Search Results (47)

This study aimed to determine the stress mechanisms induced by foliar methyl jasmonate (MeJA) application in Vaccinium corymbosum cultivars subjected to water deficit (WD) and aluminum toxicity (Al). Two V. corymbosum cultivars, Star and Legacy, were subjected to different treatments in an Andisol: control (80% field capacity and low Al saturation), combined WD + Al (50% field capacity and 85% Al saturation), and different concentrations of foliar MeJA application (10 μM, 50 μM, and 100 μM) under WD + Al conditions. The determination of photosynthetic pigments, osmolytes, and organic acids, as well as the auxin levels and the expression of Aluminium-Activated Malate Transporter (ALMT) and Multidrug and Toxic Compound Extrusion (MATE) genes, was analyzed at 7 and 21 days. Foliar MeJA application increased chlorophyll a, b, and carotenoid levels, mainly at 50 µM, exhibiting early Star responses with up to 1.5-fold higher pigment accumulation, and a later increase in Legacy with up to 1.4-fold higher accumulation. Proline increases up to 2.2-fold in roots and sugar by 1.4-fold in leaves of both cultivars. The MeJA application increases the auxin levels by up to 2.3-fold in Star roots at 7 days and by up to 1.4-fold in Legacy leaves at 21 days. MeJA-induced upregulation of ALMT and MATE gene expression facilitated Al detoxification, with malate and citrate levels increasing up to 2-fold. Hierarchical clustering confirmed that the Star cultivar activated resistance mechanisms early, while the Legacy cultivar exhibited delayed but sustained resistance mechanisms. MeJA improves V. corymbosum resistance to combined WD + Al stress by modulating photosynthetic pigments, osmolytes, organic acids, and hormone regulation. This finding underscores the biotechnological potential of MeJA application to improve stress resilience and optimize crop performance under adverse environmental conditions. Full article

The Bilbao parish, located on the slopes of the Tungurahua volcano (Ecuador), was heavily impacted by ashfall during eruptions between 1999 and 2016. Volcanic ash may contain toxic metals such as Pb, Cd, Hg, As, and Se, which are linked to neurological, renal, skeletal, pulmonary, and dermatological disorders. This study evaluated metal concentrations in soil (40–50 cm depth, corresponding to the rooting zone of forage grasses), forage (English ryegrass and Kikuyu grass), and raw milk to assess potential risks to livestock and human health. Sixteen georeferenced sites were selected using a simple random probabilistic sampling method considering geological variability, vegetation cover, accessibility, and cattle presence. Samples were digested and analyzed with a SpectrAA 220 atomic absorption spectrophotometer (Varian Inc., Victoria, Australia). Soils (Andisols) contained Hg (1.82 mg/kg), Cd (0.36 mg/kg), As (1.36 mg/kg), Pb (1.62 mg/kg), and Se (1.39 mg/kg); all were below the Ecuadorian limits, except for Hg and Se. Forage exceeded FAO thresholds for Pb, Cd, As, Hg, and Se. Milk contained Pb, Cd, and Hg below detection limits, while Se averaged 0.047 mg/kg, exceeding water safety guidelines. Findings suggest soils act as sources with significant bioaccumulation in forage but limited transfer to milk. Although immediate consumer risk is low, forage contamination highlights long-term hazards, emphasizing the need for monitoring, soil management, and farmer guidance. Full article

Natural radionuclides (⁴⁰K, ²¹⁰Pb, ²²⁶Ra, ²³²Th, and ²³⁸U) were evaluated for the first time on volcanic ash soils of the Argentine Patagonian Andes. The study was carried out along a topoedaphoclimatic gradient, encompassing soils from Xeric Mollisols to Udic Andisols, and different land uses. Median mass-specific activities of the lithogenic radionuclides ⁴⁰K, ²¹⁰Pb, ²²⁶Ra, ²³²Th, and ²³⁸U were 375, 8, 17, 19, and 29 (Bq kg⁻¹), respectively, all falling within global natural background levels, yet distinct spatial and vertical patterns emerged. Radionuclide activities increased with sand content and decreased with organic matter, highlighting the role of the parent material and texture. In dry-site Mollisols, ⁴⁰K and ²¹⁰Pb increased with depth, while in humid-site Udands, activities declined with depth, suggesting leaching and surface accumulation by allophane–organic matter complexes. The 238U/226Ra activity ratio showed disequilibrium, indicating young, developing soil profiles. In Xerolls, where native forest was replaced by afforestation and rangeland use, erosion-driven degradation was evident. The distribution of radionuclides along the slopes was closely linked to the topographic position and slope gradient. These results underscore the sensitivity of radionuclide patterns to parent material, soil-forming processes and land use and provide a valuable reference for environmental monitoring in volcanic landscapes. Full article

Forest fires alter multiple soil properties, from those related to the carbon cycle to mineralogy; however, the responses of various soils to thermal impact remain unclear. This study examined the impact of fire-induced heating (300, 600, and 900 °C) on the properties of two contrasted soils (Andisol and Inceptisol) with regard to soil organic carbon (SOC), total organic carbon (TOC), dissolved organic carbon (DOC), recalcitrant organic carbon (ROC), soil pH, electrical conductivity (EC), soil water repellency (SWR), soil aggregate stability (SAS), and mineralogy using X-ray diffraction (XRD). SOC and TOC decreased as temperatures increased, with a more pronounced decrease in Andisol (90% loss) than in Inceptisol (80% loss). DOC and SWR peaked at 300 °C but disappeared above 600 °C. Further, ROC increased at 300 °C in both soils, but behaved differently at higher temperatures, remaining stable in Inceptisol and being eliminated in Andisol. Soil pH increased at 600 and 900 °C; meanwhile, EC increased progressively in Andisol but peaked at 300 °C in Inceptisol. SAS remained high in both soils (between 85 and 95%) despite heating. The mineralogical analysis demonstrated how heating induced transformations in iron minerals into more oxidized forms (as hematite and maghemite) in the Andisol, while clay minerals and gibbsite decreased feldspar and quartz accumulation promotion in the Inceptisol. In summary, the initial properties of each soil influenced their respective responses to fire. Full article

This study evaluated the adsorption and desorption of imidacloprid (IMI), thiamethoxam (THM) and clothianidin (CLO) in an andisol (Freire soil) and an inceptisol (Chufquén soil) from southern Chile with different organic matter and clay contents. The soils had a slightly acidic pH and clay and clay-loam textures. The tests were carried out at 20 °C with CaCl₂ 0.01 M as the electrolyte. Kinetic experiments were performed and isotherms were fitted to the pseudo-second-order, Elovich, Weber–Morris, Freundlich and Langmuir models. The kinetics were best described by the pseudo-second-order model (R² > 0.99), indicating chemisorption; the rate was the highest for THM, although IMI and CLO achieved the highest retention capacities. The Chufquén samples, with lower organic matter but 52% clay, exhibited the highest K_f and q_m of up to 12.4 and 270 mg kg⁻¹, respectively, while the K_d (2.3–6.9 L kg⁻¹) and K_oc (24–167 L kg⁻¹) coefficients revealed a moderate leaching risk. THM was the most mobile compound due to its high solubility. Desorption was partially irreversible (H = 0.48–1.48), indicating persistence in soil. FTIR analysis confirmed the interaction with O-Al-O/O-O-Si-O groups without alterations in the mineral structure. In the soils examined in this study, the clay fraction and variable-charge minerals, rather than organic matter, were more closely associated with the adsorption behaviour of these NNIs. Full article

Heavy metal contamination in agricultural soils threatens food security and public health, especially in volcanic regions where ash alters soil properties. This study evaluates the effects of soil amendments on physicochemical properties, nutrient availability, and heavy metal accumulation in ash-affected (Mocha) and non-affected (Puyo) soils in Ecuador. A field experiment tested compost, poultry manure, inorganic fertilizer, and a control on onion (Allium fistulosum) and parsley (Petroselinum crispum). Soil analyses assessed the bulk density, texture, pH, electrical conductivity, organic matter, nutrients, metals, and metalloid concentrations of the soils and crops. Mocha soils exhibited volcanic Andisol characteristics, while Puyo soils resembled eastern Ecuadorian soils, both showing high nitrogen but deficiencies in phosphorus, potassium, and calcium. Arsenic (As), lead (Pb), and chromium (Cr) levels in soils varied between regions but not among treatments. In Mocha, As bioavailability decreased with poultry manure and compost, while other metals remained stable except in fertilized soils. In Puyo, organic amendments reduced Hg, Pb, Ni, and Cr but increased them in fertilized soils. All treatments met Ecuadorian limits for As, Cd, Pb, and Ni but exceeded those for Hg and Cr. Organic amendments improved soil quality, reduced metal mobility, and supported sustainable agriculture, with Mocha soils appearing more suitable for cultivation. Full article

Intensive agricultural management affects the physical, chemical, and biological properties of soil, potentially contributing to a decrease in soil carbon storage. In this study, the effects of soil management intensity on soil organic carbon (SOC) content and its labile fractions, i.e., water-soluble organic carbon (OC-sol) and permanganate oxidizable carbon (POXC), were evaluated in a volcanic-ash-derived soil (Andisol) with a very high soil organic matter (SOM) content (>20%). These indicators were associated with water-stable aggregates (WSAs) and biological indicators, namely, earthworm density, cellulase activity, and autoclaved-citrate-extractable (ACE) proteins, related to the decomposition of SOM and its physical protection. The conditions evaluated were secondary native forest (SF), naturalized grassland (NG), no-till (NT), and conventional tillage (CT), considering the last item to be representative of a higher agriculture management intensity. Soil samples were collected by horizon. The SF and NG soil showed higher contents of SOC, OC-sol, and POXC. When comparing the evaluated annual cropping systems, NT showed higher values than CT (p < 0.05) in the first horizon (Hz1), while similar values were found at deeper horizons. The highest cellulase activity, ACE protein levels, and earthworm densities were found in NG and SF. NT also showed significantly higher levels of the aforementioned factors than CT (p < 0.05). A positive and significant relationship was found between the SOC content and WSA (R² = 0.76; p < 0.05) in the whole profile and between POXC and WSA for Hz1 (R² = 0.67; p < 0.05). Soil C storage was affected by the intensity of agricultural management, mainly because of the effect of tillage on structural stability, considering that biological activity synthesizes compounds such as enzymes and proteins that react and adhere to the mineral fraction affecting aggregate stability. The C content stored in the soil is consequently a key indicator with which to regulate SOM and protect SOC. Full article

While soil responses to organic and inorganic phosphorus (P) fertilizers have been widely studied, plant physiological and molecular responses remain insufficiently characterized. Such an understanding is necessary to develop sustainable P fertilization strategies that enhance plant performance in soils with P limitations. This study investigated the impact of poultry manure (PM) and its combination with phytase enzyme on molecular plant responses involved in P use efficiency (PUE) of ryegrass plants growing on a P-deficient Andisol. A greenhouse experiment under controlled conditions was performed to evaluate soil properties, plant biomass, P uptake, plant performance, and the expression of P transporters under the following P treatments: P deficiency (PD), mineral fertilizers (F), PM alone, and PM combined with phytase. The combination of PM and phytase enhanced soil P availability by 60% and increased soil P enzyme activities 2.6-fold, facilitating the mineralization of organic P. This resulted in a 63% increase in shoot P concentration and a 35% enhancement in shoot biomass. Additionally, oxidative stress markers decreased, with lipid peroxidation in roots reduced up to five-fold, while antioxidant activity increased 1.6-fold. Molecular analysis revealed that the expression of the P transporter gene LpPHT1;4 was upregulated 9.3-fold, indicating an improved capacity for P acquisition and utilization. These findings suggest that phytase-mediated hydrolysis of organic P and the activation of plant P transporters are key mechanisms driving enhanced P uptake and efficiency in P-deficient soils. Full article

The widespread presence of microplastics (MPs) in agricultural soils raises concerns regarding their impact on crop health and productivity, particularly in legumes, which are known to have soil-enhancing properties. This study investigated the effects of low-density polyethylene (LDPE), polypropylene (PP), and polyamide (PA) MPs on white lupine (Lupinus albus L.). Plants were cultivated for 110 days in glass pots containing 700 g of volcanic soil mixed with 2% w/w MPs, with four treatments (control, LDPE, PP, and PA) and five replicates each. The results indicated that PP increased soil ammonium and available nitrogen by 71% and 60%, respectively, compared to the control. LDPE increased root length by 3% and decreased chlorophyll content by 2.7%, whereas PA increased chlorophyll levels by 3.5%. Oxidative stress markers were significantly elevated in the LDPE and PA treatments, with 12% and 5.4% increases, respectively, compared with the control. However, no significant differences were observed in enzyme activity or basal soil respiration. These findings contribute to the understanding of how short-term exposure to MPs affects agricultural soils and emphasize the necessity for long-term studies to elucidate their potential effects. Full article

Water quality is a fundamental aspect of public health and environmental sustainability. In rural areas, the physicochemical and microbiological quality of drinking water depends not only on hydrogeological conditions but also on anthropogenic activities carried out on the surface of the basin. This study aimed to identify natural and anthropogenic influences related to the quality of drinking water in rural areas of southern Chile. In order to perform this, six rural drinking water systems were evaluated. A total of two types of catchment sources (groundwater and surface water) that were located in a longitudinal gradient were used, where coverage and sequences of rocks and soils could be differentiated. The results show that the water delivered by the majority of rural drinking water systems studied was of good quality, meeting the standards of Chilean and international regulations. No fecal coliforms or Escherichia coli were recorded. In addition, we recorded that turbidity, color, pH, concentration of total dissolved solids and fecal coliforms showed significant differences between groundwater and surface water. We also recorded that in two groundwater systems, iron and manganese levels slightly exceeded the regulations, endangering the acceptability of the water. These increases can be related to the natural origins of the metals, linked to the presence of oxides in Andisol- and Utisol-type volcanic soils. Full article

The application of urea as a nitrogen fertilizer and herbicide is a common practice in agricultural systems. However, there is no background information on how the soil acidification caused by urea might affect the herbicide bioavailability in volcanic soils. The persistence study was conducted under microcosm incubation conditions in two Andisol soils amended with a field equivalent nitrogen dose of 200 kg N ha⁻¹ and double dose of 400 kg N ha⁻¹. Clopyralid, fluroxypyr, picloram, and triclopyr, acidic ionizable herbicides, were applied at the field equivalent dose. Adsorption studies were also carried out on both soils at pH 4, 5, and 6. Clopyralid and picloram showed the greatest increase in half-life in the range of 20–80%. The application of twice the dose of urea resulted in minor changes. A higher adsorption implies a higher persistence of the herbicides. This was more evident for the Piedras Negras soil (PNS). The conclusion of this work is that soil acidification by urea increases the persistence of ionizable herbicides in Andisol soils and that this effect depends on the acidity of the herbicide and the physico-chemical characteristics of the soil, which are among the most determining factors. Full article

Reusing the by-products from wood pulp processing can promote the efficient use of resources. In this sense, the objective of this research was to determine the agronomic efficiency of CaCO₃ and Na₂SO₄ by-products from wood pulp processing to establish criteria for their use and avoid undesirable side effects when applying these materials to the soil. Six treatments in proportions of 1; 0.9; 0.75; 0.5, 0.25, and 0, of CaCO₃/Na₂SO₄, respectively, were incubated at a constant temperature and humidity for 15 days. The first proportion consisted of 100% CaCO₃, while M1 mixed 90% CaCO₃ and 10% Na₂SO₄, M2: 75% CaCO₃ and 25% Na₂SO₄, M3: 50% CaCO₃ and 50% Na₂SO₄, M4: 25% CaCO₃ and 75% Na₂SO₄, with the last proportion comprised of 100% Na₂SO₄. Samples of 40 g from two soil series, Licantén (Inceptisol) and San José (Andisol), were used. The rates applied for each treatment were 0, 1, 2, 4, and 8 g of material per kg of dry soil. At the end of the incubation period, pH in water, pH in CaCl₂, exchange bases (Ca²⁺, Mg²⁺, K⁺ and Na⁺) and extractable sulfur were determined. The results showed that the San José soil had a pH buffering capacity three times higher than that of the Licantén soil. The linear increase in pH was thus explained by the soil type in relation to the applied rate of CaCO₃. The analysis of the increase in the exchangeable Na percentage (ESP) showed that the soils increased up to about 70% of their ESP with the highest added rate of Na₂SO₄. The application of a mixture of 25% Na₂SO₄ and 75% CaCO₃ resulted in an increase in the ESP close to 15%; therefore, it is not recommended to use mixtures with a Na₂SO₄ content higher than 25% in these soils. Finally, we affirm that for M2 the maximum recommended dose for application should be 4 Mg ha⁻¹, i.e., 3 g of material per kg of soil. Full article

Agricultural soils account for about 60% of the global atmospheric emissions of the potent greenhouse gas nitrous oxide (N₂O). One of the main processes producing N₂O is denitrification, which occurs under oxygen-limiting conditions when carbon is readily available. On grazed pastures, urine patches create ideal conditions for denitrification, especially in soils with high organic matter content, like Andisols. This lab study looks at the effects of Urine-urea-N load on the Andisol potential to emit N₂O. For this, we investigated the effects of three levels of urea-N concentrations in cow urine on emissions of N₂O, N₂, and CO₂ under controlled conditions optimised for denitrification to occur. Results show total N₂O emissions increased with increasing urine-N concentration and indicate that denitrification was the main N₂O-producing process during the first 2–3 days after urine application, though it was most likely soil native N rather than urine-N being utilised at this stage. An increase in soil nitrate indicates that a second peak of N₂O emissions was most likely due to the nitrification of ammonium hydrolysed from the added urine, showing that nitrification and denitrification have the potential to play a big part in N losses and greenhouse gas production from these soils. Full article

The use of organic waste in agricultural soil can enhance crop yields, improve waste management, and boost soil carbon (C) sequestration. However, more field data are required to fully understand the impacts of pyrolyzed and unpyrolyzed animal manures. The objectives of this study were (i) to analyze the impact of two pyrolyzed and unpyrolyzed manures on soil properties, soil C storage, and clover productivity and (ii) to examine the biochar’s movement through the soil profile. Poultry litter (PL), dairy manure (DM), poultry litter biochar (PLBC), and dairy manure biochar (DBC) were applied at rates of 8 t ha⁻¹ in a field experiment with red clover (Trifolium pratense L. var. Quiñequeli) in an Andisol. We monitored changes in soil chemical properties, foliar properties, and crop yield after three clover cuttings. To examine the movement of biochars through the soil profile, we set up a lab experiment where field conditions were simulated. PLBC, DBC, and PL increased soil pH by 0.5 (6.44), 0.28 (6.22), and 0.25 (6.19) units, respectively. Soil available P increased in both pyrolyzed and unpyrolyzed PL treatments (by 8.53 mg P kg⁻¹, on average). Clover yields only increased in treatments with amendments that provided more available P and increased the pH. The addition of DBC increased soil total C (30.3%). Both biochars added to the soil surface exhibited little movement through the soil profile (2 to 4 cm). In this study, the pyrolysis of manures emerged as an option for reducing waste volume from the farming industry. Manure biochars proved useful at low rates for enhancing crop yields (PLBC) and storing C in the soil (DBC). Full article

Background: There are few reports of crop rotations with high residue incorporation in terms of their effects on indicator crop yields and soil properties, so this study evaluated the effect of two medium-term biannual rotations on wheat yield development and soil chemical properties after six years of rotation. Methods: The experiment was conducted with two biannual rotations (canola–wheat and bean–wheat) and four residue incorporation levels (0%, 50%, 100%, and 200%) in an Andisol in south central Chile. Wheat grain yield and residue production were evaluated during each biannual cycle during three cycles of crop rotation, and soil chemical properties were evaluated at final evaluation. Results: The use of beans as a wheat preculture partially improved grain yield in 7.3%. The chemical properties of the soil showed an increase in pH (0.08 units), organic matter content (15 g kg⁻¹), and concentrations of P (2.8 mg kg⁻¹), S (7.4 mg kg⁻¹), and Al (0.03 cmol₊ kg⁻¹) after canola cultivation, while after bean cultivation there was an increase in the available N concentration (3.7 mg kg⁻¹). The use of increasing doses of residue allowed for an increase in the soil pH and decrease in the exchangeable Al concentration. Conclusion: The continuous incorporation of the residues produced within the biannual rotations evaluated in this volcanic soil did contribute to improving some chemical properties of the soil without affecting wheat crop yield. Full article