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The soil mantle of the tropical karstic landscapes of Southern Mexico was shaped by specific processes of pedogenesis and long-term human impacts of ancient Maya agriculture. To understand the interaction between natural and human-induced soilforming processes in the calcareous mountains of Chiapas state, we studied soil toposequences around the Classic Maya site of Budsilhá and related them to the archaeological evidence of settlement and land-use distribution. Soil chemical analysis, micromorphological observations, and clay mineral identification were carried out in key soil profiles at the main geoforms. Limestone hills are occupied by shallow Rendolls which are usually perceived as incipient soils. However, high content of silicate clay composed of kaolinite and vermiculite and ferruginous clayey soil material observed at macro- and microscale backed the hypothesis that these soils were formed from the residues of thick Terra Rossa after their erosion. Swampy lowlands are occupied by thick clayey gleyic soils with clay mineral assemblages similar to those in the upland Rendolls. We suppose that the mineral matrix of the lowland soils is largely derived from the pedosediments of eroded upland Terra Rossa, which lost original ferruginous pigmentation and aggregation due to redoximorphic processes. Some wetland soils contain neoformed gypsum that is atypical for humid tropics; sulfidesulfate transformation under fluctuating redox conditions could promote gypsum synthesis. Ancient Maya land use was closely related to soil-geomorphic conditions: settlements with homegardens occupied calcareous hills, whereas the primary agricultural domain was developed on lowland soils after their drainage by artificial canals. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bidirectional static loading tests were conducted on two strain-gage instrumented barrettes installed to 72 m depth in Ho Chi Minh City, Vietnam. The barrettes were to support a 16-storey building with 5 basements. The soil profile comprised layers of medium coarse to fine sand, medium clay, firm to stiff clayey soil, and dense sandy silt. The region is experiencing an ongoing land subsidence affecting the upper about 40 m of soil and, on average in the city, the ground surface is currently settling 16 mm/year. The test records were processed by means of effective stress analysis to provide the axial pile force distribution, load transfer functions, and equivalent head-down load–movement curve. The analysis was then used to obtain the equivalent pile-head load–movement response adjusted to the planned 22 m deep basement excavation. Load transfer functions were back-calculated from the test records and indicate that the construction will show somewhat large load-transfer movement. However, because the equilibrium plane will be below the subsiding layers, below 40 m depth, downdrag is not expected to affect the building. The load response of the barrettes is compared to the results of a bidirectional (BD) loading test on a 1.8 m diameter bored pile at an adjacent project. [ABSTRACT FROM AUTHOR]

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

In heavy soils, changes in humidity incur soil volume changes. In the horizontal plane, these are manifested by cracks formation and in the vertical plane by the movement of the soil surface. Cracks have a significant impact on hydrodynamics of the soil profile. The work is based on the hypothesis that soil volume changes depend on both the content of clay particles in soil and soil volumetric moisture. The aim of the work is to measure and analyze the changes in the width of the cracks and their reaction to the changes in volumetric soil moisture. One of the objectives of the work was to design a simple tool for accurate measurement and calculation of the crack width on the soil surface. For the study of crack width, a soil profile in an area on the East Slovakia Lowland was selected. The profile was examined under conditions of extreme drought, at the turn of July and August 2022. Crack width varied between 1.0 cm and 3.3 cm. The calculation procedure was evaluated as satisfactory for estimating the change in crack width on the soil surface. [ABSTRACT FROM AUTHOR]

The pre-emergent herbicide indaziflam is efficient in the management of weeds in eucalyptus crops, but this plant may develop less in soil contaminated with it. The objective was to evaluate the levels of chlorophylls a and b, the apparent electron transport rate (ETR), growth and dry mass of leaves, stems and roots of Clone I144, in clayey soil, contaminated with the herbicide indaziflam and the leaching potential of this herbicide. The design was completely randomized in a 3 × 5 factorial scheme, with four replications. The leaching of indaziflam in the clayey soil profile (69% clay) was evaluated in a bioassay with Sorghum bicolor, a plant with high sensitivity to this herbicide. The injury and height of this plant were evaluated at 28 days after sowing (DAS). We believe that this is the first work on Eucalyptus in soil with residues of the herbicide indaziflam. Chlorophyll a and b contents and ETR, and height and stem dry mass of Clone I144, were lower in soil contaminated with indaziflam residues. The doses of indaziflam necessary to cause 50% (C50) of injury and the lowest height of sorghum plants were 4.65 and 1.71 g ha−1 and 0.40 and 0.27 g ha−1 in clayey soil and sand, respectively. The sorption ratio (SR) of this herbicide was 10.65 in clayey soil. The herbicide indaziflam leached up to 30 cm depth at doses of 37.5 and 75 g ha−1 and its residue in the soil reduced the levels of chlorophylls a and b, the apparent ETR and the growth of Clone I144. [ABSTRACT FROM AUTHOR]

The enrichment factor (EF) is one of the most commonly used indices for determining the source of air, water and soil pollution. However, concerns have been raised about the accuracy of the EF results because the formula leaves the choice of background value to the researcher's discretion. The EF was used in this study to assess the validity of such concerns and to determine heavy metal enrichment in five soil profiles with different parent materials (alluvial, colluvial, and quartzite). Moreover, the upper continental crust (UCC) and specific local background values (sub-horizons) were used as the geochemical backgrounds. When UCC values were applied, the soils were moderately enriched in Cr (2.59), Zn (3.54), Pb (4.50) and Ni (4.69), and significantly enriched in Cu (5.09), Cd (6.54) and As (6.64). Using the sub-horizons of the soil profiles as a background value, it was found that the soils had "moderate enrichment" by As (2.59) and "minimally enrichment" by Cu (0.86), Ni (1.01), Cd (1.11), Zn (1.23), Cr (1.30), and Pb (1.50). As a result, the UCC reported an inaccurate conclusion indicating that soils were 3.84 times more heavily polluted than they were. In addition, the statistical analyses performed in this study (Pearson correlation analysis and principal component analysis) revealed that the percentage of clay in the soil horizons and the cation exchange capacity had strong positive relationships (r ≥ 0.670, p < 0.05) with certain heavy metals (Al, Zn, Cr, Ni, Pb and Cd). These findings indicated that sampling from the "lowest horizons" or "parent materials" of the soil series would yield the most accurate results in determining the geochemical background values in agricultural areas. [ABSTRACT FROM AUTHOR]

Parent material and topography are among the soil-forming factors that affect soil evolution by influencing different parameters. This study was conducted to compare the effect of marl and calcareous parent materials in different slope positions, including the summit, shoulder, foot-, and toe-slopes on soil clay mineralogy in the Karoon 3 Basin, east of Khuzestan Province. Four soil profiles in each of the two topo-sequences were dug. They were sampled based on their genetic horizons and some physical, chemical properties, and clay mineralogy were measured. The results showed that the type and abundance of clay minerals identified for both parent materials were more affected by topo-sequence position. The composition of minerals identified in the topo-sequence with marl parent materials included kaolinite, palygorskite, smectite, chlorite, mica, and quartz, and in the topo-sequence with calcareous parent materials, palygorskite, smectite, chlorite, mica minerals, and quartz, and most of the identified minerals were also observed in all positions in the C horizon. However, in marl parent materials kaolinite, and calcareous parent materials, smectite seems to have been formed pedogenically. The result of the association between Weaver and Beck indicated that most of the clay minerals are in the equilibrium of Palygorskite. [ABSTRACT FROM AUTHOR]

Purpose: Environmental controls of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) in the subsoil are important for understanding nutrient cycles; however, these are poorly understood in subtropical paddy soils, especially lacking systematic regional soil profile investigations in the subsoil. The study aims to evaluate the role of environmental factors on concentrations and ratios of SOC, TN, and TP in subsoil (20–100 cm) vs. topsoil (0–20 cm). Methods: We sampled 166 soil cores (1-m depth) from paddy fields across 10 typical counties in 4 provinces of subtropical China. Soil properties of SOC, TN, TP, pH, bulk density, and clay were determined in each soil layer. Spearman correlation analysis and random forest model were performed to correlate environmental factors with soil nutrients and to rank their relative importance throughout the soil profile. Results: SOC was strongly coupled with TN and both decreased with soil depth. However, TP was high in topsoil and did not change in the subsoil. Thus, the soil C to N ratio (12.88–14.93) exhibited minimal variation, whereas N to P (30.93–68.99) and C to P (2.52–5.59) ratios decreased markedly with the soil depth. As compared with topsoil, subsoil revealed similar dominant negative effects of climate (temperature, precipitation) and bulk density on the concentrations and ratios of SOC, TN, and TP. The soil clay had no effect on SOC and TN, but was the dominant control on TP throughout the soil profile. The influences of straw incorporation and chemical fertilization on SOC and TN were primarily observed in topsoil. Conclusions: There were dominant climate controls (temperature and precipitation) of soil C–N–P concentrations and ratios in the subsoil, although different soil factors control SOC and TN vs. TP. These findings highlight the importance of managing subsoil nutrients in subtropical paddy soils, since they are consistently sensitive to climate as topsoil nutrients. [ABSTRACT FROM AUTHOR]

Flooding occurs when water is in excess and can no longer be evacuated normally. The nature of the soil has been identified as one of the major causes of flooding; hence, this study aimed is to show the influence of the physico-chemical properties of the soil on the recurrence of flooding in the Mbo plain. Four soil profiles were carried out on the alluviums according to the altitudes. These profiles were described, and undisturbed soil samples were taken. Then, measurements of the infiltration rate of water in the soil by the Porchet method were taken in sixteen sites. Finally, soil samples taken by auger and core sampling were studied in the laboratory. Physico-chemical parameters such as grain size, porosity, moisture, pH, compactness and organic matter were determined. Infiltration tests carried out in situ using the Porchet method revealed a hydraulic conductivity between 10–5 and 10–7 m/s, characteristic of a semi-permeable soil. This low value of permeability results from the morpho-structural arrangement and the chemical composition of the soils of the plain. These soils are hydromorphic, which means that they are constantly flooded and temporarily waterlogged. They are more or less sandy-clay on the surface, and very clayey at depth, generally from 25 cm. The very clayey soils at the base considerably slow down infiltration and act as a real barrier layer that prevents water from infiltrating, resulting to intense runoff. These soils are very porous and compact with a fairly high water content of up to 71%. This work allows us to conclude on the role of intrinsic soil properties on the genesis of floods in lowland areas. As in many plains in Africa and in the world, the nature of the soil in the Mbo plain is a natural predisposing factor to flood risks. The methods used can be applied in areas with the same characteristics as the Mbo plain. [ABSTRACT FROM AUTHOR]

In this paper, the finite element method (FEM) is applied to calculate the bearing capacity of two footings having the aspect ratio L/B (where L and B are the length and width of the footing, respectively) equal to 1, 2 resting on one-layer and two-layer soil. Soil profile contains two soil types including sand and clay. The soil strip is 500mm × 500mm × 350mm; however, only a quarter of the model (250mm × 250mm × 350mm) is examined in the study. Two primary situations are investigated in this study. In the first situation, the one-layer system is supposed to be sandy soil with footing overlays on medium-dense sand. The soft clay/stabilized clayey layer is supposed to be on top of the sandy soil in the second condition, with the footing resting on top of the soft clay/stabilized clay. The influence of layer thickness, aspect ratio, and material property on the bearing capacity value and footing failure mechanism is studied for eight different combinations of layered soil. The bearing capacity for a one-layer case is also estimated, and it agrees well with Vesic (1973), Hansen (1970), and Terzaghi's (1943) equations. The bearing capacity of footings is observed to decline when the height of unstabilized clayey soil increases, and it increases when clayey soil is stabilized with molasses, waste foundry sand, and lime alone and in combination with each other. [ABSTRACT FROM AUTHOR]

The main objective of this research was to develop a model for predicting weather-induced volumetric changes. Based on the unique soil properties of cracked expansive clays, the model included flow-through estimations and heave-settlement predictions. The water content and volume change were trained using long-term monitoring data (1960–1968) in Regina (Canada). The water flux was found to increase from − 0.3 mm/day to − 0.05 mm/day (1960–1963), followed by a further increase to 0.1 mm/day (1964–1965), and then by a bounce back to − 0.2 mm/day (1966–1968). The monthly flux-in and flux-out closely matched one another because evaporation equalled infiltration whereas snowmelt resulted in runoff. The water content varied during summer following a cyclic trend with an initial decrease in April–June and a subsequent rebound in July–October. This delay is due to the slow advance of the wetting front through the soil profile that subdued large variations in surface saturation below 0.5 m depth. The fluctuations were high (28% to 15%) in 1960–1963 and gradually decreased (35% to 33%) in 1964–1965 and remained similar in the subsequent dry years (1966–1968). Volume changes were found to be ± 20 mm in water deficient years (1960–1963) and decreased to half (± 10 mm) in water surplus years (1964–1965) and subsequent water deficient years (1966–1968). The large surface variations gradually decreased with depth and were found to be negligible at 3.1 m below the surface due to the lower cumulative values at depth. The model was successfully validated for compacted soils with respect to depth (1.2 m and 2.0 m) as well as asphalt cover and grass cover using 2006–2007 and 2009–2010 field data. [ABSTRACT FROM AUTHOR]

Restoration of anthropogenically disturbed soils is an urgent problem in modern ecology and soil biology. Restoration processes in northern environments are especially important, due to the small amounts of fertile land and low levels of natural succession. We analyzed the soil microbiota, which is one of the indicators of the succession process is the soil. Samples were obtained from three disturbed soils (self-overgrown and reclaimed quarries), and two undisturbed soils (primary and secondary forests). Primary Forest soil had a well-developed soil profile, and a low pH and TOC (total organic carbon) amount. The microbial community of this soil had low richness, formed a clear remote cluster in the beta-diversity analysis, and showed an overrepresentation of Geobacter (Desulfobacteriota). Soil formation in clay and limestone abandoned quarries was at the initial stage, and was caused by both a low rate of mineral profile formation and severe climatic conditions in the region. Microbial communities of these soils did not have specific abundant taxa, and included a high amount of sparse taxa. Differences in taxa composition were correlated with abiotic factors (ammonium concentration), which, in turn, can be explained by the parent rock properties. Limestone quarry reclaimed by topsoil coverage resulted in an adaptation of the top soil microbiota to a novel parent rock. According to the CCA analysis, the microbial composition of samples was connected with pH, TOC and ammonium nitrogen concentration. Changes in pH and TOC were connected with ASVs from Chloroflexota, Gemmatimonadota and Patescibacteria. ASVs from Gemmatimonadota also were correlated with a high ammonium concentration. [ABSTRACT FROM AUTHOR]

This paper presents a real case study of a micropiling process that was developed to stop the continuous tilting of a 9-story residential building in Dakahlia, Egypt. Shortly after the construction of the building, the surface raft foundation exhibited severe settlement problems. In order to carry out a geotechnical investigation, boreholes were drilled around the constructed building. It was discovered that in addition to a thick, soft clay layer in the soil profile, there was also a crucial eccentricity between the centroid of the total building loads and the centroid of the raft. The issue needed to be addressed immediately, and a micropiling system was proposed to satisfy the geotechnical and structural conditions associated with the case history. In addition to describing the field measurements, detailed methodology, and micropile installation process, this paper also presents three different design approaches for determining the number and location of the micropiles. Although the underpinning process itself initially induced some settlement, micropiling the raft proved to be an efficient solution to stop the continuous tilting of the building. A micropile load test confirmed the advantageous effect of the grouting technique used for Type B micropiles, where the grout is injected under high pressure. [ABSTRACT FROM AUTHOR]

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

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

Soil is one the most extracted natural raw materials. The vast expanses of fertile alluvial soils of the Indo Gangetic Plains have long remained as abundant soil resource pool for brick manufacturing and construction sectors. Unmonitored continuous removal of soil is reported to cause depletion of soil reserves, loss of soil fertility and affect crop yield. Excavation and removal of soil from isolated patches of land creates low lying and elevated degraded areas which disrupts normal crop cultivation pattern. Natural gamma-ray spectrometry (NGS) can be used as a non-destructive and rapid geophysical sensing method, for identification and delineation of areas with suitable soils. During this work brick kiln areas were visited to understand soil's availability and extraction pattern. NGS measurements of samples from soil profiles were carried out to find if gamma-ray intensities varied with soil clay content. Soil texture and plasticity of the same samples were obtained following standard testing procedures. Winkler and Plasticity charts were used to assess suitability of the soils. A strong linear relationship between gamma-ray potassium (K) intensity and clay contents of soil profile samples (R2 = 0.88) was observed. NGS based devices can be used to scan soil samples rapidly and log shallow depth boreholes in grid sampling design. The gathered spectral gamma-ray data can be then used to predict and generate high resolution 3D models of soil properties, based on which resource areas of suitable soils can be delineated for long term soil extraction without affecting cultivated areas. This will help in delineating areas restricted for soil extraction, which will not only make soil mining sustainable but also address soil conservation by setting aside large cultivated fertile soil areas untouched. Adopting NGS methods will prevent unsystematic removal of fertile soil and creation of degraded lands. This will ultimately result in efficient soil resource management. [Display omitted] • Natural Gamma-ray spectrometry (NGS) scanners can quickly assess quality of soil for brick and earthenware manufacturing. • NGS logging of shallow-depth boreholes in alluvial soils can help generate layer wise map and 3D models of soil resources. • Suitable areas can be demarcated using soil information for long term soil extraction without affecting cultivated areas. • Sustainable extraction of soil resources can be attained by Intervention of Natural Gamma-ray spectrometry (NGS) method. [ABSTRACT FROM AUTHOR]

The dynamic structural response of a vertical pile port platform under the action of irregular wave loads considering soil-structure interaction is studied. Deck displacement and bending moment on the piles were evaluated for a set of structural, hydraulic, and geotechnical parameters. Static structural analyses with the maximum base shear produced by wave loads and dynamic time-history analyses are performed to study the effects of dynamic amplification on the structural response of the platform. Two types of waves are analyzed, regular and irregular, to analyze the amplification effects due to the superposition of a wave train of different periods in the case of irregular waves. Cases with fixed base support and non-linear spring-modeled soil are considered to evaluate the effect of considering a flexible base for the platform. Eight structures composed of a different number of piles and with different heights were analyzed. Six wave conditions with different characteristics are used, varying the wave period and mean water height. Two sandy and two clayey soil profiles are considered with different densities and consistency. The results show that resonance effects associated with dynamic loading and small-period wave superposition in cases of irregular waves significantly affect the response. Furthermore, considering a flexible base tends to decrease the response for short wave periods, concluding that, in most cases, for wave periods close to 5 s, considering a fixed base model overestimates the response. • A transparent port platform with vertical piles under wave loads is studied. • Effects of dynamic loading, irregular waves and flexible base modeling are analyzed. • Resonance effects are not represented in a study with regular waves. • Resonance effects due to dynamic loading and irregular waves are significant in the displacement and bending moment response. • The use of a fixed base overestimates the bending moment response of the structure. [ABSTRACT FROM AUTHOR]

A three-dimensional numerical analysis is conducted on a group pile adjacent to a deep multi-strutted excavation in a naturally occurring soil profile comprising both cohesive and non-cohesive layers. The contrasting soil layers affect the soil stiffness, strength, and deformation characteristics, thereby impacting the load transfer mechanism within a pile group. The primary aim of this study is to specifically understand how the presence of a non-cohesive soil layer within a predominantly cohesive soil profile, affects the behavior of a pile group during excavation. By systematically varying the position and thickness of the soil layers, the analysis highlights the significance of considering the actual soil profile's inherent heterogeneity rather than assuming a homogeneous clay layer. 19.2% and 17% deviations respectively are observed for pile group settlement and lateral deflection when a homogeneous clay layer is considered instead of the natural soil profile. The findings also show that the position of the non-cohesive soil layer within a predominantly clay soil profile is more critical than its thickness in determining the pile response to excavation-induced changes. The non-cohesive soil layers within the excavation depth, significantly influence the lateral and axial pile behavior, while those below the final excavation depth have a limited impact. A theoretical simplified framework is proposed for the preliminary assessment of the excavation-induced effect on an adjacent pile group. This simplification helps minimize the initial calculation time and effort while capturing the significant factors affecting the pile group behavior near the excavation. [ABSTRACT FROM AUTHOR]

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

Comparison of the carbon (C) stocks among different soil orders allows us to explore the role of various soil characteristics in long‐term C storage and their vulnerabilities. This study quantified and compared the accumulation rates of soil organic carbon (SOC) fractions (in 0–60 cm soil profile) in an Alfisol of Malda (25°27′33.9″N, 88°19′10.2″E) and an Entisol of Cooch Behar (26°09′62.7″N, 89°53′51.7″E) districts of West Bengal, India. We noticed a greater level of SOC (0–60 cm depth) in the Alfisol than the Entisol as the former soils were clayey in nature (fine textured) which provided the maximum stabilization of SOC compared to the Entisol (sandy textured). However, the storage of C fractions showed some peculiar results. The concentration of mineral‐associated carbon (Min‐C) was more or less similar in both the soil orders, but its stock was maximum in the Alfisol. While in the Entisol, permanganate oxidizable carbon (POX‐C) and particulate organic matter carbon (POM‐C) stocks recorded maximum among all the studied depths. A positive relation of SOC fractions and stocks with clay (r2 = >0.500 in the Alfisol; r2 = >0.700 in the Entisol) indicated the importance of finer fractions in profile storage of C. Min‐C contributed to SOC of about 75%–85% followed by POM‐C (3.27%–17.87%) and POX‐C (2.57%–4.22%). Higher stratification of SOC and POX‐C and POM‐C fractions was observed in Entisol; while in Alfisol, stratification of Min‐C was greater. Overall, this research demonstrated that the Alfisol has a greater potential in stabilizing Min‐C than the Entisol with POM‐C and POX‐C and the distribution of these fractions varied as per its stabilization. [ABSTRACT FROM AUTHOR]

Herbicides are one of the most widely used agrochemical classes around the world. They help farmers to protect their crops against weeds. However, they can move through the soil profile polluting water resources and adversely affect human health. Groundwater is an important source for the production of drinking water in many places of the world and the presence of pesticide residues in groundwater is a serious threat to the health of consumers of drinking water. In this work, the behavior of two herbicides Atrazine and Trifluralin were study in an agricultural soil: Alhue soil and this soil modified whit clay (Kaolinite) and organic matter (Humus). The original soil and modified soil samples were characterized by their physicochemical properties: pH, EC, OC and texture. The analytical method was optimized for the quantification of Atrazine and Trifluralin by High Performance Liquid Chromatography (HPLC). The contact time, adsorption/desorption isotherms, persistence of both compounds in the soil samples and modified soil samples with clay and/or organic matter was studied. In general, all sorption curves for Trizine and Trifuralin in the modified soil samples were similar with relatively low adsorption for Trifuralin indicating that the soil modifications were not significant. The kinetic of sorption process was described by Elovich model. Both herbicides present a low Koc value, however, they present different types of adsorption, being for Atrazine a moderate adsorption and for Trifluralin a weak adsorption, which implies that both herbicides could be distributed in bodies of water as they are not fixed by organic matter. However, it should be noted that Atrazine presents higher Koc values than Trifluralin in all soil samples, which could mean that Atrazine would be less bioavailable than Trifluralin. Values obtained in the Pearson correlation of CO (%) and % of clay are expected since, when observing the results obtained in the Kd parameters for soils modified by both herbicides, they show that the higher the % of the physicochemical parameter, the higher the adsorption of the compound by the soil. The persistence of the pesticides showed that with both the addition of Kaolinite and Humus to the soil increases the half-life time for both herbicides. The results of the GUS index showed that both Atrazine and Trifluralin would be classified as leachable compounds in all soil samples. [ABSTRACT FROM AUTHOR]

This paper presents the results of in-situ testing of two integrated pile-columns of a partially demolished bridge located in Auckland, New Zealand. A series of tests involving lateral monotonic pushover and subsequent dynamic free vibration snapback tests were used to quantify the variation in the stiffness and damping behaviour of the pile-column specimens over a range of lateral load levels. Each testing sequence consisted of incrementally increasing peak monotonic loads followed by the dynamic snapback, with a series of varying peak loads at the end of the testing sequence to evaluate the influence of loading history on the monotonic and dynamic response. The secant stiffness between the monotonic pushover tests performed to the same loading levels before and after the maximum load was applied, reduced by up to 40% in both the pile-columns, primarily due to soil gapping effects, highlighting the significant potential softening of the system prior to pile or column yielding. Progressive reduction in the damping of the system during each snapback test was evident, due to the varying contributions of different energy dissipation mechanisms, and the level of damping varied depending on the peak load applied. These results highlighted the significant influence of soil gapping and nonlinearity on the dynamic response of the system. Numerical models were developed in the open source structural analysis software OpenSeesPy using a Nonlinear Beam on Winkler Foundation approach to further investigate the response of the pile-columns. Models of both the pile-columns using existing p-y curves for clay soils showed good agreement with the experimental data in loaddisplacement, period and snapback acceleration time histories. Sensitivity analysis showed that the surface soft clay layer had a significant effect on the lateral response and dynamic characteristics of the model, reinforcing the need for good characterisation of the near surface soil profile to capture the behaviour of the system. [ABSTRACT FROM AUTHOR]

We explore the soil physical characteristics in wetland of Barito Delta from primary data of soil sample and electrical resistivity measurement with the support from some secondary data. We also estimate saturated hydraulic conductivity (Ks) in Barito Delta from soil physical characteristics applying Saxton and Rawls (1986) and Weynants et al. (2009). Soil texture profile is determined from interpolation of soil fraction in each layer applying Bayesian statistics to analyze soil physical characteristics in the landforms of Delta. Clay is the dominant soil fraction in the soil of Barito Delta. Clay fraction percentage decrease along the depth of soil profile as it reaches fine sand particles deriving from ancient sedimentation from the past. It is an opposite with soil organic matter content that has contrast value from 1st to 2nd soil depth, but a few discrepancy from 3rd depth to downward direction. The content of clay in the soil depends on the sedimentation activity in the landform. Clay is dominant soil particle in the Delta; in case, it is in flat area and there is no intensive of sea water sedimentation such as in Basin of Peat Anticline and Natural Levee. In more than 2 m depth of soil, loamy sand and silty clay textures are mostly in the landform that is influenced by sea water activity, while by river water is clay loam. Ks values from Saxton and Rawls (1986) are close to Ks values from the measurement of previous studies. Ks values are generally small in Barito Delta that is mostly ranging from 1.10−7 to 2 m s−1. Ks values are larger following the depth of soil profile. The values of Ks are smaller in Basin of Peat Anticline and Natural Levee than in Tidal Flat and Beach Ridge. It is because both landforms have clay as dominant soil particles. [ABSTRACT FROM AUTHOR]

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

Soil shrinkage during the drying process (water stress) is one of the main issues in expansive soils of paddy fields. It occurs due to decrease in soil water content, resulting in changes in soil volume and the geometry of pores, leading to the formation of cracks and higher water loss. The aim of this study was to assess the shrinkage characteristic curve and pore size of paddy soils to determine the shrinkage -swelling behavior in Guilan province, Iran. 120 soil samples were collected from the study area. Pore size was determined using soil moisture retention curve (SMRC). It was established by plotting the soil water content (θ) versus the corresponding matric suction (h), and the shrinkage curve by plotting the void ratio (e) against the moisture ratio (υ). The suction-pore relationships were also determined. Furthermore, the geometric factors indicating the change in vertical (subsidence) and horizontal (crack) volume of the soils were determined and varied from 1.23 to 2.53, indicating that the vertical change in soil volume is predominant. The zero, residual and proportional shrinkage phases accounted for less than 2 %, 8–38 %, and 61–91 % of the total soil volume change, respectively. The shrinkage capacity of the soils ranged from 0.52 to 1.37. Cation exchange capacity and clay content were identified as the most important factors affecting soil shrinkage properties. In general, the studied paddy soils have great potential for swelling- shrinkage and cracking during the drying process due to the large percentage of expandable clays and the medium to fine pores. The resultant cracks negatively affect crop yield by damaging plant roots and increasing water losses through the soil profiles. • Guilan paddy soils have a great potential for swelling- shrinkage and cracking during drying process. • Predicting indicators related to shrinkage curve can be an effective way to manage soil and water. • Wetting and drying intensity in paddy soil had a greater impact on soil shrinkage. • The cation exchange capacity and clay were the most important factors affecting the soil shrinkage properties. [ABSTRACT FROM AUTHOR]

Soil suction–based analyses are paramount to proper design of foundations in expansive soils, yet availability of field soil suction profiles from direct measurement is limited. A method was developed, using directly measured suction profiles obtained from sites across the US, by which routine geotechnical tests can be used to estimate soil suction to expand the database for estimation of field suction profiles. Herein, the expanded database is used to develop best-estimate clay soil suction envelopes for boundary conditions associated with covered or uncovered ground surface subjected to natural climatic surface flux. Where appropriate for site conditions, the proposed soil suction profile envelopes can be used with any suction-based heave/shrinkage analysis. Key features of the field suction envelopes, consistent with current popular approaches, include climate-dependent estimates for equilibrium suction at depth, depth to equilibrium (stable) suction, and variation in soil suction at the ground surface. Comparisons to existing soil suction envelope recommendations are made. Finally, a limited number of cases of developed/irrigated sites are presented for comparison to soil suction profiles obtained for natural climatic surface flux conditions. [ABSTRACT FROM AUTHOR]

Static and dynamic behavior of above-ground steel storage oil tanks resting on end bearing piles or stone columns are studied and analyzed using ADINA (2019) program. The studied soil profile is an upper soft clay soil layer, followed by an extended dense sand layer. The main purpose of this research is to explore to what extent stone columns can be used as an effective alternative to concrete piles under steel storage tanks. Therefore, many three-dimensional numerical models are conducted to analyze and study the performance of such tanks in both static and dynamic cases. Ten of the studied cases are steel tanks resting over stone columns with different numbers and properties. On other hand, one model studied the behavior of steel tank resting on large diameter concrete piles. Results indicate that stone columns can be used instead of end bearing piles as long as the computed settlements are safe. In addition, stone columns are behaving better than concrete piles in decreasing of hoop stress in tank shell. It is also noticed that stone columns with high elastic modulus are effective in reducing the sloshing height of the oil surface during earthquakes. [ABSTRACT FROM AUTHOR]

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

Public concerns over environmental protection have increased after Fukushima accident. The soil-plant transfer factor (Fv) is a critical parameter for environmental risk assessment. 137Cs Fv values determined in acid Brazilian soils could be two orders of magnitude higher than Fv values measured in soils affected by the Chernobyl accident. This paper studied the behaviour of 90Sr in Brazilian soils where very few 90Sr Fv data is available. All classes of studied soils (Ferralsol, Acrisol and Nitisol) showed that more than 80% of total 90Sr in soils remains potentially mobile, mainly at the bioavailable phase, more than 2 years after soil contamination in an experiment conducted in lysimeters. Higher 90Sr Fv for maize and cabbage was observed in the acid soils with low content of exchangeable Ca, lower Fv values occurred at Nitisol, the subtropical soil type. It seems that the behaviour of 90Sr in these soils are mainly controlled by ionic competition mechanisms occurring for root uptake and sorption sites, with stable Sr and major nutrients (Ca, Mg and K). The mineralogy also seems to play a relevant role, since goethite rich clay soil presented 90Sr Fv values higher one or two orders of magnitude than 90Sr Fv values observed at clayed soil goethite rich with trace of vermiculite, for all studied crops. The high rate of 90Sr migration down the soil profiles observed for the studied soils during the 2 first years after contamination suggests a high rate of transfer to groundwater, even transfer to leafy crop group can be also a relevant pathway. In the present study, maize, among other plant species, presented the lowest Fv values, even when compared with maize cultivated in temperate soil. Our results suggest that stable Sr may not be a very good analogue of 90Sr for determining plant Fv values: geometric mean of stable Sr Fv for maize was Fv maize = 6.3E-1 ± 2.1E0 (n = 8) and for 90Sr was Fv maize = 1.8E-2 ± 2.5E0 (n = 16), geometric mean of stable Sr Fv for cabbage was Fv cabbage = 1.4E0 ± 3.9E0 (n = 17) and for 90Sr was Fv cabbage = 7.9E-1 ± 4.4E0 (n = 18). [Display omitted] • Transfer of 90Sr and stable-Sr was studied in Brazilian soils. • 90Sr in Brazilian soils (Ferralsol, Nitisol, Acrisol) had a high potential mobility. • Mineralogy plays a key role in determining 90Sr availability for plant uptake. • Stable-Sr is not a good analogue for 90Sr plant uptake. • A high rate of 90Sr migration down the soil profile was observed. [ABSTRACT FROM AUTHOR]

Calcic vertisol is a typical kind of low-yield field with a total area of about 4 million hm2 in China. Calcareous concretion with particle size larger than 2 mm has been one of the representative characteristics of calcic vertisol. The limitation of soil available water is an important reason for crop failure in this region. Therefore, the curve of soil water retention dominates the estimation of available water content. However, most studies focused on the effects of calcareous concretion on soil water retention of calcic vertisol mainly under laboratory conditions. It is lacking that under field conditions. In this study, both field surveys and laboratory experiments were conducted to explore the effect of calcareous concretion distribution in 0-1 m soil profile on soil water retention. Firstly, the spatial distribution of calcareous concretion was investigated in the study plot with 150 m length, 50 m width, and 1 m depth. After then, soil profiles (0-1 m soil depth) were chosen to divide into 5 layers with a 20 cm interval. Disturbed and undisturbed soil samples were collected in each layer. Physicochemical properties were evaluated to measure the distribution of soil particle size, size and content of calcareous concretion, bulk densities of soil, and calcareous concretions. Meanwhile, the curves of soil water retention were determined using high speed centrifuge. A pressure plate method was conducted to measure water retention curves in calcareous concretion. The results showed that the mass contents of clay, silt, and sand were 30.56%-39.75%, 39.88%-45.34%, and 18.67%-24.45%, respectively, which belonged to silty clay soil in the classification standard of the United States Department of Agriculture (USDA). Clayey particles decreased, but sandy particles increased significantly with the increase of soil depth. Calcareous concretion was mainly distributed in the soil depth of >20-100 cm, where the content and size increased as soil depth increased. Calcareous concretions content in the surface soil (0-20 cm) was very low (with mass content 0.02%), where only a few calcareous concretions of 2-5 mm were discovered. The maximum content of calcareous concretion was detected at > 80-100 cm (up to 11.42%), where the calcareous concretion content was 8.04% in the size of >8-30 mm. Soil bulk density ranged from 1.23-1.61 g cm-3. The densities of calcareous concretions were 2.01, 2.21, and 2.23 g cm-3 with the size of 2-5 mm, >5-8 mm, and >8-30 mm, respectively. Soil bulk density increased along with the calcareous concretion content increasing. Water retention curves of soil and calcareous concretion were well fitted by the van Genuchten model, with the determination coefficient larger than 0.95. The saturated water content of surface soil (0-20 cm) was significantly higher than that of 20-100 cm soil. Nevertheless, the Gravitational-water content in the surface soil (0-20 cm) was much larger than that in the soil of > 20-100 cm, which was related to macropores formed during tillage. In the subsurface (>20-100 cm), soil gravitational-water content and available water-holding capacity increased with the increase of soil depth, but the field capacity and wilting point decreased. Calcareous concretion maintained a non-negligible amount of water, 0.25, 0.22, and 0.20 cm3 /cm3 in the particles with the size of 2-5 mm, >5-8 mm, and >8-30 mm, respectively. But the water-holding capacities of calcareous concretion were significantly lower than that of soil. The effects of calcareous concretion on water-holding capacity mainly occurred in the subsurface soil. Soil saturated water content, field capacity, and wilting point decreased with increasing calcareous concretion. Interestingly, calcareous concretion content was positively correlated with the soil sand content, but negatively correlated with the soil clay content. Calcareous concretion can bind soil particles together to prevent sand weathering, and thereby effectively improve soil texture. More calcareous concretion led to higher sand contents, and thus increased the available water-holding capacity in soil. This finding can provide a theoretical basis to accurately assess the soil water-holding capacity in calcic vertisol for precision irrigation and high crop productivity. [ABSTRACT FROM AUTHOR]

Infiltration is one of the most important hydrological process through which water enters the soil surface and plays a significant role in controlling soil water storage, crop yields, irrigation efficiency and solute entry into the soil profile. In agriculture fields, generally, the top soils are enriched with high organic matter and clay, particularly in black soils that promotes sorption, biological degradation and transformation of contaminants. During the process some of the chemicals applied to farm land, move down with the deep percolating water from the root zone and there are likely chances to pollute the underlying ground water. Such instances are reported by locals in areas dominated by black soils of Malaprabha command area. In order to understand the extent of groundwater contamination through chemical fertilizers, insecticides and manures, two agricultural plots (sugarcane and banana plantation) have been identified in parts of Malaprabha command area covering parts of Saundatti, Ramdurg (Belagavi district) and Nargund taluks (Gadag district). Hydraulic properties such as infiltration and hydraulic conductivity were determined in the field. Soil samples were collected and analysed in the laboratory for texture and porosity. The study indicated that the soils of the region are layered in structure. Further, it is noticed that the coarse textured loamy soil is present below the fine textured soils (such as silty loam or clayey loam). Due to the presence of fine soils at the top, the irrigated water get accumulated and the evaporation takes place relatively faster and results in the accumulation of excess salt. It is also noticed that the layered soils have obvious effects on solute transport and salt accumulation in the clay rich soil layer at the interface. The average salt accumulation (Total Nitrogen) observed in the study area within soil profile is 18.7g/kg. The maximum salt accumulation (21.38 g/kg) occurred in the top layer of sugarcane plots followed by banana plantation (19.85 g/kg). It is also noticed that there are remarkable changes in the interlayered soils with reference to water infiltration characteristics and salt leaching intensities. Study revealed the fact that the properties of the soil profile with a silty loam interlayer is better than with a silty clay loam interlayer. [ABSTRACT FROM AUTHOR]

In this theoretical work, a dual-frequency polarimetric method is proposed for measuring moisture profiles in the topsoil up to 0.30 m thick. A case of measuring soil moisture profiles, which monotonically changes with depth, during 37 days after irrigation is considered. Original values of backscattering coefficients are calculated by the Oh model and by the small perturbation method at frequencies of 5.4 GHz and 435 MHz, respectively. In these calculations, we used measured moisture profiles and spectroscopic refractive mixing dielectric model of non-saline mineral soil with a clay fraction of 9.1%. Soil moisture profiles are retrieved by solving the inverse problem, the cost function of which is constructed based on the co- and cross-polarized ratios, calculated at two frequencies for the measured and modelled soil moisture profiles. An exponential function is used as a modelled soil moisture profile. It is shown that the standard deviation between the retrieved and measured soil moisture values in the surface layer 0.30 m thick appears to be ≤0.02 m3 m−3 (theoretical limit), and the determination coefficient is 0.881. The study shows a promising path towards developing multi-frequency radar systems for remote sensing of soil moisture profiles using satellites-based and unmanned aerial vehicles air-based platforms. [ABSTRACT FROM AUTHOR]

The main aim was to conduct a pilot study of diagnostic characteristics of soils on the territory of the Strandzha mountain and their classification according to WRB requirements (2006, 2007), including microbiological activity in stands with different tree composition. A total of seven soil profiles were studied. Soil and litter samples were collected from territories where it was previously known that the soils were with a clay - enriched subsoil (defined as Luvisols, Alisols and Zheltozem-podzolic soils). Soil classification indicators have been investigated according to the requirements of World Reference Base for soil resources. Five of the soil profiles were classified as Lixisols and two as Acrisols. On the second taxonomy level for Lixisols applied prefix qualifier - haplic and suffix qualifier - hypereutric. For Acrisols applied prefix qualifier haplic. Lixisols and Acrisols were established on the territory of Strandzha Mountain for the first time in oak and beech stands. Analysis of the heterotrophic microflora's total number and the structure of the microbial communities of two soil profiles was carried out. The different tree species and the period of litterfall affect the number of microbocenosis and the distribution of microbial groups in it. In the beech stand (Fagus orientalis Lipsky), the processes of enhanced transformation of easily degradable soil organic matter (SOM) predominated, compared to oak stand (Quercus frainetto Ten. and Quercus petraea Liebl,) where more advanced processes of transformation of SOM were observed. [ABSTRACT FROM AUTHOR]

Specific red clayey soils on the eluvium of limestone, which are traditionally associated with Mediterranean terra rossa, have been described in the Cape Martyan Reserve in south Crimea. Though such soils are well studied, there are several open questions related to the genesis of the red-colored soils of Cape Martyan. Many researchers consider them as surface paleosols combining features formed in the previous epochs and those of current processes. Based on the analyses of the physical and chemical properties, composition of the clay fraction, and micromorphological features of red soils, we have shown that almost all soil-forming processes, except for the long-term dissolution of calcareous rocks and rubification of residual silicate clay, are slightly pronounced, because the compact clay parent material is low sensitive to pedogenesis. Evidences of the fact that past pedogenesis differed from the modern one are almost absent in the soil profiles, which corresponds to the data on the climate stability in this area since the Pliocene. The studied soils may be assigned to Vetusols—ancient soils formed under relatively constant bioclimatic conditions. [ABSTRACT FROM AUTHOR]

BACKGROUND Residual herbicides are an important component in many weed control strategies. Their herbicidal activity depends on their fate in soil, with respect to the required concentration for weed control in space and time. In this study, the effect of weather conditions on sulfosulfuron fate in soil, following pre‐planting incorporation, and the predicted control efficacy of Egyptian broomrape in tomato, were analyzed for two sites using simulations in Hydrus‐1D modeling software. Simulated concentration was compared to measured data from field experiments. RESULTS: Model evaluation against measured data from two fields, with weakly alkaline clay soils, showed high correlations between simulated and measured sulfosulfuron concentrations (r = 0.98 and 0.89). The ratio of measured to simulated concentration was relatively low (1.03) at the top 10‐cm layer, in which the mean measured concentration was high (29.6 ng g−1). This ratio was higher (12.5) at the 30–60 cm depth, in which the mean measured concentration was lower (0.3 ng g−1). Simulations of sulfosulfuron fate in each site, using weather data from the years 2009 to 2019, revealed substantial variations in transport patterns. Thirty days after treatment, 16 out of the 22 years simulated for the two sites (11 at each site) resulted in concentrations lower than the critical value for Egyptian broomrape control throughout the soil profile. The data indicates that variation in sulfosulfuron fate is mainly due to differences in the cumulative precipitation. According to simulation results, cumulative precipitation above 20 or 10 mm during the first 10 or 20 days after treatment, respectively, is expected to reduce the efficiency of broomrape control. CONCLUSION: Considering weather effects when planning herbicide application could optimize herbicide use efficiency. A decision‐support tool is presented, whose factors are the time gap and precipitation amount between sulfosulfuron application and tomato planting. [ABSTRACT FROM AUTHOR]

A series of 3D finite element (FE) analyses were performed to estimate the peak penetration resistance of spudcan foundations in sand over clay soil profiles. Elasto-perfectly plastic models following Mohr–Coulomb and Tresca failure criteria were used for sand and clay layers, respectively. The coupled Eulerian–Lagrangian (CEL) approach was used to simulate the large deformation in soil that occurs during the spudcan penetration. The performance of the numerical model was validated against centrifuge test results. A parametric study with a broad range of strength parameters for sand and clay was performed. The numerical results were used to assess the influence of sand thickness (Hs), the diameter of spudcan (D), friction angle of sand, and undrained shear strength of clay (su). A wide range of su was utilized to predict the resistance both of the soft and stiff clays. The calculated peak resistances are compared with a published analytical model. It is demonstrated that the model highly overestimates the peak resistance for stiff clays, most likely because it was developed specifically for soft clays and, therefore, does not account for the influence of su. One of the parameters of the model is revised to account both for su. Comparisons highlight that the modified model is able to capture the simulated peak penetration resistance for both soft and stiff clays. [ABSTRACT FROM AUTHOR]

This paper tests the hypothesis that the soil organic carbon (OC), total nitrogen (Nt), nitrate-N and ammonium-N in forests are significantly different from the same properties in arable soils, under similar relief, geology, climate and heavy-clay soil conditions (phaeozioms). Such soils are largely spread in the world. Four pairs of soil profiles 1.5 m deep were carried out in both forest soils and arable soils. The different environmental conditions produced modifications in OC, Nt and other related properties. OC content and Nt content for the first 0.5 m depth soil strata are distinctly significantly higher in forest soils versus arable soils. Soil NO3–N and NH4–N contents present non-significant differences for the same depths in the two land uses. OC, Nt and NH4–N contents are directly and highly significantly correlated for all soil layers. Measurements of OC and N from topsoil are not sufficient for a thorough evaluation of the environment. Afforestation is a measure to increase soil carbon sinks. The findings might be extrapolated to countries with similar environment. [ABSTRACT FROM AUTHOR]

Measuring soil water-physical properties is laborious, time-consuming, and expensive. That provokes a lot of scientists to estimate them which action is troubled by the usage of different soil texture classification systems. The study proposes a rapid, reliable, and universally applicable methodology for soil textural transformations between different classification systems. The method of discrete mathematics is applied to make the conversion of particlesize classes from the Kachinsky system, which is used in Bulgaria to the International systems. Three different data sources were used to determine the water-physical properties of soils from textural data - 376 soil profiles from Bulgaria, extraction from the SoilGrids system for the Plovdiv district in Bulgaria and data from CanSIS/NSDB database. The relationship between the dependent variables field capacity (FC), wilting point (WP) and bulk density (BD), and independent variables sand, silt, and clay soil content was sought in the form of a regression equation. The applied stepwise regression procedure produces a close dependence between the soil texture and its water-physical properties. [ABSTRACT FROM AUTHOR]

Aim: Forest soils contain large amounts of terrestrial organic carbon (C), but the formation pathway of soil organic C (SOC) remains unclear. Recent evidence suggests that microbial necromass is a significant source of SOC, yet a global quantitative assessment across the whole soil profile is lacking. We aimed to assess the vertical distribution and control of microbial‐derived SOC in forest soils. Location: Global forests. Time period: 1996–2019. Major taxa studied: Soil microbial necromass carbon. Methods: We evaluated the proportions of fungal and bacterial necromass C in total SOC in the litter layer, O horizon soil, and various depths of mineral soil in forests using microbial biomarker (glucosamine and muramic acid) data. Results: The total microbial necromass C increased significantly with soil depth, ranging from 30% of SOC in O horizon soil to 62% of SOC in mineral soils below 50 cm. However, only bacterial necromass C followed this increasing trend with soil depth; fungal necromass C showed little variation across the whole soil profile. Higher fungal and bacterial necromass C was observed in soils with lower C/N ratios and smaller aggregate sizes. Soil C/N ratio and microbial biomass C dominantly determined microbial necromass C in surface soil (above 20 cm), but soil clay content was the primary factor in subsoil (below 20 cm). Main conclusions: Microbial necromass C accounted for high percentages of the total SOC in forest soils (particularly at depths >20 cm), but its long‐term stabilization may be governed by different mechanisms at different soil horizons. Substrate quality regulates microbial activity and then controls biomass turnover in surface soil, while aggregate occlusion facilitates mineral protection of microbial necromass C in subsoil. These differential controls of microbial‐derived organic C could be applied in Earth system studies for predicting soil organic C dynamics in forests. [ABSTRACT FROM AUTHOR]

Soil properties in three rain forest types and six different elevations (921, 1173, 1317, 1556, 1727 and 1932 m above sea level) were studied at Mount Alab, Sabah. The chosen study site consisted of soils derived from sedimentary rocks of the Crocker Formation aged from Late Eocene to Early Miocene. Results of this study showed that soils with difference in elevation demonstrated considerable variations in term of morphological and physicochemical properties depending on the nature of the parent materials. At the highest elevation, the soil profile presented with a thin surface organic layer. On the other hand, the soils changed from Inceptisols to Ultisols with decreasing elevation. All soils were moderately acidic with an abundance of sand in these soil profiles due to the dominance of sandstones in their parent materials. Clay fraction of these soil profiles was dominated by clay-sized quartz while illite, kaolinite, interstratified illite-vermiculite, gibbsite and vermiculite were present in low or minor amounts. The chemical properties of the soils were significantly affected by topographical positions. The highest value of total organic carbon and total nitrogen were obtained at the summit, whereas, toeslope had relatively more exchangeable calcium and aluminium. Therefore, soil quality was better at higher topographical positions in this study. [ABSTRACT FROM AUTHOR]

Long‐term soil management can produce anisotropic impacts on soil structure, resulting in differences in horizontal and vertical hydraulic conductivity. As limited data exist on these impacts, this study provides a broad‐scale assessment across 764 soil profiles under arable and grassland use in northern Germany (Federal State: Schleswig‐Holstein). The soils were sampled in the four geological regions: Weichselian glacial region, the sandy outwash region (Lower "Geest"), the Saalian glacial region (Higher "Geest") and the marshland with alluvial deposits. Saturated hydraulic conductivity (Ks, either in a horizontal (Ks_h) or vertical direction (Ks_v)) and the pore‐size distribution were determined on undisturbed soil samples (100 cm3), whereas the grain size distribution was analysed on disturbed samples from the major soil horizons. This research work presents Ks_h and Ks_v values for representative soil types of the four geological regions down to a depth of 60 cm. Irrespective of the parent material in the four geological regions, arable soils showed a pronounced anisotropy of Ks in the horizontal direction. However, Ks_h and Ks_v also showed a high variability across the geological regions from approximately 1 to 800 cm d−1, whereas the ratio of Ks_h to Ks_v ranged from 0.1 to 500. In the marshland (dominated by Gleysols), the direction‐dependent values were superimposed by sedimentation processes of the marine material and/or structural development processes such as vertical shrinkage or bioturbation processes. Under grassland, the topsoils primarily indicated horizontally anisotropic flow conditions. In the "Geest" area with a high share of dairy farming, both top‐ and subsoils displayed the highest horizontal anisotropy values, indicating the stress‐induced formation of a platy structure caused by trampling, grass harvesting or slurry application with heavy machinery. Soil type (e.g., Stagnic Luvisols, Stagnosols or Anthrosols) and horizon‐dependent horizontal anisotropy were also more pronounced in arable than in grassland subsoils. Highlights: Hydraulic conductivity in arable subsoils shows mostly horizontal behaviour.Hydraulic conductivity in grassland topsoils shows mostly horizontal behaviour.The anisotropic degree and its direction depend on land use type and clay content of the soils. [ABSTRACT FROM AUTHOR]

Purpose: Sediment accumulation has been and continues to be a significant threat to the integrity of the playa wetland ecosystem. The purpose of this study was to determine the vertical depth to the clay soil layer (Bt horizon) and thus to calculate the thickness of sediments accumulated in playa wetlands. Materials and methods: This study used the electromagnetic induction (EMI) survey method, specifically EM38-MK2 equipment, to measure the vertical depth to the clay soil layer at the publicly managed wetlands in the Rainwater Basin, Nebraska, USA. Results and discussion: The results indicated that the depth to the clay soil layer ranges from 21 to 78 cm (n = 279) with a mean sediment thickness of 39 cm. The annual sediment deposition rate since human settlement in the 1860s was calculated to be 0.26 cm year−1. The results provided science-based data to support future wetland restoration planning and the development of decision support tools that prioritize conservation delivery efforts. Conclusions: Our research confirmed that the EMI technique is effective and efficient at determining the depth to the Bt horizon for playa wetlands. Additionally, these results supported previous studies and continue to indicate that a large amount of sediment has accrued in these playa wetlands within the Rainwater Basin area since settlement. Wetland restoration ecologists can use this information to prioritize future wetland restoration work that intends to remove culturally accumulated sediments above the clay soil layer. These findings provided a contemporary summary of wetland soil profile information that is typically used to develop restoration plans. This research also filled the critical knowledge gap about the thickness of the upper soils and the depth to Bt in publicly managed wetlands. [ABSTRACT FROM AUTHOR]

Recent discoveries of polyhalite (K2SO4.MgSO4.2CaSO4.2H2O) in the UK provide an alternative to conventional fertilizer sources. This work investigated the interaction of polyhalite, commercially known as POLY4, with soil using leaching columns. Different physical forms of polyhalite (powder, crushed rock and granules) were compared to potassium chloride (KCl) for the movement of potassium, calcium, magnesium and sulphur (as sulphate) through the soil profile using 19.7 L of water, equivalent to 4,500 mm rainfall. The nutrients from polyhalite were found to be available at 30 cm depth, with calcium showing signs of interacting with the soil clay particles to release cationic nutrients. Polyhalite granules showed the greatest release of sulphate, magnesium and calcium as a proportion of the additional nutrient with 127%, 71% and 102%, respectively leached. For potassium, all forms of polyhalite had greater release than KCl (powder = 58%; granules = 86%; crushed rock = 57% and KCl 16%). Nutrients from polyhalite and those mobilized from soil interactions are present in soil solution indicating availability for plant growth. [ABSTRACT FROM AUTHOR]

The aim of the study was to analyze the diagnostic properties of soils on territory of Training and Experimental Forest Range (TEFR) "Petrohan" in order to classify them according to the modern requirements of World Reference Base for soil resources. Seven soil profiles were studied. Soil samples were collected from territories in which it was known that the soils are with a clay - enriched subsoil (Luvisols). Soil classification indicators have been investigated according to the requirements of World Reference Base for soil resources. Five soil profiles were classified as Acrisols and two as Lixisols. On the second taxonomy level for Acrisols apply Vetic prefix qualifier. Lixisols were identified as Vetic and Haplic. Acrisols and Lixisols were established on the territory of the TEFR „Petrohan" in beech forests of the temperate climate zone. We assume that specific weathering processes and acidifying effect of beech forests have been playing a key role for Acrisols and Lixisols formation. [ABSTRACT FROM AUTHOR]

The spatial and temporal controls of preferential flow (PF) during infiltration are still not fully understood. As soil moisture sensor networks allow us to capture infiltration responses in high temporal and spatial resolution, our study is based on a large-scale sensor network with 135 soil moisture profiles distributed across a complex catchment. The experimental design covers three major geological regions (slate, marl, sandstone) and two land covers (forest, grassland) in Luxembourg. We analyzed the responses of up to 353 rainfall events for each of the 135 soil moisture profiles. Non-sequential responses (NSRs) within the soil moisture depth profiles were taken as one indication of bypass flow. For sequential responses maximum porewater velocities (vmax⁡) were determined from the observations and compared with velocity estimates of capillary flow. A measured vmax⁡ higher than the capillary prediction was taken as a further indication of PF. While PF was identified as a common process during infiltration, it was also temporally and spatially highly variable. We found a strong dependence of PF on the initial soil water content and the maximum rainfall intensity. Whereas a high rainfall intensity increased PF (NSR, vmax⁡) as expected, most geologies and land covers showed the highest PF under dry initial conditions. Hence, we identified a strong seasonality of both NSR and vmax⁡ dependent on land cover, revealing a lower occurrence of PF during spring and increased occurrence during summer and early autumn, probably due to water repellency. We observed the highest fraction of NSR in forests on clay-rich soils (slate, marl). vmax⁡ ranged from 6 to 80 640 cm d -1 with a median of 120 cm d -1 across all events and soil moisture profiles. The soils in the marl geology had the highest flow velocities, independent of land cover, especially between 30 and 50 cm depth, where the clay content increased. This demonstrates the danger of treating especially clay soils in the vadose zone as a low-conductive substrate, as the development of soil structure can dominate over the matrix property of the texture alone. This confirms that clay content and land cover strongly influence infiltration and reinforce PF, but seasonal dynamics and flow initiation also have an important impact on PF. [ABSTRACT FROM AUTHOR]

Prairie, or mima, mound topography often exists in once-abundant, native tallgrass prairie ecosystems throughout North America west of the Mississippi River. However, the abundance of undisturbed prairie mounds is decreasing in many areas due to urbanization and agricultural disturbance. The objective of this study was to evaluate the variations in soil physical, chemical, and estimated hydraulic properties among mound positions (mound summit, backslope, toeslope, inter-mound), soil depths (10-cm intervals from 0 to 90 cm), and soil moisture regimes (udic and aquic) in a native tallgrass prairie in the Ozark Highlands region of northwest Arkansas. Soil samples were collected in mid-April 2017. Soil clay concentrations increased with depth (P < 0.01) at each site position in both soil moisture regimes. The clay concentrations in the mound summits roughly doubled from 0 to 90 cm, while the clay concentrations in the backslope, toeslope, and inter-mound increased by three to six times from 0 to 90 cm. Soil organic matter contents decreased (P < 0.01) with depth at all site positions within both soil moisture regimes and were generally at least numerically largest at respective depth intervals at the inter-mound within the udic soil and at the mound summit within the aquic soil. Estimated saturated hydraulic conductivity decreased (P < 0.05) with depth at each site position and was largest in the inter-mound from 0 to 10 cm (63.4 mm h−1) and numerically smallest at the inter-mound from 70 to 80 cm (4.6 mm h−1). Results clearly indicated that prairie restoration and management practices should consider mounded and inter-mound landscape positions separately to best restore and/or preserve the ecological functioning of the unique mound features in the sparsely remaining tallgrass prairies. • Soil organic matter contents were generally greatest at the inter-mound in the udic soil. • Extractable soil sodium content was greater in the aquic soil from 50 to 90 cm. • Soil texture was silt loam from 0 to 90 cm at the mound summit and backslope. • Total nitrogen content was unaffected by mound position and soil moisture regime. • Soil property results reflect the complexity of tallgrass prairie ecosystems. [ABSTRACT FROM AUTHOR]