Search Results (2,243)

To investigate the effects of co-application of KMnO₄-modified biochar and organic fertilizer on the physicochemical properties, carbon and nitrogen content, and growth of Chinese cabbage in acidic red soil. Using typical acidic red soil from Yunnan as the test substrate, this study conducted a pot experiment with four treatment groups: control (CK), organic fertilizer alone (OF), biochar combined with organic fertilizer (BOF), and potassium permanganate KMnO₄-modified biochar combined with organic fertilizer (Mn-BOF), each at three application rates (1500, 3000, and 4500 kg/ha). The results indicated that KMnO₄ modification significantly improved the pore structure of biochar, increasing its specific surface area by 22.776%, and successfully loaded manganese onto the biochar surface. Compared with the CK, all treatments significantly increased soil pH, organic matter (SOM), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), and available potassium (AK), with the effects gradually increasing as the application rate rose; the 4500 kg/ha treatment yielded the best results. The Mn-BOF treatment was most effective in increasing soil organic carbon (SOC), total nitrogen (TN), soluble organic carbon and nitrogen (DOC/DON), and microbial carbon and nitrogen (MBC/MBN); simultaneously, the Mn-BOF treatment significantly promoted the growth of Chinese cabbage, with yield under the 4500 kg/ha treatment increasing by 158.58% compared to CK (under pot-grown conditions), and soluble total sugars, chlorophyll, and vitamin C content also significantly increased. In summary, Mn-BOF can improve the fertility of acidic red soil, particularly demonstrating excellent performance in enhancing key carbon and nitrogen components such as SOC, TN, DOC, DON, MBC and MBN. This, in turn, promotes increased yield and improved quality of Chinese cabbage, providing feasible guidance for enhancing soil fertility in highland agricultural systems. Full article

Soil salinization poses a significant global challenge to agriculture and the environment, leading to decreased soil fertility and hindered crop growth. Therefore, the development of effective and environmentally friendly soil improvement strategies is crucial for sustainable agriculture. In this study, a range of eco-friendly, versatile, and highly absorbent hydrogels for soil enhancement were created using itaconic acid (IA) as a hydrophilic monomer. Furthermore, their effectiveness and application in agriculture were thoroughly evaluated. The nano-iron-loaded IA-based hydrogels (nano-iron (III) oxide (nano-Fe₂O₃)/Poly itaconic acid (PIA)-Acrylamide (AM)/Sodium alginate (SA)) hydrogels demonstrated exceptional water absorption and retention capabilities. They exhibited remarkable soil conditioning properties by leveraging carboxyl groups for electrostatic adsorption of saline ions and the porous structure created by the crosslinked network. These features not only significantly facilitated gradual regulation of pH levels and salinity but also effectively enhanced organic matter in saline–alkali soil. Meanwhile, nano-Fe₂O₃ simultaneously served to stabilize the hydrogel structure and enhance crop nutrient absorption. Wheat cultivation trials demonstrated that the hydrogels notably enhanced the growth of 7-day-old wheat seedlings. The degradation rates of the hydrogels can be adjusted by varying the IA amount, allowing for the continuous release of small organic molecules to enhance soil quality, aligning with various crop growth cycles. Overall, these hydrogels function as environmentally friendly and versatile soil conditioners, offering significant potential for enhancing agricultural soil quality and expanding into related fields. Full article

Sustainable management of permanent grasslands requires evidence-based selection of fertilization practices that support long-term soil organic matter quality and ecosystem function. This study addresses the need to identify optimal agricultural practices in permanent grasslands and the effects of organic and inorganic fertilizers on soil humic substances (HS) composition and stability. Grassland plots were amended after cutting with mineral fertilizer (NPK), farmyard manure (FYM), cattle slurry (CS), or digestate (DIG), and humic acids (HA) were isolated using the standard International Humic Substances Society procedure. The elemental composition, total carbon and nitrogen contents, C/N ratio, and selected biogenic elements were determined using routine laboratory methods, while infrared spectroscopy, fluorescence excitation–emission matrix analysis, and electron paramagnetic resonance spectroscopy were applied to characterize chemical structure and semiquinone radical concentrations. Principal component analysis (PCA) indicated distinct clustering of fertilization treatments, which was supported by a statistically significant effect (p < 0.05) based on ANOVA. The results suggest that the fertilization regime was associated with variation in HS composition and radical abundance. DIG and NPK treatments showed lower O/C ratios and radical concentrations, potentially reflecting more reduced humic acids. In contrast, FYM and CS treatments tended to exhibit higher radical concentrations and O/C ratios. These findings highlight the importance of fertilizer type in shaping soil organic matter dynamics in managed grassland ecosystems and provide a scientific basis for the development of sustainable soil management strategies and environmentally sound fertilization practices in permanent grassland systems. Full article

Organic citrus production in semi-arid Mediterranean regions is increasingly challenged by water scarcity, soil degradation, and rising phytosanitary pressure associated with climate change. This study evaluated different sustainable management strategies under commercial organic citrus production conditions in the Andarax Valley (Almería, southeastern Spain). Two complementary field trials were conducted: (i) the assessment of four weed management systems—shallow tillage, mechanical mowing, sown cover crop, and partial manual mowing—and (ii) the comparison of four mass-trapping systems for the control of Ceratitis capitata. Fruit quality parameters, yield performance, and trapping efficacy were evaluated under commercial organic farming conditions. Weed management treatments did not significantly affect internal fruit quality parameters, including juice content, total soluble solids, titratable acidity, and maturity index, which were mainly determined by cultivar-related factors. In contrast, yield showed significant responses to treatment, growing season, and cultivar. The sown cover crop treatment (T3) produced the highest mean yields in both growing seasons, reaching 56.6 and 72.9 kg tree⁻¹ in seasons 1 and 2, respectively. In the mass-trapping trial, the liquid trap baited with hydrolyzed protein (R-9) showed the highest capture efficacy (0.060 flies trap⁻¹ day⁻¹), significantly outperforming the control treatment (0.014 flies trap⁻¹ day⁻¹) and the other evaluated trapping systems. Conversely, dry trap models (A-9 and V-8) recorded significantly lower capture rates (FTD < 0.01), which may be associated with lower retention efficiencies documented in the literature for dry-killing designs. All treatments exhibited high female selectivity (>94%). In addition, a pronounced edge effect was detected, with significantly higher captures concentrated along the orchard perimeter. Overall, the results support the integration of functional cover crops and perimeter mass-trapping strategies as sustainable tools to improve resilience and pest management in Mediterranean organic citrus production systems. Full article

Biochar can enhance microbial-mediated organic phosphorus mineralization, but the underlying mechanisms remain unknown in forest soils with varying pH values. An incubation experiment was conducted using karst (alkaline) and non-karst (acidic) forest soils. Four amounts of bagasse biochar were applied (0, 5, 10, and 15 t·hm⁻²) to assess their effects on soil phosphorus availability and microbial community structure. Olsen-P content of alkaline and acidic forest soils increased with increasing bagasse biochar addition and incubation time, especially in non-karst forest soil. The structure and diversity of phoD-harboring bacterial community of acidic forest soil were significantly altered by the amount of bagasse biochar added and the incubation time, whereas those in alkaline karst forest soil were not significantly affected. The relative abundance of the dominant order Burkholderiales reached (43%) in acidic forest soil, significantly exceeding the (9%) recorded in alkaline karst forest soil. The phoD bacteria in acidic forest soil had more complex microbial networks and were more closely related to phosphorus fractions than those in alkaline forest soil. Structural equation modeling indicated that soil phosphorus availability was directly controlled by bagasse biochar input in acidic forest soil, with an indirect pathway linked to phoD bacterial community structure. The contribution of phoD bacteria to the variation in phosphorus availability was higher in acidic forest soil than in alkaline forest soil based on variance partitioning, indicating that enhancing soil phosphorus availability with bagasse biochar depends on the amount added, soil type, and its regulation of phoD bacterial communities. Full article

Acid mine drainage (AMD) is enriched with arsenite (As(III)), arsenate (As(V)), and jarosite. While jarosite can immobilize arsenic (As) through adsorption and other mechanisms, it dissolves and transforms into other minerals under near-neutral and reducing conditions via microbial mediation, thereby altering As fate. Fulvic acid (FA), a ubiquitous natural organic matter in the environment, has been proven to exhibit complex interactions with various iron minerals, Fe/S-metabolizing microorganisms, and As. However, the role of FA in the bioreduction and transformation of jarosite, as well as its subsequent impact on As mobility and fate, remains unclear. This study aims to elucidate the regulatory effect of FA on the biodissolution and transformation of jarosite, and the corresponding changes in As speciation. The results showed that FA exerted contrasting effects depending on arsenic speciation. In the As(III) treatments, FA intensified the inhibition of microbial dissimilatory sulfate reduction, suppressed sulfide production, and consequently limited orpiment formation. In contrast, in the As(V) treatments, FA enhanced the association of As(V) with jarosite surfaces, reduced aqueous As stress, and supported the persistence of As-tolerant sulfate-reducing populations. This promoted jarosite transformation toward mackinawite and facilitated As immobilization through orpiment precipitation. This study reveals the critical role of FA in the migration and transformation of As in mining areas, providing novel insights for optimizing AMD remediation strategies such as soil capping. Full article

This study investigated the epidemiology and incidence of citrus Huanglongbing (HLB) disease in citron (Citrus medica L.) under varying field conditions. This research specifically aimed to quantify disease severity, assess populations of the primary vector, the Asian citrus psyllid (Diaphorina citri), and identify potential alternative host plants sustaining the vector and the pathogen. Field surveys were executed across three sites characterised by distinct elevations and management practices. Site-level soil nutrient profiles exhibited moderate acidity (pH 4.67–5.74) and significant differences in organic matter and nitrogen. These findings suggest that localised deficiencies in calcium and boron may exacerbate disease severity, contributing to the varied epidemiological patterns observed across sites. Analysis revealed that both HLB disease severity and D. citri population density were significantly influenced by altitude, field condition, and orchard management. The low-elevation site (860 m above sea level (ASL)), characterised by poor maintenance, exhibited the highest mean psyllid populations (averaging 13 individuals per sticky trap per day) and the most severe disease symptoms. Conversely, the high-elevation site (1674 m ASL) displayed significantly lower infection rates and healthier tree conditions. Symptomatic citron trees across all sites consistently exhibited characteristic HLB foliar and fruit symptoms (blotchy mottle and lopsided fruits). Quantitative Polymerase Chain Reaction (qPCR) successfully detected the causal agent, Candidatus Liberibacter asiaticus (CLas), in symptomatic citron samples from all locations, with the highest relative fold-change (2^−ΔΔCt = 4628.24). Crucially, multiple developmental stages of D. citri were observed infesting the common weed Bidens pilosa. Furthermore, qPCR confirmed the presence of CLas DNA within the B. pilosa tissue itself (2^−ΔΔCt = 210.84). This finding constitutes the first field-based evidence that B. pilosa can serve as a novel alternative host that supports both the D. citri vector and the CLas pathogen. These results establish citron as a highly susceptible host and identify B. pilosa as a new, critical epidemiological link in the HLB transmission cycle, thereby underscoring the necessity for integrated, landscape-level disease management strategies. Full article

Single-use plastic residues persist in agricultural and peri-urban soils of the Ecuadorian Andes. Regionally sourced starch-based films are a plausible local replacement for short-lifetime petroleum plastics, yet field-relevant degradation data for tropical high-altitude soils remain scarce. This study evaluated the soil biodegradability of bioplastic films produced from Colocasia esculenta (malanga blanca) and Manihot esculenta (yuca) across three contrasting soils from Chimborazo, Ecuador (ESPOCH, San Andrés and Río Chimborazo; 2825–3249 m a.s.l.) as a function of their physicochemical properties and bibliographically inferred microbial context. The films were prepared by citric acid starch extraction, glycerol plasticization and carboxymethylcellulose reinforcement; the gravimetric weight loss was tracked on days 0, 11, 18, 27, 40 and 47 on n = 20–21 film replicates per soil × feedstock combination, with the soils characterized by their pH, electrical conductivity and organic matter. After 47 days, the malanga films reached 42.3 ± 13.6%, 22.9 ± 10.7% and 54.1 ± 19.3% mean (±standard deviation, SD) weight loss in the ESPOCH, San Andrés and Río Chimborazo soils, respectively; the yuca films reached 24.4 ± 6.5%, 21.1 ± 6.8% and 49.4 ± 18.7%. The between-soil differences were statistically significant at 47 days according to the analysis of variance (ANOVA) (malanga: F = 22.17, p < 0.001; yuca: F = 34.08, p < 0.001; Tukey’s Honestly Significant Difference (HSD)), with the results corroborated by the Kruskal–Wallis method (H = 29.16 and 37.05; both p < 0.001), given the partial departure from normality identified by the Shapiro–Wilk test. The ordering of degradation departed from the bulk organic matter ranking, indicating that microbial community composition, rather than organic matter quantity alone, was the proximal driver. These findings extend the scarce evidence base on cassava/taro film degradation under high-Andean conditions. Full article

The role of mangrove root exudates in mediating the nitrogen cycle, particularly under high dissolved inorganic nitrogen (DIN) input, in coastal ecosystems remains unclear. This research investigated variation in the root exudates, and nitrogen transformation and output, in constructed mangrove wetlands planted with Kandelia obovata under high, moderate, and low nitrogen-input levels (PCWs-H, PCWs-M, and PCWs-L, respectively). PCWs-H promoted increased root density and biomass accumulation, enhancing soil nitrogen sequestration, whereas PCWs-L induced greater specific root length, specific root surface area, and number of root tips. These changes directly influenced denitrification efficiency. Hydroxymethoxyphenylcarboxylic acid-O-sulfate and Arg-Ser released in root exudates under PCWs-H might act as potential denitrification inhibitors, thereby suppressing denitrifiers and impairing dissolved nitrogen purification. Elevated nitrogen loading predominantly limited denitrification, resulting in relative NO₃⁻-N removal rates of PCWs-H < PCWs-M < PCWs-L (p < 0.05). Compared with PCWs-H and PCWs-L, the enhanced soil organic nitrogen storage under PCWs-M was associated with flavonoids in root exudates. Metagenomic analysis showed that denitrification was the dominant nitrogen removal pathway. Nitrogen loading influenced the effects of root exudates on the microbial community. Under PCWs-H, triterpenoids promoted norBC and nirK/S abundance but depressed amoABC abundance. Sterols and flavonoids in exudates under PCWs-L depressed nosZ abundance, instead activating dissimilatory nitrate reduction to ammonium. Compared with PCWs-H and PCWs-L, N₂O emissions were minimal under PCWs-M. This study revealed that mangrove root exudates mediate the nitrogen cycle in mangrove wetlands, providing a theoretical basis for local authorities to manage DIN inputs and mitigate N₂O emissions. Full article

Soil biological activity integrates microbial processes involved in organic matter decomposition and nutrient cycling, yet its long-term response under agricultural systems in Paraguay remains poorly documented. This study evaluated soil biological activity in a 32-year field experiment in the Eastern Region of Paraguay, comparing cropping systems differing in tillage intensity and crop rotation diversification. Soil samples from the 0–20 cm layer were analyzed for microbial biomass carbon (MBC), β-glucosidase (BG), urease (URE), acid phosphatase (AP), arylsulfatase (ARS), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (P), sulfur (S), and pH. Our results revealed that BG, URE, and AP increased under no-tillage, particularly in the most diversified no-tillage rotation, with 71%, 90%, and 51% higher activities, respectively, than conventional tillage. MBC and ARS were not significantly affected by cropping systems. Principal component analysis, Spearman correlations, and Mantel analysis indicated that enzymatic responses were associated with SOC, TN, P, S, and pH, linking soil biological activity with chemical attributes related to nutrient cycling. These findings show that diversified no-tillage strengthens soil biological functioning under representative Paraguayan grain-production conditions, providing long-term local evidence to guide soil-health management, crop diversification strategies, and more sustainable agricultural systems in the region. Full article

The production of inexpensive, effective sorbents from natural materials for the purification of water bodies and/or soils is a pressing problem. Therefore, the purpose of this manuscript is to summarize current approaches to the use of brown coal (lignite) and its processing products (humic acids, HAs) as sorbents for the purification of aqueous and soil environments from heavy metal ions and other pollutants. Modification of lignite (chemical, biological, physicochemical) or the creation of lignite–mineral composites significantly increases its sorption capacity and stability: after modification, the sorption capacity can reach more than 85 mg of heavy metals per g of sorbent, which is only 3 times lower than that of specialized, expensive sorbents. Also, good results are achieved in the case of sorption of water-soluble organic drugs, dyes, etc. Humic acids obtained from brown coal have better selectivity and efficiency than the original lignite, and slightly worse than the modified one, in terms of removing cadmium, lead, copper, and other toxic elements; and also, can complex with organic xenobiotics. Current research trends indicate growing interest in multifunctional composite sorbents, environmentally friendly extraction technologies, and the development of materials with enhanced selectivity and regeneration ability. Future studies should focus on improving the understanding of sorption mechanisms, optimizing modification strategies, scaling up lignite-based technologies for practical environmental applications, and developing waste-free technologies to produce sorbents from lignite. Full article

Lameness in cattle is generally described as a condition characterized by an abnormal walking or posture which is often managed with copper sulfate (CuSO₄) hoofbaths, e.g., in case of digital dermatitis (DD). This review evaluates in vivo trials from the last 15 years (January 2010–March 2026) and the efficacy of CuSO₄ hoofbaths, their environmental impact, and the availability and performance of alternative products and agents (e.g., nanomaterials), with the aim of identifying sustainable management strategies for dairy farms and One Health goals. The selection criteria focused on peer-reviewed references and technical reports published in English. Hoofbath wastes can introduce high copper (Cu) loads into manure (500–2000 mg/L), leading to soil accumulation, impaired non-pathogenic microbial populations, and potential co-selection for pathogen resistance. Therefore, CuSO₄ can be effective but poses environmental risks due to Cu accumulation in soil and water, with mean concentrations reaching 5.7 ± 6.6 ppm Cu in areas where hoofbath effluent is discharged. Cu-free alternatives (e.g., quaternary ammonium compounds, organic acids) show comparable efficacy in some studies, but independent data on their environmental degradation and ecotoxicity are lacking. Although CuSO₄ hoofbaths pose environmental risks, they remain the most effective solution in improving hoof health. Controlled in vivo trials revealed that weekly 5% CuSO₄ hoofbaths can reduce the occurrence of lameness caused by hoof problems including DD by over 50%. Full article

Humus substances are an important part of stable soil organic matter, which is also influenced by the soil tillage system, particularly indirectly through the mechanisms of stabilisation. This study evaluated relationships within the humus substances–cations–soil texture system and differences between invasive and non-invasive tillage systems in four soils. The influence of exchangeable cations (K⁺, Na⁺, Ca²⁺, Mg²⁺, Fe³⁺, Al³⁺) and particle size distribution (sand, silt, clay) on quantity (humic and fulvic acids) and quality (ratio of HA/FA, degree of humification, colour coefficients) of humus substances was studied. In reduced tillage, the humus substances interacted mainly with iron and aluminium. Higher humus substance contents were associated with higher K⁺; the influence of Ca²⁺ was greater in coarse-grain soils (Haplic Chernozem, Eutric Regosol); and Al³⁺ was positively correlated with humic acids and negatively with fulvic acids. The statistical associations indicate that in conventional tillage, humus substances interacted mainly with Ca²⁺. Higher humic acid contents indicate an association pattern with higher Na⁺ contents; the relationship of Ca²⁺ appears more pronounced in fine-grained soils (Mollic Fluvisol, Haplic Luvisol); and Al³⁺ was positively correlated with fulvic acids and negatively with humic acids. The soil tillage system influenced the humus substances indirectly by a combination of factors—cation composition and soil texture in different ways. In reduced tillage, clay and silt were statistically associated with iron and aluminium; in conventional tillage, there were two branches: clay with divalent cations and silt with trivalent cations. The soil tillage system can modify the impact of carbonates on humus substances and thus indirectly change the character of transformation processes in the soil. Depth is very important in evaluating the influence of the soil tillage system. Full article

Soils are critical microbial habitats that support terrestrial ecosystem functioning and harbor numerous uncultured and functionally uncharacterized microbial groups. The black soil region in northeast China is a key agricultural ecosystem globally, yet the classification and functional understanding of its crucial microbial groups remain underexplored. In this study, we identified three high-completeness metagenome-assembled genomes (MAGs) from the Global Mollisols Genomic Atlas (GMGA). Phylogenetic and comparative genomic analyses identified these genomes as representing a novel evolutionary branch within the genus Flavobacterium, classified under the phylum Bacteroidota. Their novel taxonomic position is further supported by average nucleotide identity (ANI) and average amino acid identity (AAI) thresholds, demonstrating significant divergence from all known reference genomes. Functional annotation indicated that this species possesses strong plant polysaccharide degradation potential and a chemoheterotrophic lifestyle, together with environmental stress tolerance and a specialized nitrogen metabolic network adapted to agricultural inputs, thereby conferring a metabolic advantage in black soil environments characterized by high organic matter input and marked seasonal fluctuations. In addition, global distribution analysis showed that this lineage is widely distributed across diverse ecosystems and is significantly enriched in soil habitats, particularly in environments with fluctuating carbon sources and high organic matter inputs. The new species is most abundant in temperate soils, with the northeast black soil region of China emerging as a key hotspot. Based on these findings, and because no pure culture is currently available, we propose Candidatus Flavobacterium genomatis based on genome-resolved metagenomic evidence and in alignment with the International Code of Nomenclature of Prokaryotes rules for uncultivated prokaryotes. Our results expand the known species diversity of the genus Flavobacterium and suggest potential ecological roles of uncultured black-soil microbes in carbon and nitrogen cycling, including possible involvement in N₂O reduction under suitable environmental conditions. Full article

Malaysia plans to produce 80% of its rice requirement by 2030. To achieve the plan, new agronomic approaches have to be put in place to enhance the fertility of rice soils in the country. One of the options is to turn the infertile acid sulfate soils endemic in the low-lying coastal plains of Peninsular Malaysia into a new granary area. Using traditional agro-techs, rice yield in the area is below the national average of 4 t/ha/season. The low yield is due to soil acidity stress (pH < 4) together with Al³⁺ and/or Fe²⁺ toxicity. The critical pH for rice is 6, while the respective critical Al³⁺ and Fe²⁺ concentrations are 5.2 µM and 14.6 µM. The adverse conditions contributing to yield reduction can be resolved by applying appropriate soil amendments known to raise water pH, eliminating the toxic cations. The recommended agronomic practice is to apply ground magnesium limestone (GML) or ground basalt, or better still, apply GML or ground basalt in combination with bio-fertilizer, fortified with phosphate-solubilizing bacteria (PSB). The PSB increases water pH as well as helps rice plants secrete organic acids that reduce the toxic effects of Al³⁺ and Fe²⁺ via chelation. When pH rises >5, the toxic metals are precipitated, forming inert hydroxides. Ultimately, rice yield can be increased from 3 to 5 t/ha/season, which can last more than three consecutive cropping seasons. If this agro-tech is adopted throughout ASEAN, food security in the region will be sustained. Full article