Search Results (5,552)

Soils in alpine mining areas suffer from severe heavy metal contamination and infertility, yet little is known about the effects of different materials on soil improvement in such regions. In this study, a field experiment was conducted in farmlands contaminated by the Lanping lead–zinc mine in Yunnan, China, to compare the effects of four materials (biochar, organic fertilizer, lime, and sepiolite) on soil properties, heavy metal (lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) fractions and their availability, and the growth of Phaseolus coccineus L. Results showed that biochar and organic fertilizer significantly enhanced soil nutrient content and enzyme activities. Lime, biochar, and sepiolite effectively reduced heavy metal bioavailability by promoting their transition to residual fractions. Notably, biochar outperformed other materials by substantially increasing grain yield (by 82%), improving nutritional quality (sugars, protein, and starch contents raised by 20–88%), and reducing heavy metal accumulation in grains (by 36–50%). A comprehensive evaluation based on subordinate function values confirmed biochar as the most effective amendment. Structural equation modeling further revealed that biochar promoted plant growth and grain quality primarily by enhancing soil available nutrients and immobilizing heavy metals. These findings demonstrate the strong potential of biochar for remediating heavy metal-contaminated farmlands in alpine lead–zinc mining regions. Full article

Bioavailable phosphorus is essential for sustaining high crop productivity, yet excessive inorganic P fertilization often leads to P accumulation in stable soil forms, reducing utilization efficiency. Straw serves as an organic P source and enhances P availability by stimulating microbial activity. However, systematic studies on how organic P inputs (straw returning) and inorganic P fertilizers regulate soil bioavailable P through microbial and enzymatic processes remain limited. A 16-year field experiment was carried out in a rice–wheat rotation system, including five fertilization treatments: no fertilization (CK), optimized fertilization (OPT), increased N (OPTN), increased P (OPTP), and optimized fertilization combined with straw mulching/returning (OPTM). This study evaluates the impacts of long-term organic and inorganic P sources on soil P fractions, extracellular enzyme activities, and the composition of microbial communities, alongside their collective contributions to crop yield. In this study, based on soil samples collected in 2023, we found that fertilization led to significant increases in Citrate-P and HCl-P, enhanced the activities of β-1,4-glucosidase (BG), β-D-cellobiosidase (CBH), and β-1,4-N-acetylglucosaminidase (NAG), and altered both microbial diversity and co-occurrence network complexity. The OPTM treatment showed the highest yield and improved microbial diversity and network complexity, with Enzyme-P, Citrate-P, and HCl-P increasing by 62.64%, 11.24%, and 9.49%, and BG, CBH, and NAG activities rising by 22.74%, 40.90%, and 18.09% compared to OPT. Mantel tests and random forest analyses revealed significant associations between microbial community and biochemical properties, while partial least squares path modeling (PLS-PM) indicated that inorganic P source enhanced yield primarily through altering soil P dynamics and enzymatic processes, while microbial communities under organic P source acted as key mediators to increase crop productivity. These findings deepen insights into how microbial communities and enzymatic stoichiometry synergistically regulate phosphorus bioavailability and wheat yield, providing a theoretical basis for sustainable fertilization practices in rice–wheat rotation systems. Full article

The sustainable management of urban grasslands is crucial for resilient city ecosystems. With increasing urbanization, improving soil quality to support turfgrass growth has become a priority. This study evaluates biochar produced from Paulownia leaves (PLB), a low-cost byproduct of Paulownia cultivation, as a growing medium amendment. Raw leaves (PL) and PLB were characterized by SEM, FTIR, and elemental analysis to assess physicochemical changes. A three-month pot experiment under outdoor conditions was conducted with turfgrass plots exposed to different irrigation and fertilization regimes. Growing medium pH, moisture, electrical conductivity, cation exchange capacity, nutrient availability, grass chlorophyll content, and uptake were monitored. The application of PLB improved the growing medium structure, raised the pH by up to one unit, and enhanced pigment accumulation in turfgrass samples. When combined with nitrogen fertilizer, PLB significantly increased turfgrass visual quality, whereas under limited irrigation, PLB alone improved seedling establishment compared to controls. Statistical analysis confirmed significant treatment effects by ANOVA, and PCA provided a precise classification of treatment groups. These findings indicate that PLB can improve nutrient efficiency, turfgrass resilience, and organic waste management. Full article

In this study, aiming to determine the potential pollution risks to the soil foundation caused by permeable pavement after its operation, a fully permeable asphalt pavement system is constructed. Through an accelerated simulation of a three-year cumulative rainfall test, the cumulative characteristics of pollutants in the soil foundation of the permeable asphalt pavement were studied, and a risk assessment of heavy metal pollution was carried out. The results show that N and P pollution is relatively serious. TN and NH₄⁺-N decrease with the increase of the soil foundation depth (0–50 cm), and there is an obvious surface accumulation phenomenon. The average contents at a depth of 0–10 cm are 1219 mg/kg and 443 mg/kg, respectively. The content of TP first shows a decreasing trend and then an increasing one, and it faces the risks of surface accumulation and leaching loss in the middle and lower parts. Although the average contents of Cu, Pb and Zn at different depths all meet the requirements of the Soil Environmental Quality Standard (for agricultural land), they are all higher than the background values of soil elements in Jiangsu Province. Among them, Cu and Zn pose a considerable ecological risk to the environment, especially with serious enrichment in the surface layer. The above cumulative characteristics of pollutants in the fully permeable asphalt pavement provide reference value for extending the service life of the permeable pavement system. Full article

The use of high biomass production plants in studies of metal phytoremediation is an established practice. This strategy aims to identify plants that tolerate unusual amounts of metals such as nickel (Ni). When we compare the biomass production capacity of a Ni hyperaccumulator, for example Alyssum bertolonii, this rate is 4 to 5 kg/ha per crop cycle; on the other hand, species with a high biomass production capacity, for example Canavalia ensiformis, can produce 20 t ha⁻¹ to 25 t ha⁻¹ of green phytomass, 5 t ha⁻¹ to 8 t ha⁻¹ of dry phytomass and 1000 kg ha⁻¹ to 1800 kg ha⁻¹ of seeds. In this context, we planned an experiment to verify the tolerance and Ni accumulation capacity in Canavalia ensiformis. Our hypothesis was that increasing Ni concentration in the soil would not hinder the plant’s biomass production. We conducted a completely randomized experiment with five concentrations of Ni added to the soil and five replicates in a greenhouse during the vegetative stage. We evaluated the plant’s development, biomass production, and Ni accumulation in its organs. Our results demonstrated high tolerance to the metal, maintaining a biomass accumulation capacity of 68% of the dry mass in the soil with 277.8 mg kg⁻¹ of Ni at the highest concentration tested, compared to plants in the control soil. Considering that under these conditions the plants obtained a biomass of 10 g of leaves and 15 g of roots, and a nickel accumulation capacity of 75.05 mg kg⁻¹ in leaves and 102 mg kg⁻¹ in roots, the total Ni accumulation in the plants reached 2.37 mg Ni/plant in the soil with 277.8 mg kg⁻¹ of Ni. This soil Ni concentration would be lethal for most plants, and the metal concentration in the tissue exceeds the established limits for non-tolerant crops. With these results, this study aims to provide a foundation for improving the use of Canavalia ensiformis in phytoremediation. Full article

Heavy metals in farmland soils pose severe threats to agricultural productivity and food safety. To investigate contamination in the soil–wheat/corn system, 24 sets of adjacent farmland soil, wheat, and corn plant samples were collected near metal smelting facilities in Jinchang City, a typical urban oasis in northwestern China. Concentrations of Ni (nickel), Cu (copper), and Co (cobalt) were measured. Results indicated mean soil concentrations of 143.66 mg kg⁻¹ (Ni), 130.00 mg kg⁻¹ (Cu), and 24.04 mg kg⁻¹ (Co), all exceeding background values for Gansu Province, confirming that the sampling sites exhibit varying degrees of contamination with Ni, Cu, and Co. Correlation analyses revealed strong intermetal relationships (Ni, Cu, Co; p < 0.01), while spatial distribution patterns showed that Ni in wheat and corn grains closely mirrored soil Ni distribution. The bio-concentration factor (BCF) for wheat roots surpassed that of corn roots, highlighting wheat’s greater susceptibility to heavy metal uptake. Heavy metal levels in crop organs exceeded limits set by the Safety Guidelines for Feed Additives. Geo-accumulation indices and potential ecological risk assessments demonstrated substantial metal accumulation and varying ecological risks, with contamination levels ranked as Cu > Ni > Co. Non-carcinogenic hazard indices indicated elevated health risks for children consuming locally grown wheat and corn. This study provides a scientific foundation for crop rotation strategies and soil remediation in the region. Full article

In saline soil, legumes are restricted in their growth potential by osmotic stress, ion toxicity, and oxidative damage. We evaluated five halotolerant plant growth-promoting bacteria and selected Pseudomonas putida RT12 for its exceptional EPS production, tolerance to 600 mM NaCl, strong biofilm development, and plant growth-promoting traits (ACC-deaminase 2.86 µM·mg⁻¹; IAA 144 µM·mL⁻¹). RT12 was evaluated on two varieties of peas (peas2009 and 9800-10) with and without inoculation at 0, 75, and 150 mM NaCl concentrations. RT12 markedly protected growth under severe salinity: at 150 mM, shoot length rose to 23.13 cm (peas2009) and 17.44 cm (9800-10), in contrast to 11.18 cm and 12.32 cm in uninoculated specimens; root length and dry weight demonstrated comparable recovery (root length increased from 11.00 to 22.25 cm; dry weight of peas2009 from 0.15 to 0.17 and 0.41 to 0.71 g). RT12 sustained photosynthesis (total chlorophyll increased from 43.5 to 54.5), enhanced relative water content (to 94.1% and 97.2%), elevated osmolytes (total soluble proteins rose from 7.34 to 18.12 µg·g⁻¹ FW; total soluble sugars increased from 19.1 to 41.3 mg·g⁻¹ FW), and augmented antioxidant activities (catalase increased from 2.11 to 4.70; superoxide dismutase rose from 1.20 to 4.83; peroxidase increased from 0.08 to 0.18), while reducing malondialdehyde/hydrogen peroxide levels. RT12 was significant as it inhibited the accumulation of Na⁺ (from 23.95 to 16.32 mg·g⁻¹ DW), elevated K⁺ levels (from 17.76 to 29.12 mg·g⁻¹ DW), and restored the K⁺/Na⁺ ratio to normal (from 0.74 to 1.59) in inoculated plants compared to non-inoculated ones. A multivariate analysis linked growth protection to ionic homeostasis, osmotic control, and the detoxification of reactive oxygen species (ROS). RT12 is a promising bioinoculant for cultivating peas in saline-affected soils. Full article

Urban and peri-urban farmers in Malawi increasingly use treated and untreated wastewater for vegetable production, but little is known about the extent of heavy metal accumulation in both exotic and indigenous vegetables, particularly with respect to differences between edible tissues (leaves vs. stems). This study addresses this gap by measuring the concentrations of cadmium (Cd), chromium (Cr), lead (Pb), zinc (Zn), and copper (Cu) in wastewater, soils, and six vegetables including three exotic and three indigenous irrigated with effluent from the Soche Wastewater Treatment Plant in Blantyre. Metal concentrations were determined using Atomic Absorption Spectrophotometry. Wastewater contained Zn (0.01 ± 0.001 mg/L) and Cu (0.02 ± 0.018 mg/L), both below World Health Organization (WHO) and Malawi Bureau of Standards (MBS) limits (Zn: 0.2 mg/L; Cu: 2 mg/L), while Cd, Cr, and Pb were below detection limit. In soils, Zn reached 56.4 ± 0.5 mg/kg, exceeding the WHO limit of 36 mg/kg; other metals remained within WHO permissible values. Vegetables showed species- and tissue-specific variation in metal accumulation: Cr reached 4.65 mg/kg in Cucurbita moschata stems, Cd up to 0.31 mg/kg in Amaranthus retro-flexus leaves, and Pb up to 4.09 mg/kg in Brassica rapa stems—all above FAO/WHO permissible limits (2.3, 0.2, and 0.3 mg/kg, respectively). Duncan’s post hoc analysis confirmed significant differences (p < 0.05) across matrices and plant parts, with leaves generally accumulating more Zn and Cu than stems. Principal component analysis (PCA) revealed that Zn, Cu, Cr, and Pb in the wastewater-soil-vegetable system largely share a common source, likely wastewater effluent and historical soil contamination, while Cd showed a more sporadic distribution, highlighting differential accumulation pathways. Health risk assessments revealed high Health Risk Index (HRI) values, with Brassica rapa stems (HRI = 92.3) and Brassica rapa subsp. chinensis leaves (HRI = 82.2) exceeding the safe threshold (HRI > 1), indicating potential chronic risks. This study reveals potential health risks associated with wastewater irrigation due to heavy metal accumulation in edible vegetables, and therefore recommends further research on metal speciation, seasonal variation, and bioaccumulation at different crop growth stages. Full article

Coastal reclamation reshapes both soils and vegetation, yet their coupled trajectories remain poorly understood. Here we investigated soil–vegetation co-evolution across a 15-year chronosequence on Hengsha Island in the Yangtze River estuary. The reclaimed soils were formed primarily from dredged estuarine silt and clay slurry deposited during hydraulic filling. Four representative sites were studied, spanning 3 (Y3), 7 (Y7), 10 (Y10), and 15 (Y15) years since reclamation. Soil physicochemical properties (pH, electrical conductivity, salinity, nitrogen, phosphorus, potassium) were measured, while vegetation cover was quantified using NDVI and fractional vegetation cover (FVC) derived from satellite data. Soil conditions improved markedly with reclamation age: pH, conductivity, and salinity declined, whereas nitrogen, phosphorus, and potassium accumulated significantly (p < 0.001). Vegetation shifted from salt-tolerant pioneers (e.g., Suaeda salsa, Phragmites australis) to mixed communities and cultivated rice fields (Oryza sativa), reflecting progressive improvements in soil quality. Vegetation cover increased in parallel, with NDVI rising from 0.12 ± 0.05 (Y3) to 0.35 ± 0.09 (Y15), reflecting a shift from salt-tolerant pioneers to structurally complex communities. Mantel tests revealed strong positive associations of NDVI with organic matter, nitrogen, and phosphorus, and negative associations with pH, conductivity, and salinity. Structural equation modeling identified organic matter and nitrogen enrichment, along with declining pH and dissolved salts, as dominant drivers of vegetation recovery. These results highlight a co-evolutionary process in which soil improvement and vegetation succession reinforce one another, offering insights for ecological restoration and sustainable management in coastal reclamation landscapes. Full article

The aim of the study was to assess the impact of fertilizer type (urea, compound fertilizer), biodegradable coating type (linseed oil or hemp oil based) and nitrogen dose (135 and 180 kg N·ha⁻¹) on the yield of corn intended for silage. A three-year field experiment was conducted using a randomized block design with three replicates. The test plant was corn intended for silage. The field experiment was conducted in a factorial design comprising three experimental factors: fertilizer type (two levels), coating type (two levels), and fertilizer dose (two levels). Controlled-release fertilizers (CRF) based on biodegradable coatings are an emerging solution in sustainable nitrogen management, yet their field-scale performance remains insufficiently validated. This study investigated how biodegradable coatings based on linseed and hemp oils affect nutrient release dynamics and maize yield under three-year field conditions. The study represents the first field validation phase translating laboratory coating characteristics into agricultural performance metrics. Statistical analysis (ANOVA, Tukey’s test) showed that in the first year of the study, the greatest impact on plant height and corn yield was observed in the case of type of fertilizer used (η²_p up to 17.83%), type of coating (η²_p up to 63.15%) and their interaction (η²_p up to 11.92%). The symbol η²_p (partial eta squared) represents a measure of effect size in analysis of variance (ANOVA). The largest plant size (average 307–310 cm) and the highest yield (107.33 t·ha⁻¹) were obtained in the case of yields in which compound fertilizer or urea with coatings were used in relation to the series in which fertilizers without coatings were applied (differences up to 11 t·ha⁻¹). Statistical analysis using repeated measures ANOVA confirmed a significant time effect, with fertilizer effectiveness declining in subsequent years of the experiment (p < 0.05). In the experiment, no effect of the tested factors on the number of corn cobs was found (η²_p < 2.27%). The highest fresh matter yield for silage production was obtained with coated NPK compound fertilizer (98.80 t·ha⁻¹), representing a 48% increase compared to the unfertilized control (66.90 t·ha⁻¹). The results of the study indicate that the use of coated compound fertilizers—NPK has the most beneficial effect on yield and biometric parameters of plants in the first growing season after their soil application. The enhanced nutrient release from biodegradable coatings provided greatest benefits in the first growing season, with diminishing effects in subsequent years due to coating degradation and residual soil nutrient accumulation. Full article

The remediation of soils contaminated with heavy metals and radionuclides remains a significant environmental challenge. This study evaluated the phytoremediation potential of industrial hemp (Cannabis sativa L.) in soil collected from a historical evaporation dam, characterized by high levels of diverse metals, including Al, Cr, Fe, and radioactive elements (U, Th). Three treatments were applied: a control, a metal-spiked treatment (chelated with citric acid), and an NPK + spike treatment. A separate six-month greenhouse trial compared plants grown with and without NPK nutrients. Results demonstrated that the addition of a chelating agent significantly enhanced the bioavailability and subsequent uptake of key metals, including U, Se, and Pd. NPK fertilization combined with chelation resulted in the greatest plant biomass (≈4.5 g) and height (>18 cm), which correlated with higher total metal accumulation. Bioaccumulation factors (BAF > 1) were highest for B, Sr, Cd, and Bi, with values for Cd and U reaching 1.3 and 2.1, respectively. Foliar analysis revealed that leaves accumulated significantly higher metal concentrations than stems (e.g., Translocation Factor (TF) ~ 2.0 for Cd, Pb, and U), acting as the primary sink. This study concludes that hemp, particularly when assisted with chelating agents and adequate nutrition, is a highly effective candidate for the phytoremediation of multi-metal contaminated soils. The NPK + chelation strategy is the most promising for maximizing both biomass production and metal extraction efficiency. Full article

Compaction quality control in earthworks and pavements still relies mainly on density-based acceptance referenced to laboratory Proctor tests, which are costly, time-consuming, and spatially sparse. Lightweight dynamic cone penetrometer (LDCP) provides rapid indices, such as $q_{d0}$ and $q_{d1}$, yet acceptance thresholds commonly depend on ad hoc, site-specific calibrations. This study develops and validates a supervised machine learning framework that estimates $q_{d0}$, $q_{d1}$, and $Z_c$ directly from readily available soil descriptors (gradation, plasticity/activity, moisture/state variables, and GTR class) using a multi-campaign dataset of $n=360$ observations. While the framework does not remove the need for the standard soil characterization performed during design (e.g., W, ${\gamma }_{d,\mathrm{field}}$, and $R{C}_{\mathrm{SPC}}$), it reduces reliance on additional LDCP calibration campaigns to obtain device-specific reference curves. Models compared under a unified pipeline include regularized linear baselines, support vector regression, Random Forest, XGBoost, and a compact multilayer perceptron (MLP). The evaluation used a fixed 80/20 train–test split with 5-fold cross-validation on the training set and multiple error metrics ($R^2$, RMSE, MAE, and MAPE). Interpretability combined SHAP with permutation importance, 1D partial dependence (PDP), and accumulated local effects (ALE); calibration diagnostics and split-conformal prediction intervals connected the predictions to QA/QC decisions. A naïve GTR-average baseline was added for reference. Computation was lightweight. On the test set, the MLP attained the best accuracy for $q_{d1}$ ($R^2=0.794$, RMSE $=5.866$), with XGBoost close behind ($R^2=0.773$, RMSE $=6.155$). Paired bootstrap contrasts with Holm correction indicated that the MLP–XGBoost difference was not statistically significant. Explanations consistently highlighted density- and moisture-related variables (${\gamma }_{d,\mathrm{field}}$, $R{C}_{\mathrm{SPC}}$, and W) as dominant, with gradation/plasticity contributing second-order adjustments; these attributions are model-based and associational rather than causal. The results support interpretable, computationally efficient surrogates of LDCP indices that can complement density-based acceptance and enable risk-aware QA/QC via conformal prediction intervals. Full article

Soybean is a major source of plant-based protein and vegetable oil, but its productivity is severely limited by soil salinity. Transcription factors including NAC family play pivotal roles in regulating stress-responsive pathways. Here, we identified and characterized a salt-induced NAC transcription factor, GmNAC03, in soybean. Overexpression of GmNAC03 significantly improved salt tolerance at both the germination and seedling stages. Physiological analyses revealed that antioxidant enzyme activities, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were elevated in GmNAC03 transgenic lines, accompanied by reduced malondialdehyde (MDA) accumulation, indicating enhanced oxidative stress resistance. To further explore its regulatory mechanisms, RNA-seq analysis was performed, which showed that GmNAC03 overexpression affected pathways related to amino acid metabolism, particularly glutamine and aspartate family amino acid biosynthesis, as well as phenylpropanoid biosynthesis. Differentially expressed genes were enriched in alanine, aspartate, and glutamate metabolism, suggesting a role for GmNAC03 in metabolic reprogramming under salt stress. Together, these findings demonstrate that GmNAC03 functions as a positive regulator of salt tolerance in soybean by modulating antioxidant defense and amino acid metabolic pathways. This work provides new insights into the molecular basis of NAC-mediated stress adaptation and offers a potential target for breeding soybean varieties with enhanced salinity resistance. Full article

Cadmium (Cd) contamination in agricultural soils originates mainly from atmospheric deposition, irrigation water, fertilizers, pesticides, and industrial waste discharges. This human-induced pollution adversely affects soil fertility and structure, disrupts plant growth and physiological activities, and poses severe health risks through food-chain accumulation. Despite increasing research attention, comprehensive assessments that integrate global patterns, remediation strategies, and knowledge gaps remain limited. Therefore, this literature review critically synthesizes findings from 1060 peer-reviewed studies (screened using PRISMA guidelines) retrieved from Scopus and Web of Science databases, focusing on Cd sources, environmental behavior, plant responses, and soil remediation techniques. Results show that most research has been concentrated in Asia—particularly China—and Latin America. The most frequently investigated topics include Cd accumulation in crops, soil amendments, phytoremediation, and microbial-assisted remediation. Among remediation strategies, assisted phytoremediation and integrated biological–chemical approaches (biochar, PGPR, and soil amendments) emerged as the most promising for sustainable Cd mitigation. In conclusion, this review highlights regional disparities in research coverage, emphasizes the effectiveness of combined remediation approaches, and identifies the need for interdisciplinary and field-scale studies to advance sustainable solutions for Cd pollution control in agricultural systems. Full article

This study aims to evaluate the restoration effect of artificially mixed-sown grasslands by investigating the characteristics of plant communities and soil fungal communities in long-term (22-year-established) artificial grasslands under six Poaceae mixture combinations. The experiment took mixed-sown grasslands of grass species established in 2002 on the Qinghai–Tibet Plateau as the research object. It employed ITS gene high-throughput sequencing technology to construct a fungal community distribution map and combined it with FUNGuild (Functional Guilds of Fungi) functional predictions to analyze fungal species abundance, structural diversity, molecular co-occurrence networks, and functional characteristics. By integrating Mantel test and RDA (redundancy analysis), we identified key environmental factors driving soil microbial community structure in mixed-sown grasslands and revealed the plant–soil–microbe interaction mechanisms in a Poaceae mixture grassland. The results showed that the HC treatment (a mixture of three grass species) significantly enhanced plant biomass and soil nutrient accumulation. In 2023 and 2024, its aboveground biomass increased by 66.14% and 60.91%, respectively, compared to the HA treatment (monoculture). Soil organic matter increased by 52.32% and 48.35%, while electrical conductivity decreased by 48.99% and 51.72%, respectively. The fungal community structure improved under the HD treatment (a mixture of four grass species), with an increased abundance of the dominant phylum Ascomycota and a 14.44% rise in the Shannon index compared to the HA treatment. The network complexity under the HF treatment (a mixture of six grass species) increased (with edge numbers reaching 494), while the functional abundance of plant pathogen was significantly lower than that under the HA treatment. Mantel test and RDA revealed that SEC (soil electrical conductivity) was significantly positively correlated with pH, while both exhibited negative correlations with other plant and soil physicochemical indicators. Moreover, SEC emerged as the core factor driving fungal community assembly. Mixed sowing of three to four grass species effectively regulated soil electrical conductivity, simultaneously enhancing plant biomass, soil nutrients, and fungal community diversity, representing an optimal strategy for artificial restoration of degraded grasslands. Full article