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• Calibration of red clay with different water contents based on EDEM software. • The Hertz-Mindlin with JKR Cohesion model was used to model red clay soil's physical properties. • Experimental studies provide insights into the impact of soil moisture content on its properties. • Technical references for future research on soil-tool interactions were provided. Distinct physical properties of red clay soil in hilly and mountainous regions of southwest China, including high adhesiveness and density, challenge the operation of agricultural machinery. A scarcity of accurate discrete element simulation parameters for this soil type restricts computational modeling. The study was focused on red clay soil with a moisture content of 12.50% ± 1% and a measured repose angle of 35.54°. The soil's inherent physical properties were identified through experimental assessments. Soil contact mechanical parameters were obtained from the GEMM database, and optimal contact parameter ranges were determined using Steepest Ascent Experiments, with the simulated soil particle repose angle serving as the response value. A second-order regression model was developed using a quadratic regression rotation orthogonal combination test. By taking the actual repose angle as the optimization criterion, parameters were optimized. The optimal contact mechanical parameters in EDEM simulations were identified as: JKR surface energy at 8.981 J/m2, recovery coefficient at 0.474, dynamic friction coefficient at 0.196, and static friction coefficient at 0.45. The model yielded a repose angle of 36.21°, closely corresponding with the observed value, with a relative error of 1.80%. The parameters calibrated in this study offer a valuable reference for future soil-tool interaction studies and tillage implement optimization in these regions. [ABSTRACT FROM AUTHOR]

Advanced hyperspectral remote sensing technology can identify various clay minerals in the soil. The improved spectral and spatial resolution of the airborne hyperspectral sensor can be used for a better interpretation of clay mineral abundance in the soil. This research utilizes the high-resolution image data acquired from Advanced Visible Infrared Imaging Spectrometer Next Generation (AVIRIS-NG) on an airborne platform to map the abundance of clay minerals in the Udaipur region of Rajasthan (24° 34′ 16.5720′' N, 73° 41′ 29.5584′' E). The representative soil samples for various soil clay minerals, e.g., kaolinite, montmorillonite, and illite, were classified from AVIRIS-NG data using a spectral feature fitting algorithm. A total of thirty sites were selected from agricultural and wastelands for soil sample collection. X-ray diffraction (XRD) analysis of representative soil samples was carried out to find the percentage and type of clay minerals present. Regression analysis between absorption peak depth values estimated from the hyperspectral image of the sampling sites in the spectral region from 2205 to 2214 nm and corresponding clay content value showed a significant relationship. The regression line obtained for the known pixels was used to prepare the mineral abundance map over the study area. This study significantly indicates the dominance of montmorillonite clay mineral over kaolinite and illite in the soils of the Udaipur region. [ABSTRACT FROM AUTHOR]

• Montmorillonites reduced GLP and AMPA bioavailability in soil, corn roots and leaves. • Kinetic studies with different concentrations, doses, and duration showed dose- & time-dependency. • Acid processed montmorillonite reduced mixtures in roots by 76% and in leaves by 57%. • Decrease in roots, leaves and soil was consistent and continuous without detectable dissociation. • Montmorillonites can serve as soil supplements to remediate GLP and AMPA in soil. The co-occurrence of glyphosate (GLP) and aminomethylphosphonic acid (AMPA) in contaminated water, soil, sediment and plants is a cause for concern due to potential threats to the ecosystem and human health. A major route of exposure is through contact with contaminated soil and consumption of crops containing GLP and AMPA residues. However, clay-based sorption strategies for mixtures of GLP and AMPA in soil, plants and garden produce have been very limited. In this study, in vitro soil and in vivo genetically modified corn models were used to establish the proof of concept that the inclusion of clay sorbents in contaminated soils will reduce the bioavailability of GLP and AMPA in soils and their adverse effects on plant growth. Effects of chemical concentration (1–10 mg/kg), sorbent dose (0.5%-3% in soil and 0.5%-1% in plants) and duration (up to 28 days) on sorption kinetics were studied. The time course results showed a continuous GLP degradation to AMPA. The inclusion of calcium montmorillonite (CM) and acid processed montmorillonite (APM) clays at all doses significantly and consistently reduced the bioavailability of both chemicals from soils to plant roots and leaves in a dose- and time-dependent manner without detectable dissociation. Plants treated with 0.5% and 1% APM inclusion showed the highest growth rate (p ≤ 0.05) and lowest chemical bioavailability with up to 76% reduction in roots and 57% reduction in leaves. Results indicated that montmorillonite clays could be added as soil supplements to reduce hazardous mixtures of GLP and AMPA in soils and plants. [Display omitted] [ABSTRACT FROM AUTHOR]

• BHET treatment formed a flocculated bentonite matrix. • The flocculated bentonite matrix entraps water in its micropores. • BHET hydrogel constrained drainage path. • The hydroxyl groups of BHET retain a high amount of water. • The carbonyl and hydroxyl groups adsorb Pb2+. Polyethene terephthalate (PET) waste poses major environmental harm which can be minimized by reusing it in clay soil stabilization. In general, various polymers are known to reduce hydraulic conductivity and increase the shear strength of clays. However, the application of the effect of a chemically depolymerized form of PET, i.e., Bis (2-Hydroxyethyl) terephthalate (BHET) has not been performed as an additive in Compacted Clay Liners (CCLs) for landfills. This research focuses on the effect of the air curing period (1 and 28 days) on the hydromechanical behavior of BHET-treated SBM (0, 1, 2, 3, and 4 % by dry weight). Results from One Dimensional Consolidation tests showed that an increase in BHET content reduced both compressibility and hydraulic conductivity of SBM due to pore clogging mechanism of swollen BHET hydrogel, however, hydraulic conductivity reduced over 28 days of curing due to loss in re-swelling availability of the hydrogel, thereby allowing less tortuous paths to flow. Results from Consolidated-Drained Direct Shear tests showed that for 1 and 28-days curing, BHET treatment to SBM increased the cohesion (c') due to strong polymer interparticle bridging, however, polymer coating over the sand grains causes a reduction in its surface roughness to decrease the frictional angle (ϕ'). SEM (Scanning Electron Microscopy) and EDX (Energy-dispersive X-ray spectroscopy) analysis on BHET-treated specimens support the flocculation of bentonite, polymer bridging of sand and clay-sand polymer links. A significant Pb2+ removal capacity was also observed with BHET-treated SBM from the batch tests. FTIR (Fourier Transform Infrared Spectroscopy) analysis on batch sorption specimens confirms the role of the carbonyl groups (C = O) and hydroxyl groups (OH) present in the BHET structure indicating the possibility to adsorb Pb2+. The findings of the study suggested that a mechanism of interaction exists between sand-bentonite and BHET polymer and it can be adopted in CCLs design. [ABSTRACT FROM AUTHOR]

Green rusts (GR) are important drivers for trace metal and nutrient cycling in suboxic environments. We investigated whether green rusts would incorporate aluminum (Al) or other elements from naturally-formed clay minerals containing easily-weatherable clay minerals (e.g. mica, interlayered clays). We isolated the clay minerals from a Matapeake silt loam soil by removal of silt and sand, organic matter, and reducible oxides to study mechanisms of interaction between Fe(II) and soil-sourced clay minerals. We conducted batch Fe(II) sorption experiments at multiple near-neutral pHs (6.5–7.5) and reaction times (2 h–365 days). Mineral transformations were characterized by selective extractions, X-ray diffraction (XRD), and Fe X-ray absorption spectroscopy (XAS) analyzed by shell-fitting and linear combination fitting (LCF) with natural and synthetic standards. Clay mineral fraction contained a mixture of quartz, kaolinite, interlayered vermiculite, mica, and chlorite with significant structural Fe (2.6% wt). Uptake of Fe(II) increased with pH and kinetics were rapid until 5 days, followed by slow continuous Fe(II) uptake. Citrate-bicarbonate desorption kinetics from Fe(II) sorbed clay released more Al and silicon (Si) compared with unreacted soil clay fraction whereas magnesium (Mg) and potassium (K) were unaffected. Citrate-bicarbonate extracted Fe contained more Fe(II) than an ideal GR with an Fe(II)/Fe(III) molar ratio of 5.50. Analysis of the Fe EXAFS by both LCF and shell fitting was best modeled as a combination of Fe(III)-clay reduction to Fe(II) and precipitation of GR and Fe(II)-Al LDH. After 7 days of Fe(II) sorption, LCF identified 55.2% total Fe in clay, 33.4% GR(Cl) and 11.4% Fe(II)-Al LDH. These results provide novel evidence of Fe(II)-Al LDHs precipitating on naturally-formed soil clay minerals as a minor phase to GR. The geochemical implications are that GRs formed in soils and sediments should be considered to have Al and Si as well as Mg substitutions affecting their structure and reactivity. [ABSTRACT FROM AUTHOR]

Stable isotope ratios of hydrogen (δ2H values) in local meteoric water correlate with those of nonexchangeable H (δ2H n) in bulk soil and organic matter, allowing for probabilistic spatial assignments to soil samples. We hypothesized that there is a similar correlation between the δ2H values of local meteoric water and the δ2H n value of soil clay fractions. The H pool of topsoil clay fractions is usually dominated by pedogenic clay minerals, which contain structural hydroxyl-H, preserving the δ2H values of ambient water at the time mineral formation. We applied a steam equilibration method with water vapors of known δ2H values to determine δ2H n values in soil clay fractions by eliminating the influence of easily exchangeable H. We collected topsoil samples from 24 locations on five continents with a wide variation in δ2H values of meteoric water. To calculate δ2H n values via steam equilibration, the equilibrium fractionation factor between exchangeable H in the clay fractions and equilibration waters (α ex–w) is needed, which is, however, unknown. We therefore assessed the effect of α ex-w values from 1 (no fractionation) to α ex-w = 1.08, which has been used in steam equilibration approaches of organic matter and bulk soil, on the δ2H n values of soil clay fractions. The δ2H n values of the clay fractions ranged from –167 ± SD1‰ for a northern Siberian sample to –44 ± 4‰ in western Kenya for α ex-w = 1 and from −191 ± 5 to –81 ± 5‰ for α ex-w = 1.08. The δ2H values of local meteoric water correlated significantly with the δ2H n values of the clay fractions (r = 0.85 for α ex-w = 1 and 0.65 for α ex-w = 1.08, p < 0.001). A multiple regression model including hillslope as a possible measure of the accumulation of clay minerals with a slightly different δ2H n value from nearby locations by eolian or aqueous transport in addition to the mean seasonal δ2H values of local meteoric water explained up to 89% of the observed variation in δ2H values of the clay fractions. Our results demonstrate that the δ2H n values of soil clay fractions are driven by the δ2H values of local precipitation on a global scale, irrespective of the used α ex–w value and influenced by the mineral type. Overcoming previous methodological limitations opens up opportunities for probabilistic spatial assignments of unknown organic matter-poor topsoil samples, applications to paleosoil problems or to experimentally track clay mineral neoformation in soils by tracer experiments. [ABSTRACT FROM AUTHOR]

• Soil texture sample taken from field area was silt clay soil. • Parameters determine the draft force of ard plow in silt clay soil were identified. • Parameters used to develop draft force of ard plow were reduced using dimensional analysis. • Parameters using to predict draft force was fitted with measured draft force. • Mathematical model was developed and it can help to reduce draft force and can be input for designing ard plow. Due to Ethiopia's rising population, the prediction of a draft force has several crucial in improving tillage performance in smallholder farmland. It helps in proper usage of animal draught; minimizes operator tragedy and full input data for the ard plow designer. This study aimed to develop an effective mathematical model by selecting appropriate soil properties, tool geometries, and tillage operating conditions for estimating the draft force of the ard plow. A mathematical equation was established using dimensional analysis related to PI-Buckingham-pi theorem. The model was verified and validated using the IBM SPSS statistical software. The correlation between draft force between the measured and predicted value of R2 was 0.877. The developed model was effective in predicting the draft force success for ard plow as much as 87.70%. No significant difference existed between the measured and predicted values at a 0.05 significance level. The scoring standard of the measured draft and the anticipated draft force is normally distributed with a level of confidence of 99%. Investigation consequence showed a developed mathematical formula for estimating the draft force of ard plow in silt clay soil is effective. [ABSTRACT FROM AUTHOR]

• Soil thrust allows remotely operated vehicles to move forward. • Three failure modes are geometrically possible at the soil-track interface. • Upper-bound solutions for soil thrust are mathematically derived. • Resultant soil thrust is determined as the least upper-bound solution. • Proposed solution efficiently and accurately predicts the soil thrust. This study proposes a quick and reliable method for estimating the soil thrust in clay ground for a tracked vehicle based on limit analysis in three-dimensional conditions. With respect to the shape and location of failure surfaces in clayey ground, block, triangular wedge, and trapezoidal wedge failure modes were considered. Between the upper-bound solutions from the different failure modes, the least upper-bound solution was proposed as the soil thrust. To verify the proposed solution, it was compared to the model test and numerical simulations for a track system over model clay ground. The proposed upper-bound solution is expected to produce a reliable soil thrust quickly in real time, especially for submerged heavy-weight remotely operated vehicles (ROVs). [ABSTRACT FROM AUTHOR]

Flexible conductive materials are widely used in structural health monitoring; it is also known in geotechnical engineering. In this preliminary study, a strain-self-sensing smart geogrid rib was proposed to monitor the induced strain by wetting-drying cycles of the expansive soil. After the calibration, a physical modeling test was conducted with the smart geogrid rib reinforced in expansive soils under three wetting-drying cycles. Results demonstrated: that the smart geogrid rib was capable of self-sensing its strain; the strain self-sensed by the smart geogrid rib was in good agreement with that measured by FBG strain sensors before cracks were generated; it could capture the crack propagation of expansive soils during wetting-drying cycles by the discrepancy compared to FBG sensors. Further study will be continued for the mechanism of the geogrid instead of the geogrid rib and the application to real-time monitoring of the performance of the geosynthetic expansive soil slopes. • A geogrid rib was fabricated with flexible conductive materials to make the strain-self-sensing possible. • A physical modeling test was conducted to demonstrate the application of the smart geogrid rib in the expansive soil. • The geogrid rib could sense the crack propagation of expansive soils, and strains measured agreed with strain sensors. [ABSTRACT FROM AUTHOR]

• A unified gross traction algorithm is proposed for braked, towed, and powered wheels on clay. • The model is developed using the Database Records for Off-road Vehicle Environments. • The algorithm employs the ratio of average contact pressure to cone index. • The new equation can be implemented in off-road mobility models. A characteristic curve is presented for predicting gross traction of a wheel over a range of powered, towed, and braked modes on clay soils for slip ranging from positive 100% powered slip to negative 100% skid slip. The characteristic curve is a unified approach that relates the ratio of the contact pressure of the wheel to soil strength and predicts the gross traction coefficient over a continuous range of slip. The unified equation is defined by five inflection points: maximum/minimum traction, traction at zero slip, max change in traction with slip, and a shape factor coefficient. The inflection points aim to simplify the calibration of gross traction, slip, soil strength, and contact pressure by using functions adaptable to machine learning. The unified equation is comparable to historic traction equations but is unique in its ability to predict asymmetric braking and powered gross traction. The unified equation is supported and substantiated via error analysis by utilizing the Database Records for Off-road Vehicle Environments (DROVE) – a database constructed around the archived laboratory and field tests for wheels and tracks operating on different soils. The accuracy of the proposed model is assessed and compared to other conventional equations such as the Brixius equation and Maclaurin's extension of the Pacejka equation for off-road traction. [ABSTRACT FROM AUTHOR]

The paper investigates the feasibility of using fine-grained soil as backfill material of geosynthetic-reinforced walls and slopes, through a laboratory study on pullout behavior of geogrids in granular layers. A series of pullout tests was carried out on an HDPE uniaxial geogrid in thin sand and gravel layers that were embedded in clay specimens. Aside from different soil arrangements, the influences of moisture content and overburden pressure on the geogrid pullout behavior is assessed and discussed. The tests were carried out at four different gravimetric water contents (GWC) on the dry and wet sides of the clay optimum moisture content (OMC), and overburden pressure values within the range σ v = 25–100 kPa. Particle Image Velocimetry (PIV) was used to capture digital images during the tests, which were processed to help with the interpretation and improved understanding of the soil-geogrid interactions at different GWC values. Results show that embedding geogrid reinforcement in layers of sand or gravel can significantly increase the pullout resistance in an otherwise moist clay backfill, and this improved pullout efficiency is greater at higher overburden pressures. The improvement in pullout capacity was observed in clay specimens compacted at both the dry and wet sides of the OMC. • Pullout performance of a uniaxial geogrid in different soils was studied. • Soils included clay, sand, gravel and clay specimens with single layers of reinforced sand or gravel. • The PIV technique was used to observe and interpret soil-geogrid interaction during the pullout process. • Factors examined included moisture content, particle size and thickness of granular layer, and overburden pressure. [ABSTRACT FROM AUTHOR]

Penicillium oxalicum SL2 (SL2) is a previously screened Pb-tolerant fungus that can promote crops growth. The relationship between SL2 colonization and Pb immobilization was studied to provide a theoretical basis for microbial remediation of Pb-contaminated paddy soil. In this study, green fluorescent protein (GFP) labeled SL2 was inoculated into different Pb-contaminated paddy soils (S1-S6). The Pb extracted from the soil by HNO 3 , EDTA and CaCl 2 were used to characterize the available Pb. The results showed that the colonization of SL2 was divided into lag phase (0-7 days), growth phase (7-30 days), and mortality phase (30-90 days). SL2 colonized well in sandy soils rich in clay and total phosphorus with initial pH of 4.5-7.0. In addition, SL2 increased soil pH and decreased soil Eh, which was beneficial to immobilize Pb. In different soils, the highest percentages of CaCl 2 -Pb, EDTA-Pb, and HNO 3 -Pb immobilized by SL2 were 34.34%-40.53%, 17.05%-20.11%, and 7.39%-15.62%, respectively. Pearson correlation analysis showed that the percentages of CaCl 2 -Pb and EDTA-Pb immobilized by SL2 were significantly positively correlated with the number of SL2 during the growth phase. SL2 mainly immobilized Pb in the growth phase and a higher peak number of SL2 was beneficial to the immobilization of Pb. [Display omitted] [ABSTRACT FROM AUTHOR]

Sodic soil formation, following irrigation with saline-sodic water has become a major concern due to its negative impact on soil structure, crop growth and yield. However, specifically in orchards, little knowledge exists regarding the reclamation of sodic soils. Our objective was to examine the effects of different amendments on soil reclamation and crop performance of olive grove. The study was conducted in a 14 years old olive grove, grown in a clayey soil, in which irrigation started in 2008 using saline-sodic water resulting in sodium adsorption ratio (SAR) ranging from 22 to 40 (mmol c L−1)0.5. Six treatments were studied: control (no amendments applied), CaCl 2 , MgCl 2 and H 2 SO 4 that were added to the irrigation water, and gypsiferous material (GM) that was added to the soil surface prior to the rainy season and either left spread or tilled into the upper soil layer. Soil samples were analyzed for selected saturated extract properties and for aggregate stability. Additionally, plant parameters including yield, trunk expansion, fruit oil content, and tree nutritional status were measured. The results showed that the lowest SARs were observed in the GM and GM till treatments at 0–30 cm [5.0 and 3.3 (mmol c L−1)0.5, respectively], while CaCl 2 and MgCl 2 treatments had the lowest SARs at 30–90 cm [16.2 and 17.1 (mmol c L−1)0.5, respectively]. GM and CaCl 2 application raised the electrical conductivity (EC) levels to 6.9 and 7.6 dS m−1 respectively. GM addition resulted in the most stable aggregates which was associated with a significant improvement in average tree productivity of 33 kg/tree. Conversely, MgCl 2 had the lowest average yield, of 21.3 kg/tree, which was attributed to the high concentration of Mg that led to some nutrient imbalances. In conclusion, the current study showed the efficacy of different amendments based on Ca for remediating sodic soil in drip-irrigated orchards. • Soils irrigated with sodic water require reclamation. • Gypsiferous material addition yielded stable aggregates and improved crop productivity. • Adding CaCl 2 and MgCl 2 effectively decreased SAR to a depth of 90 cm. • Amending with MgCl 2 caused nutrient imbalances. • Addition of sulferic acid was ineffective in sodic soil remediation. [ABSTRACT FROM AUTHOR]

Soil cracking can significantly alter the water and nutrient migration pathways in the soil, influencing plant growth and development. While biochar usage has effectively addressed soil cracking, the feasibility of using less energy-intensive hydrochars in desiccating soils remains unexplored. This study investigates the impact of wood and peanut shell hydrochars on the desiccation cracking characteristics of clayey soil. A series of controlled environmental laboratory incubations with regular imaging was conducted to determine crack development's dynamic in unamended and hydrochar-amended soils. The results reveal that the addition of wood hydrochar at 2% and 4% dosage reduced the crack intensity factor (CIF) by 22% and 43%, respectively, compared to the unamended control soil. Similarly, the inclusion of peanut shell hydrochar at 2% and 4% lowered the CIF by 22% and 51%, respectively. The presence of hydrophilic groups on the surface of hydrochars, such as O–H, CH, and C–O–C, enhanced the water retention capacity, as confirmed by Fourier-transform infrared analysis. The CIF decrease is attributed to mitigated water evaporation rates, enabled by enhanced water retention within the hydrochar pore spaces. These findings are supported by scanning electron microscopy analyses of the hydrochar morphology. Despite CIF reduction with hydrochar incorporation, the crack length density (CLD) increased across all hydrochar-amended series. In contrast to unamended soil which exhibited pronounced widening of large cracks and extensive inter-pore voids, the incorporation of hydrochar resulted in higher CLD due to the formation of finer interconnecting crack meshes. Consequently, the unamended control soil suffered greater water loss due to heightened evaporation rates. This study sheds new light on the potential of hydrochars in addressing desiccation-induced soil cracking and its implications for water conservation. [Display omitted] • The addition of wood and peanut shell hydrochars reduced crack intensity factor by 43 and 51% compared to the unamended soil. • The crack length density increased in the hydrochar-amended soil. • The addition of hydrochar contributed to a reduction in water evaporation rate. • The presence of hydrophilic groups on the surface of hydrochars enhanced the water retention capacity. [ABSTRACT FROM AUTHOR]

• Fiber-optic sensing technique is innovatively applied in the field of hydrology and geotechnical engineering. • Fiber Bragg grating (FBG) is utilized to continuously monitor soil water potential. • FBG-suction method can measure a wide range of total suction accurately and efficiently. • The geophysical method holds significant potential for characterizing dynamic surface processes. Accurate measurement of soil water potential or suction is crucial for hydrology and geotechnical engineering. Inspired by recent advances in fiber-optic sensing techniques, we develop an innovative geophysical method for measuring the soil suction by using fiber Bragg grating (FBG), named FBG-suction method. In this study, working principles and theoretical background associated with the FBG-suction method are discussed. For verification purposes, a series of laboratory-scale tests including calibration, suction measurement, and evaporation monitoring are performed on two clayey soils of low to high plasticity under different degrees of saturation. The calibration and measurement results demonstrate the efficacy and accuracy of the developed method for measuring a wide range of soil suction. The curves of soil saturation with suction obtained by WP4C and FBG-suction method are comparable and reflect the difference in the water retention capacity of the tested soils. Additionally, the evaporation monitoring results show that the FBG-suction method can measure the low suction during the drying process and accurately obtain the high suction above the measuring range of the PST-55 psychrometer. The findings affirm the scientific viability of the fiber-optic sensing technique for acquiring the spatial distribution of water potential or suction in unsaturated soils and provide a novel perspective for future investigations into the spatiotemporal evolution characteristics of in-situ unsaturated soil under climate change. As interdisciplinary collaborations continue to advance, it becomes increasingly apparent that methods based on fiber-optic sensing have the potential to revolutionize traditional approaches to characterizing dynamic subsurface processes. [ABSTRACT FROM AUTHOR]

• A conceptual model is proposed to categorize soil pore water types. • Quantitative analysis on pore water redistribution during soil dry-wet processes. • The SWCC can be predicted using the NMR cumulative pore water distribution curve. The pore water distribution (PWD) of soil provides key information about soil shear strength, hydraulic conductivity, and water-retention ability. The PWD characteristics of the soil depend on the specimen preparation conditions (i.e., the variations in initial water content or compaction degree) and drying-wetting processes, which were investigated by using the nuclear magnetic resonance (NMR) technique. The NMR T 2 spectrum is mathematically transformed into the PWD curve to more accurately quantify the variations in pore water content stored with pores of different radii. The pore water in silty clay can be categorized into strongly bound water, intra-aggregate pore water, and inter-aggregate pore water, which are identified by the pore radius of <0.05 μm, 0.05-1.0 μm and >1.0 μm, respectively. The effects of compaction degree and initial water content on the PWD of the soil exhibit distinctions. For unsaturated compacted specimens, the PWDs remain unaffected by changes in compaction degree, while an increase in initial water content promotes the formation of clay aggregates, thereby increasing the maximum water-holding pore radius and the intra-aggregate pore water content. For saturated compacted specimens, the inter-aggregate and intra-aggregate pore water content increases with a decrease in the compaction degree, while the changes in the PWD shape from unimodal to bimodal with an increase in the initial water content. During the soil drying process, inter-aggregate pore water is rapidly drained, the intra-aggregate dominant pore water content increases first and then decreases, and the strongly bound water content remains constant. The relationship between the cumulative pore water distribution curve and the soil-water characteristic curve (SWCC) can be established through the Young-Laplace theory. The SWCC can be well predicted by using the envelope of the cumulative pore water distribution curves during soil drying. [ABSTRACT FROM AUTHOR]

Soil microbial communities play a crucial role in the accumulation and stabilization of soil organic carbon (SOC) through complex processes involving plant residue transformation and mineral interactions. These processes are influenced by plant inputs and modulated by soil properties that are mostly determined by the parent material. However, our understanding is limited regarding the manner in which vegetation and parent material affect microbial community structure, necromass accumulation, and their subsequent impact on SOC storage. To bridge this knowledge gap, we conducted an in-depth investigation focusing on the top-down influence of vegetation type and the bottom-up effect of parent material on microbial-mediated carbon transformation across soil profiles in a tropical region. Our study encompassed 42 sites on three parent materials (basalt, granite, and marine sediments) and four vegetation types (rubber, banana, areca plantations and uncultivated grassland). Soil samples were collected at 0–20, 20–40, 40–80, and 80–100 cm depth. Microbial community structure and necromass were quantified using microbial biomarkers of phospholipid fatty acids and amino sugars, respectively. In rubber plantations, we observed a trend toward higher microbial biomass that, though not significant when compared to other vegetation types, transformed to a significantly higher accumulation of microbial necromass. This increase in microbial necromass was linked to the accumulation of SOC facilitated by the presence of clay size minerals in clayey soils developed from basalt. In particular, basaltic soils were dominated by bacteria, which facilitated the accumulation of bacterial necromass that significantly bolstered its contribution to SOC. In contrast, in sandier soils developed from granite and marine sediments, fungal communities and necromass dominated due to the propensity of fungi for coarser soil environments. Overall, the main impact of vegetation on microbial communities and necromass accumulation was primarily demonstrated for the topsoil. Differences in soil texture arising from different parent materials exert significant effects on the fungal-to bacterial-biomass and necromass ratios, consequently influencing the contribution of fungal and bacterial necromass carbon to SOC across soil profiles. Our study underscores the pivotal role of parent material in governing tropical profile-scale soil carbon storage by shaping the structure of microbial communities and influencing the retention of microbial necromass. • Soils in rubber plantations showed higher microbial necromass content than other vegetation types. • Parent material had a greater influence on microbial necromass retention than vegetation. • Clayey basaltic soils retain more microbial necromass and SOC, dominated by G+ bacteria. • Bacteria dominate basaltic soils, while fungi prevail in sandy granite and marine sediment soils. [ABSTRACT FROM AUTHOR]

• The failure mechanism of the soil between the digging holes was analyzed with the experimental work and related numerical simulations. • The optimum hole spacing was determined with the limit state method during the rectification process of underexcavation. Furthermore, some specific hole spacing values were suggested considering the stochastic characters of the soil. • The method was testified using the actual engineering projects with the reliability and accuracy. The underexcavation technique is one of the most commonly used ones for the rectification of leaning buildings. It usually involves hole digging, and soil removing in the base. The potential failure of the soil between the digging holes determines the hole spacing, which is of critical importance in the safety and efficiency of the entire rectification procedure. The determination of the hole spacing is primarily related to the soil parameters, the upper load induced by the structure, and the holes diameter. In context with this problem, an experimental study, and related computational simulations were conducted with three different hole spacing values. The failure mode of the soil between the holes, and the settlement were studied. It was found that for smaller hole spacing, the failure and the settlement of the soil was more pronounced. Thus, an optimal hole spacing was sought, which was related to the starting point of the leaning building straightening back. In this context, the finite element limit method was employed to determine the optimal hole spacing, with the soil ultimate strain treated as the failure criterion. Further, a parametric study on typical clay and silty soils was undertaken, and the optimal hole spacing values for different upper loads were determined for three typical cases of soil parameters. Finally, three actual rectification projects were considered to assess the reliability of the developed procedure. Hopefully, this method can be a facilitating tool for apriori studies, and initial planning of rectification related engineering projects. [ABSTRACT FROM AUTHOR]

Determination of fruit core temperature is crucial for fruit post-harvest management. However, there is still a lack of precise and real-time intelligent monitoring techniques of fruit core temperature for pre-cooling process and long-term storage. This study aims to establish a physical twin model capable of simulating kiwifruit core temperature. Firstly, we investigated the relationship between pre-cooling efficiency and six fruit characteristics of two kiwifruit cultivars. The results showed that fruit weight and fruit volume were the two main factors affecting the pre-cooling efficiency (R2 = 0.68 in average), and physiological factors such as firmness and soluble solid content had less important impacts. Secondly, we developed a physical twin model comprising special clay and special soil, which could precisely simulate the kiwifruit core temperature (R2 = ∼0.999). Finally, the model was successfully used for intelligent determination of kiwifruit core temperature in pre-cooling through real-time detection algorithm and wireless transmission. Taken together, the physical twin model for the determination of kiwifruit core temperature developed in this study is a useful tool for temperature monitoring during postharvest pre-cooling. • The pre-cooling performance of kiwifruit has been investigated. • A new recipe accurately simulates the core temperature in kiwifruit. • Wireless, real-time monitoring technology detects kiwifruit core temperature. [ABSTRACT FROM AUTHOR]

• Long-term expansion rates of 46 Urban Gullies in Kinshasa and Bukavu are quantified. • Gully widening is responsible for most of the gully expansion. • Expansion rates in sandy soils are mainly controlled by land cover and road density. • Expansion rates in clayey soils appear influenced by landslide dynamics. Urban gullies (UGs) are a growing concern in many tropical cities of the Global South. Addressing this new geo-hydrological hazard requires good insights into the rates and controlling factors of this process. Therefore, we investigate the expansion rates of a representative sample of UGs in Kinshasa (n = 17) and Bukavu (n = 29), two contrasting cities in D.R. Congo. We reconstruct long-term (10–17 years) expansion rates, making a distinction between headcut retreat and sidewall widening, and analyse the environmental factors potentially explaining these rates. Total expansion rates varying between 12.6 and 863 m2y-1. Most of this expansion happens through sidewall widening. In Kinshasa, which is mainly characterized by sandy soils, contrasts in expansion rates are mainly correlated to the characteristics of the upslope drainage area of the gullies. Especially the road density and a hypothetical runoff index (combining drainage area, land use and soil characteristics) explain a significant part of the observed variation. In Bukavu, such trends are less apparent. This is likely because the clayey nature of the soils provides more resistance against gullying, resulting in overall smaller and less actives UGs. Furthermore, the already low infiltration rates of these soils probably make the relative impact of urbanization on runoff production smaller. Our results also indicate that UGs located in recent landslides have higher gully expansion rates. The mechanisms behind remain poorly understood. Overall, our work opens promising perspectives to model and predict gully expansion rates in urban settings but may also guide efforts aiming to stabilize UGs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Soil silt/clay and nutrients increased with increasing distance from the shelterbelt. • Downslope deposition lead to an increase in plow pan thickness and a decrease in bulk density. • Erosion rate was primarily affected by shelterbelt distance, followed by elevation. • Sites closer to shelterbelt warrant particular attention due to coarse-texture materials. Soil erosion is the most severe form of land degradation globally. Farmland shelterbelts are important for reducing erosion, especially erosion caused by the co-occurrence of water and wind. However, few studies have focused on how the distance from the shelterbelt associated with farmland topography affects the redistribution of soil quality indicators. The aims of this study is to reveal the relative importance of these two factors to soil quality under typical wind and water erosion conditions concurrent with the Songnen Plain, China. Topsoils (0–10 cm) were sampled at seven distances from the shelterbelt with three replicates, where topography heterogeneity was also considered. We found that the silt/clay content and soil nutrients at sites farther from the shelterbelt were significantly greater than those at sites closer to the shelterbelt (P < 0.05). Similarly, deposition was dominant at sites farther from the shelterbelt and downslope positions, while erosion was dominant at sites closer to the shelterbelt and upslope positions. Moreover, we discovered that the relative influence of distance from the shelterbelt and farmland elevation varied with individual soil quality indicators. Soil nutrients increased through the deposition of more fine-textured soil (silt/clay) positions farther from the shelterbelt. The downslope region responds to soil deposition by enhancing the plough pan thickness and lowering the bulk density and pH. Overall, distance from the shelterbelt and farmland elevation had interactive effects on soil quality, and erosion was primarily affected by distance from the shelterbelt (63.4 %), followed by elevation (22.7 %). Furthermore, the sites closer to the shelterbelt (i.e., 20 to 420 m) warrant particular attention due to the deposition of coarse-texture materials here. This work is crucial for an improved understanding of the synergistic effects of long-term water and wind co-occurrence on soil quality evolution. [ABSTRACT FROM AUTHOR]

• Using in-situ measurements, size fractionation from soil to sediment was investigated for numerous calcareous soils. • The 0.2 mm was suggested as the boundary between high and low erodible fractions of calcareous soils. • Size range of 0.063–0.2 mm was found as the most susceptible fraction to wind erosion. • Soil fraction of 0.063–0.1 mm intensified calcareous soil potential for suspension-size sediment generation. • Critical values of various soil PSD criteria for wind erosion rate of calcareous soils were suggested. Soil texture and soil surface aggregate size distribution (ASD) are key factors to study soil erodibility by wind and sediment size distribution (SSD) in arid and semi-arid areas. However, less research has studied the effect of soil fractions on soil erodibility and wind-blown sediment size of calcareous soils. In the present study, we focused on the size fractionation and particle size distribution (PSD) of 60 calcareous soil samples collected from 20 semi-arid and arid areas in Fars province, southern Iran. Extensive in-situ wind tunnel experiments were conducted under controlled high wind speed to measure wind erosion rate (WER) and SSD. The results showed that the calcareous soils had different erodibility based on their PSD. Generally, the most erodible soils to the wind force were those with less than 10 % of clay and higher frequency of the 0.1–0.2 mm size class. However, when the soil clay content exceeds 20 %, ASD got dominated with the fraction of 0.4–0.8 mm and WER of the calcareous soils got limited. Besides, size range of 0.063–0.2 mm was suggested as the most wind erodible fraction of the calcareous soils. Furthermore, the mean weight diameter (MWD) of sediment particles averagely reduced 1.3 times as compared to that of the soil samples and WER got inhibited for regions in which the difference of soil and sediment MWD exceeded 0.05 mm. The SSD was significantly controlled by soil PSD and suspension-size sediments < 0.1 mm (SSS) were negatively proportional to soil clay, MWD, geometric mean diameter of soil particles (GMD), dry stable aggregates > 0.25 mm (DSA), and organic carbon as logarithmic equations. Moreover, the presence of the size fractions > 0.2 mm restricted the potential of calcareous soils to generate SSS, which would be quite beneficial for wind erosion combat and dust control of calcareous soils. [ABSTRACT FROM AUTHOR]

In recent years, there has been an increasing interest in investigating the use of non-traditional additives for stabilizing problematic soils. As the demand for eco-friendly alternatives to cement rises, magnesium chloride, a widely used deicer and dust suppressor, has emerged as a potential choice. This study aims to provide a comprehensive understanding of the microstructural changes that occur and affect the macro behavior of treated bentonite (B) and yellow marl (YM). To achieve this, MgCl 2 solution was added to the soils at 3, 6, 9, and 12 percent by dry weight of the soil, and samples were cured for 7, 14, and 28 days at 5° C , 25° C , and 35° C. The mechanical properties of the treated soils were then evaluated using the unconfined compression test, direct shear test, and pressure chamber test (SWCC), while microstructural analysis techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDAX), and Fourier transform infrared spectroscopy (FTIR) were employed to examine the mechanism of MgCl 2 stabilization. The results indicate that adding MgCl 2 and extending the curing period significantly increased both soils' unconfined compressive strength (UCS). However, the UCS value decreased for treated samples cured at temperatures higher than 25°C due to an incomplete cation exchange process and the reduction of apparent cohesion. A part of the gained strength from apparent cohesion and matric suction in the unsaturated samples was lost when the samples reached full saturation during the direct shear test. Changes in the particle size, pore size, and pore void distribution due to the MgCl 2 stabilization affected the SWCCs of the treated soils. Microstructural analyses revealed the formation of magnesium hydration products, such as magnesium silicate hydrate (M-S-H) and magnesium aluminate hydrate (M-A-H), which contributed to the strength increase by increasing grain size, filling the pores, binding fine particles within coarse grains, and forming a flocculated structure through recrystallization of MgCl 2 and the formation of cementitious gel. Additionally, for B, adding MgCl 2 led to soil flocculation through ion exchange, while for YM, the same process occurred due to the greater surface tension of the saline solution encircling the particles. • Microstructural analyses indicated the production of cementitious hydration products M-S-H and M-A-H. • Increasing curing temperature reduced the strength by decreasing the apparent cohesion. • The treatment of the B and YM with MgCl 2 decreased the LL and PI. • Stabilized soil structure changed to a flocculated, interlocked, and denser one. • UCS of both soils improved up to 110 % due to recrystallization and cementation of MgCl 2. [ABSTRACT FROM AUTHOR]

Eutrophication has led to the widespread occurrence of cyanobacterial blooms. Toxic cyanobacterial blooms with high concentrations of microcystins (MCs) have been identified in the Lalla Takerkoust reservoir in Morocco. The objective of this study was to evaluate the efficiency of the Multi-Soil-Layering (MSL) ecotechnology in removing natural cyanobacterial blooms from the lake. Two MSL pilots were used in rectangular glass tanks (60 × 10 × 70 cm). They consisted of permeable layers (PLs) made of pozzolan and a soil mixture layer (SML) containing local soil, ferrous metal, charcoal and sawdust. The main difference between the two systems was the type of local soil used: sandy soil for MSL1 and clayey soil for MSL2. Both MSL pilots effectively reduced cyanobacterial cell concentrations in the treated water to very low levels (0.09 and 0.001 cells/mL). MSL1 showed a gradual improvement in MC removal from 52 % to 99 %, while MSL2 started higher at 90 % but dropped to 54% before reaching 86%. Both MSL systems significantly reduced organic matter levels (97.2 % for MSL1 and 95.8 % for MSL2). Both MSLs were shown to be effective in removing cyanobacteria, MCs, and organic matter with comparable performance. [Display omitted] • Cyanobacterial cell removal by Multi-Soil-Layering (MSL) ranged from 99 % to 100 % • Greater degradation capacity of MC-LR in MSL1 (sandy soil) and MSL2 (clay soil) • MC-YR variant was most persistent in substrate of both MSL systems • qPCR detected degrading bacteria in both MSL systems • MSL1 had significant abundance of mlrA gene copies and degrading bacteria [ABSTRACT FROM AUTHOR]

Current sample preparation strategies for nanomaterials (NMs) analysis in soils by means single particle inductively coupled plasma mass spectrometry have significant constrains in terms of accuracy, sample throughput and applicability (i.e., type of NMs and soils). In this work, strengths and weakness of microwave assisted extraction (MAE) for NMs characterization in soils were systematically investigated. To this end, different extractants were tested (ultrapure water; NaOH, NH 4 OH, sodium citrate and tetrasodium pyrophosphate) and MAE operating conditions were optimized by means of design of experiments. Next, the developed method was applied to different type of metallic(oid) nanoparticles (Se-, Ag-, Pt- and AuNPs) and soils (alkaline, acid, sandy, clayey, SL36, loam ERMCC141; sludge amended ERM483). Results show that Pt- and AuNPs are preserved and quantitatively extracted from soils in 6 min (12 cycles of 30 s each) inside an 800 W oven by using 20 mL of 0.1 M NaOH solution. This methodology is applicable to soils showing a wide range of physicochemical properties except for clay rich samples. If clay soil fraction is significant (>15%), NMs are efficiently retained in the soil thus giving rise to poor recoveries (<10%). The analysis of labile NMs such as Se- and AgNPs is not feasible by means this approach since extraction conditions favors dissolution. Finally, when compared to current extraction methodologies (e.g., ultrasound, cloud point extraction, etc.), MAE affords better or equivalent accuracies and precision as well as higher sample throughput due to treatment speed and the possibility to work with several samples simultaneously. [Display omitted] • Microwave assisted extraction (MAE) is an effective strategy for NMs analysis. • It affords better or equivalent figures of merit and higher sample throughput than current methods. • Pt- and AuNPs are preserved and quantitatively extracted from soils in 6 min by using 0.1 M NaOH. • Clay soil fraction affects negatively NMs extraction. • Labile particles such as Se and AgNPs are deteriorated hampering the analysis. [ABSTRACT FROM AUTHOR]

• A modified permeability testing device is developed to test the permeability of subgrade soil under the overlying stress. • The hydraulic characteristics model, considering the influence of stress and wetting-drying cycles, is established. • A method, repaid obtaining the water migration law of subgrade under stress and wetting-drying cycles, is developed. The wetting–drying cycles and overlying stresses experienced by unsaturated subgrade alter soil pore structure, resulting in variations in its hydraulic characteristics, ultimately affecting subgrade water migration and moisture distribution. However, the combined effects of these two phenomena on key subgrade hydraulic characteristics including the soil–water characteristics and the permeability property remain unclear. This paper aimed to experimentally measure soil–water characteristic curve (SWCC) and saturated permeability of subgrade soil under various overlying stresses and wetting–drying cycles. A customized SWCC measurement system and a modified permeability testing device were developed to conduct the test program on compacted silty clay soil specimens. Subsequently, the influence of overlying stress and wetting–drying cycles on the hydraulic characteristics of the subgrade was analyzed, with a focus on the SWCC and saturation permeability coefficient, and the corresponding fitting model is established. Finally, the water transfer behavior of subgrade considering the effect of wetting–drying cycles and overlying stresses was analyzed using finite element method (FEM). The results indicated that an increased number of wetting–drying cycles and higher overlying stress led to a decrease in the saturated moisture content of subgrade soil, an increase in the air-entry value, and a flatter SWCC. The saturation permeability coefficient increased with the number of wetting–drying cycles, but decreased with increasing overlying stress. Furthermore, a high correlation was observed between the SWCC and permeability coefficient predictive model, considering both the number of wetting–drying cycles and overlying stress. Lastly, when considering the stress state and wetting–drying cycles, significant differences in the evolution of matric suction of the subgrade during rainfall were observed. The overlying stress amplifies the decrease in matric suction of the soil above the subgrade, while wetting–drying cycles reduce this decrease. [ABSTRACT FROM AUTHOR]

Tensile strength is a crucial mechanical property that governs the initiation and propagation of soil tensile cracks. With the global prevalence of warming effects and extreme climatic events, the recurrent freeze-thaw (F-T) cycles intensify the complex evolutions of soil pore structure and tensile strength in regions with widespread seasonal freezing or permafrost active layers. This study investigates the combined influence of F-T cycles and desiccation on the tensile strength of clayey soils. Specimens with varying compaction water contents (14.5%, 16.5%, and 18.5%) and dry densities (1.5 Mg/m3, 1.6 Mg/m3, and 1.7 Mg/m3) were prepared and subjected to cyclic F-T actions. A direct tensile test apparatus was utilized to measure tensile strength (σ t) along the desiccation path. Additionally, the changes in void ratio (e) and suction (s) during F-T cycles were analyzed to understand the mechanism behind the changes in σ t. Experimental results reveal that as the number of F-T cycles (N) increases, water content (w) declines at a decreasing rate and eventually stabilizes. With increasing N , the tensile displacement at failure and σ t show a pattern of initially decreasing and subsequently rising, with the inflection point typically around 1.5%–2.0% lower than the compaction water content (w 0). Under a few F-T cycles, soils compacted at the optimum water content and on the wet side exhibit higher void ratio and lower suction and σ t compared with dry-side compacted soils. However, this trend reverses with further increasing N. In addition, σ t increases as compaction dry density (ρ d0) rises within all water content ranges, primarily attributed to the significant interparticle cohesion controlled by a dense pore structure. The variation of σ t under F-T and associated desiccation is linked with the microstructural evolution characterized by aggregates, interaggregate pores and water-bridges. It is recommended to compact soils both on the dry side of the optimum water content and at the maximum dry density to enhance the freeze-thaw resistance of earth-works in seasonally frozen regions. • Freeze-thaw cycles with desiccation influence compacted soils' tensile strength. • Variations in void ratio and suction during freeze-thaw cycles govern tensile strength. • Soils with higher compaction water content exhibit greater expansion and shrinkage potential. • Dry-side compacted soils resist freeze-thaw risks better. [ABSTRACT FROM AUTHOR]

Tire wear particles (TWPs) are significant contributors to microplastic pollution in the environment, yet there is limited scientific information concerning their impact on soil hydraulic properties. This study aimed to investigate the impact of TWPs at different concentrations (1, 4, 8, and 16% of the air-dried mass of packed soil samples, w/w) on the water retention curves (WRC) of southern California soils with five different textures (clay, clay loam, silt loam, sandy loam, and loamy sand). The concentrations of 8% and 16% were selected to represent extreme pollution scenarios that might occur near highway corridors. High-resolution water retention data, spanning from saturation to oven dryness, were generated using HYPROP™ and WP4C dew point meter instruments. We also developed WRC scaling equations based on the quantity of TWPs. The bulk density of the samples decreased as the TWP concentration in soils increased. The inclusion of very high concentrations of TWPs (8% and 16% w/w) led to a significant reduction in soil moisture content in the intermediate and dry ranges across various soil textures. However, at the same moisture range, adding 1% TWPs had a minimal impact on soil moisture reduction, while the influence of the 4% TWPs concentration treatment was noticeable only in loamy sand and partially in clay loam soils. Additionally, the overall plant available water decreased with increasing TWP concentrations, except for the clay soil. The texture-specific scaling models exhibited promising performance, with RMSE values ranging from 0.0061 to 0.0120 cm3 cm−3. When bulk density was included as an additional input predictor to construct a single scaling model for all textures, the RMSE increased. Nevertheless, it still indicated a good fit ranging from 0.007 to 0.024 cm3 cm−3, highlighting the suitability of simple scaling for identifying WRC in TWPs-polluted soils, particularly for practical purposes. The findings of this study can contribute to a better understanding and quantification of the impact of TWPs on soil hydrology. • HYPROP and WP4C were used for high-resolution measurement of soil water retention from saturation to dryness. • The impact of tire wear particles (concentrations 1–16%) on the water retention curve of 5 soil textures was investigated. • A linear scaling model accurately estimated the soil moisture reduction in the plant available water range due to TWPs. [ABSTRACT FROM AUTHOR]

Soil response analyses require that the soil strata involved be characterized in terms of their dynamic material properties. Two important material properties are the shear modulus and a measure of energy dissipation characteristics, usually expressed as the damping ratio. Both can be obtained from standard laboratory tests, most commonly resonant columns or cyclic triaxial devices which provide strain-dependent values. Alternative experimental procedures are now available to estimate shear moduli at very small strains from piezoelectric transducer tests (bender elements); procedures have also been put forth to obtain the energy dissipation properties from this test. In this paper, we present a modified version of the spectral-ratio method using the wavelet transform to measure the damping ratio at small strains from waveforms acquired from bender element tests. Synthetic bender element signals were first used to test the procedure and validate the approach. Then, we analyzed signals obtained from a large-size oedometer equipped with bender elements on very soft Texcoco Clays (near Mexico City), and the waveforms were propagated along different paths. Our results show that the range of values of D min obtained from bender element tests agrees well with those obtained from resonant column tests performed on very soft clayey soil specimens retrieved from the same area at different depths. • This research is aimed to study the damping ratio on very soft soil Texcoco Clays (near Mexico City) using a large-size oedometer equipped with piezoelectric transducers. • We propose a modified version of the spectral ratio method for assessing the damping ratio at very small strains (elastic behavior). • It is calculated synthetic waveforms which input data are similar to the soil deposits present in the area where the specimens were retrieved. • We compare the data obtained with the modified version of the spectral ratio concerning to resonant column tests. [ABSTRACT FROM AUTHOR]

The paper quantifies the uncertainty of material parameters of the hypoplastic model for clay resulting from the experimenter's choice about what laboratory data are utilised in the calibration process. The results of several 1D compression tests and undrained triaxial shear tests performed on twenty different fine-grained soils are considered in various combinations to yield a scattered set of material parameters for each soil. A hierarchical probabilistic model separating the variations and correlations of parameters within one soil from variations and correlations among different soils is formulated. The posterior distribution of the probabilistic model parameters is obtained by means of the Bayesian inference. The results allow for stochastic simulations on a structural level even when only point estimates of material parameters are available. • Material parameters of hypoplastic model for clay are determined for twenty soils. • Calibration uncertainty of the parameters is quantified for general fine-grained soil. • Covariance within one soil and between different soils is formulated separated. • Results are directly applicable in stochastic analysis with different clayey soils. [ABSTRACT FROM AUTHOR]

The European bioeconomy is steadily driving an industrial, economic, and social growth looking for sustainable biobased feedstocks able to replace fossil-based materials. In this scenario, there is an urgent and increasing need to produce locally industrial crops, with multiple applications and broad suitability to different pedo-climates. Furthermore, the actual EU legislation imposes to produce industrial crops not competing with food ones, and one possibility is to grow them on marginal land. Among others, camelina [ Camelina sativa (L.) Crantz] has been identified as one of the most suitable options for marginal land in Europe, but so far there is a lack of studies conducted in such conditions able to provide reliable production data, on which it will be possible to build plausible business plans. At this scope different field trials have been established in four European countries, i.e., Italy, Greece, Germany, and Poland, in multiple growing seasons from 2018 to 2021, under different types of marginality. In details, in Italy camelina was tested under steep slopes (25% and 15%), in Greece in a soil with low fertility (pH < 5.5) and adverse terrain conditions (steep slope >12%); in Germany in a soil with limitations in rooting, i.e., rooting depth < 30 cm + stoniness > 15%, and in Poland in two sites one with sand > 40%, and the other with clay > 50% of the texture. Camelina was grown with an autumn cycle in Italy and Greece, and with a spring one in Germany and Poland. Camelina production was impacted by the marginal land, seed yield was on average 0.94 Mg DM ha−1, ranging from 0.38 Mg DM ha−1 for camelina sown in spring in Poland in the sandy soil, up to 1.93 Mg DM ha−1 for camelina sown in autumn in Italy on a 15% slope. Camelina completely failed only in one growing season in the clay soil in Poland, in relation to extreme weed pressure, while in all the other situations it was able to produce seed. Seed quality, that was surveyed only in Italy and Poland, was not negatively impacted by marginality, demonstrating its capacity to cope with harsh growing conditions. Growing camelina in southern European marginal land, in autumn sowing, seemed the most conservative and safe strategy to achieve profitable yields. In terms of agronomic management, the most important choices to optimize the crop in marginal land resulted: weed management, N fertilization, and the harvesting phase. • Camelina confirmed to be adapt to European marginal land. • Under marginal land camelina seed yield ranged between 0.38 and 1.93 Mg DM ha-1. • Seed oil content and 1000-seed weight were not negatively impacted by marginality. • Growing camelina in southern European marginal land was the most conservative and safe strategy to achieve profitable yields. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is the largest terrestrial carbon (C) pool and is vulnerable to climate and land-use changes. Promoting the stabilization of SOC will reduce climate change-induced C losses. Mineral-associated organic carbon (MAOC), formed by the association of organic carbon with silt- and clay-sized minerals, is the major stabilized SOC fraction and key to sustaining soil health and mitigating climate change. However, the role of silt and clay in MAOC formation remains unclear in dryland ecosystems where microbes and plants are frequently under water stress. The current paradigm assumes that the main role of silt and clay is to adsorb and aggregate organic compounds. In a semi-arid environment, using a naturally occurring gradient of increasing soil silt and clay content partially due to aeolian dust inputs, we show that silt and clay also enhanced microbial decomposition of plant C inputs and microbial turnover, increasing microbial C inclusion into the MAOC pool. Finer-textured soils had higher soil water availability and higher volume of habitat available to microorganisms. The enhanced microbial processing interacted with changes in plant C inputs to further control the relative contribution of MAOC to SOC. Our results suggest SOC models should include soil textural effects on microbial activities and microbial C production in addition to physical protection of SOC. Our study also suggests that aeolian dust inputs can increase soil silt and clay contents and improve nutrient availability in dryland ecosystems, potentially mitigating the SOC loss under climate change and increasing the resilience of ecosystems to drought. • Silt and clay not only protect microbial carbon from decomposition but also enhance its production in dryland soils. • Silt and clay relieved environmental stress on microbes by increasing soil water content and pore spaces. • Microbial processing interacts with plant inputs to control the contribution of MAOC to SOC. • The effect of litter quality on the accrual of MAOC relative to SOC was negligible in drylands. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stream power and soil clay content were used to model soil erosion rate. • Sediment sorting and transport were controlled by the soil properties. • A linear function was developed to quantify the sediment clay content. • The relative contributions of different transport mechanisms were quantified. Understanding the sediment sorting and transport processes is is crucial for enhancing the understanding of soil erosion mechanisms and improving soil erosion prediction. However, quantitative studies based on the coupling effects of both hydraulic parameters and soil properties are still lacking. In this study, five loessial soils with varying physicochemical properties were collected in the Loess Plateau of China, and simulated rainfall experiments were carried out in a metal box with a slope of 20 degrees under rainfall intensities of 1, 1.5, and 2 mm min−1. Runoff samples were collected to analyze the variation in erosion rates and effective particle size distribution of eroded sediments during the rainfall process. The results showed that the stream power was the optimal parameter to model the erosion rate, and a power function incorporating the clay content and stream power could well predict the erosion rate of different soils. The enrichment ratio indicated the enrichment of fine particles and depletion of coarse particles. And the sediment sorting degree increased with increasing soil clay content. The critical particle size for distinguishing different transport mechanisms varied among soils, with more than 55.46 % of the total sediment transported by suspension/saltation. A linear function and power function including the original soil particle size distribution and stream power were developed to quantify the sediment clay content and the relative contribution of different transport mechanisms. This study could be helpful to improve the soil erosion prediction model and provide basic guidelines for regional soil and water conservation. [ABSTRACT FROM AUTHOR]

• Ca2+ promoted macropores develop toward spheres under Na+ presence. • Under Na+ presence, Mg2+ promoted macropores to develop in one/several directions. • Ca2+ increased macropore size by soil flocculation, but Mg2+ by soil cracking. • Ca2+ affected soil macropore area, but Mg2+ changed macropore number. Cations in soil solutions affect soil structural stability and thus soil quality and health. Ca2+ and Mg2+ could alleviate soil clay dispersion by replacing Na+, which was the main driver. However, Mg2+ could also cause soil disaggregation and weaken aggregate integrity. Currently, most studies on Ca2+ and Mg2+ mainly examine soil hydraulic characteristics and clay particle dispersion, rather than macropore geometry. We analyzed the impact of Ca2+ and Mg2+ on soil macropore morphology by measuring macropore length, aspect ratio, and area indices. An indoor soil column experiment was set up, and irrigation water was prepared with the same electrical conductivity (4 dS m−1) and different cation compositions (Na+-Ca2+ (NC), Na+-Ca2+-Mg2+ (NCM), Na+-Mg2+ (NM) and Na+-only (N) were added), and deionized water as the control (CK). The results indicated that N had the highest soil suspension turbidity among all treatments, with NM being higher than NC. The highest percentage of soil macropore aspect ratio < 2.0 was found in N, and the highest percentage of soil macropore aspect ratio for NCM was found in > 2.0. The macropore anisotropy of NM was closer to 1.0, and anisotropy of NC was closer to 0. The soil macropore morphology of NC developed towards a spherical shape, while the macropores of NM might extend along one or several similar directions. For Na+-Ca2+ dominated soil, Ca2+ mainly affected the macropore area. However, for Na+-Mg2+ dominated soil, Mg2+ primarily influenced the number of macropores. Ca2+ inhibited the negative effects of Na+, but Mg2+ promoted unidirectional extension of macropores, posing a risk of soil cracking. This study provided a better understanding to explore the differences in the effects of different cations on soil pore structure and helped to provide guidance for field water management. [ABSTRACT FROM AUTHOR]

• Patchiness caused significant reduction of SOC and TN stocks. • Reduced vegetation input and increased erosion output accounted for SOC and TN loss. • Grasslands with high patchiness had a great potential for C and N sequestration. Patchiness acts as an indicator of terrestrial ecosystem degradation and can lead to considerable loss of soil organic carbon and total nitrogen. However, quantitative assessments of the effects of patchiness on soil organic carbon and total nitrogen stocks and their associated mechanisms remain limited. This study aimed to explore the influence mechanisms of patchiness on soil organic carbon and total nitrogen stocks and to project the quantitative contribution of the further expansion of patchiness and vegetation recovery. Soil properties, soil organic carbon and total nitrogen stocks were investigated using a combination of field sampling and aerial photography in four grassland types, alpine meadow, alpine steppe, temperate grassland, and desert grassland, at 47 sites in northwestern China. Soil organic carbon and total nitrogen densities in the bare patches were 34–54 % and 23–41 % lower, respectively, compared to the original vegetation. At the plot-scale, current soil organic carbon and total nitrogen stocks ranged from 30.85 to 77.80 T/ha and 3.26 to 10.19 T/ha, respectively, across grassland types; with a 10–27 % and 7–24 % potential loss of soil organic carbon and total nitrogen stocks, respectively, from the further expansion of patchiness but a 10–50 % and 9–37 % potential increase in soil organic carbon and total nitrogen stocks, respectively, from vegetation recovery. Soil organic carbon and total nitrogen stocks were positively correlated with vegetation biomass, soil clay content, and precipitation (p < 0.001), whereas they were negatively correlated with patchiness (p < 0.001). In summary, patchiness reduced soil organic carbon and total nitrogen stocks by decreasing vegetation inputs and increasing erosion outputs, while vegetation recovery showed potential for increasing carbon and nitrogen stocks. Our results highlight that maintaining intact vegetation cover is critical for preserving terrestrial ecosystem carbon and nitrogen storage. [ABSTRACT FROM AUTHOR]

• Clay content and subfreezing temperature coupling affect soil FT deformation. • The clay aggregate evolution during FT accounts for the complex deformation. • Full-range evolution of soil structure is characterized via NMR and X-CT. • Quantitatively analyze contribution of micro/meso structure change to deformation. Climate change brought about significant freeze–thaw (FT) deformation of clayey soils distributed in cold regions, which resulted from soil structure evolution including pore size distribution change and crack development. However, the formation of clay aggregate that dominates the soil deformation behavior during FT remains unclear. This study investigated the effects of clay contents (5 %, 10 %, 15 %, and 20 %) and subfreezing temperatures (−5 °C, −10 °C, and −15 °C) on the soil FT deformation properties by isotropic isothermal FT tests. Meanwhile, the soil structure evolution was characterized via Nuclear Magnetic Resonance and X-ray Computed Tomography. The results indicated that the frost heave ratio (η) and thaw settlement coefficient (δ) non-linearly varied with clay content and subfreezing temperature. Specifically, the minimum η and δ were observed in the specimen with 10 % clay content, and the maximum η and δ were identified at −10 °C. This phenomenon can be attributed to the clay aggregate forming bimodal or unimodal pore size distribution (PSD) with different initial clay contents. The freezing characteristics of inter- and intra-aggregate pore water were determined by the solid-water interaction. Moreover, the FT action altered the structure of clayey soil by the change in PSD and the generation of cracks. The contribution of pore size change and crack development to the total volume change before and after FT was quantitatively analyzed. It demonstrated that pore size change was more important for the total volume change in specimens with lower clay content and higher subfreezing temperature, whereas crack development mainly contributed to the total volume change in the rest of the specimens. This study provides a deep insight into the deformation characteristics of clayey soils under different climate conditions in cold regions. [ABSTRACT FROM AUTHOR]

The present work describes the process of degradation of a polyelectrolytic complex (PEC) based on sodium alginate (ALG) and chitosan (CHI), buried for different time intervals, in a clayey soil (ultisol) collected from the municipality of Campos dos Goytacazes, in the northern region of the state of Rio de Janeiro, Brazil. The influence of PEC on soil moisture was also investigated. The results showed that soil moisture increased with the presence of PEC after 7 days of testing, and remained high until the end of the study. FTIR and Raman spectra showed that the breaking of the glycosidic bond (C-O-C) was responsible for the PEC degradation. Thermogravimetry results revealed that alginate was possibly degraded faster than chitosan. Microscopic analysis of the PEC revealed a fragile and fragmented surface of the samples that were buried, in comparison with those not buried. The microbiological assays of the soil confirmed the biodegradation of the polysaccharides. Chemical analysis of soil indicated that PEC did not significantly influence soil fertility. Therefore, we conclude that the PEC (ALG: CHI), formed only by electrostatic interaction, buried in clayey soil, even being biodegraded, can be a promising soil conditioner for agricultural applications. • Degradation process of alginate-chitosan complex buried in ultisol was investigated. • Samples were completely degraded after 6 weeks of soil burial. • Alginate units was degraded faster than chitosan units. • Microscopy analysis showed a fibrous material after burial for two weeks. • Alginate-chitosan complex can act as soil conditioner for agricultural applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • We analyzed 56 Northern long-term experiments to explore manure effect on SOC. • We developed a statistical model to determine the most effective practices. • SOC saturation occurred with a certain proportion of ley depending on soil texture. • Manure is most effectively used in the crop rotations with low proportion of ley. • Management and circumstances should be considered when targeting SOC sequestration. Soil carbon sequestration has a great potential in climate change mitigation. To maximise carbon stocks in northern agricultural soils, the carbon sequestration determinants of manure application are crucial. We quantified the effect of manure on soil organic carbon (SOC) depending on the application rate, proportion of leys relative to annuals in crop rotation, and soil texture. We compared the steady-state SOC concentration under farm-yard manure application to a control treatment with no manure application based on 56 individual long-term experiments at 27 locations north of 50 degrees north latitude. At a low application rate of manure such as 0.7 Mg C/ha/y, SOC gradually increased with increasing ley proportions. At a moderate manure rate, such as 1.3 Mg C/ha/y, an increase in the ley proportion led to a decreasing growth of, or even a decrease in, SOC. At a low fixed ley proportion in crop rotation such as 20 %, SOC linearly increased with an increasing manure application rate. As the proportion of leys increased, saturation occurred at a certain ley proportion depending on soil texture. When leys occurred on sandy soils more than once out of seven years and the proportion of leys in crop rotation on clay soils was higher than 45 %, increasing the manure application rate led to decreasing SOC accrual. Compared to the absence of manure application, high manure rates even decreased SOC. We conclude that manure application in crop rotation with a low ley proportion maximises SOC accrual in the topsoil. The most effective manure application rate and ley proportion leys in regard to SOC in the northern agricultural landscape can be determined using a statistical model that we developed, depending on the management system and soil texture. [ABSTRACT FROM AUTHOR]

The objective of the present study was to increase the strength and stiffness of silty clay and silty sand subgrades for building economic and sustainable asphalt pavements. Advanced cyclic load tri-axial (ACLT) and California bearing ratio (CBR) tests were performed to obtain the experimental and theoretical resilient modulus (M R) of the soil subgrades, respectively. In addition, the impact of the stabilization of the plasticity and compaction characteristics of the soil subgrades was determined. The insight into the mechanism of the stabilization was obtained by determining the mineralogical and microstructural properties of the stabilized soils through X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) tests, respectively. The combined inclusion of 20% brick kiln dust and 20% pond ash resulted in 186% increase in the CBR, 224% increase in the experimental M R , 96% increase in the theoretical M R , 2.07 times higher pavement service life, 23% savings in cost, and 28% reduction in the CO 2 emissions associated with pavement construction. The enhancement in the CBR and M R of the soils was attributed to the increased inter-particle friction, improved particle size distribution in stabilized clay and sand, and a concurrent reduction in the plasticity of clay. The study highlights the real-world usage of the ACLT test to get the real M R of soil subgrade rather than the over-estimated theoretical M R. For precise estimation of M R from CBR, a correlation between CBR and experimental M R was established. • Pavements built with soil subgrades of low strength and stiffness develops ruts, depressions, and corrugations. • Advanced cyclic load triaxial test is mandatory for the performance evaluation of soil subgrades under dynamic loading. • Experimental approach gives true value of resilient modulus (M R) while theoretical approach overestimates the M R. • Economic and sustainable pavement construction can be achieved with the waste stabilized clay and sand subgrades. • Promotion of use of waste materials for soil subgrade stabilization will help build economic and sustainable pavements. [ABSTRACT FROM AUTHOR]

The application of selenium nanoparticles (Se NPs) in agriculture has garnered significant attention, yet there remains a knowledge gap regarding the correlation between the size of Se NPs and their availability in soil. To address this gap, adsorption experiments, soil column experiments, and pot experiments were conducted to investigate the relationship between the availability in soil of Se NPs and their particle size. The results showed that the adsorption capacities of Se NPs with various sizes (30, 50, 80, 110 nm) to fulvic acid (FA) was decreased with increasing particle sizes and pH. Small sized Se NPs (30 nm) are more stable because they adsorb more organic matter, which significantly decreases aggregation. Moreover, the mobility of Se NPs was decreased by increasing clay content in soil and particle size. These results demonstrated that small-sized Se NPs have higher bioavailability than large-sized Se NPs. The Se content in rhizosphere soil and Brassica chinensis shoot was significantly increased by 319.4% and 220.2% upon exposure to Se NPs (30 nm), higher than that for others (50, 80, 110 nm and 2 µm). The reason is that small-sized Se NPs are more stable in the soil, more easily migrate from the non-rhizosphere to the rhizosphere and interact with crop roots, leading to increased root exudations. These interactions recruit beneficial microorganisms in the rhizosphere. In turn, the improved root exudations and the presence of these microorganisms enhance the bioavailability of Se NPs. Linear regression analysis indicated that the size of soil-applied Se NPs should fall within the range of 11–631 nm, as those outside of this range may not meet the standard for Se-enriched food. Besides, the nutrient accumulation in leaves promoted photosynthesis (81.1%) and increased the yield (113.1%) of Brassica chinensis by small-sized Se NPs (30 nm). Therefore, these information highlights the critical role of Se NPs size in crop Se biofortification for agriculture production. [Display omitted] • Small size selenium nanoparticles (Se NPs) have better stability and migration in soil. • Smaller size Se NPs are more bioavailable in plants and soil. • The size of the Se NPs applied in the soil ranged from 11 to 631 nm, which meets the standard 0.1 for the production of Se-rich vegetables. [ABSTRACT FROM AUTHOR]

Cracking phenomena are prevalent within clayey soils, substantially augmenting the evaporation process and exerting notable influences on soil thermo-hydro-mechanical properties. In this study, a new numerical method is developed to study the evaporation process of cracked soil, coupling moisture migration and heat transfer within both soil and air domains. The interconnection between these domains is established through boundary conditions based on soil-atmosphere interaction. This new model enables precise spatio-temporal tracking of evaporation rates and corresponding water redistribution. It is of significance for assessing the stability of soil slopes with cracks under changing climate. Three sets of numerical tests are performed to investigate the effects of different environmental conditions on the evaporation process: various groundwater tables, atmospheric conditions and crack morphologies. Results revealed that alterations in groundwater levels modify water recharge pathways, leading water content reduces firstly at soils where away from the water table. Atmospheric conditions, represented by D atm , affect the migration of water vapor. When D atm is low, it leads to the accumulation of vapor at the soil-atmosphere interface, consequently decreasing the rate of evaporation. Furthermore, crack morphology plays a significant role in evaporation process at crack surface, notably expediting water loss between cracks, particularly in closer proximities. [ABSTRACT FROM AUTHOR]

In conservation agriculture no-tillage and reduced tillage are used to increase the sustainability of cultivation. There is, however, a paucity of data on the long-term effects of no-tillage and reduced tillage management on the nutrient balances for grain production in a cool and humid climate. This information is relevant for evaluating the effects of primary tillage systems on environmental risks and nutrient input use efficiency of cultivation. In the current study, we examined the long-term effects of primary tillage methods on grain and nitrogen (N) and phosphorus (P) yields, and N and P balance for spring barley (Hordeum vulgare L.) cultivation on a Nordic clay soil (Vertic Endostagtic Cambisol) in 2000−2019. Three types of primary tillage were compared: mouldboard ploughing to 20−25 cm depth, stubble cultivation to 10−15 cm depth (later reduced tillage) and no-tillage. The trial was left without P fertilizer since 2008. Based on the current results, ploughing and reduced tillage were comparable primary tillage methods but no-tillage increased the N and P balances. Barley yield was 12−13% higher for ploughed and reduced tillage treatments than for no-tillage. N yield was 18% and 21% higher and P yield 12% higher with ploughed and reduced tillage compared with no-tillage, respectively. N balance was 43.6, 41.8 and 52.5 kg/ha with ploughing, reduced tillage and no-tillage and P balance was −5.9 kg/ha with ploughing and reduced tillage and −4.5 kg/ha with no-tillage, respectively. • Autumn primary tillage systems were studied for spring barley on a Nordic clay soil. • Grain and nutrient yields were highest using ploughed and reduced tillage. • Wet weather conditions in spring reduced barley yield in a no-tillage environment. • High barley yield had a positive effect on nitrogen and phosphorus balances. • The lack of P fertilizer application for 12 years had no effect on barley yield. [ABSTRACT FROM AUTHOR]

Knowledge of soil organic carbon (OC) components and enzyme activities is essential to maintain soil health and for sustainable land use during long-term vegetation restoration. The effects of vegetation restoration on soil physicochemical properties have been widely documented; however, knowledge of the relationships among soil OC components, enzyme activities, and soil properties in restored ecosystems remains unclear. Here, the soil from four successional stages of restored Robinia pseudoacacia vegetation (10, 20, 30, and 40 years) were sampled in China's Loess Plateau. The soil water content (SWC), bulk density (BD), pH, total nitrogen (TN), soil microbial biomass C (MBC) and N (MBN) contents, OC components (labile and recalcitrant OC), and soil enzyme (hydrolytic and oxidase) activities were measured. We found that restoration time significantly affects soil physicochemical properties, OC components and enzyme activities. Across the restoration time, the SWC decreased from year 10 to year 30, then increased from year 30 to year 40. Soil OC and TN increased with restoration time, while soil clay content decreased with restoration time. Following 40 years of restoration, soil MBC and MBN significantly increased by 214% and 88%, respectively. For OC components, 40 years of restoration significantly increased recalcitrant C component rather than labile C component. Soil hydrolytic enzyme activities significantly increased by 76.9% and 80.3% in 40 years stand compared with that of in 10 years stand, respectively, while soil oxidase enzyme activities significantly decreased with restoration time. Correlation analysis demonstrated that the SOC and MBC content significantly influenced soil recalcitrant C component and hydrolytic enzyme activities, while MBC and clay content significantly influenced soil oxidase enzyme activities. These results provided useful insights on the responses of forest restoration on soil OC components and related OC degrading enzymes and the understanding of soil C sequestration in the restored ecosystems in such areas. [ABSTRACT FROM AUTHOR]

• SOC bioavailability significantly differed among soil particle-size fractions. • SOC bioavailability of fine sand increased by 200 %, whereas clay reduced by 60 % • The porosity of fine sand was 60% of clay. • Abundances of soil elements of clay were 6–30 times higher than fine sand. • Microbial activity, mediated by soil morphology, affected SOC bioavailability. Despite the fact that physical and chemical processes have been widely proposed to explicate the stabilization mechanisms of soil organic carbon (SOC), thebioavailability of SOC linked to soil physical structure, microbial community structure, and functional genes remains poorly understood. This study aims to investigate the SOC division based on bioavailability differences formed by physical isolation, and to clarify the relationships of SOC bioavailability with soil elements, pore characteristics, and microbial activity. Results revealed that soil element abundances such as SOC, TN, and DOC ranked in the same order as the soil porosity as clay > silt ≥ coarse sand > fine sand in both top and sub soil. In contrast to silt and clay, which had reduced SOC bioavailability, fine sand and coarse sand had dramatically enhanced SOC bioavailability compared to the bulk soil. The bacterial and fungal community structure was significantly influenced by particle size, porosity, and soil elements. Copiotrophic bacteria and functional genes were more prevalent in fine sand than clay, which also contained more oligotrophic bacteria. The SOC bioavailability was positively correlated with abundances of functional genes, C degradation genes, and copiotrophic bacteria, but negatively correlated with abundances of soil elements, porosity, oligotrophic bacteria, and microbial biomass (p < 0.05). This indicated that the soil physical structure divided SOC into pools with varying levels of bioavailability, with sand fractions having more bioavailable organic carbon than finer fractions. Copiotrophic Proteobacteria and oligotrophic Acidobacteria, Firmicutes, and Gemmatimonadetes made up the majority of the bacteria linked to SOC mineralization. Additionally, the fungi Mortierellomycota and Mucoromycota, which are mostly involved in SOC mineralization, may have the potential for oligotrophic metabolism. Our results indicated that particle-size fractionation could influence the SOC bioavailability by restricting SOC accessibility and microbial activity, thus having a significant impact on sustaining soil organic carbon reserves in temperate agricultural ecosystems, and provided a new research direction for organic carbon stability. [ABSTRACT FROM AUTHOR]

The Kahramanmaraş Earthquakes that occurred on 6 February 2023 resulted in extensive structural failures, including damages caused by soil liquefaction. This study focused on investigating the excessive settlements observed in buildings along Ataturk Boulevard in the Golbasi district, with a primary emphasis on the toppling failure of the Kayı Apartment. Field exploration, laboratory testing, and bearing capacity analyses were conducted to understand the failure mechanism. Since the foundation soil of Kayı Apartment predominantly consisted of clay, soil liquefaction alone could not explain the observed failure. Instead, the cyclic softening of clayey soil underground shaking was identified as a significant factor contributing to the damage. As one of the rare case histories documenting a failure caused by cyclic softening, the results of the study also shed light on the excessive displacements observed in nearby buildings with fewer stories that managed to withstand the earthquake without experiencing complete bearing capacity failure. [ABSTRACT FROM AUTHOR]

• Immobilization of metals by BC-nZVI process was superior to that of BC or nZVI. • Immobilization of Cd or Pb was inhibited with addition of 2,4-dichlorophenol. • Cd and Pb availability decreased, whereas soil pH and organic matter increased. • Stable metals speices such as CdCO 3 , Cd(OH) 2 , PbCO 3 and Pb(OH) 2 were formed. • Mechanism for the simultaneous immobilization of Cd and Pb in soil was proposed. Risk associated with heavy metals in soil has been received widespread attention. In this study, a porous biochar supported nanoscale zero-valent iron (BC-nZVI) was applied to immobilize cadmium (Cd) and lead (Pb) in clayey soil. Experiment results indicated that the immobilization of Cd or Pb by BC-nZVI process was better than that of BC or nZVI process, and about 80% of heavy metals immobilization was obtained in BC-nZVI process. Addition of BC-nZVI could increase soil pH and organic matter (SOM). Cd or Pb immobilization was inhibited with coexisting organic compound 2,4-dichlorophenol (2,4-DCP), but 2,4-DCP could be removed in a simultaneous manner with Cd or Pb immobilization at low concentration levels. Simultaneous immobilization of Cd and Pb was achieved in BC-nZVI process, and both Cd and Pb availability significantly decreased. Stable Cd species inculding Cd(OH) 2 , CdCO 3 and CdO were formed, whereas stable Pb species such as PbCO 3 , PbO and Pb(OH) 2 were produced with BC-nZVI treatment. Simultaneous immobilization mechanism of Cd and Pb in soil by BC-nZVI was thereby proposed. This study well demonstrates that BC-nZVI has been emerged as a potential technology for the remediation of multiple heavy metals in soil. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, thermomechanical (TM) behavior of laterally loaded energy piles is investigated through analytical and numerical studies. Accordingly, the ultimate lateral load capacity, and the internal moment and horizontal displacement of the pile under service lateral loads, were assessed. Initially, a thermo-elastic-based analytical solution was proposed, and afterwards, a 3D numerical finite element (FE) model was constructed to investigate the effect of different soil parameters, temperature variation and mechanical load conditions on the behavior of energy piles in different soils. Then, the analytical and numerical results were validated against experimental data, and vast analytical/numerical studies were carried out on the TM parameters affecting the behavior of laterally loaded energy piles. Finally, considering the analytical and numerical results, adjusting relationships were introduced to estimate the lateral bearing capacity and the maximum lateral displacement parameters, more precisely. The results showed that in clayey and sandy soils, the ultimate lateral bearing capacity increases by increasing the temperature or by decreasing the external moment. Moreover, heating was found to have an increasing effect on the internal moments and the maximum lateral displacements of the piles embedded in clayey soils, but it had a decreasing effect on the piles embedded in sandy soils. [Display omitted] [ABSTRACT FROM AUTHOR]

To better understand interglacial paleosol development by quantifying the paleosol development processes on the Chinese Loess Plateau (CLP), we need a soil genesis model calibrated for long timescales. Here, we calibrate a process-based soil genesis model, SoilGen2, by confronting simulated and measured soil properties for the Holocene and MIS-13 paleosols formed in the CLP for various parameter settings. The calibration was made sequentially on three major soil process formulations, including decalcification, clay migration and soil organic carbon, which are represented by various process parameters. The order of the tuned parameters was based on sensitivity analyses performed previously on the loess in West European and the CLP. After the calibration of the intrinsic soil process parameters, the effect of uncertainty of dust deposition rate on calibration results was assessed. Our results show that the simulated soil properties are very sensitive to ten reconstructed dust deposition scenarios, reflecting the propagation of uncertainty of dust deposition in model simulations. Our results also show the equal importance of calibrating soil process parameters and defining correct external forcings in the future use of soil models. Our calibrated model allows interglacial soil simulation in the CLP over long timescales. [ABSTRACT FROM AUTHOR]

• A single-reading hydrometer method developed for rapid determination of soil texture. • Bouyoucos' method was not accurate method to determine clay H (H = hydrometer) content. • High correlation was obtained between clay P (P = pipette) and clay H (r = 0.987). • A single-reading of hydrometer at 6 h (P 6) was a good proxy for clay H content. • The P 6 -function excellently predicted clay H content (validation dataset r 2 = 0.985). Standard hydrometer procedure is labor-intensive and time-consuming. We aimed to 1) test how fraction of soil clay-sized particles (clay H) can be estimated using only a single-reading at time t in the hydrometer method, and 2) develop predictive functions to estimate clay H fraction using the particles fraction obtained from hydrometer reading at time t (P t). Particle size distribution (PSD) of samples from 246 Iranian and 61 Belgian soils were determined by the hydrometer method. In addition, the PSD of the 61 Belgian soil samples were determined by the pipette method. Finally, the measured clay H based on the standard procedure of hydrometer was estimated by P t values at times 1, 3, 6, and 24 h using regression analysis. High positive-correlation (correlation coefficient, r = 0.987) was observed between clay H and that of obtained from pipette method. Particle fraction obtained from hydrometer reading at time 6 h (P 6) resulted in the highest correlation with clay H. Among the developed P t -functions, the P 6 -function (Cla y H = 0.965 P 6 - 1.12) represented the highest capability to estimate clay H (coefficient of determination, r 2, of 0.992 and 0.985 for calibration and validation datasets, respectively). The absolute values of clay H were close to that of P 6. However, it is strongly recommended to use P 6 -function to acceptably estimate Clay H , particularly in silty soils. Although the suggested procedure is simple, it is as reliable as the standard hydrometer method for determining the soil clay H content. [ABSTRACT FROM AUTHOR]

Biochar is a product of the thermal treatment of sustainably sourced organics or waste biomass, which enhances nutrient availability and exchangeable cations after soil application. Biochar feedstock is one of the primary factors influencing the availability of exchangeable cations in biochar and soil-biochar mix. However, this influence is not satisfactorily understood due to contrasting data among literature for the cation exchange capacity (CEC) and the lack of standard analysis methods for CEC of biochar and soil-biochar mixtures. Therefore, this research was conducted to assess cation exchange in contrasting soil-biochar mixes, where CEC is measured as (1) the sum of base cations (Na+, K+, Mg 2+, and Ca2+) displaced by ammonium acetate (CEC-BC) and (2) NH 4 + displaced by potassium chloride (CEC-NH 4 +). For the first time, we have evaluated CEC-BC and CEC-NH 4 + in 21 different biochar samples using a modified method. We then used 12 representative biochars with 3 soil types (2% w/w biochar) and provided insights on relative changes in CEC-BC and individual base cations. Some previous studies have indicated a relationship between CEC and surface area and a degree of additivity in the resulting CEC of soil-biochar mixes. However, our study demonstrates an absence of these correlations and a lack of additivity in the representative biochar products. We found that biochar prepared from mixed garden wastes can increase K+ or Ca2+ in loamy or sandy soils and mitigate potential soil sodicity problems in loamy soils. However, a clayey soil may or may not need biochar for the specific purpose of increasing exchangeable cations. Our results revealed that biochar prepared from hardwood or mixed garden waste can retain NH 4 + and deliver it to soil acting as a sink and source for soil nutrients. [Display omitted] • Presence of exchangeable cations in biochar is primarily influenced by feedstock type. • Exchangeable K+ was increased by more than 400% in sandy loam soil after application of 2% w/w biochar. • Hardwood or cellulosic biomass derived biochar increases the cation exchange capacity of clayey soils. • Biochar can help mitigate potential soil sodicity by reducing exchangeable Na+ in loamy soils. • Biochar can store significant NH 4 +, suggesting potential use as a slow-release fertilizer. [ABSTRACT FROM AUTHOR]