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The management of plant wastes and the development of soil quality characteristics have a key role in ensuring the harmony of the agriculture cycle with the environment. By adding the straw of plants directly to the soil as a source of organic matter, time poor soil quality characteristics can be improved. In the study, which was planned as a pot experiment, the effects of increasing the addition of sunflowers straw and maize straw by the increased proportions to clay soil. For this purpose, sunflower and maize harvest residue was added to the soil in 0% control (C), 0.5% (SS0.5 and MS0.5), 1% (SS1 and MS1), 2% (SS2 and MS2), and 4% (SS4 and MS4). Compared to the C, the water stable aggregate value increased by approximately 2.2 and 2.5 times in SS4 and MS4 implementations, mean weight diameter values increased approximately 2.7 and 3.3 times, respectively. In SS4 and MS4 implementations, the available water capacity increased by 80% and 102% compared to the control, respectively, and the modulus of rupture values were decreased by approximately 4.1–4.7 times. The 0.5% and 1% doses of straw implementations did not have great effects on the mechanical properties of the soils. According to the results of this study, 4% straw implementations it has been proven that the addition of SS and MS to the soil that by breaking them into small particles have great importance in rapidly increasing the physical quality of the soils and it can be used as an effective agricultural method. [ABSTRACT FROM AUTHOR]

The present research employs new boosting-based ensemble machine learning models i.e., gradient boosting (GB) and adaptive boosting (AdaBoost) to predict the unconfined compressive strength (UCS) of geopolymer stabilized clayey soil. The GB and AdaBoost models were developed and validated using 270 clayey soil samples stabilized with geopolymer, with ground-granulated blast-furnace slag and fly ash as source materials and sodium hydroxide solution as alkali activator. The database was randomly divided into training (80%) and testing (20%) sets for model development and validation. Several performance metrics, including coefficient of determination (R2), mean absolute error (MAE), root mean square error (RMSE), and mean squared error (MSE), were utilized to assess the accuracy and reliability of the developed models. The statistical results of this research showed that the GB and AdaBoost are reliable models based on the obtained values of R2 (= 0.980, 0.975), MAE (= 0.585, 0.655), RMSE (= 0.969, 1.088), and MSE (= 0.940, 1.185) for the testing dataset, respectively compared to the widely used artificial neural network, random forest, extreme gradient boosting, multivariable regression, and multi-gen genetic programming based models. Furthermore, the sensitivity analysis result shows that ground-granulated blast-furnace slag content was the key parameter affecting the UCS. [ABSTRACT FROM AUTHOR]

Management of nitrogen (N) fertilizer is a critical factor that can improve maize (Zea mays L.) production. On the other hand, high volatilization losses of N also pollute the air. A field experiment was established using a silt clay soil to examine the effect of sulfur-coated urea and sulfur from gypsum on ammonia (NH3) emission, N use efficiency (NUE), and the productivity of maize crop under alkaline calcareous soil. The experimental design was a randomized complete block (RCBD) with seven treatments in three replicates: control with no N, urea150 alone (150 kg N ha−1), urea200 alone (200 kg N ha−1), urea150 + S (60 kg ha−1 S from gypsum), urea200 + S, SCU150 (sulfur-coated urea) and SCU200. The results showed that the urea150 + S and urea200 + S significantly reduced the total NH3 by (58 and 42%) as compared with the sole application urea200. The NH3 emission reduced further in the treatment with SCU150 and SCU200 by 74 and 65%, respectively, compared to the treatment with urea200. The maize plant biomass, grain yield, and total N uptake enhanced by 5–14%, 4–17%, and 7–13, respectively, in the treatments with urea150 + s and urea200 + S, relative to the treatment with urea200 alone. Biomass, grain yield, and total N uptake further increased significantly by 22–30%, 25–28%, and 26–31%, respectively, in the treatments with SCU150 and SCU200, relative to the treatment with urea200 alone. The applications of SCU150 enhanced the nitrogen use efficiency (NUE) by (72%) and SCU200 by (62%) respectively, compared with the sole application of urea200 alone. In conclusion, applying S-coated urea at a lower rate of 150 kg N ha−1 compared with a higher rate of 200 kg N ha−1 may be an effective way to reduce N fertilizer application rate and mitigate NH3 emission, improve NUE, and increase maize yield. More investigations are suggested under different soil textures and climatic conditions to declare S-coated urea at 150 kg N ha−1 as the best application rate for maize to enhance maize growth and yield. [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]

Expansive soil, also called swelling soil can cause severe damage to buildings and foundations due to the high swell-shrink behavior corresponding to moisture content changes. Slag, which is defined as the by-product of the iron and steel-making process, has been widely used as a stabilizer agent for developing clay soil mechanical characteristics. This review paper highlighted the findings of previous studies on treating expansive soils utilizing several types of slag. The effect of mixing slag with other additives such as Portland cement and lime on expansive soil swelling properties was reviewed. [ABSTRACT FROM AUTHOR]

Suction bucket installation in pure clay or pure sand is well established. However, in layered soils, particularly in sand over clay soils, the soil plug uplift is considered a major installation risk and feasibility of installation is often questioned. In this paper, the experience from installation of two suction bucket jackets at two offshore wind farms in layered soils is reported. The installation at both sites was successful and no excess plug uplift was observed. The transfer of suction to the clay-sand interface is believed to have contributed to the success of the installations. The two cases presented in this paper provides confidence in suction bucket foundation installation in similar soil conditions. [ABSTRACT FROM AUTHOR]

The results of the search for and study of the Late Pleistocene soils in the north of Western Siberia are described. The theoretical basis is an ice-free model of the evolution of Pleistocene landscapes in the region, because the alternative model of its glacial cover excludes the preservation of paleosols. Glacial deposits are absent in this region, and paleosol levels are detectable in the sections of high river terraces exposing the Late and Middle Pleistocene sediments. They correspond to the chronointervals with landscape conditions favorable for pedogenesis; namely, soils of the (1) Kazantsevo thermochron (marine isotope-oxygen stage MIS5 overlying the Middle Pleistocene alluvium), (2) Karginsky interstadial (MIS3), and (3) the end of Sartan cryochron (MIS2). The pedogenetic interpretation of these paleosols is based on morphogenetic analysis, including micromorphological examination. According to this analysis, (i) the stage of taiga soil formation with clay illuviation in the polygenetic profile of MIS5 paleosol was replaced by a colder tundra phase with suprapermafrost gleying; (ii) characteristic of the MIS3 paleosols were tundra-steppe conditions, under which gleying and cryogenesis were combined with the neoformation of carbonates; and (iii) the paleosol level of the end of MIS2 was the result of tundra-swamp pedogenesis and included gleyed pedosediments that filled ice-wedge pseudomorphs. The latter fact allows us to identify the Late Sartan Taz–Nadym cryogenic soil horizon. The results are correlated with synchronous stratigraphic schemes for adjacent regions suggesting the construction of the soil–permafrost paleorecord for the north of Western Siberia. This is important, because the interpretation of the modern surface soils requires special approaches in order to take into account relict pedogenic horizons that are often found in their profiles. [ABSTRACT FROM AUTHOR]

Large quantities of steel slag are generated annually throughout the world. Some slag from steel manufacturing is reused in the generation of other materials, such as hot mix asphalt aggregate, pipe filling, concrete, among others. The research aims to enrich the mechanical characteristics of soils and minimize road construction costs. The objective of this research is to find a material that increases the mechanical properties of the subgrade in clay soils with different plasticity indices using Electric Arc Furnace Slag (EAF) in percentages: 5%, 15% and 25% of the weight of the soil. From the tests carried out on the soil samples using parameters, it was possible to classify them by the Unified Soil Classification System (USCS) and also by the American Association of Highway Transportation (AASHTO) as low and high clays. plasticity. When testing the samples in their natural state and the samples with EAF, results were obtained that showed an improvement in the physical and mechanical properties of the clay soils with the addition of EAF, increasing the values of the Bearing Capacity Ratio (CBR) and the maximum dry density. of the clay soil as the percentage of HAE in the mixture increased. The optimal HAE addition content corresponds to 25% of the weight of the soil. [ABSTRACT FROM AUTHOR]

The timing of nitrogen fertilizer application in vineyards can determine the amount of nitrogen (N) absorbed, distributed, and accumulated in grapevine organs. The study aimed to evaluate the annual contribution of N from urea, applied at different times in Cabernet Sauvignon, grown in sandy and clayey soil in a subtropical climate. The sandy soil received 21.42 kg N ha−1 and the clayey soil 30 kg N ha−1, both enriched with 3% excess 15N atoms, applied at different times. The N derived from the fertilizer in grapevines, at all times of N application, and in sandy and clayey soil did not exceed 8%, with the highest values being observed in annual organs, especially in the leaves. The application of N marked at the phenological stages of IBB (50% at beginning of budbreak + 50% at full budbreak) enabled greater absorption of N derived from the fertilizer by the vines grown in both sandy and loamy soil. The N present in the annual organs (leaves, berries, stalks, and shoots) and in the perennial organs (stems and canes) of Cabernet Sauvignon grown in sandy and clayey soil was derived in greater percentages from the soil. [ABSTRACT FROM AUTHOR]

Soil salinization affects more than 25% of land globally. Subsurface pipe drainage is known for its effectiveness in improving saline–alkali land. The red clay layer (RCL) hinders soil improvement in the Hetao Irrigation District of Inner Mongolia, China. The soil water and salt migration rules at different buried depths and RCL were studied based on the field subsurface pipe drainage test and simulation using the DRAINMOD-S model (Version 6.1). The following implications can be drawn from the results: (1) Although the RCL affected the accuracy of the model, the calibrated statistical results met the application requirements, and the DRAINMOD-S model can be used to analyze subsurface pipe drainage under different distribution conditions of the RCL. (2) The RCL can reduce the drainage efficiency of the subsurface pipe, specifically when the distribution is shallow. (3) The soil desalting rate increased with an increase in the buried depth of the subsurface pipe. The desalination effect of shallow soil was better than that of deep soil. The RCL reduced the drainage and salt removal efficiency of the subsurface pipe. Burying the subsurface pipe as far above the RCL as possible should be considered. Thus, it is feasible to apply the DRAINMOD-S model to relevant studies. [ABSTRACT FROM AUTHOR]

Tomato is valued for its nutritional importance and contribution to countries' GDP. Despite the importance of tomatoes, tomato cultivation remains a challenge in some cities, particularly Kumba, Cameroon. This results from a vast knowledge gap for a suitable variety and agronomic management practices. Thus this work was set out to investigate the response of three tomato varieties under organic, foliar, and granular inorganic fertilization at the Kumba I subdivision. This work comprised two factors; variety having three levels (Cobra F1, Rio Grande, and Kiara tomato varieties) and fertilization having four levels (control, NPK 20:10:10 granular fertilizer, Foliar NPK 20:10:10 inorganic fertilizer, and Poultry manure) given twelve treatment combinations replicated three times randomly in a factorial design. Data was collected on soil physicochemical properties, plant growth parameters and fruit yield. The results showed that the variety did not significantly affect soil physicochemical properties, but soil physicochemical properties were significantly affected by fertilization. Poultry manure had the best OC (5.22 %), Ntot (1.73 g/kg), and Pavail (14.63 mg/kg), while K was highest (2.93 meq/100g) in NPK 20:10:10 granular fertilization. Rio grande, in combination with poultry manure, had the best plant growth; plant height (77.3 cm), number of branches (17), number of leaves (197), and leaf area (47.1 cm2). Cobra F1, in combination with foliar NPK 20:10:10 granular and poultry manure, had the best fruit yield; 13.42 tha-1 and 13.56 tha-1, respectively while Kiara variety at the control treatment had the lowest yield (8.36 tha-1). Thus Cobra F1 variety in combination with poultry manure yielded the best result from this study and offers the best option for tomato cultivation in the sandy clay soils of Kumba, Cameroon. [ABSTRACT FROM AUTHOR]

Evidence is emerging that microbial products and residues (necromass) contribute greatly to stable soil organic matter (SOM), which calls for the necessity of separating the microbial necromass from other SOM pools in models. However, the understanding on how microbial necromass stabilizes in soil, especially the mineral protection mechanisms, is still lacking. Here, we incubated 13C‐ and 15N‐labelled microbial necromass in a series of artificial soils varying in clay minerals and metal oxides. We found the mineralization, adsorption and desorption rate constants of necromass nitrogen were higher than those of necromass carbon. The accumulation rates of necromass carbon and nitrogen in mineral‐associated SOM were positively correlated with the specific surface area of clay minerals. Our results provide direct evidence for the protection role of mineral in microbial necromass stabilization and provide a platform for simulating microbial necromass separately in SOM models. [ABSTRACT FROM AUTHOR]

Formation of mineral‐associated organic matter (MAOM) supports the accumulation and stabilization of carbon (C) in soil, and thus, is a key factor in the global C cycle. Little is known about the interplay of mineral type, land use and management intensity in MAOM formation, especially on subdecadal time scales. We exposed mineral containers with goethite or illite, the most abundant iron oxide and phyllosilicate clay in temperate soils, for 5 years in topsoils of 150 forest and 150 grassland sites in three regions across Germany. Results show that irrespective of land use and management intensity, more C accumulated on goethite than illite (on average 0.23 ± 0.10 and 0.06 ± 0.03 mg m−2 mineral surface respectively). Carbon accumulation across regions was consistently higher in coniferous forests than in deciduous forests and grasslands. Structural equation models further showed that thinning and harvesting reduced MAOM formation in forests. Formation of MAOM in grasslands was not affected by grazing. Fertilization had opposite effects on MAOM formation, with the positive effect being mediated by enhanced plant productivity and the negative effect by reduced plant species richness. This highlights the caveat of applying fertilizers as a strategy to increase soil C stocks in temperate grasslands. Overall, we demonstrate that the rate and amount of MAOM formation in soil is primarily driven by mineral type, and can be modulated by land use and management intensity even on subdecadal time scales. Our results suggest that temperate soils dominated by oxides have a higher capacity to accumulate and store C than those dominated by phyllosilicate clays, even under circumneutral pH conditions. Therefore, adopting land use and management practices that increase C inputs into oxide‐rich soils that are under their capacity to store C may offer great potential to enhance near‐term soil C sequestration. [ABSTRACT FROM AUTHOR]

Interactions between adjacent piled-raft foundations may induce additional settlement and cause the tilt of the structure. This case study investigates the long-term performance of a large piled-raft foundation system supporting high and heavy alumina solution storage tanks based on field measurements and three-dimensional (3D) numerical simulations. To properly consider the interactions among rafts, piles, and soils; the elastoplastic behavior of clayey and sandy soils; and the consolidation behavior of soil after construction, a 3D finite-difference code was utilized for the numerical modeling. Two undrained mechanical analyses were conducted to simulate the installation of foundations/tanks and the filling of alumina solution into the tanks, while two coupled hydromechanical analyses were performed to model the period between the two undrained stages and the stage after tank filling, respectively. The predictive capability of the numerical model was checked by comparing the simulation results first with single pile load test data and then with in situ settlement measurements at different locations of the piled-raft foundations. The long-term behavior of the piled-raft foundations was further investigated by analyzing various aspects including the axial force variation along the pile at different locations, the time-settlement relation at monitoring locations, the vertical effective stress increment and displacement of soil, and the differential settlement between monitoring locations. Based on the simulations, the tilt of the platform was mainly due to the superposition of additional stresses near the centerline of the two rows of piled-raft foundations. Finally, parametric studies were conducted to investigate the interactions among the piled-raft foundations at different pile length configurations. The results show that by properly increasing the length of the piles near the centerline of the two rows of piled-raft foundations, the differential settlement of the platforms can be mitigated. [ABSTRACT FROM AUTHOR]

Due to the increase in population, the demand for buildings increases. The engineering properties of the soils on which these structures will be built may not always meet the desired conditions. In such cases, soil improvement methods are used. One of these methods is additive used stabilization, in which additives such as lime, fly ash, volcanic ash and tuff, silica fume, and blast furnace slag are used. This method has been used successfully for years. However, in recent years, interest in the use of different types of fibers has increased. Some of these fibers are glass, basalt, polypropylene, and carbon. Basalt fibers have begun to attract attention in soil reinforcement applications due to the properties of their raw material, basalt rock, which is widely distributed in nature, natural, and has high strength. In this study, the effect of basalt fiber reinforcement on the unconfined compressive strength of high plasticity bentonite clay was revealed. For this purpose, 12 mm long basalt fiber in different proportions (1%, 2%, 3%, 4%, and 5%) was used as reinforcement in bentonite clay, and the optimum fiber ratio that provided the maximum increase in strength was determined. According to the results of the study, when 12 mm long basalt fiber was used as reinforcement in bentonite clay, the maximum strength value was obtained at a 4% basalt fiber ratio. However, the strength value decreased in the sample where 5% BF was used. It has been determined that basalt fiber reinforcement improves the strength properties of bentonite clay. [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]

The use of bacteria-based self-healing concrete for substructures in ground conditions is an area of increasing interest for enhancing the durability and longevity of infrastructure. In line with this objective, the present study investigates the bio-self-healing performance of a cementitious material embedded in clay soil with varying chemical exposures and water saturation regimes. Laboratory experiments were conducted on pre-cracked mortar specimens with Bacillus subtilis encapsulated in perlite. The specimens were incubated in the soil with different pH and sulphate levels, representing three exposure classes (based on Eurocodes). The crack healing ratio was evaluated through visual inspection and capillary-water absorption—before and after soil incubation. Findings showed that all inoculated specimens exhibited healing ratios noticeably larger than those of the control specimens, which mainly experienced small autogenous healing. Of note, the best healing performance was observed when the soil was fully saturated and pH-neutral. From the design perspective of bio-concrete, this study emphasizes the consideration of groundwater regime as well as acidity and sulphate of the soil. [ABSTRACT FROM AUTHOR]

This study investigates the stabilization performance of clayey soil treated with alkali-activated hybrid slag/cement. Sodium silicate (SS) and sodium hydroxide (SH) are used as alkali activators, whereas ground blast furnace slag (GGBS) and ordinary Portland cement (OPC) are used as sources of aluminosilicate. A total of 27 different types of mixtures are used for stabilization. Unconfined compressive strength (UCS) of untreated clay and stabilized soils are performed at immediately, 3-, 7-, 28-, and 90 days curing times under air-dried and wet-cured conditions. In addition, 90-d volume and mass changes in the samples are measured. Stabilized samples with an SS/SH ratio of 1 under air-dried conditions reveal moistening at early curing ages (=28 days); afterward, sodium carbonate crystals appear in these samples at longer curing ages. Geopolymer-treated clayey soil exhibits lower volumetric and mass changes compared with OPC. Most of the stabilized clayey soil with alkali-activated hybrid slag/cement exhibits higher strength compared with OPC under air-dried and wet-cured conditions. [ABSTRACT FROM AUTHOR]

This paper aims to improve the strength of soft clay soil using thermal treatment through a laboratory study that simulates the field application. The laboratory work consisted of preparing a soft clay (Cu = 14 kPa) inside a metal box (92.5 × 92.5 × 92.5) cm3. Boreholes of diameter 43 mm, with different lengths, spacing, and arrangements, were made inside the soil to work as a guide for heating pipes which connected to a controlled heating system. A novel heating system, using gas as a heat source, was developed and manufactured. After the end of the treatment periods, a load was applied until failure on a (20 × 20) cm2 square footing. Various parameter spacings (3, 4, and 5 times the outer diameter of the borehole), depths (1, 1.5, 2, and 2.5 times the width of the model footing), arrangements (square, circular, and triangular), and heating periods (2, 4, 6, 8, and 10 h) were investigated. The results showed the strength and behavior of the soil when subjected to the heated boreholes at different spacings, depths, and heating times, which were determined to be three times the outer diameter of the borehole, two times the width of the square footing, and eight hours, respectively, while the effect of the arrangement of the heated borehole casings was small. Also, a cone penetration probe (CPT) conducted on the heated soil showed that the unconsolidated shear strength (Cu) increased from 14 to 360 kPa and then decreased to 140 kPa (as an average with depth). In contrast, the average angle of internal friction (Ø) increased from 0 to 52 degrees and decreased to 16 degrees (as an average with depth) from the center of the heating model to the furthest point affected by heating. The EDS formula showed that components such as silicon, aluminum, and iron decreased at 300 °C and increased at 400 °C in the treated soils. The calcium content increased at 200 °C and then decreased sharply at 400 °C. The carbon percentage increased at 300 °C and decreased at 400 °C. The elemental proportions showed little change or remained stable at temperatures between 400 °C and 600 °C. [ABSTRACT FROM AUTHOR]

This document serves as a follow-up to a previous paper on the use of lime and rice husk ash (RHA) to stabilize clayey soil. The original paper found that the addition of lime and RHA increased the strength of the soil, with the highest strength observed in samples containing 7% lime and 12% RHA. The document also includes additional research studies that support the use of RHA to improve soil strength. These studies found that the inclusion of RHA increased the California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) values of the soil, with the maximum strength achieved at an optimal RHA content. The increase in strength was attributed to the formation of cementitious products and agglomeration of soil particles. The degree of strength development varied depending on the type of soil and RHA used. The article also suggests future research directions, such as considering the effect of dry density and evaluating the suction effect. [Extracted from the article]

This document is a discussion of a research paper titled "Probing the Stochastic Unconfined Compressive Strength of Lime–RHA Mix Treated Clayey Soil." The paper explores the use of lime and rice husk ash as binders to stabilize clayey soil. The authors conducted tests to measure the unconfined compressive strength of soil-binder specimens with varying amounts of rice husk ash and lime. They used artificial neural networks and Gaussian process regression to analyze and predict the data. The discussers raise questions about the influence of suction on the strength of the blends and the effect of dry density, suggesting further evaluation of these factors. [Extracted from the article]

Tacca chantrieri André (1901) is a valuable evergreen rhizomatous herbaceous species that plays a crucial ecological and economic role in Vietnam's evergreen broadleaf forests. However, the degradation of forest ecosystems poses a significant threat to its survival in the wild. This study aimed to develop a model for determining the potential land suitable for Tacca chantrieri in Ba-Vi Natural Park, utilizing SoilGrid data. The results revealed that the species primarily thrives in Ba Vi, Minh Quang, and Yen Bai communes, covering approximately 20.92% of the total area. Despite its adaptability, Tacca chantrieri is highly scarce in the wild, with only 30 identified population spots concentrated along streams and slopes. The Jackknife standard analysis identified five key variables influencing the potential distribution of Tacca chantrieri in Ba-Vi National Park: clay composition in soil (36.9% contribution), bulk (22.6%), organic carbon density (OCD) (16.4%), coarse fragments (CF) (13%), and silt (9.3%). These findings highlight the applicability of SoilGrid data in species distribution modeling for small areas, particularly in the absence of site-specific soil data. However, for precise and site-specific information, field data collection remains indispensable. The high AUC values (training data: 93.9%, test data: 94.9%) indicate the feasibility of developing an effective model for evergreen rhizomatous herbaceous species. [ABSTRACT FROM AUTHOR]

Expansive clay soils, characterized by their propensity to undergo significant volume changes in response to moisture variations, present considerable challenges in construction engineering. These challenges manifest as structural damage, including fractures, asymmetrical settlements, and erosion. This study investigates the application of sustainable waste materials, specifically a mixture of plastic and glass waste, as an innovative approach to soil stabilization. In the context of Anbar, Iraq, laboratory experiments were conducted to evaluate the efficacy of incorporating plastic and glass waste in various proportions (0%, 4%, 5%, 6%) into clayey soil. The primary focus was to assess changes in geotechnical properties, notably the reduction in swelling potential and alterations in the maximum dry unit weight of the soil. Results indicated that the inclusion of waste materials in the specified proportions significantly mitigated the soil's swelling behavior, with reductions of 2%, 3%, and 5% observed for the respective waste content. Concurrently, enhancements in soil density were recorded, with increases in the maximum dry unit weight by 4%, 5%, and 9% corresponding to the same proportions of waste additives. These findings underscore the potential of using recycled waste materials in soil stabilization, aligning with environmental sustainability goals through the repurposing of waste. Additionally, this approach offers an economically viable alternative to traditional stabilization methods. The utilization of waste materials not only addresses the environmental impact of construction activities but also contributes to the broader goal of waste management and resource conservation. [ABSTRACT FROM AUTHOR]

Termites contribute to the spatial heterogeneity of the ecological processes of the highly degraded lands called the bowé in West Africa, but the underlying determinants of the distribution of the mounds remain poorly understood. Thus, the study aims to determine the principal abiotic and biotic factors shaping mound densities on bowé in Benin, West Africa. A number of 64 plots were randomly sampled on sites with mounds and adjacent off‐mounds sites on bowé. Data were collected on abiotic (soil variables (pH, bulk density, particle sizes and soil organic carbon) and altitude) and biotic (the number of live termite mounds, plant richness and cover) factors. Correspondence analysis (CA) was applied to assess the pattern of vegetation and termite mounds on bowé; while principal component analysis (PCA) was used to assess the relationship between soil variables (pH, bulk density, particle size and soil organic carbon), altitude, number of mounds, plant richness and cover. Generalised mixed effects and linear mixed effects models with Poisson error distribution were used to analyse the variation in soil variables, number of mounds, species richness and cover between termite species. The findings revealed that the pattern of termite mounds on bowé was driven by altitude (topography) and soil clay content that contribute to termite activities as well as improving soil bulk density, plant species richness and cover. These factors were positively associated with all termite species considered, except for those belonging to the genus of Macrotermes. [ABSTRACT FROM AUTHOR]

Background: Soil organic carbon stocks (SOCs) play a critical role in supporting soil quality and ecosystem functions. Information on SOCs content in coastal lands is scanty and the types of clay minerals and soil fraction size that affect SOCs are still debated. We evaluated the SOCs content and identified the mineral type and soil fraction affecting the SOCs on coastal land. Methods: Soil samples were collected from each layer of nine different soil profiles in three subdistricts: Seunuddon (SD), Lapang (LP) and Dewantara (DT) in Aceh Utara Regency of Indonesia. The soil profiles were taken from different distances (300, 900 and 1500 m from the shoreline-d.f.s). Result: The results revealed that SOCs possessed by each soil layer of coastal land in Aceh Utara varied between 0.64 to 43.45 MgC ha-1. The highest to lowest average total of SOCs content for the location is SD>DT>LP, while for the position, the distance to the shoreline is 900 m>1500 m>300 m. Clay minerals such as labradorite, smectite, vermiculite and chlorite positively increase the SOCs content. Very fine sand is a size of the soil fraction that affects the increase in the levels of SOCs in coastal land. [ABSTRACT FROM AUTHOR]

This study was necessary because in Peru the application of resources such as artificial intelligence in the optimization of treatment doses in soil stabilization is not promoted. The purpose of the study was to evaluate the influence of the application of an artificial intelligence model on the optimization of the dosage of natural hydraulic lime, plastic and metallic fibers on the geological characteristics of a gravelly clay soil. The dosages of stabilizers and laboratory tests were used as input variables (predictors) and the values of mechanical tests as output variable. As main conclusions, an interesting application in terms of additive optimization was demonstrated in comparison with experimental results in the field. The model suggests a reduction of predominant materials, such as lime, to obtain acceptable results based on actual test results. The implications of including artificial intelligence, achieves substantial strength maintenance superior to the natural sample of 6 times, respectively, with an optimization of 4% natural lime, 2.25% plastic fiber, 10% metallic fiber and 83.75% natural soil. It is concluded that the influence of applying the artificial K-OPLS model on the real experimental dosages, implies in the reduction of lime up to 50% less, and the increase of plastic fiber in 0.75% more, the metallic fiber maintains its real dosage and the natural soil varies slightly. [ABSTRACT FROM AUTHOR]

Trace elements (Co, Cr, Mn, Mo, Ni, Rb, Th, U, and V) in surface soil of AlAslah (NH1), Nasiriyah refinery (NH2), Gharraf (NH3), and Tall Al-Laham (NH4) at Thi-Qar governorate, southeast Iraq, were studied. The study aims to detect their distribution and pollution levels to reduce the subtracted from industrial sources and avoid using contaminated areas for agricultural purposes before the soil treatment process. Inductivity Coupled Plasma Mass Spectrometry (ICP-MS) technique was used to determine the concentrations of these elements, and the results showed that there is a high concentration of Cr, Ni, Mo, and Mn in the soil of the study area, which exceeded the international levels compared with other elements (Co, Th, U, and V). The Geo accumulation index (I geo) values showed that the soil area was classified as low contamination in all sites and for all trace elements except for Mo, which is polluted in Al-Gharraf and strongly polluted in Tall Al-Laham. The values of the enrichment factor (EF) were indicated to be minimal enrichment of (Mn and V) in all sites and moderate enrichment of (Co) in all sites except in the Gharraf soil sample, which is considered as minimal enrichment. At the same time, it suffers from significant enrichment of (Cr) in all sites. The values of contamination factor (CF) showed extreme contamination of Cr and Ni in all sites due to the oil industry (Nasiriyah refinery), except for Ni in the Gharraf soil sample, which is considered as high contamination and moderately contamination with Co in all sites, and low contamination with Mn and V. The main cause of the increasing trace element concentrations in the study area that the samples located in industrial sites where trace elements are one of the waste products from fuel combustion from the oil fields and the waste of the brick factories near the study area, also the nature of the study area soil which is clay soil that absorb the trace elements on its surfaces. [ABSTRACT FROM AUTHOR]

Current ware potato yields in the Netherlands are approximately 70% of their potential. It is hypothesised by several stakeholders within the potato value chain that part of the potato yield gap is caused by a lack of phosphorus (P) and potassium (K) application. In this study, we analysed for 46 farmers' fields if increasing P and K fertiliser application rates led to a higher yield and yield quality. We found that, on average, increased P and K fertiliser application did not result in a significantly higher yield for two currently cropped potato cultivars on two different soil types in the Netherlands (Innovator on clay soils and Fontane on sandy soils) and in two years (2019 and 2020). However, on sandy soils at relatively lower farmer K application rates, our K application led to a small positive yield response up to 5 t ha−1. On clay soils, there was an average positive yield response to our K application at lower yield levels of the control. For P, we did not find any correlation between yield response to P application and the amount of P applied by farmers or any of the measured soil parameters. In terms of yield quality, the K application led to a slight reduction in underwater weight on sandy soils in 2019 and a slight increase in the yield of large tubers in 2020. We conclude that, although in some fields there was a small positive yield effect of increased K application, increasing P and K application rates will not narrow the potato yield gap and improve potato yield quality in the Netherlands. Instead, increasing the P and K application will decrease P and K use efficiency and hence is not recommended from an environmental and economic perspective. [ABSTRACT FROM AUTHOR]

The capillary pressure curve is a crucial basis for studying the pore structure and multiphase flow characteristics in oil and gas reservoirs. Due to the loose and unconsolidated nature of the clayey-silt sediment of natural gas hydrate reservoirs in the South China Sea, conventional methods such as mercury intrusion and centrifugation struggle to obtain capillary pressure curves for these sediments. In this study, X-ray diffraction analysis, scanning electron microscopy, nitrogen adsorption, and water-gas contact angle measurements are utilized to characterize the mineral composition, pore structure, pore size distribution, and wettability of the clayey-silt sediment. Subsequently, the filter paper method from soil mechanics is employed to determine the capillary pressure curve for the clayey-silt samples. The results indicate that the capillary pressure curve obtained through the filter paper method exhibits a saturation range of 18.39%-80.31% and a capillary pressure range of 19.04 to 46,481.42 kPa. It exhibits a distinct two-stage characteristic, where capillary pressure changes rapidly with water saturation below 61.05% and slowly above 61.05%. The pore radius calculated from the capillary pressure curve ranges from 2.41 nm to 5.91 µm. This alignment with the pore ranges obtains from nitrogen adsorption and Scanning Electron Microscopy confirms the accuracy of the obtained capillary pressure curve. Furthermore, in comparison with a literature capillary pressure curve obtained through centrifugation, the paper filtration method covers a broader range, providing better representation of capillary pressure in the multiscale pores of clayey-silt samples. [ABSTRACT FROM AUTHOR]

Tropical pasture legumes such as Desmanthus are expected to improve pasture productivity in the extensive grazing systems of Northern Australia. However, the soils in these areas are often hostile (e.g., hard-setting and nutrient-deficient), which reduces legume emergence and establishment. Furthermore, these soils are often not ameliorated with amendments such as gypsum or starter fertilisers before planting. A pot trial was conducted to investigate differences in the emergence and early growth of four Desmanthus species. The legumes were grown in three alkaline clay soils that were unamended or amended with either gypsum (1 t CaSO4.2H2O ha−1 equivalent), a starter MAP fertiliser (12 kg P ha−1 equivalent), or both gypsum and the starter fertiliser. Seedling emergence was recorded daily and shoot yield was determined after six weeks' growth. Final seedling emergence (as a percentage of viable seeds) varied among the Desmanthus species (c.f. D. leptophyllus = 63%, D. pernambucanus = 68%, D. bicornutus = 85%, and D. virgatus = 86%). On average, across the treatments, gypsum increased seedling emergence by 15%, whereas the starter fertiliser had no effect. The shoot yields and shoot phosphorus content of the Desmanthus species generally increased in response to the starter fertiliser. The collective results demonstrated that there were differences in emergence and early growth among the four Desmanthus species, which indicates that Desmanthus cultivar selection may be important in the relatively hostile soils of Northern Australia. Gypsum was an effective amendment for seedling emergence, whereas the starter fertiliser was an effective amendment to increase legume productivity. [ABSTRACT FROM AUTHOR]

Acquiring comprehensive insights into soil properties at various spatial scales is paramount for effective land management, especially within small catchment areas that often serve as vital pastured landscapes. These regions, characterized by the intricate interplay of agroforestry systems and livestock grazing, face a pressing challenge: mitigating soil degradation while optimizing land productivity. This study aimed to analyze the spatial distribution of eight topsoil (0–5 cm) properties (clay, silt, sand, pH, cation exchange capacity, available potassium, total nitrogen, and soil organic matter) in a small grazed catchment. Four machine learning algorithms—Random Forest (RF), Support Vector Machines (SVM), Cubist, and K-Nearest Neighbors (kNN)—were used. The Boruta algorithm was employed to reduce the dimensionality of environmental covariates. The model's accuracy was assessed using the Concordance Correlation Coefficient (CCC) and Root Mean Square Error (RMSE). Additionally, uncertainty in predicted maps was quantified and assessed. The results revealed variations in predictive model performance for soil properties. Specifically, kNN excelled for clay, silt, and sand content, while RF performed well for soil pH, CEC, and TN. Cubist and SVM achieved accuracy in predicting AK and SOM, respectively. Clay, silt, CEC, and TN yielded favourable predictions, closely aligning with observations. Conversely, sand content, soil pH, AK, and SOM predictions were slightly less accurate, highlighting areas for improvement. Boruta algorithm streamlined covariate selection, reducing 23 covariates to 10 for clay and 4 for soil pH and AK prediction, enhancing model efficiency. Our study revealed spatial uncertainty patterns mirroring property distributions, with higher uncertainty in areas with elevated content. Model accuracy varied by confidence levels, performing best at intermediate levels and showing increased uncertainty at extremes. These findings offer insights into model capabilities and guide future research in soil property prediction. In conclusion, these results urge more research in small watersheds for soil and territorial management. [ABSTRACT FROM AUTHOR]

Sang Yod Phatthalung rice is indica rice and grown as Geographical Indications (GI) in Patthalung province. Its dark red color seed contains high antioxidant activity that helps reduction in the risk of some chronic diseases such as diabetes, cancer, and cardiovascular diseases. So far, yield per planting area of this rice is still low. Thus, application of PGRs might play an alternative role in agronomical and physiological characteristics leading to improving yield of this rice. First, shoot tips of Sang Yod Phatthalung rice were cultured to induce multiple shoots and root on liquified PGR-free oil palm culture medium (OPCM) with different concentrations of 6-benzyladenine (BA) (0, 0.5, 1, 1.5 mg/L) alone or in combination with 1-naphthaleneacetic acid (NAA) (0 and 0.5 mg/L). Complete plants were acclimatized to field condition at Phatthalung Rice Research Station (PRRS). After acclimatization for 120 and 140 days, some agronomical and physiological characteristics of rice plant obtained from different PGR containing OPCM were statistically compared. A 2×4 factorial design in RCBD with 4 replication was performed. The results were clearly demonstrated that adding BA in the culture medium increase plant height, number of panicles, panicle length and leaf chlorophyll content. Plantlets obtained from in vitro culturing shoot tip on 0.5 mg/L BA containing medium gave the highest results in average plant height at 189.50 cm, number of panicles at 34.00 panicles, panicle length at 32.50 cm and leaf chlorophyll content at 39.65 SPAD unit. The results from this present study indicated the production of new plant types or characteristics for Sang Yod Phatthalung rice for high yield in future. [ABSTRACT FROM AUTHOR]

Piles as onshore and offshore foundation structures are often horizontally loaded. The usual calculation method for the behaviour of piles under such loads is the p‐y method. For piles in cohesive soil, several p‐y methods are proposed in literature, leading in general to differing results. A finite element model dealing with the behaviour of horizontally loaded piles in clay soils was established and validated against field tests. Utilising the results of a vast number of numerical simulations, a new p‐y method was developed, which gives reasonable results over the entire range of possible loads for piles of almost arbitrary diameters and embedded lengths in clay soils of varying consistency. The method requires in total six soil parameters and accounts for the actual deflection of the pile and also the effect of pile tip shear resistance by iteratively adapted y‐multipliers which depend on the course of the deflection line and the distance of the considered point to the pile tip. The new method can be generally used for calculation of the bearing behaviour of piles in soft clay under monotonic loading and can serve as a reference for consideration of cyclic load effects or softening effects in stiff clays. [ABSTRACT FROM AUTHOR]

Evaluation of soil sustainability should take into account chemical and mineralogical changes due to cultivation. Potassium (K) application is a key farming practice that may potentially affect phyllosilicate composition and soil properties. Irrigation is another agent that affects soil composition. This study aims to evaluate the imprints of cultivation on the chemical and mineralogical compositions of lowland soils under semi-arid and Mediterranean climate regimes and to assess them with the natural pedogenesis. The sites examined include two permanent plot experiments with crop rotation, and three single-plant plots. Cultivated, control, and fallow soils were analyzed for their chemical and mineralogical composition. The X-ray diffraction patterns of the clay fraction were decomposed to achieve quantitative detection of changes among the illite–smectite (IS) phases and in kaolinite amounts. In loamy and clayey soils dominated by IS phases, cultivation caused minor changes and diverse behavior of the IS phases. Yet, the K balance was negative under high fertilization levels and higher plant mass production. Fertilization enhanced the natural process of transforming IS into kaolinite and illite in the sandy soil, leading to a positive K balance. This study emphasizes the importance of IS minerals as a dynamic K pool that responds to plant needs. [ABSTRACT FROM AUTHOR]

Moisture migration in unsaturated soils is a result of the interaction between temperature and soil microstructure. In order to reveal the mechanism of moisture increase of subgrade soils under diurnal cycle conditions, a series of macro and microscopic tests were carried out on the unsaturated silty clay and sand soil, including liquid–vapor mixed migration tests simulating a one-dimensional subgrade, environmental scanning electron microscope (ESEM), and matrix suction test. Then, the soil microstructure in microscopic images was investigated using the particle (pores) and cracks analysis system (PACS). Next, the relationship between the thermal effects of the soil–water characteristic curve (SWCC) and changes in soil microstructure was analyzed. Finally, the change mechanism of liquid–vapor mixed migration based on the change in soil microstructural under thermal effects was analyzed. The results showed under the diurnal cycle, both the silty clay and sand soil columns appeared in the phenomenon of a "diurnal cycle of water vapor migration", which led to moisture accumulation at the top of the soil layer. In silty clay soil column, moisture was primarily driven by water vapor pressure and migrated upwards. Additionally, moisture redistribution led to changes in soil microstructure, which in turn influenced the process of moisture migration. The moisture content in the upper soil layer increased making both inter-aggregate and intra-aggregate pores decrease. The moisture content in the lower soil later decreased, leading to the water-holding capacity of the lower soil layer to increase. So, the moisture migration gradually decreased at night. In the sand soil column, moisture migration was mainly driven by gravity potential and migrated downwards. Moisture redistribution made inter-aggregate pore and matrix suction of the upper soil layer increase, leading to an increase in moisture migration at night. [ABSTRACT FROM AUTHOR]

Foundation plays a vital role in weight transfer from the superstructure to substructure. However, foundation characteristics such as pile group, piled raft, and footing remain unfolded due to their highly non-linear behaviour in different soil types. Bibliography analysis using VOSvierwer algorithm supported the significance of the research. Hence, this study investigates the load-bearing capacity of different types of foundations, including footings, pile groups, and piled rafts, by analyzing experimental data using finite element tools such as PLAXIS 2D and GEO5. The analysis involves examining the impact of various factors such as the influence of surcharge and the effect of different soil types on the load-bearing capabilities of the different types of foundation. For footing, parametric investigations using PLAXIS 2D are conducted to explore deformational changes. Pile groups are analyzed using GEO5 to assess their factor of safety (FOS.) and settling under various criteria, such as pile length and soil type. The study also provides insight into selecting the right type of foundation for civil engineering practice. Findings showed that different soil types have varying deformational behaviours under high loads with sandy soil having less horizontal deformation than clayey soil. Also, it was observed that increasing the pile thickness by 50% resulted in a reduction of 13.88% in settlement and an improvement of 16.66% in the FOS. In conclusion, this study highlights the importance of professionalism, exceptional talent, and outstanding decision-making when assessing the load-bearing capabilities of various foundation types for building structures. [ABSTRACT FROM AUTHOR]

The paper investigates the effect of hydrated lime on shear strength properties and behaviour of London clay, triaxial. Unconsolidated undrained tests were performed to identify the effect of lime dosage, compaction water content and curing time on the shear strength and stress–strain behaviour of the treated soil. The mineralogical and physicochemical transformations occurring during the curing of the soil were also monitored. The results showed that strength gain was strongly influenced by lime content and the curing period, whereas compaction water content was less influential. It was found that the strength evolution is likely to continue over long periods of time and result in very considerable strength gains on the hardening of pozzolanic reaction products. It was also shown that adequate early strength gains can be obtained with reduced material consumption, thus further increasing the sustainability of the treatment processes. The paper also highlighted the importance for engineering design of considering the brittle stress–strain response of the lime-treated soil, and the benefit of using lower amounts of lime to alleviate this undesirable effect. The implications of various aspects of soil brittleness in different situations merit further attention and should be explored by way of modelling in future work. [ABSTRACT FROM AUTHOR]

Clay minerals in soils and rocks exhibit large volume change upon interaction with water and this behavior becomes even more complex when the strata are being stressed by the engineering and environmental loads. Therefore, a realistic prediction of the hydro-mechanical behavior of the clay-bearing strata is always a challenge due to their coupled swelling-mechanical response in the cases of geotechnical and geoenvironmental engineering problems, nuclear waste storage in clay-bearing rock repositories, shale gas extraction, and other uses of clay in the manufacturing industry. All the existing behavior models have restricted applications in the engineering and other fields of practice mainly due to the partial consideration of the structure and fabric of clay-bearing strata in the model formulation. In this study, a hydro-mechanical behavior model has been formulated using the parameters acquired from the molecular-level simulations and modeling of the volume change and stress–strain behavior of the clay-bearing structure. The Molecular Mechanics and Molecular Dynamic simulations were performed on the natural structure of the clay-bearing strata formulated using Monte Carlo technique. The mathematical model, developed from the simulation results, can predict the overall hydro-mechanical behavior of clay-bearing strata for all possible combinations of clay minerals, non-clay minerals, salts causing cementation of the soil/rock structure, confining pressures, and the induced strain levels. The developed model has successfully been validated through laboratory and field testing on the clay-bearing strata in both the elastic and elasto-plastic regions of the stress–strain behavior and also from the data of two (02) swelling clays (MX-80 and FEBEX Bentonite) from the existing literature, supporting the universal nature of the developed behavior model. [ABSTRACT FROM AUTHOR]

Coastal clayey soil has a great potential for food production and safety while poor physico-mechanical properties have impeded its sustainable utilization. A field experiment was conducted to assess the influence of biochar on physicomechanical properties of coastal clayey soil. The biochars were applied to the coastal soil with the rate of 0, 1%, and 3% (w/w), respectively. Compared with control treatment, the application of three biochars (at the rate of 3%) had significantly improved soil fertility, i.e. organic carbon, total nitrogen, available nitrogen and available phosphate, respectively. Biochar treatments significantly increased soil porosity, and aggregates stability, while reduced the soil salinity compared to the control treatment. Meanwhile, biochar application significantly increased the plastic index of coastal clayey soil while decreased soil tensile strength and shrink swell properties compared to the control. Biochar clearly altered soil pore characteristics, consequently rebuilding the new ions leaching channels. Overall, the cow manure biochar (650 °C) at the rate of 3% treatment showed maximum efficiency on soil salinity, fertility, physicomechanical properties, and crop yield. The biochar amendment improved coastal soil by ameliorating soil pore space and structure, improving soil tillage operation and rice yield, decreasing salt stress, and reducing mechanical strength. [ABSTRACT FROM AUTHOR]

The effects of soil texture on trace metal concentrations and geochemical fractions in an apple orchard soils were investigated. For this purpose, soil samples were taken from the apple orchards with two different soil textures located on the same geomorphological unit in Çanakkale, Turkey. A wet digestion was used to determine total trace metal concentrations, and a sequential extraction method was used to determine geochemical fractions of the metals. According to average total concentrations of all metals, except Pb, were found to be significantly higher (p < 0.05) in clay soils. Sequential extraction analysis showed that potential mobile fractions were ordered as Cd (68.8%) > Pb (52.4%) > Cu (42.0%) > Zn (34.8%) > Ni (32.3%) > Cr (22.9%) in clay soils and as Cd (61.6%) > Pb (51.6%) > Cu (40.2%) > Zn (30.7%) > Ni (30.8%) > Cr (24.9%) in loamy soils. The results revealed that all metals, except Pb, in exchangeable/acid soluble, oxidizable and, potential mobile fractions were found to be significantly higher in clay soils (p < 0.05). It was figured out that clay contents played an effective role in total concentrations of metals and their distribution in geochemical fractions. [ABSTRACT FROM AUTHOR]

Phytoremediation of arsenic (As) by Pteris vittata (P. vittata) is a cost-effective and environmentally friendly method for restoring As-contaminated sites. However, the phytoextraction efficiency is low in some cases, such as clay soil, thus biochar was applied to enhance the efficiency of As extraction. The paper investigated the effect of biochar on soil characteristic, As mobility, and As uptake in P. vittata with a 90-day greenhouse experiment. Biochar derived from rice straw was added at rates of 0.5, 1.5, and 4% (w/w). The results showed that, under biochar amendment, soil pH raised from 5.24 to 6.03 and 4.91 to 5.85, soil dissolved organic carbon (DOC) increased 11.1–46.1% and 2.8–11.2%, respectively, in rhizosphere and bulk soils. Biochar also increased soil catalase (CAT) activity significantly, especially for the rhizosphere soil. Besides, biochar increased the labile As in the soils and transfer coefficient from roots to aboveground, thereby enhancing As accumulation by P. vittata tissues. The accumulation of As in fronds of P. vittata was up to 350 mg kg−1 in 1.5% biochar, which was more than twice the control and far beyond other biochar treatments. The results indicate that biochar addition is favorable to improve phytoremediation of P. vittata in As-contaminated soil and 1.5% (w/w) biochar may be a reasonable application ratio, thus providing an effective solution to enhance the efficiency of As phytoextraction. Biochar increased soil catalase activity in the rhizosphere of P. vittata. Biochar increased the labile concentration of arsenic in soil and arsenic accumulation in P. vittata significantly. Combining biochar and P. vittata reduced arsenic in soil. Biochar amendment was favorable for phytoremediation of P. vittata in arsenic-contaminated soil. [ABSTRACT FROM AUTHOR]

Adhesion between track shoes and clay soil has a significant effect on vehicle track-terrain interaction. To correctly evaluate the adhesion between track shoes operating on clay soil, tri-axial shear test (TST), traction test (TT) and direct shear test (DST) were performed on clay loam (C), sandy loam (S) and loamy clay (L) under different moisture contents (w), shear rates (v) and normal loads (σ). In the TST, the effect of w on cohesive strength and internal friction angle was investigated. Cohesive strength initially increased rapidly with the increase of w then decreased slowly when w reached the plastic limit (PL). Internal friction angle decreased gradually as w increased and then decreased sharply when w ＞PL. In the TT, shear strength increased slowly with the increase of shear rate (v) and then stabilized. In the DST, shear strength increased linearly with the increase of normal load (σ). Thereafter, soil shear strength equation considering w , v and σ was modified based on the results of TST, DST and TT. On this basis, considering the structural parameters of track shoe, adhesion models were developed and verified. The predicted and measured values of normal adhesion and tangential adhesion on C, S and L had strong linear correlations with the coefficients of determination ranging from 0.9665 to 0.9932, and the relative errors were 2.56%, 3.16% and 2.67%, indicating that model derivation and correction were effective. The proposed adhesion models can therefore provide a theoretical basis for the desorption design of track shoes for operation on clay soils. • The novel adhesion models for track shoes operating on clay soils were proposed. • Soil shear strength model considering moisture content, shear rate and normal load. • The interaction mechanism between track shoes and clay soils was analyzed. • The laboratory tests verified the novel adhesion models. [ABSTRACT FROM AUTHOR]

In‐depth knowledge about the impact of organic matter (OM) on soil water vapor sorption (SWVS) and associated hysteresis related to various water activity (aw) levels is limited. The objective of this study was to elucidate the effect of OM on SWVS and sorption hysteresis for different aw levels. We measured water sorption isotherms and physicochemical properties of eight soils with varying clay (6%–47%) and OM (2.0%–7.8%) contents before and after OM removal. In general, OM increased SWVS, but the effect of OM on SWVS varied for different aw ranges. The presence of OM generally increased water vapor sorption during the adsorption process. For soils with OM content above 4.6%, the presence of OM decreased water vapor sorption during the condensation process. The local hysteresis (Hw) of soils with OM was higher than that of soils without OM for soils with OM contents above 3.4%. For aw < ∼0.75, the water vapor sorption hysteresis of soils with and without OM showed a significant correlation with cation exchange capacity (CEC), and the Hw values of soils with OM were lower than that of soils without OM for the same CEC. The OM can affect water vapor sorption and the associated hysteresis at low aw levels through adsorbed cations and organic functional groups, and at high aw levels through the structures of pores and OM. Core Ideas: An increase in water vapor sorption due to OM mainly occurred during adsorption.A decrease of water vapor condensation due to OM is caused by a reduced pore volume.The OM content affects water vapor sorption hysteresis.The CEC is a key factor affecting sorption and hysteresis in soils with and without OM. [ABSTRACT FROM AUTHOR]

In addition to creating environmental threats, the leakage and entrance of chemical fertilizers into soil, which is possible in various ways, dramatically changes the physical and mechanical properties of soil. Furthermore, clay soils in the vicinity of monoammonium phosphate (MAP) contamination show substantially negative behavior, thus, improving the engineering geological factors of soil has become a huge challenge for engineers. Extensive programs such as triaxial compression test, consolidation test, compaction test, Atterberg limits, and collapse tests, in addition to X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were performed on samples containing 10%–30% MAP over 7 days, 1, and 3 months. The mentioned trend was repeated when 0.5%–3% nano A (Al2O3 in alpha phase), nano F (Fe2O3 in alpha phase), and AF in form of a nanohybrid were added to soil which had been contaminated by MAP. Gained reports demonstrated significant declines in maximum dry density, plasticity index, and shear strength of contaminated soil when compared with natural soil. Conversely, increases in liquid limit, plastic limit, consolidation settlement, as well as soil collapse index were observed. Furthermore, a decrease in the amount of minerals in the XRD results and the formation of a flocculated structure in the SEM images in MAP-contaminated soil are evident. According to microstructural analysis, adding nano A, nano F, and AF nanohybrid as an improvement phase caused remediation of the soil structure and created cementation bonds between soil particles, thereby increasing the maximum dry density and soil shear strength, and decreasing the consolidation settlement and soil collapse index. Therefore, the use of AF as an efficient additive to remediate physical and mechanical properties of soils that have been contaminated with MAP, and to decrease the geological hazards of these kinds of contamination is recommended. [ABSTRACT FROM AUTHOR]