Search Results (667)

Agroforestry intercropping is increasingly recognized for improving soil quality and crop productivity, yet its effects on soil nutrient dynamics, enzyme activities across soil profiles, and tea yield remain insufficiently understood. Here, we assessed how four systems—monoculture tea (CK), Osmanthus–tea (OT), Michelia–tea (MT), and Osmanthus–Michelia–tea (OMT)—influence soil properties and spring tea yield in hilly plantations of southern China. Across systems, the OMT configuration produced the highest spring tea yield, representing a 39.5% increase relative to CK, accompanied by a 19.0% increase in tea bud density. In the 0–20 cm soil layer, OMT markedly enhanced soil organic matter by 48.4%, total nitrogen by 25.8%, and available nitrogen and phosphorus by 24.9% and significant margins, respectively, while also stimulating enzyme activities—urease (+34.1%), sucrase (+17.2%), dehydrogenase (+43.9%), amylase (+17.2%), and cellulase (+60.7%). In the 20–40 cm layer, OMT increased soil organic matter (+48.4%), total nitrogen (+25.8%), and available nitrogen, and elevated key enzyme activities, including sucrase (+46.5%), acid phosphatase (+16.3%), and polyphenol oxidase (+20.1%). Correlation and principal component analyses further revealed strong positive associations among nutrient enrichment, enzyme activation, and tea yield. These findings demonstrate that the OMT agroforestry configuration enhances nutrient availability and enzymatic function throughout the soil profile, thereby promoting higher tea yield. Overall, OMT substantially improved spring-season soil fertility and productivity, highlighting its potential for sustainable tea plantation management. Full article

Offshore wind turbines are subjected to environmental loads such as wind and ocean waves throughout their entire service lives. Saturated sandy soils experience liquefaction under cyclic shear stresses induced by earthquakes or strong wave actions, which can result in the tilting, settlement, or even overturning of structures. This study investigates the effect of fine content (FC) on the liquefaction resistance (CRR) of saturated sandy soils with different density states. Sandy soils with varying FC values are examined under three scenarios: (1) constant relative density; (2) constant void ratio; and (3) constant skeleton void ratio. A series of undrained cyclic triaxial tests are conducted on sandy soils with different FC and density states (D_r, e, and e_sk). The results indicate that an increase in FC leads to a decrease in CRR at constant D_r or e, whereas CRR at constant e_sk increases with increasing FC. No clear correlation is observed between D_r, e, or e_sk and CRR for saturated sandy soils with varying FC. Since e_sk does not account for the effect of fine particles on the contact state of skeleton particles, the equivalent skeleton void ratio (e_sk^*) is introduced to describe the particle contact state of sandy soils with different fine contents (FCs), considering the degree of fine particle participation. In addition, the test data reveal that the CRR of sandy soils with different FC and density states decreases with increasing e_sk^*, and a power relationship between the reduction in CRR and the increase in e_sk^* is established. This finding indicates that e_sk^*, which considers the proportion of fines contributing to the load-sustaining framework, serves as a reliable index for evaluating the CRR of various sandy soils. We find that grain shape plays a significant role in influencing CRR, and the overall CRR of sandy soils increases as the grain shape changes from spherical to angular, compared to the published test results for other sandy soils. Full article

Sustainable forest management requires a comprehensive understanding of how stand density regulates soil ecological processes. We examined a Larix principis-rupprechtii plantation under three thinning retention densities (High—HD; Medium—MD; Low—LD) and an unthinned control (CK), with soil samples collected from four depth layers (0–10, 10–20, 20–30, and 30–40 cm). This study investigated the effects of stand density on soil properties and microbial communities in a Larix principis-rupprechtii plantation by combining high-throughput sequencing with soil physicochemical analysis to identify the optimal density regime for maintaining soil health. Results demonstrated the following: (1) Moderate-density (MD) management best balanced the stability of soil ecosystem structure, showing superior water retention, organic carbon content, and microbial diversity in the 0–30 cm soil layer. The mechanism underlying these improvements can be attributed to the moderately open canopy structure in MD stands, which facilitated efficient litter decomposition and drove functional complementarity between Basidiomycota (enhancing cellulose degradation capacity) and Acidobacteriota (adapted to oligotrophic conditions). (2) Redundancy analysis revealed that soil pH and available nutrients (AK, AP) were key environmental factors driving microbial community restructuring: Actinobacteriota dominated in neutral, phosphorus-rich environments, while Acidobacteriota thrived under acidic, phosphorus-limited conditions. Fungal communities showed high sensitivity to management intensity, with significant shifts between Ascomycota and Basidiomycota, whereas bacterial communities remained relatively stable due to functional redundancy. We recommend the adoption of moderate-density management as a sustainable practice to enhance soil nutrient cycling and maintain microbial diversity, thereby providing scientific support for sustainable plantation management. Full article

Background: Winch-assisted harvesting is an alternative to traditional cable yarding on steep slopes, offering improved operational efficiency and fewer limitations. Knowledge on the effects of winch-assisted harvesting on soil disturbance are limited. This study aimed to assess the effects of winch-assisted and conventional tracked harvester operations on soil compaction and machine slippage in a clear-cut stand with sandy loam soil. Methods: We evaluated changes in soil physical properties, in depth and extent, along machine operating corridors with and without winch-assist across slope gradients ranging from 30% to 52% and up to three machine passes. Results: The relative increase in bulk density differed between treatments. In the non-assisted corridors, the bulk density increased by 18%, 12%, and 11% at depths of 0–10, 10–20, and 20–30 cm, respectively; the winch-assisted corridors showed smaller increases of 12%, 5%, and 3% at the corresponding depths. The winch-assisted plots did not show a significant reduction in rut depth compared with the non-assisted plots, a result likely influenced by site-specific dry soil conditions. Conclusions: These results highlight the potential of winch-assisted systems to reduce horizontal soil disturbance, though their effectiveness in limiting rutting remains variable under dry conditions. Full article

This study aimed to evaluate the physiological responses and yield of Tahiti lime (Citrus latifolia) cultivated at high density under three soil moisture tension (SMT) levels: low (L = −0.010 MPa), medium (M = −0.035 MPa), and high (H = −0.085 MPa). Measurements included water status, sap flow, photochemical activity, gas exchange, and fruit yield during the dry and early rainy seasons. The leaf water potential (Ψ_L) and relative water content (RWC) were higher in the L and M treatments than in H, with an overall improvement at the onset of the rainy season. From the dry to the rainy season, sap flow decreased by 25.3, 16.0, and 1.9 L day⁻¹ in L, M, and H plants, respectively. Plants with higher soil water availability (L and M) maintained better water status during the dry season, which favored photochemistry and gas exchange, reflected in a greater shoot growth and fruit yield (54.5 and 53.4 kg plant⁻¹, respectively). In contrast, H SMT significantly reduced water relations and photosynthetic activity, leading to yield loss. Short-term rainfall (six days) was insufficient to restore physiological performance. Maintaining SMT around −0.035 MPa during the dry season optimizes yield while reducing water use. Full article

Soil compaction from repeated mechanized traffic in sugarcane cultivation reduces porosity, root growth, water infiltration and nutrient availability. Pre-consolidation stresses (σP) in sugarcane soils (70–210 kPa) are frequently exceeded by machine loads up to 595 kPa, producing bulk density (ρb) above 1.65 Mg m⁻³ and soil resistance to penetration (SR) beyond 2.0 MPa within the upper 0.40 m; approximately 80% of root biomass concentrates in this zone. Conventional whole-area subsoiling is energy-intensive, destabilizes soil structure and accelerates re-compaction, limiting long-term efficacy. This review proposes integrating strip soil tillage (SST) with controlled traffic farming (CTF) via a multifunctional implement that performs selective subsoiling, in-row chemical correction and targeted input application. The system is designed to mobilize 53% of the area, preserve inter-row structure, reduce fuel consumption by 43.5%, decrease CO₂ emissions by 163–315.4 kg ha⁻¹ and lower operational costs by 53.5% relative to conventional approaches. The implement features adjustable-depth subsoiler shanks with dedicated input dispensers, rotary hoes for organic amendment incorporation and GNSS-guided autopilot for precise in-row operations. Expected outcomes include improved soil physical quality, enhanced root development beyond 1.30 m, increased input-use efficiency and sustainable productivity gains under CTF–SST management. This review is innovative in explicitly proposing and detailing the integration of CTF with SST through a multifunctional implement. This approach advances current knowledge by overcoming the main limitations of conventional soil tillage systems, such as accelerated recompaction, high energy consumption, and inefficient input use, while promoting measurable improvements in soil physical quality, operational efficiency, and sustainable productivity. A literature review search up to 31 May 2025 supported the integration of SST and CTF as a viable strategy for sustainable soil management in sugarcane production. Full article

To clarify the role and mechanism of sod-seeding patterns in improving soil fertility and mitigating nitrous oxide (N₂O) emissions in peach orchards, we conducted a study since 2023. Taking clean tillage (CK) as the control, three sod-seeding patterns—Trifolium repens–Lolium perenne mixed sowing (TPr), T. repens single sowing (Tr), and L. perenne single sowing (Pr)—were tested to analyze soil physicochemical properties, nitrogen cycle functional genes, and N₂O emission-related genes, and to explore the driving mechanism of N₂O mitigation. Results showed that all three sod-seeding patterns significantly reduced soil pH and bulk density, increased soil electrical conductivity and mean aggregate size, and improved soil nutrient status compared with CK; TPr performed best, significantly enhancing soil enzyme activities related to carbon and nitrogen cycles. Sod-seeding patterns had no significant effect on genes involved in assimilatory nitrate reduction, denitrification, or nitrification, but significantly increased dissimilatory nitrate reduction (DNRA) and nitrogen degradation gene abundances, and reduced N₂O-producing gene (amoA + amoB, nirS + nirK) abundances. Field monitoring indicated TPr reduced N₂O emissions by 34.0%, 35.7%, and 41.0%, relative to CK, Pr, and Tr, respectively. Structural equation modeling revealed that sod-seeding reduced N₂O emissions mainly by decreasing soil NH₄⁺-N content and nirS + nirK abundance. In conclusion, sod-seeding patterns improve soil fertility and mitigate N₂O emissions in peach orchards, with TPr showing the best comprehensive benefits. Full article

Accurate detection of machinery-induced strip roads after forest operations is fundamental for assessing soil disturbance and supporting sustainable forest management. However, in Mediterranean pine forests where canopy openings after boom-corridor thinning are moderate, the effectiveness of different remote sensing techniques remains uncertain. Previous studies have shown that LiDAR-based methods can reliably detect logging trails in different forest stands, but their direct transfer to structurally simpler, even-aged Mediterranean stands has not been validated. This study addresses this gap by testing whether UAV-derived RGB imagery can achieve comparable accuracy to LiDAR-based methods under the canopy conditions of boom-corridor thinning. We compared four approaches for detecting strip roads in a black pine (Pinus nigra Arn.) plantation on Mount Amiata (Tuscany, Italy): one based on high-resolution UAV RGB imagery and three based on LiDAR data, namely Hillshading (Hill), Local Relief Model (LRM), and Relative Density Model (RDM). The RDM method was specifically adapted to Mediterranean conditions by redefining its return-density height interval (1–30 cm) to better capture areas of bare soil typical of recently trafficked strip roads. Accuracy was evaluated against a GNSS-derived control map using nine performance metrics and a balanced subsampling framework with bootstrapped confidence intervals and ANOVA-based statistical comparisons. Results confirmed that UAV-RGB imagery provides reliable detection of strip roads under moderate canopy openings (accuracy = 0.64, Kappa = 0.27), while the parameter-tuned RDM achieved the highest accuracy and recall (accuracy = 0.75, Kappa = 0.49). This study demonstrates that RGB-based mapping can serve as a cost-effective solution for operational monitoring, while a properly tuned RDM provides the most robust performance when computational resources are sufficient to work on large point clouds. By adapting the RDM to Mediterranean forest conditions and validating the effectiveness of low-cost UAV-RGB surveys, this study bridges a key methodological gap in post-harvest disturbance mapping, offering forest managers practical, scalable tools to monitor soil impacts and support sustainable mechanized harvesting. Full article

Understanding the mechanisms of mineral dissolution at the atomic scale is crucial for interpreting geochemical processes in soils and sediments, particularly those involving clay minerals. This study addresses the dissolution of pyrophyllite, a model dioctahedral phyllosilicate, under acidic conditions by employing Density Functional Theory (DFT) to simulate protolysis reactions at four distinct edge surfaces ({100}, {010}, {110}, and {130}). Molecular cluster models were constructed for each edge, and the interactions of protons and hydronium ions with various oxygen sites were systematically analyzed. The results demonstrate that bridge oxygens, especially those coordinated to one silicon and two aluminum atoms, are the most reactive sites, undergoing significant bond breaking and structural distortion upon protonation, while hydroxyl groups mainly accommodate structural changes without initiating dissolution. The {110} edge was found to be the least reactive, whereas the {100}, {010}, and {130} edges exhibited the highest reactivity. Hydronium ions produced similar or greater structural changes compared to protons, with water molecules forming hydrogen bonds with the resulting structures. These findings confirm that protonation of bridge oxygens is the rate-limiting step in phyllosilicate dissolution, and that octahedral cations are released preferentially over tetrahedral ones. These findings are consistent with the conclusions drawn from the dissolution experiments. This study provides atomistic information on the dissolution mechanisms of clay minerals at a scale that exceeds the capabilities of dissolution experiments, emphasizing the importance of edge reactivity relative to extensive basal surfaces and the role of water in proton transfer and facilitating protolysis reactions. Full article

The soil–water retention curve (SWRC) is a fundamental property that governs the hydraulic and mechanical behavior of unsaturated soils. Laboratory SWRC determination remains time-consuming and costly, promoting indirect estimation methods. However, existing methods often oversimplify the pore structure and particle arrangement of soils and neglect the effect of capillary menisci, resulting in discrepancies from natural soil behavior. This study proposes a novel method to estimate the SWRC of coarse-grained soils based on grain size distribution (GSD) and relative density. In the proposed method, soil particles are idealized as spheres in a two-dimensional (2D) plane, and the packing structure is modeled using representative quadrilaterals composed of four poly-disperse particles. The GSD is employed to calculate the probability of different particle sizes occupying the corners of the quadrilateral elements, while the relative density defines their geometric configuration. The water retention behavior is then evaluated using the geometric relationships between the air–water interface and particle radii. The predicted SWRCs are in good agreement with experimental data, indicating that the method can effectively capture the water retention characteristics of coarse-grained soils governed by capillary effects. The method’s applicability is limited to coarse-grained soils and excludes clayey soils where adsorbed water dominates retention mechanisms. Full article

This study develops a practical, on-farm methodology for optimizing cotton cultivation through Variable Rate Seeding (VRS), utilizing existing farm data and remote sensing, while minimizing operational interference. The methodology involved an experimental design across five rainfed cotton fields on a Brazilian commercial farm, testing four seeding rates (90%, 100%, 110%, 120%) within grid cells using a 4 × 4 Latin square design. Management zones (MZs) were defined using existing soil clay content and elevation data, augmented by twelve vegetation indices from Sentinel-2 satellite imagery and K-Means clustering. Statistical analysis evaluated plant population density’s effect on cotton yield and its association with MZs. For the 2023/2024 season, results showed no positive yield response to increasing plant density above field averages, with negative responses in many plots (e.g., 84% in Field A), suggesting potential gains from reducing rates. The association between population density effect classes and MZs was highly significant with moderate to relatively strong Cramer’s V values (up to 0.47), indicating MZs effectively distinguished response areas. Lower clay content consistently correlated with yield losses at higher densities. This work empowers farm managers to conduct their own site-specific experimentation for optimal seed populations, enhancing precision agriculture and resource efficiency. Full article

The soil freeze–thaw process is a dominant disturbance in the seasonally frozen ground and the active layer of permafrost, which plays a crucial role in the surface energy balance, water cycle, and carbon exchange and has a pronounced influence on vegetation phenology. This study proposes a novel density-based Freeze–Thaw Disturbance Index (FTDI) based on the identification of the freeze–thaw disturbance region (FTDR) over the Qinghai–Tibet Plateau (QTP). FTDI is defined as an areal density metric based on geomorphic disturbances, i.e., the proportion of FTDRs within a given region, with higher values indicating greater areal densities of disturbance. As a measure of landform clustering, FTDI complements existing freeze–thaw process indicators and provides a means to assess the geomorphic impacts of climate-driven freeze–thaw changes during permafrost degradation. The main conclusions are as follows: the FTDR results that are identified by the random forest model are reliable and highly consistent with ground observations; the FTDRs cover 8.85% of the total area of the QTP, and mainly in the central and eastern regions, characterized by prolonged freezing durations and the average annual ground temperature (MAGT) is close to 0 °C, making the soil in these regions highly susceptible to warming-induced disturbances. Most of the plateau exhibits low or negligible FTDI values. As a geomorphic indicator, FTDI reflects the impact of potential freeze–thaw dynamic phase changes on the surface. Higher FTDI values indicate a greater likelihood of surface thawing processes triggered by rising temperatures, which impact surface processes. Regions with relatively high FTDI values often contain substantial amounts of organic carbon, and may experience delayed vegetation green-up despite general warming trends. This study introduces the FTDI derived from the FTDR as a novel index, offering fresh insights into the study of freeze–thaw processes in the context of climate change. Full article

Excessive nitrogen addition in farmland on the Loess Plateau reduces soil quality and endangers the atmospheric environment. We designed an experiment to investigate the effects of different nitrogen application rates on the soil physicochemical properties and microbial diversity of spring wheat fields on the Loess Plateau, aiming to identify the optimal nitrogen application rate and avoid the detrimental effects of excessive nitrogen addition. A field experiment was conducted from 2022 to 2023 with four nitrogen (N) application rates (0, 55, 110, and 220 kg·N·ha⁻¹·y⁻¹). This study aimed to assess the changes in soil properties, nutrient contents, enzyme activities, and bacterial community structure. The results showed that increasing N application generally enhanced soil bulk density, nitrate nitrogen (NO₃⁻-N), ammonium nitrogen (NH₄⁺-N), and microbial biomass nitrogen (MBN) (p < 0.05). In contrast, soil water content initially increased and then decreased. Soil organic carbon and total nitrogen rose markedly with higher N inputs, particularly in the 0–20 cm layer, whereas total phosphorus was less affected. Nitrogen addition stimulated soil enzyme activities (protease, urease, nitrate reductase, and nitrite reductase), though excessive input (220 kg·N·ha⁻¹·y⁻¹) produced inhibitory effects. Actinobacteria (relative abundance: 29–35%) and Proteobacteria (relative abundance: 14–22%) were the dominant phyla in all treatments. Alpha diversity peaked at low nitrogen input (55 kg·N·ha⁻¹·y⁻¹), while high N level reduced evenness and species richness (p < 0.05). Principle Coordinate Analysis (PCoA) revealed that both N application and soil depth shaped microbial community assembly, with deeper layers (20–40 cm) being more sensitive to N input. Correlation analysis indicated that soil moisture, bulk density, and C:N:P stoichiometry were key drivers of bacterial community variation. Overall, moderate nitrogen input (110 kg·N·ha⁻¹·y⁻¹) improved soil fertility and supported microbial functionality, whereas excessive application degraded soil structure and reduced biodiversity. These findings highlight the need for balanced N management strategies in rain-fed agriculture of the Loess Plateau to sustain both productivity and ecological stability. Full article

Northern artificial forests play a vital role in enhancing carbon sequestration and ecosystem services, yet quantitative evidence on how different management measures affect understory biodiversity and productivity remains limited. This study focused on Larix gmelinii var. principis-rupprechtii (Mayr) Pilg. plantations in Weichang, Hebei Province, and compared three forest management regimes: target-tree management, homogeneous management, and un-managed stands. We systematically examined understory plant diversity indices (Shannon, Simpson, Margalef, Gleason, and Pielou), shrub–herb layer biomass, soil organic carbon (SOC), and total nitrogen (TN), and employed correlation analysis and random forest modeling to identify the main driving factors. Results showed that target-tree management significantly enhanced both understory biodiversity and shrub–herb biomass, followed by homogeneous management, while unmanaged stands had the lowest values. Differences in SOC and TN among treatments were not significant. Stand structural factors were the dominant drivers: stand density and basal area were negatively correlated with diversity and biomass, while community evenness (Pielou) was positively correlated with biomass. Random forest analysis further indicated that basal area and stand density had the highest relative importance, followed by evenness, whereas soil factors contributed less. Mechanistically, target-tree management improved light availability and spatial distribution by reducing stand density, thereby increasing evenness and promoting biomass accumulation. Overall, optimizing stand structure, rather than merely increasing species richness, proved more effective in simultaneously enhancing biodiversity and productivity in light-limited Larix plantations. From a management perspective, target-tree management combined with density regulation and structural optimization is recommended to achieve near-natural management goals and enhance multiple ecological functions. Full article

Atmospheric deposition is considered a source of heavy metals in plants. However, research on the uptake pathways of atmospheric particulate matter by leaves and the subsequent translocation of heavy metals within plants remains limited. In this study, the foliar uptake and translocation of heavy metals in two maize cultivars (fresh corn and silage corn cultivars, called Baiyunuo909 and Qingzhu932, respectively) were investigated through foliar exposure using soil from a mining area to simulate dry deposition under controlled chamber conditions. The height and biomass of maize were inhibited after three and five exposures to fallout deposition, and this inhibitory effect became increasingly pronounced with prolonged exposure. Furthermore, the activities of catalase (CAT) and superoxide dismutase (SOD), along with the malondialdehyde (MDA) content, significantly decreased in both cultivars relative to the control. This decrease was more significant in fresh maize, with the reduction ranges being 94.3%, 42.1%, and 40.8%, respectively. Fallout exposure elevated the contents of cadmium, lead, arsenic and zinc in the leaves, stems, and sheaths of both cultivars, despite no significant increase in the roots. The bioconcentration factors of leaves for heavy metals ranged from 0.0002 to 0.0007, representing a 3.5–fold variation; however, the overall low values showed no significant differences. Scanning electron microscopy with energy-dispersive spectroscopy revealed the accumulation of particulate matter on the leaf surface, with a higher density around the cuticle and stomata. Additionally, the fresh corn cultivar demonstrated greater sensitivity to fallout than the silage corn cultivar. In summary, heavy metals present in atmospheric particulate matter can be absorbed by leaves and subsequently translocated to other plant tissues. This study provides a theoretical foundation for understanding the mechanisms of foliar heavy metal uptake in maize. Full article