Chemistry Center - Vila Real

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Soil amendment with Zeolites and Biochar influenced soil properties, photosynthetic performance and olive fruit and oil composition

Publication . Martins, Sandra; Silva, Ermelinda; Brito, Cátia; Martins-Gomes, Carlos; Gonçalves, Alexandre; Arrobas, Margarida; Rodrigues, M.A.; Nunes, Fernando M.; Correia, Carlos M.

Olive orchards represent a key agricultural system in the Mediterranean basin. Soil degradation processes associated to unsustainable agronomic practices and climate change could severely impact the sustainability of Mediterranean rainfed olive orchards. In this context, soil amendments are important tools that can be used to enhance soil fertility for sustained environmental quality and plant performance. For two years, we evaluated, under rainfed conditions, the effects of a fertilizer compound (FC) and its combination with zeolites (ZL) and biochar (BC) amendments on soil moisture, photosynthetic activity, yield, fruit and oil composition and quality indices. Although no significant effects were observed on crop yield, the application of ZL and BC improved plant photosynthetic performance due to lower stomatal limitations. The effects on soil quality were more evident in ZL amendment, due to the reduction of acidity, and enhanced moisture, cation exchange capacity, microbial biomass carbon and enzymatic activity. Results relative to olive composition show that the polyphenolic content was strongly influenced by treatments. ZL improved fruit fatty acid composition and oil quality, while BC enhanced the concentrations of polyphenols with high nutritional value (3,4-dihydroxyphenylglycol, oleuropein and rutin). In contrast, olive oil from FC fruits showed the poorest quality. The applied soil amendments appear to be a promising sustainable strategy to implement in olive rainfed orchards, and can be an interesting complement to mineral fertilization, in order to promote soil quality, increase physiological performance and olive oil quality.

2022Conference object

Open access

Comparative antioxidant and antimicrobial properties of Lentinula edodes Donko and Koshin varieties against priority multidrug-resistant pathogens

Publication . Garcia, Juliana; Afonso, Ana Cristina; Fernandes, Conceição; Nunes, Fernando M.; Marques, Guilhermina; Saavedra, Maria José

The problematic increase in multidrug-resistant bacteria translates into the urgent need to discover novel and effective antimicrobial substances. Herein, mushrooms could be a promising alternative of natural source of new antimicrobials. The present work aimed to compare the phytochemical composition and antimicrobial activity of methanol and aqueous crude extracts of Lentinula edodes var. Koshin and Donko. Disk diffusion method was used to screen the antimicrobial activity and to assess the synergistic effect of the mushroom extracts. Microdilution method was used to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Phytochemical characterization of mushrooms extracts was achieved by analysis of total phenols, ortho-diphenols content and its antioxidant activity. The results noticed a positive relation between phenolic compounds content, antioxidant activity, and antimicrobial capacity of the mushroom's extracts. The L. edodes var. Koshin aqueous extracts, which contained the highest amount of total phenolic compounds, exhibited the highest scavenging capacity of ABTS which, in turns, exhibited the highest antimicrobial efficacy in inhibiting the growth of methicillin-resistant Staphylococcus aureus. Moreover, the combination between mushrooms extracts and commercial antibiotics showed favorable synergistic effects against tested bacteria. These results suggest that L. edodes var. Koshin may represent an important and valuable therapeutic source of compounds to be used against multidrug-resistant bacteria.

2021Journal article

Open access

Improving the sustainability of rainfed olive orchards by using zeolites and early-maturing annual legumes cover crop

Publication . Martins, Sandra; Silva, Ermelinda; Brito, Cátia; Pinto, Luís; Martins-Gomes, Carlos; Gonçalves, Alexandre; Arrobas, Margarida; Rodrigues, M.A.; Correia, Carlos M.

Olive cultivation is considered as one of the most significant agricultural activities in Mediterranean region, from a financial, social and ecological point of view. Under climate change threats, there is a growing need to adapt the conventional agronomic practices used in rainfed olive orchards by sustainable practices, in order to preserve soil health, while ensure olive tree performance and olive oil quality. During three years, the effects of leguminous cover crops (LC) and its combination with zeolites (ZL) were evaluated on soil properties, olive tree physiological performance, yield, composition and quality of olive fruits and oil, and compared with soil tillage (T). Results show that both LC and ZL strategies were able to improve photosynthetic performance and crop yield, relatively to T. However, ZL strategy was clearly more efficient in improving soil quality, through decreasing acidity, improving soil N, P and B availability, CEC and soil microbiology. Considering the effects of these practices on olive fruit and oil composition, ZL increased the oleic/linoleic ratio on fruits, and the levels of 3,4-dihydroxyphenylglycol, tyrosol, verbascoside and caffeic acid on olive oil. In short, both sustainable soil management strategies appear to be promising practices to implement in olive orchards under rainfed conditions, but the innovative strategy of combining zeolites with legumes cover crops confer advantages from a nutritional and technological point of view, while preserving soil quality. Nevertheless, studies subjected to long-term use of these practices should be experienced to ensure the sustainability of crop yield and olive oil quality

2022Conference object

Open access

Response surface method-driven design of experiments for the synthesis of fly ash-based geopolymers in the gallic acid optimized removal from wastewater

Publication . Silva, Ana P. F.; Natal, Ana Paula Silva; Baldo, Arthur Pietrobon; Silva, Adriano S.; Díaz de Tuesta, Jose Luis; Marin, Pricila; Peres, José A.; Gomes, Helder

The growing need for sustainable wastewater treatment solutions has led to exploring alternative materials to explore large-scale and reliable technologies. This study focuses on optimizing the synthesis of geopolymers based on fly ash using a Box-Behnken experimental design to enhance their adsorption efficiency for phenolic compounds, as gallic acid model pollutant which are widely found in wastewater leaching from landfills. Fifteen geopolymer samples were synthesized, characterized, and tested for adsorption performance. Various techniques were employed, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy. The optimization process highlighted the significance of the Si/Al mass ratio, NaOH molar concentration, and Na₂SiO₃/NaOH as variables in the geopolymers production. Geopolymer samples demonstrated significant adsorption capacities, with GP_2.0_10_2.5 achieving a maximum adsorption capacity of 75.8 mg g-1. Kinetic studies indicated that the pseudo-first-order model best described the adsorption process. At the same time, equilibrium data fitted well with both Langmuir and Freundlich isotherms, with GP_2.0_10_2.5 showing the best fit for the Langmuir model. These findings reveal the potential of geopolymers derived from fly ash as cost-effective adsorbents in wastewater treatment, promoting the reuse of industrial waste within the framework of a Circular Economy.

2025Journal article

Open access

Differential responses of photosynthesis, yield and soil properties 4 years after a single application of zeolites and biochar in a rainfed olive orchard

Publication . Martins, Sandra; Brito, Cátia; Gonçalves, Alexandre; Moutinho-Pereira, José; Pereira, Ermelinda; Arrobas, Margarida; Rodrigues, M.A.; Nunes, Fernando; Correia, Carlos M.

Olive orchards represent a key agricultural system in the Mediterranean Basin. Soil degradation processes associated with unsustainable agronomic practices and climate change could severely impact the sustainability of Mediterranean rainfed olive orchards. In this context, soil amendments are important tools that can be used to enhance soil fertility for sustained environmental quality and plant performance. In this study, a field trial was conducted for 4 years in olive tree (Olea europaea L.) to assess the effects of a mineral fertilizer compound and the combination with a single application of zeolites or biochar on the physiological and biochemical performance, tree nutritional status, crop yield and soil chemical and biological properties to gain knowledge towards more sustainable management. Our results showed that the addition of zeolites and biochar to mineral fertilizer ameliorated the physiological and biochemical performance, as evidenced by consistent increments of relative water content, stomatal conductance and net photosynthesis and by lower signs of oxidative stress during the periods of greater climate adversity. However, crop yield was not significantly different among soil treatments. On the other hand, soil chemical and biological traits at the surface layer (0-10 cm) have shown different and relevant responses after 4 years of soil amendment application. In fact, zeolite supply stood out as increased pH, extractable K, cation exchange capacity, microbial biomass carbon and microbial biomass quotient and reduced extractable Cu. Furthermore, zeolites induced positive changes in soil enzymatic activity, leading to increases in 10 enzymes involved in C, N and P cycles. In contrast, the effects of biochar on soil properties were much more reduced, given that it decreased the microbial biomass nitrogen and enhanced the activities of three P-cycle enzymes. In summary, our data demonstrated that both soil amendments can be an interesting complement to mineral fertilization, in order to increase trees' resilience under rainfed conditions and to promote soil health, although the use of zeolites appears to be a more promising strategy because of the induction of higher soil sustainability.

2024Journal article

Open access