Volcanic tuffs rich in chabazite zeolites have been extensively examined for their potential to enhance soil properties and increase fertilizer efficiency, both in their natural state and when enriched with nitrogen (N). However, there is a scarcity of data regarding their utilization in acidic sandy soil, particularly when used alongside organic fertilizers. This paper presents the findings of a 50-day laboratory incubation study that investigated the dynamics of N pools in an acidic sandy-loam agricultural soil treated with various N sources. These sources included urea, N-enriched chabazite zeolite tuff, and pelleted composted manure applied at a rate of 170 kg N/ha. Additionally, the N sources were tested in combination with chabazite zeolite tuff mixed into the soil to assess its role as a soil conditioner. The results revealed distinct behaviours among the tested N sources, primarily impacting soil pH and N dynamics. Soil fertilized with manure exhibited slow N mineralization, whereas N-enriched zeolite displayed a more balanced behaviour concerning net NO₃⁻-N production and NH₄⁺-N consumption. Both N-enriched zeolite and urea temporarily altered the soil pH, resembling a “liming” effect, while pelleted manure facilitated a prolonged shift towards neutral pH values. Considering the water adsorption capacity of zeolite minerals, caution is advised when adjusting water content and employing combustion methods to measure soil organic matter in zeolite-treated soil to avoid potential inaccuracies. In summary, N-enriched chabazite zeolite tuff emerged as a valuable N source in acidic sandy-loam soil, offering a promising alternative to synthetic fertilizers and showcasing a sustainable means of N recycling.

Implementing efficient strategies for the circular recovery and reuse of nutrients from wastewaters is mandatory to meet the Green Deal objectives and Sustainable Development Goals. In this context we investigated the use of zeolitic tuff (containing chabazite and phillipsite) in the selective recovery and reuse of N from various anaerobic liquid digestates in view of their implementation in farm-scale treatment plants. We tested the method on three livestock digestates and two municipal organic solid waste digestates. Adsorption isotherms and kinetics were assessed on each digestate, and a large set of parameters, including (i) contact time, (ii) initial NH₄⁺ concentration, (iii) presence of competing ions, (iv) total solids content, and (vi) separation methods (microfiltration and clarification), were considered in the experimental design. Our results showed that the adsorption mechanism can be explained by the Freundlich model (R² up to 0.97), indicating a multilayer and heterogeneous adsorption, while the kinetic of adsorption can be explained by the pseudo-second-order model, indicating chemical adsorption and ion exchange. The efficiency in the removal of NH₄⁺ was indirectly related to the K⁺ and total solids content of the digestate. Maximum NH₄⁺ removal exceeded 90% in MSW-derived digestates and 80% within 60 min in livestock-derived digestates at a 5% solid/liquid ratio. Thermodynamic parameters confirmed favorable and spontaneous adsorption (ΔG up to −7 kJ⋅mol⁻¹). Farm-scale projections estimate a nitrogen recovery potential of 1.2 to 16 kg N⋅day⁻¹, depending on digestate type and process conditions. These findings support the application of natural zeolitic tuffs as a low-cost, chemical-free solution for ammonium recovery, contributing to sustainable agriculture and circular economy objectives.

This study investigates potassium-L zeolite (K-L) as an adsorbent for the removal of thallium (Tl⁺) from aqueous solutions, focusing on the relationship between cation exchange and framework structural response. X-ray powder diffraction (XRPD), thermal analysis, and Rietveld refinements were employed to monitor structural modifications upon Tl⁺ uptake, combined with batch adsorption experiments to evaluate the removal performance. At low Tl⁺ uptake, only minor structural perturbations occur, mainly involving slight shifts in extra-framework cation positions and limited rearrangement of channel water molecules. At higher Tl⁺ concentrations, a measurable anisotropic expansion of the zeolite framework is observed, consistent with partial substitution of K⁺ by Tl⁺ and progressive modification of the hydration environment within the pores. Moreover, the crystallographic distribution of Tl⁺ differs from that of the original K⁺ cations, suggesting a specific site preference during the uptake process. Batch experiments reveal rapid uptake kinetics, with equilibrium reached within minutes, and high removal efficiency up to 99.5%. The adsorption behaviour is well described by the Langmuir model, with a maximum adsorption capacity of 631 mg g⁻¹. These findings highlight the coupling between ion exchange and structural flexibility in K-L zeolite and support its potential application for efficient thallium removal from contaminated water.

Copper (Cu) is one of the seven essential micronutrients for plants, but its intensive use as a pesticide in agriculture, especially in organic and integrated production systems, has led to its progressive accumulation in European soils. This phenomenon poses a serious threat to soil biodiversity, water quality, and human health. Despite EU regulations limiting copper inputs to a maximum of 28 kg/ha over seven years (an average of 4 kg/ha/year), a significant amount of copper-based pesticides is still widely used, as they remain essential for controlling numerous fungal and bacterial diseases. However, their accumulation in soils and sediments has become an unsustainable environmental issue, particularly in Italy, Greece, France, and Spain, where agricultural land contamination is particularly high. The LIFE MICROFIGHTER project proposes an innovative solution to reduce or replace copper-based pesticides by demonstrating the efficacy of a new Zeo-Biopesticide, applied as a foliar treatment, composed of natural Italian zeolites (potassium chabazite) and a specific biocontrol microorganism (Pseudomonas sp. DLS65). The goal is to control major pathogens of grapevine, tomato, and olive (including downy mildew, bacterial speck, bacterial spot, olive knot, and peacock spot), exploiting Zeo-Biopesticide and hence reducing or avoiding the use of copper in organic and integrated agricultural systems. The efficacy of the method will be demonstrated with field trials (2-3 years duration) in Italy, Croatia, and Spain (a total of 9 fields).The specific objectives of the project includes: i) reducing copper inputs in agricultural soils from an average of 4 kg/ha/year to 2 kg/ha/year without compromising crop yield and quality, with the potential for complete copper replacement; ii) demonstrating a reduction in total soil copper concentration while promoting increased soil biodiversity; iii) raising awareness among farmers, policymakers, and other stakeholders about the environmental and health risks associated with copper-based pesticides, and promoting the adoption of the Zeo-Biopesticide as an effective and sustainable alternative; iv) conducting environmental monitoring campaigns, life cycle analysis (LCA), and developing a business plan to assess the economic and environmental sustainability of the new technology.To evaluate the effect of the zeo-biopesticide on copper reduction, copper concentrations in soils, both bioavailable and total, are determined in the first and third years of sampling through ICP-MS analysis. Additionally, other soil physico-chemical parameters, such as organic matter content, pH, electrical conductivity, and cation exchange capacity, will be measured to assess their correlation with copper concentrations. For better data visualization, distribution maps of total and bioavailable copper concentrations will be created for the different experimental fields. Currently, after one year of the project, the baseline has been established, and the corresponding distribution maps have been prepared. These data will be compared with those obtained after the second sampling to evaluate the actual reduction in copper and, consequently, the effectiveness of the zeo-biopesticide.

Volcanic tuffs containing high percentage of zeolites have been extensively studied, both in their natural state or enriched with nitrogen, as a means of enhancing soil properties and fertilizer efficiency. Limited data however exist on their application in acidic sandy soils and in conjunction with organic fertilizers.This work consists of a 50-day laboratory incubation study wherein the nitrogen dynamics in an acidic sandy-loam agricultural soil fertilized with various nitrogen sources were investigated. These sources included urea, nitrogen-enriched chabazite zeolite tuff, and pelleted composted manure. Additionally, the nitrogen sources were tested in combination with the addition of chabazite zeolite tuff in its natural state to act as a soil improver.The results revealed distinct behaviors among the various nitrogen sources, particularly affecting soil pH and nitrogen dynamics. Mineralization was very slow in manure-fertilized soil, whereas nitrogen-enriched zeolite exhibited a more balanced behavior in terms of net nitrate production and ammonium consumption. Nitrogen-enriched zeolite and urea demonstrated a temporary "liming" effect, while pelleted manure promoted a prolonged shift of soil pH toward neutral values.In conclusion, nitrogen-charged chabazite zeolite tuff proved to be a valuable nitrogen source in acidic sandy-loam soil, serving as a viable alternative to synthetic fertilizers and an effective means of nitrogen recycling.

The transition towards circular nutrient management requires fertilizers that enhance nitrogen (N) use efficiency while minimizing environmental losses. Struvite, a recovered magnesium ammonium phosphate, is increasingly proposed as an alternative to conventional mineral fertilizers such as monoammonium phosphate (MAP). However, the extent to which fertilizer chemistry interacts with soil properties to regulate microbial functioning and N cycling processes remains insufficiently understood.In this study, we investigated short-term N transformations, microbial activity, and greenhouse gas emissions in two agricultural soils differing in pH (acidic and alkaline) following fertilization with struvite and MAP. Soils were incubated under controlled conditions, and temporal changes in mineral N forms, soil chemical properties, and CO₂ and N₂O emissions were monitored. Microbial respiration and growth were quantified to assess microbial carbon use efficiency (CUE) and biomass turnover. To resolve underlying process rates beyond net fluxes, stable isotope techniques were applied to quantify gross ammonium and nitrate production and consumption, allowing the calculation of microbial nitrogen use efficiency (M-NUE).Fertilizer effects were strongly regulated by soil pH. In acidic soil, struvite promoted a more gradual and microbially efficient N turnover compared to MAP, characterized by distinct ammonium and nitrate transformation pathways and higher M-NUE. In alkaline soil, N cycling was dominated by rapid nitrification, which reduced functional differences between fertilizer types. Across both soils, fertilizer-specific shifts in microbial growth, CUE, and biomass turnover revealed changes in microbial resource allocation and N processing pathways.By integrating gas flux measurements, microbial efficiency indicators, and stable isotope–derived gross N transformation rates, this study highlights how soil chemical context governs the biogeochemical performance of recovered fertilizers. Our findings emphasize the need to account for soil pH and microbial functioning when optimizing the use of struvite and other circular fertilizers in sustainable agricultural systems.