A Legacy Written in Soil: Special Issue Honors Spanish Soil Scientist Jaume Porta Casanellas

Soil is easy to overlook. It sits beneath our feet, silent and seemingly inert, yet it governs the food we eat, the water we drink, and the climate we live in. Few people understood this better than Jaume Porta Casanellas, one of the most influential figures in Spanish soil science, who passed away in September 2023, only days after actively participating in the XXXII National Meeting of Soils, known as RENS2023, held in Navarre, Spain. That congress became his last scientific gathering, and now the Spanish Journal of Soil Science has dedicated a special issue to his memory, gathering a remarkable collection of studies that reflect both his enduring influence and the extraordinary breadth of the discipline he championed throughout his career.

The editorial, published in Volume 16 of the journal, was written by Alberto Enrique, Íñigo Virto, Avelino Núñez Delgado, Jorge Mataix-Solera, and Irene Ortiz-Bernad, researchers affiliated with Spanish universities including the Universidad Pública de Navarra, the Universidade de Santiago de Compostela, the Universidad Miguel Hernández de Elche, and the Universidad de Granada. They describe a scientist whose legacy was simultaneously scientific, educational, and institutional. Porta was a co-founder and Secretary of the Editorial Board of the Spanish Journal of Soil Science and served as President of the Spanish Society of Soil Science, an organization known by its Spanish acronym SECS. Perhaps most notably, he worked tirelessly to strengthen the connections between the Spanish and Latin American Soil Science Societies, building bridges across the Atlantic at a time when such collaboration was far from routine.

The special issue opens with a contribution by Alcañiz and colleagues that gathers personal and professional reflections from disciples, colleagues, and friends of Porta, offering an intimate portrait of a career that shaped generations of soil scientists. The tribute article reviews his pioneering work on salt-affected soils and gypsum-rich soils, two notoriously difficult materials that demand specialized analytical approaches, along with his contributions to soil mapping and the standardization of laboratory methods. Special emphasis is placed on his textbooks, which became foundational references for Spanish-speaking students, and on his international training initiatives that carried rigorous soil education far beyond Spain’s borders. His role in strengthening scientific institutions, journals, and the public dissemination of soil knowledge emerges as a defining thread of the tribute.

From this personal opening, the issue pivots to the kind of applied research Porta championed. Abbas and colleagues assessed the effects of biochar applied at three percent, combined with compost and animal manure at concentrations between 0.5 and 1 percent, on soil carbon fractions, soil properties, and maize growth in low-fertility soil. The results were striking: biochar combined with one percent compost significantly improved plant growth, soil organic matter, microbial biomass, and the carbon pool index, a metric that tracks how effectively soil stores and protects carbon. In an era when agriculture is under pressure to rebuild degraded soils while feeding a growing population, the findings position organic amendments as a sustainable strategy that simultaneously enhances crop productivity and supports a circular economy under changing climate conditions.

Water and salt management, topics close to Porta’s own research on salt-affected soils, feature prominently in the issue. Altés and colleagues analyzed salt dynamics and drainage loads in a newly established irrigation district in the Ebro basin in northeastern Spain between 2021 and 2023, a period that included the severe drought of 2023. By monitoring two sub-basins, the researchers found that a 31 percent reduction in irrigation delivery produced a 73 percent decrease in drainage and a 70 percent reduction in salt exports. The numbers carry a double message. On one hand, irrigation restrictions can dramatically improve water and salt management, preventing the salinization that has ruined farmland since antiquity. On the other hand, the restrictions came with associated yield losses, a reminder that every water management decision involves trade-offs between conservation and production.

Fire and vegetation management were also on the agenda. Quintana-Esteras and colleagues evaluated the effects of prescribed burning and selective shrub clearing on subalpine soils and vegetation in the Central Pyrenees, two techniques widely used to control shrub encroachment in mountain pastures. Both treatments similarly increased soil pH and reduced several physical and chemical properties, while microbial functional diversity remained stable, suggesting a degree of resilience in the soil microbial community. However, mechanical clearing enhanced soil microbial activity compared to burning, and two years after the interventions, shrub cover remained low in both treatments, although prescribed burning resulted in more bare soil and reduced plant diversity than selective clearing. For land managers weighing these options, the study offers a nuanced picture in which the gentler mechanical approach appears to preserve more of the ecosystem’s biological fabric.

Precision agriculture takes center stage in the work of Aguirre-Arcos and colleagues, who assessed sap analysis as a rapid diagnostic tool for the nutritional status of olive trees under integrated production in southern Spain. Across trials on five farms, the researchers documented clear seasonal nutrient fluxes in the sap, shaped by climate and the trees’ phenological stages. Comparisons among sap, leaf, and soil analyses highlighted the dominance of potassium in sap and revealed climate-driven variability in micronutrients. The technique does not replace traditional methods, but it complements them, supporting more precise and balanced fertilization strategies in olive orchards, an economically vital crop in the Mediterranean where over-fertilization wastes resources and under-fertilization erodes yields.

Two contributions underscore the cultural and institutional dimensions of soil science, areas where Porta’s influence was profound. Usón Murillo and colleagues analyzed initiatives to harmonize soil analytical methods in Spain through interlaboratory proficiency tests promoted by the Spanish Society of Soil Science and partner institutions. Results from tests conducted in 2019 and 2021 revealed significant methodological differences among laboratories, with only partial improvements in performance and persistent weaknesses, particularly in organic matter and texture analyses. The study makes a compelling case for regular proficiency testing, arguing that reliable soil data underpin sustainable soil management and effective policy implementation. Without comparable measurements, soil data cannot be aggregated, compared, or trusted at regional or national scales.

In an unexpected turn, Pérez Moreira and Barral Silva explored the rare but significant representation of soil in Western landscape painting, identifying periods of naturalistic art, particularly seventeenth-century Dutch painting and the nineteenth-century European landscape schools, when artists depicted soils with unusual detail. Some of these works reveal recognizable soil horizons and features that can be interpreted using modern soil science, effectively turning canvases into historical soil archives. The study contextualizes these artistic representations historically and culturally, illuminating the intersections between art, the observation of nature, and soil knowledge, and demonstrating that the scientific and humanistic study of land are not separate endeavors but parallel ways of reading the same surface.

The issue closes with two studies that tie the threads together. Barreiro and colleagues examined the influence of tree species on soil properties and microbial activity across 54 forest plantations in Galicia, northwestern Spain, finding generally acidic soils with high organic matter and low phosphorus contents. Moisture varied by vegetation, with the driest soils under eucalyptus and birch and the wettest under shrublands, while microbial respiration was highest in walnut soils and lowest under eucalyptus. The results carry direct implications for climate-adaptive forestry planning, since tree species selection shapes soil microbial function and carbon stabilization. Finally, Tierra and colleagues investigated soil salinity in the rainfed landscapes of the Saladas of Sástago-Bujaraloz in the Central Ebro Basin, analyzing 319 soil samples alongside electromagnetic sensor readings. They found highly variable and often extreme salinity, with 73 percent of samples classified as very strongly saline, and the strongest sensor correlations at depths of 0 to 100 centimeters. Their proposal to incorporate soil salinity as an agronomic criterion within the EU Common Agricultural Policy, recommending the exclusion of plots with electrical conductivity above 10 dS per meter, a threshold exceeded across more than half of their study area, shows how the science Porta devoted his life to can flow directly into European policy. Together, these contributions form a fitting memorial: a portrait of soil science as a living, interdisciplinary enterprise, from laboratory benches and olive groves to mountain forests, museum walls, and the halls of Brussels.

Subject of Research: A memorial special issue of Spanish soil science research honoring soil scientist Jaume Porta Casanellas

Article Title: Editorial: Jaume Porta Casanellas – RENS Soil Science

Article References: Enrique, A., Virto, Í., Delgado, A. N., Mataix-Solera, J., & Ortiz-Bernad, I. (2026). Editorial: Jaume Porta Casanellas – RENS Soil Science. Spanish Journal of Soil Science, 16, Article 16319. https://doi.org/10.3389/sjss.2026.16319

Image Credits: AI Generated

DOI: 10.3389/sjss.2026.16319

Keywords: soil science, Jaume Porta Casanellas, Spanish Journal of Soil Science, soil salinity, biochar, soil organic matter, prescribed burning, olive trees, interlaboratory proficiency testing, forest soils, soil education, Ebro basin