Maria Cristina O. Oliveira

This study investigates the impact of organic (OF) and conventional farming (CF) on soil fungal communities in banana monoculture plantations on Madeira Island. We hypothesized that OF promotes beneficial fungal groups over harmful ones, sustaining soil health. Soil samples were collected from six plantations (three OF and three CF) for ITS amplicon sequencing to assess fungal diversity. Results showed that OF significantly enhanced fungal alpha-diversity (Shannon–Wiener index) and Evenness. The phylum Ascomycota dominated OF systems, while Basidiomycota prevailed in CF. Mortierella, a beneficial genus, was abundant in OF and is observed in CF but was less evident, being the genus Trechispora the most well represented in CF agrosystems. Additionally, OF was associated with higher soil pH and Mg levels, which correlated positively with beneficial fungal groups. Functional analysis revealed that OF promoted saprotrophic fungi, crucial for the decomposition of organic matter and nutrient cycling. However, both systems exhibited low levels of arbuscular mycorrhizal fungi, likely due to high phosphorus levels. These findings suggest that organic practices can enhance soil fungal diversity and health, although attention to nutrient management is critical to further improving soil–plant–fungi interactions.

Agricultural soils are responsible for ecological functions and services that include primary production of food, fiber and fuel, nutrient cycling, carbon cycling and storage, water infiltration and purification, among others. Fungi are important drivers of most of those ecosystem services. Given the importance of fungi in agricultural soils, in this study, we aimed to characterize and analyse the changes of the soil fungal communities of three cropping systems from Madeira Island, where family farming is predominant, and investigate the response of fungi and its functional groups to soil physicochemical properties. To achieve that, we sequenced amplicons targeting the internal transcribed spacer 1 (ITS1) of the rRNA region, to analyse soil samples from 18 agrosystems: 6 vineyards (V), 6 banana plantations (B) and 6 vegetable plantations (H). Our results showed that alpha diversity indices of fungal communities are similar in the three cropping systems, but fungal composition and functional aspects varied among them, with more pronounced differences in B. Ascomycota, Basidiomycota, and Mortierellomycota were the main phyla found in the three cropping systems. Agaricomycetes and Sordariomycetes are the predominant classes in B, representing 23.8 and 22.4%, respectively, while Sordariomycetes (27.9%) followed by Eurotiomycetes (12.3%) were the predominant classes in V and Sordariomycetes (39.2%) followed by Tremellomycetes (8.9%) in the H. Saprotrophs are the fungal group showing higher relative abundance in the three cropping systems, followed by plant pathogens. Regarding symbionts, endophytes were highly observed in B, while mycorrhizal fungi was predominant in V and H. The structure of fungal communities was mainly correlated with soil content of P, K, N, Fe, and Cu. In addition, we identified bioindicators for each cropping system, which means that cultivated crops are also drivers of functional groups and the composition of communities. Overall, the three cropping systems favored diversity and growth of taxa that play important roles in soil, which highlights the importance of conservative management practices to maintain a healthy and resilient agrosystem.

Climate—Madeira Strategy (CMS) foresees two models to describe the climate scenarios for the Madeira region in 2050 and 2070. These scenarios anticipate an average temperature rise of 1.4 to 3.7 °C and a decrease in precipitation by 30 to 40%. Consequently, Madeira’s agriculture will suffer the impacts of climate change. To understand these impacts, a baseline of major agrosystem components needs to be established, with the ultimate goal to monitor its consequences in its functioning. CASBio project used the 1961–1991 and 2010–2020 meteorological data series to modulate climate conditions and characterize and monitor six agrosystems for 2 years. One of them was a vineyard, Quinta das Vinhas, representing a typical agrosystem in the Mediterranean climate. The annual and seasonal variation in climatic parameters, soil conditions, microbiological communities, floristic and insect diversity, and crop production was assessed, using a total of 50 parameters. The results were used to establish a baseline of the agrosystem components and their seasonal and annual variation. The major findings are: (i) winter and summer extreme events show a trend in temperature and precipitation supporting a fast change in climate; (ii) a critical imbalance between nitrogen-fixing and denitrifying bacteria was identified, especially in summer, that could be determined by the rise in temperature and drought; (iii) among floristic diversity, the therophytes and geophytes confirm to be the most suitable indicators for the rise in temperature and reduction in precipitation in the agrosystems; (iv) an imbalance in favor of C. capitata plague was observed, associated with the summer rise in temperature and decrease in precipitation; (v) despite an increase in most of the grape varieties production, the Madeiran wine local varieties were shown to be less stable in productivity under observed climate conditions. The agrosystem baseline is a starting point for long-term monitoring and allows for further quantifying the influence of climate change on agrosystem productivity, resilience, and sustainability.

Sewage sludge (SS) is derived from wastewater treatment plants and can be used as a biofertilizer when properly stabilized. This work aimed to evaluate SS application for agricultural production improvement. SS was tested on Porto Santo Island (Portugal). The experiment was randomly designed with three 25 m² plots for each treatment (2 SS concentrations + control without SS) and performed in two consecutive cycles. For the first cycle, dehydrated sludge was mixed with soil, obtaining final concentrations of 0.8 kg/m² (C1) and 1.6 kg/m² (C2). Half of the concentration was used for the second cycle. Fifty-eight sweet potato plants were used in each plot. SS application boosted the agronomic parameters of biomass, productivity, and shoot biomass. Furthermore, improvements in soil properties were observed, mainly for pH, CEC, and NO₃-N, with no significant increase in heavy metals. For the edible parts, heavy metal concentrations decreased, and Pb was the only one that still exceeded the maximum limits. The results demonstrated that SS application to low-fertility soil is effective in improving the agronomic parameters of sweet potato and enhancing soil features. Further studies considering other variables, i.e., SS origin, soil properties, and the crop, must be carried out to propose custom applications.