Carlos Alberto Torres-Guerrero

Mediterranean agroecosystems are highly vulnerable to climate change, soil degradation, and declining soil organic carbon (SOC), threatening long-term agricultural sustainability. Carbon farming and regenerative agriculture have emerged as complementary approaches to restore soil functionality while contributing to climate change mitigation. This review synthesizes peer-reviewed literature published between 2015 and 2025 to assess the agronomic effectiveness of key regenerative and carbon farming practices in Mediterranean systems. A structured bibliographic analysis using Scopus and Web of Science evaluated practices influencing SOC dynamics, erosion control, water regulation, and associated ecosystem services. Evidence indicates that the introduction of cover crops in the crop rotation and reduced or no-tillage are the most consistently effective practices for enhancing SOC stocks, particularly when combined with organic amendments and diversified rotations. Crop diversification, intercropping, and agroforestry further support SOC accumulation and erosion control, especially in perennial systems such as vineyards and olive orchards. Organic inputs stimulate microbial-mediated carbon stabilization, while regenerative grazing contributes to nutrient cycling under context-specific conditions. Across practices, integrated management consistently delivers greater and more stable benefits than single interventions. Regenerative agriculture thus provides a systems-based foundation for carbon farming in Mediterranean agroecosystems. Long-term field experiments and improved monitoring frameworks remain essential to quantify carbon persistence and support policy implementation.

Bio-based fertilisers (BBFs) are gaining attention as sustainable alternatives to mineral fertilisers due to their potential for nutrient recovery, reduced environmental emissions, and improved soil health. However, their broader adoption is hindered by regulatory uncertainty, quality inconsistencies, and methodological variability in assessing their environmental impacts. This study can reveal about the body of research on bio-based fertilisers (BBFs), using a hybrid methodology that combines bibliometric and content analysis. A total of 247 publications from 2001 to 2024 were reviewed to identify research trends, environmental concerns, and assessment approaches. Results show a sharp increase in BBF-related publications after 2016, driven primarily by European and North American research, with growing focus on life cycle assessment (LCA) and nutrient recovery. The in-depth analysis of the ten most cited LCA and non-LCA studies highlights key methodological differences: non-LCA studies frequently rely on empirical fieldwork and generate primary data, whereas LCA studies typically synthesise secondary data to provide broader system-level insights. Despite this complementarity, the lack of methodological harmonisation poses a barrier to consistent comparison and interpretation. The findings highlight the need for a unified, standardised assessment framework to reliably evaluate the environmental performance of BBFs and support their effective implementation within circular and sustainable agricultural systems.

Loess–palaeosol sequences (LPSs) are continuous records of palaeoenvironmental and palaeoclimatic conditions during the Quaternary. This study includes 17 LPS located in the NE of the Iberian Peninsula, irregularly distributed, associated with different river basins: the Ebro Basin, the Mora Basin, and the Ter sub-basin. The soils developed on these loess deposits present a loam–sandy texture, coarser than the typical loess, ochre in colour, with variable thickness (1–12 m), calcareous composition (20–45% CaCO₃ eq.), very low or null organic matter (OM), and basic pH. These deposits have been classified as desert LPS, whose pedogenesis is mainly associated with the redistribution of calcium carbonate and, in some cases, gypsum. Several methodologies have been applied to determine their mineralogical, physical, and chemical characteristics and date them by luminescence techniques. In addition, some relevant pedofeatures (porosity, CaCO₃, gypsum, etc.) have been characterised in detail. The aims of the present study have been to know the pedogenic development of the LPS by defining the main soil-forming factors that have affected them in order to associate these factors with the characteristic palaeoclimatic and palaeoenvironmental conditions reported in this area over time and to improve the understanding of soil evolution.

Several types of secondary carbonate accumulations have been reported, but some of them are not completely well defined in the field due to unclear nomenclature. This is the case of the “queras”, reported in several Loess-palaeosol sequences of the Ebro Valley, which have often been described as pseudomycelia. Micromorphologically, they are complex pedofeatures (including calcified root cells, infillings and hypocoatings of carbonates and a decarbonated zone), resulting from calcification/decalcification processess at a microscale. They are composed of a central channel (1-2 mm wide and 2-3 cm long) filled with biosparite crystals (Herrero et al., 1992). The study of these secondary carbonate bioaccumulations are important archives for climatic reconstructions in terrestrial environments and can be used for paleoenvironmental reconstructions. The aims of this research are the characterization (morphological, optical and isotopically) of the biocalcifications present in Loess-palaeosols sequences, OSL-dated, to determine the main factors that originate them and their possible use as a palaeoenvironmental proxy. We collected soil samples from seven profile of Loess-palaeosols where the presence of these biocalcifications was recorded. We isolated and manually cleaned complete fragments of queras to describe them and to determine their isotopic composition. For that purpose, we used the queras fraction (sieved fraction of bulk soil between 100-250 µm) removing the residues of micrite with a buffer solution and manually separating the quera fragments with the help of a stereoscope. Thin sections were made to analyse the micromorphology in a petrographic microscope and cathodoluminescence techniques to determine the origin of the calcite. The micromorphology of these biocalcifications is similar in most cases: they present the same number of rows around the central channel (4 to 5), and a decarbonated hypocoating around it, supporting the hypothesis that their origin is derived from the calcification of cells of the root tips as a strategy to acidify the soil surrounding to absorb nutrients. Under cathodoluminescence biosparite has a different behaviour than non-biological calcite crystals. The age of the queras was similar in most horizons and their formation is independent of the age of the loess deposit. The isotopic composition of δ13C correspond mainly to CAM plants and the temperatures of precipitation calculated correspond to a Mediterranean template climate (Cerling and Quade, 1993), implying that the biocalcifications developed in warm environments. Finally, we hope to gain some more certainty of their origin and formation processes from the ongoing analyses of DNA sequencing and pollen recording.

In December 2019, the first cases of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were identified in the city of Wuhan, China. Since then, it has spread worldwide with new mutations being reported. The aim of the present study was to monitor the changes in genetic diversity and track non-synonymous substitutions (dN) that could be implicated in the fitness of SARS-CoV-2 and its spread in different regions between December 2019 and November 2020. We analyzed 2213 complete genomes from six geographical regions worldwide, which were downloaded from GenBank and GISAID databases. Although SARS-CoV-2 presented low genetic diversity, there has been an increase over time, with the presence of several hotspot mutations throughout its genome. We identified seven frequent mutations that resulted in dN substitutions. Two of them, C14408T>P323L and A23403G>D614G, located in the nsp12 and Spike protein, respectively, emerged early in the pandemic and showed a considerable increase in frequency over time. Two other mutations, A1163T>I120F in nsp2 and G22992A>S477N in the Spike protein, emerged recently and have spread in Oceania and Europe. There were associations of P323L, D614G, R203K and G204R substitutions with disease severity. Continuous molecular surveillance of SARS-CoV-2 will be necessary to detect and describe the transmission dynamics of new variants of the virus with clinical relevance. This information is important to improve programs to control the virus.