivated in a greenhouse for 60 days in 5-kg pots containing an Acrisol with 889 g kg⁻¹ sand. The soil was collected from the surface layer of a vineyard with a copper (Cu) content of 104 mg kg⁻¹ (Mehlich-1) due to the long-term use of Bordeaux mixture (copper sulfate + calcium oxide) as a fungicide. Manure was obtained from feedlot cattle raised for meat production. The four treatments consisted of manure without vermicomposting and vermicomposts produced after 30, 60, or 120 days of vermicomposting. The experiment was conducted in a completely randomized design with four replicates. The amendment dose added to the soil was equivalent to 155 kg ha⁻¹ of P, with adjustments of N and K levels using urea and KCl. At plant flowering, Cu toxicity on the functioning of the photosynthetic apparatus was evaluated by determining the chlorophyll index, effective quantum yield of photosystem II (Y(II)), initial fluorescence (F₀), and electron transport rate (ETR) using a pulse-amplitude-modulated fluorometer. Subsequently, roots and shoots were collected to determine dry mass and Cu concentrations in plant tissues. Overall, the results show that shorter vermicomposting times led to lower Cu concentrations absorbed by plants, reduced phytotoxic effects on the photosynthetic apparatus, and greater biomass production. Plants grown in the manure treatment (without vermicomposting) accumulated 443 and 19 mg kg⁻¹ of Cu in roots and shoots, respectively, and produced 362 mg plant⁻¹ of root dry mass and 504 mg plant⁻¹ of shoot dry mass. In contrast, plants grown with vermicompost produced after 120 days accumulated 489 and 34 mg kg⁻¹ of Cu in roots and shoots, respectively. As a consequence, phytotoxicity was intensified and biomass production was lower in shoots (331 mg plant⁻¹; p = 0.002) and roots (224 mg plant⁻¹; p = 0.007). Longer vermicomposting time of cattle manure results in an amendment that increases Cu uptake by black oat, which reduces plant growth and decreases total Cu accumulation in the plant.
How to cite: Jacques, R., Ramos, R., Santana, N., Lima, R., Tabaldi, L., Brunetto, G., and Silveira, A.: Copper phytoremediation is influenced by the production time of vermicompost used as organic amendment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8186, https://doi.org/10.5194/egusphere-egu26-8186, 2026.
The use of organic and inorganic soil amendments is increasingly promoted to enhance soil fertility and carbon sequestration in perennial cropping systems, yet field-based evidence on their temporal dynamics remains limited. This study investigates the evolution of soil chemical properties in a pear orchard located in Ospital Monacale (Ferrara Plain, Northern Italy), focusing on the surface layer (0–20 cm) of a fine-textured, clay-loam soil. The experimental design consisted of a randomized block layout aimed at assessing whether the application of biochar and zeolite-rich tuff could enhance the already known beneficial effects of compost. To this end, four treatments were established: i) an untreated control, ii) compost alone, iii) compost combined with biochar, and iv) compost combined with zeolite. Soil samples were collected at different times: immediately after amendment application (T0) and two years after application (T1). Different soil parameters were investigated: total carbon and nitrogen, inorganic nitrogen forms (ammonium and nitrate), total dissolved phosphorus, pH and electrical conductivity.
Results show a clear temporal signal in the surface horizon. Compost and compost–biochar treatments promoted a sustained increase in total soil carbon relative to the control, with differences already evident at T1, suggesting progressive stabilization of organic carbon pools. In contrast, compost–zeolite mainly influenced nitrogen dynamics, with higher ammonium retention and reduced short-term variability compared to other treatments. Dissolved phosphorus concentrations were consistently higher in the treated soils compared to the untreaded one.
Overall, the integration of a multi-temporal framework reveals that, under humid and fine-textured soil conditions, amendment effects strengthen over time in the topsoil. These findings underline the importance of long-term monitoring to capture amendment-induced shifts in soil biogeochemical functioning in orchard systems.
How to cite: De Grandis, R., Ferretti, G., Alberghini, M., Ercoli, R., Basaglia, M., and Coltorti, M.: Short-term to mid-term effects of organic and inorganic soil amendments on carbon and nutrient dynamics in a clay-loam pear orchard soil (Ospital Monacale, Northern Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9825, https://doi.org/10.5194/egusphere-egu26-9825, 2026.
Nutrient enrichment, driven by agricultural intensification and urbanisation, is a major contributor to water quality deterioration globally. Excessive nitrogen (N) and phosphorus (P) inputs lead to eutrophication, hypoxic zones, and harmful algal blooms, while also representing economic losses for farmers and environmental challenges due to the reliance on inorganic fertilisers. External Organic Amendments (EOAs), such as compost and manure, offer a sustainable alternative by recycling nutrients, improving soil health, and reducing greenhouse gas emissions. However, the variability in nutrient release from EOAs, particularly N mineralisation, poses challenges for their effective use. Composted and biochar amendments have shown potential to stabilise nutrient release and mitigate environmental losses, but their biogeochemical dynamics remain poorly understood, especially under future climate scenarios involving intensified drying- rewetting (DRW) cycles. This study aims to address critical knowledge gaps by employing dual- labelled (13C-15N) composted and fresh poultry manure to quantify gross N and C mineralisation rates, assess microbial and biochemical mechanisms, and evaluate nutrient leaching potentials under constant moisture and DRW cycles. A combination of laboratory incubations and greenhouse soil column experiments will be conducted to compare the efficiency of composting and biochar amendments in improving fertiliser-use efficiency and reducing nutrient losses. Advanced isotopic tracing techniques will be used to disentangle amendment-derived nutrient dynamics from native soil pools, providing novel insights into the fate of dissolved organic matter and nutrient transport in agricultural soils. The findings will inform sustainable nutrient management practices and contribute to mitigating nutrient pollution under changing climatic conditions.
How to cite: Orepic, D.: Mind your manure: Impacts of biochar and dry-wet cycling on microbial processing of dual-labelled 13C-15N poultry manure compost , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18918, https://doi.org/10.5194/egusphere-egu26-18918, 2026.
Liquid-applied mulches (hydromulches) have been proposed as a biodegradable alternative to conventional plastic mulches, with the potential to improve the sustainability of agricultural and urban systems. Although their effectiveness in weed control and soil moisture conservation has been demonstrated, there is still limited knowledge about how hydromulch composition, particularly the origin of the lignocellulosic residues used, affects their degradation and soil biological activity in the medium and long term.
In this study, we assessed the effects of twelve hydromulch formulations prepared from different agricultural and agro-industrial residues of herbaceous and woody origin on soil biological quality. The experiment was conducted under controlled conditions using a 300-day microcosm incubation. Hydromulches were incorporated into agricultural soil, and key indicators of microbial activity and soil functioning were periodically measured, including soil respiration and several enzyme activities.
Overall, soil biological activity increased after hydromulch application, although clear differences were observed depending on the type of residue used. Some formulations caused strong and early stimulation of microbial respiration and enzyme activity, whereas others showed more moderate but longer-lasting effects. Similarly, enzymatic activities associated with different nutrient cycles responded differently depending on hydromulch composition, reflecting distinct degradation patterns and substrate availability.
These results suggest that hydromulches act not only as physical soil covers but also influence soil biological activity depending on their composition. Because microbial and enzymatic activities are closely linked to nutrient cycling, these effects may have important implications for soil fertility and soil health. Therefore, selecting specific residues for hydromulch formulation may be a useful strategy within circular bioeconomy approaches aimed at improving soil functioning.
Keywords: hydromulches, soil biological activity, agro-industrial residues, soil health
Acknowledgements: PID2020-113865RR-C43 (HMulchCircle)/AEI/10.13039 - 501100011033 (Spanish Ministry of Science and Innovation) / 2024-TRAN-36705 (University of Castilla-La Mancha)
How to cite: Moreno, M. M., Peco, J. D., Villena, J., Atance, C., Morales, P. A., Higueras, P. L., and Moreno, C.: Soil biological responses to bio-based hydromulches formulated from different agro-industrial residues under controlled laboratory conditions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18478, https://doi.org/10.5194/egusphere-egu26-18478, 2026.
Common practices for weed control in horticultural and fruit crops often rely on herbicides, petrochemical plastics and intensive tillage. However, the environmental impact of these techniques has encouraged researchers worldwide to explore more sustainable alternatives aligned with circular economy principles. These eco‑friendly approaches could also be applied to other production systems, such as seedbeds or nursery plants. Within this context, biopolymers and paper-based materials show promising performance, although their shorter lifespan makes them more suitable for annual herbaceous crops. Based on preliminary laboratory tests, we therefore established a field trial in a forest tree nursery in Central Spain, applying hydromulches of different compositions and characteristics to newly transplanted seedlings grown in open-field conditions.
The hydromulches were formulated using agricultural and agri‑food by‑products—wheat straw, camelina pellet, almond pruning wood, elm + walnut, and a mixture of elm, walnut and camelina. These materials were combined with a binder and recycled paper pulp, and applied in liquid form to the soil, where they subsequently solidified. In addition, two unmulched treatments were included as controls (manual weeding and no weeding) within a randomized complete block design with three replications.
In order to evaluate the possible effect of the different hydromulches on soil respiration, the CO₂ flux was measured using an EGM‑4 portable soil respiration system (non‑dispersive infrared gas analyzer) equipped with an SRC‑1 chamber (PP Systems). Measurements were taken between 12:00 and 14:00 (solar time) at the same point in each treatment. Throughout the trial, the degradation dynamics of the hydromulches (thickness, puncture resistance, soil cover, etc.) were also monitored, together with their influence on soil biological activity and mesofauna abundance. Clear differences were observed among treatments, with the camelina‑based hydromulch showing the fastest and most pronounced degradation. While this behavior could limit its effectiveness as a persistent weed control layer, it was associated with higher soil biological activity and supported a greater quantity of mesofauna.
Keywords: hydromulch, soil respiration, biological activity, mesofauna.
Acknowledgements: PID2020-113865RR-C43 (HMulchCircle)/AEI/10.13039 / 501100011033 (Spanish Ministry of Science and Innovation) / 2024-TRAN-36705 (University of Castilla-La Mancha).
How to cite: Atance, C., Villena, J., Peco, J. D., Morales-Rodriguez, P. A., Moreno, C., López-Perales, J. A., Higueras, P. L., and Moreno, M. M.: Behaviour and effects of organic hydromulches on soil biological aspects in nursery crops, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20917, https://doi.org/10.5194/egusphere-egu26-20917, 2026.
Reducing greenhouse gas (GHG) emissions from horticultural growing media (GM) is critical due to the high climate impact of peat extraction and use. Peatlands are major carbon reservoirs, and their excavation and use releases substantial amounts of CO₂, while also causing habitat loss and biodiversity decline. Bio-based alternatives, including extruded wood fibers, aged bark, various composts, degassed agricultural fibers from anaerobic digestion, and willow-derived biochar, offer potential for climate-friendly peat substitution.
This study quantified the cradle-to-use GHG emissions of individual bio-based GM components and six stakeholder-defined multi-component blends designed for strawberry, basil, Kalanchoe, and Buddleia, using life cycle assessment (LCA) with the ReCiPe 2016 Midpoint method. The functional unit was 1 m³ of substrate. The LCA included raw material production, pre-processing, transport, mixing, and substrate use. Economic allocation and system expansion were applied where production generated co-products.
Results indicate that individual bio-based components can reduce carbon footprints by more than 50% compared with pure sphagnum. Multi-component blends with partial to full peat substitution showed GHG reductions of approximately 45–90%, depending on the proportion and type of bio-based constituents. These findings highlight the substantial potential of bio-based growing media to lower greenhouse gas emissions while maintaining suitable physical, chemical, and biological properties for horticultural production.
How to cite: Hashemi, F., Smith, A. M., Foncillas, C. F., Værbak, S., and Knudsen, M. T.: Climate impacts of bio-based horticultural substrates: Life-cycle assessment of individual components and multi-crop blends, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14659, https://doi.org/10.5194/egusphere-egu26-14659, 2026.
Global population growth is increasing pressure on agricultural systems, which must boost food production while contending with climate change and the environmental impacts of unmanaged agricultural waste [1]. In this context, the valorisation of agricultural residues has gained importance as a strategy consistent with circular economy principles and supported by European initiatives focused on soil restoration [2]. Pyrolysis has emerged as a key technology for transforming biomass into value-added products such as syngas, biochar, and the liquid fraction bio-oil. However, the aqueous liquid co-product known as pyroligneous acid (PA, or wood vinegar) remains comparatively underexplored, despite its diverse bioactive properties and dose-dependent effects on soils and plants. A deeper understanding of its agronomic and environmental implications, particularly regarding soil processes and carbon dynamics, is crucial for advancing sustainable waste-valorisation strategies.
To address this gap, a short term field experiment was conducted to evaluate the safety of PA application under real conditions and its effects on soil carbon storage in the framework of the PIROVALOR project. PA was produced through pyrolysis of mixed wood-waste biomass at 500 °C in a continuous feed cylindrical reactor (Euthenia Energy, Lucena, Spain) and applied to a calcareous sandy loam (Calcic Cambisol) at a 50% (v/v) dose in ‘La Hampa’ farm (Seville, Spain). Soil samples were collected one and six months after application.
Preliminary results show that PA is free of pollutants and contains important macro and micronutrients, including Fe, Ca and N. Its application did not alter key agronomic or physicochemical properties, such as soil moisture, penetration resistance, bulk density, pH or electrical conductivity likely due to the strong buffering capacity of the calcareous soil. Short-term compositional changes were observed: total organic carbon and total nitrogen increased one month after application, returning to baseline levels by six months. Notably, PA enhanced the proportion of recalcitrant and intermediate soil organic matter fractions, suggesting the initiation of mechanisms that may contribute to longer-term carbon stabilization.
These findings indicate that PA can be applied safely under field conditions and may promote mechanisms of soil carbon stabilization, supporting its potential role within circular and sustainable biomass-valorisation strategies.
References:
[1] Kurniawati, A., Stankovics, P., Hilmi, Y.S., Toth, G., Smol, M., Toth, Z., 2023. Sustain. Chem. Climate Action, 3, 100033.
[2] Márquez-Moreno, J., Sánchez-Martín, Á., Pérez-Dalí, S. M., Rodríguez-López, C., Campos, P., Moreno-Robles, A., Souza-Alonso, P., López-Núñez, R., De la Rosa, J.M., 2025. Waste Management, 210, 115243.
Acknowledgement: The Ministry of Science, Innovation and Universities, the State Research Agency (MICIU/AEI/10.13039/501100011033) and the European Union (FEDER and Next Generation EU/PRTR) are thanked for funding the PIROVALOR (CPP2023-010757), RES2SOIL and AGRORES (PID2021 126349OB-C22 – PID2021 126349OB-C21) projects and the contract of P. Campos (PTA2023-02366-I). The technical support and collaboration of Euthenia Energy in the framework of the PIROVALOR project is also acknowledged.
How to cite: Pérez-Dalí, S. M., Sánchez-Martín, Á., Márquez-Moreno, J., Rodríguez-López, C., Campos, P., Rodríguez, A., Martínez, M., Merino, A., and de la Rosa, J. M.: Field application of pyroligneous acid enhances soil properties and supports Carbon stabilization pathways, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-431, https://doi.org/10.5194/egusphere-egu26-431, 2026.
Agricultural soils in the Mediterranean basin face a critical state of degradation, characterized by the depletion of organic matter and a high dependence on external inputs. Faced with this scenario, and the urgent need for practices to guarantee economic and environmental viability, the RESIOLIVA Operational Group and the RES2SOIL project propose an agroecological and circular management. The main objective is to safeguard the sustainability of certified olive groves and increase their adaptive capacity to climate stress.
A field trial was established in La Campana (Seville, Spain) to monitor 3,169 certified olive trees (cv. Sikitita-2 and Arbosana). A factorial experimental design was used to evaluate six treatment combinations across replicated plots, testing (i) the application of green compost + biochar produced from olive pomace and (ii) inoculation with beneficial Trichoderma spp. with plant growth–promoting activity, both individually and in combination. In addition, the influence of prior mycorrhization of the planting material was assessed.
The monitoring strategy combined soil physicochemical properties, elemental composition, water retention capacity, thermogravimetric analysis, and infrared spectroscopy with measurements of biological activity, as well as plant physiological assessments based on photosynthetic yield and chlorophyll content. Preliminary results showed that the organic-amended plots had statistically significant increases in soil organic carbon, mainly stable fraction, supporting its role as a carbon sink, while most of the physicochemical parameters remained stable. Besides, amended plots consistently maintained higher soil moisture levels at 0-20 cm depths. However, the trial was severely disrupted by extreme floodingin February 2025, accumulated rainfall exceeded 600 mm, causing prolonged waterlogging and anaerobic conditions and leading to higher-than-expected plant mortality, which reduced the statistical robustness of the first vegetative cycle, resulting in lower survival rates compared to controls. Notably, the rainfed-bread Sikitita proved highly susceptible to root asphyxia, whereas the irrigation-adapted Arbosana showed superior tolerance to high precipitation rates. Monitoring continues to assess amendment stability, C dynamics, and soil structural interactions, providing key information for designing rainfed scenarios.
ACKNOWLEDGEMENTS
The Resioliva Operational Group (GOPO-CO-23-0004) gratefully acknowledges funding from the European Agricultural Fund for Rural Development (FEADER) and the Regional Government of Andalusia through the Ministry of Agriculture, Fisheries, Water and Rural Development, in accordance with Article 18.4 of Law 38/2003 of November 17 (https://agriculture.ec.europa.eu/index_es).
This work was funded by the RES2SOIL project (PID2021-126349OB-C22) of the MCIN/AEI/10.13039/501100011033.
How to cite: Rodríguez-López, C., Márquez-Moreno, J., Pérez-Dalí, S. M., Sánchez-Martín, Á. M., Campos, P., Moreno-Ortega, J., Azpilicueta, A., González-Peñaloza, F., González-Pérez, J. A., and De la Rosa Arranz, J. M.: Revitalizing rainfed certified olive groves through the application of organic amendments and beneficial fungal consortia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7180, https://doi.org/10.5194/egusphere-egu26-7180, 2026.
The management of dredged riverine sediments represents a significant environmental challenge due to the massive volumes generated annually [1]. Reusing these sediments as agricultural amendments offers a promising opportunity to improve crop yields and plant quality [2]. In the Guadalquivir marshlands (Seville, Spain), soils also face severe physical constraints due to their clay-rich texture and low soil organic carbon content. In this context, targeted organic amendments, such as plant-based composts, are proposed to enhance nutrient availability and overall functionality in formulated Technosols.
Within this context, a six-month field trial was established in a fine-textured soil near the Guadalquivir River, characterized by compaction and poor drainage, under the framework of the SARECO Project, which formulated Technosols through the co-application of two riverine dredged sediments from the Guadalquivir River (supplied by the Port of Seville) and green compost, mixed with the native soil, as a strategy to restore soil health. Winter wheat was cultivated, and over the six-month period (until harvest) we monitored soil physical properties, organic matter composition and respiration rates, carbon dynamics, and crop productivity.
The results showed that the Technosols significantly improved soil physical properties, with lower soil bulk density and penetration resistance. These improvements were accompanied by sustained organic carbon enrichment throughout the trial. Soil respiration rates increased initially in the Technosols but declined over time. The combined application of sediments and compost produced a synergistic effect on yield, exceeding the control in grain weight and grains per head, while total biomass and protein content remained comparable to the control soil.
Overall, these findings confirm that combining riverine dredged sediments with organic amendments in fine-textured, carbon-poor soils is a sustainable strategy that increases soil organic carbon stocks while maintaining competitive crop yields. This approach provides a viable pathway for dredged-sediment valorization and the restoration of degraded agricultural soils.
REFERENCES
[1] Renella, G. Sustainability (2021), 13(4),1648.
[2] De la Rosa, J. M., Pérez-Dalí, S. M., Campos, P., Sánchez-Martín, Á., González-Pérez, J. A., & Miller, A. Z. Agronomy (2023), 13(4), 1097.
ACKNOWLEDGEMENTS: Authors gratefully acknowledge CSIC for funding the SARECO project (COCRE24015; CSIC COCREA 2024 – circular economy call). RES2SOIL project (PID2021-126349OB-C22) and P. Campos (PTA2023-023661-I) thank funding from MICIU/AEI (10.13039/501100011033) and the EU (FEDER, NextGenerationEU/PRTR) We thank Verónica Asensio and Rubén Leboreiro for their support, and Antonio Bejarano Moreno (Autoridad Portuaria de Sevilla) for providing access to the field plot area.
How to cite: Rodríguez-López, C., Campos, P., Pérez-Dalí, S. M., Márquez-Moreno, J., Sánchez-Martín, Á. M., González-Peñaloza, F., Bárcenas-Moreno, G., González-Pérez, J. A., and De La Rosa, J. M.: Engineered sediment-based technosols amended with compost: a pathway to recarbonize compacted soils and restore agricultural functionality, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17395, https://doi.org/10.5194/egusphere-egu26-17395, 2026.
