Search Results (168)

Nitrogen (N) fertilizer management in winter wheat production faces challenges from volatilization losses and sub-optimal application strategies. This is particularly problematic in the Southern Great Plains, where environmental conditions during top-dressing periods favor N losses. This study evaluated the effects of a fertilizer placement method, enhanced-efficiency fertilizers, and application timing on grain yield and protein concentration (GPC) across six site-years in Oklahoma (2016–2018). Treatments included broadcast applications of untreated urea and SuperU^® (urease/nitrification inhibitor-treated urea). These were compared with subsurface placement using single-disc and double-disc drilling systems, applied at 67 kg N ha⁻¹ during January, February, or March. Subsurface placement increased the grain yield by 324–391 kg ha⁻¹ compared to broadcast applications at sites with favorable soil conditions. However, responses varied significantly across environments. Enhanced-efficiency fertilizers showed limited advantages over untreated urea. Benefits were most pronounced during February applications under conditions favoring volatilization losses. Application timing effects were more consistent for GPC than for the yield. Later applications (February–March) increased GPC by 0.8–1.2% compared to January applications. Treatment efficacy was strongly influenced by soil pH, equipment performance, and post-application environmental conditions. This indicates that N management benefits are highly site-specific. These findings demonstrate that subsurface placement can improve nitrogen use efficiency (NUE) under appropriate conditions. However, success depends on matching application strategies to local soil and environmental factors rather than adopting universal recommendations. Full article

This paper presents field investigations of a corrugated steel soil–steel arch structure with a span of 25.7 m and a rise of 9.0 m—currently the largest single-span structure of its kind in Europe. The structure, serving as a wildlife crossing along the DK16 expressway in northeastern Poland, was constructed using deep corrugated steel plates (500 mm× 237 mm) made from S315MC steel, without additional reinforcements such as stiffening ribs or geosynthetics. The study focused on monitoring the structural behavior during the critical backfilling phase. Displacements and strains were recorded using 34 electro-resistant strain gauges and a geodetic laser system at successive backfill levels, with particular attention to the loading stage at the crown. The measured results were compared with predictions based on the Swedish Design Method (SDM). The SDM equations did not accurately predict internal forces during backfilling. At the crown level, bending moments and axial forces were overestimated by approximately 69% and 152%, respectively. At the final backfill level, the SDM underestimated bending moments by 55% and overestimated axial forces by 90%. These findings highlight limitations of current design standards and emphasize the need for revised analytical models and long-term monitoring of large-span soil–steel structures. Full article

In this study, the efficacy of super white cement (SWC) to improve organic soils was researched. For stabilization, 10%, 15%, and 20% proportions of SWC were added to organic soil. After improvement with SWC, Atterberg limit testing, standard Proctor tests, triaxial compression tests, and swelling and compressibility tests were performed on the organic soil. Proctor tests showed that stabilization of organic soil with SWC increased maximum dry density (MDD) and optimum moisture content (OMC) values. After stabilization, the unconfined compressional strength values of the soil increased. This increase continued until the 28th day and had a reducing trend after improvement with SWC, linked to time. In addition to the reaction between SWC and OS, the time-dependent behavior of OS also contributed to this behavior. With the increase in SWC proportions, the cohesion intercept and internal friction angle values rapidly increased until the 56th day. This increase began to reduce after the 56th day. After stabilization, the swelling percentage and compressibility values for the soil reduced. The addition of SWC within organic soil appeared to improve the engineering properties of the soil. Full article

(1) Background: Wetlands are ecologically significant ecosystems that support biodiversity and contribute to essential environmental functions such as water purification, carbon storage and flood regulation. However, these ecosystems face increasing pressures from land-use change and degradation, prompting the need for scalable and accurate classification methods to support conservation and policy efforts. In this research, our motivation was to test whether high-spatial-resolution PlanetScope imagery can be used with pixel-based machine learning to support the mapping and monitoring of wetlands at a national scale. (2) Methods: This study compared four machine learning classification models—Random Forest (RF), XGBoost (XGB), Histogram-Based Gradient Boosting (HGB) and a Multi-Layer Perceptron Classifier (MLPC)—to detect and map wetland areas across New Zealand. All models were trained using eight-band SuperDove satellite imagery from PlanetScope, with a spatial resolution of ~3 m, and ancillary geospatial datasets representing topography and soil drainage characteristics, each of which is available globally. (3) Results: All four machine learning models performed well in detecting wetlands from SuperDove imagery and environmental covariates, with varying strengths. The highest accuracy was achieved using all eight image bands alongside features created from supporting geospatial data. For binary wetland classification, the highest F1 scores were recorded by XGB (0.73) and RF/HGB (both 0.72) when including all covariates. MLPC also showed competitive performance (wetland F1 score of 0.71), despite its relatively lower spatial consistency. However, each model over-predicts total wetland area at a national level, an issue which was able to be reduced by increasing the classification probability threshold and spatial filtering. (4) Conclusions: The comparative analysis highlights the strengths and trade-offs of RF, XGB, HGB and MLPC models for wetland classification. While all four methods are viable, RF offers some key advantages, including ease of deployment and transferability, positioning it as a promising candidate for scalable, high-resolution wetland monitoring across diverse ecological settings. Further work is required for verification of small-scale wetlands (<~0.5 ha) and the addition of fine-spatial-scale covariates. Full article

With the rapid development of the national economy, the construction of super high-rise buildings, long-span bridges, high-speed railways, and transmission towers has become increasingly common. It is also more frequent to build structures on karst foundations, which imposes higher demands on foundation engineering, especially pile foundations. To study the influence of the roughness factor (RF) on the bearing characteristics of rock-socketed pile, model pile load tests were conducted with different RF values (0.0, 0.1, 0.2, and 0.3) to reveal the failure modes of the test pile, analyze the characteristics of the load–displacement curves and the axial force and resistance exertion law of the pile, and discuss the influence of the RF on the ultimate bearing capacity of the test pile. Based on the load transfer law of test piles, a load transfer model considering the relative pile–soil displacement and the shear dilatancy effect of pile–rock is established to analyze its load transfer characteristics. The results show that the failure mode of the test pile is splitting failure. The load–displacement curves are upward concave and slowly varying. The pile side resistance and the pile tip resistance mainly bear the load on the pile top. As the load on the pile top increases, the pile tip resistance gradually comes into play, and when the ultimate load is reached, the pile tip resistance bears 72.12% to 79.22% of the upper load. The pile side resistance is mainly borne by the rock-socketed section, and the pile side resistance increases sharply after entering the rock layer, but it decreases slightly with increasing depth, and the peak point is located in the range of 1.25D below the soil–rock interface. Increasing the roughness of the pile can greatly improve the ultimate bearing capacity. In this study, the ultimate bearing capacity of the test pile shows a trend of increasing and then decreasing with the gradual increase in RF from 0.0 to 0.3, and the optimal RF is 0.2. The load transfer model of pile–soil relative displacement and pile–rock shear dilatancy effect, as well as the pile tip load calculation model, were established. The calculation results were compared with the test results and engineering measured data, respectively, and they are in good agreement. Full article

Mud-protected bored piles are widely used in foundation engineering due to their high bearing capacity and strong adaptability to various geological conditions. However, the formation of mud skin around the pile shaft and sediment at the pile bottom during construction significantly affects their mechanical behavior, posing challenges for performance evaluation and design optimization. The post-grouting technique, which involves injecting grout material to strengthen the bottom and surrounding soils, has been practically adopted to enhance pile performance. This study investigates the effect of construction-induced factors (mud skin and sediment) and post-grouting on the performance of mud-protected bored piles. Finite element analyses were conducted based on a super-long test pile (60 m in length, 1.8 m in diameter) from an infrastructure project in Eastern China. The numerical model was validated against field test measurements and previously published numerical results. The results reveal that mud skin and sediment individually decrease the bearing capacity by 28% and 24%, respectively, compared to ideal conditions. When both factors are present, the bearing capacity is decreased by 36%. The post-grouting technique effectively improves pile performance, increasing the bearing capacity by 81% compared to non-grouting conditions. The findings also demonstrate that side friction dominates the bearing behavior of the studied super-long pile, accounting for approximately 90% of the total bearing capacity. Parametric analysis indicates that post-grouting effectiveness varies with soil properties and dimensions of effective grouting zones, showing greater improvement in weak soils. These results provide insights into the mechanisms through which construction-induced effects impact pile performance and offer guidelines for post-grouting applications. Full article

To ensure the stability of deep foundation pits in confined aquifers, dewatering is often required. However, pumping from confined aquifers in large deep foundation pit groups may lead to significant environmental deformations. Therefore, field pumping and recharge tests are required to guide design of groundwater and environmental deformation control scheme. Focusing on a super-large deep foundation pit group in Shanghai, single-well pumping, multi-well pumping, and recharge tests were conducted in distinct geological zones (normally consolidated area and paleochannel zone). The hydraulic connectivity and spatiotemporal patterns of groundwater drawdown and soil settlement were systematically analyzed. The results show that: (1) There exists a certain hydraulic connection between the first and second confined aquifers. In the paleochannel area, the aquitard between the micro-confined and the first confined aquifer is insufficient to completely block hydraulic connectivity. (2) The ratio of ground surface settlement to groundwater drawdown is about 3.4 mm/m, and the deep soil settlement is significantly or even greater than the surface settlement, so it is necessary to strengthen the monitoring of deep settlement. (3) Recharge can elevate the groundwater and reduce settlement; however, it is difficult to eliminate the variation in settlement along the vertical direction. Full article

The joint of a shield tunnel segment is the weak part of tunnel, and the opening amount of the joint seriously affects the watertightness of the internal structure of the tunnel. In this experiment, a model was created with ANSYS, the fluid–solid coupling effect of the seawater and seabed was considered using the SuperFLUSH/2D 6.0 software, and the local site effect was considered by free-field seismic response analysis. Considering the structure and stress characteristics of the shield tunnel in conjunction with the marine area, earthquake research on shield tunnel culverts was conducted using lateral and longitudinal beam–spring models. The main focus of this article is to study the earthquake resistance of shield tunnel joints under extreme seismic excitation (SL-2) in complex marine environments. The results indicated that in the lateral analysis, under varying soil layer conditions, the diameter deformation rates for sections 1 and 2 using high-strength bolts were 1.752% and 1.334%, respectively, while the joint-opening amounts were 0.515 mm and 0.387 mm, respectively. This suggests that locations with thicker silt layers exhibit larger joint-opening amounts and are more susceptible to deformation. In the longitudinal analysis, when bolt strength varied, the maximum joint-opening ranged from 4.706 mm to 6.507 mm, and the maximum dislocation ranged from 0.625 mm to 1.326 mm. The deformation rule of the joint bolts followed the pattern that higher stiffness led to smaller deformation, whereas poorer geological conditions resulted in larger deformation. Therefore, the interface between soft and hard strata is a weak point in the longitudinal seismic resistance of the shield tunnel structure. The conclusions of this study can supplement the seismic research on shield tunnels in the marine areas of nuclear power plants. Full article

The super high-density (SHD) production system has recently been introduced to the Chilean European plum (Prunus domestica L.) industry, but the potential of applying regulated deficit irrigation (RDI) in this system remains unexplored. As irrigation water availability in Chile has been strongly jeopardized by climate change, there is an urgent need to validate water-conserving practices in modern production systems. A field study was conducted in a commercial SHD European plum orchard (cv. French grafted on Rootpac-20 rootstock) for two consecutive seasons in Peralillo, O’Higgins Region, Chile. The objective of this study was to assess the impact of a late water deficit (LD) on water productivity, fruit quality, plant water relations, and soil microbiota. The results showed that implementing LD enhanced water productivity by 40% without compromising fresh and dry fruit quality. Moderate to severe water stress induced no changes in physiological parameters such as stomatal conductance and photochemical efficiency. Additionally, the LD treatment significantly reduced soil moisture but increased the abundance of certain groups of beneficial soil microbiota and fine roots. These results highlight the potential of LD as a viable water-conserving practice in modern SHD European plum orchards, particularly in regions facing water scarcity due to climate change. Full article

In order to meet the demand for coordinated development of agricultural waste utilization and water-saving agriculture, this study utilized waste celery tailings (CT) to make a super-absorbent hydrogel by chemical cross-linking. The hydrogel was optimized and screened. The study demonstrated the optimal CT-gel synthesis method: 7.5 wt% CT, 0.05 wt% MBA cross-linker, and 70 °C for 2 h. The optimized gel had a water absorption of 708 g/g and a water retention of more than 20% at 25 °C on day 10. The soil water retention of the CT-gel increased with time and dosage. In sandy soils, 0.6% CT-gel was most effective. The pot experiment showed that 2% of the gel significantly increased the height and growth rate of radish seedlings. This study effectively utilized various components of CT and provided a scalable approach for converting agricultural waste into functional materials, which is valuable for arid soil improvement and sustainable agriculture. Full article

To the aim of this paper is to study the structural and environmental deformation characteristics caused by the excavation of a very large deep foundation pit in the sandy soil area of Beijing. This paper is based on numerical simulation and field monitoring results and these results are compared with the deformation data of a soft soil foundation pit in the Shanghai area. The results show that the influence of the environment surrounding the super-large deep foundation pit project studied in this paper is obviously too great. With the progress of construction, the deformation rate and deformation amount of the column at the side of the foundation pit are obviously higher than that of the column in the middle area. Due to the “hysteresis” of stress transfer in the sand, the settlement of the roof of the north wall is delayed and the deformation range is smaller than that of the south wall. Compared with the conventional foundation pit, the influence area of the surrounding surface is larger, reaching 4 He (He is the depth of the foundation pit). Δvmax (the maximum surface settlement) is between 0.2~2.3% He, and the relationship between δvmax = 1.43% Vwm. Through orthogonal experiments and numerical simulation, it is concluded that the deformation of foundation pit structure and its surrounding environment is more sensitive to excavation unloading, precipitation amplitude, and column spacing. It is also concluded that the strong, medium, and weak influence areas of the bottom uplift after foundation pit construction are (0~0.07) × L, (0.07~0.14) × L, and (0.14~0.5) × L, respectively (L is the width of foundation pit). When the embedment ratio is between 1.8~2.4, the displacement mode of the parapet structure is T mode; when the embedment ratio is between 2.4~3.4, the displacement mode of the parapet structure is RB mode. Full article

The Upper Cikeruh Sub-watershed, part of the Citarum Basin and designated as one of Indonesia’s 15 Super Priority Watersheds, is facing severe degradation due to land use changes and deforestation, particularly in the upstream areas. This study assesses land criticality and suitability for agroforestry to guide sustainable land management practices. A semi-quantitative approach was used to evaluate land criticality through a scoring method, while qualitative match table analysis determined land suitability for specific agroforestry crops. Fieldwork was conducted in the upstream areas of the Cikeruh Sub-watershed, covering the administrative areas of Bandung and Sumedang. The results showed that most areas showed critical land conditions, with productivity identified as the most limiting factor, with scores as low as 30. The agroforestry suitability analysis showed that specific land mapping units (LMUs A, C, D, E, F, and N) were marginally suitable (S3) for crops such as legumes, upland rice, corn, soybeans, and chilies, with the main constraints being slope steepness and soil pH. This study highlights the urgent need to implement agroforestry practices as a restoration strategy in degraded landscapes. The findings provide actionable recommendations to improve land productivity while promoting sustainable watershed management in one of Indonesia’s critical areas. Full article

The increasing frequency of extreme climate events has posed severe challenges to China’s socio-economic development and ecological environment due to geological disasters. Therefore, there is an urgent need for effective adaptive strategies to enhance geo-disaster resilience. Environmental governance, as an effective measure to reduce risks from extreme climates and disasters while promoting high-quality social development, remains underexplored in terms of its impact on geo-disaster resilience. This study innovatively constructs a resilience assessment framework that considers extreme climate and geo-disaster intensity, integrating various statistical methods, including the Super-Efficiency Slacks-Based Measure Data Envelopment Analysis (SBM-DEA) model, spatial Markov chains, and methods such as Geodetector and the Geographically and Temporally Weighted Regression (GTWR), to reveal the spatiotemporal evolution of geo-disaster resilience in China from 2007 to 2022, while also analyzing the mechanisms through which environmental governance influences resilience and its spatiotemporal variations. The findings indicate that China’s geo-disaster resilience exhibits unstable growth with significant regional disparities. Spatially, resilience shows notable spillover effects and a tendency toward convergence within similar regions. Environmental governance unevenly enhances resilience over time and space: soil and water conservation and afforestation are generally effective measures, while the contributions of ecological water replenishment, environmental facility management personnel, fiscal expenditure, and nature reserve protection vary by region. This research offers key insights into improving geo-disaster resilience and optimizing environmental governance strategies to enhance China’s disaster response capacity and regional sustainable development. Full article

Investigating the variation in and key factors influencing the yield of super hybrid rice cultivated at different altitudes but within the same latitude provides valuable insights for further improvements in super hybrid rice grain yields. Field and pot experiments were conducted using four rice varieties at the following two altitudinal locations in Sichuan Province, China: Hanyuan (high, 1000 m) and Luxian (low, 300 m). The results indicated that Hanyuan achieved an average grain yield of 13.89 t ha⁻¹ in paddy fields, with yields being from 63.6% to 94.2% higher than those at Luxian in the field experiments and from 10.8% to 68.0% higher in the pot experiments. The grain yield was consistently higher in the soil from Hanyuan compared to that from Luxian at the same sites. In the field experiments, the grain yield was influenced by location (L), plant density (P), and variety (V), but there were no significant interactions between these factors. In the pot experiments, the grain yield was significantly impacted by L, soil (S), and the interaction between L and S. Climatic factors, which varied with the altitude of the planting site, played a crucial role in achieving optimal yields of the super hybrid rice. Hanyuan exhibited more cumulative solar radiation with a longer growth duration and lower temperatures and higher soil fertility compared to Luxian. The higher grain yield observed at Hanyuan was linked to increases in panicle numbers, spikelets per panicle, grain filling, pre- and post-heading biomass production, and the harvest index. The variations in biomass production between Hanyuan and Luxian were largely due to differences in pre- and post-heading crop growth rates (CGRs) and pre-heading radiation use efficiency (RUE), which were influenced by differences in the maximum and minimum temperatures and cumulative solar radiation. This study indicated that the differences in the grain yield of super hybrid rice across various ecological sites are primarily influenced by altitude and soil fertility, and further enhancement of the grain yield can be achieved by concurrently increasing biomass production before and after heading through improvements in pre- and post-heading CGR. Full article

Accurate digital soil organic carbon mapping is of great significance for regulating the global carbon cycle and addressing climate change. With the advent of the remote sensing big data era, multi-source and multi-temporal remote sensing techniques have been extensively applied in Earth observation. However, how to fully mine multi-source remote sensing time-series data for high-accuracy digital SOC mapping remains a key challenge. To address this challenge, this study introduced a new idea for mining multi-source remote sensing time-series data. We used 413 topsoil organic carbon samples from southern Xinjiang, China, as an example. By mining multi-source (Sentinel-1/2) remote sensing time-series data from 2017 to 2023, we revealed the temporal variation pattern of the correlation between Sentinel-1/2 time-series data and SOC, thereby identifying the optimal time window for monitoring SOC using Sentinel-1/2 data. By integrating environmental covariates and a super ensemble model, we achieved high-accuracy mapping of SOC in Southern Xinjiang, China. The results showed the following aspects: (1) The optimal time windows for monitoring SOC using Sentinel-1/2 data were July–September and July–August, respectively; (2) the modeling accuracy using multi-source sensor data integrated with environmental covariates was superior to using single-source sensor data integrated with environmental covariates alone. In the optimal model based on multi-source data, the cumulative contribution rate of Sentinel-2 data is 51.71% higher than that of Sentinel-1 data; (3) the stacking super ensemble model’s predictive performance outperformed the weight average and simple average ensemble models. Therefore, mining the optimal time windows of multi-source remote sensing data and environmental covariates, driven a super ensemble model, represents a high-accuracy strategy for digital SOC mapping. Full article