Search Results (1,473)

Degraded grey desert soils are characterized by severe nutrient deficiencies and structural compaction. This study elucidated how biogas slurry drip irrigation regulates the micro-pore architecture, fertility, and macroscopic hydraulic properties. A one-year field experiment was conducted using a completely randomized design with three replications. The experimentation included three irrigation levels (W1: 70% W, W2: 85% W, and W3: 100% W, where W is full irrigation) and three slurry ratios (S1: 60% S, S2: 80% S, and S3: 100% S, where S is the annual nitrogen application rate of 93 kg ha⁻¹), with undisturbed (CK) and chemical fertilizer (CF) controls. Surface soil samples (0–20 cm) were analyzed based on treatment averages using scanning electron microscopy and the van Genuchten (vG) model. The results indicated that W3S2 increased the total porosity to a peak of 42.39% compared with the CK baseline of 25.25%, while expanding the mean pore diameter to 9.24 μm. Concurrently, the application minimized the morphological pore fragmentation, reducing the fractal dimension from 1.82 under CK to 1.61 under W3S3. Although the macroscopic porosity expanded, the effective saturated water content decreased. We hypothesize that this reduction is driven by partial micropore clogging by organic coatings. This mitigated the excessive near-saturation water retention and accelerated drainage, while significantly increasing the specific water capacity at 100–1000 kPa suctions to delay moisture depletion. W2S3 (85% W, 100% S) performed favorably with regard to soil fertility and water retention stability. The W2S3 treatment optimized soil fertility and water retention stability by achieving peak concentrations of 17.69 g kg⁻¹ for SOM and 1.31 g kg⁻¹ for TN. Path analysis suggested that physical microstructural traits dominate macroscopic hydraulic regulation. In conclusion, biogas slurry drip irrigation provides a sustainable framework to optimize structural and hydraulic resilience in dryland agriculture. Full article

Water scarcity in semi-arid regions threatens seed germination and early crop establishment, driving the development of biodegradable Nature-based Solutions to replace synthetic plastic mulches. Porous cellulose membranes were fabricated from rice husk (RH), banana pseudostem (BP), and sugarcane bagasse (SB) by thermo-chemical extraction and high-shear homogenization (n = 5 replicates per membrane type). Membranes were characterized by ATR-FTIR and scanning electron microscopy, confirming removal of non-cellulosic components and biogenic silica preservation in RH, and revealing biomass-dependent porous architectures linked to mechanical and transport behavior. RH produced the most compact fibrillar matrix (compressive strength: 8.16 ± 0.24 MPa; WVT: 170 ± 60 g m⁻² day⁻¹), BP an open interconnected network with superior deformability (9.83 ± 0.25% elongation) and moisture transport (WVT: 400 ± 100 g m⁻² day⁻¹), and SB the highest moisture-retention capacity (215.7 ± 15.8%). Germination assays with Brassica oleracea var. botrytis under water stress showed SB achieved the highest germination rate (90.5 ± 0.99%), confirming that sustained moisture availability governs germination more decisively than transport rate alone. Soil burial tests confirmed biodegradable behavior across all membranes (R² ≥ 0.995; k = 0.043–0.046 day⁻¹). These findings establish a hydrogen-bond-mediated structure–property–function framework for designing biomass-specific cellulose membranes as biodegradable solutions for water-limited agricultural systems. Full article

This study presents a compact controlled urban geophysics test site developed at the University of Malta to evaluate the response of complementary near-surface sensing methods under known shallow subsurface conditions. The experimental setup is designed to investigate buried target detection and the response to a simulated shallow leak, used here as a controlled water-release experiment in a shallow carbonate setting characterized by thin, laterally variable soil cover and anthropogenic disturbance. A preliminary passive seismic survey based on the horizontal-to-vertical spectral ratio (HVSR) method was used to compare candidate sectors and select the most suitable area for installation. The test site includes a buried iron plate and a perforated PVC pipe, the latter used to release water under controlled shallow conditions. Ground-penetrating radar (GPR), smartphone magnetometry, electrical resistivity tomography (ERT), and UAV-based thermal imaging were applied to assess target detectability and leak-related surface–subsurface responses. Results show that GPR provides the clearest response for static target detection, while smartphone magnetometry identifies the buried ferrous target under favourable conditions. For the simulated leak experiment, ERT provides the most robust subsurface evidence of moisture redistribution after water injection. UAV thermal imaging captures a complementary surface thermal response influenced by both moisture dynamics and local surface disturbance. The results show that a compact controlled test site can support the comparison of professional and low-cost sensing methods for shallow target detection and simulated leak assessment. In this configuration, the controlled water-release experiment provides a practical basis for evaluating leak-related surface–subsurface responses under known shallow conditions. The proposed setup has implications for methodological assessment, training, and near-surface environmental monitoring in heterogeneous urban settings. Full article

Lime-based stabilization of clayey soils remains a cornerstone of ground improvement, yet the high carbon footprint of lime production drives the search for sustainable supplementary binders derived from industrial and quarrying wastes. Volcanic tuff waste (VTW), a fine powder by-product of wet cutting of ignimbritic tuff blocks, is an underutilized quarrying residue, already fine enough to use directly without grinding or thermal processing, yet its use as a supplementary binder in lime-stabilized clays has not been systematically investigated. This study evaluates VTW sourced from Ahlat (Bitlis, Türkiye) in kaolin clay stabilized with 6% lime, with VTW added at 0%, 10%, 15%, and 20% by dry weight. Mixtures were characterized through Atterberg limits, compaction, unconfined compressive strength (UCS) at 1–28 days, California Bearing Ratio (CBR), XRD, SEM, and FTIR. VTW reduced plasticity index, increased maximum dry density, and lowered optimum moisture content. The 15% VTW mixture achieved the highest 28-day UCS of 4296 kPa, a 17.2% improvement over the lime-only control, and the highest CBR of 80%. XRD revealed Tobermorite 9 Å formation, while SEM and FTIR confirmed cementitious gel phases consistent with pozzolanic reactions. The findings demonstrate that ignimbritic VTW, used directly without processing, is an effective supplementary binder that partially replaces carbon-intensive lime, supporting low-carbon, cost-effective stabilization and the valorization of quarrying waste within a circular economy framework. Full article

Surface erosion of loess slopes in arid and semi-arid regions of China remains a critical geotechnical issue, requiring green and low-carbon stabilization techniques. This study investigated the effectiveness of enzyme-induced carbonate precipitation (EICP) for the surface spraying reinforcement of Q3 loess collected from a high-fill engineering site at Yan’an University. Single-factor tests, response surface methodology (RSM), surface strength tests, CT-based three-dimensional pore reconstruction, and scanning electron microscopy (SEM) were conducted to evaluate the effects of cementation solution concentration and spraying dosage. The cementation solution was prepared by mixing analytical-grade urea and anhydrous calcium chloride at a 1:1 molar ratio, and the specimens were compacted to a dry density of 1.4 g/cm³. The results showed that surface strength first increased and then decreased with increasing cementation solution concentration and spraying dosage. Spraying dosage had a more pronounced influence than cementation solution concentration; excessive spraying above 9 L/m² reduced surface strength because of the high water sensitivity of loess. Five replicate tests at the central point were conducted to evaluate experimental error. The optimal parameters were 1.5 mol/L for cementation solution concentration and 9 L/m² for spraying dosage. CT and SEM results showed that CaCO₃ precipitation filled large pores and cemented soil particles, reducing total porosity from 6.7% to approximately 4.0%. These findings indicate that EICP improves loess surface strength mainly through pore filling and particle cementation, providing guidance for the ecological protection of loess slopes. Full article

This study investigated the impact of recreational use on trails in the Atlantic Forest (Ubatuba Municipality, São Paulo State, Brazil) using physical, chemical and geochemical indicators. Five trails with different morphological characteristics were selected, and paired samples were collected from the trail surface (TR) and trail-side slope (TA). The statistical approach combined local analyses for each trail with global clustering (n = 19) using Student’s t-test, along with multivariate modeling through Principal Component Analysis (PCA) and Pearson correlation. The analysis included physical attributes (bulk density, particle size and porosity), chemical attributes (pH, organic matter and macronutrients) and geochemical compositions (major oxides and trace elements determined by XRF). The overall results reveal systematic compaction in the trail surface (TR), with bulk density increasing from 1.32 g/cm³ (TA) to 1.37 g/cm³ (TR) (p = 0.038), and total porosity decreasing from 47.26% to 45.34% (p = 0.016). In contrast, the geochemical oxide composition (SiO₂, Al₂O₃, Fe₂O₃) remained stable (p > 0.05), indicating the resilience of the mineral matrix. However, significant local dynamics (p < 0.05) in K₂O and MgO were observed in more preserved trails, associated with surface compaction and fragmentation of the litter layer, and phosphorus showed strong dependence on organic matter (r = 0.85). Multivariate analysis indicates that degradation is predominantly physical and micromorphological at the local scale, with bulk density and porosity being the most sensitive indicators for environmental monitoring. Full article

Seasonal freeze–thaw cycling progressively rearranges pores and propagates microcracks in silty clay, reducing the reliability of cold-region earthworks. This study evaluated a bio–polymer stabilization strategy combining microbially induced carbonate precipitation (MICP) with anionic polyacrylamide (APAM) to improve mechanical performance and freeze–thaw durability. Six groups were prepared at identical moisture and compaction conditions: water, APAM, and four MICP–APAM groups with bacterial optical densities (OD600) of 0.8, 1.0, 1.2, and 1.4. Unconfined compressive strength, unconsolidated-undrained triaxial compression, ultrasonic pulse velocity, and SEM, TG/DTG, XRD, and FTIR analyses were conducted before and after freeze–thaw cycling. The M1.0-APAM group showed the best overall performance, with UCS values of 1.35 MPa before cycling and 0.89 MPa after nine cycles, together with high shear resistance and ultrasonic velocity. Lower bacterial concentration provided insufficient cementation, whereas higher concentrations promoted non-uniform carbonate deposition, pore heterogeneity, and local stress concentration. Microstructural evidence indicated that OD600 ≈ 1.0 produced a relatively homogeneous network of fine carbonate clusters and polymer-associated films, with calcite formation supported by TG/DTG and XRD. The results show that MICP–APAM treatment enhances silty clay primarily through coordinated mineralization uniformity, pore refinement, and polymer bridging, providing a sustainable stabilization option for seasonally frozen soils. Full article

Abandoned slopes often encounter problems such as compacted soil and lack of nutrients. Biochar, as a promising soil amendment agent, can effectively enhance soil fertility. Moreover, evaluating the nutrient and microbial characteristics during the improvement process is of great significance for revealing its mechanism of action in improving abandoned land. This study analyzed the characteristics of soil nutrients, microbial community structure, and co-occurrence network after reclamation under different application rates (0%, 1%, 2.5%, 4%, 5.5%, hereinafter referred to as CK, T1, T2, T3, T4) of corn straw biochar. The results showed that biochar significantly increased soil organic carbon (by 60.74–164.82%), total nitrogen (11.31–27.73%), and total phosphorus (13.32–56.03%) content, and the effect was best at a rate of 4% (T3). With the increase in biochar application rate, soil bulk density generally showed a downward trend, and pH generally showed an upward trend. Significant levels (p < 0.05) were reached from T2 to T4. There was a strong linear correlation between biochar application rate and soil organic matter, total nitrogen, and pH in the fitted model, with R² values reaching 0.753, 0.601, and 0.706, respectively. Microbial community analysis showed that biochar application changed the bacterial community structure. With the increase in soil depth, the Shannon index and Chao index of each treatment generally increased, indicating that soil depth is one of the key factors regulating the community structure. Biochar application promoted the proliferation of beneficial bacterial groups such as Pseudomonadota and Acidobacteriota, by increasing the number of co-occurrence network nodes and edges enhancing the complexity and stability of the microbial network. Full article

Flooding triggered by intense precipitation is a significant natural hazard affecting Mediterranean regions, where complex terrain, rapid hydrological response and increasing urbanization can amplify flood impacts. This study assesses flood susceptibility in two representative Mediterranean River catchments: the Koiliaris in Crete, Greece, and the Pediaios in Cyprus. A compact Flood Hazard Index (FHI) was developed by integrating the Topographic Wetness Index (TWI), Curve Number (CN), and R20 heavy rain frequency index, representing the principal geomorphological, hydrological and climatological controls of flood generation. Spatial datasets including EU-DEM elevation data, CORINE land cover, European soil databases, and Copernicus CERRA precipitation reanalysis were combined within a GIS-based multi-criteria framework using Analytic Hierarchy Process weighting. The resulting FHI maps identify high flood susceptibility along river corridors, low-lying accumulation zones, and urbanized areas. In the Koiliaris basin, 34% of the area fell within the high and very high susceptibility classes, mainly in downstream alluvial zones, whereas in the Pediaios basin, 29% of the area fell within the high and very high susceptibility classes, concentrated around the urbanized Nicosia corridor. The analysis of historical flood events provided a qualitative consistency assessment of the FHI patterns, acknowledging that the absence of spatially explicit flood-inundation footprints limits quantitative validation. Full article

Soil is prone to structural degradation under water infiltration, and the combined effects of dry density and salinity further complicate its hydraulic conductivity and drying shrinkage behavior. However, previous studies have primarily focused on single factors, and the interactive mechanisms between compaction state and salinity remain poorly understood. To investigate the hydraulic conductivity and drying shrinkage behavior of soil under different dry densities and salinity levels, this study examined three dry densities (1.30, 1.35, 1.45 g/cm³) and four NaCl contents (0, 0.5%, 2%, 6%). Saturated hydraulic conductivity (ks) and drying shrinkage were systematically measured. The results indicate that dry density is the primary factor controlling pore structure evolution, ks and drying shrinkage behavior. Increasing dry density markedly reduced porosity (up to 15.95%), ks (by 57.14–92.91%), and drying shrinkage. In contrast, salinity exhibited non-monotonic, density-dependent effects. Salts increased porosity through electrochemical interactions and crystallization-induced pore support, but their effects on ks and drying shrinkage displayed threshold and reversal behavior. These coupled effects demonstrate strong nonlinearity and density dependence, providing a mechanistic basis for compaction optimization and the stability assessment of soil under saline conditions. Full article

This study evaluates the multi-year taxonomic diversity and functional structure of beetle assemblages (Coleoptera) within Sub Arini Park, a historic urban green space in Sibiu, Romania. Following a preliminary baseline and methodological calibration phase in 2023, systematic monitoring was conducted during the 2024 and 2025 seasonal cycles utilizing standardized pitfall trapping across diverse park zones. We explicitly tested two hypotheses: (H1) that long-standing historic park management preserves a resilient and functional insect community structure, and (H2) that local spatial heterogeneity and microhabitat variations significantly drive species distribution. A total of 14,843 individuals belonging to 39 species were analyzed. While total abundance exhibited a slight decrease from 2024 (N = 7112) to 2025 (N = 6551), true diversity metrics (Hill numbers) revealed a significant increase in raw species richness (q = 0) from 30 to 39 species, alongside an enhanced equity of frequent species (Shannon diversity, q = 1, increased from 4.26 to 5.12). Functional guild analysis and multivariate PCA demonstrated a highly structured biocenotic distribution; specialist and hygrophilous species (e.g., Carabus variolosus Fabricius, 1787) were strictly constrained to high-humidity riparian corridors, whereas thermophilous generalists dominated open lawns under high anthropogenic stress. Our spatial analysis identified critical degradation within these heavily managed zones, specifically driven by intensive mowing, soil compaction, and organic debris removal. These findings confirm both hypotheses, revealing that the park operates as a heterogeneous mosaic of ecological refugia rather than a uniform habitat block. Crucially, this study provides a concrete, quantitative basis—derived from empirical thresholds of species richness, abundance shifts, and mapped microhabitat preferences—for implementing nature-based management strategies (such as establishing buffer zones with reduced mowing frequencies, limiting trampling, and retaining coarse woody debris) aimed at mitigating urban biodiversity loss and maintaining vital biological pest control services in Central–Eastern Europe. Full article

With increasing constraints on extensive farming—including soil degradation, salinisation and more frequent climatic anomalies—the development of ‘smart’ agriculture requires the integration of affordable, non-invasive methods for monitoring the physiological state of plants. A key indicator for assessing productivity and the early detection of stress is the rate of photosynthetic CO₂ assimilation (A); however, widely available commercial gas analysers are characterised by high cost, technical complexity and considerable weight, which limits their use in large-scale field studies. Here, a new handheld system for measuring assimilation was developed and tested, based on the accumulative principle of recording changes in CO₂ concentration using simple infrared sensors and without maintaining a constant air flow around the leaf. A comparison was carried out between a prototype of the developed system and a commercial gas analyser when measuring leaf assimilation under irrigation and simulated drought conditions. The results demonstrated the consistency of the readings from the two systems. The developed system is characterised by its compact size, low cost, and the absence of moving parts and consumables. The proposed system has the potential to be effective for large-scale screening tasks and rapid diagnosis of stress-induced changes; it represents a promising, affordable tool for addressing applied tasks in precision agriculture, environmental monitoring and physiological research. Full article

Rapid dissolution of conventional fertilizers causes low nutrient-use efficiency and serious leaching losses, contributing to agricultural non-point source pollution. In this study, biomass-based slow-release fertilizer beads were prepared by ionic crosslinking of potato starch (ST), chitosan (CS), and corn-straw biochar (BC), using potassium nitrate (KNO₃) as the model nutrient. The effects of ST/CS ratio and BC incorporation on bead structure, swelling, nutrient loading, release kinetics, and soil-column leaching were systematically investigated. Biochar incorporation formed a more compact and interconnected porous network and reduced the equilibrium swelling ratios of ST90/CS10, ST80/CS20, and ST70/CS30 from 188%, 176%, and 164% to 168%, 136%, and 104%, respectively. Although BC slightly decreased KNO₃ loading capacity, it markedly slowed nutrient release; ST80/CS20/BC20 released 31.09%, 50.09%, and 81.82% of loaded KNO₃ at 24, 72, and 504 h, respectively, which were 28.40%, 25.27%, and 11.30% lower than those of ST80/CS20. Kinetic fitting indicated that BC reduced the apparent release rate and promoted diffusion-controlled release behavior. Soil-column experiments further showed that the beads reduced NO₃⁻-N and K⁺ leaching compared with free KNO₃, with ST80/CS20/BC20 showing the best balance between nutrient loading and release control. These results suggest that starch–chitosan–biochar beads are a promising biodegradable matrix for slow-release fertilizer applications. Full article

Residual film recovery is a crucial approach to mitigating agricultural “white pollution” and ensuring sustainable land use. Currently, the development of residual film recovery machines relies primarily on theoretical analysis and field performance tests. The lack of support from computational simulation models often leads to suboptimal mechanical performance, severely restricting the design and optimization of recovery equipment. To address this, this study proposes a method for constructing and experimentally validating a discrete element model of plow-layer residual film using EDEM software. First, field tests were conducted to measure soil compaction and residual film distribution at various depths. The ultimate tensile force of the residual film was also evaluated to provide fundamental data for model development. Using the Hertz–Mindlin with bonding contact model in EDEM, the intrinsic parameters of the residual film were selected and optimized. Combined with a Box–Behnken experimental design, a quadratic regression model relating normal stiffness per unit area, critical normal stress, and bond radius to the ultimate tensile force of the film was constructed. The optimal parameter combination was determined as follows: normal stiffness = 1.11 × 10⁶ N·m⁻³, critical normal stress = 2.45 × 10⁶ Pa, and bond radius = 0.03 mm. Under these parameters, the theoretically predicted ultimate tensile force was 1.18 N, and the simulated value yielded a relative error of only 1.69%, validating the effectiveness of the single-film model. Furthermore, using the field-measured data, a coupled film–soil model was established via the “rainfall” method to conduct simulated penetration tests. Parameter calibration was executed using the multivariate Newton–Raphson iteration method. The optimal bonding parameters for soil particles were identified as follows: normal stiffness per unit area = 9.6 × 10⁵ N/m², shear stiffness per unit area = 9.6 × 10⁵ N/m², critical normal stress = 5.38 × 10⁵ Pa, critical shear stress = 5.38 × 10⁵ Pa, and bond radius = 4.3 mm. The average simulated penetration resistance was 59.61 N, showing a relative error of 5.91% compared to the field-measured value of 56.28 N. These results demonstrate that the developed coupled film–soil DEM can be effectively applied to simulate the lifting and throwing processes of plow-layer residual film recovery machines, thereby providing vital modeling support for the design and optimization of residual film recovery mechanisms. Full article

Soil moisture (SM) governs land–atmosphere exchanges and strongly influences agricultural management and hydrological assessment, yet high-resolution mapping remains challenging due to sensor-specific confounding effects and limited field observations. This study develops a practical workflow for point-scale SM estimation and wall-to-wall mapping by integrating multi-sensor remote sensing predictors with ensemble learning. A compact predictor set was constructed from Sentinel-2 optical indices, Sentinel-1 SAR descriptors (σVV and the polarization ratio σVH/σVV), and topographic information, collocated with in situ SM measurements along a transect in the study area. Three tree-based regressors—Random Forest, XGBoost, and CatBoost—were trained under an identical feature configuration and evaluated using R², Root Mean Square Error (RMSE), and Mean Absolute Error (MAE) together with predicted–observed diagnostics. A stacking ensemble was then implemented using leakage-controlled K-fold out-of-fold predictions to generate meta-features, with a Decision Tree as the meta-learner tuned via a grid search. Results show that base learners achieve comparable skill (R² ≈ 0.60–0.62; RMSE ≈ 0.038–0.039), while stacking improves test accuracy (RMSE = 0.0346) and provides a stable mapping-ready model. The trained framework was transferred to stacked raster predictors to produce spatially continuous SM maps, revealing coherent moisture heterogeneity across the region. Accordingly, the objective of this study is to develop a compact and application-oriented point-to-map workflow for high-resolution soil moisture estimation by integrating Sentinel-1/2-derived predictors with stacking-based model fusion, rather than to propose a new physically based retrieval model. Full article