Manuel Arias-Estévez

In this laboratory exercise, students explore the potential impacts of temperature and salinity on agricultural systems. Specifically, wheat seed germination was evaluated across a temperature range of 15–35 °C and in the presence or absence of sodium chloride (NaCl), thereby simulating scenarios of rising temperatures and increasing soil salinity. The primary objective of this activity was to raise students’ awareness of the challenges that climate change may pose to crop production and, consequently, to promote critical thinking about agronomic strategies that could mitigate these adverse effects. The results indicate that both root and shoot growth of wheat seedlings increase as temperature rises within the tested range. However, at elevated temperatures (35 °C), particularly under saline conditions, both root and shoot development were markedly reduced. These findings allow students to examine the interactive effects of temperature and salinity stress while connecting experimental observations to broader environmental and agricultural issues.

Soil electrical conductivity (EC) and aggregate-size distribution are critical indicators of soil salinity risk, structural integrity, and overall soil health. We assessed the status of these properties in 188 wheat plots across nine European pedoclimatic zones to quantify the influence of climate and agricultural management. Most soils (~88%) were non-saline, 9% slightly saline, and 3% moderately saline, with the highest salinity in Mediterranean regions. EC was generally lower under organic management, reflecting higher soil organic carbon, improved porosity, and enhanced cation retention. Soils were dominated by small macroaggregates (250–2000 µm) and large microaggregates (53–250 µm), together accounting for an average of 73% of total aggregates. Climate was the primary determinant of both EC and aggregate distribution, with drier and warmer conditions promoting salinization and smaller aggregate sizes, whereas wetter conditions favored macroaggregate formation. Agricultural management had a secondary but context-dependent effect, particularly on soil aggregation, with organic farming, integrated organomineral fertilization, crop residue incorporation, and legume rotations enhancing macroaggregate formation, especially in low-SOC soils. These results indicate that pedoclimatic conditions largely shape soil salinity and structure, but adopting targeted, site-specific management practices can sustain soil health and mitigate risks related to salinity and structure, particularly under projected climate change.

This study investigates the adsorption/desorption behaviour of the widely used fungicide cymoxanil in twelve acidic agricultural soils, providing the first comprehensive assessment of its retention dynamics. Cymoxanil exhibited low adsorption, with K_d(ads) values ranging from 0.57 to 4.40 L kg⁻¹ and adsorption percentages between 18.7 and 65.9% at the highest tested concentration, suggesting high mobility and bioavailability in soils and, consequently, a potential environmental and human health risk. Hysteresis was observed, with desorption percentages for the highest initial concentration ranging from 2.4% to 32.6%, indicating that part of the adsorbed compound remained relatively strongly retained. Adsorption was positively correlated with desorption parameters, reflecting a statistical association whereby soils with higher adsorption tended to exhibit lower desorption. Among soil physicochemical properties, pH appeared to play a key role in controlling cymoxanil retention, as higher pH was associated with greater adsorption and lower desorption in the studied soils. Organic matter, clay content, and exchangeable base cations also appeared to influence cymoxanil behaviour, although to a lesser extent than pH. In this regard, soils richer in organic matter and clay, and with higher effective cation exchange capacity (eCEC), tended to display greater retention. Overall, cymoxanil adsorption appears to be largely governed by physisorption mechanisms—electrostatic interactions, cation exchange, and hydrophobic partitioning—while the observed hysteresis suggests that specific interactions, such as hydrogen bonding and π-π interactions, may also contribute to retention without implying irreversible chemisorption.

The global increase in antibiotics consumption has caused hazardous concentrations of these antimicrobials to be present in soils, mainly due to the spreading of sewage sludge (or manure or slurry) and wastewater, and they could enter the food chain, posing serious risks to the environment and human health. One of these substances of concern is cefuroxime (CFX). To face antibiotics-related environmental pollution, adsorption is one of the most widely used techniques, with cost-effective and environmentally friendly byproducts being of clear interest to retain pollutants and increase the adsorption capacity of soils. In light of this, in this work, three low-cost bioadsorbents (pine bark, oak ash, and mussel shell) were added to different soil samples (at doses of 12 and 48 t/ha) to study their effects on the adsorption of CFX. Specifically, batch experiments were carried out for mixtures of soils and bioadsorbents, adding a range of different antibiotic concentrations at a fixed ionic strength. The results showed that the addition of pine bark (with pH = 3.99) increased the adsorption to 100% in most cases, while oak ash (pH = 11.31) and mussel shell (pH = 9.39) caused a clearly lower increase in adsorption (which, in some cases, even decreased). The Freundlich and linear models showed rather good adjustment to the experimental data when the bioadsorbents were added at both doses, while the Langmuir model showed error values which were too high in many cases. Regarding desorption, it was lower than 6% for the soils without bioadsorbents, and there was no desorption when the soils received bioadsorbent amendments. These results show that the addition of appropriate low-cost bioadsorbents to soils can be effective for adsorbing CFX, helping in the prevention of environmental pollution due to this emerging contaminant, which is a result of clear relevance to environmental and human health.

Civilian and military activities are sources of water and soil contamination by inorganic and organic contaminants caused by shooting practices, warfare, and/or mechanized military training. Lead poisoning and contaminant bioaccumulation due to spent shots or other related military contaminants have been widely studied for mammals, birds, and plants. Although there are different papers on the impact on earthworms, information on micro and mesofauna (i.e., collembola, nematodes, etc.) is still scarce. Here, we review the published data regarding the impact of civilian and military shooting activities, including war-impacted areas, focusing on soil organisms, from microbial communities to the ecotoxicological effects on terrestrial organisms. One hundred eleven studies were considered where earthworms and enchytraeids were widely studied, especially under ecotoxicological assays with Pb and energetic-related compounds from military explosives. There is a lack of information on soil organism groups, such as mites, ants, or gastropods, which play important roles in soil function. Data from combined exposures (e.g., PTEs + TNT and PTEs + PAHs) is scarce since several studies focused on a single contaminant, usually Pb, when combined contaminants would be more realistic. Ecotoxicological assays should also cover other understudied ammunition elements, such as Bi, Cu, or W.