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The self-healing capacities of a GCL with natural bentonite (NB) as core (NB-GCL) and a GCL with a polymerized bentonite (PB) as core (PB-GCL) were investigated under simulated field conditions, i.e. geomembrane-GCL-a clayey subsoil layer composite liner system with a damage hole on the geomembrane and the GCL. The clayey subsoils tested had initial water contents of 22.2% and 26.8%. The liquids used were deionized (DI) water and 0.3 M NaCl solution. The test results indicate that for both the PB-GCL and NB-GCL only hydrated on the subsoils for 1–3 months, a damage hole of 15 mm in diameter was almost not self-healed. For cases of applying a constant liquid head on the top of the geomembrane of 100 mm, the sizes of damage holes were self-healed in term of diameter is about half of the values reported in the literature for tests with plenty liquid supply to the damaged GCLs. Further, for the conditions tested and for the cases self-healed, DI water leaked into the subsoil was less than about 60 g, and 0.3 M NaCl solution leaked was less than 150 g. • Self-healing capacity of GCLs was newly studied under a simulated field condition. • GCLs hydrated on clayey subsoils had very limited self-healing capacity. • Self-heling capacity of GCLs with limited liquid supply was clarified. • Leakage through a hole on GCL before it was self-healed was novelly investigated. [ABSTRACT FROM AUTHOR]

The effect of vertical vibrational loads on the bearing capacity of a foundation resting on salt-encrusted flat soil improved by cement addition was experimentally examined by conducting a physical model. The vibration foundation model resting on the finite dimensions of cemented sabkha was first subjected to incremental vertical monotonic loads to evaluate the bearing capacity for different subsoil conditions; the bearing capacity was calculated from the load–settlement curves. The cemented sabkha overlies the saturated sabkha soil. The influence of the vertical vibrational load for each increment in the vertical monotonic load on the settlement was studied, and a modified load–settlement curve was introduced. For a foundation with no large deformation or liquefaction due to vibrational loads, the vibrational loads insignificantly influence the bearing capacity of the foundation. With increasing frequency, the initial stiffness decreases, resulting in an increase in the settlement. The influence of the cement content and thickness of cemented sabkha on decreasing the foundation's settlement decrease with increasing monotonic loads and operating frequency. [ABSTRACT FROM AUTHOR]

• The original design of the plow-subsoiler-fertilizer. • Deep loosener combined with a reversible plow. • Soil fertilization is combined with the process of its cultivation. • Vibratory subsoiler reduces drag force. • Calculated optimal design parameters. The use of intensive technologies for the cultivation of agricultural crops provides for the application of fertilizers in the process of tillage. This reduces the compaction of the soil, increases its fertility and the quality of the crop. The purpose of these studies is to develop a universal working tool that allows you to combine several technological operations in one pass of the unit. The authors have developed an original design of a plow-subsoiler-fertilizer. This combined working body includes a reversible plow and a vibratory subsoiler with fertilizer ducts. This solution allows you to combine the application of fertilizers when plowing the field, loosening the subsoil layer and mixing the soil. As a result of the work, the dependences of the geometric dimensions of the structure on the traction resistance to movement in the soil were obtained. To implement the developed idea into a real design, the main parameters of the plow-subsoiler-fertilizer are determined. Particular attention is paid to the calculation of the spring mechanism that ensures the vibration of the subsoiler. The optimal number and location of belleville springs in the block and shock absorber were selected, at which the subsoiler will perform self-oscillations with a given amplitude. [ABSTRACT FROM AUTHOR]

This paper investigated effects of geogrid reinforcement on the load transfer in pile-supported embankment under cyclic loading using self-moving trapdoor tests. In the self-moving trapdoor test setup, the trapdoor between two stationary portions (which were equivalent to the piles) was supported by compression springs to simulate the subsoil. Quartz sand and a biaxial geogrid were used as the test fill and reinforcement material, respectively. Tests results show that soil arching above the geogrid reinforcement and load transfer to the stationary portions (caused by the soil arching and tensioned membrane effect) experienced a process of "relatively enhancing - relatively degrading" with an increase in the number of cycles and maintained similar degrees within each complete cycle of cyclic loading. Moreover, the inclusion of geogrid reinforcement reduced the mobilization of soil arching, but increased the degree of load transfer to the stationary portions. In addition, cyclic loading with a higher frequency tended to mobilize more soil arching and induce a higher degree of load transfer to stationary portions. Also observed was that a higher frequency cyclic loading tended to decelerate the degradation of load transfer to stationary portions and caused less surface settlement, which indicating increased load-carrying capacity of pile-supported embankment. • Paper highlights the load transfer in geosynthetic-reinforced pile-supported embankment under cyclic loading. • The effects of number of cycles on the soil arching and load transfer to piles are evaluated. • Effect of geogrid reinforcement on the load transfer in pile-supported embankment is investigated. • The load transfer characteristics of cyclic loading with different frequencies are compared and discussed. [ABSTRACT FROM AUTHOR]

The stress conditions of geosynthetic reinforcements (GRs) are crucial in achieving the accurate serviceability design of geosynthetic-reinforced pile-supported (GRPS) embankments. However, the sensitivity of load distribution to the settlement process has been reported in geosynthetic-reinforced embankment overlying cavities. In this study, a three-dimensional model embankment was used to perform experiments and evaluate the load acting on the GR. A flexible pressure-mapping sensor was introduced to investigate the pressure distribution for two types of supporting conditions: partitioned displacement by multiple movable trapdoors and even trapdoor settlement underneath different subsoil materials. The results showed that the load on the GR was concentrated on the strip areas between adjacent pile heads along with the settlement. The measured load on the GR strip area was related to the settlement process and finally exhibited a U-shaped distribution after detachment from the support underneath. The soil arch height in the subgrade continuously increased with the settlement; meanwhile, the pile head load increased rapidly at first and then decreased slightly or remained stable depending on the foundation support stiffness. For both types of settlement behaviours, soil arching exhibited stress history-related characteristics that influence the load transfer in GRPS embankments. • A model test is designed to evaluate the reinforcement load in geosynthetic-reinforced pile-supported embankments. • The sensitivity of load distribution to the foundation settlement process is investigated. • The stress history-related characteristics of the load distribution and soil arching are revealed. [ABSTRACT FROM AUTHOR]

A simplified method for assessing the serviceability performance of geosynthetic reinforced and pile-supported embankment is presented, where the subsoil consolidation is introduced remaining compatible with the development of soil arching and the reinforcement sag. A piecewise function of the ground reaction curve is developed and used to quantify the arching efficiency. The link between the arching evolution and the subsoil consolidation is then established through the load-carrying equilibrium in the area between piles together with the tensile membrane theory. The reaction of the subsoil is described using the 1-D consolidation theory where the stress history is considered. A parametric study is performed to demonstrate the serviceability performance of a geosynthetic reinforced and pile-supported embankment. The serviceability design of the geosynthetic reinforced and pile-supported embankment is achieved with the proposed method which offers an approach to estimate the time consumed and the subsoil settlement required to achieve a service state. • A simple method is proposed for assessing the serviceability performance of the GRPS embankment. • The evolution of soil arching remains compatible with the development of subsoil settlement and reinforcement sag. • A piecewise function of GRC is newly defined and adopted in the method to quantify arching efficiency. • The parametric study was performed and the serviceability performance of a GRPS embankment is assessed. • The method is capable of determining the time consumed and the subsoil settlement required to achieve a service state. [ABSTRACT FROM AUTHOR]

Subsurface manure application has been suggested as a priming strategy to improve soil fertility and potentially enhance crop yield quickly. However, the soil quality and ecosystem multifunctionality responses and their relationship with crop yield remain uncertain. Here, a two-year field experiment was conducted to investigate the effects of different subsurface manure application methods (1T, one-time fertilization; and 2T, two-time split fertilization during two consecutive years) with the same manure amount on soil quality index (SQI), ecosystem multifunctionality (EMF), and crop yield in the North China Plain. Compared to control (no manure application, CK), 1T increased SQI at both 0–20 and 20–40 cm soil layers by 15–19 % in the first year, but no change in the second year. As a comparison, 2T increased SQI at 0–20 and 20–40 cm soils by 37–42 % compared to CK in the second year. Meanwhile, 2T increased soil EMF at 0–20 cm (0.4 unit) compared to CK over the two years. Both 1T and 2T increased soil EMF at 20–40 cm (0.1–0.8 unit) over the two years. The crop yield was positively related to surface SQI and subsurface EMF regardless of manure application method. Soil organic C, total C, total N, total P, and the C and P cycling-related enzyme activities were key factors that contributed to the improvement of SQI and EMF. The partial least squares path models revealed that the two subsurface manure application methods enhanced surface SQI and subsurface EMF by improving topsoil nutrients and subsoil enzyme activities separately, consequently increasing crop yield. Overall, our results documented that subsurface manure application is an effective strategy for improving soil quality and crop yield. [Display omitted] • The effects of two subsurface manure application methods were explored in the North China Plain. • One-time application increased soil ecosystem multifunctionality compared to control at 20–40 cm. • Two-time split application enhanced soil quality index and ecosystem multifunctionality at 0–20 cm and 20–40 cm. • The improved topsoil quality and subsoil multifunctionality contributed to increased winter wheat yield. [ABSTRACT FROM AUTHOR]

• The S2CPL model can segment and extract growth features of green asparagus infield. • Lightweight convolution and attention mechanism are introduced to improve YOLO v8. • A 3D morphology extraction method is proposed for length-diameter calculation. • Harvest evaluation and subsoil 3D Cutting-Point location are achieved for elective harvesting. • Camera pose optimization is carried out during recognition tests. Robotic selective harvesting is an ideal method for bionic manual harvest of green asparagus. However, the harvesting robot encounters difficulties in evaluating the suitable harvest due to the tilt and bending of the long stem, as well as determining the precise location of the subsoil cutting-point to prevent damage from bacteria on the cutting surface. This paper proposed the S2CPL model to address the challenges of the harvest evaluation and 3D localization of subsoil cutting-point for selective harvesting of green asparagus in field conditions. Firstly, an RGB-D sensor was used to acquire images and depth information of green asparaguses. Secondly, the improved YOLOv8 by introduced lightweight convolution and attention mechanisms in the feature fusion module to enhance the segmentation accuracy. Thirdly, a 3D morphology extraction method was proposed to calculate the length and diameter of green asparagus by utilizing the image mask fusion with depth information. Finally, harvest evaluation and subsoil 3D cutting-point location were achieved for robotic selective harvesting. In addition, the RGB-D sensor posture was optimized. The test results showed that the Intersection over Union (IoU) of green asparagus segmentation with S2CPL reaches 98.0 %, which outperforms YOLOv5 + uNet, YOLOv7 + uNet and YOLOv8-tiny by 5.60 %, 4.59 % and 1.34 % respectively. The average detection time per image was only 2.0 ms, and the GFLOPS was improved by 23.90 %, 88.49 % and 7.63 % compared with other models. The relative error of the length and diameter were less than 2.98 % and 2.15 %, respectively. The accuracy of location the subsoil cutting-point is more than 99.0 %, and the horizontal positioning error and depth positioning error of cutting-points were less than 6.0 mm and 7.4 mm. The proposed model is of strong robustness even dealing with partial occlusion and motion blur and is suitable with limited computing power to meet the needs of Robotic selective harvesting. [ABSTRACT FROM AUTHOR]

Subsoils contain more than half of global soil organic matter (SOM) stocks. Given that sequestration and turnover processes of SOM are slower in the subsoil than in the topsoil, subsoil carbon (C) stocks are likely to be vulnerable to shifts in precipitation patterns. Therefore, we investigated the responses of different sources of tropical forest soil organic C (SOC) pools to a delayed onset and increased intensity of seasonal precipitation in a 10-year rainfall manipulation experiment. While total SOC varied with soil depth, regardless of shifts in rainfall pattern, we observed that changes in precipitation patterns affected the composition of SOC pools. A delayed wet season increased both the content and proportion of the light fraction C in the SOC at the 0–10 cm depth, potentially due to a decrease in the light fraction decomposition. The delayed wet season also led to a higher content of iron (Fe)-bound organic C, due to impacts on free iron (Fe3+) and aluminum oxides. In addition, wetter wet season led to a higher content of lignin phenols in the top- and subsoil (0–70 cm), due to anoxic conditions preventing lignin decomposition. However, this precipitation shift decreased both the content and proportion of fungal necromass in the SOC in the subsoil (50–70 cm), this was attributed to fungal necromass decomposition by microorganisms facilitated by increased N-acquisition enzyme activity. Overall, greater precipitation intensity increased the vulnerability of subsoil C to losses, primarily due to greater microbial decomposition under increased N limitation. Our study demonstrates the subsoil C-cycling processes in shaping SOM stocks to global changes in precipitation patterns. • Delayed wet season led to higher content of Fe-bound organic carbon in topsoil. • Wetter wet season led to greater content of lignin phenols in soil. • Wetter wet season lead to higher subsoil vulnerability by fungal necromass lost. • Consider subsoil when assessing the impacts of rainfall changes on soil organic matter pools. [ABSTRACT FROM AUTHOR]

In dryland ecosystems, typically characterized by sparse vegetation and nutrient scarcity, pioneer plants exert a critical role in the build-up of soil carbon (C). Continuous root-derived C inputs, including rhizodeposition and structural root litter, create hotspots of increased microbial activity and nutrient availability where biogeochemical processes, such as soil aggregation and the accumulation and stabilization of organic matter (OM), are promoted. Our study aims to disentangle the effects of root C inputs on soil aggregate formation, microbial community structures, and on the fate of OM—both before and after plant death, i.e., during the transition from rhizosphere to detritusphere. This was realized in a two-phase incubation approach, tracing the natural and undisturbed transition from growth to subsequent decomposition of a pioneer plant-root system (Helenium aromaticum) in a semi-arid topsoil and subsoil. We quantified water-stable aggregates, investigated the fate and composition of OM separated into particulate and mineral-associated OM fractions (POM and MAOM), and observed successional changes in the root-associated microbiome. Our results underscore the significance of roots as vectors for macroaggregation within the rhizosphere in both topsoil and subsoil, associated with a particularly strong increase in fungal abundance in the subsoil. In topsoil, we identified root legacy effects in the detritusphere, as root-induced macroaggregation persisted after plant death, a phenomenon not observed in subsoil. These root legacy effects were accompanied by a clear succession towards gram + bacteria, which appeared to outcompete fungi during root decomposition. The increased availability of decaying litter surfaces further facilitated the protection of particulate OM via the occlusion into aggregates. Overall, to gain a holistic understanding of plant-microbe-soil interactions, we emphasize the need for more studies that span over the full temporal dimension from living to dying plants in intact soil systems. [Display omitted] • Macroaggregation increases within the rhizosphere in both topsoil and subsoil. • Fungal hyphae constitute important vectors driving soil aggregation in subsoils. • Root legacy imprinted by persisting aggregates around decaying roots in topsoil. • Root-induced aggregation not persistent after plant death in subsoil detritusphere. • Root litter facilitates the occlusion of POM into aggregates in the topsoil detritusphere. [ABSTRACT FROM AUTHOR]

Subsoil contains a significant amount of soil organic carbon (SOC) in rice paddies, playing a crucial role in global carbon (C) cycling. However, the mechanisms driving SOC dynamics in topsoil and subsoil remain elusive, as the vertical distribution of soil microbes and their associated functions varies. In our study, we explored the linkages between SOC dynamics and microbial functions across different soil depths (0–10 cm for topsoil, and 10–20 and 20–30 cm for subsoil) within a framework of contrasting tillage managements, including conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). In the topsoil, bacterial biosynthesis and degradation functions negatively contributed (P < 0.05) to SOC accumulation, whereas in the subsoil layers, these functions exhibited a positive effect. Notably, both partial least squares path modeling (PLSPM) and stepwise regression showed that bacterial biosynthesis and degradation functions exert a stronger influence on SOC accumulation than fungal functions. Metagenomic sequencing revealed that the cellulose degradation (K01179) and reductive tricarboxylic acid cycle (rTCA cycle) (K00174 and K00175) were main factors driving SOC variation in topsoil. Starch degradation (K00705 and K01187) and rTCA cycle (K00175 and K00031) contributed to 93 % of the SOC variation in subsoil. Therefore, the rTCA cycle contributed to SOC variation in paddy soil across 0–30 cm soil profile. Moreover, tillage management could influence the abundances of enzymes associated with starch degradation and rTCA cycle. The contrasting driving factors influencing SOC in topsoil and subsoil could be associated with soil microbial functions, which would response differently to tillage managements. • Soil depth significantly influences SOC, TN, and pH levels more than tillage practices. • Bacterial biosynthesis and degradation functions are found to negatively impact SOC accumulation in the topsoil, whereas they positively affect SOC in subsoil layers. • The reductive tricarboxylic acid cycle is a pivotal driver of SOC variation. • Fungal degradation functions positively contribute to SOC across all soil depths. [ABSTRACT FROM AUTHOR]

• In the A horizon, OC in all fractions was lower in arable than in prairie soils. • OC loss in arable topsoils was mainly driven by losses in mineral-associated OC. • Mineral-associated OC of prairie topsoils correlated most strongly with mineral characteristics. • In the C horizon, water-extractable OC was higher in prairie than in arable soils. Improved understanding of land use derived changes in soil organic matter (OM) compartments stabilized to different degrees against microbial decomposition is required for outlining efficient land use strategies aimed at improving soil ecosystem functions that are strongly coupled to gains and losses of soil organic carbon (OC). However, such data is scarce, particularly in subsoil environments. Consequently, in this study, we analyzed OC storage in topsoils and subsoils, as well as OM fractions with different OC turnover dynamics, including particulate (free and occluded), water-extractable, and mineral-associated OM. We sampled soils under native prairie (10 sites) and long-term arable use (> 40 years, 10 sites) to a depth of 3 m in the central U.S. Our results showed that the arable bulk soils had significantly lower OC content in the A horizon and across all analyzed OM fractions compared to native prairie soils. This reduction was primarily derived from OC losses in the mineral-associated OM (arable: 7.2 ± 0.5 g kg−1; native prairie: 12 ± 0.7 g kg−1), which retained the most significant portion (50–56 %) of bulk soil OC among all fractions. No significant impact of land use on OC storage in the bulk soil and fractions was observed in the subsoil B and C horizons, except for water-extractable OM, which had lower amounts in arable soils in the C horizon than native prairie soils. This underscores the relevance of this fraction for the translocation of OC across the soil profile in undisturbed systems. Our results highlight the crucial role of mineral-associated OM for soil OC storage, but also its sensitivity to land use change, especially in the topsoil, suggesting this fraction is highly relevant for strategies aiming at restoring pre-disturbance soil OC levels. [ABSTRACT FROM AUTHOR]

Nitrogen availability often limits plant growth in forest ecosystems. Plants, including trees, utilize soil inorganic nitrogen transformed via nitrogen cycling processes, including mineralization and nitrification. While most plant fine roots are distributed in surface soil layers, plants take up nitrogen even from subsurface soil layers in addition to the surface soil layers, especially under high nutrient competition. However, there is still limited knowledge about nitrogen cycles within deeper soil layers. In this study, we investigated the vertical profiles (0–60 cm) of the net nitrogen mineralization and nitrification rates at four Japanese forest sites with two different soil types (Andosols and Cambisols). The partial least square path modeling (PLS-PM) was used to determine factors affecting nitrogen cycling processes. The net nitrogen mineralization and nitrification rates per unit soil weight were considerably higher in the surface soil layer than in the deeper soil layers in Andosols but not in Cambisols. PLS-PM analysis showed that microbial biomass and soil organic matter quantities were the important factors influencing the net nitrogen mineralization and nitrification rates, indicating that a similar mechanism, which drives the spatial variations of nitrogen cycling processes in the surface soil layer, predominantly regulates the vertical variations of the processes. Moreover, it was estimated that the net nitrogen mineralization rate could be comparable at all soil types and depths when the rate was expressed per unit soil volume. Therefore, subsoil layers could be a quantitatively important source of plant-available nitrogen in Andosols and Cambisols. • Microbial biomass regulated vertical shifts in net N mineralization per unit weight • Net N mineralization per unit weight decreased with increasing soil depth in Andosols • Net N mineralization per unit volume was vertically consistent in both soil types [ABSTRACT FROM AUTHOR]

The reuse of wastewater (WW) for crop irrigation is increasingly recognized as an alternative to freshwater irrigation in arid and semi-arid regions. However, there is a significant gap in knowledge regarding the soil health index (SHI) and factors influencing topsoil and subsoil in cropland under long-term WW irrigation. This study aimed to comparatively assess soil health attributes between topsoil and subsoil in smallholder farmlands that have been irrigated with WW for over 50 years. This assessment utilized a combination of soil physico-chemical and fertility attributes, along with heavy metal concentrations. The soil health index (SHI) was developed using linear (SHI - L) and nonlinear (SHI - NL) models, based on the Total Data Set (TDS) and Minimum Data Set (MDS). Statistically significant differences (P ≤ 0.05) were observed between topsoil and subsoil for the soil stability index (SSI), organic matter (SOM), calcium carbonate equivalent (CCE), electrical conductivity (EC), sodium adsorption ratio (SAR), macro- and micronutrients, and heavy metals (Zn, Cu, Cd, Pb, and Ni). In contrast, soil bulk density (BD), pH, and cation exchange capacity (CEC) did not show significant differences. The mean SHI - L and SHI - NL values ranged from 0.68 to 0.77 and 0.46–0.53 for topsoil, and from 0.66 to 0.74 and 0.45–0.51 for subsoil, respectively. The SHI values were higher in the topsoil, with increases ranging from 2.3 % to 7.1 % for SHI - L and 0.65–11.3 % for SHI - NL compared to the subsoil. The regression coefficients between SHIs and corn yield were higher in the topsoil (0.46–0.49) than in the subsoil (0.20–0.22). Furthermore, the SHI - NL model demonstrated greater precision than the SHI - L model in predicting corn yield in both soil depths. These findings highlight the effectiveness of SHI assessments, particularly the SHI - NL model, in analyzing changes in soil health indices with depth and their relationship with crop performance in long-term WW-irrigated smallholder farmlands. This research provides valuable insights into addressing soil health challenges in similar agricultural systems. • The changes of soil health index (SHI) with depth was assessed in the cropland under wastewater (WW) irrigation. • Soil organic matter, Cd, and SAR were major factors influencing on SHIs changes in the top- and sub-soils. • SHIs were higher (0.65 – 11.3 %) in the topsoil rather than the subsoil. • The relationship between SHIs and corn yield was more robust in the topsoil than in the subsoil. • Nonlinear-SHI approach was more precise better than linear-SHI approach to evaluate soil health. [ABSTRACT FROM AUTHOR]

Cotton stubble return and subsoiling significantly enhanced soil fertility and cotton yield in coastal saline soils. Despite these benefits, the mechanisms influencing soil organic carbon (SOC) sequestration remain poorly understood. To address this gap, a comprehensive ten-year study was undertaken, focusing on the effects of stubble management (either removal or return) and tillage (either non-subsoiling or subsoiling) on the physicochemical properties of both topsoil (0–20 cm) and subsoil (20–40 cm) layers, as well as on cotton yield. The objectives were to (i) quantify interannual variability (2013–2022), stubble return, and subsoiling on the soil physicochemical properties of the topsoil (0–20 cm) and subsoil (20–40 cm) and cotton yield and (ii) elucidate the mechanism by which these agricultural practices affect SOC sequestration. Findings from this decade-long investigation indicated that ten consecutive years of cotton stubble return and subsoiling at three-year intervals significantly ameliorated soil conditions by reducing the salt content, pH, and the proportion of silt plus clay, while increasing macro-aggregates, mean weight diameter (MWD), aggregates organic carbon (AOC) across various particle sizes, SOC, total nitrogen (TN) in both soil layers, and ultimately, the cotton lint yield. Interestingly, the effect of stubble return on micro-aggregates varied between the two soil layers, leading to a reduction in micro-aggregates by 11.16% in the topsoil, in contrast to a 5.7% increase in the subsoil, when compared to conditions where stubble was removed. The partial least squares path modeling (PLS-PM) indicated that the enhancements in MWD attributable to stubble return and subsoiling were primarily due to significant reductions in soil pH and salt content in both layers, which in turn fostered an increase in AOC, ultimately contributing to higher SOC levels. However, the pathways through which AOC influenced SOC varied significantly between the topsoil and subsoil, with stubble return and subsoiling increasing SOC through an increase in the macro-AOC in the topsoil, and micro-AOC in the subsoil. In summary, long-term cotton stubble return and subsoiling significantly optimize the aggregate particle size distribution and enhance the carbon sequestration potential in coastal saline cotton fields. • Long-term stubble return and subsoiling are effective ways to increase cotton yield. • Cotton stubble return and subsoiling reduce soil pH and salt content. • Stubble return and subsoiling improve the proportion of macro-aggregate. • Stubble return and subsoiling improve SOC by enhancing macro and micro aggregate OC. • The effect of stubble return on microaggregate is opposite in topsoil and subsoil. [ABSTRACT FROM AUTHOR]

A laboratory investigation on the hydration behavior of GCLs from lateritic soils was conducted under isothermal and thermal conditions (tropical climate), varying subsoil moisture contents, GCLs bentonite particle size and mineralogy. GCL hydration levels from lateritic subsoils under isothermal conditions (55%) were similar to literature findings. A slight decrease in water content of some GCLs after long periods of contact with the lateritic soils indicates that equilibrium can demand long time in these soils. GCL with granular bentonites were less efficient to hydrate from lateritic subsoils. GCLs with activated-calcium bentonites maintained hydration levels in long-term. Nonwoven geotextile facing down favored capillary effects. Thermal cycles significantly influenced GCLs hydration from subsoils. Capillary connections developed during hydration under isothermal conditions due to suction gradient reductions. Post-hydration tests under isothermal conditions showed more alterations in GCLs swelling and cation exchange properties than thermal cycles test. An increase in the saturated hydraulic conductivity of GCLs was observed in both lateritic soils, mainly for isothermal condition, although continued attending hydraulic conductivity requirements for barrier applications. • GCLs with activated-calcium bentonites maintained hydration levels in long-term. • GCL with granular bentonites were less efficient to hydrate from lateritic subsoils. • Nonwoven geotextile facing down favored capillary effects. • Thermal cycles significantly influenced GCLs hydration from subsoils. • Isothermal conditions showed more alterations in GCLs properties than thermal conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] In recent years there has been an increasing research interest in the development of airborne-based Ground Penetrating Radar (GPR) systems for safe and fast detection of buried threats such as landmines and Improvised Explosive Devices (IEDs). Compared to other sensors such as metal detectors or magnetometers, GPR is able to detect either metallic and non-metallic targets. Besides, the use of Ultra Wide Band (UWB) radiofrequency hardware allows retrieving high resolution images of the subsoil, thus improving the detection capabilities. Airborne-based GPR systems are affected by uncertainties that need to be characterized and corrected. This contribution focuses on the following three issues: (i) influence of the height information in the GPR-Synthetic Aperture Radar (GPR-SAR) images, determining which sensors provide better quality images; (ii) distortion of the imaged targets in along-track axis due to small tilting of the UWB antennas on board the UAV, proposing a co-registration technique to correct it; and (iii) revision of SVD filtering techniques, assessing a criterion to classify the different eigenimages. The analysis of these issues, as well as the validation of the proposed correction methods, are conducted using measurements taken during validation campaigns of the implemented airborne-based GPR system. For this purpose, two validation scenarios with different soil characteristics have been selected. Metallic and non-metallic targets with different shapes and sizes have been buried in them. In the case of the first scenario (wet loamy soil), detection capabilities improved from 50% (5 out of 10 targets were detected) to 80%. For the second validation scenario (loamy soil, but less humid than the first scenario), not only a 100% detection is achieved, but also the targets are clearly imaged in the GPR-SAR images obtained with the improvements presented in this contribution. [ABSTRACT FROM AUTHOR]

This paper tackles the volumetric representation of geophysical and geotechnical data, gathered during exploration surveys of the subsoil; in particular, we focus on the modeling and analysis of underwater deposits. The creation of a 3D model as support to geological interpretation has to take into account the heterogeneity of the input data, coming from offshore acquisition campaigns. Some data are massive, but cover the domain unevenly, e.g., along dense differently spaced lines, while others are very sparse, e.g., borehole locations with soil sampling and CPTU (Piezocone Penetration Test) locations. A automatic process is presented to generate the subsurfaces and volume defining a sub-seabed deposit, starting from the identification of relevant morphological features in seismic data. In particular, simplification and refinement based on geostatistics have been applied to generate regular 2D meshes from strongly anisotropic data, in order to improve the quality of the final 3D tetrahedral mesh. Furthermore, we also use geostatistics to predict geotechnical parameters from local surveys and estimate their distribution on the whole domain: in this way the 3D model will include relevant geological features of the deposit and allow extrapolating different geotechnical information with associated uncertainty. The volume characterization and its 3D inspection will support geological analysis and planning of future engineering activities. The developed methodology has been tested on two real case studies. • We implemented a complete pipeline for the 3D modeling of stratified deposits • Our research action follows the surface-based approach • We combine computer graphics methodologies with geophysics and geostatistics [ABSTRACT FROM AUTHOR]

Phosphorus (P) accumulation in soils of the greenhouse vegetable production (GVP) system is common due to intensive fertilization. However, the mechanism of P cycling in soils containing high P concentrations is not clear. In order to clarify the P cycling in GVP, 10 topsoils (0 30 cm) and 10 subsoils (30 60 cm) were sampled under two types of greenhouses (solar greenhouse and plastic greenhouse) in Shouguang, a typical GVP region of China. The pools of soil inorganic P following Hedley sequential extraction, and the oxygen isotopic composition of NaHCO 3 extracted phosphate (δ 18O NaHCO 3 _Pi) and HCl extracted phosphate (δ 18O HCl_Pi) were measured. Results showed that P in GVP, particularly in the solar greenhouse soils, accumulated significantly both in topsoil and subsoil. The main inorganic P pool in GVP soils was the HCl extracted, accounting for 50.26 % 72.76 % in topsoil and 44.42 % 57.89 % in subsoil, respectively. Values of δ 18O NaHCO 3 _Pi in most topsoil samples were within the isotopic equilibrium range (13.63 ‰ 17.14 ‰). Values of soil δ 18O HCl_Pi in GVP, significantly higher than that in open field (11.41 ‰ in topsoil and 10.27 ‰ in subsoil), indicated more intensive P biological cycling and more secondary minerals formation altered the original characteristics of δ 18O HCl_Pi in GVP soil. The significant positive correlation of δ 18O NaHCO 3 _Pi values between topsoil and subsoil implied that the labile P i in subsoil was mainly influenced by its corresponding topsoil. Partially labile P, without biological cycling after fertilization of the topsoil, quickly migrated to the subsoil causing the P accumulation in the subsoil. The higher values of δ 18O NaHCO 3 _Pi and δ 18O HCl_Pi in solar greenhouse than plastic greenhouse suggested higher degree of P biological cycling, which were determined by the nutrient status. Overall, the phosphate oxygen isotope technology provides a deeper understanding of soil P cycling in GVP. • Phosphate oxygen isotope technology (δ 18O P) is a powerful tool for tracing P cycling. • The main inorganic P (P i) pool in GVP soils was the HCl-extracted P i. • Significant positive correlation of δ 18O NaHCO 3 -Pi was found between topsoil and subsoil. • Higher δ 18O P indicated more intensive biological cycling of P in solar greenhouse soil. • Secondary minerals in GVP soil alters the original characteristics of δ 18O HCl-Pi. [ABSTRACT FROM AUTHOR]

Organic matter (OM) injection into subsoil is expected to improve subsoil properties and thus increase crop nutrient and water uptake from the subsoil. Nevertheless, detailed knowledge of the fate and persistence of injected OM in subsoil does not yet exist. For this study, we sampled a field experiment, where two types of compost of different composition (Bio-waste compost and Green-waste compost, differing in carbon:nitrogen ratio) had been injected into the subsoil at three application amounts each (3, 5, and 7 kg dry mass m−1), and assessed the distribution of soil organic carbon (SOC) into different density fractions, the temperature sensitivity of soil respiration (Q10), and microbial necromass in subsoil. The results demonstrate that both Bio-waste and Green-waste compost injections enhanced the SOC stock, respiration rates, and temperature sensitivity in both top- and subsoil. In the subsoil, respiration rates were increased by 78 %, simultaneously compost addition enhanced microbial growth (increase in fungal residues by 123 %) but also increased the amount of carbon (C) in the mineral fraction. Significant differences in the δ13C values of density fractions and Q10 values were only detected between compost types rather than the amount of injected compost. Especially the Bio-waste compost with a narrower C:N ratio contributed to slightly greater soil labile C content, and ultimately elevated respiration rates in the subsoil. Hence, the fate of subsoil incorporated C is controlled by its composition rather than by the injected amount. Moreover, a higher contribution of fungal necromass C to the increase in Q10 values after compost injection was observed in the present study than for bacterial necromass C, suggesting that fungi are largely responsible for the final, enhanced storage of the C injected. [Display omitted] • Compost injected into subsoil enhanced SOC stock, respiration rates, and Q10. • Composition rather than quantity dictates the fate of subsoil injected C. • Fungi are largely responsible for the final, elevated storage of injected C. [ABSTRACT FROM AUTHOR]

The Cone Penetrometer Test (CPT) is one of the preferred tools to carry out sub-soil investigations. Numerical simulations of CPTs are employed as complements to laboratory experiments and improve understanding of soil behavior. Various numerical methods and soil models have been developed to simulate CPTs in controlled environments such as calibration chambers. In this study, a comparative analysis of three advanced soil models—DeltaSand, hypoplasticity with intergranular strain, and Hardening Soil with small strain stiffness— is performed in CPT simulation. The Material Point Method is employed to allow for the large deformations occurring during CPT. In this study, after calibration of the material models using experimental lab tests, the results of CPT simulations are compared with experimental data in terms of cone resistance and soil deformations near the cone penetrometer tip. The effect of material parameters in soil model which represent the behaviour of soils at small strains is evaluated on the CPT results. The performance of all soil models in predicting the stress evolution under the cone and at different distances from it is also evaluated. The findings clarify the strengths and weaknesses of these soil models and their accuracy, which allow a better understanding of their capabilities and limitations. [ABSTRACT FROM AUTHOR]

Continuous rotary tillage has resulted in several issues, including a thin tillage layer with low soil organic carbon (SOC) and soil compaction, impeding crop root development and resulting in low crop yields, especially in clay soils. Although deep tillage can increase crop yields by loosening the soil structure and expanding the tillage layer it is rarely applied in soils with high clay contents (such as lime concretion black soil) because of its high energy consumption and low economic benefit. This study aimed at investigating the modified tillage practice with lower energy consumption (combining rotary and deep tillage to return crop straw into different depths among different years) in the higher crop yield on a clay soil. We conducted a 5-year (2017–2021) field experiment in a lime concretion black soil with high clay content. The experiment included four treatments: conventional tillage (CT) to return crop straw into the 15-cm layer without and with fertilizer addition, modified tillage (MT) to return crop straw into different depths (i.e., 35 cm in 2017, 20 cm in 2018, 10 cm in 2019, and 20 cm in 2020) with fertilizer addition, and MT combined with fertilizer and activator addition. We investigated the crop yields, soil physicochemical properties, and microbial communities at the topsoil (0–15 cm) and subsoil (15–30 cm) layers. Compared with CT, MT increased maize (Zea mays Linn.) and wheat (Triticum aestivum L.) yields by 9.8 % and 11.4 %, respectively, by enhancing the SOC content and improving the soil physical properties of the subsoil (i.e., aggregate stability, macroaggregate proportion, soil porosity, and the proportion of large and small pores). We suggest a scientific tillage practice for future attempts to increase SOC sequestration and promote crop productivity in agricultural soils, especially those with a high clay content. • Combining rotary and deep tillage increased crop yield in lime concretion black soil. • Combining rotary and deep tillage increased soil organic carbon content of subsoil. • Combining rotary and deep tillage improved soil physical structure of subsoil. [ABSTRACT FROM AUTHOR]

• Changes in carbon management index (CMI) across key Chinese croplands assessed. • CMI the most robust in low-fertility topsoil and high-fertility subsoil. • C accumulation and lability regulated by soil depth and inherent site fertility. • CMI regulated by soil nutrients and mean annual temperature in all sites. Evidence for the variability of the carbon (C) management index (CMI) across surface and subsurface soil layers due to long-term fertilization in diverse agroecological settings is inadequate. Thus, our study aimed to explore the variations in soil organic C (SOC), CMI, and its response ratio (RR-CMI) along soil profiles (0–60 cm) across four croplands in China. These croplands represented two high-fertility sites in Gongzhuling (GZL) and Chongqing (CQ) and two low-fertility sites in Zhengzhou (ZZ) and Qiyang (QY). We evaluated various treatments: control (CK; no fertilizer), inorganic fertilizer (NPK), NPK combined with standard manure (MNPK), and 1.5 times the standard rate of manure and NPK (1.5MNPK). The results indicated a significant increase in SOC content across all depths, ranking as 1.5MNPK > MNPK > NPK > CK, with ranking for the pattern observed across sites as GZL > CQ ≈ QY > ZZ. This led to the most substantial increases, reaching 107, 86, 105, and 62 % more than CK across the soil profile (0–60 cm) under 1.5MNPK across all sites. Moreover, the same treatment showed a significantly higher CMI at 0–60 cm compared to CK, with increases of 37, 19, 65, and 25 % for ZZ, QY, GZL, and QY, respectively. Notably, for the low-fertility soils (ZZ and QY), a higher CMI was observed in the 0–20-cm soil layer), whereas the opposite was true for the high-fertility soil (GZL). Consequently, low-fertility soils exhibited a higher RR-CMI in the 0–20-cm soil layer, whereas the high fertility site (GZL) showed a higher RR-CMI in the 40–60-cm soil layer, suggesting differential accumulation and loss of SOC regulated by soil depth and inherent site fertility. Partial least squares regression analysis further indicated that soil and climatic factors predominantly influenced CMI under long-term fertilization in typical Chinese soils. In conclusion, the long-term application of manure combined with inorganic fertilizer promotes SOC sequestration and enhances CMI, presenting a viable management strategy for enhancing soil quality in the studied regions. [ABSTRACT FROM AUTHOR]

Understanding changes in root traits of high-yielding genotypes that consistently perform during different drought periods is crucial for improving wheat production and yield stability. A 2-year field trial and a pot experiment were conducted to determine the response of root growth and grain yield to early and terminal droughts in old and modern cultivars (FC3: 1960s and CH1: 2010s) under rainfed and irrigated conditions in the field. Rainfed wheat faced terminal drought in 2015–2016 and early drought in 2016–2017. Plants in the pot experiment were exposed to terminal drought, early drought, and well-watered. Both field and pot experiments showed higher grain yield in modern cultivar CH1 compared to FC3. Early and terminal droughts reduced grain yield in both cultivars, with a greater reduction in FC3. CH1 exhibited higher yield stability under drought conditions and experienced less reduction in early drought. Compared to FC3, CH1 produced more root biomass in the early growth stage. At anthesis, CH1 had significantly lower root biomass and root length density in the topsoil layer (0 0.2 m) and higher in the subsoil layer (0.2 1.0 m) than FC3, respectively. At maturity, the retention rate of subsoil root biomass in CH1 was higher, especially under early drought (80.2 % in field and 93.9 % in pot experiments). Both cultivars consumed similar seasonal water use, but CH1 reduced pre-anthesis water use and consumed more water after anthesis. This study indicates that modern cultivar had vigorous root growth at early stage. A higher proportion of root biomass preserved in deep soil after anthesis enhanced post-anthesis water use and photosynthetic rate, improved post-anthesis dry matter accumulation, and thus resulted in higher thousand kernel weight. These factors ensure higher yield and yield stability under both early and terminal drought stress. • Modern cultivar exhibitd consistent grain yield even in the face of early and terminal drought stress. • Early vigor roots of modern cultivar enhances water retention facilitating rapid recovery following early drought. • More surviving deep root increase post-anthesis dry matter accumulation and thousand kernel weight. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ca- OC and clay + silt-OC played a vital role in the stability of MAOC. • Ca- OC and clay + silt-OC contributed to the sequestration of MAOC. • MAOC persistence was positively correlated with the MAOC sequestration. Mineral associated organic carbon (MAOC) accounts for a substantial portion of soil organic carbon (SOC) due to its tendency for physicochemical bonding with mineral surfaces. However, the mechanisms controlling MAOC stability and sequestration upon erosion and deposition remain unclear. We collected samples from topsoil (0–20 cm) and subsoil (60–80 cm) in an eroding loess landscape in Northwest China. SOC was fractionated into particulate organic carbon (POC) and MAOC, and OC retained by reactive mineral phases (calcium, iron, and aluminum) were studied. Adsorption-desorption experiments were performed to quantify the OC capture capacity, and thermogravimetric techniques were used to determine the thermal stability of MAOC. Although POC dominated in the soil mass distribution (>60 %) in both sites, the MAOC in the topsoil and subsoil in the depositional sites was characterized by 1.38–3.88 times higher OC contents than the eroding sites. Furthermore, depositional sites featured 1.19–1.45, 1.43–1.72, and 1.28–1.96 times higher maximum adsorption capacity, specific mineral surface area, and silt + clay contents, respectively, than these of the eroding sites, indicating high OC sequestration capacity in the soils of depositional sites. Erosion directly transports soil materials (e.g., OC and fine particles) to the depositional sites, when coupled with the high OC capture capacity, this leads to an increase in the OC content from 0.50 to 1.37 at the eroding sites to 2.19–3.28 mg g−1 at the depositional site. The content and chemical structure of organic-metal complexes had minor differences, however, MAOC in the depositional sites was observed to have excellent thermal stability. Calcium-, and silt + clay-associated OC (Ca-OC and CS-OC) were positively correlated with the MAOC stability and content. Overall, our findings highlight the important role of Ca-OC and CS-OC in determining the stability and sequestration of MAOC in eroding loess landscapes. [ABSTRACT FROM AUTHOR]

Emerging microbial trait-based approaches for soil organic carbon (SOC) storage advocate enhancing specific soil microbial functional traits, such as increased carbon use efficiency (CUE) and enzymatic efficiency (EE) and decreased metabolic quotient (qCO 2). These traits facilitate the efficient conversion of crop residues into microbial biomass C (MBC), that is subsequently stabilized as SOC in the soil mineral fraction. However, our current understanding of SOC dynamics in croplands is mainly confined to topsoil or tillage zone, and the field-based evidence for subsoil microbial functional trait dynamics is sparse. To address this knowledge gap, we studied the effect of contrasting long-term agricultural management practices on microbial functional traits favoring SOC accumulation in topsoil and subsoil by conducting a laboratory experiment using 13C labeled glucose addition. Our results show a 19 % increase in C growth (C allocated for microbial biomass growth), 11 % increase in CUE and 14 % increase in EE under no-till (NT) compared to conventional till (CT) in topsoil (0–10 cm) and no difference in these microbial parameters in subsoil (30–40 cm) between NT and CT. Growing a deep-rooted winter wheat (WW) cover crop increased CUE by 28 % in the topsoil and 11 % in the subsoil compared to no-cover treatment. We found separate drivers controlling SOC accumulation in topsoil and subsoil. These drivers are increased particulate organic matter C (POM–C) and C growth , under NT in topsoil and increased C growth over respiration and mineral associated organic matter C (MAOM–C), under WW in subsoil. Overall, our results provide experimental evidence that different microbial functional traits, molded by different long-term conservation practices, dictate SOC storage in agricultural topsoil and subsoil. • Long-term no-tillage improved topsoil microbial carbon use and enzymatic efficiencies. • Deep-rooted cover crop improved subsoil microbial carbon use and enzymatic efficiencies. • Higher particulate organic C and microbial growth increased topsoil C under no-tillage. • Higher particulate organic C and microbial growth with reduced respiration increased subsoil C under winter wheat cover crop. [ABSTRACT FROM AUTHOR]

After over 20 years of practicing shallow rotary tillage combined with straw direct return in the middle and lower Yangtze regions of China, the yield potential has gradually disappeared, and new alternative tillage practices are required to continuously increase rice yield. This paper investigates the yield effect and mechanism of deep tillage combined with straw return through two consecutive years of a field experiment. Three tillage depths (shallow tillage 6–7 cm, ST; medium tillage 12–14 cm, MT; and deep tillage 25–28 cm, DT) plus three straw management methods (no straw return, NR; straw direct return, SR; and straw biochar return based on the same amount of carbon input as SR, BR) were set up as experiment treatments. The aboveground and belowground growth traits of rice and soil nitrogen (N) status were determined. Compared with ST and MT, the DT enlarged rice root distribution and increased soil N content in the middle and lower soil layers (7–28 cm) and decreased the root–shoot ratio at the flowering stage, which was conducive to absorbing more soil nutrients from the subsoil and allocating more photosynthetic products to the aboveground parts and grain. The MT and DT increased spike number and rice yield compared with ST. Compared with NR, both SR and BR increased soil total and available N contents, and the remaining soil available N content at the harvest stage of BR was lower than that of SR. Straw return (SR and BR) improved rice yield by increasing spike number and kernels per spike, and the effect of BR on increasing rice yield was greater than that of SR. The DT combined with BR increased root distribution and N content in the subsoil, promoted the utilization of subsoil's nutrients, and increased rice yield. It is therefore a promising tillage practice for achieving high rice yields. • DT increased root distribution and N content in the subsoil. • DT had the lowest root-shoot ratio, allocating more biomass to aboveground growth. • DT increased spike number and straw return increased spike number and kernels per spike. • DT combined with BR is a promising approach for increasing rice yield. [ABSTRACT FROM AUTHOR]

Freeze-thaw (FT) processes in cold regions significantly influence the mineralization and sequestration of soil organic carbon (SOC), particularly in its active pools, such as dissolved organic carbon (DOC) and microbial biomass carbon (MBC). However, manipulation experiments often amplify the effects of natural FT processes and overlook soils below 20 cm depth. To investigate carbon responses to seasonal FT events across soil depths (0–80 cm) and identify controlling factors, field sampling was conducted before freezing and after thawing in alpine grassland soils on the Qinghai-Tibet Plateau. Results are as follows: 1) After soil thawing, the entire soil profile showed insignificant changes in SOC (−4.46%) and MBC (3.21%), but DOC (45.27%) and DOC/SOC (160.08%) increased significantly, and strong associations were observed in DOC changes between adjacent soil layers. 2) FT indicators (number and temperature amplitude of daily FT cycles, frozen temperature, and frozen days) influenced SOC changes differently in the topsoil (0–10 cm) and subsoil (20–30 cm). Contrary to the impact of frozen temperature, other FT indicators largely facilitated the production of DOC 0–10 and DOC 20–30. The effects of FT indicators on MBC were nonlinear. 3) Structural equation models indicated that average soil water governed FT-induced changes in both DOC 0–10 and DOC 20–30. The varying effects of porosity and pH from topsoil to subsoil, along with the weakening relationship between changes in DOC and MBC, favored a stronger increase in DOC 20–30. Increases in soil water and DOC after thawing stimulated the increment of MBC 0–10 , while porosity (positively) and sand content (negatively) regulated the MBC 20–30 change. It indicates that, influenced by soil structure and biogeochemical environment, DOC and MBC in grassland soils are more sensitive to natural FT processes than SOC. Nevertheless, changes in FT patterns due to long-term climate change may cumulatively affect SOC. [ABSTRACT FROM AUTHOR]

This research focuses on the Cathedral Church of Saint Mary in Murcia, Spain, which is located in a moderate-to-high seismic risk zone in the Spanish context. The study uses geophysical techniques and geotechnical investigation to characterise seismic ground models at the building's scale, aiming to understand the real amplification of the ground under seismic effect in historic buildings. Three soil layers (silt, sand with gravel, and gravel) were identified through core borings. Multichannel Analysis of Surface Waves (MASW) profiles and Mini-array profiles revealed Vs values of 305 ± 32 m/s, 296 ± 62 m/s, and 440 ± 38.5 m/s, respectively, for these materials. Seismic Refraction Tomography (SRT) showed Vp values of 586 ± 73 m/s, 700 m/s, and 1466 ± 489 m/s for the corresponding layers. The horizontal-to-vertical spectral ratio (HVSR) approach identified a ground predominant period ranging from 0.37 to 0.38 s. Another significant peak at 2.3 s is observed, probably associated to the Triassic basement. Three seismic events with magnitudes Mw between 4.9 and 5.1 were used as inputs to determine the amplification factor (AF). The results indicate a PGA amplification factor between 1.7 and 2.1. These results contribute to the conservation and mitigation of seismic risk of this cultural heritage generating input data that enables precise computation of the soil-structure interaction. • Seismic response of the soil underneath a historic building has been characterised. • Seismic characteristics of the ground are calculated using geophysical techniques and boreholes. • 3D velocity model of the subsoil of the Cathedral of Murcia is determined. • The PGA amplification factor is determined by using three seismic events as inputs. [ABSTRACT FROM AUTHOR]

• Nano-Fe 3 O 4 combined with wheat straw mitigated nitrate leaching. • Nano-Fe 3 O 4 enriched denitrifying and DNRA populations. • Nano-Fe 3 O 4 drove bacterial community towards bioactive nitrogen recycling. Nanotechnology and biotechnology offer promising avenues for bolstering food security through the facilitation of soil nitrogen (N) sequestration and the reduction of nitrate leaching. Nonetheless, a comprehensive and mechanistic evaluation of their effectiveness and safety remains unclear. In this study, a soil remediation strategy employing nano-Fe 3 O 4 and straw in N-contaminated soil was developed to elucidate N retention mechanisms via diverse metagenomics techniques. The findings revealed that subsoil amended with straw, particularly in conjunction with nano-Fe 3 O 4 , significantly increased subsoil N content (53.2%) and decreased nitrate concentration (74.6%) in leachate. Furthermore, the enrichment of functional genes associated with N-cycling, sulfate, nitrate, and iron uptake, along with chemotaxis, and responses to environmental stimuli or microbial collaboration, effectively mitigates nitrate leaching while enhancing soil N sequestration. This study introduces a pioneering approach utilizing nanomaterials in soil remediation, thereby offering the potential for the cultivation of safe vegetables in high N input greenhouse agriculture. [ABSTRACT FROM AUTHOR]

This study aims to determine the palaeoenvironmental characteristics and activity patterns of Obrovac-type archaeological sites in Western Serbia, dated to the Late Neolithic/Early Eneolithic period, ∼5th millennium BC. These mound-like sites, enclosed by a wide ditch, that are not known in other parts of the central Balkan area, have long intrigued archaeologists investigating their origin and function over the last few decades. In this study, for the first time, organic-geochemical analysis of paleosol samples from the Obrovac-type sites was applied with the aim of palaeoenvironmental reconstruction. Additionally, organic carbon content and anion analysis of 58 subsoil samples from these settlements were performed to determine the use of space and activity zones. The analysis of biomarkers from selected sites suggests significant plant biodiversity in the Mačva region during the Late Neolithic/Early Eneolithic. Distribution of n -alkanes with the maximum at n -C 25 and predominance of C 30 hop-22(29)-ene among hopanoids in samples from Obrovac type-sites indisputably indicates that macrophytes are a dominant source of organic matter, implying a marshy and floodplain depositional environment. On the other side, a strong signal of long-chain n -alkanes indicates the input of terrestrial plants into the precursor biomass, confirming that this environment was habitable for the first settlers in this region. Anion-based analysis delineates certain activity zones, demonstrating that Obrovac type-sites manifest rather complex spatial behavior despite their relatively small size and available space. [ABSTRACT FROM AUTHOR]

Hydration tests were performed on geosynthetic clay liners (GCL) to examine the influence of subsoil water content (w subsoil) and mass per unit area (MPUA) on the cation exchange occurred during hydration. Increase in the w subsoil increased the final water content of GCL (w final). At MPUA of 4.0 kg/m2, w final increased from 70 to 109%. Such increase was less pronounced when MPUA was considered. Also, an inverse relation between MPUA and w final existed where w final increased as the MPUA decreased. The greatest w final was determined when w subsoil was ∼17% and MPUA of GCL was ∼3.0 kg/m2 (112%). The exchange reaction was the most favorable when w subsoil was ∼8% and MPUA of GCL was ∼3.0 kg/m2 (mole fractions of monovalent cations, X M , decreased from 0.81 to 0.65) and the least favorable when w subsoil was ∼17% and MPUA of GCL was ∼3.0 kg/m2 (X M decreased from 0.81 to 0.80). Combined influence of MPUA and w subsoil showed that although cation exchange depends on both factors, w subsoil had significant role in this reaction more than MPUA. The findings of cation exchange analyses were supported with swell index tests. The hydrated GCLs had lower swell indices than the virgin GCL (17.5–19.0 mL/2g vs. 21.5 mL/2g), indicating cation exchange. • Subsoil water content and mass per unit (MPUA) are of GCL affect the hydration behavior of GCLs. • Cation exchange is more favorable on drier subsoil conditions. • Subsoil pore fluid chemistry has an important role on cation exchange. • Subsoil water content has more influence on hydration and cation exchange than MPUA. [ABSTRACT FROM AUTHOR]

Soil arching and tensioned membrane effects are two main load transfer mechanisms for geosynthetic-reinforced pile-supported (GRPS) embankments over soft soils or voids. Evidences show that the tensioned membrane effect interacts with the soil arching effect. To investigate the soil arching evolution under different geosynthetic reinforcement stiffness and embankment height, a series of discrete element method (DEM) simulations of GRPS embankments were carried out based on physical model tests. The results indicate that the deformation pattern in the GRPS embankments changed from a concentric ellipse arch pattern to an equal settlement pattern with the increase of the embankment height. High stiffness geosynthetic hindered the development of soil arching and required more subsoil settlement to enable the development of maximum soil arching. However, soil arching in the GRPS embankments with low stiffness reinforcement degraded after reaching maximum soil arching. Appropriate stiffness reinforcement ensured the development and stability of maximum soil arching. According to the stress states on the pile top, a concentric ellipse soil arch model is proposed in this paper to describe the soil arching behavior in the GRPS embankments over voids. The predicted heights of soil arches and load efficacies on the piles agreed well with the DEM simulations and the test results from the literature. • This paper investigated the effect of geosynthetic stiffness on soil arching evolution including development and degradation. • Soil arching deformation pattern depends on embankment height. • Concentric ellipse soil arch model can describe maximum soil arching development with geosynthetic reinforcement. [ABSTRACT FROM AUTHOR]

Geosynthetic-reinforced and pile-supported (GRPS) embankments are becoming more and more popular as this technique showed good performances in practice. Various design methods were introduced to analyze GRPS embankments. However, the applicability of these design methods was not always fully validated. This paper focuses on the review of projects containing field observations of GRPS embankments. The comparison results showed that the assumptions related to the subsoil support, geosynthetic, arching shape, and its evolution are not consistent in the analytical methods. Comparison results with twenty-five full-scale cases and six series of experiments emphasize that these available design methods produce significantly different results in predicting loads transfer mechanism. The analytical models predict arching for cohesionless fill better that for cohesive fill soils. Besides, the analytical methods which consider subsoil support such as the CUR226 and EBGEO methods give results that are in a better agreement with experimental data as compared to other methods which do not consider the subsoil support. The CUR226 (2016) analytical model seems to be able to give the best performance with measured data when compared to other design methods. Finally, the results pointed out that the limit equilibrium model is adequate and has good performance. • This paper focuses on the review of projects containing field observations of Geosynthetic-reinforced and pile-supported (GRPS) embankments. • Six well-known design methods are compared with measured data from twenty-five full-scale cases and six series of experiments. • Database of GRPS cases are provided, which is a benchmark for all models. • The comparison and evaluation of analytical models are presented for cohesive and cohesionless fill. • The limit equilibrium model is adequate and has good performance. [ABSTRACT FROM AUTHOR]

• A novel approach with high accuracy for analyzing maximum vertical stress. • Evaluation of vertical stress distribution using Smoothed-Particle Hydrodynamics-Finite Element Analysis (SPH-FEA) technique. • Soil calibration with different levels of moisture. • Relation between vertical soil stress and operating conditions such as tire traffic, wheel load, and moisture content of soil. Evaluation of vertical stress distribution in clay-loam soil using Smoothed-Particle Hydrodynamics-Finite Element Analysis (SPH-FEA) technique is presented in this research. The moist soil is modelled using the hydrodynamic elastic–plastic material and Murnaghan equation of state, while the tire is modelled using FEA in Visual Environment's Pam-Crash software. Soil-tire interaction is performed using the node symmetric node to segment with edge treatment method. A single-wheel tester in a soil bin environment was utilized to provide experimental data. The objectives of the experimental test were to (1) calculate maximum subsoil stresses in the subsoil at 1 to 15 passes of a wheel with loads of 1, 2, 4, and 5 kN on soil with moisture levels of 0, 10, 17, and 24%.; (2) calibrate soil with different levels of moisture (3) compare predicted soil stresses with experiments. The maximum stress at 20 cm depth increased with increasing soil moisture and also with high levels of tire load. In contrast, successive traffic showed a decreasing effect on soil stress. The coefficient of determination 0.97 shows the predictions agreed very well with experiments. The moist soil-tire interaction model will be further used to analyze the soil stress in different soil depths and different forward velocity. [ABSTRACT FROM AUTHOR]

Aspergillus flavus and its toxic metabolites-aflatoxins infect and contaminate maize kernels, posing a threat to grain safety and human health. Due to the complexity of microbial growth and metabolic processes, dynamic mechanisms among fungal growth, nutrient depletion of maize kernels and aflatoxin production is still unclear. In this study, visible/near infrared (Vis/NIR) hyperspectral imaging (HSI) combined with the scanning electron microscope (SEM) was used to elucidate the critical organismal interaction at kernel (macro-) and microscopic levels. As kernel damage is the main entrance for fungal invasion, maize kernels with gradually aggravated damages from intact to pierced to halved kernels with A. flavus were cultured for 0–120 h. The spectral fingerprints of the A. flavus -maize kernel complex over time were analyzed with principal components analysis (PCA) of hyperspectral images, where the pseudo-color score maps and the loading plots of the first three PCs were used to investigate the dynamic process of fungal infection and to capture the subtle changes in the complex with different hardness of the maize matrix. The dynamic growth process of A. flavus and the interactions of fungus-maize complexes were explained on a microscopic level using SEM. Specifically, fungus morphology, e.g., hyphae, conidia, and conidiophore (stipe) was accurately captured on the microscopic level, and the interaction process between A. flavus and nutrient loss from the maize kernel tissues (i.e., embryo, and endosperm) was described. Furthermore, the growth stage discrimination models based on PLSDA with the results of CCR C = 100 %, CCR V = 97 %, CCR IV = 93 %, and the prediction models of AFB 1 based on PLSR with satisfactory performance (R2 C = 0.96, R2 V = 0.95, R2 IV = 0.93 and RPD = 3.58) were both achieved. In conclusion, the results from both macro-level (Vis/NIR-HSI) and micro-level (SEM) assessments revealed the dynamic organismal interactions in A. flavus -maize kernel complex, and the detailed data could be used for modeling, and quantitative prediction of aflatoxin, which would establish a theoretical foundation for the early detection of fungal or toxin contaminated grains to ensure food security. • Macro-micro interaction mechanism of A. flavus -maize was revealed by Vis/NIR-HSI and SEM. • Spectral fingerprint difference of infected intact, pierced and halved samples were examined. • Dynamic change of fungal infection on samples was analyzed by PCA and average spectrum. • Morphological and microscopic level destruction of A. flavus on maize kernels was described. • Fungal growth periods and AFB 1 accumulation on maize kernels were analyzed quantitatively. [ABSTRACT FROM AUTHOR]

• Macroaggregation preferentially protected C 3 -C in the depositional position. • C 4 -C in three size fractions was significantly affected by soil depth. • Erosion and deposition decreased in O-alkyl C and increased in aromatic C within macroaggregate. • Erosion mainly shaped plant-derived C and chemical composition in macroaggregate associated OC. Macroaggregation is widely recognized as an important soil carbon (C) stabilization mechanism. However, in eroding landscapes, the relationships among soil aggregation, organic carbon (OC) sources, and chemical composition are poorly understood. In this study, we aimed to explore the effects of erosion and deposition on macroaggregation, OC sources, and chemical compositions in topsoil (0–20 cm) versus subsoil (80–100 cm) in a Mollisol agricultural landscape. The bulk soil was fractionated into macroaggregates (0.25–2 mm), microaggregates (0.053–0.25 mm), and clay and silt (<0.053 mm) using a wet sieving procedure. The plant sources of soil OC were quantified based on the stable isotope 13C (δ13C), and the chemical composition of macroaggregate associated OC (MaOC) was determined by solid-state nuclear magnetic resonance techniques. The results indicated that macroaggregates and MaOC comprised 45–72% of soil mass and 50–66% of soil OC, respectively. There was a reduction in macroaggregate-associated C 3 -derived C (C 3 -C) in the eroding position compared to that in the non-eroding position. However, similar amounts of C 4 -derived C (C 4 -C) were detected among three topographical areas, indicating the re-macroaggregation of eroded materials in the depositional position and preferential protection of C 3 -C. In the up-slope positions, topsoil MaOC was composed primarily of O-alkyl C (52%). Compared with the up-slope position, there was a considerable increase in the amount of aromatic C in the erosional macroaggregate fraction. However, at the eroding position, there was a marked increase in the proportion of substituted alkyl-C in the topsoil material, and deposition resulted in an increase in aromatic C in the subsoil. Overall, erosion and deposition change soil aggregation, and sources and composition of OC in different functional pools have important implications for the stabilization of organic matter along an eroding Mollisol hillslope. [ABSTRACT FROM AUTHOR]

• Denitrification rates were higher in channel sediments than in riparian bulk soils. • Nitrification and denitrification rates in riparian bulk soils decreased with soil depth. • Riparian topsoils harbored more nitrifying and denitrifying microorganisms than subsoils. • Nitrifying and denitrifying microbial communities were affected by climate and edaphic factors. Nitrogen (N) cycling in rivers is particularly active and dynamic due to excess nutrient inputs worldwide. However, the multidimensional spatial patterns of the activity and community structure of N-cycling microorganisms in rivers remain unclear, limiting our understanding of river ecological functions, especially N removal capacity. Here, we measured the nitrification and denitrification rates and identified nitrifying and denitrifying microorganisms using high-throughput sequencing of archaeal amoA , bacterial amoA, nirK , and nirS genes in channel sediments, riparian rhizosphere soils, and riparian bulk soils of 30 N-polluted rivers across China. Results showed that in the lateral dimension, nitrification rates in sediments did not differ significantly from those in rhizosphere and bulk soils, but denitrification rates were higher in sediments than in bulk soils. However, the archaeal amoA gene abundance in sediments was considerably lower than that in rhizosphere and bulk soils, and bacterial amoA gene abundance in sediments was greater than that in rhizosphere soils. In the vertical dimension, both nitrification and denitrification rates in riparian bulk soils decreased with soil depth, and topsoils harbored more nitrifying and denitrifying microbes than subsoils. Denitrification but not nitrification rates increased with latitude and altitude but decreased with increasing mean annual temperature and precipitation. Overall, these results provide new insights into the multidimensional spatial patterns of river N cycling at a large scale, which is crucial to evaluating the N removal function of global rivers. [Display omitted] [ABSTRACT FROM AUTHOR]

Plants can influence soil microbes through resource acquisition and interference competition, with consequences for ecosystem function such as nitrification. However, how plants alter soil conditions to influence nitrifiers and nitrification rates remains poorly understood, especially in the subsoil. Here, coupling the 15N isotopic pool dilution technique, high throughput sequencing and in situ soil O 2 monitoring, we investigated how a deep-rooted perennial grass, miscanthus, versus an adjacent shallow-rooted turfgrass reference shapes nitrifier assembly and function along 1 m soil profiles. In topsoil, the suppression of ammonia (NH 3) oxidizing archaea (AOA) and gross nitrification rates in miscanthus relative to the reference likely resulted from nitrifiers being outcompeted by plant roots and heterotrophic bacteria for ammonium (NH 4 +). The stronger tripartite competition under miscanthus may have been caused in part by the lower soil organic matter (SOM) content, which supported lower gross nitrogen (N) mineralization, the major soil process that produces NH 4 +. In contrast, below 10 cm soil depth, significantly greater gross nitrification rates were observed in miscanthus compared to the reference. This was likely driven by the significantly lower oxygen (O 2) in miscanthus than reference subsoil, which selected against aerobic heterotrophic bacteria but in favor of AOA. Overall, we found that plants can regulate AOA community structure and function through different mechanisms in topsoil and subsoil, with suppression of nitrification in topsoil and enhancement of nitrification in subsoil. • Plants employ distinct mechanisms to regulate nitrifiers in topsoil and subsoil. • Strong plant-heterotroph-nitrifier competition suppresses nitrification in topsoil. • Suboxic conditions select against heterotrophs but in favor of AOA in subsoil. [ABSTRACT FROM AUTHOR]

• High microbial activity in topsoil causes apparent PE shortly after substrate addition. • The input of C from fertilizers induces apparent PE at the 10–30 cm depth. • The release and decomposition of mineral-bound organic C shortly after substrate addition contributes to positive PE. • Negative PE in topsoil during later incubation stages is linked to reduced microbial biomass and substrate depletion. • In subsoil, positive PE and net C loss was caused by microbial N mining. Fertilization is crucial for increasing crop productivity and it alters soil microbial biomass and activities. These alterations exert implications for soil carbon (C) stocks, primarily through the priming effect (PE). Here, we investigated the mechanisms underlying PE and their impact on soil C stocks in paddy soils subjected to long-term (31 years) fertilization. Soils from four depths within the upper 40 cm layer, subjected to four fertilization types (no fertilizer, mineral fertilizer, mineral + straw, mineral + chicken manure), were incubated for 60 days with or without 13C-labeled glucose. Following substrate addition, an increase in isotopically unlabeled CO 2 efflux may stem from accelerated microbial turnover (apparent PE) or modified soil organic matter (SOM) mineralization (real PE). By analyzing microbial biomass (MBC), CO 2 and dissolved organic C (DOC) dynamics, we explored the partitioning of C from glucose into three pools. Following glucose addition (day 2), the SOM-derived MBC decreased by 4.7 % at 0–10 cm in unfertilized and by 6.3 % in mineral-fertilized soils. SOM-derived MBC also decreased in soils fertilized with straw- and chicken manure at 0–20 and 0–30 cm. Hence, the apparent PE closely correlated with fertilization types. At day 2, the SOM-derived DOC increased with the increase in extractable Fe2+ content, indicating high contribution of the released mineral-bound organic C in the DOC pool. Microbial decomposition of SOM-derived DOC and loss of unlabeled C through apparent PE increased the release of unlabeled CO 2 , resulting in a positive but low PE. After 60 days of incubation, the addition of glucose to the subsoils (30–40 cm) caused a net loss of C (positive PE) of 6.6–19 mg kg−1. In contrast, negative PEs were observed in the topsoil, indicating a decrease in microbial activity and C turnover. These findings suggested that fertilization regimes, whether involving long-term extra C input or not, can alter microbial biomass and turnover rates. Moreover, the C turnover mechanisms in paddy soils are complex, including apparent PE, release of mineral-bound organic C, and negative PE. Collectively, these processes can consequently change soil C stocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Controls on bacterial and fungal distribution in tropical volcanic topsoil and subsoil are assessed. • Bacteria thrive in soils enriched with less-degraded SOM and higher pH compared to fungi. • Fungi exhibit more resilience than bacteria to declines in SOM quality and pH. • Moisture shapes bacteria and fungi communities through controls on vegetation and edaphic properties. • Bacteria align closely with edaphic factors, whereas fungi are more strongly associated with vegetation. Soil bacteria and fungi are key drivers of biogeochemical cycling, yet their distribution and primary controlling factors are obscure in tropical volcanic regions. Moreover, bacteria and fungi exhibit varying sensitivities to environmental factors with poorly understood interactions among climate and edaphic factors. To address these gaps, we collected topsoil (0–15 cm) and subsoil (20–40 cm) (n = 24) across elevational transects in tropical volcanic regions of Tanzania (north-west and south-east slopes of Mt. Kilimanjaro: TW and TE) and Indonesia (Mt. Sibyak, Sumatra and Mt. Tengger, Java: IS and IJ). Bacterial and fungal abundances and community structures were assessed using real-time PCR and PCR amplification with 16S/ITS sequencing. We evaluated the impacts of geographic distance, climate, vegetation, soil organic matter (SOM) quality (e.g., mean residence time of SOM pools), and other edaphic properties (e.g., pH, active Al/Fe). Our results revealed that bacteria tend to have a higher abundance/diversity than fungi in carbon- and nitrogen-rich soils having less-degraded SOM. Fungi exhibited less variation than bacteria in abundance/diversity between topsoil and subsoil, likely due to their versatile substrate adaptability. Notably, bacterial and fungal community structures in IJ soils resembled those in TE soils more closely than IS soils, challenging the importance of geographical distance as a soil microbial determinant. Statistical models identified that moisture is a stronger factor than temperature in shaping the community structures of bacteria and fungi either directly or indirectly via regulating edaphic and vegetation properties. Overall, soil pH, active Al/Fe, and SOM quality control bacterial diversity and community structure, whereas soil pH primarily regulates fungal community structure, with vegetation type demonstrating a stronger influence than edaphic factors. In conclusion, climate, particularly moisture as characterized by excess precipitation (precipitation minus evapotranspiration), is the primary factor regulating bacteria and fungi distribution and emerges as a reliable predictor of soil microbial biodiversity. [ABSTRACT FROM AUTHOR]

Late Glacial and Holocene stabilized inland dunes of the European Sand Belt in eastern and central Poland are intensively bioturbated below recent soils and buried palaeosols. In the recent subsoil, a layer of massive, totally bioturbated sand (23–97 cm thick, mean 47 cm) with usually poorly visible bioturbation structures is present. It transits into the underlying transitional layer (51–180 cm thick, mean 112 cm thick), where primary parallel lamination is cross-cut by casts of roots and associated, mostly meniscate, cylindrical burrows. Down the section, the burrows become increasingly vertically oriented, whereas their orientation is variable in the upper part. Burrows in the soil and the totally bioturbated layer are produced for feeding, sheltering, breeding, or a combination of these purposes together by various groups of organisms. The deep, mostly vertical, meniscate burrows are produced by insects for overwintering: they burrow down, feed on roots, and return (in spring) along the same path. They can cluster close to the casts of tree roots. The development of such ichnofabrics requires at least hundreds of years. In some cases, only a part of the transitional layer is preserved between laminated sands because of subsequent erosion followed by rapid deposition. Ichnofabrics document the previous presence of a well-developed soil vegetated with trees. Vertical to oblique meniscate burrows developed in the transitional layer are characteristic of a new ichnosubfacies of the Entradichnus - Octopodichnus ichnofacies, which is named the European Sand Belt ichnosubfacies. This ichnosubfacies may occur in well-aerated, and well-drained, sandy substrates in similar climatic conditions elsewhere. • Post-Glacial stabilized inland dunes in Poland are deeply bioturbated below soils. • The bioturbated sand shows a totally bioturbated layer on a transitional layer below. • In the transitional layer, primary lamination is cross cut by vertical insect burrows. • The vertical insect burrows record migration for overwintering and feeding on roots. • The Entradichnus - Octopodichnus ichnofacies has the European Sand Belt ichnosubfacies. [ABSTRACT FROM AUTHOR]

• Suberin contributed more to bulk SOC stocks than cutin in topsoil and subsoil. • Of all monomers, suberin monomers were affected most by deep-ploughing. • Effects of deep-ploughing on suberin SOC stocks were not uniform for sandy and silty sites. • Changes in SOC stocks in topsoil and subsoil after deep-ploughing affected input of root-derived C. Roots can add significant amounts of carbon (C) to the subsoil, which improves soil physical properties and can mitigate climate change. About 5% of croplands in Germany have been deep-ploughed (30–120 cm) at least once. This can provide better root access to the subsoil and may increase yields, but little is known on the fate of root-derived C in the subsoil (at depth greater than 30 cm) after deep-ploughing. We hypothesized that five decades after deep-ploughing, root-derived C stocks were higher than conventionally ploughed treatments due to better root development. We analysed suberin and cutin monomers as tracers for root- and shoot-derived C at three former deep-ploughed sites in Northern Germany with different soil textures and deep-ploughing depths. Concentrations of suberin monomers in the soil positively correlated with root biomass; this was most pronounced at one sandy site, but had higher variability at the other two sites due to crops with different root systems in the crop rotation, lower root development, and more favourable conditions for C decomposition. Suberin contributed more to the bulk soil organic carbon (SOC) stocks than cutin throughout the soil profile at all sites. The contribution of suberin monomers to the bulk SOC stock at silty site Banteln and the sandy site Essemühle was 38% higher in the deep-ploughed plots than at the reference plot, respectively, these differences were most visible in the subsoil of Essemühle. We conclude that as C stocks and root development increase, suberin SOC stocks also increase, especially in sandy subsoils with low pH. [ABSTRACT FROM AUTHOR]

T he first stage of the structure life cycle, i.e. structural design, can be a source of eco-efficient outcomes. They can be achieved through optimisation of the amount of materials used, based of structural analyses. On the other hand the structure should be safe and reliably. The presented article conducts analyses aimed at assessing the accuracy, reliability, and safety of internal force values obtained with use of different subsoil models in reinforced concrete rectangular tank. The focus is on evaluating the performance of simplified subsoil models integrated into Finite Element Method (FEM) software: W1 (one-parameter Winkler model), W3 (three-parameter Winkler model) and DP (the tank modelled together with a solid subsoil simulated with the Drücker–Prager constitutive model). FEM was coupled with reliability analysis. The influence of the soil model on the values of internal forces in the tank walls (horizontal and vertical forces and bending moments) and in foundation slab (bending models) was assessed. The paper proves, by modelling the interaction of the structure with the soil, that the more simplified the FEM model, the values of internal forces differ from reality to higher extend. Therefore, the use of accurate models leads to structural optimization and ensures safety. In the analysed tank, in view of the watertightness demand, the reliability index of the structure was determined for the serviceability limit state of cracking. As the analyses have shown, the optimization of internal forces in the walls and foundation of the tank, through the use of an appropriate and reliable numerical model for analysis, results in a higher value of the reliability indices of individual sections for cracking and a lower probability of cracking. • We present influence of the subsoil model on the safety of reinforced concrete structure of prismatic liquid tank. • We compare numerical analyses of exemplary sewage tank. • We evaluate relationship between reliability index and subsoil model. • We connect FEM analysis with reliability analysis. • We provide the necessary information about consequences of simplification in subsoil modelling. [ABSTRACT FROM AUTHOR]

Root morphology and anatomical traits that occurred during the cultivar selection process are important for understanding improvements in grain yield and water use efficiency. However, little is known about the changes in root morphology and root anatomy caused by cultivar replacement and their effects on grain yield and water use efficiency. Field and pot experiments were conducted to investigate the changing trends in root morphological and anatomical traits of six dryland winter wheat cultivars widely cultivated in Shaanxi Province of China, from 1949 to 2014, and determine their relationships with grain yield and water use efficiency. The results illustrated that compared with old cultivars, the grain yield and water use efficiency of modern cultivars increased by 35.7% and 48.4% respectively, and were closely related to root system changes. With cultivar succession, root biomass, root surface area, root length and root length density all decreased in the topsoil under irrigated or rainfed conditions, whereas these traits increased in the subsoil. The subsoil root biomass, root surface area, root length and root length density of cultivars released after 2000 increased by 26.1%, 11.7%, 25.4% and 23.2% respectively compared with the older cultivars before 2000. Cultivar replacement also increased the root cortex thickness by 29.2%, but reduced the root xylem center vessel diameter by 13.2%, without obvious changes in root diameter. Our study demonstrated that cultivar replacement altered root morphology and root anatomy, thereby improving grain yield and water use efficiency. The future challenge for wheat breeding is to increase grain yield and water use efficiency under water-deficit conditions, which may be achieved by further promoting subsoil root development and optimizing root anatomy. • Assessed trends in root morphology and root anatomical traits during cultivar. • replacement is important for understanding improvements in yield performance. • Increased wheat grain yield during cultivar replacement was associated with changes in root morphology and root anatomical traits. • With cultivar succession, the distribution of roots in the topsoil layer decreased significantly, but increased in the subsoil layer. • Optimized root anatomy of modern cultivars facilitated water storage and showed yield superiority. [ABSTRACT FROM AUTHOR]

Ants are undisputed masters at transforming the local environments they inhabit, with subsequent vast effects on soil chemical and hydrological processes. Yet, it remains unclear how deep into the subsoil these effects range, as most ant-soil studies focus on the topsoil. Furthermore, studies quantifying these effects on podzolized, and nutrient-poor heathland soils remain scarce. We excavated 15 Formica exsecta ant mounds on a long-term, unmanaged heathland in Denmark. We sampled soil moisture, soil penetration resistance (SPR), pH, total phosphorous content, and the thickness of each soil horizon at three positions at each mound: directly below the mound, at the edge of the mound, and an adjacent undisturbed reference soil. Results revealed that ant activity reduced soil moisture, loosened the soil, and increased the flow of total phosphorus to the deeper layers. Importantly, the cemented spodic horizons (hardpans) with waterlogging properties were penetrated by ant digging, resulting in potentially higher water infiltration into the subsoil. The ant activity within the otherwise undisturbed sandy subsoil below the hard pan caused a slight alteration in the thickness of each soil horizon and chemistry. These patchy, small-scale disturbances (mounds covered 0.06 % of the site) increase heathland soil heterogeneity and affect subsoil properties in time. We conclude that ant mounds may play a previously overlooked role in heathland soil dynamics by penetrating the heathland hardpans and manipulating soil chemistry and soil moisture. We argue that a viable mound-forming ant community is valuable for the soil heterogeneity of dry heathland ecosystems. • Ants are important pedogenic factors in heathlands. • Conserving ant mounds is important for heathland soil heterogeneity. [ABSTRACT FROM AUTHOR]

Lumbricus terrestris is an epi-anecic earthworm, normally occupying a 1–2 m deep, vertical burrow. Some observations suggest that population persistence in much shallower burrows could be possible in a mild and humid climate. This was further investigated at an ex-industrial site in NW England, with a topsoil less than 0.15 m deep, above inert subsoil formed from semi-weathered Leblanc waste. L. terrestris were collected from an adjacent woodland soil and introduced into unoccupied areas. After four days, settlement and survival were studied by targeted sampling of half of the individuals, and depth of burrows were measured by resin casting. After 14 months, the second half of inoculated areas were studied and after another four years a further general survey occurred. After four days, 41 % of targeted worms were recovered, with 0.11 m mean burrow depth and burrows ending at the subsoil interface. After 14 months, all age classes of L. terrestris were present and burrow depth had not changed. After five years, adult, juvenile and hatchling L. terrestris were present, demonstrating establishment of a breeding population. In a parallel laboratory experiment, with site topsoil and subsoil in Evans' boxes, L. terrestris avoided subsoil and constructed U-shaped burrows. The results show that through flexible burrow construction, L. terrestris can survive above highly constraining subsoil conditions. This is likely to be only possible where severe droughts are uncommon, and topsoil does not freeze in winter. • Physico-chemical subsoil barriers can prevent normal deep burrowing of L. terrestris. • Adult L. terrestris can create burrows and settle in soils less than 0.15 m deep. • In a humid and mild climate, it is possible that a breeding population could persist for years in shallow soil. • Results have useful implications for L. terrestris inoculation in restricting subsoil conditions. [ABSTRACT FROM AUTHOR]

The intensification of modern arable farming has brought on a steady increase of the risk of soil compaction, while simultaneously pushing the impact deeper into the soil profile. In the subsoil, outside the reach of regular tillage operation, it can become exceedingly difficult to deal with compacted layers. Commonly, farmers turn towards mechanical remediation strategies, like subsoiling, to deal with this issue. However, the numerous drawbacks that come with these operations have prompted the search for more sustainable alternatives, like bio-subsoilers, which are deep-rooting plant species with the capacity to penetrate compacted subsoil layers. This study aimed at investigating both mechanical and biological remediation strategies in a side-by-side comparison. The effectiveness of subsoiling and the use of two deep rooting (cover) crops (i.e. alfalfa and fodder radish) as remediation measures to alleviate subsoil compaction was assessed in terms of soil quality indicators, like penetration resistance, bulk density, porosity, plant available water capacity, air capacity and air permeability at 35 and 45 cm depth, and the above- and belowground growth of the main crop. In addition, a combination of both subsoiling and use of deep rooting (cover) crops was included to evaluate the potential role of the latter in protecting the mechanically loosened subsoil from recompaction. This complex comparison was done in three distinct maize-based fodder crop rotations (rotation 1: maize monoculture; rotation 2: maize/winter cereal rotation with fodder radish as cover crop after winter cereal; rotation 3: maize/winter cereal/alfalfa rotation). The study field (sandy loam soil) was selected based on the presence of a highly compacted layer at the interface between topsoil and subsoil (30–50 cm). The experiment demonstrated that subsoiling is an effective remediation measure to disrupt heavily compacted layers in the upper-subsoil, at least in the short-term. The crop response was however highly variable and only positive when the opportunity of reaching the subsoil proved to be advantageous for the crop (i.e. dry season). Besides its high degree of variability between years, the effects also proved to be very short-lived under a standard arable fodder crop rotation. Including deep rooting (cover) crops, like fodder radish and alfalfa, and limiting the initial subsoil disruption helped to partially stabilize the disrupted subsoil and reduce recompaction. Fodder radish and alfalfa penetrated the compacted subsoil without previous disruption by subsoiling. However, this did not lead to a significant improvement of the measured soil physical parameters. • Subsoiling proved an effective remediation measure disrupt compacted subsoil layers. • The crop response was highly variable across the experimental years and treatments. • Recompaction remains a serious problem under a standard fodder crop rotation. • Deep-rooting (cover) crops could help to stabilize the disrupted subsoil. • Fodder radish and alfalfa managed to penetrate the compacted subsoil. [ABSTRACT FROM AUTHOR]

[Display omitted] • Does soil organic C differ in rice paddies and forests along a soil age gradient? • Total organic carbon stocks were similar between land uses. • Higher fraction of mineral associated organic carbon in paddy than in forest soils. • Translocation of iron oxide and organic carbon to subsoil stronger in younger soils. • Organic carbon increased with short-range ordered iron oxides in paddy subsoil. Rice paddy soils have high organic carbon (OC) storage potential, but predicting OC stocks in these soils is difficult due to the complex OC stabilization mechanisms under fluctuating redox conditions. Especially in temperate climates, these mechanisms remain understudied and comparisons to OC stocks under natural vegetation are scarce. Semi-natural forests could have similar or higher OC inputs than rice paddies, but in the latter mineralization under anoxic conditions and interactions between OC and redox-sensitive minerals (in particular Fe oxyhydroxides, hereafter referred to as Fe oxides) could promote OC stabilization. Moreover, management-induced soil redox cycling in rice paddies can interact with pre-existing pedogenetic differences of soils having different degrees of evolution. To disentangle these drivers of soil OC stocks, we focused on a soil age gradient in Northern Italy with a long (30 + years) history of rice cultivation and remnant semi-natural forests. Irrespective of soil age, soils under semi-natural forest and paddy land-use showed comparable OC stocks. While, in topsoil, stocks of crystalline Fe and short-ranged Fe and Al oxides did not differ between land-uses, under paddy management more OC was found in the mineral-associated fraction. This hints to a stronger redox-driven OC stabilization in the paddy topsoil compared to semi-natural forest soils that might compensate for the presumed lower OC inputs under rice cropping. Despite the higher clay contents over the whole profile and more crystalline pedogenetic Fe stocks in the topsoil in older soils, OC stocks were higher in the younger soils, in particular in the 50–70 cm layer, where short-range ordered pedogenetic oxides were also more abundant. These patterns might be explained by differences in hydrological flows responsible for the translocation of Fe and dissolved OC to the subsoil, preferentially in the younger, coarse-textured soils. Taken together, these results indicate the importance of the complex interplay between redox-cycling affected by paddy-management and soil-age related hydrological properties. [ABSTRACT FROM AUTHOR]