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Basalt is a major component of the lunar soil and crust. The frictional properties, and thus the potential for seismicity and associated hazards on basaltic faults are significantly influenced by particle size distribution and normal stress conditions. We conducted velocity-stepping and slide-hold-slide shear experiments on simulated basalt gouges at gouge particle sizes of 50–250 μm, and normal stresses of 5–30 MPa under wet/dry conditions with different gouge structures to investigate the frictional stability and healing of basaltic faults. We observe a transition from velocity-strengthening (a – b = 0.52) to velocity-weakening behavior (a – b = -0.0005) and an enhanced healing rate (from 0.0075 to 0.0044), as particle size decreases. Elevated normal stress is typically associated with reduced grain size, resulting in unstable slip behavior (a – b = -0.0006), though accompanied by a diminished healing rate (from 0.0062 to 0.0050). The presence of fluid contributes to stable slip behaviors and fault compaction. These observations contribute to a better understanding of the potential and nucleation mechanism of lunar seismicity within basaltic faults. Highlights Small grain size gouges facilitate fault instability and strength recovery in basaltic faults. High normal stress on basalt gouges assists grain crushing and weakens frictional strength recovery. Fluid enhances fault stability and fault compaction of basaltic faults at room temperature. Deeper crust with higher confining stress and smaller grains suggests higher seismic potential. [ABSTRACT FROM AUTHOR]

[Objective] To investigate the impact of intermittent rainfall on the amount and sorting characteristics of black soil splash erosion. Methods］ This study is based on artificial simulated rainfall experiments, with two rainfall intensities (40, 70 mm/h) designed, each with 5 rainfall events, to analyze the splashing erosion amount and particle size distribution characteristics of black soil under different rainfall conditions. Results］ Under two different rainfall intensities, there is a dynamic development process of alternating strength between "no crust weak crust strong crust weak crust new crust" in the soil surface layer of different rainfall sites. Under two different rainfall intensities, the maximum values of splashed aggregate MWD and GMT) appeared in the fourth rainfall, and the minimum values appeared in the first rainfall. The agglomerates with a particle size of 5 〜2 mm did not migrate in each rainfall, and the splashed agglomerates were mainly composed of particles with a size of 2〜().25 mm, accounting for 36.49% 〜58.61 % and 49.1()% 〜 60.09% of the splashed erosion amounts of the two rainfall intensities, respectively. The erosion amount of the five rainfall events showed a trend of first increasing and then decreasing with the decrease of particle size, while the mass percentage with particle size <1 ().053 mm showed a trend of first decreasing and then increasing with the increase of intermittent frequency. The mass percentage with particle size ().053 mm all showed the minimum value in the third rainfall event, which was 1&21% and 17.63%，respectively. Conclusion] Rainfall can lead to the formation of soil crust, and the thickness of soil crust shows dynamic changes with the increase of rainfall frequency. Tn the third rainfall, the soil crust thickness is the highest, and at this time, the splash erosion amount has the minimum value, mainly greater than ().053 mm. The research results provide reference for the study of soil water erosion mechanism in the black soil area of Northeast China. [ABSTRACT FROM AUTHOR]

Inoculation of cyanobacteria has been studied as a valuable approach to promote soil stabilization and fertilization and counteract the erosion of marginal soils. One of the results of the inoculation of cyanobacteria is the formation of biological soil crusts, or biocrusts, which are complex soil communities playing a pivotal role in providing essential ecosystem services in drylands. While numerous studies have addressed the effects of different biocrust attributes on ecosystem functions, few studies have focused on the distribution of biocrust successional stages in the soil and their link with soil fertility properties. In this work, we investigated how the distribution of biocrust types (cyano-crust; cyano/moss crust, and moss crust) is related to soil nutrient status. We evaluated phototrophic abundance, exopolysaccharide production, and nutrient content in distinct biocrust types in an experimental area in the Hopq Desert, China, where their occurrence had been induced by cyanobacteria inoculation. In addition, we investigated the correlation between these variables. Photosynthetic pigment content, total carbohydrates, exopolysaccharides, organic C, and total N increased during the biocrust maturation stages. We found significant correlations between the levels of organic C, total carbohydrates, and total N with the abundance of diazotrophic cyanobacteria. Organic N was greater in the cyano/moss crust, while available P accumulated mainly in the cyano-crust. The three biocrust types are essential to each other as each represents a stage in which distinct nutrients are stored. This study complements previous studies by offering a more comprehensive view of how phototrophic variability in the distribution of biocrusts dominated by cyanobacteria or by mosses is closely interconnected with nutrient content and biocrust development. [ABSTRACT FROM AUTHOR]

Suction bucket jackets have been used as foundations for offshore wind turbines in intermediate water depths where layered soil stratigraphies are often encountered. Although suction installation in layered soils has been studied, experimental data on the in-service response is scarce. During installation in stratigraphies containing a low permeability layer underlain by a high permeability layer, suction is transferred to the underlying layer when the pressure at the lid invert is sufficient to uplift the low permeability plug. This suction-transfer mechanism also affects the in-service response, albeit the load-sharing mechanism is not well understood. This paper presents data from centrifuge tests of suction buckets subjected to constant amplitude and varying amplitude cyclic vertical loading in two stratigraphies—a sand with an overlying clay layer and in a sand with a sandwiched clay layer. These experiments show that tensile stresses exceeding the vented tensile resistance can be withstood without significant uplift of the bucket in both stratigraphies, even under a zero mean stress. Plug uplift was shown to have an important effect on the amount of stress transferred to the skirts, with the load-sharing mechanism depending on the stratigraphy. Additionally, the load-sharing mechanism and the bucket in-service resistance was shown to depend on the effectiveness of the clay in sealing the soil plug within the bucket, with a more effective seal resulting in higher tensile resistance and therefore better performance. A limiting loading condition was not identified in the sand with a sandwiched clay layer, with the data indicating that the suction pressure to cause plug uplift during cyclic loading may be much higher than during suction installation. [ABSTRACT FROM AUTHOR]

Soil crust is of high concern in soybean cultivation due to its adverse impact on seedling emergence. Despite the necessity of soybean varieties with stable seedling emergence against soil surface crust, genotypic variation of this trait has not been well understood because there have been no general protocols widely applicable to a set of accessions. The major constraint in conducting such experiments is the difficulty in reproducing soil crust with uniform hardness for each set of experiments. In this study, a simple method that can evaluate the seedling emergence under the conditions of uniform hardness of soil crust using gypsum mixed soil was developed and tested for 82 soybean accessions. Among the tested accessions, five genotypes with high seedling emergence under soil crust conditions were identified. [ABSTRACT FROM AUTHOR]

Gobi's (gravel deserts) are one of the largest dust sources in northern China. Previous studies indicated that sand transport processes above the surface differed between Gobi and sand surfaces. However, the sand transport rate and related dust emission processes above Gobi (gravel) surfaces are still poorly understood. In this field study, we quantified this transport to provide important support for parameterizing Aeolian sediment transport models and clarifying the relationship between dust emission and transport. Threshold wind velocity can reach 0.38 ± 0.04 (mean ± SD) m s−1 above Gobi surfaces. Compared to the most commonly used sand‐transport models, we found that the Lettau and Lettau sediment transport model can be used to calculate horizontal sediment transport above a Gobi surface. The relationship between the vertical sediment transport (Fs) and shear velocity could be expressed using a power function. Although the horizontal sand transport and vertical flux (Q and Fs, respectively) above Gobi surfaces can be expressed similarly to previous results (i.e., using similar equation forms), the equation coefficients were much larger for the Gobi surface than for a shifting sand surface; that is, sediment transport was higher above the Gobi surface. This difference resulted from the larger sand transport rate and saltation height above the Gobi surface, and the larger transport and higher saltation height were related to the larger sand transport height and higher content of coarse sand transported above the Gobi surface. Plain Language Summary: Sediment transport by the wind is a major erosion process in the world's arid and semiarid regions but also occurs on other planets. This transport causes the formation and evolution of sand dunes and produces dust storms. Therefore, it is important to accurately quantify Aeolian sediment transport to support the design of measures to prevent or mitigate desertification and to predict dust storm occurrence and severity. Previous studies have shown that sediment transport above gravel (Gobi) surfaces differs from transport above a mobile sand surface. However, the relationships between sand transport and dust emission above a Gobi surface are poorly understood. In this study, we measured sediment transport by the wind above Gobi surfaces in the field, and found higher sand transport rates and higher saltation (hopping of particles) heights above the Gobi surfaces than above a mobile sand surface. The change of the transport rate with height could be expressed as a Gaussian peak function. The observed sediment transport results from the nature of the gravel surface and soil crusts, which cause higher saltation above a Gobi surface than above mobile sand. We parameterized the coefficient values for previous transport models, which will support efforts to improve sand transport models. Key Points: Horizontal sediment transport followed the Lettau and Lettau's (1978) equationThe saltation height above the Gobi surface is higher than the sand surfaceCoarse and fine materials were both transported above the Gobi surface [ABSTRACT FROM AUTHOR]

The terrestrial environment generally serves as an important carbon pool. This study mainly assessed the properties and carbon storage capabilities of soils from different urban land uses. Soil samples from roads/highways, parks, institutional areas, and constructed wetlands were collected to assess the effects of soil sealing on the characteristics and carbon content of urban soils. Soil sealing and compaction greatly influenced urban soil properties by altering the mass-balance, thereby resulting in a disproportionate amount of inflow and outflow of compounds in the soil strata. Using the Walkley-Black and loss-on-ignition (LOI) methods of soil organic carbon (SOC) analysis demonstrated that LOI-based analysis yielded up to 26 times higher SOC values than the wet-oxidation method due to the high weight losses prompted by the volatilization of hygroscopic and structural water and thermal decomposition of carbonate-containing minerals. Further analyses indicated that open soils contain 5% to 78% higher percentage of organic carbon as compared with their sealed counterparts and top soil layers tend to have higher amounts of SOC due to the continuous deposition of carbon-containing compounds from external sources. Generally, the results of this inquiry can serve as a baseline for formulating strategies to augment pedologic carbon stocks in urban environments. [ABSTRACT FROM AUTHOR]

Wind erosion and dust emission from drylands have large consequences for ecosystem function and human health. Wind erosion is naturally reduced by soil crusting and sheltering by non‐erodible roughness elements such as plants. Land uses that reduce surface roughness and disturb the soil surface can dramatically increase dust emission. Extraction of oil and gas is a common and growing land use in the western United States (US) that removes vegetation and other roughness elements for construction of well pads and unpaved access roads, resulting in thousands of small (1–4 ha), discrete patches of unprotected soil. Here, we use a satellite albedo‐based model to assess the effect of oil/gas activity on surface roughness in the Uinta‐Piceance Basin, an area of the Upper Colorado River Basin (UCRB) with dense oil and natural gas development and modelled how the change in surface roughness could impact aeolian sediment flux and dust emission. We also investigated how regional drought influences the response of surface roughness to well pads and access roads. Oil/gas activity reduced surface roughness and increased modelled aeolian sediment flux at the landscape scale across much of the study region, resulting in a modest increase of 10 139 kg of dust per year, which is small relative to dust loads from a single regional dust event observed in the region, but downwind impact could be significant. The magnitude of surface roughness reductions by oil/gas activity was generally consistent among land cover types. However, in parts of the basin that had high cover of annual forbs and grasses, oil/gas activity was associated with larger surface roughness and smaller potential dust emission. Drought decreased surface roughness across disturbed and undisturbed sites, but there was no interactive effect of oil/gas activity and drought on surface roughness. These results suggest that oil/gas activity may increase sediment fluxes and likely contributes to dust emission from landscapes in the UCRB. Understanding how drought and land use change contribute to dust emissions will benefit mitigation of undesirable impacts of wind erosion and dust transport. [ABSTRACT FROM AUTHOR]

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Lateral spreading has historically caused extensive pile failure in liquefaction‐prone areas during strong earthquakes. A critical design scenario involves piles embedded in lateral spreading ground composed of a nonliquefied soil crust overlying a liquefied layer; it is critical because both layers can exert loads on the piles. Different thicknesses of the liquefied soil and the upper nonliquefied crust may engender different pile response patterns. Accordingly, to investigate factors influencing the lateral responses of a single pile embedded in liquefied ground with a nonliquefied crust, we conduct parametric analyses. The effects of liquefied and nonliquefied soil thicknesses are analyzed first, followed by those of pile‐head rotational restraint, pile diameter, and lateral spreading displacement. We observe two main pile response patterns for various liquefied soil thicknesses. The ground can be categorized into thin or thick liquefied ground depending on whether its liquefied soil thickness is less or greater than a critical value, namely, critical liquefied soil thickness; this critical thickness is dependent on the pile‐head rotational restraint, pile diameter, and lateral spreading displacement. The difference in the patterns stems from the varying roles of the upper nonliquefied soil layer during lateral spreading. For the thin liquefied ground, the nonliquefied layer contributes to adding lateral spreading force; therefore, the displacement, moment, and shear force responses of the pile increase with the nonliquefied soil thickness. However, for the thick liquefied ground, the nonliquefied layer provides resistance to lateral spreading; therefore, the maximum displacement, moment, and shear force of the pile initially decreases and then gradually increases with the nonliquefied soil thickness. [ABSTRACT FROM AUTHOR]

In order to explore the effects of two plants on the spatial distribution and nutrient distribution of crusts in different directions and distances after 30 years of aerial seeding, as well as the relationship between crust thickness and nutrient content, this paper takes the aerial seeding afforestation area in the northeastern margin of Tengger Desert as the research area, and the crusts under the plants of Hedysarum scoparium and Calligonum mongolicum as the research objects. The distribution of crust thickness and nutrients was analyzed, and the relationship between them was constructed. The thickness of the crust of H. scoparium and C. mongolicum was the largest in the southeast direction and the smallest in the northwest direction. With increasing distance from the plant, it shows a significant decreasing trend. The crust thickness of H. scoparium was higher than that of C. mongolicum. The nutrient indexes in the southeast direction of the crust of H. scoparium and C. mongolicum were significantly higher than those in the northwest direction; With the increase of the distance from the root of the plant, the nutrient content showed a significant decreasing trend. The contents of organic matter and available nitrogen in the crust of C. mongolicum were higher than those of H. scoparium, and the contents of available potassium and available phosphorus were lower than those of H. scoparium. The trend of nutrient enrichment rate of the crusts of the two plants was consistent with the trend of nutrient distribution. There was a significant positive correlation between the crust thickness and nutrients in the four directions under C. mongolicum. There was a significant positive correlation between the crust thickness and nutrients in the southwest direction under H. scoparium. The changes of available nitrogen, available phosphorus, available potassium and organic matter content in the crust under H. scoparium can explain 52.5% of the change of its thickness. The changes of available nitrogen, available phosphorus, available potassium and organic matter content in the crust under C. mongolicum can explain 78.5% of the change of its thickness. After 30 years of aerial seeding in Tengger Desert, the thickness and nutrients of the crust in the southeast direction of H. scoparium and C. mongolicum were significantly higher than those in the northwest direction and showed a decreasing trend with the increase of distance from the root of the plant. There was a positive correlation between crust nutrient and thickness. [ABSTRACT FROM AUTHOR]

Cyanobacterial taxonomy is entering the genomic era, but only a few taxonomic studies have employed population genomics, which provides a framework and a multitude of tools to understand species boundaries. Phylogenomic and population genomic analyses previously suggested that several cryptic lineages emerged within the genus Laspinema. Here, we apply population genomics to define boundaries between these lineages and propose two new cryptic species, Laspinema olomoucense and L. palackyanum. Moreover, we sampled soil and puddles across Central Europe and sequenced the 16S rRNA gene and 16S‐23S ITS region of the isolated Laspinema strains. Together with database mining of 16S rRNA gene sequences, we determined that the genus Laspinema has a cosmopolitan distribution and inhabits a wide variety of habitats, including freshwater, saline water, mangroves, soil crusts, soils, puddles, and the human body. [ABSTRACT FROM AUTHOR]

Soils are threatened both in Europe and worldwide, predominantly because of human activities (e.g., unsustainable management practices in the agricultural and forestry sectors, soil contamination from the industries and soil sealing due to urbanization and building of infrastructures). Soil degradation and loss come at a substantial cost and have many repercussions on other features of the environment, such as landscapes and ecosystems. All the above prompts the question of what EU law has done to manage and rectify the situation. After the issues encountered in the context of the Proposal for a Soil Framework Directive in the past, the Green Deal and the Soil Strategy seemed to infuse new energy into the soil policy agenda and made clear that the Commission was very much ready for an ambitious step forward, in the form of a Soil Directive. However, while the proposed Directive covers important aspects of soil protection and remediation, it also falls short on several counts. [ABSTRACT FROM AUTHOR]

This study focused on polyphasic evaluation of four psychrophilic Pseudanabaena strains collected from extreme environments characterized by freezing temperatures. The strains were isolated from hydroterrestrial and terrestrial ecosystems in Petuniabukta Bay (Billefjorden, Svalbard), growing as icy microbial soil crusts. In addition to their unique ecology, the phylogenetic analyses of 16S rRNA revealed that the strains form a monophyletic clade within the Pseudanabaena sensu stricto cluster; this clade was unambiguously separated from the other Pseudanabaena infrageneric units, showing <98.5% 16S rRNA sequence identity with the other Pseudanabaena strains available in GenBank and possessing a unique and different D1 ITS region. Polyphasic evaluation of these four strains led to the description of the new species Pseudanabaena pruinosa sp. nov. which can be morphologically distinguished by light microscopy by several unique apomorphic traits not previously detected in Pseudanabaena. These traits include: production of widened, anastomotic branched sheaths enveloping several trichomes into a filament, heteropolar filaments with long trichomes with more than 20 cells, richly pseudobranched filaments forming tree-like structures, production of both polar and central aerotopes, and ability to produce swollen cells and to undergo irregular cell division. The characters observed for Pseudanabaena pruinosa, never reported for other species of Pseudanabaena, substantially widen the taxonomic concept of this genus. Therefore, the description of Pseudanabaena pruinosa sp. nov. with its unique ecology and distinct phylogenetic position and morphological features, is a significant addition to cyanobacteriology and represents a starting point for further research into the evolution of the genus Pseudanabaena. The new combination Pseudanabaena gygaxiana (Casamatta & Johansen) Aleksovski, Krstić & Strunecký is proposed based on16S rRNA, supported by its shared phenotypic traits and similar ecology to Pseudanabaena pruinosa. [ABSTRACT FROM AUTHOR]

Collapsing erosion is a unique phenomenon commonly observed on the granite residue hillslopes in the tropical and subtropical regions of southern China, characterized by its abrupt occurrence and significant erosion volumes. However, the impacts of soil crust conditions on the erosion of colluvial deposits with granite residual soils have only been studied to a limited extent. To address this issue, this study investigates the impacts of three soil crust conditions (i.e., without crust, 10-minute crust, and 20-minute crust) on gully morphology, rainfall infiltration, and runoff and sediment yield during slope erosion of colluvial deposits with granite residues (classified as Acrisols) in Yudu County, Ganzhou City, Jiangxi Province, China, using simulated rainfall tests and photographic methods. The results showed that as the strength of the soil crust increased, the capacity of moisture infiltration and the width and depth of the gully as well as the sediment concentration and yield ratio decreased; at the same time, the runoff ratio increased. The sediment yield in the without-crust test was found to be 1.24 and 1.43 times higher than that observed in the 10-minute crust and 20-minute crust tests, respectively. These results indicate that soil crusts can effectively prevent slope erosion and moisture infiltration, while providing valuable insights for the management of soil erosion in natural environments. [ABSTRACT FROM AUTHOR]

The increase in rainfall intensity caused by climate change, combined with high levels of urban soil sealing and the limited capacity of drainage systems, is significantly increasing flooding risk. Integrated stormwater management is a key factor in dealing with the consequences of climate change by mitigating flood risk based on nature-based solutions. An experimental site was designed to assess the hydrological response of vegetated swales depending on different catchment surfaces, and to evaluate the impact of spatial variability of the hydraulic conductivity (K). A hydrological model was developed on EPA SWMM and calibrated based on measured data in two experimental swales with different active surfaces (N6—50 m2 and N11—100 m2). The model validation was assessed with NSE scores higher than 0.7. The simulations considered various factors, such as the water level in the swales, the actual rainfall, the evapotranspiration, the swale geometry, the catchment area (Sa), and the hydraulic conductivities of the natural silty soil, to assess, for the heaviest rainfall event, the best swale morphological characteristics. The study examined the combined impact of K (8) and Sa (6) on swale storage capacity, designed with a 250 mm depth. The simulations showed that the 250 mm overflow limit was exceeded for N10 (90 m2) when K ≤ 2 × 10−6 m/s, and for N11 (100 m2) when K ≤ 4 × 10−6 m/s. These results provide valuable information on the optimal storage capacity based on the swales' geometrical and physical properties. [ABSTRACT FROM AUTHOR]

In a context of increasing urbanization, with strong soil sealing, and with an increase in extreme weather events, the management of rainwater in urban areas is becoming a major issue. In order to improve water resource management and to prevent urban floods, more and more cities are considering or already implementing water infiltration systems. Infiltration of water is not possible anywhere due to natural and/or anthropic reasons. In this frame, the intrinsic infiltration capacity of the subsurface is one key natural parameter. Global maps are needed to build territorial strategies. In France, a lot of studies are available but a national methodological framework for mapping this index does not exist. In this paper, we analyse various studies carried out in France for such mapping and compare the methods with examples in other countries. Most of the French studies combine a Multi-Criteria Analysis (MCA) and a Geographic Information System (GIS) spatial analysis. The criteria include geological, hydrogeological and geomorphological parameters. The PHOEBUS method developed on Rennes Metropolis seems the most relevant and replicable one to provide a common framework at French scale. It takes into account 7 criteria, including rock/soil permeability, topographic slope and thickness of the unsaturated zone. The obtained maps may be used as such, modified by integrating sealed surfaces or crossed with other criteria linked to the urban environment (e.g. sealed surfaces, soil pollution, heat islands). They provide a decision support tool for urban planning. In particular, they are useful to improve rainwater management, but also in the elaboration of desealing or renaturation strategies. It seems essential to act in concertation with local stakeholders to identify their needs and the specificities of the territory. [ABSTRACT FROM AUTHOR]

The European Copernicus Land Monitoring Service (CLMS) has been producing datasets on imperviousness every 3 years since 2006. However, for 2018, the input for the production of the imperviousness dataset was switched from mixed inputs to the Sentinel constellation. While this led to an improvement in the spatial detail from 20 m to 10 m, this also resulted in a break in the time series as the 2018 update was not comparable to the previous reference years. In addition, the European CLMS has been producing a new dataset from 2018 onward entitled CLC+ Backbone, which also includes a sealed area thematic class. When comparing both datasets with sampled reference data, it appears that the imperviousness dataset substantially underestimates sealed areas at the European level. However, the CLC+ dataset is only available from 2018 and currently does not include any change layer. To address these issues, a harmonized continental soil sealing combined dataset for Europe was produced for the entire observation period. This new dataset has been validated to be the best current dataset for monitoring soil sealing as a direct input for European policies with an estimated total sealed area of 175,664 km2 over Europe and an increase in sealed areas of 1297 km2 or 0.7% between 2015 and 2018, which is comparable to previous time periods. Finally, recommendations for future updates and the validation of imperviousness degree geospatial products are given. [ABSTRACT FROM AUTHOR]

This document serves as a closure to a previous article on infiltration model parameters for sandy soils. It addresses points raised by discussers and compares the data to previous work. The writers agree with the discussers' assessment that soil placed in test plots may not directly apply to natural soils, and they acknowledge the importance of ground cover in infiltration and runoff. Additional tests on stone-covered soils are included to illustrate the impact of ground cover. The document also compares findings to previous studies, showing close agreement. The document provides data on the effective hydraulic conductivity of different soil types, categorized as "Bare (scraped)" or "Low," along with corresponding values. The authors acknowledge the study's limitations and the importance of soil data in hydrologic modeling, emphasizing the need for improved methods of model parameterization. [Extracted from the article]

Consecutive high-temperature days, a phenomenon known as heatwaves, are becoming more frequent and intense due to anthro- pogenic climate change. Padua City, characterized by significant urban soil sealing, is particularly vulnerable to these changes and the exacerbation of Urban Heat Island effects. This study integrates Urban Digital Twin technology and Internet of Things concepts within a three-dimensional modelling environment to develop a Nature-Based Solutions scenario simulation tool. This tool is designed to address climate-manmade problems in Padua City. Using sensor-derived air temperature and relative humidity data, our approach provides detailed micro-climate information to identify heat-prone areas in Padua City. According to this in- formation, the first pilot project test of scenario development was selected to assess how best to achieve a cooling effect through the use of green-blue infrastructure in order to combat the heat hazard in Padua City. Furthermore, this study addresses the urgency of developing Nature-Based Solutions in Padua City's planning to reduce the heat effect during heatwaves. [ABSTRACT FROM AUTHOR]

The shrub and patch size of moss crusts can significantly affect plant and soil nutrients. The effects and relationships of shrubs and moss crusts on soil multifunctionality are unclear. This study aimed to understand the spatial heterogeneity of soil multifunctionality in moss crust patches and shrubs. Soil organic carbon, nutrient, and enzyme activities under moss crust patches were measured. Interestingly, the soil polyphenol oxidase (PPO) and peroxidase (POD) activities, carbon‐related soil multifunctionality index (C‐SMF), nitrogen‐related soil multifunctionality index (N‐SMF), phosphorus‐related soil multifunctionality index (P‐SMF), and soil multifunctionality index (SMF) increased with increasing patch size in moss crusts. The patch size of moss crusts had no significant effect on the C‐SMF, N‐SMF, P‐SMF, and SMF under the shrub. The soil C‐SMF, N‐SMF, P‐SMF, and SMF under shrubs were significantly higher than that in exposed areas (EAs). The soil PPO, POD, N‐SMF, P‐SMF, and SMF under dead shrubs were significantly higher than those under living shrubs and in EAs. Evaluation and composition analysis of C‐SMF, N‐SMF, and P‐SMF indicated that moss crust promotes the increase of P‐SMF, and that shrub promotes the increase of C‐SMF and N‐SMF. Moss crust patches mainly affected phosphorus functionality, increasing phosphorus cycling. Shrub promotes soil carbon and nitrogen functionality. This study elucidates the effect of moss crust patch size on soil multifunctionality influenced by shrub growth in desert ecosystems and provides further new insights into the soil processes and functions. Results are beneficial for the comprehensive utilization of fertile islands and its enhancement of beneficial ecological functions, such as maintaining soil nutrition, quality, health, and vegetation restoration, and lay a foundation for future research on nutrient absorption and utilization between mosses and shrubs. Core Ideas: The patch size effect of moss crusts is a positive in soil multifunctionality and is influenced by microhabitats.Moss crust patches mainly affected phosphorus functionality, increasing phosphorus cycling.Shrub patches mainly affected soil carbon and nitrogen functionality. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are essential raw materials for modern industries but mining them has caused severe environmental issues, particularly the recovery of heavy REEs (HREEs) from ion-adsorption deposits (IADs). Very recently, an emerging technology, electrokinetic mining (EKM), has been proposed for the green and efficient recovery of REEs from IADs. However, the conduction mechanism of the weathering crust soil, which is also a prerequisite for EKM, remains unclear, making the EKM process unpredictable. Here, we systematically investigated the conductivity of weathering crust soil in the presence of light REEs (LREEs, i.e., La3+ and Sm3+) and HREEs (Er3+ and Y3+), respectively. Results suggested that the voltage was dynamically and spatially redistributed by the movement of REEs and water during EKM, and the conventional assumption of the linear distribution of voltage leads to an inaccurate description of soil voltage. We proposed an improved Archie's equation by coupling the mechanisms of liquid phase and solid-liquid interface conduction, which can predict soil conductivity more precisely. Moreover, the extended Archie's equation is able to recalculate the voltage distribution at distinct times and spaces well during EKM. More importantly, the water content in field-scale weathered-crust soils can be retrieved by the newly proposed Archie's equation, which helps optimize the leaching wells and improve the recovery rate of REE. This study focuses on the conduction mechanism of weathering crust soil, which provides a theoretical basis for better use of the EKM technology and promotes mining efficiency fundamentally. [ABSTRACT FROM AUTHOR]

Microscopic green algae are severely understudied compared to their plant relatives. Algae from desert soil crusts are of special interest because they may have unique adaptations to the harsh arid habitats. Algae inhabiting gypsum substrates are especially poorly understood, and our study was the first to investigate the diversity of green algae in the gypsum soil crusts of White Sands National Park (WSNP). In addition, we characterized new algal isolates from another desert area, the Organ Mountains--Desert Peaks National Monument (OMDP), which had non-gypsiferous soils. We used a combination of light microscopy and DNA barcoding (using the rbcL and 18S genes) to classify the newly obtained algal strains. We also conducted an experiment to determine whether strain isolation could be aided by the addition of anhydrite to the growth media. We isolated 24 green algal strains, spanning 12 genera in 2 classes. There was no overlap in taxa between localities or samples. The most common taxon in the WSNP samples was Bracteacoccus minor, a common species with a near-worldwide distribution. The WSNP samples also harbored 2 genetically unique algae from the family Oocystaceae, which may represent species or genera new to science. The OMDP samples were overall more diverse than the WSNP material and contained species belonging to common soil-dwelling genera. Our growth experiment did not support our hypothesis; the growth of colonies was significantly inhibited by the addition of anhydrite to culture media, especially (and counterintuitively) in the WSNP sample. Overall, our study shows that there may be previously unknown algal species in the soil crusts of New Mexico, especially in the soils of WSNP. Additional sampling and isolation will likely reveal more algal diversity in both localities and will further enrich our knowledge of the New Mexico microflora, which to date remains largely unknown. [ABSTRACT FROM AUTHOR]

Biological soil crusts represent a rich habitat for diverse and complex eukaryotic microbial communities. A unique but extremely common habitat is the urban sidewalk and its cracks that collect detritus. While these habitats are ubiquitous across the globe, little to no work has been conducted to characterize protists found there. Amoeboid protists are major predators of bacteria and other microbial eukaryotes in these microhabitats and therefore play a substantial ecological role. From sidewalk crack soil crusts, we have isolated three naked amoebae with finely tapered subpseudopodia, and a simple life cycle consisting of a trophic amoeba and a cyst stage. Using a holistic approach including light, electron, and fluorescence microscopy as well as phylogenetics using the ribosomal small subunit rRNA gene and phylogenomics using 230 nuclear genes, we find that these amoeboid organisms fail to match any previously described eukaryote genus. However, we determined the amoebae belong to the amoebozoan lineage Variosea based on phylogenetics. The molecular analyses place our isolates in two novel genera forming a grade at the base of the variosean group Protosteliida. These three novel varioseans among two novel genera and species are herein named "Kanabo kenzan" and "Parakanabo toge." [ABSTRACT FROM AUTHOR]

The inoculation of cyanobacteria for enriching soil nutrients and forming biological soil crusts (BSCs) is considered an effective means to restore degraded soil. However, there are limited studies on the application of co-inoculation of fungi and cyanobacteria for degraded soil remediation. In this study, a high exopolysaccharide-secreting fungi Zh2 was isolated from lichen BSCs in Hobq Desert, and co-inoculated with a cyanobacterial strain identified as Phormidium tenue in different proportions to form BSCs on sand during a 35 days incubation period. Results revealed significant differences in crust biomass and soil properties among crusts with different cyanobacterial/fungal inoculation ratios. Microbial biomass, soil nutrient content and enzyme activities in crusts coinoculated with cyanobacteria and fungi were higher than those inoculated with cyanobacteria and fungi alone. The inoculation of cyanobacteria contributed to the fulvic-like accumulation, and the inoculated fungi significantly increased the humic-like content and soil humification. Redundancy analysis showed that the inoculation of cyanobacteria was positively correlated with the activities of urease and phosphatase, and the content of fulvic-like. Meanwhile, the inoculation of fungi was positively correlated with the contents of total carbon, total nitrogen and humic-like, the activities of catalase and sucrase. Cyanobacteria and fungi play distinct roles in improving soil fertility and accumulating dissolved organic matter. This study provides new insights into the effects of cyanobacteria and fungi inoculations on the formation and development of cyanobacterialfungus complex crusts, offering a novel method for accelerating induced crust formation on the surface of sand. [ABSTRACT FROM AUTHOR]

Seepage control is critically essential for dams, slopes, and the stability of many engineering structures, developing over many years using different methods. This study presents a novel approach for seepage control using the photopolymerization technique to form an impermeable crust at the soil surface. Effects of exposure duration (5, 10, 15, and 30 min) and light intensities (140, 550, 710, and 1000 W/m2) on the seepage control effectiveness of four different sand soils were investigated by using the photopolymerization technique. The three-point bending, permeability and acid rain simulation tests were performed to illustrate the effect of photopolymerization on the seepage control of sand soils. Furthermore, the influence of photopolymerization on the microstructure of soils was examined with the aid of SEM analysis. The results indicated that the photopolymerization technique could improve the crust strength, acid rain durability, and permeability of sand soils. The crusts at the surface layer of soils were formed after the photopolymer was applied to the sand surface and then exposed to UV light. These crusts of different soils have bending strengths and thicknesses in the range of 34.57 and 68.07 MPa, 2.13 and 6.18 mm, respectively. The increase in exposure duration and light intensity, resulted in the gradual increment of soil crust thickness. On the other hand, the increase in light intensities have more effective on the crust thickness. The formed soil crust has been provided an impermeable surface that prevents the weight loose from the surface of the soil under acid rain conditions. The SEM analysis indicated that the photopolymerized gels were homogeneously distributed between the grains in all samples, although the grain distribution of soils were different. Since the photopolymerization method has a short treatment duration and is easier to apply on the sand surface, the occurrence of the crust at the soil surface by this technique may open a new and improvable path for seepage control. The obtained results showed that the photopolymerization method is promising for repairing, restoring, and strengthening the construction materials in different engineering areas, as well as seepage control. [ABSTRACT FROM AUTHOR]

Biological soil crusts (BSCs) play an important role in soil development and ecological function, and it is more important for quantitatively analyzing the processes and trends of BSCs to identify the advantages and disadvantages of BSCs research for the development and application of BSCs theory. Bibliometric analysis of 2,186 BSCs literatures from Web of Science showed an exponential growth trend, as China and the United States as the top 2 in terms of publication volume. High quality publications are mainly from European and American countries, such as the United States, Germany and Spain. The top 3 publishers are Journal of Arid Environments, Soil Biology & Biochemistry and Plant and Soil, and disciplines include ecology, environmental science, and soil science, etc.. Research institutions mainly affiliate to the Chinese Academy of Sciences, United States Department of the Interior, United States Geological Survey, Hebrew University of Jerusalem, Consejo Superior de Investigaciones Cientificas, and Universidad Rey Juan Carlos. Authors mainly come from United States, Israel, Spain and China. Funds are mainly from the National Natural Science Foundation of China, Spanish Government, Chinese Academy of Sciences, and National Science Foundation of the United States. Biological soil crusts (biocrusts, cyanobacteria, lichens, moss crusts, bryophytes), drylands, climate change, photosynthesis and desert are high-frequency keywords. Future research will focus on the driving mechanisms of BSCs on global biogeochemical cycles, maintaining global biodiversity on important ecological processes, global C, N, and P cycles. The impact on biological invasion, sandstorms, and water balance, multifunctional and reciprocal mechanisms for maintaining the stability of desert and sandy ecosystems, and impact on the formulation of management policies for arid ecosystems, corresponding to global climate change, and the estimation of regional, local, and microscale distribution of BSCs based on machine deep learning modeling gradually focus on. The ecosystem service functions of BSCs, the soil and water conservation and soil stability mediated by BSCs in arid and semi-arid regions, and the excavation of stress resistant genes for BSCs will be emphasized. [ABSTRACT FROM AUTHOR]

The changes of soil moisture, salinity, and nutrients by halophyte colonization in high-salinity environment profoundly affect the assembly and structure of microbial communities. However, salt marshes in arid region have received little attention. This study was conducted in Lianhuachi Lake, a typical inland salt marsh wetland in China, to determine the physicochemical characteristics of salt crusts in [Kalidium cuspidatum (Ung.-Sternb.) Grub.] colonization areas and bulk soil, respectively, and to analyze the microbial community structure of salt crusts by high-throughput sequencing. Kalidium cuspidatum colonization significantly decreased total salinity, soil water content, and water-soluble ions of salt crusts and increased total carbon, total nitrogen, and total phosphorus content. At the same time, changes in physicochemical properties caused by Kalidium cuspidatum colonization affect the ecological processes of bacterial, fungal, and archaeal community assemblies in salt crusts. In addition, cross-kingdom network analysis showed that Kalidium cuspidatum colonization increased the complexity and stability of microbial networks in salt crust soils. Functional projections further showed that bacterial diversity had a potential driving effect on the nitrogen cycle function of salt crust. Our study further demonstrated the different ecological strategies of microorganisms for halophyte colonization in extreme environments and contributed to the understanding of restoration and management of salt marsh wetlands in arid region. [ABSTRACT FROM AUTHOR]

This study seeks to contribute to the definition of a "no net land take" policy by 2050 for Portugal's second-largest metropolitan region (AMP, Porto Metropolitan Area) while sensitising those involved in regional and local planning to the European target. Based on an assessment of land use changes in AMP and its municipalities during 2007–2018, soil sealing levels in 2018 and population evolution, the study quantifies the processes that may impart achievement of the 2050 objective and identifies the regional drivers of net land take, to support the definition of both interventions to decrease land take and soil sealing and related targets. The main contribution of the research is the exploration of new indicators in terms of soil sealing and population data to identify the potential for implementing interventions proposed by the EU Soil Strategy that do not jeopardise the maintenance of biodiversity in urban areas. The land take rate in the AMP was the highest among mainland Portugal regions. Its main drivers were the development of transport networks, industrial and commercial units and dispersed housing. The reuse and re-naturalisation of artificial land have seen little use in the region. Accordingly, the daily net land taken in the AMP (0.59 ha/day) still needs to decrease until 2050. While artificial land increased across the AMP, most of its municipalities lost population. To reverse this trend, the AMP should implement tighter control mechanisms that ensure that infrastructure and housing needs are fully met through the reuse of urban areas that are already sealed. However, given that the share of impermeable soil in most urban areas is already significantly high, there will have to be a careful choice of locations where intensifying land use will cause less environmental damage. It is concluded that the degree of soil sealing within urban areas is fundamental for deciding on the interventions to be carried out to reduce net land take and for defining a policy towards meeting the 2050 target. [ABSTRACT FROM AUTHOR]

Traditional drainage methods for marine reclamation typically consume large amounts of energy and have a negative environmental impact. The siphon-vacuum drainage method (SVD) automatically forms a vacuum and drains using less energy. It has significant potential for research and application. In this study, a theoretical model is used to calculate the vacuum formation process and drainage rate. Qualitative analysis and global sensitivity analysis were conducted to investigate the effect of various factors in the SVD on vacuum formation and drainage. The qualitative analysis suggests that modifying the length and diameter of the siphon pipe and the thickness of the sealing soil column to increase the siphon rate can improve the vacuum degree and drainage efficiency. Sobol global sensitivity analysis reveals that the sealing soil column thickness is the main factor affecting the vacuum, with a first-order sensitivity index accounting for up to 79.48%. The impact of cylinder diameter and the local resistance coefficient (0.43%) can be almost neglected. A fitting equation for estimating the maximum achievable vacuum is provided. Calculations show that the vacuum formed by the SVD can reach over 80 kPa. This work can help optimize SVD design and advance environmentally friendly marine reclamation projects. [ABSTRACT FROM AUTHOR]

Soil sealing treatment is an effective chemical weed control method in rapeseed field. To evaluate the effects of different soil-applied herbicides on soil microorganisms in rapeseed field, 16S rRNA amplicon sequencing was used to analyze the changes in soil microbial structure and diversity after treatment with four commonly used soil-applied herbicides alachlor, acetochlor, metochlor and s-metolachlor. The results showed that soil-applied herbicide treatments could significantly reduce soil bacterial diversity in rapeseed fields, and alachlor had the greatest effect on soil bacterial diversity. However, after a period of herbicide treatment, the diversity and richness of the soil bacterial community gradually recovered. Soil-applied herbicide treatment had great influence on Actinomycetes, Acidobacteria and others in rapeseed soil, and alachlor treatment showed the greatest change in soil bacteria at phylum level compared with other herbicides. After 60 days of treatment with soil-applied herbicides, the abundances of functional bacteria related to pollutant degradation, denitrification, photosynthesis, pathogen growth inhibition and rhizosphere growth promotion were increased, whereas functional bacteria associated with the absorption of nutrients and excretion of metabolites were reduced. Overall, the results indicated that the soil-applied herbicides had a certain effect on soil microbial diversity and community structure in rapeseed field, but the effect of herbicides on soil microbial diversity gradually decreased along with the time of treatment. [ABSTRACT FROM AUTHOR]

Methane spikes observed in the Martian atmosphere require the abrupt release of large amounts of methane from the Martian subsurface. The mechanism for such release has not been identified. We tested whether gas traps can form under Mars‐like conditions in the shallow Martian regolith due to salt migration in the icy soil. Experiments were performed on various soil samples in a Mars Simulation Chamber comprising different perchlorate salts and water concentrations mixed with JSC Mars‐1A. Inside the chamber, the samples were exposed to a range of temperatures from −20°C to 10°C and maintained CO2 gaseous pressure between 8 and 10 mbars. As a methane analog, Neon was injected periodically underneath the soil sample. It was found that over a wide range of Mars‐like soil parameters, a gas impermeable soil seal can form over a relatively short period (3–13 days) but requires 5%–10% of perchlorate salt content in the soil. It was determined that such a seal could sustain several mbars of neon above the Martian atmospheric pressure in the soil. Based on our experiments, substantial amounts of gaseous methane may accumulate under the soil seal and get released abruptly into the atmosphere upon seal cracking. An abrupt release of methane from the shallow subsurface may help explain methane variability at the Martian surface, as the Mars Science Laboratory detected. Plain Language Summary: Spikes of atmospheric methane on Mars, recently observed by the Mars Science Laboratory mission, are puzzling. To explain rapid variations in methane abundance in the Martian atmosphere, methane has to be released abruptly. Our experiments in the Mars simulation chamber demonstrated that perchlorate salts can be transported toward the surface regolith via water migration and subsequent sublimation. We showed that under Mars‐like conditions, the soil with migrated salts can become cemented and form a solid gas impermeable seal. Methane and other volatiles can accumulate under the soil seal. Methane seasonal variability and occasional methane spikes in the Gale crater on Mars can be due to a sudden release of methane from the soil gas pockets when the Curiosity rover breaks soil seals by moving or drilling. Key Points: Gas impermeable seals can form in Mars‐like conditions in the soil with 5%–10% perchlorate salts by mass and a shallow permafrost layerMethane could accumulate under the seal in the shallow subsurface and be released abruptly into the atmosphere when the seal breaks [ABSTRACT FROM AUTHOR]

Soil crusting (surface sealing) is widespread and serious in ecotouristic game parks and reserves in southern Africa, and especially South Africa. In this study, mineral soil crusts were found to be the problem in the Dinokeng Game Reserve (DGR), South Africa. Large areas of bare soil crusted areas were found in this reserve. The cause of this crusting was found to be historical agricultural practices such as cultivation with maize on non-arable soils and overgrazing by cattle. Negative impacts of soil crusting include reduction of water infiltration, leading to increased runoff and erosion and induced drought; inhibiting soil aeration; inhibiting germination and seedling emergence; and inhibiting root functioning and development. In this study in the DGR, a bare crusted area, where cultivation was abandoned 50 years before and there has been no recovery to rangeland since then, was selected for a field trial to determine the effectiveness of the application of various soil ameliorants on soil crust alleviation and improvement of water infiltration rate. The following ameliorants were evaluated: polyacrylamide (PAM) at levels of 5 and 20 kg/ha, gypsum at 2.5 t/ha, and molasses meal at 5 t/ha, as well as combinations of PAM and molasses meal, PAM and gypsum and gypsum and molasses meal. Brush packing, without any ameliorant applied, was also included as treatment, as well as a control with no treatments. PAM treatments increased final infiltration rate (FIR) by between 100–206%. The high efficacy of the lowest PAM treatment is at a cost of only USD 15 per hectare economically important. On the studied soil gypsum application reduced FIR by 81%, while molasses meal had minimal effect. These ameliorants can therefore not be recommended on such soil. [ABSTRACT FROM AUTHOR]

This study deals with how shifting (jhum) cultivation affects the physical, chemical, and hydraulic properties of soil-water resources in the vadose zone. This included analysis of changes in parameters such as organic matter concentration, pH, nutrient levels, and hydraulic conductivity, as well as soil texture and structure. For this, a microcatchment situated in the Aizawl District of Mizoram State in Northeast India was selected. Three sites were chosen in the catchment, each representing a different stage of cultivation viz. (1) Nonjhum land (NJL) or fallow land, (2) Newly burnt jhum land (NBJL), and (3) Cultivated jhum land (CJL). By selecting shifting (jhum) sites with similar topographical conditions, this study provides a better understanding of the effects of shifting (jhum) cultivation on the physicochemical properties of the local soil and water resources. To assess the effects of shifting (jhum) cultivation at three different stages of shifting (jhum), soil samples were collected from multiple depths, including the top surface, 5 cm, and 55 cm of the vadose zone. Water and sediment samples were also collected from three streams flowing downstream from these three shifting (jhum) sites. Findings reveal that both mean hydraulic conductivity and surface infiltration values were highest at NBJL. Furthermore, soil indices including the soil aggregate stability index (SASI), soil sealing index (SSI), and Forestier index (FI) were estimated to understand the properties of surface soils and their micronutrient and macronutrient availability. According to the SASI analysis, all soil samples from the shifting (jhum) sites exhibited a stable soil structure. The SSI results indicated that the surface soils had no risk of thrust or erosion due to shifting (jhum) practice. The FI assessment revealed that the vadose zone soils possessed abundant nutrient reserves. Soil texture in all three areas was found almost similar, with maximum percentages of medium to fine sand and the texture varying from sandy loam to loamy sand. Total organic component (TOC) (%) of surface samples were highest at CJL at 8.73% compared to 7.62% at NBJL and 7.47% at NJL. To study the seasonal variability of sediment quality, premonsoon, and monsoon comparison of all the stream sediment analysis was conducted. Macro and Micronutrients (phosphorus, potassium, calcium, magnesium, manganese, iron, sodium, and zinc) were quantified for soil and sediment samples to study the changes in their concentration at various stages of the shifting (jhum). [ABSTRACT FROM AUTHOR]

The physico-mechanical quality of the seed bed is extremely important not only for the soil air-water dynamics, but also for the germination, seedling emergence, and development of the plants. The crust layer formed after precipitation and irrigation in soils with poor structural properties is among the most important indicators of the lower seedbed quality. While there are different applications to increase the physico-mechanical quality of the seedbed, there are also cement applications that provide rapid aggregate formation and stability. The effects of cement application on the soil mechanical quality and seedling emergence of clay textured soil with poor structural characteristics were investigated in the present study. For this purpose, a total of 36 small plots with a size of 2.4 m2 were created. Cement was applied at 0.25–0.5–1 and 2% doses to 18 plots in the fall period, and to the other 18 plots in the spring period. After the treatment, soil samples were taken for analysis before the planting period and the number of seedling emergence was determined by planting the bean plant during the planting period. According to the results of the study, it was found that cement applied in two periods caused an increase in soil aggregate stability, decreased penetration resistance, modulus of rupture, and dispersion rate, and increased water holding capacity to a limited extent. On the other hand, cement application also had positive impacts on the emergence of the bean plant. The 1% dose of the spring application of cement was more effective on the determined soil structural characteristics and seedling emergence. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibet Plateau is now experiencing ecological degradation risks as a result of climate change and human activities. The alpine grassland ecology in permafrost zones is fragile and susceptible to deterioration due to its high altitude, low temperature, and limited oxygen, which complicates the repair of damaged land. Biological soil crusts (BSCs) are crucial for land restoration in plateau regions because they can thrive in harsh conditions and have environmentally beneficial traits. Inoculated biological soil crust (IBSC) has shown success in low-altitude desert regions, but may not be easily duplicated to the plateau environment. Therefore, it is essential to do a comprehensive and multifaceted analysis of the basic theoretical comprehension and practical application of BSCs on the Tibetan Plateau. This review article aims to provide a brief summary of the ecological significance and the mechanisms related to the creation, growth, and progression of BSCs. It discusses the techniques used for cultivating BSCs in laboratories and using them in the field, focusing on the Qinghai-Tibet Plateau circumstance. We thoroughly discussed the potential and the required paths for further studies. This study may be used as a basis for selecting suitable microbial strains and accompanying supplemental actions for implementing IBSCs in the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

Flash flooding is among the most hazardous natural events in the US and globally. Hydrologic simulations are key tools for flash flood forecasting, particularly in poorly gauged or ungauged catchments, and infiltration models are a crucial component of any hydrologic simulation. Ideally, model parameters are calibrated based on observations. In practice, calibration and validation are often not possible due to a lack of observations. This paper contributes new guidance for parameter estimation of three infiltration models using plot-scale rainfall simulation. All three models, namely, initial-constant (IC), linear-constant (LC), and the Green-Ampt (GA) models, will be available in the next release of the widely used Hydrologic Engineering Center–Hydrologic Modeling System software. Results show that model parameters are sensitive to soil texture, antecedent moisture conditions, and the presence of a physical soil crust. [ABSTRACT FROM AUTHOR]

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

In order to address the problems of soil crusting and the lack of soil fertility produced by long-term planting of tobacco, an operation device integrated the functions of deep loosening, fertilizer application, and riding was proposed in this study. The agronomic requirements of tobacco planting and the ecological benefits of organic fertilizers and other advantages were considered during the design of the device. The device was consisted of the frame, deep loosening fertilizer shovel, and ridging part. ANSYS software was used to establish the finite element model of the frame and deep loosening fertilizer shovel, and the modal simulation experiment was conducted. Results show that, under the torsion and braking interaction, the stress change of the Frame is not obvious, and the stress of the shovel tip is mainly concentrated on the combination of shovel handle and shovel body, with the stress change of other areas being insignificant. The modal analysis of the Frame shows that its resonance frequency is 61.138 Hz, and the error rate between the modal simulation and the modal test is less than 10%, which verified the feasibility of the structural design. The results of this study provide technical references for the structural design of a device for improving deep soil characteristics. [ABSTRACT FROM AUTHOR]

In recent decades, agricultural sustainability has been negatively affected by the structural degradation of soils resulting from excessive land use. In this research, the impact of different irrigation methods applied for five years in a region experiencing crusting issues on the soil's physical quality was investigated. Soil samples were taken from a region where wheat is grown and four different irrigation systems [Natural rainfall (NR), linear pivot irrigation (LPI), subsurface drip irrigation (SDI), and sprinkler irrigation (SI)] are employed, at depths of 0-20 cm, from both degraded and undegraded soils. The soil's mean weight diameter (MWD), water-resistant aggregates (WRA), saturation level (Ts), field capacity (FC), wilting point, available water content (AWC), aeration capacity, modulus of rupture, plastic limit (PL), liquid limit (LL), and plasticity index (PI) were determined. The soil's WRA were found to be the lowest at 7.76% in the NR, but this result increased by 150.64% to 19.45% in the SDI. The MWD values of the soils in the NR system were found to be 0.178 mm and it has been found to increase in the SDI system, reaching 0.467 mm. In the SDI system, the highest values were obtained for Ts, FC, and AWC. While the modulus of rupture was found to be 151.56 kPA in the NR, it was found 154.4, 44.78 and 154.2 kPA in the LPI, SDI and SI areas, respectively. The PL, LL, and PI values of the soils were not affected by different irrigation systems, and values were determined as 44.57%, 21.14%, and 23.44%, on average respectively. In this direction, the necessity of monitoring the results of soil aggregate stability and water characteristics for many years and examining them in different soil types has emerged. In addition, it has been suggested that the possible effects of irrigation systems should be considered for the sustainable use of lands. [ABSTRACT FROM AUTHOR]

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Soil sealing is a threat to soil and its ecosystem services. One of the main drivers of soil sealing is land degradation resulting from the expansion of urban areas, where it leads to such problems as the growing risk of flooding and local inundations, urban heat islands, or water shortages. The article focuses on analyses and quantification of the general degree of soil sealing in 2012-2018 in eight functional urban areas (FUA) in Poland, taking into account their division into the urban core (UC) and the commuting zone (CZ). We used the high resolution layer imperviousness density (HRL IMD) data to quantify soil sealing as well as data on land cover and land use with different spatial resolutions, i.e. from the European Urban Atlas project (UA) and the National Database of Topographic Objects (BDOT10k) to quantify artificial surfaces. The research determined the spatial differentiation of UCs and CZs in terms of the degree of soil sealing. We further observed higher average growth of sealed land in CZs. Quantitative and spatial analyses determined the spatial patterns of soil sealing in the FUA in Poland. Soil sealing intensified from 2012 to 2018. The process should be expected to continue in the coming years in light of the continuous transformation of vegetated areas into artificial ones. The conclusions should be considered valuable for the implementation of the spatial policy concerning sustainable land use and soil protection in suburban areas. [ABSTRACT FROM AUTHOR]

Soil erosion significantly affects various soil properties and processes, yet its impacts on soil microbial populations remains unclear. Understanding the effects of soil erosion on soil microbial properties enables the formulation of recommendations to protect soils and reduce their vulnerability. This study aimed to determine the effects of rainfall intensity and slope on soil crusting, erosion and bacterial communities in soils with various texture and mineralogy. Three kaolinitic soils with low to medium clay content (K1, K2, and K3) and three smectitic soils with high clay content (S1, S2, and S3) were subjected to simulated rainfall at three intensities (45, 70 and 100 mm/h) and two slopes (5° and 8°). Infiltration rate was measured using a graduated cylinder in 2-minute rotations of the simulator. Runoff and sediment yield were collected in a beaker. Crust strength was measured using a cone penetrometer, and its thickness was determined with a vernier caliper. Bacterial isolates were obtained by plating serial dilutions in nutrient agar and incubating them at 25°C for 24–48 h48 hous. The phosphate solubilising bacteria were then identified. The smectitic soils formed the strongest crusts with S2 exhibiting significantly (p

Biological crusts are a collection of mosses, lichens, algae, fungi and heterotrophic bacteria that live in different forms within a few millimeters above the soil surface. These crusts play an important role in the development, stability and improvement of the nutritional status of the surface soil. Therefore, this study was conducted to investigate the role of biocrust sequences on the soil characteristics in the Inche Barun region, Golestan province (Iran). In the study area, biological and physical crusts as well as the soil under their surface were sampled after identifying the sequences of biocrust (moss, lichen and cyanobacteria). Then, the physicochemical characteristics of soil under their surface (In the depths 0–2, 2–4, 4–8, 8–10, 10–25, and 25–50 cm) were measured. The results showed that the presence of biological crusts compared to physical crust in the surface parts (0 to 2 cm depth) improved the physicochemical properties of the soil. The content of nitrogen, soil organic carbon, phosphorus, cation exchange capacity, sodium, potassium and mean-weight diameter of soil in the soil under their surface increased from the first (physical crust) to the last sequence (moss biological crust). The values of these parameters decreased with increasing soil depth. Biological crusts improve soil stability and reduce soil erosion. They also serve as food sources for organisms residing in soils. Therefore, it can be concluded that the presence of biological crusts on the soil surface improves soil quality. [ABSTRACT FROM AUTHOR]

Testing and improving the capacity of soil erosion and sediment delivery models to simulate the intra-annual dynamics climatic drivers and disturbances (e.g. vegetation clearcutting, tillage events, wildfires) is critical to understand the drivers of the system variability. In seasonally changing agricultural catchments, explicit temporal dynamics are typically neglected within many soil erosion modelling approaches, in favour of a focus on the long-term annual average as the predictive target. Here, we approach the trade-off between the need for model simplicity and temporally-dynamic predictions by testing the ability of a low-complexity, spatially distributed model (WaTEM/SEDEM), to decompose the 15-day dynamics of soil erosion and sediment yield. A standardised parameterisation and implementation routine was applied to four well-studied catchments in North-West Europe with open-access validation data. Through the testing of several alternative model spatial and connectivity structures, including the addition of an empirical runoff coefficient, we show that a temporally-static calibration of transport capacity cannot adequately replicate the relative seasonal decoupling of gross (on-site) soil erosion and sediment delivery. Instead, embedding seasonality into the calibration routine significantly improved the model performance, revealing a negative relationship between gross (pixel-scale soil displacement) and net erosion (stream channel sediment load) throughout the year. By incorporating temporal dynamics, the relative net effect is a reduction in the magnitudes of the spatially-distributed sediment fluxes at aggregated timescales, compared to a temporally-lumped approach. Published catchment observations infer that the efficacy of sediment delivery via overland flow is strongly reduced in the summer by abundant vegetative boundaries and increased in the winter via soil crusting and its promotion of runoff. Models operating at temporally-aggregated timescales should account for the possibility of decoupling in time and space between gross erosion and sediment delivery in arable catchment systems, related to alternations between transport- and detachment-limited sediment transport capacity states. Despite the complexities involved in the temporal downscaling of WaTEM/SEDEM, we show the utility of this approach to: 1) identify key missing information components requiring attention to reduce error in gross erosion predictions (e.g. more consideration of antecedent soil conditions), 2) form a basis for strategically adding physical process-representation, with a focus on maintaining low model complexity while improving predictive skill, and 3) better understand the spatial and temporal interdependencies within soil erosion models when undertaking upscaling exercises. [ABSTRACT FROM AUTHOR]

Desert algae are important components of the desert soil crust and play an essential role in desert soil ecosystem development. Owing to their special habitat, desert algae are often exposed to harsh environments, among which drought represents the most common stress. Green algae are considered to have drought tolerance potential; however, only a few studies have investigated this. In this study, we selected the green alga Chlorella sp., which was isolated from desert soil, and studied its physiological response to polyethylene glycol (PEG) 6000‐induced drought stress. The results showed that drought stress can affect the photosynthetic efficiency of Chlorella sp., reduce its water retention ability, and destroy its ultrastructure. However, Chlorella sp. can cope with drought stress through a series of physiological regulatory strategies. Protective strategies include quick recovery of photosynthetic efficiency and increased chlorophyll content. In addition, induced synthesis of soluble proteins, lipids, and extracellular polysaccharide (EPS), and accumulation of osmotic regulatory substances, such as sucrose and trehalose, also contribute to improving drought tolerance in Chlorella sp. This study provides insights into the physiological responses of Chlorella sp. to drought stress, which may be valuable for understanding the underlying drought adaptation mechanisms of desert green algae. [ABSTRACT FROM AUTHOR]

Wind erosion plays an essential role in the production of sediment for dust storms and occurs when strong and continuous wind interacts with dry, fine-grained and loose soil. Identifying dust production centers is the first step in prioritizing different areas for executive operations to reduce dust and determine its control methods. Jazmurian area is one of the areas where the intensity and frequency of dust events have increased in recent years and caused a lot of damage. The purpose of this research is to determine the areas prone to dust production and sensitive to wind erosion using the ILSWE model in the Jazmurian wetland basin. This model is based on five effective factors of climate erosivity, soil erodibility, soil crust, vegetation cover, and surface roughness. Maps of temperature, precipitation, wind speed, percentage of sand, silt, clay, calcium carbonate, EVI and land use were used to calculate these factors. After calculating each factor, ILSWE index was calculated by multiplying them. Finally, sensitive areas were identified by classifying this index in Arc GIS software. The ILSWE classification map showed that 46.72% of the studied area is in very low sensitivity class, 16.56% in low class, 13.67% in medium class, 12.41% in severe class and 10.64% in class Very severe sensitive to wind erosion. Severe and very severe sensitivity class was considered as the center of dust generation. The results showed that the southern (wetland area and its surroundings), west, southwest, east and southeast areas of the Jazmurian wetland basin are prone to dust production and wind erosion. These areas are mostly located in areas without vegetation (barren areas), salt marshes and sand dunes; which shows the importance of vegetation in reducing producing dust. On the other hand, the topography, the presence of wind and the characteristics of the soil in these areas help to produce dust. In general, the results of this research showed that the ILSWE model has a suitable efficiency for determining areas prone to wind erosion and dust production. [ABSTRACT FROM AUTHOR]

Decades of intense tillage have created the problem of surface sealing in loam soils across the Mid‐South United States and beyond. These soils exhibit low organic matter, poor aggregate stability, and ultimately low infiltration rates that decrease rainfed crop productivity and increase irrigation water demand. This research quantified the effects of soil management practices on rainfed maize (Zea mays L.) yield, furrow water infiltration, and soil moisture in Commerce very fine sandy loam and silt loam near Stoneville, MS. The six treatments included conventional tillage (CT), cereal rye (CR; Secale cereale L.), furrow diking (FD), no‐till (NT), polyacrylamide (PAM), and subsoiling (SS). No other treatment achieved a significantly higher maize grain yield than the CT control treatment in both years consistently. Single‐ring infiltrometer results indicated no significant differences among CT, CR, PAM, and SS in 2022 and between CT and NT in 2021. Neutron attenuation found that total soil water within the top 1 m was not significantly different among CT, FD, and SS on any of the eight measurement dates throughout the 2022 maize reproductive period. However, soil moisture was numerically lower for FD in the late reproductive stages. These findings suggest that environmental factors and other agronomic operations may counteract conservation practices, limiting their effectiveness at reducing irrigation requirements to mitigate groundwater depletion in the Mississippi River Valley Alluvial Aquifer. Core Ideas: None of the five conservation practices consistently surpassed conventional tillage in rainfed maize yield.The cereal rye, no‐till, polyacrylamide, and subsoiling treatments did not accelerate furrow water infiltration.The furrow diking and subsoiling treatments did not increase total soil water within the top 1 m.Better timing and methods of conservation intervention are needed to enhance Mid‐Southern US water sustainability. [ABSTRACT FROM AUTHOR]