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We have applied a recently developed general purpose acetonitrile force field based on first-principles calculations to simulate acetonitrile in the gas phase at different temperatures and densities. These conditions range from nearly ideal to real gas phase behavior and condensation. The molecular dynamics simulation results agree fairly well with the experimental studies available in the literature on the gas samples. The structural analysis of aggregates and their associated interaction energies is examined and related to the early model proposed on molecular association and equilibrium determining the non-ideal behavior. The formation of dimers is mainly responsible for the non-ideal behavior of the gas at very low density, confirming suggested models based on previous experimental studies. However, when the density of the sample rises, the level of aggregation increases and the simple concept of dimerization does not hold anymore. The real behavior adopted by the gas is related to the distribution of molecular structures observed. The macroscopical view of a real gas as a generic interparticle interaction system without a defined form may then be rationalized on the basis of a defined molecular association originated by a distribution of aggregates at the low density regime. The sample with the highest density (∼1.4 × 103 mol m−3) at the lowest temperature exhibits a massive aggregation where most of the acetonitrile (ACN) molecules in the simulation box form a big cluster. Its radial distribution function is similar to that of the liquid ACN. This strongly inhomogeneous distribution in the box can be considered a condensation in the gas phase under specific density-T conditions. This formation opens the door to the potential tuning of its solvent properties as a function of its size in these nanodroplets that in turn are controlled by the density–T conditions. [ABSTRACT FROM AUTHOR]

Currently, there is growing interest in Ag 2 O doping in oxide glasses through optimal selection of excitation wavelengths to achieve efficient luminescence via either up or down-conversion processes. In this present work, we report the influence of Ag nanoparticles/aggregates on the structural and spectroscopic characteristics of melt-quenched Ag 2 O - co-doped (19.5-x)Li 2 O+70B 2 O 3 +10CaO+0.5Nd 2 O 3 +xAg 2 O glasses. Systematic studies were conducted using XRD, Raman spectroscopy, HR-TEM, MAS-NMR, UV–Visible–NIR, Photoluminescence, and decay kinetics techniques. The XRD analysis conclusively indicates the absence of crystalline peaks. However, HR-TEM analysis showed a reduction in the size of AgNPs from 14 nm to 11 nm with an increase of Ag 2 O concentration from 0.25 mol% to 0.5 mol%, respectively. The RAMAN and MAS-NMR (11B and 7Li) revealed the modification in the local structure induced by the Ag 2 O as revealed by the predominant borate structural units, and silver (Ag) acted as a modifier in the glass matrix. The absorption spectra of all samples exhibit a characteristic peak of Nd3+ ions. Interestingly, the LCBNd0.5Ag0.5 glass sample exhibits the SPR peak at 416 nm, indicating that the lower limit of Ag 2 O in LCBNd0.5 is <0.5 mol%. Luminescence studies at different excitation wavelengths (350, 525, and 584 nm) reveal the predominant emission at 877 nm and 1058 nm, whose emission intensity increased with Ag 2 O concentration. Samples with Ag 2 O-doped LCBNd glasses exhibit identical lifetime values, indicating the absence of luminescence-quenching and the presence of Ag aggregates leading to the SPR effect. Based on our findings, the LCBNd0.5Ag0.5 sample demonstrated superior performance to other samples, with the highest emission under an excitation of 350 nm. [ABSTRACT FROM AUTHOR]

Suction stress is one of the most significant factors affecting the serviceability and stability of soil structures. This study presents a framework for analyzing the stability of geosynthetic reinforced soil (GRS) walls and slopes under unsaturated conditions. An analytical formulation of suction stress-based effective stress was implemented into a limit equilibrium solution, namely, the top-down procedure. The developed framework enables the prediction of the tensile load distribution and connection load between the reinforcement and wall face considering the pullout resistance of reinforcements in GRS walls backfilled with granular and marginal soils under unsaturated conditions. The applicability of the framework was demonstrated by providing an illustrative example followed by three series of parametric studies to understand the effects of pore size distribution, air entry pressure, and infiltration rate on the performance of an unsaturated GRS wall. The results quantify the impact of suction, showing that as it increases, the maximum tensile loads and connection loads decrease while pullout resistance increases. Mostly affected by the suction effect are upper reinforcement layers, where combined effects of reduced tensile load and increased pullout resistance decrease connection load and reinforcement length requirements. The current study strongly discourages counting on the contribution of suction for the design of new GRS walls. The suction value cannot be accurately and reliably determined for the entire lifespan of the GRS wall, and it may decrease or diminish in an uncontrolled and random manner under infiltration. However, by quantifying the effect of suction, the proposed framework in this study provides a valuable tool for analysis purposes, enabling a rigorous interpretation of field-measured reinforcement loads during wall service as well as evaluation of the forensics of failed GRS walls. [ABSTRACT FROM AUTHOR]

White matter (WM) changes occur throughout the lifespan at a different rate for each developmental period. We aggregated 10879 structural MRIs and 6186 diffusion-weighted MRIs from participants between 2 weeks to 100 years of age. Age-related changes in gray matter and WM partial volumes and microstructural WM properties, both brain-wide and on 29 reconstructed tracts, were investigated as a function of biological sex and hemisphere, when appropriate. We investigated the curve fit that would best explain age-related differences by fitting linear, cubic, quadratic, and exponential models to macro and microstructural WM properties. Following the first steep increase in WM volume during infancy and childhood, the rate of development slows down in adulthood and decreases with aging. Similarly, microstructural properties of WM, particularly fractional anisotropy (FA) and mean diffusivity (MD), follow independent rates of change across the lifespan. The overall increase in FA and decrease in MD are modulated by demographic factors, such as the participant's age, and show different hemispheric asymmetries in some association tracts reconstructed via probabilistic tractography. All changes in WM macro and microstructure seem to follow nonlinear trajectories, which also differ based on the considered metric. Exponential changes occurred for the WM volume and FA and MD values in the first five years of life. Collectively, these results provide novel insight into how changes in different metrics of WM occur when a lifespan approach is considered. [ABSTRACT FROM AUTHOR]

A five story (G + 4) residential structure is positioned on 15°, 30°, and 45° slopes to be explored in this study in terms of vulnegrability and compared to the same structure resting on flat ground 0°. The RC frame models were constructed in accordance with Eurocode 8 and then subjected through a series of 10 ground motion records. In accordance with Vision 2000 performance limit states (PLS), this research provided the use of nonlinear static analysis (NL-SA) and nonlinear dynamic analysis (NL-DA) methodologies to assess seismic risk performance and vulnerability of structures resting on various slope angles. Incremental Dynamic Analysis (IDA) and Pushover Analysis (POA) capacity curves, as well as the fragility curve and the collapse margin ratio, are generated for the four selected models (M0, M15, M30, M45). The results show that the RC frame model M45, located on a 45°-degree incline, is the most vulnerable to damage. The risk of damage to the RC frame M0 is minimal because it is not elevated off the ground. To this end, the relative degrees of vulnerability among the frames were determined to be as follows: M45 > M30 > M15 > M0. [ABSTRACT FROM AUTHOR]

The research attempts to provide a method for evaluating the susceptibility of heritage buildings and potential damage considering local site effects, using as a case study an urban sector situated in Horta, Faial, Azores, Portugal. The physical vulnerability of the investigated structures was appraised using an index-based method devised for structural masonry aggregates to emphasize their likelihood of seismic damage. As a result, a damage scenario based on real accelerograms collected after the 1998 Azores seismic event was developed by using a reliable seismic intensity prediction equation. In addition, the soil amplification, which increases the extent of seismic damage to the examined structures, is assessed by varying the soil conditions using EN 1998–1 Code. Thus, this research emphasises the ground impact in forecasting the expected damage scenarios, enabling optimised risk mitigation strategies in urban settings. [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]

In this investigation, the structural strength of a clayey soil compacted at three different dry densities (1.7, 1.6 and 1.5 Mg/m3) and three different compaction water contents (20%, 16% and 12%) was studied by using a micropenetrometer. The penetration curves at various water contents during the drying and wetting cycle were analyzed. The maximum unit penetration strength and the penetration stiffness were used to represent the structural strength. Experimental results show that the structural strength increases with decreasing water content. At a given water content, the larger dry density, the larger structural strength and the smaller hysteresis loop induced by the drying-wetting cycle. At a higher dry density, the structural strength increases and the drying-wetting cycle induced hysteresis loop becomes smaller. Specimens compacted on the wet side of optimum water content exhibit a dispersed structure and those compacted on dry side of optimum water content have an aggregated structure. For soils with a dispersed structure, the structural strength increases with decreasing water content and the growth rate is gradually accelerated. However, for soils with an aggregated structure, when dried to water content lower than 8%, the structural strength increases by a small degree or even decreases. Moreover, the hysteresis loop of the soil specimens with dispersed structure is much smaller than those with an aggregated structure. [ABSTRACT FROM AUTHOR]

Soil erosion is for the first time comprehensively studied in a catchment of 41 ha (near the village of Lomovets, Orel oblast) in the zone of gray forest soils (Luvic Phaeozems), which are considerably more susceptible to erosion as compared with chernozems. Analysis of archive data and historical cartographic materials shows that the catchment has been plowed for 200 ± 10 years. The rates of soil erosion and deposition over the entire cultivation period with/without taking into account soil self-restoration, last 50 ± 25 years, post-Chernobyl period (1986–2022), and the single erosion event on May 31, 2022 have been determined using field methods (soil- profile truncation, radiocesium technique, and rill methods, as well as a detailed UAV survey) and the model computations using the WaTEM/SeDEM model. The spatial distribution of soil erosion/deposition pattern is assessed. The estimates of soil losses and accumulation demonstrate considerable fluctuations in the rates of erosion and deposition over the past 200 years, which are mainly determined by the conditions of snowmelt runoff formation, repetition and distribution of runoff-forming rainfalls in the warm season, set of cultivated crops, tillage frequency and practices, and changes in field boundaries. The long-term average annual estimates of soil erosion over the agricultural period are higher than the estimates for the post-Chernobyl period, because the rates of soil erosion have decreased over the last 30 years. The WaTEM/SeDEM-based estimates of soil losses are generally comparable to the soil losses assessed according to soil morphology, provided that the redistribution of sediments to the lower boundaries of arable land is taken into account. The spatial structure of a single erosive event is to a considerable degree close to the spatial arrangement of the eroded and aggraded soil areas formed over the entire agricultural period. [ABSTRACT FROM AUTHOR]

Influence of recycled aggregate on the bond behaviour of reinforcing steel in concrete The use of recycled aggregates in common structural concretes is considered a promising approach to conserve natural resources. The present study focuses on investigating the bond behaviour of reinforcing steel in concrete with high portions of recycled aggregate from crushed concrete. To clarify a possible influence of the aggregate properties, 5 different aggregates were tested in 12 concretes. The results of the pull‐out tests were evaluated with the help of an analytical bond equation to be able to draw conclusions about the resulting design bond stress. A tendency towards a decrease in the maximum absorbable bond stress with high portions of recycled aggregate was observed. The resulting design values of the bond strength are lower than for the reference concrete, but above the specifications of Eurocode 2. The decrease in the design bond stress appears to correlate with the volume fractions of recycled aggregate and the concrete bulk density. Overall, the study shows that the bond behaviour of concrete with recycled aggregate is similar to that of normal concrete in terms of bond, shear and friction, although the actual effects also depend on the specific properties of the aggregate used. [ABSTRACT FROM AUTHOR]

Agricultural practices alter the organic carbon dynamics in soil. An experiment was conducted to study the effect of carbon amendments, tillage, and cover cropping on permanganate oxidizable carbon (POXC), total organic carbon (TOC), and wet aggregate stability (WAS) in a 2‐year crop sequence (corn–cover crop–cotton–cover crop) at the Texas A&M Research Farm. Two carbon amendments (biochar and composted biosolid) were applied at the rate of 500 kg C ha−1, along with a control. Two tillage practices were evaluated: conventional tillage (CT) and no‐tillage (No‐Till). A cover crop (CC) mixture of oat, mustard, and pea and no cover crop (No‐CC) were also evaluated. Treatments were arranged in a split‐split plot design with four replications. Amending the soil with carbon as composted biosolid or biochar affected POXC at both the 0‐ to 5‐ and 5‐ to 15‐cm depths. The POXC was significantly higher for the biochar treated plots for corn and CC after corn but significantly lower POXC was observed after cotton with biochar‐treated plots. The POXC increased under No‐Till compared with CT and CC plots relative to No‐CC plots. The TOC was not sensitive to soil management practices. The POXC and TOC both decreased with depth. The WAS greater under No‐Till and CC plots. The POXC and WAS were influenced by soil management practices and can be useful indicators to assess short‐term soil health improvements. The POXC and WAS were positively related, suggesting that one may be used to predict the other. Core Ideas: Permanganate‐oxidizable carbon (POXC) was sensitive to management practices compared to total organic carbon.POXC was greater on no‐tillage compared to conventional tillage.POXC was higher on cover cropped than no cover cropped plots.Soil aggregate stability was positively correlated with POXC.Wet aggregate stability was greater under biochar amended, no‐tillage, and cover cropped plots. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) plays a significant role in climate change. Its content can be modified by soil management practices, however, the effect of mineral fertilization on SOC is not clear. For this reason, a long-term effect of gradually increasing rates of NPK fertilizers on changes in soil organic carbon (SOC) in bulk soil and in water-stable aggregates (WSA) in soils with sandy loam and loamy sand texture at two experimental sites (Skierniewice, Poland, and Dražovce, Slovakia) was quantified. In both sites, soil samples were collected from the following treatments: NF – no fertilization, NPK1 and NPK2 – 1st level and 2nd level of NPK fertilization, respectively. The results showed that 100-year long application of NPK1 increased total carbon (TC) and SOC content by 24%, while NPK2 decreased it by 5% compared to NF at the Skierniewice site. The content of water-stable macroaggregates (WSAma) increased because of NPK application. In NPK1, the content of WSAma was higher and the content of water-stable microaggregates (WSAmi) was lower than in NPK2 or NF. However, as a result of NPK application, the content of agronomically favorable WSAma in size fraction 0.5–3 mm was reduced by 8 and 24% in NPK1 and NPK2, respectively, compared to NF. Overall, SOC in WSAma was lower than in bulk soil. The SOC in WSAma in NF, NPK1 and NPK2 treatments was 6.51, 7.77 and 5.89 g.kg−1, respectively. Similar tendency of SOC in WSAma 0.5–3 mm was observed (NF: 6.12 g.kg−1, NPK1: 7.35 g.kg−1, and NPK2: 6.88 g.kg−1). The SOC in WSAmi in NF, NPK1 and NPK2 was 8.33, 7.39 and 7.24 g.kg−1, respectively. At Dražovce site, TC content decreased significantly due to the graded rates of NPK, not because of SOC mineralization but as a result of carbonate dissolution for a period of 14 years. The carbonate content decreased from 20 g.kg−1 in NF to 6.5 g.kg-1 in NPK1 and 3.0 g.kg-1 in NPK2, while SOC did not change significantly: (NF: 23.8 g.kg−1, NPK1: 25.9 g.kg−1, and NPK2: 23.4 g.kg−1). In NPK1, the WSAma content was reduced significantly when compared to NPK2 and NF treatments. No significant difference was observed between NF and NPK2. On the contrary, the content of WSAma 0.5–3 mm significantly increased when compared to NF and NPK1. No difference was observed between NF and NPK1. Lower SOC content was found in WSA than in the bulk soil. Overall, higher SOC content was observed in WSAma when compared with WSAmi. The application of NPK1 and NPK2 increased SOC in WSAma as well as in WSAma 0.5–3 mm. The effect was more significant in NPK1 than NPK2 treatments when compared to NF. [ABSTRACT FROM AUTHOR]

Organic amendment has proven to improve soil quality and crop production, in addition to reduce resource waste. However, the effect of organic amendment on soil water-stable aggregates and soil organic carbon is unclear. A two-year field experiment with four organic amendment treatments, biochar, organic fertilizer, microbial agents and polyacrylamide (PAM), was conducted to investigate the effect of different soil organic amendments on Loess Plateau. The results revealed that organic amendments significantly influenced the mean weight diameter (MWD) and geometric mean diameter (GMD) of water-stable aggregates, particularly in the case of PAM treatment. The MWD and GMD values increased significantly by 33.7% and 29.8% in the PAM treatment. The proportion of macroaggregates (2-0.25 mm) showed a remarkable 52.9% increase compared to the control (CK) treatment in the PAM-treated soil. Biochar-amended treatments increased soil organic carbon (SOC) in all aggregate fractions compared to CK treatment. Soil organic amendments also decreased soil bulk density and increased total nitrogen (TN) and available phosphorus (AP). Compared to CK treatment, the maize yields in the organic fertilizer and biochar treated soil increased by 19.8 and 30.3%, respectively. These findings suggest that biochar and PAM amendments are particularly suitable for loessal soil in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

The construction of deep foundation pits that are adjacent to an operating subway tunnel can cause significant disturbance to the surrounding soil and tunnel structure. Assessing the stability of the soil in the security area of the tunnel is key to controlling the displacement of the tunnel structure. Assuming that the soil behind the wall is in the elastic stage of small deformation, the unloading stress distribution law of the soil on the excavation surface of the side wall is inversely calculated using the horizontal displacement curve of the retaining structure. Based on the analytical solutions for the horizontal displacement and surface settlement of the soil behind the wall proposed in this paper, the spatial distribution characteristics of the deformation transfer of the soil in the security area are obtained. Considering the interaction between the soil in the security area and the tunnel structure, by simplifying the soil in the security area to a Pasternak foundation model, the tunnel displacement that is caused by deformation transfer can be obtained. The correctness of the theoretical model is verified by comparing it with the measured data for the soil displacement behind the wall and the tunnel structure in project cases of foundation pit excavation. [ABSTRACT FROM AUTHOR]

This study integrated bacterial community and soil chemicals to characterize the soil ecosystem in an open upland field managed by six controlled fertilizer programs using the minimum amount of pesticides. Amplicon sequencing the 16S rRNA gene revealed that inorganic nitrogen fertilizer and compost altered the diversity and structure of the soil bacterial community throughout buckwheat (Fagopyrum esculentum Moench 'Hitachiakisoba') cultivation. The bacterial community comprised three clusters that contained bacteria that are prevalent in soils fertilized with nitrogen (cluster 1, 340 taxa), without nitrogen and compost (cluster 2, 234 taxa), and with compost-fertilized (cluster 3, 296 taxa). Cluster 2 contained more taxa in Actinobacteriota and less in Acidobacteriota, and cluster 3 contained more taxa in Gemmatimonadota compared with the other clusters. The most frequent taxa in cluster 1 were within the Chloroflexi phylum. The bacterial community structure correlated with soil chemical properties including pH, total organic carbon, SO42−, soluble Ca2+. A co-occurrence network of bacterial taxa and chemicals identified key bacterial groups comprising the center of a community network that determined topology and dynamics of the network. Temporal dynamics of the bacterial community structure indicated that Burkholderiales were associated with buckwheat ripening, indicating plant-bacteria interaction in the ecosystem. [ABSTRACT FROM AUTHOR]

Data assimilation is an essential approach to improve the predictions of land surface models. Due to the characteristics of single-column models, assimilation of land surface information has mostly focused on improving the assimilation of single-point variables. However, land surface variables affect short-term climate more through large-scale anomalous forcing, so it is indispensable to pay attention to the accuracy of the anomalous spatial structure of land surface variables. In this study, a land surface image assimilation system capable of optimizing the spatial structure of the background field is constructed by introducing the curvelet analysis method and taking the similarity of image structure as a weak constraint. The fifth-generation ECMWF Reanalysis – Land (ERA5-Land) soil moisture reanalysis data are used as ideal observation for the preliminary effectiveness validation of the image assimilation system. The results show that the new image assimilation system is able to absorb the spatial-structure information of the observed data well and has a remarkable ability to adjust the spatial structure of soil moisture in the land model. The spatial correlation coefficient between the model surface soil moisture and observation increased from 0.39 to about 0.67 after assimilation. By assimilating the surface soil moisture data and combining these with the model physical processes, the image assimilation system can also gradually improve the spatial structure of soil moisture content at a depth of 7–28 cm, with the spatial correlation coefficient between the model soil moisture and observation increased from 0.35 to about 0.57. The forecast results show that the positive assimilation effect could be maintained for more than 30 d. The results of this study adequately demonstrate the application potential of image assimilation system in short-term climate prediction. [ABSTRACT FROM AUTHOR]

There is an increasing need for accessible methods to monitor soil health. Our primary objective was to evaluate an accessible, do-it-yourself method for measuring the maximum water holding capacity – we call this the funnel, filter paper, and drainage (MWHCFFPD) method. First, we compared MWHCFFPD to the water desorption method via pressure cells (WHCPC), routinely used for generating soil water retention curves, using 10 soils from a wide range of textures (4–55% clay). Second, we tested the sensitivity of the MWHCFFPD to methodological variations likely encountered by citizen scientists. The two methods were quite comparable in precision, with mean coefficient of variances of 3.5% and 4.4% for the FFPD and water desorption method, respectively. The MWHCFFPD and WHCPC methods were comparable, with MWHCFFPD best correlating to WHCPC at −2.45 kPa (R2 = 0.98). The MWHCFFPD method is somewhat sensitive to some methodological modifications, most notably variation in water source, but with standardized protocols could be scientifically robust. Overall, MWHCFFPD can be used as a simple and affordable test of sieved soil structure and organic matter, and thus has potential to expand soil health monitoring. [ABSTRACT FROM AUTHOR]

Summary: Biophysicochemical rhizosheath properties play a vital role in plant drought adaptation. However, their integration into the framework of plant drought response is hampered by incomplete mechanistic understanding of their drought responsiveness and unknown linkage to intraspecific plant–soil drought reactions.Thirty‐eight Zea mays varieties were grown under well‐watered and drought conditions to assess the drought responsiveness of rhizosheath properties, such as soil aggregation, rhizosheath mass, net‐rhizodeposition, and soil organic carbon distribution. Additionally, explanatory traits, including functional plant trait adaptations and changes in soil enzyme activities, were measured.Drought restricted soil structure formation in the rhizosheath and shifted plant–carbon from litter‐derived organic matter in macroaggregates to microbially processed compounds in microaggregates. Variety‐specific functional trait modifications determined variations in rhizosheath drought responsiveness. Drought responses of the plant–soil system ranged among varieties from maintaining plant–microbial interactions in the rhizosheath through accumulation of rhizodeposits, to preserving rhizosheath soil structure while increasing soil exploration through enhanced root elongation.Drought‐induced alterations at the root–soil interface may hold crucial implications for ecosystem resilience in a changing climate. Our findings highlight that rhizosheath soil properties are an intrinsic component of plant drought response, emphasizing the need for a holistic concept of plant–soil systems in future research on plant drought adaptation. [ABSTRACT FROM AUTHOR]

The processes of occupation and exploitation in the Amazon have been increasing, and as a consequence, forest areas are being replaced by agroecosystems. As a consequence of this change, changes have been occurring in the soil attributes, and consequently, in the stability of aggregates in these environments. Thus, this work had two objectives: the first was to evaluate the impacts generated by the conversion of forests into agroecosystems on the soil attributes that are related to aggregates, in the southwestern region of the Amazon; the second objective was to evaluate the roles of pedophysical and pedochemical parameters on the stability of soil aggregates. The study was carried out on rural properties located in the southern part of Amazonas State, Brazil. Eight areas under different agroecosystems were selected: in the municipality of Canutama: (i) annatto, (ii) guarana, and (iii) cupuassu; in the municipality of Humaitá: (iv) cassava, (v) agroforestry, and (vi) sugarcane; and in the municipality of Manicoré: (vii) pasture and (viii) native forest. Unformed soil samples were collected from the 0.00–0.10 m layer and analyzed for aggregate stability, bulk density, soil organic carbon, and soil organic carbon stock. Univariate, bivariate, and multivariate analyses were performed. The largest soil aggregations occurred in the annatto, guarana, sugarcane, and pasture agroecosystems. We associate the greater aggregation capacity of soils with factors that are inherent to the cultivated species and soil properties. The first factor corresponds to the adaptability of the Amazonian and grass species and their ability to produce biomass. The second factor is related to the physical and chemical properties of Amazonian soils, largely influenced by the sand fraction, soil organic carbon, soil acidity, and availability of exchangeable Ca and Mg. [ABSTRACT FROM AUTHOR]

Background and Aims The successful plant Fallopia  ×  bohemica presents interesting capacities for control of the soil nitrogen cycle at the adult stage, termed biological inhibition of denitrification (BDI). The BDI strategy allows the plant, via the production of secondary metabolites (procyanidins), to compete with the denitrifying microbial community and to divert nitrate from the soil for its benefit. In this study, we analysed whether seedlings of F.  ×  bohemica can implement BDI at the seedling stage. We also determined whether soil nitrogen availability influences the implementation of BDI and seedling growth. Methods We sowed achenes of F.  ×  bohemica in soils representing a nitrogen gradient (six treatments) and harvested seedlings after 20 or 40 days of growth. The denitrification and related microbial communities (i.e. functional gene abundances of nirK and nirS), soil parameters (nitrate content and humidity) and plant performance (biomass, growth and root morphology) were determined. Key Results On soil without addition of nitrogen, BDI was observed after 20 days of growth, whereas a stimulation of denitrification was found after 40 days. The increase of soil N content had few effects on the activity and structure of the soil denitrifying community and on the plant biomasses or the relative growth rates. Correlations between plant and microbial parameters were observed after 20 days of growth, reflecting early and strong chemical interactions between plants and the denitrifying community, which decreased with plant growth after 40 days. Conclusions This study shows that an early BDI enhances the efficiency of nitrogen acquisition in the first weeks of growth, allowing for a conservative root strategy after 40 days. This switch to a conservative strategy involved resource storage, an altered allocation to above- and below-ground parts and an investment in fine roots. It now seems clear that this storage strategy starts at a very young age with early establishment of BDI, giving this clonal plant exceptional capacities for storage and multiplication. [ABSTRACT FROM AUTHOR]

Soil enzyme activities are closely associated with soil organic carbon (SOC) or microbial biomass carbon (MBC). High correlation between SOC and MBC masks their individual effects on enzyme activities. Expressing soil enzymes activity relative to soil organic carbon (SOC) or Microbial Biomass Carbon (MBC) would normalize the differences in SOC/MBC. A long term subtropical rice-wheat system was selected to study the variation in soil-specific enzyme activity (per unit SOC and MBC) in soil aggregates under integrated nutrient management. Soil organic carbon, microbial biomass carbon and the enzyme activities like acid phosphatase (ACP), alkaline phosphatase (AKP), dehydrogenase (DHA), fluorescien diacetate hydrolysing capacity (FDA) and urease were measured in three aggregate size fractions viz., >2000, 2000–250 and <250 µm. Integrated nutrient management practices significantly increased the specific enzyme activities expressed in relation to SOC and MBC. Aggregate size fractions of 2000–250 µm size exhibited higher specific enzyme activities, when expressed in terms of SOC. Enzyme activity (per unit MBC) in aggregates also followed the same pattern with an exception to dehydrogenase activity which was almost uniform across all the aggregates size fractions. Aggregates of larger size do not always possess higher enzymes activity; even smaller macroaggregates were able to retain stable extracellular enzyme activity per unit of SOC or MBC. This study opens an alley to express soil enzymatic activities relative to SOC or MBC level in the soils, rather than expressing absolute activities. [ABSTRACT FROM AUTHOR]

Ester materials have become a significant topic in ecological restoration because of their degradability and lack of pollution. However, these artificial materials have issues such as high resource consumption and high cost. Therefore, finding a scientific substitute for ester materials is crucial to reduce costs. This study proposes the use of weathered red-bed soil to partially replace ester materials. Orthogonal coupled compounding and ecological effect tests were performed to analyze the soil improvement mechanism based on the mineral composition, soil structure, and electrical conductivity properties of the weathered red-bed soil. The experimental findings indicated that the soil modified using ester materials exhibited improved strength, water retention, and aeration owing to changes in the soil structure. Plant germination and height increased by 55% and 37 mm, respectively, when using a ratio of 15 g/m2 absorbent ester material, 2.5 g/m2 adhesive ester material, and 5% weathered red-bed soil. Through this approach, the amount of ester material to be used could be further reduced by 75%. The weathered red-bed soil offers improved ecological effects by altering the physical, mechanical, and hydraulic properties of the soil structure. This study presents a theoretical foundation for ecological conservation using weathered red-bed soil as a substitute for certain ester materials. [ABSTRACT FROM AUTHOR]

Whether soil structure should be viewed mostly as a system of pores or a set of aggregates is a question soil scientists keep debating in the literature, but it is unclear whether the wider soil science community is also divided. In a quick survey among mainly German soil scientists of all career levels and sub‐disciplines, most participants agreed that both pores and aggregates are important to describe soil structure. The debate can nevertheless be fruitful if it is led more efficiently, avoiding generalisations, misunderstandings and potential emotional barriers. [ABSTRACT FROM AUTHOR]

The ectomycorrhizal fungi Tuber melanosporum Vittad. and Tuber aestivum Vittad. produce highly valuable truffles, but little is known about the soil fungal communities associated with these truffle species in places where they co-occur. Here, we compared soil fungal communities present in wild and planted truffle sites, in which T. melanosporum and T. aestivum coexist, in Mediterranean and temperate regions over three sampling seasons spanning from 2018 to 2019. We showed that soil fungal community composition and ectomycorrhizal species composition are driven by habitat type rather than climate regions. Also, we observed the influence of soil pH, organic matter content and C:N ratio structuring total and ectomycorrhizal fungal assemblages. Soil fungal communities in wild sites revealed more compositional variability than those of plantations. Greater soil fungal diversity was found in temperate compared to Mediterranean sites when considering all fungal guilds. Ectomycorrhizal diversity was significantly higher in wild sites compared to plantations. Greater mould abundance at wild sites than those on plantation was observed while tree species and seasonal effects were not significant predictors in fungal community structure. Our results suggested a strong influence of both ecosystem age and management on the fungal taxa composition in truffle habitats. [Display omitted] [ABSTRACT FROM AUTHOR]

Aimes: Vegetation restoration in post-mining land is one of the most important remediation strategies for rebuilding the soil carbon (C) pool and improving soil quality. We aimed to provide a global perspective on the effects of vegetation restoration on soil properties. Methods: By analyzing a database of 2799 observations extracted from 160 publications, we quantitatively assessed the effects of vegetation restoration on soil C, water holding capacity, electronic conductivity (EC), cation exchange capacity (CEC), and soil structure in post-mining land across the globe. Results: The results showed that (1) vegetation restoration significantly increased soil organic C (SOC) stock (averagely + 112%), dissolved organic C (DOC) concentration (+ 141%), water content (SWC, + 40%), saturated water content (SSWC, + 40%), hairy tube holding water (HTHW, + 29%), CEC (+ 19%), and the concentrations of sand (+ 17%) and silt (+ 11%), while decreased the EC (-22%) and pH (-7.1%); (2) vegetation type could mediate the effects of vegetation restoration on HTHW, CEC, and sand and silt concentrations, while mineral type of metal mine influenced the effects of vegetation restoration on pH, CEC, bulk density, and sand and silt concentrations; and (3) plant diversity positively affected the effects of vegetation restoration on soil DOC concentration and pH, whilst the effects of soil depth, climate, and restoration year varied for different variables of soil properties. Conclusions: These results suggested a critical role of vegetation restoration in the remediation of post-mining land. [ABSTRACT FROM AUTHOR]

Biochar is an effective ameliorator for soil quality improvement and nutrient reuse from biomass; however, the effect of biochar application on soil potassium (K) availability, plant K uptake, and the underlying mechanisms have not been well‐elucidated. To address this, the variation in the soil K forms, soil aggregate stability, and aggregate‐associated K concentration, as well as maize K uptake, were investigated in a field experiment after 9 years of biochar amendment. The treatments included no biochar and NPK fertilizer (CK); NPK fertilizer treatment (F); biochar applied annually at the rate of 2.625 t ha−1 (C1), and biochar applied annually at rate of 2.625 t ha−1 with NPK fertilizers (C1F); one‐time biochar applied with NPK fertilizers, with biochar rate of 31.5 (C2F) and 47.25 t ha−1 (C3F). The results showed that after 9 years of field application, biochar inhibited the downward K migration to the deeper layer, thus increasing water‐soluble potassium (WSK), exchangeable potassium (EK), non‐exchangeable potassium (NEK), and total potassium (TK) in 0–20 cm soil, with C1F exhibiting better performance than C2F and C3F. Biochar also increased aggregate‐associated EK, NEK, and TK pools, mainly due to an increase in the macroaggregate proportion (>0.25 mm). Biochar amendment promoted maize K uptake by an average of 35.69%, the path analysis indicated that the positive effect was an outcome of the synergetic effect of the increase in surface soil WSK content and promoted macroaggregate EK pools, which was primarily attributed to biochar improved soil properties, including soil organic carbon, pH, total nitrogen, total phosphorus, and cation exchange capacity. These factors explained 76% of the variance in maize K uptake. In conclusion, biochar is an effective ameliorator for improving soil K content and availability. [ABSTRACT FROM AUTHOR]

The mechanical behaviour of clayey loess is strongly affected by the soil structure, but although anisotropy has been identified in loess by some, the anisotropy of small-strain behaviour is rarely reported. This paper presents an experimental study on the inherent and stress-induced small-strain shear stiffness anisotropy of a clayey loess from China. Both undisturbed and reconstituted specimens were tested with bender elements under isotropic compression and shearing conditions. Under an isotropic stress state, an inherent anisotropy was found for undisturbed specimens, while the reconstituted specimens prepared by moist tamping behaved isotropically. During shearing, the ratio of horizontal to vertical shear moduli of the undisturbed specimens decreased due to both an increase of stress anisotropy and the destruction of the intact structure. In contrast, the stiffness ratio of the reconstituted specimens only decreased due to stress anisotropy and it became more anisotropic at the critical state. This study reveals the influence of intact structure and inherent anisotropy on the behaviour of loess soils, which cannot be reproduced by compaction, thus highlighting the importance of characterising the undisturbed loess. [ABSTRACT FROM AUTHOR]

Using carbon-based materials (CBMs) to facilitate phytoremediation shows great promise for simultaneously enhancing the restoration efficiency of contaminated soil and reducing carbon dioxide in the context of global warming, which is still in the exploring and attempting phase. In addition to direct degradation or alteration of pollutant bioavailability, CBMs can enhance phytoremediation by alleviating plant nutrient deprivation and oxidative stress, as well as by modulating soil microbial communities and root secretions. Photosynthetic carbon fixation predominantly affects both phytoremediation efficiency and carbon cycle turnover in terrestrial ecosystems. In this regard, CBMs have extremely positive properties in facilitating plant carbon capture, with intrinsic mechanisms including (1) promoting photosynthetic pigment synthesis and acting as artificial built-in antennae to improve photon capture efficiency, (2) accelerating the photosynthetic electron transport rate in photosystems, (3) improving the Calvin cycle, and (4) maintaining the structural integrity of chloroplasts. Besides, as an ultra-stable type of CBM derived from waste biomass, biochar can preserve the native biomass carbon in the soil environment for decades and attenuate the rhizosphere priming effect by influencing the structure of rhizosphere soil aggregates and microbial communities, thus retarding the native soil organic carbon efflux. This review critically elaborates on the mechanisms by which CBMs assist in improving the efficiency of phytoremediation and their positive effects on the plant-root soil carbon balance. Additionally, a simple full-life cycle analysis encompassing cost analysis as well as ecological, economic, and social benefits is concluded to evaluate the feasibility and sustainability of CBMs-phytoremediation systems. [ABSTRACT FROM AUTHOR]

Shanghai clay exhibits overconsolidation, soil structural, and small-strain characteristics. While there have been several studies on the effects of small-strain characteristics on the deformation caused by deep excavation, the effects of overconsolidation and structural behaviors on this deformation remain unexplored. Therefore, in this study, a constitutive model considering the aforementioned three characteristics is developed and then implemented in the commercial software program FLAC3D (version 7.00) to investigate the effects of overconsolidation and structural behaviors. Initially, validation and parametric study of the constitutive model are conducted based on a cylindrical numerical model. Subsequently, the constitutive model is validated by a well-documented case history of a deep excavation in Shanghai. Thereafter, the effects of overconsolidation and structural behaviors on wall deflection and ground settlement induced by deep excavation are investigated. It is observed that overconsolidation has a significant effect on the deformation induced by deep excavation, while the effect of soil structure is negligible. With an increase in excavation depth, the effect of overconsolidation on the deformation increases, and its effect on ground settlement is more significant than that on wall deflection. According to the results of the parametric study, it is revealed that by the time the shear strain induced by deep excavation reaches a maximum value, overconsolidation has partially degraded while soil structure has not yet collapsed, which accounts for the magnitude of the aforementioned effects induced by deep excavation. [ABSTRACT FROM AUTHOR]

Climate change and salt-affected soils detrimentally affect crop production in arid regions. Reclaiming these soils for crops and carbon sequestration can mitigate climate change and enhance food security. A laboratory-scale experiment was conducted on a wheat-maize crop rotation system for three consecutive years to check the effectiveness of organic amendments in reclaiming marginally salt-affected soils, improving soil health, sequestering carbon, and improving food grain production. This study included five treatments namely control (T1), gypsum alone at 100% gypsum requirements (G100), and its combinations with different organic amendments and 50% gypsum requirements (farm manure (FYM+G50), poultry manure (PM+G50), and green manure (GM+G50)) were used. Results indicated that sandy clay loam textured soil showed highest potential for its properties improvement after 45 days, i.e., EC decreased up to 3.9 dS m−1, pH 7.9 and, SOC increase up to 0.25%. After the fallow period, three consecutive years of crop production study indicated up to 39 and 70% increase in wheat and maize yields, respectively, compared to inorganic fertilizer alone. Maximum soil aggregation was noted in treatment with gypsum and farmyard manure application in loam soils (50%). The maximum soil organic carbon accumulation over the whole experiment was recorded in farmyard manure application in combination with gypsum (0.44 g kg−1) in both loam and sandy clay loam soil, while 0.31 g kg−1 in the clay loam soil. Based on the results, it was concluded that reclaiming marginally salt-affected soils enhances food crop production and incorporating manures improves soil through aggregation and carbon sequestration, mitigating climate change. [ABSTRACT FROM AUTHOR]

Investigating the impact of train-induced vibration loads on soil hydraulic properties, this study conducted experiments using a self-designed indoor soil seepage platform that incorporates vibration loads. The experiments were complemented with scanning electron microscopy to analyze the influence of train-induced vibration loads on soil hydraulic conductivity and its evolutionary characteristics under different vibration frequencies. The experimental results indicated that as the vibration frequency increases from no vibration (0 Hz) to 20 Hz, the time required for the soil volumetric moisture content to reach its peak and stabilize decreases rapidly. However, after the vibration frequency exceeds 20 Hz, the rate at which the time required for the volumetric moisture content to reach its peak and stabilize decreases slows down. Furthermore, the soil pore water pressure increases with the increase in vibration frequency. At a vibration frequency of 80 Hz, the peak value of pore water pressure increases by 105% compared to the non-vibration state, suggesting that higher vibration frequencies promote the development and acceleration of soil pore moisture migration. Additionally, as the vibration frequency increases, the soil hydraulic conductivity initially experiences a rapid increase, with a growth rate ranging from 40.1 to 47.4%. However, after the frequency exceeds 20 Hz, this growth rate significantly decreases, settling to only 18.6% to 7.8%. When the soil was subjected to a vibration load, the scanning electron microscopy test revealed alterations in its pore structure. Micropores and small pores transformed into macropores and mesopores. Additionally, the microstructural parameters indicated that vibration load decreased the complexity of soil pores, thereby speeding up the hydraulic conduction process. This, in turn, affected the hydraulic properties of the soil and established a relationship between pore structure complexity and soil hydraulic properties. [ABSTRACT FROM AUTHOR]

Biochar is increasingly recognized for its ability to enhance hydro-physical properties of soil, offering promising solutions for improving soil structure, water retention, and overall agricultural productivity. In this study, sandy loam soil was amended at different rates (0, 15, 30, and 60 t ha−1) of biochar produced from olive pomace (Jift) at different pyrolysis temperatures (300, 400, 500, and 600 °C), and incubated for 30, 60, and 90 days. The biochar-amended soils were collected for analysis after each incubation period for infiltration rate, aggregate stability, soil water retention, water repellency, and penetration resistance. At 300 °C, aggregate stability increased with biochar amendments; the highest value (65%) was after 60 days of incubation. At other pyrolysis temperatures, aggregate stability decreased, or no effect of temperature was observed. Also, at 300 °C, the infiltration rate was decreased with biochar application and the lowest value of (0.14 ml/min) was at 90 days of incubation. At other pyrolysis temperatures, the infiltration rate was increased with increased biochar application rate. Water retention was increased with biochar application at 300 °C; however, biochar application did not affect water retention at other pyrolysis temperatures. These results strongly suggest the improvement of soil physical and hydraulic properties following the addition of biochar amendment. Overall, biochar had positive effects on hydro-physical properties. The biochar produced at 300 °C pyrolysis temperature was the most beneficial to agriculturally relevant hydraulic conditions. However, field assessments are necessary to evaluate the long-term effects of biochar on hydro-physical properties. [ABSTRACT FROM AUTHOR]

Soil structure and overconsolidation are two important factors that affect soil strength. Current research studies have primarily focused on the influence of single factors, and relatively few studies have studied the coupling effect of the two. In this paper, the effects of structure and overconsolidation on the mechanical properties of loess under certain conditions have been studied by compression tests and direct shear tests. Undisturbed loess, remolded loess, overconsolidated undisturbed loess, and overconsolidated remolded loess were investigated in this work. The results indicate that structure and overconsolidation can enhance the overall strength of the soil, but the effects of these two factors also interfere and weaken each other. The combined effect of structure and overconsolidation can lead to higher soil shear strength. Compared with remolded normally consolidated soil, when the vertical pressure is 50kPa, 100kPa, and 200kPa, the structure increases the strength of the original normally consolidated soil by 35%, 21%, and 7%, respectively. Overconsolidation increases the strength of the remolded overconsolidated soil by 51.3%, 40.9%, and 17.7%, respectively. The combined effect of structure and overconsolidation increases the strength of the original overconsolidated soil by 89%, 72.5%, and 32.7%, respectively. The increase in soil strength caused by the coupling effect is smaller than the sum of the strength increase caused by the two factors. The main reason is that the soil structure can reduces the compaction effect of overconsolidation, and the compaction load applied during the process of overconsolidation can also damage the soil structure, and the scanning electron microscopy observation is consistent with the experimental results and analysis. Finally, an empirical relation was developed for the effect of overconsolidation, structural properties, and their coupling on soil strength. The calculated results of the formula are highly consistent with the experimental data, and have good rationality and accuracy. [ABSTRACT FROM AUTHOR]

Application of biofertilizers (BFs) is very important for the development of sustainable agriculture. These eco-friendly bioproducts improve soil structure and enhance its fertility and crop productivity. The usage of BFs may reduce or totally exclude the amount of chemical fertilizers, at the same time helps to receive residue free, safe and healthy crops. The application of BFs in hydroponic culture is especially important as soilless production of crops is totally based on the usage of synthetic fertilizers and the replacing them with these environment-friendly substances may be a good alternative. This review article is summarizes studies on application of BFs in soilless conditions. The article includes short information about BFs and hydroponics, the ways of application of BFs, the combined usage with inorganic nutrients, as well as the role on the nitrate accumulation in hydroponic conditions. [ABSTRACT FROM AUTHOR]

Hydraulic structures, such as shiplocks, are typically surrounded by backfills, leading to various contact interactions between the backfills and the outer surfaces of the structures. To investigate the evolution of contacts under different loading conditions across the entire structure and to explore the influences of contacts on stress distributions between the shiplock structure and soil, three-dimensional numerical analysis was conducted on the lock head of a shiplock, considering various loading scenarios and contact interactions. Results show that, the opening areas and displacements on the contact surfaces vary significantly during different phases of the construction and operation of the hydraulic structure. The entire process can typically be divided into pouring, backfilling, and water-filling phases, with the backfilling phase showing the largest opening displacement. Compared to calculations without considering the contact, the relative peak maximum principal stress can increase by up to 18.85% when the contact is taken into account, and its peak value is reached after the backfilling process being completed. The conclusions obtained in this study can offer the theoretical and practical references for the design of hydraulic structures and the assessment of their safety. [ABSTRACT FROM AUTHOR]

Intensification of crop sequence (ICS) has been proposed as a key field practice to preserve soil health and achieve more sustainable agricultural systems. However, the effects of ICS are site‐specific and vary according to soil characteristics, climatic conditions, the duration of the crop sequencing and the types of crop involved. Soil aggregate stability (AS) and soil organic carbon (SOC) stock are useful indicators of soil health as they are closely linked to diverse soil services and functions and are sensitive to management practices. We performed a meta‐analysis of 33 studies to analyse the impact of ICS on SOC stock and AS in field experiments in the central‐eastern region of Argentina. Our results showed that ICS increased SOC stock and AS, with an overall mean change of 7% and 22%, respectively. Fine‐textured soils showed the greatest SOC stock increase (12%), comparable to the increase observed in coarse‐textured soils (11%); in medium‐textured soils this increase was less than half (5%). Coarse‐textured soils had the greatest increase in AS (32%), followed by medium‐textured and fine‐textured soils, which also showed notable improvements (25% and 19%, respectively). Greater diversity of crops resulted in larger increases in both AS and SOC. ICS generated a larger increase of SOC stock in the soil surface (0–10 cm) than in the subsurface (10–20 cm), whereas the opposite was found for AS. Long‐term studies (≥9 years) had the greatest effect on AS and SOC stock. Regression analysis revealed that the initial carbon stock influenced SOC stock results following ICS, increases being greater when initial carbon stock contents were smaller. Introducing gramineous species into the crop sequence was associated with a greater improvement of AS and SOC stock. Finally, the mean rate of carbon sequestration from ICS in all the studies amounted to 0.28 Mg ha−1 yr−1. Overall, ICS is a useful strategy for improving SOC storage and AS in this region, though results may vary according to soil characteristics and management practices. [ABSTRACT FROM AUTHOR]

The structure of soil is critical for the ecosystem services it provides since it regulates many key soil processes, including water, air and solute movement, root growth and the activity of soil biota. Soil structure is dynamic, driven by external factors such as land management and climate and mediated by a wide range of biological agents and physical processes operating at strongly contrasting time‐scales, from seconds (e.g., tillage) to many decades (e.g., faunal activity and soil aggregation). In this respect, positive feedbacks in the soil–plant system may lead in the longer term to soil physical degradation or to the recovery of structurally poor soils. As far as we are aware, no existing soil‐crop model can account for such processes. In this paper, we describe a new soil‐crop model (USSF, Uppsala model of Soil Structure and Function) that accounts for the effects of soil structure dynamics on water and organic matter cycling at the soil profile scale. Soil structure dynamics are expressed as time‐varying physical (bulk density, porosity) and hydraulic properties (water retention, hydraulic conductivity) responding to the activity of biological agents (i.e., earthworms, plant roots) and physical processes (i.e., tillage, soil swell‐shrink) at seasonal to decadal time‐scales. In this first application of the model, we present the results of 30‐year scenario simulations that illustrate the potential role and importance of soil structure dynamics for the soil water balance, carbon storage in soil, root growth, and winter wheat yields on two soils (loam and clay) in the climate of central Sweden. A sensitivity analysis was also performed for these two scenarios using the Morris method of elementary effects, which revealed that the most sensitive parameters controlling soil structure dynamics in the USSF model are those determining aggregation induced by organic matter turnover and swell/shrink. We suggest that the USSF model is a promising new tool to investigate a wide range of processes and phenomena triggered by land use and climate change. Results from this study show that feedback in the soil‐crop system mediated by the dynamics of soil physical and hydraulic properties are potentially of central importance for long‐term predictions of soil water balance, crop production, and carbon sequestration under global change. [ABSTRACT FROM AUTHOR]

This study discusses the issues in increasing the reliability of buildings and structures on Type II loess-like collapsible soils through the construction of basement floors. This study also analyses the effectiveness of using pile foundation options for buildings with basement floors made from driven and bored piles up to 50 m long that cut through collapsible soil of 10–32 m. Results showed that foundations made of driven and augered piles are the most effective in terms of cost, labour intensiveness, and concrete consumption, whereas options using barrettes are the least effective. [ABSTRACT FROM AUTHOR]

By conducting a two-dimensional experimental study, this paper aims to enhance the understanding of the mechanism of sand convective motions in the vicinity of a wall subjected to long-term cyclic lateral loadings. The experimental tests were conducted in a rectangular sandbox with a transparent front-wall, through which the process of sand particle motions could be recorded by using a high-resolution digital camera. The images were processed with a high time-resolved PIV (Particle Image Velocimetry) system. Based on the experimental data, this work (1) presents the sand flow field in the convective zones; (2) provides means to describe the convection mechanism; (3) proposes the relationships between the loading conditions and dimensions of the region with intense sand movement; and (4) elaborates the similarity of the sand flow velocity structure within the sand convective zones. [ABSTRACT FROM AUTHOR]

Microbial communities in the active layer play a crucial role in the biogeochemical cycles of Antarctic pristine ecosystems. Here, 16S rRNA gene sequencing was used to investigate bacterial communities in active layer of five different geological sites related to the compositional variation of the geological bedrock, including Neogene volcanic or Cretaceous rocks and or marine sediments areas of distinct elevation. Local variations in the thickness of the active layer (50–80 cm) were observed on the Ulu Peninsula, James Ross Island, and the southwest coast of Vega Island, Antarctica during sampling in 2019. High bacterial diversity was detected in all sampling sites. Significant site effects on bacterial composition with increased Chloroflexota and decreased Flavobacteriaceae were only observed between the highest elevation Johnson Mesa 2 plateau and coastal areas. The overall effect of the depth was reflected by the increased of e.g., Cyanobacteria, Propionibacterium, Staphylococcus in the upper surface and Chloroflexota, Acidobacteriota, Actinomycetota at depths below 30 cm. The huge number of unassigned bacteria indicated a potential source of new bacterial species and their ecological role in this extreme environment. For the first time, we showed that the effect of depth on bacterial composition was more significant than the effect of geological bedrock from these previously unexplored regions. [ABSTRACT FROM AUTHOR]

Microorganisms play a fundamental role in sustainable agriculture, and their importance in common bean (Phaseolus vulgaris) cultivation cannot be underestimated. This review article aims to comprehensively explore the diverse roles of microorganisms in sustainable biofortified common bean cultivation. Biofortification refers to the process of increasing the nutrient content in crops, which helps combat deficiencies in iron, zinc, and vitamins in the human body. Biofortified beans have better agronomic characteristics and offer higher micronutrient content compared to conventional crops. We examine the contribution of various microbial communities in nitrogen fixation, soil structure improvement, nutrient recycling, and disease suppression. Understanding the interaction between beneficial microorganisms and biofortified common bean plants enables us to develop ecologically sound and sustainable approaches to optimize crop productivity and improve nutrition and livelihoods for millions of people worldwide while reducing the environmental impact of agricultural practices. [ABSTRACT FROM AUTHOR]

This study investigates the distribution, morphology, and properties of these soils, focusing on areas such as littoral plains, high hilly areas, and rift depression valleys. Black soils occur in the eastern Mediterranean with a limited distribution, and some of them meet the requirements for black soils according to the INBS (International Network of Black Soils), while others do not. Black soils can be categorized into three types based on their genesis and evolution: calcareous black soils (mainly raw rocky rendzina), hydromorphic black soils, and black soil on basalt. While black soils were found in various bioclimatic stages and parent materials, their presence was notably limited in certain areas, contrary to prior indications. A soil morphology analysis revealed distinct color variations and depths, influenced by the accumulation of organic matter for hydromorphic and calcareous black soils and basaltic parent material for black soils on basalt. A particle size analysis indicated texture variations from clay to loam, with no clear indication of illuviation. A chemical analysis showed alkaline pH levels, except in basalt-derived soils, which exhibited a slight acidity. Hydromorphic black soil is the most important in terms of expansion and agricultural use and is only found in limestone marl deposits and lakes in depressions emerging from Dead Sea rifts under conditions of saturation or poor drainage. These soils have a thick, dark moly horizon and a high organic matter content. [ABSTRACT FROM AUTHOR]

The evaluation of soil particle composition and salt dynamics is essential for promoting the sustainable development of oasis agriculture in arid regions under long-term mulched drip irrigation (MDI). In this study, we employed the space-for-time substitution method to investigate the long-term effects of MDI on soil particle composition and salinity. Additionally, seven fields, with MDI durations ranging from 0 to 16 years, were selected to represent the primary successional sequence though time in Northwest China. Soil samples were collected from three soil depths (0–30 cm, 30–60 cm, and 60–100 cm) and then analyzed in the laboratory for soil particle composition and salt content. Our findings demonstrated that influenced by the depth of mechanical cultivation and the maximum wetting front depth, the long-term application of MDI significantly altered both the structure of soil layers and the composition of soil particles after 8 years. Soil sand content and soil salinity gradually decreased, whereas the content of soil silt and clay increased with increasing MDI duration throughout 0–100 cm soil depth. Furthermore, the rates of soil desalination stabilized after 10 years of MDI application, with desalination levels exceeding 90% in the 0–100 cm soil layer. Additionally, the soil mass fractal dimension (Dm) exhibited an upward trend across 0–100 cm soil depth. The changes in soil particle composition indirectly influenced the variations in Dm and salt content. Our study demonstrated that long-term application of MDI effectively mitigated soil salinity, changed soil structure, and ultimately enhanced soil quality and cotton yield. [ABSTRACT FROM AUTHOR]

It is crucial to comprehend how fertilization and cultivation management alter the composition of dissolved organic carbon (DOC) and microbial communities to regulate the biogeochemical cycling of soil nutrients and mitigate adverse impacts on soil–water quality. Based on 15 years of long-term field trials conducted in purple soil on farmland with a slope of 15° in southwestern China, the following five treatments were examined: CK (no fertilizer was applied), T1 (NPK plus organic manure and downslope cultivation), T2 (NPK and downslope cultivation), T3 (1.5-fold NPK and downslope cultivation), and T4 (NPK and contour cultivation). Soil samples were obtained from summer maize at two soil depths (0–10 and 10–20 cm) and from rhizospheric soil, and the changes in the DOC content, UV–visible (UV–Vis) absorptivity, and phospholipid fatty acids (PLFAs) were assessed. Our results revealed a significant change in the DOC content following fertilization, especially in T1, as it was 136.0%, 179.4%, and 132.2% higher, respectively, than that in CK at the 0–10 and 10–20 cm depths and rhizospheric soil. Fertilization decreased the UV–Vis absorptivity variables of DOC (i.e., SUVA254, SUVA260, SUVA400, SUVA465, SUVA665, and C:C ratio) and raised the E4:E6 ratio (fulvic acid to humic acid in DOC), regardless of T2 and T3 at the 10–20 cm depth and in the rhizospheric soil compared with those in CK, respectively. Fertilization significantly increased the total PLFA content and selected microbial groups relative to CK. Among the treatments, T1 significantly increased the total PLFA content by 50.6%, 59.0%, and 46.2%, respectively, relative to CK, at the 0–10 and 10–20 cm depths and in the rhizospheric soil. The microbial community structure in contour cultivation (T4) was significantly greater than in downslope cultivation (T2). Random forest analysis (RFA) revealed that SOC and DOC were likely the primary variables for regulating the total PLFAs in the examined soil. Partial least squares path modeling (PLS-PM) further indicated that the DOC content and the ratio of E4:E6 among DOC compositions had greater effects on the soil microbial community structure in the examined soil. These observations suggested that long-term fertilization and cultivation management are effective approaches to regulating the soil microbial community structure by altering the composition of DOC in sloping farmland. [ABSTRACT FROM AUTHOR]

The rapid loss of global biodiversity can greatly affect the normal functioning of ecosystems. However, how biodiversity losses affect plant community structure and soil nutrients is unclear. We conducted a field experiment to examine the short‐ and long‐term effects of removing plant functional groups (Gramineae, Cyperaceae, legumes, and forbs) on the interrelationships among the species diversity, productivity, community structure, and soil nutrients in an alpine meadow ecosystem at Menyuan County, Qinghai Province. The variations in the species richness, above‐ and belowground biomass of the community gradually decreased over time. Species richness and productivity were positively correlated, and this correlation tended to be increasingly significant over time. Removal of the Cyperaceae, legumes, and other forbs resulted in fewer Gramineae species in the community. Soil total nitrogen, phosphorus, organic matter, and moisture contents increased significantly in the legume removal treatment. The removal of other forbs led to the lowest negative cohesion values, suggesting that this community may have difficulty recovering its previous equilibrium state within a short time. The effects of species removal on the ecosystem were likely influenced by the species structure and composition within the community. Changes in the number of Gramineae species indicated that they were more sensitive and less resistant to plant functional group removal. Legume removal may also indirectly cause distinct community responses through starvation and compensation effects. In summary, species loss at the community level led to extensive species niche shifts, which caused community resource redistribution and significant changes in community structure. [ABSTRACT FROM AUTHOR]