Monitoring the soil–plant system in forest ecosystems is crucial for preserving their ecological functions and services. This study assessed carbon and nitrogen stable isotopes and ecoenzymatic stoichiometry as suitable indicators for characterizing the soil–plant system as a functional unit of ecological processes. To this end, in June 2021 six plots (1 m2 each) were selected in two typical Mediterranean forest ecotypes: a coastal stone pine forest (Pinus pinea L., PF) and a meso-hygrophilous broadleaf forest (RV). Soil samples (0–15 and 15–30 cm depth) and litter samples (40 × 40 cm) were collected and characterized in terms of physical, chemical and biochemical properties. t-tests revealed significant differences between RV and PF, indicating distinct microbial nutrient acquisition strategies. The higher C:N ratio in PF suggested lower litter quality and greater recalcitrance to microbial decomposition. Consistently, RV showed a more pronounced 13C and 15N enrichment from litter to SOM down to a 30 cm depth, confirming faster organic matter decomposition and mineralization. Enzyme activity patterns supported these findings. The higher β-glucosidase and butyrate esterase activities in RV reflected its greater microbial potential to activate biogeochemical cycles. Both forests exhibited a higher microbial demand for C and P than for N to maintain ecological stoichiometric balance, with stronger C limitation at the surface and P limitation in the subsoil, particularly in RV soil. This integrated monitoring approach provides insights into nutrient cycling and ecosystem resilience and offers tools to evaluate ecosystem functionality under changing environmental conditions, supporting sustainable forest management.

Heavy metal contamination in soil and the resulting groundwater pollution are common at many brownfield sites. Soil washing, which dissolves contaminants into a washing solution to separate them from the soil matrix, has emerged as a promising remediation strategy. This study assessed the feasibility of applying soil washing to Pb-contaminated soil collected from an industrial area within the Trieste Port Authority (Italy) through a series of leaching tests. Batch tests were conducted using ethylenediaminetetraacetic acid (EDTA)-based extractants combined with various reducing agents to identify the most effective and environmentally sustainable washing solution. The results show that coupling EDTA with hydroxylamine hydrochloride or sodium dithionite significantly enhanced Pb solubilisation compared with EDTA alone, with dithionite emerging as the most suitable reducing agent due to its lower toxicity and reduced environmental impact. Sequential extraction tests revealed that up to 50% of total Pb could be removed after repeated washing cycles. Column leaching tests further confirmed the high efficiency of the EDTA-sodium dithionite system, achieving Pb removal rates of approximately 70% under continuous flow conditions. Overall, the results demonstrate that EDTA combined with low-dose sodium dithionite provides an effective and practical remediation strategy for heavily polluted industrial soils.

The EU Soil Monitoring and Resilience Directive (SMRD) establishes a harmonized framework for assessing soil health across Member States, focusing on chemical, physical, and biological descriptors. Currently, basal respiration is the only biological indicator of soil functionality suggested at the EU level, highlighting the need for complementary indicators that capture ecosystem processes and resilience under climate change and land management pressures.Microbial-based functional indicators represent a promising solution, as soil microorganisms rapidly respond to environmental stress and drive key biogeochemical processes. Drawing on a series of case studies, literature reviews, and findings from EU-funded projects carried out by our research group (LIFE and Next Generation EU), we emphasize the critical role of soil eco-enzymes as indicators of soil health conditions. Enzyme activities, such as β-glucosidase (BG), acid phosphatase (AP), and N-acetyl-β-D-glucosaminidase (NAG), could be suitable descriptors of functional microbial biodiversity. In view of this, soil enzyme activities could be introduced as new descriptors in the Annex I during the Directive’s scheduled revision in 2033.Microbial-released enzyme balance, under specific environmental conditions and spatial scales, could also contribute to evaluating and predicting the rate and efficiency of organic matter decomposition and immobilization, thus regulating the balance between stored C pools and CO₂ emissions. Integrating enzyme tests into SMRD monitoring protocols would provide robust descriptors of microbial processes influencing organic matter turnover. This approach strengthens the Directive’s capacity to evaluate soil health and resilience, offering a sensitive, easy-to-implement, and cost-effective functional indicators aligned with EU sustainability goals for 2050.

Nature-based solutions (NbS) are multidimensional, resource-efficient, and sustainable growth approaches to cope with current challenges, including biodiversity and carbon loss, pollution, climate change and land degradation. Amongst NbS, urban forestry is an important tool to enhance environmental resilience and sustainability, providing useful ecosystem services for human well-being. In this context, using suitable soil and plant indicators allows us to evaluate the efficiency of urban forestry in sustaining ecosystem functionality. Effective indicators should be sensitive to environmental changes and representative of ecological processes. Many studies focus on the selection of soil or plant indicators. The prior investigations considered soil–plant interaction and the related complex heterarchical and bidirectional effects involving plant strategy and soil biota. The choice and the use of indicators related to the soil–plant system could be an innovative strategy to better assess the following: (1) the ability of soil to support healthy plants and their ability to improve air quality; (2) the effect of urban forestry on ecological processes, in particular carbon and nutrient cycles. This review investigates the suitability of soil–plant system indicators related to nutrient cycles, e.g., ecological stoichiometry, enzyme activity and stoichiometry, and carbon and nitrogen stable isotopes, as valuable tools for planning and evaluating the effectiveness of urban forestry interventions.

The aim of this study was to investigate how biomass production and element distribution (nutrients and heavy metals) among plant organs (roots, stems, and leaves) were influenced by substrate physical and chemical properties, using acidophilic plants of Vaccinium corymbosum cultivars Bluecrop and Duke. A greenhouse pot experiment was conducted with highbush blueberry plants grown in an uncontaminated acidic peat-based control substrate (TS0) and two alkaline substrates enriched with remediated sediment (TS50 and TS100), characterized by high pH, Ca, and heavy metal concentrations. Both plant cultivars that were cultivated in sediment–based substrates exhibited a substantial reduction in plant growth, biomass production, and leaf chlorophyll levels. Limited translocation of microelements from belowground organs to leaves was observed across all plant samples. Cu, Fe, and Pb were predominantly accumulated in the roots of plants grown in TS-based substrates, with both cultivars acting as excluders for these metals by restricting their transport from roots to shoots. Mn and Zn were primarily retained in the stems and roots of highbush blueberry plants, with lower leaf accumulation. Notably, only Mn exhibited high translocation and bioaccumulation factor values (on average, 3.43 and 6.68, respectively), highlighting the species’ strong capacity for Mn accumulation. Specifically, control plants showed significantly higher Mn concentrations than those grown in TS-enriched substrates, likely due to the acidic conditions that enhance the bioavailability of this metal and the low Ca concentration in TS0, which is known to disrupt Mn accumulation in shoots. However, this accumulation did not reach toxic levels for the plants and did not negatively impact the physiological processes of control plants, which remained particularly efficient in the Duke cv, known for its Mn resistance. This study highlights the ability of highbush blueberry plants to selectively accumulate heavy metals when grown in polluted substrates under suitable conditions, making them a valuable model for understanding metal accumulation mechanisms in the Ericaceae family.

Soil-plant indicators are useful to select tree species suitable for the urban conditions and to maximize the benefits provided by green infrastructures (GE). To identify effective indicators for GE, soil-plant nutrient interaction and related physiological responses were assessed in evergreen (Cupressus sempervirens L.) and deciduous (Acer opalus Mill., Acer rubrum L., Tilia platyphyllos Scop., Ulmus ‘Plinio’) tree species, in a novel urban GE (Florence, Italy). Soil and leaf nutrient contents and the soil enzyme stoichiometry were applied as indicators of plant nutrient status and bioavailability. Gas exchange and stable isotopes of carbon (C) and nitrogen (N) were used as indicators of tree physiological status and resource-use strategies, respectively. The soil was suitable for tree growth, however, the enzyme activities estimated N limited condition. Trees differed in leaf nutrient composition and stoichiometry. Acer rubrum and A. opalus leaves had manganese concentration below and above the plant optimal range, respectively, leading to alteration in the nutrient uptake and on the leaf stoichiometry between C, N and phosphorus (C: N:P), with consequence for tree health status. Tilia platyphyllos and Ulmus ‘Plinio’ had the best photosynthetic performance, while photosynthesis in A. rubrum was severely impaired. Interspecific differences in N- and water-use strategies were observed. Tilia platyphyllos showed the highest water-use efficiency, leaf C: P and N: P compared to the other species. Tree nutritional and physiological traits gave insights into soil-plant nutrient interaction and may be proposed as useful indicators for choosing the most suitable species to improve GE management in urban environments.

The ornamental nursery industry is steadily growing in Europe, and a consequent increase in the demand for substrates related to container plant cultivations is expected in the coming years. Currently, substrates consist in part or entirely of peat, a non-renewable resource with concerns about its environmental impact due to extraction, transport, and use. Therefore, it is essential to focus on alternative materials, particularly waste by-products to be recycled as components of substrates to achieve more sustainable cultivations. In this study, substrates obtained by mixing co-composted dredged sediments (S) and green waste (GW) in different ratios (1:3; 1:1; 3:1) were tested for cultivation, and plant growth was compared with a control growing media (peat and pumice in a 1:1 ratio). The cultivation trial lasted for one year and was carried out on two potted ornamental evergreen shrubs (Photinia × fraseri and Viburnum tinus). The results showed that the plant growth parameters of both species, occurring in substrates with co-composted materials, were not significantly affected compared to the control, with the exception of below-ground biomass in V. tinus. Moreover, a Life Cycle Assessment (LCA) analysis was carried out to quantify the greenhouse gas emissions (GHG) deriving from the replacement of peat with the other proposed substrates. The functional unit was 10 L (Ø 24 cm) potted plants and the results were expressed in kg of CO2 equivalent (kg CO2eq). We demonstrated that the replacement of peat-based substrates with the alternative substrates was able to reduce the GHG emission by an average of 11.56 to 23.13%. Higher GHG emissions were related to the cultivation phase (0.9 kg CO2eq/plant), and while comparing substrates, we obtained an average percentage reduction of 28.1% to 59.6%. Thus, our results suggest that co-composted mixtures of dredged sediments with green waste could be used as sustainable techno-soils for pot nursery cultivation of ornamental species with reduced environmental impact.

In semiarid environments, vine cultivation is a land use with a high impact with regard to soil erosion, loss of organic matter and biodiversity, contamination, and compaction. In addition, the wine supply chain produces a considerable quantity of organic waste, which remains as residues in the ecosystem. Within this context, we developed a sustainable vine management system to improve the efficient use of fertilisers by applying a by-product derived from the composting of winery wastes and zeolite. We evaluated the effects of the zeolite-based compost on the chemical, physical, and biochemical soil properties of a productive vineyard. Four treatments were set up and monitored for about two years. These were as follows: (1) Commercial compost (COM); (2) Zeolite (Z); (3) 30% zeolite and 70% winery waste compost (30 ZEO); (4) 10% zeolite and 90% winery waste compost (10 ZEO). The results demonstrated that the ZEO treatments could be considered a win–win solution able to improve soil water content, nutrient retention, carbon sequestration, and biochemical activity while also recycling wastes. In particular, 10 ZEO seems to be the amendment that best combines an improvement in soil biochemical properties with gradual and constant nutrient availability, thus satisfying, without exceeding, soil and plant needs.

Co-composting efficiently reclaims dredged sediments (S) and green waste (GW), creating stable products for agricultural applications. However, the use of S-GW co-composts can be limited by legislative thresholds, especially for co-composts with a high S percentage. The evaluation of S-GW co-compost stability by biological assessment can allow for a better understanding of S and GW recycling, as well as the S-GW co-compost application. For this purpose, the microbial biomass, composition, respiration, and eco-enzyme stoichiometry (EST) were assessed, coupled with chemical analysis, in the co-composting of S and GW in different ratios. The Photinia x fraseri and Viburnum tinus L. growth was monitored in a plant trial, comparing the studied co-composts with a control substrate. The EST approach was applied as an indicator of the co-composting stability during the process and after the plant cultivation. The chemical and biological parameters confirmed the suitability of co-composting in the GW and S recovery and the EST approach highlighted a better stability for the 3S:1GW co-compost at the end of the process and after plant cultivation. Viburnum tinus showed a similar growth to the control, while Photinia x fraseri resulted in being more sensitive to the co-compost. The biological assessments were good indicators of the S-GW compost stability for their application in crop cultivation.

The production of wool is an economic burden and an issue for sheep breeders in many countries of the European Union because shorn greasy wool is defined as an animal byproduct (category 3) and must be sent to landfill as a special waste if not addressed in the textile supply chain. Nevertheless, wool is an important source of nitrogen, with high potential as agricultural renewable and sustainable organic fertilizer. To apply wool to soil, any contamination from harmful bacteria (e.g., Listeria monocytogenes and Salmonella spp.) should be excluded. In this study, we developed sheep wool pellets to test their suitability for use as an organic fertilizer. Wool was rich in N (12% of dry material) and was mixed to spruce sawdust at sawdust: wool ratios of at 2:1; 1:1 (v/v) to increase soil organic carbon. Despite the different mix of wool and sawdust, pellets were similar in size (diameter and length), and the content of the elements suited the requirements of fertilizers and did not present harmful bacteria after pelletization. Therefore, wool pellets may represent a feasible solution to provide sheep wool with an added value, introducing it in a circular economy process. However, further study is needed to test the effects of the produced fertilizing pellets in real cropping systems.

The high variability in composition and quality of green residues, especially those derived from the nursery sector, limits their recovery and recycling. Vermicomposting (VC) is a promising sustainable technology for recycling green residues from nurseries. This transforms them into nutrient-enriched resources thanks to its ability to degrade recalcitrant materials. We tested VC using a circular economy approach to recover various green lignocellulosic residues, i.e., dry chopped green waste (GW), sawdust (SW) and woodchips (WC), from local nurseries (Pistoia, Italy). Different mixture proportions were used (100

The paper aims to valorise winery waste into a co-composting process with natural clinoptilolite zeolite to improve the agronomic value of compost and simultaneously achieve sustainable recycling of organic wastes. The innovation of this study lies in the role of natural zeolite in winery waste valorisation and recycling. The winery waste materials after the harvest were composted in the presence of natural clinoptilolite zeolite at the following rates: (1) zeolite 0

This study aimed to assess the feasibility of the ecoenzymatic stoichiometry and isotope signature approaches as indicators of urban soil functionality, related to carbon and nutrient cycles. In Pisa and Livorno (Italy), study sites with three degrees of urbanization (natural, peri-urban and central urban sites) were selected, where holm oak (Quercus ilex L.) was the most common evergreen species. The urban and peri-urban sites differed in terms of NO2 emissions. At each site, topsoil and plant litter were sampled, pH, EC, TOC, and TN were measured in soil and δ13C and δ15N in soil and plant litter. The β-glucosidase, acid phosphatase and N-acetyl-β-D-glucosaminidase enzyme activities were also determined in soil and the ratios were calculated. The δ15N in plant litter increased from peri-urban to urban sites, along with the NO2 emissions, emerging as a sensitive indicator of atmospheric N deposition. The δ15N and δ13C increased in soil, indicating more rapid N cycles and organic matter degradation in peri-urban and urban areas than in natural areas. The ecoenzymatic stoichiometry revealed C and P microbial limitations for all the sites studied. However, the microbial needs of C and P increased and decreased, respectively, along the urbanization gradient. Isotope abundance and microbial nutrient limitations were found to correlate with soil properties. Specifically, soil δ15N was closely correlated with microbial C limitations. The isotope signature and enzymatic stoichiometry used as indicators revealed that the soil characteristics affected the soil carbon and nutrient cycles as well as microbial energy and nutrient needs.

Co-composting is suitable technology for recycling dredged sediments (S) and green wastes (GW), whose recovery are limited by their contamination and variability in composition, respectively. Some limitations in the process have been previously detected (e.g., limited thermophilic phase and low organic carbon content in the final product), thus restricting the use of co-compost for agricultural purposes. To optimize the co-composting and extend the application of the co-compost, the GW content in the piles (3S:1GW, 1S:1GW and 1S:3GW) and the pile volumes was increased. At the end of the process, the co-compost properties were compared to current legislation. The co-composting’s impact on the environment and its possible replacement of peat were also assessed by LCA. Maturity and stability were reached in all piles: enzyme activities (< 2214–39 µmol g−1 h−1), electrical conductivity, total organic carbon, phytotoxicity (GI > 100

Recently published research findings from EU projects have provided scientific evidence of the potential reuse of remediated dredged sediments in agriculture. Given that bottom sediments might be polluted by organic and inorganic contaminants, remediated sediments could better be recycled as an ingredient of soilless growing media for no-food crops, such as flowers and ornamental plants. Hence, the use of peat, which has a high environmental impact, could be reduced. In the present study, phytoremediated and landfarmed sediment was reused as plant substrates for the cultivation of calla lily for cut flower production. Three different substrate mixtures were tested, combining different proportions of the remediated sediment (0, 25 and 50%) with a standard peat-based substrate. Calla rhizomes were planted in 30 L pots containing the chosen mixtures. The experiment set-up was performed under greenhouse conditions, and three different water regimes were applied. Before and at the end of the plant cycle, the substrates were characterized by a number of physical, chemical and biochemical parameters. Calla vegetative growth and productivity in terms of leaf stem and leaf blade length, number of flowers, flower length, color of flower spathe and flower senescence were monitored during the plant life cycle. Physiological parameters such as fluorescence of chlorophyll, nutrients and heavy metal concentrations in leaves were analyzed as well. Significant differences were observed among the tested growing media and water regimes for all considered growth and productive parameters. Plants grown on a mixture containing 50% remediated sediment under high water supply exhibited more significant plant development and higher cut flower production and vase life quality. These results demonstrated that the treated sediment might be used as a partial substitute for peat for the production of calla lily cut flowers.

Sediments remediated with a nature-based solution approach (NBS-sediments) can represent a suitable and affordable alternative to peat as a constituent of growing media for ornamental plant production based on the combination of advanced production efficiency and rational green use of resources, including peat and water. In a greenhouse experiment, the effect of different growing media containing NBS-remediated sediments on two-year-old container grown cherry laurel (Prunus laurocerasus cv. ‘Novìta’) under standard and induced restrictive irrigation was evaluated. Six ternary mixes with different proportion (45:30:25 and 30:20:50 v/v) of peat:pumice:sediment (PE:TS25, PE:TS50), coconut fiber:pumice:sediment (CF:TS25, CF:TS50) and wood fiber:pumice:sediment (WF:TS25, WF:TS50) were tested in comparison to the standard peat:pumice blend (60:40 v/v), commonly used for pot ornamental crops ad used as control (PE, control). Pots were drip irrigated with 200 and 250 cc daily water volume (DWV). Cherry laurels grown in the control showed the lowest sign of stress, maintaining the highest net CO2 assimilation and transpiration rates, however stomatal conductance was reduced compared to PE:TS mixes. On the other hand, photosynthetic performance was strongly depressed by WF:TS25 and WF:TS50 under reduced DWV compared to the control, due to the combined effect of physical properties of the used matrices and reduced water availability. Nevertheless, final biomass production of plants grown on sediment-based growing media was similar to that of control, indicating that photosynthetic performance of plants fully recovered during the cultivation period. Differences in final plant development were negligible when compared to quality standards of marketing categories. Thus, appropriately blended NBS-sediment-based growing media can be used on a larger scale to produce rustic outdoor ornamentals.

Purpose There is a high quantity of dredged sediments produced every year. Both their landfill disposal and high pollutant concentrations lead to concerns regarding sustainability. The use of dredged sediment in growing media for horticulture is an opportunity to improve its recycling and to reduce the use of non-renewable materials, such as peat. For this purpose, marine sediments, phytoremediated in the framework of the AGRIPORT project (ECO/08/239065), were selected as a substrate component for pomegranate cultivation. Material and methods Phytoremediated sediments underwent 3-months landfarming, to improve their chemical and physical properties and to reduce hydrocarbon concentration. Afterwards, remediated sediment (RS) was mixed with peat (P) in a ratio of 50%. The tested substrates were (v:v) 100% RS (S100), 50% RS and 50% P (S50) and 100% P (S0) as control. Punica granatum L. var. “Mollar de Elche” and “Purple Queen” were selected as target plants. The sediment during the landfarming and the growing media during the plant growth were monitored through physical, chemical, and biological analysis. In addition, the plant performance was evaluated by dry biomass determination. Results and discussion Landfarming decreased electrical conductivity and bulk density as well as increased soluble C and N, reducing hydrocarbon concentration in RS, due to the increase in microbial metabolism. The RS respected the Italian legislation limits for growing media, except for bulk density and organic carbon. The RS + P substrate reached the required legal limits. During plant growth, substrates showed low mineralization, and the increased release of nutrients suggested beneficial changes in the rhizosphere. Higher availability of nutrients was detected in P and a decrease of metal concentrations occurred, as result of the plant uptake. The differences in the substrate properties influenced the pomegranate development with a variety-specific effect. “Purple Queen” increased the dry biomass, while no differences were observed for “Mollar de Elche.” Conclusion The use of sediment-based substrates (50% and 100%) for pomegranate cultivation, specifically for the “Mollar de Elche” variety, contributes to reducing peat application in horticulture.

The main results of the experience of CNR-IRET Pisa regarding sediment recovery and recycling are reported. In the AGRIPORT project, saline and brackish sediments were mixed with agronomic soil and underwent phytoremediation. After two years, heavy metals and hydrocarbons decreased, and the improvement of chemical and biological properties created a “functional soil” for further applications. Both phytoremediated sediments were refined through landfarming in the CLEANSED and HORTISED projects and applied for civil and agricultural uses. The landfarming process further reduced the organic contaminants in both sediments. Then, in CLEANSED, nursery plants performed similarly in brackish sediment-based substrates as in alluvial soil (control) (33% and 50%). In HORTISED, horticultural plants, grown on substrates with peat and remediated saline sediments (50%), had a yield, number, weight, and fruit quality comparable with those grown on peat. In the “Fondazione Cassa di Risparmio di Pistoia e Pescia” project, the decontaminated saline sediments were successfully co-composted with Posidonia oceanica and reused as nursery growth substrate. Another two European LIFE projects are still in progress. The SUBSED project aims to confirm the suitability of saline-remediated sediments after landfarming as an alternative substrate to peat and coconut fiber for fruit, flowering, and non-food crops. The AGRISED project aims to recover brackish sediments through a co-composting process with green waste to produce an innovative substrate for the cultivation of ornamental plants. The projects confer environmental, economic, and social values to sediments, through their eco-sustainable recovery and use in different sectors.

Because of the high costs and environmental impacts of peat and chemical fertilizers, the search for sustainable alternatives is increasing. Posidonia-based compost (C) has been widely tested as a growing media, while the combination with decontaminated dredged sediments (S) has only recently been studied. Moreover, little information is available on the relationship between plants and growing media. In this work, the suitability of growing media (CS) composed of 100% C, 70% C + 30% S and 30% C + 70% S were investigated compared to peat, for ornamental plants (Elaeagnus macrophylla, Photinia × fraseri and Viburnum tinus). Plant growth, physiological, nutritional and antioxidant responses were also investigated. The CS were compliant with current legislation on growing media. The Cu (+60%; +70%), Mg (+11%; +23%) and Ca (+66%; +72%) concentrations were higher in CS with 30% and 70% of S, respectively, than peat. The plants growing in CS had lower antioxidant activities than those on peat, suggesting a better plant tolerance to abiotic stress. In conclusion, the use of CS growing media, especially those with 30% and 70% of S, can be a valuable strategy to replace peat and reduce the application of fertilizers.

Purpose Intensive horticulture relies on non-renewable materials and creates high environmental concern due to peat overexploitation and long-distance transportation. Emerging research is therefore looking for alternative growing media. The aim of this study was to demonstrate the possibility of converting waste (dredged sediment) into a product (commercial substrate) through sustainable techniques. Methods Sediments from the Leghorn port (Italy) were subjected to phytoremediation and landfarming before use for cultivation. Blends of treated sediment (0, 25, 50%) with standard substrates based on peat, pumice, coconut fibre, and wood fibre were used for the propagation of cherry laurel (Prunus laurocerasus) using rooted cuttings in a greenhouse and with different water regimes. Growing media were analysed just after mixing their constituents, before plant cultivation, and cherry laurel vegetative growth and physiological parameters were studied. Results The phytoremediated sediment was successfully used as growth medium constituent in all tested media other than peat and coconut fibre in proportions varying between 25 and 50%, whereas in combination with wood fibre, it reduced cherry laurel growth and aboveground biomass. Leaf chlorophyll content and lipid peroxidation did not differ regardless of substrate mixture and water regime. Discussion All sediment-based media showed physicochemical parameters and heavy metal content in line with Italian regulations. Although sediment-based substrates were rich in zinc, this element was found at very low concentrations in plants. Our results highlight that the treated sediment can be used as a partial substitute for standard raw materials, especially peat and coconut fibre, in container production of cherry laurel.