Jorge Mataix-Solera

Tephra fallout deposition during volcanic eruptions overlays existing soils, profoundly altering their physical, chemical, and biological properties. This study investigates the impact of the newly deposited tephra blanket from the 2021 Tajogaite eruption (La Palma Island) on the molecular composition of soil organic matter and microbial diversity across different soil horizons. A combination of 16S and 18S rRNA gene sequencing, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and elemental and isotope ratio mass spectrometry (EA/IRMS) was employed. Our results demonstrate that tephra deposits significantly modify the organic matter composition of the underlying soils, promoting microbial activity linked to the degradation and transformation of organic carbon and nitrogen compounds. The soil horizon directly beneath the tephra layer (horizon O) displayed a higher abundance of labile organic compounds and a reduced presence of recalcitrant compounds compared to the deeper horizons (A and Bw). This pattern is strongly associated with the predominance of thermophilic bacteria, which contribute actively to the breakdown of complex organic materials such as lignin and hydrocarbons, and drive key biogeochemical processes including nitrogen and carbon cycling. The continuous geothermal influence of nearby fumaroles further supports the persistence and ecological success of thermophilic communities in these volcanic soils. These findings underscore the critical role of volcanic activity not only in reshaping soil structure but also in enhancing soil fertility and resilience through microbial-mediated processes. Understanding these dynamics is essential for soil management and ecosystem recovery strategies in volcanic regions, providing new insights into the long-term effects of tephra deposition on soil health and the carbon cycle.

Tephra fallout deposition during volcanic eruptions overlays existing soils, profoundly altering their physical, chemical, and biological properties. This study investigates the impact of the newly deposited tephra blanket from the 2021 Tajogaite eruption (La Palma Island) on the molecular composition of soil organic matter and microbial diversity across different soil horizons. A combination of 16S and 18S rRNA gene sequencing, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and elemental and isotope ratio mass spectrometry (EA/IRMS) was employed. Our results demonstrate that tephra deposits significantly modify the organic matter composition of the underlying soils, promoting microbial activity linked to the degradation and transformation of organic carbon and nitrogen compounds. The soil horizon directly beneath the tephra layer (horizon O) displayed a higher abundance of labile organic compounds and a reduced presence of recalcitrant compounds compared to the deeper horizons (A and Bw). This pattern is strongly associated with the predominance of thermophilic bacteria, which contribute actively to the breakdown of complex organic materials such as lignin and hydrocarbons, and drive key biogeochemical processes including nitrogen and carbon cycling. The continuous geothermal influence of nearby fumaroles further supports the persistence and ecological success of thermophilic communities in these volcanic soils. These findings underscore the critical role of volcanic activity not only in reshaping soil structure but also in enhancing soil fertility and resilience through microbial-mediated processes. Understanding these dynamics is essential for soil management and ecosystem recovery strategies in volcanic regions, providing new insights into the long-term effects of tephra deposition on soil health and the carbon cycle.

Tephra fallout deposition during volcanic eruptions overlays existing soils, profoundly altering their physical, chemical, and biological properties. This study investigates the impact of the newly deposited tephra blanket from the 2021 Tajogaite eruption (La Palma Island) on the molecular composition of soil organic matter and microbial diversity across different soil horizons. A combination of 16S and 18S rRNA gene sequencing, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and elemental and isotope ratio mass spectrometry (EA/IRMS) was employed. Our results demonstrate that tephra deposits significantly modify the organic matter composition of the underlying soils, promoting microbial activity linked to the degradation and transformation of organic carbon and nitrogen compounds. The soil horizon directly beneath the tephra layer (horizon O) displayed a higher abundance of labile organic compounds and a reduced presence of recalcitrant compounds compared to the deeper horizons (A and Bw). This pattern is strongly associated with the predominance of thermophilic bacteria, which contribute actively to the breakdown of complex organic materials such as lignin and hydrocarbons, and drive key biogeochemical processes including nitrogen and carbon cycling. The continuous geothermal influence of nearby fumaroles further supports the persistence and ecological success of thermophilic communities in these volcanic soils. These findings underscore the critical role of volcanic activity not only in reshaping soil structure but also in enhancing soil fertility and resilience through microbial-mediated processes. Understanding these dynamics is essential for soil management and ecosystem recovery strategies in volcanic regions, providing new insights into the long-term effects of tephra deposition on soil health and the carbon cycle.

The intensive use of pesticides in agriculture has generated significant ecological impacts, particularly in rice ecosystems, where soil biodiversity plays an essential role in the stability and productivity of agroecosystems. This study presents a systematic review of the evidence regarding the ef fects of pesticides on soil biodiversity in rice cultivation systems. The impacts on microorganisms, earthworms, and nematodes were evaluated, together with reported sustainable mitigation strategies. The review was conducted following the PRISMA methodology and included 43 studies published between 2011 and February 2025 from Latin America, Europe, Asia, and Africa. The results revealed that the recurrent use of pesticides such as chlorpyrifos, DDT, and glyphosate significantly altered the abundance, diversity, and ecological functions of soil organisms, thereby af fecting soil fertility, structure, and health. These ef fects were more pronounced in tropical regions, where climatic conditions and agricultural practices increase the persistence and toxicity of these compounds. Mitigation strategies identified included bioremediation, crop rotation, composting, integrated pest management, and the use of biofertilizers. The review also highlights the emerging role of stricter regulatory frameworks and agroecological approaches as viable alternatives. Overall, the findings underscore the urgent need to adopt sustainable agricultural practices that protect soil biodiversity and enhance the resilience of agricultural production systems.

Global change is altering fire regimes worldwide, exposing fire-sensitive ecosystems such as Patagonia’s to unprecedented fire sizes and frequencies, which can result in irreversible soil degradation. A megafire in Torres del Paine National Park (Chile, 2011-2012) created a mosaic of burn severities across contrasting fire-sensitive ecosystems. This setting provided an opportunity to evaluate medium-term post-fire effects on soil organic matter (SOM) stabilization. We assessed the effects of fire occurrence and burn severity across 34 plots within two cold climatic conditions and six vegetation types. Soils were fractionated into free particulate organic matter (fPOM), occluded particulate organic matter (oPOM) and mineral-associated organic matter (MAOM). Chemical composition of fPOM and oPOM was characterized by solid-state 13C CPMAS NMR spectroscopy, whereas MAOM was characterized by ATR-FTIR spectroscopy. Post-fire analysis revealed that MAOM showed no compositional differences between fire occurrence or burn severity. In contrast, fPOM and oPOM showed clear fire legacies, with high pyrogenic carbon and low carbohydrates in burned soils, especially in fPOM. Burn severity had limited effects on SOM composition, but nominal oxidation state of carbon (NOSC) was significantly increased, suggesting thermodynamic changes rather than chemical composition shifts. Negative associations between carbohydrates and parameters like stable aggregates and microbial biomass indicated that fire-related changes in labile and physically protected SOM pools may influence medium-term soil functioning. Our results highlight the differential sensitivity of SOM fractions to wildfire in fire-sensitive Patagonian ecosystems and underline the importance of particulate organic matter dynamics for understanding post-fire soil vulnerability and recovery.

Tephra fallout deposition during volcanic eruptions overlays existing soils, profoundly altering their physical, chemical, and biological properties. This study investigates the impact of the newly deposited tephra blanket from the 2021 Tajogaite eruption (La Palma Island) on the molecular composition of soil organic matter and microbial diversity across different soil horizons. A combination of 16S and 18S rRNA gene sequencing, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and elemental and isotope ratio mass spectrometry (EA/IRMS) was employed. Our results demonstrate that tephra deposits significantly modify the organic matter composition of the underlying soils, promoting microbial activity linked to the degradation and transformation of organic carbon and nitrogen compounds. The soil horizon directly beneath the tephra layer (horizon O) displayed a higher abundance of labile organic compounds and a reduced presence of recalcitrant compounds compared to the deeper horizons (A and Bw). This pattern is strongly associated with the predominance of thermophilic bacteria, which contribute actively to the breakdown of complex organic materials such as lignin and hydrocarbons, and drive key biogeochemical processes including nitrogen and carbon cycling. The continuous geothermal influence of nearby fumaroles further supports the persistence and ecological success of thermophilic communities in these volcanic soils. These findings underscore the critical role of volcanic activity not only in reshaping soil structure but also in enhancing soil fertility and resilience through microbial-mediated processes. Understanding these dynamics is essential for soil management and ecosystem recovery strategies in volcanic regions, providing new insights into the long-term effects of tephra deposition on soil health and the carbon cycle.

Abbas et al. assess the effects of biochar (3%) combined with compost and animal manure (0.5-1%) on soil carbon fractions, soil properties, and maize growth in lowfertility soil. Biochar combined with 1% compost significantly improved plant growth, soil organic matter, microbial biomass, and the carbon pool index. The findings highlight organic amendments as a sustainable strategy to restore degraded soils, enhance crop productivity, and support a circular economy under changing climate conditions. Reyes-Sánchez. examines soil science as an asset for interdisciplinary teaching approaches aimed at fostering values, scientific interest, and environmental responsibility in primary school children. Building on a previous methodological proposal, the study integrates knowledge construction with value formation through a playful, qualitative pedagogical strategy applied to 5th and 6th grade students. It compares children's perceptions of social, political, and environmental issues before and after the intervention, highlighting the role of science education in promoting sustainability-oriented attitudes.Altés et al. analyse salt dynamics and drainage loads in a newly established irrigation district in the Ebro basin (NE Spain) during 2021-2023, including the severe 2023 drought. Monitoring two sub-basins showed that a 31% reduction in irrigation delivery led to a 73% decrease in drainage and a 70% reduction in salt exports. The results highlight the potential of irrigation restrictions to improve water and salt management, while also revealing associated yield losses.Quintana-Esteras evaluate the effects of prescribed burning and selective shrub clearing on subalpine soils and vegetation in the Central Pyrenees. Both treatments similarly increased soil pH and reduced several physical and chemical properties, while microbial functional diversity remained stable. Mechanical clearing enhanced soil microbial activity compared to burning. Two years after intervention, shrub cover remained low in both treatments, although prescribed burning resulted in more bare soil and reduced plant diversity than selective clearing.Aguirre-Arcos et al. assess sap analysis as a rapid tool to diagnose the nutritional status of olive trees under integrated production in southern Spain. Trials across five farms showed clear seasonal nutrient fluxes in sap, influenced by climate and phenology. Comparisons among sap, leaf, and soil analyses highlighted potassium dominance in sap and climate-driven micronutrient variability. The results indicate that sap analysis complements traditional methods, supporting more precise and balanced fertilization strategies in olive orchards.Usón Murillo et al. analyse initiatives to harmonize soil analytical methods in Spain through interlaboratory proficiency tests promoted by the Spanish Society of Soil Science (SECS) and partner institutions. Results from tests in 2019 and 2021 revealed significant methodological differences among laboratories, with partial improvements in performance and persistent weaknesses, particularly in organic matter and texture analyses. The study highlights the need for regular proficiency testing to improve analytical quality and ensure reliable soil data for sustainable soil management and policy implementation.Pérez Moreira and Barral Silva in their article explore the rare but significant representation of soil in Western landscape painting. It identifies periods of naturalistic art, particularly in 17th-century Dutch painting and 19th-century European landscape schools, when artists depicted soils with unusual detail. Some works reveal recognizable soil horizons and features that can be interpreted using modern soil science. The study contextualizes these artistic representations historically and culturally, highlighting intersections between art, observation of nature, and soil knowledge.Barreiro et al. study evaluates the influence of tree species on soil properties and microbial activity in 54 forest plantations in Galicia, NW Spain. Soils were generally acidic with high organic matter and low phosphorus contents. Moisture varied by vegetation: the driest soils under eucalyptus and birch, and the wettest under shrublands. Microbial respiration was highest in walnut soils and lowest in eucalyptus, while β-glucosidase activity remained unchanged. Results highlight that forest management, particularly tree species selection, affects soil microbial function and carbon stabilization, with implications for climate-adaptive forestry planning.The special issue concludes with the study of Tierra et al. who investigate soil salinity in the rainfed landscapes of the "Saladas of Sástago-Bujaraloz" in the Central Ebro Basin, Spain. Analyses of 319 soil samples and electromagnetic sensor readings revealed highly variable and often extreme salinity, with 73% of samples very strongly saline. Vertical and horizontal variability was observed, with best electro-magnetic sensor readings correlations at 0-100 cm depth. The authors propose incorporating soil salinity as an agronomic criterion within the EU Common Agricultural Policy, recommending the exclusion of plots with ECe > 10 dS m-1, representing more than half of their study area.

Tephra fallout deposition during volcanic eruptions overlays existing soils, profoundly altering their physical, chemical, and biological properties. This study investigates the impact of the newly deposited tephra blanket from the 2021 Tajogaite eruption (La Palma Island) on the molecular composition of soil organic matter and microbial diversity across different soil horizons. A combination of 16S and 18S rRNA gene sequencing, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and elemental and isotope ratio mass spectrometry (EA/IRMS) was employed. Our results demonstrate that tephra deposits significantly modify the organic matter composition of the underlying soils, promoting microbial activity linked to the degradation and transformation of organic carbon and nitrogen compounds. The soil horizon directly beneath the tephra layer (horizon O) displayed a higher abundance of labile organic compounds and a reduced presence of recalcitrant compounds compared to the deeper horizons (A and Bw). This pattern is strongly associated with the predominance of thermophilic bacteria, which contribute actively to the breakdown of complex organic materials such as lignin and hydrocarbons, and drive key biogeochemical processes including nitrogen and carbon cycling. The continuous geothermal influence of nearby fumaroles further supports the persistence and ecological success of thermophilic communities in these volcanic soils. These findings underscore the critical role of volcanic activity not only in reshaping soil structure but also in enhancing soil fertility and resilience through microbial-mediated processes. Understanding these dynamics is essential for soil management and ecosystem recovery strategies in volcanic regions, providing new insights into the long-term effects of tephra deposition on soil health and the carbon cycle.

Background and Aims: Wildfires in high-altitude dry shrublands of the Peruvian Andes are increasingly becoming a significant ecological threat, with substantial and potentially persistent impacts on soils. This study investigated how fire affects soil microbial communities and functions beneath two dominant shrub species, Berberis lutea and Parastrephia quadrangularis , which differ in biomass and fuel structure and therefore in the intensity of combustion that their soils are exposed to. We hypothesized that fire would modify microbial community composition, biomass and functional activity, leading to distinct recovery trajectories beneath the two shrub species due to their contrasting fuel characteristics. Methods: We conducted a medium-term assessment (3–4 years post-fire) of soil microbial structure and activity using phospholipid fatty acids (PLFA), microbial respiration, microbial biomass carbon and enzyme activities. Results: Fire effects on soils were species-specific. Soils beneath P. quadrangularis showed greater potential for bacterial and fungal communities recovery, while those under B. lutea soils were more severely affected, likely due to higher aboveground biomass. Despite these differences, both species experienced a strong and persistent reduction in enzymatic activities, indicating long-lasting impacts on soil functionality. In addition, soil properties such as aggregate stability and water repellency were identified as key factors associated with microbial recovery. Conclusions: The results reveal the high vulnerability of Andean dryland soils to wildfire and highlight the role of vegetation type in determining post-fire microbial recovery. Incorporating soil biological indicators into post-fire restoration planning and soil vulnerability assessment may help reduce long-term degradation risks in these fragile high-altitude ecosystems. Graphical

Tephra fallout deposition during volcanic eruptions overlays existing soils, profoundly altering their physical, chemical, and biological properties. This study investigates the impact of the newly deposited tephra blanket from the 2021 Tajogaite eruption (La Palma Island) on the molecular composition of soil organic matter and microbial diversity across different soil horizons. A combination of 16S and 18S rRNA gene sequencing, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and elemental and isotope ratio mass spectrometry (EA/IRMS) was employed. Our results demonstrate that tephra deposits significantly modify the organic matter composition of the underlying soils, promoting microbial activity linked to the degradation and transformation of organic carbon and nitrogen compounds. The soil horizon directly beneath the tephra layer (horizon O) displayed a higher abundance of labile organic compounds and a reduced presence of recalcitrant compounds compared to the deeper horizons (A and Bw). This pattern is strongly associated with the predominance of thermophilic bacteria, which contribute actively to the breakdown of complex organic materials such as lignin and hydrocarbons, and drive key biogeochemical processes including nitrogen and carbon cycling. The continuous geothermal influence of nearby fumaroles further supports the persistence and ecological success of thermophilic communities in these volcanic soils. These findings underscore the critical role of volcanic activity not only in reshaping soil structure but also in enhancing soil fertility and resilience through microbial-mediated processes. Understanding these dynamics is essential for soil management and ecosystem recovery strategies in volcanic regions, providing new insights into the long-term effects of tephra deposition on soil health and the carbon cycle.