Search

AbstractThe significance of zinc and iron in crop production, particularly in rice-wheat cropping systems, has been increasingly recognized. The present study aimed to determine the effect of different soil samples collected from the rice-wheat cropping system of Haryana with different soil texture on rice grain yield and micronutrient content using a greenhouse trial with four levels of Fe (0, 25, 50 mg kg−1 as soil and 0.5% foliar spray of FeSO4 at 45 DAS) and four levels of Zn (0, 5, 10 mg kg−1 as soil and 0.5% foliar spray of ZnSO4 at 35 DAS). This study discovered that rice grain yield showed a positive correlation with soil Zn and Fe concentrations in soil before sowing and a negative correlation with soil Fe and Zn concentrations in soil after crop harvesting. In most of the soils studied, foliar spray alone Fe @ 0.5% foliar (45 DAS) and Zn @ 0.5% foliar (35 DAS) improved Fe and Zn concentrations in rice significantly more than soil application of 25 mg Fe kg−1 and 5 mg Zn kg−1, respectively. The rice grain yield in clay soil was 14-42% higher than in sandy soil with different doses of Zn and Fe application. The order of preponderance of different Fe and Zn fractions were CA-Fe < OM-Fe < EX-Fe < FeMnOX-Fe < Res-Fe and Res-Zn > FeMnOX-Zn > OM-Zn > CA-Zn > Ex-Zn in the soils, respectively. Conclusively, concomitant consideration of grain yield and grain Zn and Fe concentrations of rice are the sustainable approach toward food targets achievement. [ABSTRACT FROM AUTHOR]

Soil moisture is one of the most important components in the land-air coupling system. Acquisition of soil relative moisture in high precision can benefit to the finer monitoring and assessment, as well as prediction and warning for drought and waterlogging. This study aims to assess drought and waterlogging using data fusion of soil water in multiple dimensions. Daily soil relative moisture was derived from China Meteorological Administration Land surface data assimilation system (CLDAS). Hourly soil relative moisture was observed from automatic soil moisture stations during April and November from the year of 2020 to 2023. The dataset also included the land use, soil properties and geographic information. A dynamic fusion model was constructed to correct the bias of relative soil moisture from between automatic soil moisture stations and CLDAS. Random forest and support vector machine models were used to take the latitude, longitude, altitude, soil sand, soil silt and soil clay as the inputs. Given that daily fusion relative soil moisture was constructed, the intensity, area and duration index were proposed to monitor and assess drought and waterlogging disasters at the multiple dimensions. The results showed that the values of determination coefficient between observed and corrected soil relative moisture by random forest model were 0.79, 0.81 and 0.80, respectively, and relative root mean square errors were 13.81%, 11.40% and 9.50%, respectively, at the length of 0-10, 0- 20 and 0-50 cm. Comparatively, the determination coefficient was 0.56-0.57 and relative root mean square error was 17.72%- 23.63% between observed and corrected relative soil moisture by support vector machine model. Thus, random forest model was accepted to effectively correct the bias of relative soil moisture between automatic soil moisture stations and CLDAS. Daily fused relative soil moisture was then generated as well. At the spatial scale, the days percent of water deficit increased from southeast to northwest in the period of April-November. Moreover, the days percent of water deficit in the central-western areas of Inner Mongolia and majority of Northwest China was greater than 70% and even 80%, while 50%-70% was found in northeastern Inner Mongolia, central-northern North China and central-western Southwest China, even less than 40% in major central-eastern areas. The days percent of soil overwetting decreased from southeast to northwest, with the value of greater than 50% only in eastern and southern South China, southern Southeast China and northeastern Northeast China. According to the water deficit index, overwetting, moisture, the area and duration index, drought and waterlogging conditions were dynamic assessed in the quantitative and finer characteristics at the intensity-area-duration dimension, especially in the typical disaster process, such as typical heat and drought event in Yangtze River in the year of 2022, typhoon Dusuri and Khanun in the year of 2023. Typically, the soil water deficit was tended to intensify in Yangtze River in the summer of 2022. The overwetting index was much lower during April-July in Huang-Huai-Hai region, whereas, there was the significant increase in late July by typhoon Dusuri, which was characterized by 12.3%-70.1% area exposed to waterlogging in 3-5 days. In Northeast China, the area exposed to overwetting or waterlogging in a large extent during 2-4th August in Heilongjiang and Jilin by typhoon Dusuri. After that, there was some decrease in 5-9th August, but it enlarged to 27.4%-41.8% in 10-13th August by typhoon Khanun. Of course, further investigation should be explored to consider more inducing factors on soil moisture. [ABSTRACT FROM AUTHOR]

In order to better understand the migration characteristics of ciprofloxacin (CIP) in specific types of soils, two soil samples with significant organic matter composition and physical and chemical properties potentially influenced by different geological and environmental backgrounds were selected from the groundwater irrigated farmland area of the North China Plain, and the adsorption-desorption mechanism of CIP in soil was studied kinetically and thermodynamically. The findings show that the kinetic experimental data are more in line with the quasi-second-order kinetic equation and the isothermal models are nonlinear, of which the Langmuir model turns out the best fitting. The parameters of adsorption kinetics constant (K2, 8 772.64 vs 2 846.37 g/(mg·h)), adsorption equilibrium rate constant (K1, 0.113 vs 0.094 L/mol) and maximum adsorption capacity (Qm, 5 033 vs 3 167 mg/kg) altogether exhibited higher values for Xianxian samples than those for the Zhengding, indicating faster adsorption rate and greater adsorption capacity of Xianxian soil. Correspondingly, the desorption rate (5.98% vs 8.07%), the maximum desorption amount (6 592 vs 7 564 mg/kg) and the adsorption free energy ΔG (-25.08 vs -23.00 kJ/mol) obtained from the desorption experiment consistently reflected that the soil in Xianxian County had better adsorption performance for CIP than the soil in Zhengding County. Based on the results of comprehensive experimental research and the analysis of spectral characteristics and physicochemical parameters, it is concluded that the high molecular weight, high aromaticity and multi-functional humus components of Xianxian soil and higher clay content are important factors for its overall better adsorption effect. The physical adsorption mechanism such as hydrophobic effect and electrostatic effect of humus molecules may play more active role in the adsorption of CIP antibiotics in Xianxian soil. [ABSTRACT FROM AUTHOR]

Hard soils-weak rocks combine characteristics of soil behavior and rock behavior. Perhaps the most distinct among them is brittleness reducing shear strength significantly after failure with very little additional shear displacement combined with intense dilation. Several hard soils-weak rocks were tested under drained direct shear conditions following consolidation to various vertical stress values. All of them exhibited very high reduction of shear strength after rupture, ranging from 32 to 71% taking place in as little as 0.1 mm of additional shear displacement. This loss of strength resulted in very large decrease of cohesion intercept and for all soils significant decrease in the angle of shearing resistance. Dilation was abrupt during rupture and was as high as 1.2 mm for the coarsest of the soils. Dilation was exhibited for all vertical stress values applied, never switching to contraction even for the highest vertical stress applied except one point for one soil. Percentage loss of peak shear strength after failure remained very high even for the highest vertical stress values applied, with points of percentage loss of peak strength with vertical stress falling in a very tight region for all soils. This is in clear difference to both the position of points falling on the same plot for a preconsolidated clayey soil and the higher rate of strength loss decrease with increasing vertical stress compared to the hard soils-weak rocks tested. The test results presented add to the existing understanding of the behavior of hard soils-weak rocks under drained direct shear and constitute examples of behavior of very brittle hard soils-weak rocks. [ABSTRACT FROM AUTHOR]

Black wattle is a tree native to Australia and commercially planted in South Africa and Brazil. Replacement of exported nutrients by wood and bark harvesting, associated with the maintenance of harvest residues, increases productivity, thus maintaining production sustainability. Here, we review recent advances in soil nutrient dynamics, harvest residue management (HRM), and soil organic matter in black wattle plantations. Over the 7–11-year cycle of black wattle, N is the most exported macronutrient (458–1509 kg ha− 1), followed by K (200–766 kg ha− 1), Ca (270–717 kg ha− 1), Mg (62–128 kg ha− 1), S (29–57 kg ha− 1) and P (16–40 kg ha− 1). The average increase in bark yield to 20 kg P ha− 1 applications on sandy soils was 2.7–2.9 t ha− 1 and on clay soils from 2.8 to 8.7 t ha− 1. Sandy soils with low K are more responsive to fertilizer, and rates must consider the K content and cation exchange capacity. Ca and Mg addition responses are more likely when in the topsoil they are in low concentrations (< 0.75 and 0.41 cmolc dm− 3, respectively). Micronutrient fertilization reduces the occurrence of gummosis caused by Phytophthora spp, and B deficiency is the most common and can be supplied by fertilization or foliar application (1 g B L− 1). Few studies have evaluated the impact of black wattle HRM on soil organic matter (SOM) and its effects on production. However, conserving SOM should be considered an essential practice for the sustainability of black wattle production. [ABSTRACT FROM AUTHOR]

Offshore floating systems are held in position with chains that connect the floater to anchors embedded in the seabed. An essential component for calculating the overall mooring capacity is an accurate assessment of the holding resistance from the anchor chains. Existing studies generally simplify the (complex) chain geometry to that of a cylindrical bar, which does not account for the intricate geometry of the connected chain links. This paper reports on three-dimensional finite-element modeling that defined the capacity of a link of anchor chain in clay soil with consideration of the geometry of the chain links, including the influence from adjacent links. Both stud link and studless links were considered, along with the effect of embedment depth, link direction angle, and interface condition. The soil resistance acting on the chain links, represented by uniaxial bearing capacity factors Nn,max , Ns,max , and Nt,max along the normal, lateral, and axial directions of the chain link, respectively, were derived, and the soil failure mechanisms for these conditions are discussed. Equivalent bearing capacity factors Nq and Na were derived by converting the soil resistance to normal and tangential resistances (q and f) acting on an equivalent cylindrical bar. Ultimately, f/q was calculated to represent the friction coefficient, μ , which ranged from 0.2 to 0.4. [ABSTRACT FROM AUTHOR]

AbstractDamping plays a crucial role in the design of offshore wind turbine (OWT) monopile foundations. The soil damping of the monopile-soil system (MSS) represents the energy dissipation mechanism arising from the interaction between the pile and the soil. It is typically derived by back-calculating from the overall damping measured in the entire OWT structure. However, few studies have independently examined the soil damping in MSS, and the impact of key parameters such as pile diameter, pile embedded depth, cyclic load amplitude, and load eccentricity on the variation of soil damping in MSS remains unclear. This paper introduces an elastoplastic-damage constitutive model for the numerical simulation of the damping ratio variation in seabed soil and MSS. The model is implemented in ABAQUS software and validated against cyclic triaxial tests on stiff clay soil. On this basis, a three-dimensional finite element sensitivity study was conducted to elucidate the effect of these key parameters on the MSS damping ratio. The results of the study reveal that the MSS damping ratio exhibits a nonlinear and asymmetric trend as the loading cycles increase. The MSS damping ratio decreases with increasing pile diameter and embedded depth but increases with increasing lateral cyclic load amplitude and load eccentricity from the mudline. [ABSTRACT FROM AUTHOR]

Geological hazards such as gully erosion, collapse and slope failure occur frequently in loess areas, which are closely related to the soil disintegration characteristics. Understanding the impact of freeze–thaw and wet–dry action on soil disintegration in the context of climate change is essential to establish effective soil and water conservation strategies and prevent engineering geological hazards in loess areas. In this study, sodic–saline loessial soils with different clay content were subjected to freeze–thaw and wet–dry cycles, followed by aggregate durability tests, direct shear tests and disintegration tests to investigate the effects of the two natural processes on soil disintegration characteristics. The results showed that the samples subjected to freeze–thaw cycles primarily exhibited rapid and stable disintegration, followed by slow disintegration, whereas the samples subjected to wet–dry cycles revealed weight gain, continuous slow disintegration and eventual sudden disintegration. Freeze–thaw action continuously deteriorated the disintegration resistance of soil, while wet–dry action improved the disintegration resistance of soil after the first cycle, and gradually weakened it in subsequent cycles. Statistical analysis showed that, for samples undergoing freeze–thaw cycles, the number of cycles and clay content were positively correlated with the disintegration rate, while the aggregate durability was negatively correlated with the disintegration rate. For samples undergoing wet–dry cycles, the number of cycles had a positive effect on the disintegration rate, while the clay content, shear strength and cohesion had a negative correlation with the disintegration rate. At a certain clay content, there was a positive correlation observed between the surface crack ratio, crack length and width with the disintegration rate of the wet–dry samples, while shear strength and cohesion had a negative correlation with the disintegration rate of both freeze–thaw and wet–dry samples. Furthermore, the study outlined the disintegration mechanism of loessial soils based on internal factors, driving factors, resistance factors and evolutionary factors. This study contributes to the in‐depth understanding of the catastrophic mechanism of geological hazards in cold and arid areas and provides experimental evidence for its control and management. [ABSTRACT FROM AUTHOR]

More exact information on soil nutrient management is crucial due to environmental protection, nature conservation, decreasing sources for mining, general precaution, etc. Soil magnesium (Mg) analytical methods of potassium chloride (KCl), Mehlich 3 (M3), water (WA) and cobalt hexamine (CoHex) extractions are compared with an elemental analysis and X-ray fluorescence (XRF) analysis. The ratio of the available to the total Mg content was calculated and compared on the whole dataset. The results showed that the linear regressions between all the pairs of Mg content measurement methods were significant. The linear relationship between the KCl and CoHex methods has the highest determination coefficient (R2 = 0.96), followed by WA–M3 (R2 = 0.68), M3–CoHex (R2 = 0.66) and M3–KCl (R2 = 0.60). The M3 solution demonstrated a greater capacity for extracting Mg from the soil. The second part is the analysis of the influence of CaCO3, pH, soil texture and clay content on the measurable magnesium content of soils. It was established that the extraction methods, the soil and the classification method of the soil properties affect the evaluation. These results may help through the nutrient replenishment and the melioration of soils. These results can help the examination of mineral nutrients, especially the Mg uptake. [ABSTRACT FROM AUTHOR]

Background and aims: The frequent occurrence of extreme rainfall events results in soils experiencing drying–rewetting (DRW) cycles. Such rewetting can lead to a surge in soil CO2 emissions; however, the main regulatory factors involved in this priming effect are unclear. Methods: In this study, we conducted a meta-analysis using data extracted from 43 published papers, to determine the direct regulatory factors involved in the priming effect of soil CO2. Results: The results indicated that the priming effect of rewetting on soil CO2 emissions was influenced by ecosystem type, soil properties, climatic factors, and the number of DRW cycles. The priming effect was the highest in cropland but the lowest in grassland when taking flux values observed before rewetting as the control group. It was also greater in acidic soils (pH < 6.5) and soils with a high clay fraction (clay ≥ 30%) than in other soils. The effect size (lnRR) of soil CO2 emissions was exponentially related to the mean annual precipitation (MAP), and decreased with increases in MAP. In DRW experiments, the priming effect of the first rewetting on soil CO2 emissions was the largest, an effect that gradually decreased with the number of DRW cycles, before disappearing completely. Most importantly, soil moisture influenced the peak time and the pulse time of the priming effect: the greater the change in soil moisture, the longer the peak time duration; the higher the maximum soil moisture content after rewetting, the longer the pulse time duration; and the lower the initial soil moisture content, the bigger the priming effect. Conclusion: Generally, physical mechanisms, especially soil moisture, directly regulate the CO2 priming effect during DRW cycles. Thus, this study provides a theoretical basis for assessing and predicting the impact of future precipitation changes on soil carbon cycling. Future studies should also carefully monitor any changes in soil microorganisms in response to changes in soil moisture during DRW cycles, because these appear to be significantly involved in CO2 release from soils. [ABSTRACT FROM AUTHOR]

Soil-improvement techniques with binders are used in several geotechnical engineering applications as a sustainable solution for the reuse of waste soils. Due to their inherent complexity and their mechanical behaviour, pyroclastic soils are generally considered waste geomaterials in their natural state. Lime treatment of pyroclastic soils can be considered a viable solution for their reuse in geotechnical applications. In this paper, some peculiar features of the chemo-physical evolution and mechanical behaviour of lime-treated pyroclastic soils are evidenced through a multi-scale experimental investigation. While, for clayey soils, the fine fraction is mainly responsible for ion exchange and pozzolanic reactions induced by lime, for pyroclastic soils, pozzolanic reactions are dominant processes due to the low quantity of clay minerals along with the abundance of aluminates and silicates as the main constituents of their amorphous phase. The link between the phenomena detected at the microscale level, the mineralogical composition, and the macroscopic behaviour of two lime treated pyroclastic soils of different origin is explored through a multiscale approach. [ABSTRACT FROM AUTHOR]

CPR grouting is a technique used to improve soft clayey soils through vertical drains and the injection of low mobility grout. CPR grouting still faces limited acceptance among certain practitioners, primarily due to the doubtful process of soil consolidation induced by grout injections. The aim of this study is to investigate the behavior of soft clays subjected to CPR grouting, attempting to enhance the theoretical understanding of the technique and evaluating the related consolidation process. The technique is studied using a special laboratory apparatus, in which a latex membrane is inflated within a soil specimen to simulate the grout injection. In this paper, we introduce the modified equipment, its components, describe the experimental procedure, outline the sample preparation, and present the experimental results. The key findings of this study suggest that injection pressure appears to be unrelated to the expanded volume, the peak injection pressure is similar across all tests, and larger injected volumes does not necessarily produce higher amount of soil consolidation. Although laboratory conditions are not identical to field conditions, laboratory tests indicate that grout injection does lead to consolidation in the soft clay, offering a valuable empirical guidance for a more cost-effective grouting design plan. [ABSTRACT FROM AUTHOR]

Soil is a natural heterogeneous material and from its formation process, heat transfer capacity (thermal conductivity) of soil is playing vital role in many engineering applications. The aim of this research study is to enhance thermal conductivity using natural and treated bacteria from soil samples procured from four different regions namely Dholera, Navsari, Sabarmati River, and Madhavpur of Gujarat, India. To fulfill this objective, thermal conductivity test set‐up was indigenously developed based on guarded hot plate method and is calibrated up to 150°C temperature. The colonies of microorganisms available in soil were studied by serial dilution and spread plate technique. Further, influence of microorganisms on soil structure aggregation pre and post treatment was analyzed by microscope. Four types of microorganisms were introduced in the soil and the thermal conductivity of sample is measured for curing period of 7, 14, 21, and 28 days. The results indicate increment in k value for thermal conductivity in clayey soil up to 26.67% and decrement in sandy soil is up to 45.45%, while most optimum results were observed for 7 days curing period. Present research demonstrates use of microbes available in various soils to enhance heat transfer mechanism through proper identification and treatment. [ABSTRACT FROM AUTHOR]

The significant challenges facing geotechnical engineers concerning gypseous soils and their behavior under water flow require careful assessment of gypsum soil performance under wet conditions. Improving gypsum soils through the inclusion of enhanced additives is among the most widely employed methods. The major objective of the current study was to investigate the effect of fiber additives on the engineering properties of gypseous soils experimentally. Natural fiber has been mixed into sandy and clay soils in several studies, but gypseous soils have not been investigated. However, the study investigated the properties of gypseous soils with three gypsum content (19%, 36%, 62%) improved by an agricultural waste of sugarcane bagasse (SCF) used as natural fiber and polypropylene (PPF) as an industrial fiber, these materials are economic, renewable and eco-friendly. The effect of fibers on compaction characteristics, specific gravity, and shear strength parameters at both dry and soaked conditions (soaked in water for 1 day) is investigated. Fibers used by percentage (0- 0.8% by weight of dried soil). From the result of soil improved by polypropylene fibers (PPF), The significant increase was observed in cohesion under both dry and soaked conditions, surpassing the cohesion increment observed in soil treated with SCF. in dry conditions for soil treated by (PPF) the increment was recorded (20%-126%), and for soil treated by (SCF), the increment was recorded (19%-81%). But the angle of internal friction of the soil improved by SCF in dry and soaked conditions was higher than that soil treated by PPF, in dry condition for soil treated by PPF the increment was recorded (8%-33%) and (21%-54%) for soil treated by SCF. shear strength parameters in the dry condition are more than the increment in soaked condition for treated soil by (PPF and SCF), also from the results can be obtained the optimum fiber content was 0.6%, and 0.4% for SCF and PPF respectively. The max. dry unit weight and specific gravity for three types of soils decreased by increasing fiber content but optimum moisture content increased by increasing fiber content. Lastly can be concluded the PPF gave better results than SCF. [ABSTRACT FROM AUTHOR]

We have studied soils of the western coast of the Chivyrkui and Barguzin bays on the Svyatoi Nos Peninsula, which is the largest peninsula of Lake Baikal in the Republic of Buryatia. Morphogenetic characteristics of soils on the main types of coasts of the peninsula—low abrasion with isolated lagoons, low abrasion, accumulative, and ingression—are given. Rocks in the basis of the coasts of the bays are an important factor of soil formation. It is shown that the genesis of soils depends on the distance from the lake and the altitude, resulting in the difference in their structure and properties. The soils are not directly affected and flooded by lake water due to high mountainous coasts, which are often rocky with steep slopes. Soil formation beyond the floodplain regime is also typical for soils of the closest to the lake level: soddy podzols, which occupy low shores of accumulative types. The particle-size composition of the studied soils varies widely from loose sand to light clay. The common properties of soils include acid and weakly acid reaction, the regressive-accumulative type of humus distribution, and differentiation of bulk oxides along the profile. The revealed evidences of podzolization in Al–Fe-humus soils and of clay accumulation in brown soils are related to sufficient moistening of the coasts and the warming effect of the lake water mass. The research results may be used in landscape planning in territorial organization and monitoring work in recreation areas. [ABSTRACT FROM AUTHOR]

The unreasonable use of fertilizers is a significant cause of cultivated soil cadmium (Cd) accumulation. Although there is research about the effect of fertilizers on soil cadmium (Cd) accumulation under different crops, soils, and cultivation durations locally and specifically, its relative and determinant factors are seldom comprehensively and comparatively researched and evaluated. We used meta-analysis to analyze the effects of fertilizers (mineral fertilizer N, P, K (NPK) with manure (NPKM), NPK with straw (NPKS), and the mineral fertilizer N (N), NK (NK)), crops, duration, climate, and soil texture on the Chinese soil total and available Cd change during 1987–2022. The results showed that the order of the increased soil total and available Cd change was NPKM (total: 62%–104%, available: 61%–143%) > NPKS (50%–86%, 48%–116%) > NPK (25%–50%, 35%–75%) > NK (5%–19%, 19%–33%) > N (2%–6%, 7%–31%). NPKM and NPKS significantly increased the total Cd under maize (104%, 86%) and available Cd under rice (136%, 116%). Cd changed the fastest with the NPKM cultivation duration for total Cd under maize (slope: 5.9) and available Cd under rice (6.6). The change of the soil total and available Cd had the higher value in the semiarid region, clay soils, lower pH, and long cultivations. The change of the soil total and available Cd were highest (398%, 375%) in the semiarid region for clay loam after 20–25 years of NPKM fertilization, when the pH decreased to the lowest (−1.9). According to the aggregated boosted tree analysis, the fertilizers and duration were the best explanatory variable (>53%) for the soil total and available Cd. In conclusion, the soil Cd could be mitigated through reducing the long–term manure, straw, and P fertilizer content with Cd, and field managements such as liming, wetting, and drying according to the crops, climate, and soil texture. [ABSTRACT FROM AUTHOR]

Granite residual soil is a widely encountered clayey soil with unique microscopic soil structures. Its soil structures mainly stem from the presence of interparticle cementation by iron oxide. An attempt is made herein to experimentally quantify the impact of interparticle iron oxide cementation on soil's mechanical properties, particularly in the high suction range. The amount of interparticle cementation is artificially generated by mixing soil samples with varying mass fractions of iron hydroxide colloid. The mechanical behavior of these soil samples in the full suction range is measured via the drying cake test. Preliminary experimental results demonstrate that interparticle iron oxide cementation can significantly decrease soil shrinkage (by up to 52%), and substantially increase soil elastic modulus (by up to 1.83 times) and negative suction stress change (by up to 0.82 times). [ABSTRACT FROM AUTHOR]

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

Laboratory experiments on clayey soils under dynamic triaxial compression were conducted to establish a nonlinear relationship between the dynamic modulus of soil deformation and the frequency of impact. The most significant increase in the dynamic modulus of soil deformation is observed under an increase in frequency from 5 to 10 Hz. In comparison with fluvioglacial soils, the dynamic deformation modulus in glacial loams grows slower under an increase in frequency. This confirms the dependence of the obtained relations on the genesis of soils. The research results were used to develop vibration protection systems for high-precision equipment in high-tech industries. [ABSTRACT FROM AUTHOR]

Climatic wetting‐drying cycles exacerbated by climate change can trigger several weakening mechanisms in surface soils, potentially leading to instability and failure of slopes and earthen structures. This study proposes a bio‐mediated approach based on microbially induced calcite precipitation (MICP) to increase soil resilience to wetting‐drying cycles. To explore its viability and the underlying mechanisms, we conducted a series of laboratory tests on clayey soil that underwent six wetting‐drying cycles. The tests were conducted with different treatment methods to investigate the effect of treatment sequence and cementation solution concentration. After MICP treatment, the initial evaporation rate, surface crack ratio during drying, and total soil weight loss during rainfall erosion were reduced by up to 32%, 85%, and 90%, respectively. Spraying the cementation solution first in the MICP treatment sequence proves more effective in improving soil water retention capacity. On the other hand, initiating the sequence with the bacterial solution demonstrates a more pronounced effect in reducing soil desiccation cracks and erosion. Microstructure analysis reveals that the content and distribution of CaCO3 precipitation are the major factors controlling the effectiveness of MICP for the cementation of clayey soil. Employing MICP can minimize the carbon footprint and contribute to developing environmentally friendly solutions for soil improvement in regions affected by climatic wetting‐drying cycles. Plain Language Summary: The rising frequency and intensity of climatic wetting‐drying cycles driven by climate change pose a threat to surface soil stability, consequently increasing the risk of land degradation, soil erosion, landslide, and other forms of ground instabilities and failures. This study presents a bio‐mediated approach using microbially induced calcite precipitation to enhance soil resilience to wetting‐drying cycles. Experimental results show that MICP is capable of improving soil properties related to water retention, desiccation resistance, and erosion control. The microstructure analysis further elucidates the role of MICP‐induced CaCO3 precipitation in cementing clayey soil and demonstrates that the bio‐created buffer barrier significantly mitigates the adverse effect of climatic wetting‐drying cycles on surface soil. This study is expected to offer an environmentally friendly and sustainable soil improvement solution in regions impacted by cascading climatic extremes. Key Points: A sustainable bio‐mediated approach using microbially induced calcite precipitation (MICP) was applied to enhance soil resilience to climatic wetting‐drying cyclesMICP significantly improves water retention, desiccation and erosion resistance of surface soilThis study provides new insights into the fundamental mechanisms of the interaction between climate and MICP‐treated soil [ABSTRACT FROM AUTHOR]

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

The study investigated the adsorption of dissolved organic carbon (DOC) on Chinese soils from four long-term experiments involving five treatments: (1) no fertilization (control), (2–4) inorganic nitrogen (N), phosphorus (P), and potassium (K) fertilization (N, NP, and NPK), (5) NPK plus manure (NPKM). The results showed that DOC adsorption followed a modified Langmuir isotherm model effectively (R2 = 0.912 ~ 0.991). The maximum adsorption capacity (Qmax) (i.e. saturation deficits) generally increased with increasing soil organic carbon (SOC) due to fertilization in Luvic Phaeozem, Haplic Gypsisols, and Eutric Cambisols. However, it decreased significantly in acidic soils (Haplic Acrisols) from 15.59 g/kg for control, to 13.96, 13.03, 9.30 and 8.02 g/kg for N, NP, NPK and NPKM, respectively. Moreover, long-term fertilization, particularly with organic fertilization (e.g. NPKM), resulted in an increase of carbon (C) saturation by 1.42 g/kg (5.52%) in Luvic Phaeozem, 9.27 g/kg (44.29%) in Haplic Gypsisols, and 3.75 g/kg (27.66%) in Eutric Cambisols; however, there was a slight decrease by 1.70 g/kg (−7.49%) in Haplic Acrisols. Canonical correlation analysis (CCA) revealed that clay content and soil available iron (AFe) might be the crucial factors controlling C deficits, and subsequently, C saturation, along with current SOC. In conclusion, long-term fertilization contributed to C saturation in neutral-to-alkaline soils, but not in acidic soils. Thus, further attention should be paid to the long-term effects of fertilization on C saturation. [ABSTRACT FROM AUTHOR]

The paper presents the results of systematic investigations on the gamma dose rates in air, natural radioactivity in soil and the dependence of radioactivity on the mineralogy of soils in the environs of the Belagavi, Karnataka, India. The gamma dose rates were measured using a portable survey metre and the activity in soils were measured using NaI(Tl) based gamma ray spectrometer and the mineral composition was studied using FTIR spectroscopy. The activity of 40K varies from 72.52 to 324.76 Bq kg−1 with an average of 153.17 Bq kg−1. The 226Ra activity varies from 16.53 to 70.53 Bq kg−1 with an average value of 23.88 Bq kg−1 and the activity of 232Th varies from 10.95 to 59.07 Bq kg−1 with an average value of 25.75 Bq kg−1. Elevated levels of 226Ra, 232Th and 40K in soils were observed in some part of Belagavi, which was traced to the mineralogy of the region. The higher activity of natural radionuclides poses radiological implications to the population of the region. The activity utilisation index was found to be is above the normal levels in some locations. The pattern of distribution of radionuclides in the region was studied using SPSS statistical software. The soil with clay minerals Haematite, Calcite, Kalonite, Albite and Feldspar showed higher radionuclide content. [ABSTRACT FROM AUTHOR]

Soil pressure in clay formation tunnels is closely related to soil arch effect and the development of slip surfaces. Firstly, numerical simulation software is used to simulate the actual situation of tunnel excavation, and the change rule of the slip-cracking surface of cohesive soil is analyzed. Secondly, based on the numerical simulation results and the ellipsoid theory, the pressure formula of Terzaghi loose Earth is modified considering that the principal stress trace is catenary. Finally, the calculation results are compared with the finite element calculation results to verify the rationality of the formula in this paper. The relationship between the internal friction angle, cohesion force c, eccentricity ε, looseness coefficient β, and the pressure of loose Earth is further studied. The results show that there is a gap between the sliding crack angles with or without dilatancy angle and it will affect the development form of soil arch. The slip angle decreases gradually with the increase of the buried depth ratio H/D and becomes stable when the buried depth ratio H/D≥3. Compared with deep-buried tunnels, the increase of internal friction angle in the shallow-buried tunnel is more conducive to reducing the overlying soil pressure. The loose soil pressure decreases with the increase of eccentricity ε and loose coefficient β, and the influence of eccentricity ε on loose soil pressure is significantly greater than that of loose coefficient β. Therefore, the change of eccentricity ε should be paid close attention in the project. [ABSTRACT FROM AUTHOR]

Bottom-initiated radial cracking is a special phenomenon for soil as it is subjected to desiccation. This study aims to simulate the initiation and propagation of radial cracks in soil using both experimental and discrete-element method (DEM) approaches. Under controlled conditions of constant temperature and humidity, a laboratory desiccation test of clayey soil samples with bottom-constrained boundary conditions was carried out to illustrate the soil bottom-initiated radial desiccation cracking behavior. The evaporation characteristics as well as the development of radial cracking initiating from the subsoil were captured. To simulate this phenomenon, a desiccation model based on discrete-element method was used in DEM. Based on the laboratory testing results, appropriate parameters are selected for the numerical simulations. The DEM approach was calibrated by reproducing the experimental results of radial desiccation cracking. Subsequently, the initiation and propagation mechanisms of this typical soil cracking phenomenon was analyzed and discussed. With the constraint of the bottom boundary, the initiation of radial desiccation cracking was associated with the arched distribution of inter-particle tensile force in the soil samples. The propagation direction of the cracks was perpendicular to the inter-particle tensile forces. Finally, the effects of basal friction, evaporation gradient and shrinkage parameter on the bottom-initiated radial cracks in the simulation were analyzed. The size of the bottom particles and interface bonding factor played a significant role in the effect of basal friction. Compared with the samples under uniform water loss conditions, the bottom shrinkage rate was relatively low for the sample under a gradient water loss. In addition, an increase in the shrinkage parameter of the soil particles led to a greater extent of crack propagation. [ABSTRACT FROM AUTHOR]

The present study has focused on stabilizing the soils of the embankments and improving the mechanical properties of gravel in subbases of pavements with different contents of bottom ash from thermal power plants and low percentages of lime. The density, humidity, simple resistance strength and bearing capacity of the new materials resulting from this combination have been studied. The results indicated that the optimal proportion of bottom ash added to the analyzed soil is 15%, while the optimal addition of lime is 1% for application in embankments and 2% for application in road subgrades. In clay soil that has a low simple resistance strength when 25% of bottom ash is added without lime, it can double the resistance. In the case of the gravel evaluated, it was found that the optimal ratio between the addition of bottom ash and lime is 6.5. In conclusion, it can be noted that soil that does not have any resistance when certain percentages of bottom ash are added, its properties are improved to be used in embankments. [ABSTRACT FROM AUTHOR]

Understanding the efficacy of alternative phosphorus (P) sources in tropical soils is crucial for sustainable farming, addressing resource constraints, mitigating environmental impact, improving crop productivity, and optimizing soil-specific solutions. While the topic holds great importance, current literature falls short in providing thorough, region-specific studies on the effectiveness of alternative P sources in Brazilian tropical soils for maize cultivation. Our aim was to assess the agronomic efficiency of alternative P sources concerning maize crop (Zea mays L.) attributes, including height, shoot dry weight, stem diameter, and nutrient accumulation, across five Brazilian tropical soils. In greenhouse conditions, we carried out a randomized complete block design, investigating two factors (soil type and P sources), evaluating five tropical soils with varying clay contents and three alternative sources of P, as well as a commercial source and a control group. We evaluated maize crop attributes such as height, dry weight biomass, and nutrient accumulation, P availability and agronomic efficiency. Our results showed that, although triple superphosphate (TSP) exhibited greater values than alternative P sources (precipitated phosphorus 1, precipitated phosphorus 2 and reactive phosphate) for maize crop attributes (e.g., height, stem diameter, shoot dry weight and phosphorus, nitrogen, sulfur, calcium and magnesium accumulation). For instance, PP1 source increased nutrient accumulation for phosphorus (P), nitrogen (N), and sulfur (S) by 37.05% and 75.98% (P), 34.39% and 72.07% (N), and 41.94% and 72.69% (S) in comparison to PP2 and RP, respectively. Additionally, PP1 substantially increased P availability in soils with high clay contents 15 days after planting (DAP), showing increases of 61.90%, 99.04%, and 38.09% greater than PP2, RP, and TSP. For Ca and Mg accumulation, the highest values were found in the COxisol2 soil when PP2 was applied, Ca = 44.31% and 69.48%; and Mg = 46.23 and 75.79%, greater than PP1 and RP, respectively. Finally, the highest values for relative agronomic efficiency were observed in COxisol2 when PP1 was applied. The precipitated phosphate sources (PP1 and PP2) exhibited a similar behavior to that of the commercial source (TSP), suggesting their potential use to reduce reliance on TSP fertilization, especially in soils with low clay contents. This study emphasized strategies for soil P management, aimed at assisting farmers in enhancing maize crop productivity while simultaneously addressing the effectiveness of alternative P sources of reduced costs. [ABSTRACT FROM AUTHOR]

Mineralogical and geotechnical properties used to analyse the swelling potentials of Al-Hartha City. According to mineralogy, montmorillonite is a dominated clay mineral (33.61%) followed by montmorillonite-chlorite (33.34%), kaolinite (9.18%) and illite (5.38%). While calcite, Quartz, Feldspar, and dolomite are non-clay minerals that are also present. According to geotechnical analysis, the percent of clay range between 9-42% with an average of 25.5%, silt 55-80% with an average of 67.5% and sand 0-17% with an average of 8.5%. While liquid limits and plasticity index are, respectively, 10–25% with an average of 17.5% and 35%–51% with an average of 43%. According to the unified soil classification system (USCS), these soils are mainly low plasticity lean clay soils (CL) and 10% classified as medium stiff elastic silt (MH). According to activity values, soils are primarily inactive-(70%), normally active-(20%), active-(10%), and their consistency is plastic. according to an assessment of soil expansivity based on index properties and activity, a significant amount of the soil is expansive. Additionally, there is an agreement between the results of the mineralogical tests performed on these soils and the results of the measures of soil expansivity obtained from the evaluation of the swelling of the soil based on assessments of its index properties. [ABSTRACT FROM AUTHOR]

Purpose: The use of sewage sludge associated with natural rock-based fertilizers can increase nutrient solubility and soil fertility. From this perspective, this study evaluated changes in the chemical soil attributes and the nutrient availability rate after the application of sewage sludge, natural phosphate, and elemental sulfur in soils with different clay contents. Method: The study was conducted in a controlled environment and was set up in a completely randomized design with four replications in a 3 x 5 x 5 factorial arrangement consisting of soil with three clay contents: 28%, 34%, and 42%; five fertilization managements: unfertilized (Control), fertilized with natural phosphate (NF), fertilized with sewage sludge (SS), fertilized with natural phosphate and elemental sulfur (NF+S), and fertilized with NF+S+SS; and five evaluation times: 0, 30, 60, 90, and 120 days after fertilization. The chemical soil attributes and the nutrient availability rate were evaluated. Results: The application of sludge, natural phosphate, and sulfur increased the contents of SOM, N, P, K, Ca, Mg, Al, H + Al, SB, and CEC and reduced the soil pH, in addition to favoring the rate and time of availability of P, Ca, and Mg, with means higher than 50% in the soils from 30 to 120 days after application. At 120 days after application of sludge, the average availability rate of P, K, Ca, and Mg corresponded to 37, 13, 144, and 157%, respectively. Conclusion:These improvements imply savings with mineral fertilizers and contribute to adopting conservationist and sustainable practices. The individual application of sewage sludge or its application with natural phosphate and elemental sulfur increased soil fertility and the nutrient availability rate in soils with different clay contents. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this research was to examine the influence of olive kernel biochar on silty clay soil that is susceptible to erosion. The hypothesis proposed that the effectiveness of biochar in improving soil physical properties and mitigating soil erosion depends on factors such as application rate, particle size as well as placement method. Materials and methods: Three application rates (0, 1, and 2%) and two particle size ranges (53–250 and 250–500 µm) of biochar were tested, along with two placement methods (commixing and slurry). Effects of biochar application on soil aggregate stability and water repellency were investigated after a 10-month incubation period. Effectiveness of biochar to reduce soil loss and runoff generation was also assessed. Results and discussion: The biochar application resulted in a reduction of soil water repellency. Notably, regarding particle size, application rate, and placement method, no statistically significant difference was observed. The slurry method resulted in about 30% higher mean weight diameter of aggregate (MWD) compared to the commixing. The reduced soil disturbance in the slurry method may allow for greater enhancement of soil aggregation by biochar. The relative decrease in runoff (462 vs. 356%) and soil loss (52 vs. 23%) in biochar-treated soils compared to the control treatment were considerably higher in the slurry than commix method. The results also demonstrated a significant interaction between the biochar placement method and treatment type regarding soil loss characteristics in both commixing and slurry methods. Larger biochar particles at higher rates effectively reduced runoff and soil loss using the slurry method, while smaller biochar particles at lower rates were more effective with commixing method. Conclusion: Overall, the slurry method proved effective in incorporating biochar into erosion-prone areas. Furthermore, the selection of appropriate biochar particle sizes and application rates is crucial for optimizing desired outcomes. [ABSTRACT FROM AUTHOR]

Clayey soils exhibit significant volumetric changes in response to variations in water content. The swelling pressure of clayey soils is a critical parameter for evaluating the stability and performance of structures built on them, facilitating the development of appropriate design methodologies and mitigation strategies to ensure their long-term integrity and safety. We present a dataset comprising maximum swelling pressure values from 759 compacted soil samples, compiled from 16 articles published between 1994 and 2022. The dataset is classified into two main groups: 463 samples of natural clays and 296 samples of bentonite and bentonite mixtures, providing data on various types of soils and their properties. Different swelling test methods, including zero swelling, swell consolidation, restrained swell, double oedometer, free swelling, constant volume oedometer, UPC isochoric cell, isochoric oedometer and consolidometer, were employed to measure the maximum swelling pressure. The comprehensive nature of the dataset enhances its applicability for geotechnical projects. The dataset is a valuable resource for understanding the complex interactions between soil properties and swelling behavior, contributing to advancements in soil mechanics and geotechnical engineering. [ABSTRACT FROM AUTHOR]

Chloramphenicol, a broad-spectrum antibiotic employed for controlling bacterial infections, presents an intriguing aspect in terms of its environmental fate in soils. 14C-labeled chloramphenicol was used to explore its mineralization and residue characteristics in three distinct agricultural soils in China. The findings revealed a nuanced pattern in the fate of 14C-chloramphenicol, with notable variations among the different soils under investigation. The chloramphenicol extract residue exhibited a reduction of 18.04% in sandy clay soil, 23.04% in clay loam soil, and 21.73% in loamy clay soil. Notably, the mineralization rate in sandy clay soil was 25.22% surpassed that in the other two soils, particularly during the initial stages of incubation. Over time, the diminishing extract residue underwent conversion into minerals and bound residue. The formation rate of bound residue was increased from 44.59 to 53.65% after adding 10% manure, suggesting that chloramphenicol easily binds with soils rich in organic matter. The bound residue is predominantly localized in the humin fraction across all soils. Additionally, the sterilized soil experiments indicated the pivotal role of microorganisms in influencing the fate of chloramphenicol under the specified experimental conditions. In conclusion, this study offers valuable insights into the environmental dynamics of chloramphenicol in soils, emphasizing the importance of soil composition, organic matter content, and microbial activity. The findings contribute to a scientific understanding of the environmental safety implications associated with chloramphenicol usage. [ABSTRACT FROM AUTHOR]

Aims: We aimed to understand how eucalypt forests planted in highly weathered natural low fertile soils of the Brazilian Cerrado would benefit from the use of limestone (+ L) and phosphogypsum (+ G) applied banded or broadcast and incorporated or non-incorporated. Methods: The treatments applied here can be grouped into three, as follows: Group 1 – consists of three treatments that did not receive any limestone or phosphogypsum (control); Group 2 – consists of four treatments with + L only (different ways of applying + L); and Group 3 – consisting of two treatments including + L + G combined (different ways of applying + L + G). Results: The + L banded (Ba) and incorporated (I) (+ LBaI – Group 2) provided the greatest residual effect on soil chemical characteristics, increasing Ca2+ and Mg2+ availability and decreasing exchangeable and active acidity, regardless of the soil type. Consequently, an increase of 39.4% (~ 91.4 m3 ha−1) and 16.7% (~ 47 m3 ha−1) of eucalypt wood volume was obtained in the sandy and clay soils, respectively, when compared to the controls. However, when + L and + G were combined (Group 3) it increased S-SO42− concentrations, improving root development in the deeper layers. This resulted in the highest eucalypt productions with 58% (122.7 m3 ha−1) and 29% (94.7 m3 ha−1) more wood than the control in the sandy and clay soils, respectively. Conclusions: The application of + L and + G increased wood production of eucalypt planted forests in highly weathered and low fertile tropical soils due to better plant nutrition and soil amelioration. [ABSTRACT FROM AUTHOR]

Soil properties are crucial in forest ecological management and rare vegetation protection. In this study, Fanjing Mountain, a typical subtropical forest, was used to investigate and analyze the differences in soil properties and climate change characteristics of Fanjing Mountain in 1982 and 2014. Then redundancy analysis was used to analyze the influence of climate factors on soil properties. The results showed that: 1) Compared to 1982, the soil properties of Fanjian Mountain changed significantly in 2014. The soil texture evolved from a silty loam in 1982 to a silty clay loam in 2014. There was a significant increase in soil clay particles. In addition, the soil showed acidification, weakened cation exchange capacity, and relatively stable soil total nitrogen but significant loss of soil organic matter and total phosphorus nutrients. 2) In the past 32 years, the environmental climate of Fanjing Mountain has shown the characteristics of increasing annual average temperature and annual rainfall, frequent extreme temperature, widening the annual temperature range and decreasing annual relative humidity. 3) Soil type and maximum annual temperature have a highly significant effect on the evolution of soil properties, while annual rainfall and slope orientation significantly affect the evolution. Conclusion: The evolution of soil properties in subtropical forests is dominated by their type differences and climate warming. [ABSTRACT FROM AUTHOR]

Inorganic arsenic (iAs) is a carcinogen. Vegetables such as water spinach (Ipomoea aquatica Forssk.) and amaranth (Amaranthus mangostanus L.) are recognized as high-risk sources of iAs exposure because they can accumulate significant amounts of iAs and are widely consumed. To ensure safe cultivation conditions, this study aimed to establish prediction models for iAs concentration in the edible parts of water spinach and amaranth based on soil properties. Subsequently, health risk assessments associated with iAs exposure through the consumption of these vegetables were conducted using prediction models. Soil samples were collected from agricultural fields in Taiwan and used in the pot experiments. Pearson correlation and partial correlation analyses were used to explore the relationship between soil properties, including total As, clay, organic matter, iron oxides and available phosphates, and iAs concentration in edible parts of water spinach and amaranth. Prediction models based on soil properties were developed by stepwise multiple linear regression. Health risk assessments were conducted using the Monte Carlo algorithm. The results indicate that total As and organic matter contents in soil were major predictors of iAs concentration in water spinach, whereas those in amaranth were total As and clay contents. Therefore, higher health risks for consuming water spinach and amaranth are associated with higher levels of organic matter and clay contents in soil, respectively, and these are crucial factors to consider to ensure food safety. This study suggested that As-elevated soils enriched with organic matter and clay contents should be avoided when growing water spinach and amaranth, respectively. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) are key members of soil microbial communities and play a key role in regulating ecosystem processes. However, the mutual interdependence of plants and AMF in threatened Miombo woodlands has not yet been fully elucidated. In this study, we investigated the relationship between plant ecological indicators and soil mycorrhizal inoculum potential (MIP) in the Miombo forest fallow of Haut‐Katanga, Democratic Republic of Congo, and identified plant species that positively influence soil MIP. We conducted a floristic inventory on 32 plots and collected soil cores for physicochemical and AMF characterization. Trap cultures using Crotalaria juncea seedlings were performed to determine the soil MIP. We also tested the AMF colonization status of randomly collected living roots of mature woody and dominant herbaceous species to identify explanatory variables for MIP. Our results showed that MIP was twice as high in silty clay soils (63.13%) than in clay soils (30%). Furthermore, MIP increased accordingly with the relative abundance of a group of woody and herbaceous species (e.g., Albizia adianthifolia, Baphia bequaertii, and Setaria pumila) and decreased with others (e.g., Combretum collinum, Harungana madagascariensis and Hyparrhenia diplandra). Linear regressions showed that MIP increased significantly with the specific richness of woody species identified as indicators and with the amount of annual herbs. Woody legumes with high root colonization by AMF appeared to be refuge plants, and primary AMF dispersal vectors, increasing soil MIP. This study provides baseline data that can be used to formulate ecological restoration strategies, including soil and vegetation protection. [ABSTRACT FROM AUTHOR]

This research addresses the characteristics of soft soil subgrades treated by soilbags filled with excavated clayey soil. We evaluated of the strength and deformation modulus of soilbags containing excavated soil using unconfined compression tests. In addition, the drainage consolidation characteristics of soilbag-treated subgrades were investigated via model consolidation tests. Furthermore, a practical application included the construction of a 100 m-long rural road subgrade with these soilbags. The field test and numerical simulation results included the surface settlement and pore water pressure during and after construction to validate the effectiveness of the soilbag treatment for soft soil subgrade. The results show that the soilbags significantly enhanced both the strength and deformation modulus of the soft soil, which met the design requirements after the soilbag treatment. The drainage attributes of the soilbag treatment were also found to support the consolidation process of the soft soil subgrade effectively. Notably, the pore water pressure diminished rapidly during the construction interval, which is beneficial to reducing the post-construction settlement. The settlement uniformity of the subgrade is good verification of the superiority of the soilbag-treated subgrades. [ABSTRACT FROM AUTHOR]

Pore-size distribution (PSD) of soil is a fundamental property that determines flows of water, heat, chemicals, and electricity and controls distributions of stress and deformation. PSD can be intrinsically related to the soil–water retention curve (SWRC), which is a constitutive relationship describing how the soil skeleton retains pore water via adsorption and capillarity. A general framework to quantify soil's PSD is proposed by first fitting an analytical SWRC model to experimental water retention curves that explicitly separate the SWRC into an adsorptive SWRC and a capillary SWRC. The PSD is then estimated at incremental steps by combining the capillary SWRC and the conventional Young–Laplace equation relating capillary pressure to pore size. Cumulative and density PSD curves for 11 soils covering a wide spectrum of soil types are determined and compared with the PSD functions independently measured using mercury intrusion porosimetry (MIP). Good agreement is observed in the estimated pore size range, distribution pattern, and peak position determined from the two different methods. Differences observed in the methods are attributed to differences inherent in the use of wetting and nonwetting fluids to probe the pore space. The SWRC-based method generally characterizes pore sizes ranging from 100 to 0.02 μm with a major peak located within a pore diameter range of 1–10 μm. As the clay content increases, a secondary peak becomes evident at smaller pore sizes (about 0.01–0.1 μm), where the bimodal pattern reflects the dual-porosity microstructure commonly observed for clayey soils. For soils containing swelling clays, PSD can change substantially with variation in water content; thus, the water-based method is more appropriate than MIP for applications to geotechnical engineering practice. [ABSTRACT FROM AUTHOR]

Saltmarshes are known for their ability to act as effective sinks of organic carbon (OC) and their protection and restoration could potentially slow down the pace of global warming. However, regional estimates of saltmarsh OC storage are often missing, including for the Nordic region. To address this knowledge gap, we assessed OC storage and accumulation rates in 17 saltmarshes distributed along the Danish coasts and investigated the main drivers of soil OC storage. Danish saltmarshes store a median of 10 kg OC m−2 (interquartile range, IQR: 13.5–7.6) in the top meter and sequester 31.5 g OC m−2 yr−1 (IQR: 41.6–15.7). In a global context, these values are comparatively low. Soils with abundant clay (> 20%), older and stable saltmarshes in mesohaline settings, and with low proportion of algal organic material showed higher OC densities, stocks, and accumulation rates. Grazing led to significantly higher OC stocks than neighboring ungrazed locations, likely due to trampling modifying soil abiotic conditions (higher erosion‐resistance and higher clay content) that slow carbon decay. Scaling up, Danish saltmarsh soils, comprising about 1% of the country's area, have the potential to yearly capture up to 0.1% of Denmark's annual consumption‐based CO2 emissions. Our research expands the baseline data needed to advance blue carbon research and management in the Nordic region while highlighting the need for a more comprehensive approach to saltmarsh management that considers the full range of services of these ecosystems and does not only focus on climate benefits. [ABSTRACT FROM AUTHOR]

The role of a landfill liner in the waste management process cannot be overemphasized. They are usually made of clay soils or geosynthetic materials or both with the sole purpose of controlling the migration of leachates into underlying aquifers and soils thereby preventing contamination. The limited availability of clay soils and high cost of geosynthetics have necessitated the search for and use of different locally available materials. Lateritic soils are one of the most commonly used materials for landfill liners in the tropical areas, where they commonly occur. However, a comprehensive review of literature on the utilization of lateritic soils as landfill liners has not been reported. Conducting a systematic review of lateritic soils for landfill liner applications enables an enhanced understanding of their inherent characteristics and appropriateness. This, in turn provides vital insights for the design and construction of effective and economically sustainable waste containment systems. Hence, this paper reviews the nature and characteristics of lateritic soils and assesses their suitability for landfill lining applications through a thorough evaluation of the desirable geotechnical, geological and geochemical properties based on available literature and data. Data on the index and geotechnical characteristics of lateritic soils at two hundred and seventy-eight locations from different countries were collected from literature and assessed based on standard specifications for landfill liners. Furthermore, their leachate attenuation characteristics and improving their suitability for landfill liners through property amendments are presented. The review results indicate that lateritic soils possess suitable engineering properties with some interesting clay mineralogical compositions for lining applications. In addition, the desirable geotechnical properties of lateritic soils can also be improved by blending it with bentonite, fly-ash, sawdust and mine tailings. Although mineralogical transformations occur after permeation with landfill leachates, lateritic soils possess contaminant attenuation characteristics such as low diffusion, good sorption and cation exchange properties that are needed for landfill liner applications. [ABSTRACT FROM AUTHOR]

Predictions of the unsaturated shear strength with generalized effective stress-based approaches disregard the non-uniform microstructure of remolded fine-grained soils. The study aims at investigating the adequacy of microstructurally-based effective stress to predict the unsaturated shear strength of remolded fine-grained soils over a wide range of suctions. For that purpose, shear strength data are acquired on a silty clay soil compacted at two different dry densities through suction-controlled triaxial tests and unconsolidated triaxial tests at constant water content. The microstructure of the soil at the as-compacted state is determined with mercury intrusion porosimetry and is directly incorporated in different expressions of microstructurally-based effective stress available in the literature. The experimental data suggest that compared to the generalized effective stress, microstructurally-based effective stress expressions provide better predictions of the unsaturated shear strength, especially at high suctions. Also, the use of microstructurally-based effective stress is particularly relevant for remolded fine-grained soils compacted at high dry densities, i.e., with a low proportion of macropores. [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]

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]

Copyright of Journal of Agricultural Sciences, Belgrade is the property of University of Belgrade, Faculty of Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lesser bandicoot rat, Bandicota bengalensis (Gray) burrows found complex with a fresh soil scoop at the entrance and ramified branches, galleries and bolt holes. Burrow length was more in light textured sandy soils, whereas burrow depth and branching were found more in heavy textured alluvial clay soils. Among the various soil properties, pH has shown a significant positive correlation with burrow depth (r = 0.51) and number of branches in a burrow (r = 0.50). Multiple linear regression analysis revealed that pH had a significant positive effect with circumference and branches, EC and bulk density with depth of the burrow, particle density and porosity with circumference of the burrow. Burrow temperature is always low over the soil and atmospheric temperatures in alluvial clay soils, but in sandy soils burrow temperature is relatively higher than soil temperature during lean period. [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]

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]

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]