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The present study evaluates the amelioration of fat clay by blending it with cohesive non-swelling soil (CNS) and cohesionless silty sandy soil (Kassu). The fat clay sample with a liquid limit (LL) of 50 and a plasticity index (PI) of 26 was collected from Narowal, while CNS and Kassu samples were procured from Lahore's outskirts. Geotechnical tests on the virgin soil indicated its unsuitability for construction. Laboratory tests, including modified Proctor compaction, unconfined compression, California bearing ratio (CBR), and one-dimensional consolidation, were performed on samples blended with 0–35% CNS or Kassu in 5% intervals. The LL and PI of fat clay decreased significantly with the addition of 35% CNS (LL: 50–32%, PI: 24 to 13) and Kassu (LL: 50–29%, PI: 24–12). The CBR value increased from 4 to 7%, making the blended soil suitable for subgrade use. Unconfined compression tests showed a strength increase from 102 to 185 kPa with 35% CNS and up to 140 kPa with 25% Kassu. Compaction tests revealed improved maximum dry unit weight and reduced optimum moisture content. Swell potential decreased from 4 to 1.2 and 0.26% with CNS and Kassu additions. Regression models predict swell pressure and ultimate swell potential. The study concludes that blending fat clay with CNS and Kassu significantly improves its geotechnical properties, with CNS being more effective in controlling swell characteristics. [ABSTRACT FROM AUTHOR]

Aeolian sandy soil and loess soil of the Mu Us Sandy Land are used as the research material in this study to investigate the effect of soil compounding on the improvement of aeolian sandy soil and to provide a feasible approach for sand prevention and sand control. In particular, loess soils were compounded at 0%, 20%, 40%, 60%, 80%, and 100% by volume percentage of the compounded soils. The improvement benefits of compounded soils on their textural properties, water-holding capacity, and fertilizer-retention capacity at different blending ratios were evaluated. The results showed that following the compounding of aeolian sandy and loess soils, with the increase of the loess proportion, the texture type of the compounded soil transforms from sandy soil to loamy sandy soil to sandy loam to loamy soil to powdery loam. Moreover, granular gradation was observed, the bulk density gradually decreased, the capillary porosity gradually increased, and the performance of water- and fertilizer-holding properties gradually increased and strengthened. The spatial variability of compounded soil bulk density, capillary porosity, and the water-holding and fertilizer-retention properties was almost entirely controlled by the proportion of loess soil. A theoretical basis is provided in this study for aeolian sandy soil improvement in the Mu Us Sandy Land that can be extended to similar areas, providing a feasible sand management approach. [ABSTRACT FROM AUTHOR]

The aim of this work is to reveal correlation between the spectral characteristics of the open soil surface on the Pleiades image (April 25, 2020) and soils of a key site with a complex soil cover pattern in the south of the Volga Upland (Volga–Don irrigation system, Volgograd oblast). The study area is specified by the lithological heterogeneity: Paleogene and Neogene sands and loams are overlain by a mantle of Quaternary brown loams of variable thickness from 1–2 m to complete thinning out. The soil cover is represented by light chestnut solonetzic complexes complicated by a mosaic of lithological variants and erosion–accumulative combinations. Eight soil groups have been specified, and a map of their distribution has been developed for the key site of 343 ha with the use of digital methods of processing the spectral characteristics of the satellite image and ground-based soil information. Soil groups differ in general features of the soil surface due to differences in the contents of gravel and stones, texture of the surface horizon (from sand to silt loam), occurrence of brightened crusts, and surface effervescence depending on the thickness of the upper lithological layer. Soils with different horizonation of the profile—agrochestnut soils, agrozems, and agrosolonetzes—fall within the same groups of surface spectral characteristics; vice versa, soils of the same genetic type and, sometimes, subtype fall into different groups. This is explained by the incomplete correspondence of the properties of the soil surface affecting the spectral characteristics to the internal structure of the soil profile as a whole. [ABSTRACT FROM AUTHOR]

In this paper, a series of true triaxial tests with different intermediate principal stress ratios are conducted on both the lunar soil simulant and the sandy soils on earth using the discrete element method. An advanced discrete element servomechanism based on polyhedral specimen configuration is implemented such that true triaxial loading paths can be implemented under low confining pressure without introducing severe stress concentration. The high frictional angle and apparent cohesion of the lunar simulant are captured by employing a highly efficient contact model that fuses rolling resistance and van der Waals forces. The employed micro-scale parameters are calibrated based on the triaxial test results of the CSU-LRS-1 lunar soil simulant. The simulation results show that the lunar soil simulant exhibits lower shear strength with an increasing intermediate principal stress ratio. Generally, although the lunar soil simulant has a greater void ratio than that of sandy soils, the former exhibits significantly stronger shear-induced dilatancy and higher shear strength. The evolution of the load-bearing structure is quantified through a contact-normal-based fabric tensor. The interplay between internal structure evolution and external loadings can well explain the difference in mechanical behavior between lunar soil simulant and sandy soils on earth. [ABSTRACT FROM AUTHOR]

As the world struggles with climate change and energy crises, understanding the role of soil in the food–water–energy nexus becomes increasingly critical. Accurately estimating the soil thermal conductivity drying curve is essential for assessing the impacts of temperature on soil biota and crop growth, environmental changes due to forest fires and global warming, and for designing geo‐energy extraction techniques such as geothermal energy piles. Existing empirical models often fail to accurately estimate the soil thermal conductivity (TC), particularly in pendular soil moisture regimes where they do not capture sharp changes in TC. This study introduces a novel approach using a pore unit cell network model to more accurately describe the dynamics of TC in variably saturated soils. A quadratic parallel scheme within each soil pore unit cell links the TCs of solid, water, and air to the overall effective conductivity. By modeling air invasion in the pore network model and employing the proposed equation, we determined the unsaturated soil TC based on varying local conductivities. The model effectively captures the significant decrease in conductivity in the pendular saturation regime, associated with the shrinkage of the spanning‐wetting cluster. Quantitative analyses showed a substantial improvement in prediction accuracy compared to existing models, especially under varying moisture conditions. Our findings have significant implications for better characterizing soil thermal and hydraulic properties, which are crucial for resource management in a changing climate and advancing geo‐energy technologies. Core Ideas: Spanning‐wetting cluster shrinkage in the pendular regime significantly decreases soil thermal conductivity.Soil thermal conductivity is influenced by both the distribution and specific values of local pore saturation.Pore unit cell network modeling leads to more accurate estimates of the unsaturated thermal conductivity. [ABSTRACT FROM AUTHOR]

Currently, coastal sandy soils face issues such as insufficient foundation strength, which has become one of the crucial factors constraining urban development. Geotechnical engineering, as a traditional discipline, breaks down disciplinary barriers, promotes interdisciplinary integration, and realizes the green ecological and low-carbon development of geotechnical engineering, which is highly important. Based on the "dual carbon" concept advocating a green and environmentally friendly lifestyle, Bacillus spores were utilized to induce calcium carbonate precipitation technology (MICP) to solidify coastal sandy soils, leveraging the rough-surface and low-permeability characteristics of silty soil. The mechanical-strength variations in the samples were explored through experiments, such as calcium carbonate generation rate tests, non-consolidated undrained triaxial shear tests, and scanning electron microscopy (SEM) experiments, to investigate the MICP solidification mechanism. The results indicate that by incorporating silty soil into sandy soil for MICP solidification, the calcium carbonate generation rates of the samples were significantly increased. With the increase in the silty-soil content, the enhancement range was 0.58–3.62%, with the maximum calcium carbonate generation rate occurring at a 5% content level. As the silty-soil content gradually increased from 1% to 5%, the peak deviator stress increased by 4.2–43.2%, enhancing the sample shear strength. Furthermore, the relationship between the internal-friction angle, cohesion, and shear strength further validates the enhancement of the shear strength. Silty soil plays roles in adsorption and physical filling during the MICP solidification process, reducing the inter-particle pores in sandy soil, increasing the compactness, providing adsorption sites, and enhancing the calcium carbonate generation rate, thereby improving the shear strength. The research findings can provide guidance for reinforcing poor coastal sandy-soil foundations in various regions. [ABSTRACT FROM AUTHOR]

Sandy loamy soils are widely distributed in fluvial floodplains and experience flooding events frequently, resulting in a large amount of nitrous oxide (N2O) emissions. This case is more serious when the soil use is changed to paddies. It is of great significance to figure out the N2O consumption and its influencing factors in sandy loamy paddy soils to mitigate N2O emissions. In this study, three sandy loamy paddy soils (0–5 cm) originated from lake deposits were selected (S1, S2, and S3) as objectives. A certain concentration of exogenous N2O was added at the bottom of the flooded soil column to monitor the dynamics of N2O and nitrogen (N2) on the soil surface. Total N2O consumption, N2O uptake, and N2 production were quantified, and the abundance of nitrous oxide reductase genes (nosZI, and nosZII) and other soil properties (ammonium‐nitrogen, nitrate‐nitrogen, and dissolved organic carbon [DOC] content) were analyzed. The results showed that the sandy loamy paddy soil column with a depth of 0–5 cm could intercept more than 95% of the exogenous N2O under the flooded anaerobic condition, indicating that the three sandy loamy paddy soils all had extremely strong N2O consumption capacities. And the increment of N2 accounted for 68.73%–76.09% of the total N2O consumption, which had a stronger relationship with the increase of nosZI gene abundance than nosZII gene. In addition, the total N2O consumption and N2 increment of S1 and S3 soils were significantly higher than those of S2 soil. This difference was mainly related to soil organic matter content, total nitrogen content, DOC consumption, and the increase of nosZI gene abundance (p < 0.05). The strong N2O consumption potential of sandy loamy soils can provide feasible solutions for regulating N2O emissions in a wide range of similar environments in fluvial floodplains. Core Ideas: Over 95% of N2O in 5‐cm‐soil depth was consumed by flooded sandy loamy paddy soils.The microbial reduction of N2O to N2 is the main pathway of N2O consumption.N2O consumption and N2 increment dominated by nosZI‐containing microorganisms. [ABSTRACT FROM AUTHOR]

Evaluating the liquefaction capacity of saturated loose sandy and clayey soils is an important task to be completed in the course of implementing new construction projects in seismic areas. This article addresses the main characteristics and input parameters of three soil models, including HS small, UBC3D-PLM, and PM4Silt. The behavior of the "soil base–pile foundation–structure" system is examined by using these models to simulate the soil behavior during an earthquake. The results demonstrate the main differences between these models and draw attention to the importance of the choice of a soil model for seismic analysis, particularly when soil liquefaction is considered. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) is responsive to boron (B) fertilization when there is low soil availability, but the best source and rate to be used and whether this response is dependent on soil texture are still unknown. This study aimed to adjust boron fertilization for cotton as a function of the production environment and B source used. Two field experiments were conducted in the 2020/2021 season in Chapadão do Sul, MS (clayey soil—adequate B content) and Dracena, SP (sandy soil—low B content), Brazil. Treatments consisted of B sources (ulexite [low solubility], borax pentahydrate [BP] [intermediate solubility], and boric acid [BA] [high solubility]), and B rates (0, 1, 2, 4, and 6 kg ha−1) applied to the soil at 25 days after plant emergence. In sandy soil with low B content, application of 2 (high and medium solubility sources) and 4 kg B ha−1 (low solubility source) improved fiber yield between 10% (210 kg ha−1 fiber) and 28% (555 kg ha−1), respectively, as well as micronaire index, strength, elongation, uniformity, and short fibers. Application of B greater than 4 kg ha−1 via soluble sources reduced (between 9% (175 kg ha−1)—BP and 14% (257 kg ha−1)—BA) fiber yield only in sandy soil. When B content in the soil is adequate, B fertilization did not improve yield, but increased fiber strength (4%—1.1 g tex−1) and reduced the short fiber index (16%) by applying 1 kg B ha−1, regardless of the source used. The highest fiber yields were obtained with leaf B contents between 12 and 17 mg kg−1 (sandy soil) and 25 and 27 mg kg−1 (clayey soil). We recommend applying 2 kg B ha−1 (solubility sources) and 4 kg B ha−1 (low solubility source) in sandy soils with low B content to improve yield and fiber quality, and 1 kg B ha−1 in clayey soil with adequate B content to improve fiber quality and replace B amounts removed through harvesting. Core Ideas: Boron fertilization in sandy soils increased fiber yield by 210–555 kg ha−1.There are no effects of B fertilization in clayey soils on fiber yield, but there are improvements in fiber quality.Rates greater than 4 kg ha−1 of B via soluble sources reduce fiber yield in sandy soils.Cotton grown in clayey soil is more resistant to B toxicity. [ABSTRACT FROM AUTHOR]

Synchrotron X‐ray microtomography (XMT) was used to measure total air‐water interfacial areas (Aaw) as a function of water saturation (Sw) for several soils that comprise a range of physical and geochemical properties. Measurements were also conducted for glass beads and quartz sands for comparison. Apparent near‐linear Aaw‐Sw relationships are observed for the three sands and the three sandy soils. In contrast, the measured interfacial areas for two soils that contain greater proportions of silt and clay are strongly nonlinear functions of water saturation. The greater degree of nonlinearity observed for these two soils is due to their much greater particle‐size distributions (i.e., uniformity coefficients) and their concomitant greater range in pore sizes. Interfacial areas determined with the thermodynamic method were used to benchmark the XMT measurements. XMT‐measured interfacial areas compare well to the thermodynamic‐determined values for the sands and sandy soils. In contrast, the XMT‐measured interfacial areas for the two soils with larger particle‐size distributions are not fully congruent with the thermodynamic‐determined values. Both of these soils have large fractions of pore space comprising nominal pore diameters smaller than the resolution of the XMT imaging. These results suggest that air‐water interfacial area may not always be fully characterized by standard XMT for soils with large particle‐size distributions. Plain Language Summary: High‐resolution pore‐scale imaging is conducted for several sands and soils to examine the relationship between the magnitude of air‐water interfacial area and water saturation as well as to evaluate the effectiveness of the imaging method. Key Points: X‐ray microtomography (XMT) measurements of air‐water interfacial area are reported for soilsThe relationship between air‐water interfacial area and water saturation is nonlinearBenchmarking results indicate that XMT may not measure all interfacial area for soils with higher silt and clay contents [ABSTRACT FROM AUTHOR]

The mechanistic-empirical pavement design guide (M-EPDG) recommends the use of resilient modulus (MR) for characterization of subgrade soils. Subgrade soils may not always have enough strength and stiffness to support the pavement structure. Therefore, a certain type of soil improvement method using cement, lime, or other stabilization techniques is often needed to enhance the strength and stiffness properties of weak subgrade soils. The cement-stabilized soils show brittle behavior under compression loading, which can induce cracking in overlying pavement layers. In general, polymer-treated soils show a semiductile or ductile behavior. It is important to look for combined cement and polymer treatments to address brittle behavior issues as well as moisture susceptibility while maintaining strength and moduli properties. A research study was conducted to understand the strength, resilient, and ductile behaviors of sandy soils treated with cement and a combination of cement and vinyl acetate ethylene (VAE) copolymer. Engineering tests such as unconfined compressive strength (UCS) and resilient modulus tests were conducted on both control and treated soil specimens cured for 7 days. Tests were conducted on specimens before and after immersing in water bath for 4 h to investigate the moisture susceptibility. In these tests, an increase in UCS was observed after cement and cement-VAE treatments as compared to control soil specimens. Results showed that cement-VAE-treated soils exhibited an increase in the axial strain at failure, indicating the semiductile behavior compared to cement-treated specimens. An improvement in the resilient moduli was observed after treatments. Subsequently, two of three-parameter models were used to analyze resilient modulus formulations with stress conditions and determined the regression constants. In conclusion, the study revealed that the use of VAE copolymer improved the stress-strain responses of cement-treated soils and imparted closer to the semiductile behavior, which will reduce cracking in overlying pavement structures. [ABSTRACT FROM AUTHOR]

The microscale mechanisms underlying the suction anchor–sandy soil interaction under slidable pulling actions of mooring lines remain poorly understood. This technical note addresses this knowledge gap by investigating the suction anchor–sandy soil interaction from micro to macro, with a particular emphasis on the effect of interface friction. The discrete element method (DEM) was utilized to simulate the sandy soil, while the finite element method (FEM) was employed to model the suction anchors. The peak pulling forces in numerical simulations were verified by centrifuge test results. The research findings highlight the significant influence of interface friction on the pulling force–displacement curves, as it affects the patterns of suction anchor–sandy soil interactions. Furthermore, clear relationships were established between the magnitude of interface friction, rotation angle, and pullout displacement of suction anchors. By examining the macro-to-micro behaviors of suction anchor–sandy soil interactions, this study concludes with a comprehensive understanding of failure patterns and their key characteristics under different interface friction conditions. The findings proved that the interface friction not only influences the anti-pullout capacity but also changes the failure patterns of suction anchor–soil interactions in marine engineering. [ABSTRACT FROM AUTHOR]

Geogrid reinforcement has a limiting effect on the lateral deformation and thus improves the shear strength of the soil, the overall strength of the soil and the overall stability of the corresponding geotechnical structure. In this study, large-scale triaxial tests without and with geogrid reinforcement were conducted on three typical gravelly soils in Xinjiang using a large-scale triaxial apparatus. The shear strength and deformation characteristics of gravelly soils with different particle shapes and the stress-strain relations, strength characteristics, damage patterns, and reinforcement effects of gravelly soils with and without reinforcement were investigated. Geogrid reinforcement effectively enhances the strength of the soil; the internal friction angle remained relatively constant with and without reinforcement, whereas the cohesive force increased significantly. The reinforcement effects interpreted from the results obtained from the triaxial tests were discovered when a certain deformation or relative displacement with the reinforcement materials of the soil occurred. Under uniform test conditions, the volumetric strain of the samples of gravelly soil with reinforcement significantly decreased with increasing confining pressure, and the difference in volumetric strains with and without reinforcement was greater when the confining pressure was higher. The highlight of this study is its significance in explaining the reinforcement mechanism in gravelly soils and in selecting engineering design parameters. [ABSTRACT FROM AUTHOR]

The investigation of soil is a particularly important stage of structural design. Cone penetration tests (CPTs) are the most common soil investigation techniques. The results of these tests provide information about the values of cone resistance (qc) and sleeve friction (fs), which correspond to depth. Previous studies have shown that the ratio of sleeve friction to cone resistance depends on the particle size distribution in soil and its use for soil classification. Unfortunately, as an analysis of the literature shows, there is no such classification for coarse-grained soils. This paper presents statistically significant differences in the ratio of fs to qc in coarse-grained soils. Based on the research performed, the proposed coefficients depend on the classification of coarse-grained soils with respect to the size of the soil particles. The data investigated were obtained from study reports on 35 sites (5934 tests) at which the main type of soil was coarse-grained and contained different sizes of particles. Following a statistical analysis, five groups of tested coarse-grained soils, silty fine sand, clayey fine sand, fine sand, medium sand and gravelly coarse sand together with gravel, are derived. The analysed data show statistically significant differences in the ratio of fs to qc considering this particular type of soil. A ratio of fs to qc with a probability of 95% is proposed for sandy soils. The values for silty fine sand, clayey fine sand, fine sand, medium sand and gravelly coarse sand mixed with gravel are 0.009459, 0.010982, 0.009268, 0.008001 and 0.006741, respectively. A linear relationship between the fs and qc indexes is also suggested. [ABSTRACT FROM AUTHOR]

A new model was first proposed to estimate the ultimate bearing capacity of strip foundations under transient flows on the basis of the kinematic approach of limit analysis. To describe the collapse process, a symmetrical collapse mechanism was generated by discretization technique following the associated flow rule. A layer-wise summation method was developed to calculate the internal dissipation rate. The theoretical results of this paper are given in terms of some assumptions: (1) both soils and fluids considered in this study were regarded to be noncompressible; (2) the hydraulic conductivity in an unsaturated state was equal to that in a saturated state; and (3) the slope of the soil–water characteristic curve was assumed to be constant through the whole transient infiltration process. A series of comparisons with the theoretical results and experimental data were established to verify the reliability of the new approach proposed by this paper. Based on the numerical results and discussions, the key conclusion can be drawn as follows: the ultimate bearing capacities saw a relatively large decrease under transient flows, especially for strip foundations embedded in silt soil, however, the bearing loads for foundations in sandy soil tended to be steady throughout the whole infiltration process. [ABSTRACT FROM AUTHOR]

The fortification system of the tunnel structure spanning the active fault, such as the failure mechanism and fault-resistant design (measures), has not been thoroughly established. In this study, the self-developed cross-fault large-scale bedrock dislocation loading device platform is utilized to carry out the model test of the tunnel structure and soil site of sand and cohesive soil when the low-angle reverse fault dislocation occurs, based on the earthquake damage. The results demonstrate that: (1) When the fault is staggered, the segmented flexible joint tunnel segment is more favorable in the cohesive soil site. (2) When compared to the cohesive soil tunnel structure site, the strain change of the tunnel structure in the sandy soil site is greater, with the vault increasing by roughly two times and the arch bottom increasing by nearly six times. After the tunnel is buried, the uplift range of the sand cover layer grows, revealing uneven deformation, and the rupture zone migrates to the footwall; hence, the sand site plays a "add seismic" role in the cross-fault tunnel structure. (3) Knowing the location and shape of the rupture range of the overburden soil caused by bedrock dislocation under different inclination angles and soil properties is required in the design in order to place the buried depth and segment length of the tunnel reasonably and take fault-resistant measures. [ABSTRACT FROM AUTHOR]

Biological soil crusts (BSCs) are common in arid and semi-arid ecosystems and enhance soil stability and fertility. Highway slopes severely deplete the soil ecological structure and soil nutrients, hindering plant survival. The construction of highway slope BSCs under human intervention is critical to ensure the long-term stable operation of the slope ecosystem. This study investigated the variation rules and interaction mechanisms between soil nutrients and microbial communities in the subsoil BSCs on highway slopes. Bacterial 16S rRNA high-throughput sequencing was employed to investigate the dynamic compositional changes in the microbial community and perform critical metabolic predictive analyses of functional bacteria. This study revealed that the total soil nitrogen increased significantly from 0.557 to 0.864 g/kg after artificial inoculation with desert Phormidium tenue and Scytonema javanicum. Actinobacteria (44–48%) and Proteobacteria (28–31%) were the dominant phyla in all samples. The abundance of Cyanobacteria, Cytophagaceae, and Chitinophagaceae increased significantly after inoculation. PICRUST analysis showed that the main metabolic pathways of soil microorganisms on highway slopes included cofactor and vitamin, nucleotide, and amino acid metabolisms. These findings suggest that the artificial inoculation with Phormidium tenue and Scytonema javanicum could alter soil microbial distribution to promote soil development on highway slopes toward nutrient accumulation. [ABSTRACT FROM AUTHOR]

Heavy metal contamination in soil due to rapid industrialization has imparted a severe threat to the terrestrial ecosystem. Mining activity has perturbed the fertility and increased the heavy metal concentration in soil. Here we explore an inexpensive and environmentally friendly tool, biosurfactant to restore edaphic factors. Here, we have synthetically prepared contaminated sandy soil and black cotton soil with zinc and investigated the potential of biosurfactants in decontaminating zinc (Zn) from soil samples (sandy soil and black cotton soil). The biosurfactant (64 dynes/cm) was produced by bacillus subtilis MTCC 2423 on an unconventional substrate (20% distillery spent wash) and used as a tool to decontaminate zinc (heavy metal) from soil. The column experimental study was performed to evaluate the heavy metal removal efficiency of the biosurfactant. Statistical tool, Box-Behnken design (BBD) with an artificial neural network linked genetic algorithm (ANN-GA) was adopted to optimize the three independent variables viz., pH, biosurfactant concentration (%), and heavy metal (Zn) concentration. Results reveal that the decontamination efficiency of biosurfactant varied from soil to soil. Highest efficiency was observed in sandy soil compared to black cotton soil. Maximum efficiency of 89.11% was achieved with an optimal level of pH = 5, biosurfactant concentration = 100%, and Zn concentration = 2750 ppm in sandy soil. Whereas a maximum of 36.03% of zinc was removed in black cotton soil with pH, biosurfactant, and zinc concentrations of 7, 55%, and 500 ppm, respectively. [ABSTRACT FROM AUTHOR]

With the expansion of reserve cultivated land resources in coastal saline–alkali areas, the problem of soil salinization is becoming more and more prominent. In order to reveal the influence of different soil media and contact modes on soil water movement, a two-domain Hydrus-3D model was established to verify its performance in heterogeneous soil layers, and the characteristics of water, salt, and wet peak transport of surface soil and sandy soil under horizontal contact and inclined contact conditions were analyzed through experiments and simulations. The measured data show that in horizontal contact mode, probe 3 and probe 2 are close to the interface of the two layers of soil, and their maximum values are measured in about 60 min. The time difference between probe 1 and probe 2 is about 15 min. In the inclined contact mode, probe 4 in the topsoil reached 45% in 10 min and remained stable; the peak lag time of probes 3 and 2 was 10 min, and the peak lag time of probes 2 and 1 was 15 min; the water in the surface soil gradually increases and then stabilizes; and the water in the sand soil is similar to the normal curve. The salt characteristics in the surface soil are similar to the normal curve, while the salt characteristics in the sandy soil gradually increase and then stabilize. The simulation results show that the water content in the topsoil is more than 40%, and the maximum water content in the center of the sand is only 36.9%, which is roughly the same as the experimental results. The results showed that the Hydrus-3D model had a good simulation effect on the groundwater salt transport of heterogeneous soil under two contact methods. The RMSE value and E value are close to 0 and 1, respectively, indicating that the simulation has good feasibility and can be applied to the simulation of water and salt transport processes under different contact modes of soil media. [ABSTRACT FROM AUTHOR]

To evaluate the effects of biochar on pH buffering capacity (pHBC) of paddy soils, rice straw biochar (RC) was modified by hydrogen peroxide (H2O2) and nitric acid/sulphuric acid (HNO3/H2SO4), respectively, and then added to the paddy soils developed from sandy Ultisol, clay Ultisol and granite Ultisol at the same proportion. After submerging and draining incubation, soil pHBC, soil pH and the available cadmium (Cd) extracted with calcium chloride were determined. The results indicated that the two modified biochars effectively promoted pHBC of three paddy soils and HNO3/H2SO4 modified biochar (HNO3/H2SO4-RC) led to greater increase in soil pHBC. Compared with control, HNO3/H2SO4-RC apparently increased pHBC of the paddy soils from sandy Ultisol, clay Ultisol and granite Ultisol by 32.7%, 37.4% and 25.3%, respectively. Correspondingly, soil pH increased by 1.59, 1.15 and 0.88 units, and the available Cd decreased by 74.1%, 67.5% and 75.0% in the paddy soils due to the incorporation of HNO3/H2SO4-RC. HNO3/H2SO4 modification significantly increased the carboxyl groups on the surface of RC. The dissociation of these functional groups produced a large number of organic anions, which could consume exogenous protons, and thus retarding the decline of soil pH and decreased soil available Cd. [ABSTRACT FROM AUTHOR]

The purpose of this work is to identify rocky, sandy, and surface-calcareous soils, using a multi-zonal satellite image, in the south of the Volga Upland in Volgograd oblast. The object of the study is the Volga–Don irrigation system within the Oroshaemaya Experimental Station. The interpretation has been performed by the spectral brightness of the space image (Pleiades) of the bare soil surface in four spectral bands. The most ranked values among them are detected in band B1 (0.43–0.55 μm). Terrain information about soils has been obtained on three catenas. It has been found that the greatest brightness (B1) is created by stones, crushed stone, and sand scattered on the surface (970–1100 units). They are followed by soils, effervescing from the surface, with strongly gravelly rocks at a depth of about 1.5 m and sandy loamy soils (710–830 units); by soils, effervescing from the surface, on mottled loams and sands at a depth of about 0.5 m (to 700 units); and by surface-calcareous soils, where mottled loams and sands are more than 70 cm deep, or calcareous material is absent in the surface horizons (560–670 units). The use of this approach will enable more detailed interpretation of soils by satellite imagery materials and discriminating the surface-rocky and sandy soils and the surface-calcareous ones. They are reflected by a similar spotty pattern on images, but differ in spectral brightness. [ABSTRACT FROM AUTHOR]

Untreated surfactant-rich greywater is uncontrollably discharged into the environment in underdeveloped countries and even in some areas of developing countries, which may change soil characteristics. However, there is hardly any research concerning geotechnical behavior of soils contaminated by surfactant. The present study investigates mechanical properties of two types of surfactant-contaminated sandy soils experimentally. Soil samples were collected from Bam County and Shahriar County located in the central parts of Iran. The clean specimens were contaminated by a series of prepared surfactant-rich aqueous solutions containing different amounts of a widely used detergent. The weight ratio of detergent to water was selected equal to 1/20, 1/15, 1/10, and 1/5. Physical characteristics of the contaminant solutions were examined by performing surface tension and viscosity tests. Additionally, geotechnical behavior of the clean and the contaminated samples was investigated through conducting compaction and direct shear tests. Results indicated that the geotechnical properties of the contaminated soils declined by increasing the surfactant concentration in the contaminant. Compared to clean specimens and at the highest contamination level, the optimum water content of both Bam and Shahriar soils reduced from 7.70% and 11.00% to 4.05% and 6.75% as well as the maximum density decreased from 17.87 kN/m3 and 18.52 kN/m3 to 17.37 kN/m3 and 17.88 kN/m3, respectively. Moreover, Bam and Shahriar soils with a maximum degree of contamination showed a reduction in the friction angle from 23.06° and 20.52° to 10.52° and 12.17° as well as a decrease in the formed apparent cohesion of the unsaturated samples by near 56% and 78%, respectively. [ABSTRACT FROM AUTHOR]

Many structures like slabs are usually in contact with soil grades and such case made an interaction in the behavior between the soil and the slab. Gypsum may find randomly in the sandy soil and it may melt when exposing to water. Resolving gypsum forms many hidden voids inside the soil media and these cavities effect in the first degree on the ultimate capacity of concrete slabs. The present study discussed the effect of cavities forming in soil media on the concrete slab which rest on it. The study is an essential topic to understanding how the stresses develops from slab to the soil media, how could the transporter stresses have affected by cavities inside the soil, the influence of cavity and its size and shape on the slab failure capacity. The investigation involves discussing cavity shape, continuity, size, depth, eccentric loading, locations and study the case of cavity filling with stiffer material. It was concluded that, the circular cavity is the best shape because it distributes the stresses best than the other regular shapes. The nearest cavity and the larger cavity size deteriorated the concrete slab capacity due to weakness the concrete supporting. [ABSTRACT FROM AUTHOR]

Today, with the application of nanomaterials in the various branches of science and engineering fields, some researches assessed how nanoparticles affected the geotechnical characteristics of soil. Based on the collection of information from the results of previous studies, the purpose of this review article is to introduce the nanomaterials used in the geotechnical engineering and their application in the problematic soils. In this paper, the modification of the engineering properties of the clay, the sand, the collapsible soil, the soil with liquefaction potential and the soil subjected to the freeze-thaw cycles by nano materials are evaluated. The results of previous researches have shown that the nano materials can increase the resistance properties of the problematic soils. The nano materials improve the soil behavior by two mechanisms such as filling the soil voids, which increases the soil density and improves the frictional resistance of the soil as well as the improvement in the soil particles bonds, which increase in the soil integrity. The results show that the addition of nano materials to clay can lead to an average increase in strength of more than 100% and in sandy soils less than 100%. Also, the optimum content of nanomaterials for decrease in the collapsible potential was approximately 0.1%. [ABSTRACT FROM AUTHOR]

The application of copolymer hydrogels based on acrylamide (AAm) and acrylic acid (AA) in sub‐Saharan soils can increase the quantity of water retained by the soil and improve plant establishment and growth. The aim of this work was to synthesize and characterize a copolymer based on acrylamide and acrylic acid and to evaluate its swelling capacity with different physicochemical parameters. This study also aimed to investigate the effect of metallic cations on the swelling capacity of the copolymer and to assess the improvement in water retention in sandy soils. The copolymer material was prepared by free‐radical polymerization in aqueous solution at a temperature of 60°C and characterized by Fourier transform infrared (FTIR) and x‐ray diffraction (XRD), and its average molecular weight was estimated from intrinsic viscosity measurements. The swelling capacity was evaluated with different physicochemical parameters, and the effect of metallic cations on the swelling capacity was investigated. Water retention in two sandy soils was also evaluated. The copolymer material containing 50% AAm and 50% AA can retain more than 8100% of water. The swelling ratio increased with increasing temperature, with a maximum swelling ratio at 65°C. The presence of metallic cations reduced the maximum swelling ratio of the copolymer material as the cation concentration increased. The copolymer material at 1% in a composition with the soil showed an improvement in the water retention of 12.2% and 7.9% for soil A and 7.9% for soil B. Soil air volume is improved by 19% for both soils. This study shows that the copolymer material has a high swelling ratio and can improve water retention in sandy soils. The copolymer can be used in agriculture to protect and improve plant growth and yield. Highlights: Synthesis and characterization of a copolymer based on acrylamide and acrylic acid.Evaluating the swelling capacity with different physicochemical parameters.The application of this copolymer in sub‐Saharan soils increases the quantity of water retained.The copolymer is prepared by polymerization in aqueous solution and characterized by FTIR and XRD.This study shows that the copolymer has a high swelling ratio and improves water retention. [ABSTRACT FROM AUTHOR]

Soil microorganisms play crucial roles in maintaining material circulation and energy flow in desert ecosystems. However, the structure and function of soil microorganisms in different forestlands are currently unclear, restricting the use of sand-fixing plants and the understanding of forest ecosystem functions. In this study, Artemisia ordosica, Caragana korshinskii, and Salix psammophila, three types of sand-fixing forests widely distributed in the Mu Us Sandy Land, were used to explore the effects of sand-fixing forests on soil physicochemical properties, soil enzyme activity, soil microbial biomass, microbial community structure, and inter-microbial species relationships. Soils of forestlands showed higher soil organic carbon (SOC), total phosphorus (TP), and total nitrogen (TN) contents than bare sandy land. The SOC in bare sandy soil was only 0.84 g kg−1, while it remained 1.55–3.46 g kg−1 in forestland soils. The TN in bare sandy land soil was 0.07 g kg−1, which was significantly lower than that in forestland soils (0.35–0.51 g kg−1). The TP in bare sandy soil was 0.18 g kg−1, significantly lower than that in forestland soils (0.46–0.69 g kg−1). Afforestation of bare sandy land improved soil microbial carbon and nitrogen contents and increased microbial enzyme activities of acid phosphatase and N-acetyl-β-D-glucosaminidase. Significant differences were observed between the three forestlands and bare sandy land in terms of soil microorganisms and community composition. With the establishment of a sand-fixing forest, the alpha diversity of soil bacteria significantly improved, whereas that of soil fungi remained stable. The bacterial community comprised 33 phyla, 106 classes, 273 orders, 453 families, and 842 genera. While five fungal phyla were detected by OTUs at a similarity of 97%, bacterial and fungal community structures were affected by the organic carbon content, sand particle content, soil pH, total nitrogen, and total phosphorus contents of soils. This study is helpful for vegetation construction and protection on sandy lands from the perspective of plant-microbe interactions. [ABSTRACT FROM AUTHOR]

As a natural environmental medium, soil has a wide range of sources and is often used as a material for building houses. It can also be used to construct simple protective structures in actual battlefield environments. In order to study the protective effect of sand on prefabricated fragments in practical situations, the authors conducted experiments on spherical tungsten alloy prefabricated fragments penetrating into sand using sand as the target medium. Natural sand (naturally generated rock particles with a particle size less than 4.75 mm) was selected as the sand, and the initial velocities of the fragments were 689 m/s~1761 m/s (fragment diameter 6 mm) and 596 m/s~1325 m/s (fragment diameter 11 mm), respectively. Based on the residual velocity of fragments and experimental phenomena in experimental data, the authors used LS-DYNA software to numerically simulate and compare the residual velocity of fragments and obtained a numerical model for sandy soil media and a calculation formula for the residual velocity of spherical fragments. Based on modeling equivalence in practical environments, the authors studied the impact of different attack angles on fragment trajectory deviation and found that fragments have the highest deviation values at 20° and 70° attack angles. They also analyzed the soil boundary effect within a small scale range, and the effect was significant when the vertical distance was less than 40 mm. The penetration resistance of different thicknesses of soil was calculated, and the maximum soil thickness under prefabricated fragment penetration at different speeds was obtained. The effective protective size of the soil under actual conditions was about 550 mm. This experiment provides a reference for the construction parameters of simple soil defense structures in actual environments. [ABSTRACT FROM AUTHOR]

Xanthan gum (XG) is an effective soil-binding material for enhancing the geotechnical engineering performance of soil. Due to the hydrophilicity of XG, however, its ineffectiveness as a soil-strengthening agent in wet conditions and the associated durability concerns continue to be obstacles to the implementation of XG soil treatment. Here, we investigated the effect of trivalent chromium (Cr3+) crosslinking on the rheology of XG hydrogels, and consequent variations in the unconfined compressive strength of XG–Cr3+-treated soil. Rheological tests revealed that the crosslinking of Cr3+ initially increased the yield stress of the XG gel; as the gel cured, the XG–Cr3+ gel lost its viscoelasticity and became stiffer and more elastic. With increased Cr3+ and XG concentrations, the time-controllable gelation enhanced the unconfined compressive strength of the sandy soil in a hydrated state. Furthermore, the crosslinking of XG and Cr3+ reduced the swelling of the XG gel and increased strength durability of XG–Cr3+-treated soil under prolonged saturation conditions. Due to the fact that Cr3+ crosslinking effectively improved the wet strength and durability without additional dehydration or heat treatment, this method can expand the applicability of XG soil treatment, such as injection grouting or backfill material for various geotechnical engineering structures. [ABSTRACT FROM AUTHOR]

Cover cropping is a best management practice that can improve soil quality by reducing soil erosion, building soil organic matter (SOM), and improving soil nutrient availability. Southwest (SW) Florida citrus growers have the challenge of growing citrus in sandy soils characterized by low organic matter (<2%), extremely low water and nutrient-holding capacities, and high sand content (>90%), and therefore are looking for methods to improve SOM and nutrient retention and availability in sandy soils. A trial of two cover crop (CC) mixtures planted in the row middles (RM) of Huanglongbing-affected citrus 'Valencia' (Citrus sinensis (L.) Osbeck) orchards in sandy soils in SW Florida was conducted. This study explored how incorporating CCs in the RM of the orchards could affect soil ammonium (NH4+), soil nitrate (NO3−), exchangeable macronutrients, and SOM temporal availability. These parameters were measured under the tree canopy (UC) and within RM of two orchards: South Grove (SG) and North Grove (NG), both located in SW Florida. The two seeded CC mixtures were legume + non-legume (LG+NL) and non-legume (NL) and were compared to a control no-CC grower standard (GSC). Phosphorus, calcium, magnesium, and NH4+ were not statistically significantly different among treatments in either of the two sampling positions (UC and RM). Cover cropping significantly (p < 0.05) increased NO3−-N concentrations in the RM area of the citrus orchards after seven consecutive seasons (brassicas, legumes, and grasses) by 31% in the LG + NL and 29% in the NL with reference to the GSC. In addition to the significant increase in NO3−N, SOM significantly (p < 0.05) increased in the RM in the NG site only in both CCs treatments by 17% and 16% for LG + NL and NL treatments, respectively, compared with GSC. [ABSTRACT FROM AUTHOR]

The performance of passive battered piles resisting the embankment-induced lateral soil movements may differ from that of the active battered pile and axially loaded existing vertical piles adjacent to embankment constructions. This study was part of a preliminary feasibility investigation for a reinforcement plan of an actual embankment project, aiming to experimentally investigate the performance of passive battered piles under embankment-induced lateral soil movement. To this end, a sequence of reduced-scale model tests of battered piles near the surcharges was first designed in sandy soil with a similarity ratio of 1:30. The effects of pile inclinations (β = −20°, −10°, 0°, +10°, and +20°), surcharge magnitudes, and constraint conditions at the pile tip (free-tip and fixed-tip) on the responses of passive battered piles were explored. Finally, the response characteristics of battered piles resisting the embankment-induced lateral soil movement were analyzed to clarify the working mechanism of these battered piles. [ABSTRACT FROM AUTHOR]

We studied the features of PAHs extraction by QuEChERS in the sample preparation of soils and bottom sediments of various compositions followed their determination by gas chromatography–mass-spectrometry. The test samples were soils of sandy, loamy sand, loamy, and clayey types and bottom sediments of loamy sand type. The mineralogical composition and organic matter content of the samples were used to predict how PAHs were retained by the soils and sediments. The impact of ultrasonic treatment on analyte extraction with subsequent identification by chromatography was assessed. No ultrasonic treatment was required to extract and determine all PAHs (up to 100%) in sandy and loamy sand soils and low-molecular-weight PAHs in all test samples. The QuEChERS extraction and determination of high-molecular-weight PAHs in clay type soil samples and loamy sand bottom sediments required a 10-min ultrasonic treatment, while the recoveries of analytes were higher than 87 and 90%, respectively. The analysis of a loamy soil sample with a high organic matter content was the most challenging. To extract over 70% of high-molecular-weight PAHs from a sample of this type using the QuEChERS technique, the binary acetonitrile–acetone (1 : 1) extractant rather than conventional acetonitrile was used with the simultaneous 15-min ultrasonic treatment. [ABSTRACT FROM AUTHOR]

In an anchor support system, once the soil strength is improved by grouting with a geotextile, the pull-out force of anchors increases. To investigate the improvement of surrounding soils due to the grouting with a geotextile, a series of filtration and penetration tests under various parameters such as different initial degrees of compaction, water content and soil types were conducted via a self-developed device. In addition, microscopic tests were then carried out to obtain the soil's structure before and after grouting. The main conclusions are as follows: (1) The strength of surrounding soils is improved by grouting with a geotextile through the compaction effect and the slurry infiltration, while its strengthening effect gradually declines with the increase in the initial degree of compaction. (2) As the initial water content increases, the strengthening effect derived from the compaction effect and the cohesive substances infiltration decreases, while this improved efficiency of the soil strength declines due to the water infiltration during grouting. (3) Although the effect of grouting with a geotextile on different soils is obviously different due to the different efficiency of slurry (i.e., water and cohesive substances) infiltration, it can improve the soil strength regardless of soil type, especially for sandy soils. (4) Under the filtration of geotextile, a hardened layer is formed at the grout–soil interface due to the accumulation of cohesive substances, which is beneficial to the performance improvement in applications such as the capsule-type anchor. [ABSTRACT FROM AUTHOR]

Soil shear strength is the most fundamental property when designing structures in the ground and should be carefully assessed and understood. Several empirical models were introduced to predict the shear strength of unsaturated soils. However, there is uncertainty regarding the applicability and sensitivity of these prediction models. This paper presents a comprehensive verification study to assess the reliability and validity of the existing theoretical models. The results obtained from the prediction models are compared to measured data using thirty experimental data sets. A performance classification program is also conducted to assess the suitability of the analytical models for different soil types as well as over a wide range of matric suctions, saturation degrees, soil densities, soil plasticity, and clay activity. The impact of each single parameter is clarified by the microstructure studies, which also provides insight into the mechanics of unsaturated soils. The results indicated that the applicability of models is more appropriate for sandy soils rather than for clayey ones. The performance of shear strength models tends to decrease with an increase in matric suction, initial density, plasticity index, and clay activity. It is, therefore, recommended that the shear strength estimation models should be carefully selected depending on the soil type and properties. Besides, the analysed results pointed out that the choice to assume the factor χ in the equation of Bishop equals the saturation degree is only suitable for medium-dense soils with low matric suction. This assumption is particularly not effective for clayey soils, or dense soils with high matric suction. [ABSTRACT FROM AUTHOR]

For high yield peanut in Northeast Agro-pastoral Ecotone, topdressing ratios of NPK fertilizer (pure N 68.18 kg/hm², P 22.08 kg/hm², and K 174.33 kg/hm²) were used in 6 treatments for investigation of NPK effects. The field experiment was conducted under mulch drip irrigation. Nutrient and enzymatic activities of sandy soil and peanut yield were detected to clarify the optimal basal/topdressing ratio. Results showed that the content of soil organic matter and available N, the activity of urease and sucrase were both increased with the topdressing ratio, while the thicker the soil layer, the lower its content and activity were. The peanut yield was increased firstly and then decreased with the topdressing ratio, which was higher than the traditional fertilization method. The two-year peanut increasing yield range was 3.77%-41.27%. Yields reached the highest at T60, as 6427.7 kg/hm² and 6046.8 kg/hm² respectively. When all of the NK fertilizers were used as topdressing, the yield was not increased obviously, which was average 4.53% higher in two years. In summary, it had the best effect with 40% of the total fertilization amount used as the base fertilizer, and 60% used as topdressing under water and fertilizer integration measures in the area. [ABSTRACT FROM AUTHOR]

Soil tolerance towards contamination with platinum nanoparticles (PtNP) was assessed using biological parameters for soils of southern Russia differing in particle-size composition, organic matter content, and soil reaction. Model laboratory experiments were performed with samples from the upper (0–10 cm) layer of soils with contrasting genetic characteristics, i.e., ordinary chernozem (Haplic Chernozem (Loamic)), brown forest soil (Eutric Cambisol), and gray sandy soil under pine stand (Eutric Arenosol). PtNP concentrations of 0.01, 0.1, 1, 10, and 100 mg/kg were studied. Soil tolerance was estimated using sensitive and informative biological indices: the total number of bacteria, the activity of catalase and dehydrogenases, and germination degree of radish seeds, and radish root length. In most cases, low PtNP concentrations (0.01, 0.1, and 1 mg/kg) did not affect reliably the biological state of soils, whereas higher doses (10 and 100 mg/kg) worsened biological characteristics. The enzymatic activity of PtNP-contaminated soils decreased to a lesser extent than the phytotoxic and microbiological indices. Ordinary chernozem showed a higher tolerance towards PtNP contamination than brown forest soil and gray sandy soil. The results of this study can be used for predicting ecological risks of soil contamination with PtNP and for assigning the maximum permissible concentration for platinum in different soils. [ABSTRACT FROM AUTHOR]

In this paper, a constitutive model is presented to model the behavior of various soils (sand and clay) in different loading conditions and the minimum required parameters are obtained. Although some practical features (concepts) of the bounding surface framework and modified Cam-Clay have been employed in its formulations, the model is developed mainly based on the generalized plasticity framework. Moreover, some concepts such as dilatancy relation and loading history surface are redefined. Finally, the proposed constitutive model is evaluated using the experimental data related to two different sandy soils and three different clays under different loading conditions. Finally, it is concluded that the proposed constitutive model can easily be calibrated for various clayey and sandy soils. It can depict different behavioral aspects of these soils under different monotonic and cyclic loading conditions. [ABSTRACT FROM AUTHOR]

Cyperus esculentus is considered the sixteenth worst weed in the world. The weed causes huge losses in arable crops. Current control strategies are based on combinations of chemical and mechanical methods, repeated over years, and aim to deplete the belowground bud bank. However, this is a slow process. Anaerobic soil disinfestation (ASD) using readily decomposable carbon sources may be a promising innovative method to quickly deplete the bud bank. This study investigated the effect of ASD with fresh grass clippings (dosage of 80 tonnes ha−1) differing in C:N ratio and Herbie® (consists of organic by-products from the food processing industry, dosage of 25 tonnes ha−1) on the vitality of small and large C. esculentus tubers buried at three depths (5, 15, and 30 cm) into two soils differing in soil type and soil moisture content. Their effects were compared with the effect of chemical soil disinfestation (CSD) with metam-sodium (153 kg ha−1). ASD with Herbie® showed at least equal performance compared with CSD with metam-sodium, with reductions in tuber vitality up to 97.5%. The performance of ASD with grass clippings was less consistent across soils and was affected by the C:N ratio of the grass. Both ASD and CSD showed the highest performance in moist, sandy soil and on small tubers. ASD is an effective and promising method to quickly deplete the C. esculentus bud bank, provided that the soil is sandy and moist, the carbon source has a C:N ratio of about 10, and the incorporation depth is at least 25 cm. To foster the implementation of ASD, future research should evaluate its performance consistency across environments and years. [ABSTRACT FROM AUTHOR]

In this paper, ground granulated blast furnace slag, steel slag, red mud, waste ceramic powder, and desulfurization gypsum were used as raw materials to develop a kind of multi-source solid-waste-based soft soil solidification material. Three ratios and the strength activity index were used to determine the fractions of different solid wastes. The mineralogical and microstructural characterization was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis–differential scanning calorimetry (TG&DSC) tests. The results showed that the unconfined compressive strength of the three types of soft soil increases with an increase in the content of the solidifying agent. The failure strain of the stabilized soil decreases from 1.0–1.3% to 0.75–1.0%, and the failure mode gradually changes from plastic failure to brittle failure. The optimum content of the solidifying agent was determined to be 17% (the lime saturation factor (KH), silica modulus (SM), and alumina modulus (IM) of the solidifying agent were set to 0.68, 1.74, and 1.70, respectively), and the unconfined compressive strength (28 d) of the solidified soil (sandy soil, silty clay, and organic clay) was 3.16 MPa, 2.05 MPa, 1.04 MPa, respectively. Both measurements can satisfy the technical requirements for a cement–soil mixing pile, suggesting the possibility of using various types of solid waste as a substitute for cement. [ABSTRACT FROM AUTHOR]

Organic amendments (OAs) can improve the hydro‐physical properties of a soil and thereby potentially enhance the resilience of agricultural systems to droughts and floods. An OA's contribution to this resilience, however, depends on the timeliness of its impacts, as soil improvements should be achieved when droughts are most frequent or flood risks are greatest. Yet little is known regarding the temporal variability of OA impacts or the influence of OA quantity and quality thereupon. In this research, therefore, we investigated at two agricultural sites the temporal variability of improvements in soil bulk density, aggregate stability, infiltration capacity and water retention after the application of compost, farmyard manure, bokashi, a selection of organic residues from landscape maintenance, and a combination of these residues with manure. Results showed that, depending on management practices and soil type, OAs decrease bulk density by up to 9.8%, increase infiltration capacity by up to 108.1%, aggregate stability by up to 60.0%, and water retention by up to 77.8% relative to unamended controls within 3 years of repeated application. However, the magnitude of these improvements varies up to 96% between seasons, depending on the soil property and OA treatment. On average, for all treatments, impacts relative to the control varied between different seasons by 5% for bulk density, 47.1% for infiltration capacity, 22.6% for aggregate stability, and 26.3% for water retention. When offsetting OA nutrient differences with mineral fertilizers, this variability showed a stronger correlation to differences in OA application quantity than quality (i.e., chemical composition). Results suggest that disregarding temporal variability in OA impacts can result in an inaccurate valuation of OAs as either effective or ineffective in improving soil resilience, given that impacts may, instead of their frequently presumed persistency, actually be highly transient or lagged. Our findings highlight the importance of considering the potential intra‐annual variability of OA impacts on soil hydro‐physical properties when designing OA application strategies to ameliorate the effects of specific seasonal climatic challenges. Core Ideas: Hydro‐physical properties improved within 3 years of repeated organic amendment (OA) application.Improvements were more closely related to OA application rates than to OA composition.The impact of OAs on hydro‐physical properties showed significant temporal variability.Temporal variability in OA impacts was influenced by soil type and land management practices.No single OA quantity or qualitative property could consistently explain the observed temporal variability. [ABSTRACT FROM AUTHOR]

Organic fertilization and mycorrhization can increase the phytoremediation of copper-contaminated soils. The time of vermicomposting alters the properties of vermicompost, which can affect copper's availability and uptake. Therefore, this study sought to evaluate the effect of different organic fertilizers and mycorrhization on copper-contaminated soil phytoremediation. The soil was contaminated with 100 mg Cu kg−1 dry soil and received mineral fertilizer (MIN), bovine manure (CM), and vermicompost produced in 45 days (V45) or 120 days (V120), all in doses equivalent to 40 mg kg−1 dry soil of phosphorus. Half of the jack bean (Canavalia ensiformis) plants were inoculated with the arbuscular mycorrhizal fungus Rhizophagus clarus. At plant flowering, the dry mass and concentrations of Cu, Zn, Mn, Ca, Mg, P, and K in the soil, solution, and plant tissue were determined, in addition to mycorrhizal colonization, nodulation, photosynthetic pigments, and oxidative stress enzyme activity. Organic fertilization increased plant growth and copper accumulation in aerial tissues. These effects were more evident with the V120, making it suitable for use in copper phytoextraction. Mycorrhization increased root and nodule dry mass, making it recommended for phytostabilization. C. ensiformis nodulation in Cu-contaminated soils depends on vermicompost fertilization and mycorrhization. Hence, the copper phytoremediation by C. ensiformis is increased by using organic fertilization and mycorrhization. [ABSTRACT FROM AUTHOR]

Detection dogs are increasingly used to locate cryptic wildlife species, but their use for amphibians is still rather underexplored. In the present paper we focus on the great crested newt (Triturus cristatus), a European species which is experiencing high conservation concerns across its range, and assess the ability of a trained detection dog to locate individuals during their terrestrial phase. More specifically, we used a series of experiments to document whether a range of distances between target newts and the detection dog (odour channelled through pipes 68 mm in diameter) affects the localisation, and to assess the ability and efficiency of target newt detection in simulated subterranean refugia through 200 mm of two common soil types (clay and sandy soil, both with and without air vents to mimic mammal burrows, a common refuge used by T. cristatus). The detection dog accurately located all individual T. cristatus across the entire range of tested distances (0.25 m– 2.0 m). The substrate trials revealed that the detection dog could locate individuals also through soil. Contrary to existing studies with detection dogs in human forensic contexts, however, detection was generally slower for T. cristatus under sandy soil compared to clay soil, particularly when a vent was absent. Our study provides a general baseline for the use of detection dogs in locating T. cristatus and similar amphibian species during their terrestrial phase. [ABSTRACT FROM AUTHOR]

Background: This study evaluated the effect of phosphate fertilizer dose, soil type, or both on the growth and yield of maize vegetable in soil with different P content of Southern Vietnam Methods: This research was studied from 2015-2018. Experiment 1 was set up in pots with three phosphorus fertilizer levels and five soil types in a greenhouse at Can Tho University. Experiment 2 was set up at Tra Vinh sandy soil (Dystri-Gleyic-Arenosols). Result: The results showed that in the phosphorus-rich groups, there was no difference in the effect of phosphate dose on the growth and yield of maize vegetable, but there were differences between soil types. Differences in the development and yield of maize between soil types may be due to soil composition and pH. Maize plants adapted and yielded better on sandy soils (Dystri-Gleyic-Arenosols) compared to alluvial (Eutri-Mollic-Gleysols), alkaline (Umbri-Epiorthi-Thionic-Gleysols) and red soils (Hapli-Plinthic-Ferralsols). In addition, the total phosphorus content in fruit-bearing leaves was higher in the phosphorus-rich treatment than in the low phosphorus fertilizer application treatment. Still, no symptoms of excess phosphorus on maize vegetable was detected. [ABSTRACT FROM AUTHOR]

Indonesia is a tropical country threatened by many disasters, such as earthquakes and other collateral hazards (liquefaction). Utilization of micro pile on the liquefaction prone areas is quite popular to increase the soil bearing capacity. In this research, Eucalyptus Pellita Timber was used as micro-piles alternatives. This study aims to determine the effect of timber pile addition on soil settlement and the increase in bearing capacity. Some laboratory investigations were conducted, such as timber and soil physical and mechanical characteristics, preloading tests, and seismic load tests by using small-scale shaking table test. The preloading tests were carried out for 40 days, and the settlements were recorded every 24 hours. Subsequently, seismic load tests were conducted on sandy soil with Dr = 40%. The seismic duration was 37 seconds, with PGA = 0.3 g and f = 0.78 Hz. The preloading test results show that Eucalyptus pellita timber piles are able to reduce the settlement by 18%. and from seismic load testing results are able to reduce the settlement by 68% due to earthquake loads with PGA = 0.3g and a frequency of 0.78 Hz on sandy soil with the potential for liquefaction. This is due to the resistance at the tip of the pile and the skin friction on the timber pile. So, from the results of the model test, it shows that the use of Eucalyptus Pelita timber piles can be used as an alternative to handling sandy soils in areas where liquefaction has the potential to occur. [ABSTRACT FROM AUTHOR]

In most codes of practice for the building and construction, the conventional equations from Meyerhof, Hansen, Vesic, and Terzaghi are all acceptable for the determination of the ultimate bearing capacity of shallow foundation. It is difficult to evaluate which equation has the best performance against the experimental data on different types of soil. The stabilities of all the buildings, utilities, and other infrastructure in the urban area are much dependent on a reliable foundation. As a result, the methodology of the foundation design is important in the urban and rural development. However, in the codes of practice for the building and construction, it does not specify which method is most reliable for the determination of the ultimate bearing capacity of shallow foundation. It is good to understand the uncertainty associated with different equations in the determination of the ultimate bearing capacity. In this study, a total of 163 data sets from the experimental tests conducted on sandy soils were collected from different literatures. The ultimate bearing capacity values calculated using different equations were compared with the experimental data. It was observed that Vesic equation provides the best performance in calculating the ultimate bearing capacity of sandy soils. In addition, a new equation for the estimation of the bearing capacity factor, Nγ, is proposed in this study. The equation was developed using the regression analysis incorporating the collected database. The performance of the proposed equation was verified with independent data sets and presented in the Taylor diagram. [ABSTRACT FROM AUTHOR]

Bioremediation has been proven to be efficient method of cleaning up oil contaminated soils through the application of proper microorganism to contaminated soils. Hence, this research involves the bioremediation of four different types of contaminated soil. The soils were categorized as laterite, sandy soil, clay soil, and loamy soil which are classified technically using American Society for Testing and Materials (ASTM) method as clayey sand, silty sand, clayey sand and poorly graded sand respectively. These soils were contaminated with Bonny light crude oil to the concentration of 33.3 g/l. The soils were inoculated with petroleum remediation microorganisms. Soil samples were taken after 14 and 25 days, and the residual total petroleum hydrocarbon (TPH) was checked using Environmental Protection Agency (EPA) Method 8015. The condition of the soils was kept almost constant during the process by preserving it in an insulated vessel to avoid evaporation of moist or organic gases. The results obtained showed percentage reduction 70%, 69%, 49%, and 26% in hydrocarbon after the period of 25 days in Sand, Laterite, Topsoil and Clay soil respectively. The removal percentage was the highest (70%) for the sandy soil, and the lowest for the clay soil (26%). The result indicate that the particle size distribution of soil affects bioremediation to an extent, since clay with lowest particle size proved more difficult to bio-remediate. [ABSTRACT FROM AUTHOR]

The literature on the presence of microplastics (MPs) and their potential impact on terrestrial ecosystems is still scarce. Interestingly, soil MPs are detected as organic carbon (SOC) using traditional quantification methods (e.g., loss on ignition [LOI]), although its dynamics in the environment will be different. The objective of this study was to quantify the carbon (C) contribution of MPs to the SOC in superficial soil samples from a coastal urban wetland (Avellaneda, Buenos Aires, Argentina) with the features of a humid subtropical forest and compare with hydrocarbon contribution. Soil samples were split for analysis of moisture content; texture (sieve and pipet method); organic matter as a LOI (8 h at 450 °C); total hydrocarbons (THCs; gravimetry of solvent extractable matter); n‐alkanes (solvent extraction and gas chromatography‐flame ionization detection analysis); and extraction of MPs (floatation in NaClaq, filtration, H2O2 digestion, and visual sorting under a stereomicroscope). The superficial soil was a sandy clay loam with a large organic matter content (19%–30%). The THC averaged 2.5 ± 1.9 g kg and the marked predominance of odd‐numbered carbon n‐alkanes maximizing at C29 and C31 show the contribution of the terrestrial plant waxes. The average number of MPs was 587 ± 277 items kg of dry soil, predominantly fibers. Taking account of the C content, THCs and MPs add to the soil 1.23 ± 1.10 ton C ha and 0.10–0.97 ton C ha, respectively. Therefore, in this system with humid forest characteristics, the MPs represent between 0.12% and 1.25% of soil estimated carbon, in a magnitude similar to the C contribution of THCs (0.6%–4.2%). This preliminary study shows the relevance of discriminating MPs from other carbon sources and presents a description of their impact on soils to advance future research or tools for decision‐makers. Integr Environ Assess Manag 2023;19:698–705. © 2022 SETAC Key Points: This work quantifies the contribution of carbon by microplastics to soil and compares it with the contribution of total hydrocarbons.This study shows that for the moderately productive area Reserve Municipal Coast of Avellaneda, with a slow decomposition of leaf litter, microplastics account for between 0.12% and 1.25% of the total estimated carbon of the topsoil.Because of the resistance of microplastic to decomposition, it would be expected to accumulate in the soil and should be taken into account to assess the soil carbon storage function. [ABSTRACT FROM AUTHOR]

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