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In order to compare the influence of different soil types and stratification on water infiltration capacity, two main types of soil in the desert steppe, sierozem (S) and aeolian sandy soil (A), were selected, and infiltration simulation tests were conducted on homogeneous soil and layered soil (layer thickness 5, 10, and 20 cm), respectively. The results show that during the whole experiment, there was a small difference between S5A95 (aeolian sandy soil 95 cm thick was covered with sierozem 5 cm thick) and S10A90 (aeolian sandy soil 90 cm thick was covered with sierozem 10 cm thick) in the wetting front process, infiltration rate and cumulative infiltration, but there was a significant difference between S5A95 and S20A80 (aeolian sandy soil 80 cm thick was covered with sierozem 20 cm thick). In the initial infiltration stage, there was no significant difference between A5S95 (sierozem 95 cm thick was covered with aeolian sandy soil 5 cm thick) and A10S90 (sierozem 90 cm thick was covered with aeolian sandy soil 10 cm thick). However, with the increase of infiltration time, the wetting front process, A5S95, A10S90 and A20S80 had significant differences in terms of wetting front process, infiltration rate and cumulative infiltration. The infiltration capacity of A was significantly higher than that of S. Combined with linear Ä2 value and model parameters, the three infiltration models were comprehensively compared, and the fitting process and results of the general empirical model for the infiltration process of homogeneous soil and layered soil showed good results. Three models were used to simulate the water infiltration process of layered soil with different textures, and the order of the effect is as follows; general empirical model > Kostiakov model > Philip model. Soil type and layer thickness had a great influence on water infiltration process. When sierozem was covered with aeolian sandy soil 20 cm thick, the infiltration capacity was the best. As aeolian sandy soil was covered with sierozem 10 cm thick, the infiltration effect was the worst. Therefore, once coarse graying occurs on the surface of sierozem (the thickness of sand is more than 20 cm) or when the content of fine particles overlying aeolian sandy soil (the thickness of silt and clay soil is more than 10 cm) during ecological restoration is high, the soil hydrological characteristics will change significantly, which may lead to changes in vegetation types and even ecosystem structure. [ABSTRACT FROM AUTHOR]

Intensified drought exacerbated by climate change aggravates the development of soil desiccation cracking, triggering several weakening mechanisms in surface soils and eventually causing various geohazards and environmental problems. This study investigates the effect and mechanisms of a bio-mediated approach based on microbially induced calcite precipitation (MICP) for remediation of desiccation cracks in soils with different layer thicknesses. We conducted 5 MICP treatment cycles on clayey soil samples to explore the influence of layer thickness on the water evaporation properties, desiccation cracking behaviors, and calcium carbonate content and distribution of MICP-treated soils. The results show that the MICP treatment can significantly decrease the water evaporation rate, the surface crack ratio, average crack width, and total crack length of all soil samples. The crack reduction ratio reaches over 90% after 5 MICP treatment cycles. The soil layer thickness has an obvious influence on the effectiveness of MICP for the clayey soil treatment. Thicker soil samples exhibit wider desiccation cracks, which, in turn, require more MICP treatment cycles for remediation. The calcium carbonate content and distribution of MICP-treated soils is governed by the original desiccation cracks, the wider cracks in thicker soil samples result in the higher calcium carbonate content of soil nearby the cracks, and the denser cracks in thinner soil samples lead to the more homogenous distribution of calcium carbonate. The remediation of soil desiccation cracks is mainly attributed to the coupling effect of the soil volume change and the accumulation of calcium carbonate crystal during MICP treatment. The findings of this study provide new insights into the mechanisms of the interaction between MICP-treated soil and drought climate and contribute to developing environmentally friendly approaches for soil improvement in regions subjected to droughts. [ABSTRACT FROM AUTHOR]

This paper presents the results of field tests performed to investigate the installation effects of pre-bored grouted planted (PGP) pile in deep clayey soil. The variation of horizontal soil displacements, excess pore water pressures and lateral soil pressures was measured in the PGP pile installation process. The test results show that the drilling and grouting process induced large horizontal soil displacements in the soil within a radial distance of 2 d (d is pile diameter), and the maximum horizontal soil displacements induced by the drilling and grouting process were smaller than 15.9 mm when the radial distance reached 4–5 d. Moreover, the horizontal soil displacements decreased along the soil layer depth, as the superficial soil layers were of small deformation modulus and lateral soil pressure. The drilling process brought large excess pore water pressures in the soil when the radial distance was less than 3 d, and the excess pore water pressures induced by the drilling stage were all less than 55 kPa when the radial distance reached 4–6 d. The drilling process also induced some lateral soil pressure increases in the soil within a radial distance of 3 d, while the measured maximum lateral soil pressure increases were smaller than 10.9 kPa when the radial distance increased to 4 d. On the whole, the excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile were much smaller than that induced by the installation of driven PHC pile. Moreover, the horizontal soil displacements, excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile all recovered rapidly after the installation of pile, as the cemented soil in the pile hole was in liquid state after the drilling and grouting stage. [ABSTRACT FROM AUTHOR]

This paper analyzes the bearing capacity of two-layered soil medium using finite element (FE) software ABAQUS/CAE 2023. Although geotechnical engineers design foundations for layered soil, majorly current geotechnical studies emphasize single homogenous soil. So, this research has significant novelty as it focuses on layered soil and adds to the current literature. A nonlinear FE model was prepared and analyzed to determine the ultimate bearing capacity of two-layered soil (sandy soil over clayey soil). The Drucker–Prager and Mohr–Coulomb models were used to represent sandy soil and clayey soil layers, respectively. Strip footing material properties were considered isotropic and linearly elastic. This study performed parametric studies to understand the effects of thickness, unit weight, and the modulus of the elasticity of sandy soil on the ultimate soil bearing capacity. Additionally, it also analyzed the effect of the cohesive strength of clayey soil on layered soil bearing capacity. Results showed that an increase in sandy soil layer thickness strengthens the layered soil, and thus, improves the bearing capacity of soil. Increasing the sandy soil layer thickness over footing width (h1/B) ratio from 0.15 to 2.0 improved the ultimate bearing capacities with elastic settlements of 350 mm and 250 mm by 145.62% and 101.66%, respectively. Additionally, for a thicker sandy soil layer, an increase in the unit weight and modulus of the elasticity of sandy soil led to higher ultimate bearing capacity. Furthermore, it was concluded that an increase in clayey soil's cohesive strength from 20 kPa to 30 kPa resulted in a 24.31% and 3.47% increase in soil bearing capacity for h1/B = 0.15 and h1/B = 2.0, respectively. So, the effect of cohesion is prevalent in the case of a thicker clayey soil layer. [ABSTRACT FROM AUTHOR]

The theoretical and practical studies of the cyclic loads resulting from the movement and passage of trains on the unsaturated subgrade to determine the effect of the degree of saturation and moisture content on the foundations and infrastructure of the railway lines, especially the settlement in the railway lines as a result of the development of the train loads. Thirty-six laboratory experiments were carried out using models that simulate a railway with nearly half the scale of the real one, using an iron box of (1.5 × 1.0 × 1.0) meters and a layer of clay soil with a thickness of 0.5 m representing the base layer, were constructed inside it. Above it, there is a layer of crushed stone representing a 0.2 m thick ballast, topped by a rail line of 0.8 m long installed on three sleeper beams with dimensions of 0.9 m (0.1 × 0.1 m). The subgrade layer has been constructed at different saturation degrees as follows: 100, 80, 70, and 60%. The tests were carried out using different load amplitudes and frequencies. These experiments investigated the effect of the subgrade degree of saturation on the value of the stresses generated on the surface and the middle (vertical and lateral stresses) and the settlement of the subgrade. In the case of unsaturated subgrade soil, an increase in load frequency has a clear effect on increasing the generated stresses in the subgrade layer, especially with lower saturation levels. However, the results and measurements of these experiments found that the load frequency almost had no effect on the values of the stresses generated on the surface and inside the subgrade layer with a 100% degree of saturation. The results of the investigation demonstrated that, while load frequency had a minimal effect on track-panel settlement, it increased with the load amplitude and subgrade soil saturation degree. The change of settlement of the track panel with the number of cycles has a high rate at the beginning; after a while from that, it decreases gradually until, after some value of the number of cycles, the settlement changes at a very low rate and gradually. [ABSTRACT FROM AUTHOR]

The research work was conducted in order to get an insight about the soil physicochemical properties in central and southern dry zones of coconut growing areas of Hassan district, Karnataka during 2022-23. The soil samples from surface (0-30 cm) and sub-surface (30-60 cm) were collected under central and southern dry zones of Hassan district for the study. Soil samples collected from different agro-climatic zones were analyzed for both physical and chemical properties. The present investigation revealed that soil texture was sandy clay loam to sandy loam in surface soil and sandy clay in sub-surface depths. The soil pH was neutral to mildly acidic in soils of both the agro-climatic zones and the mean electrical conductivity value were normal. The organic carbon content in surface and sub-surface depths ranged from low to high in coconut growing soils of both the agro-climatic zones. Soil pH and electrical conductivity increased with increase in soil depth whereas, the organic carbon content decreased with depth. The average available nitrogen, phosphorus and sulphur status in surface soils of coconut gardens of study area were observed to bemedium and decreased with depth. Whereas the available potassium status was recorded to be higher and decreased with depth. Among the micronutrients, the mean available iron, manganese and copper content were observed to be sufficient where as, insufficient zinc content was noticed in the study area. The study enlightend the varied nature and properties of the coconut growing soils of central and southern dry zones of Hassan district and represented fertility status of the soils to enhance coconut palm health and productivity. [ABSTRACT FROM AUTHOR]

Climate change and irresponsible urbanization practices are anticipated to further exacerbate flood risk. The different soil types' physical, chemical, and biological characteristics significantly impact surface water movement, porosity, permeability, and infiltration potential. Therefore, soil infiltration is perhaps the most challenging and crucial process to characterize on a field scale. Various methods have been developed to measure the infiltration rate empirically and theoretically. However, the relationship between different soil types and infiltration rates in Sarawak remains unknown as no previous study has been conducted. This study uses the Storm Water Management Model (SWMM) to evaluate the infiltration rates for five different soil types: clay, clay loam, loam, sandy loam, and sand. 30 samples of various types and soil depths were examined at intervals of 0.5 m, 1.0 m, 1.5 m, 2.0 m, 2.5 m, and 3 m. The study was carried out using a standardized slope of 0.7% and an impervious land of 25% with a catchment size of 2 acres. Extreme rainfall data on the 5th and 6th of December 2021 was input into the infiltration model. Results showed that the difference between initial and final water storage of all the investigated soil depths for clay, clay loam, loam, sandy loam, and sand was found to be 48.42 mm, 51.20 mm, 58.01 mm, 66.96 mm, and 115.54 mm, respectively. The findings demonstrated that clay has the lowest water storage capability, followed by clay loam, loam, and sandy loam. Sand could store a comparatively large amount of rainwater. In contrast, sand has the highest infiltration rate with 2.541 mm/h, followed by sandy loam with 1.835 mm/h, loam with 1.432 mm/h, clay loam with 1.039 mm/h. Clay has the lowest infiltration rate, with 0.852 mm/h. This research concluded that sandy soil could significantly reduce surface runoff and help reduce flood risk in urban regions. [ABSTRACT FROM AUTHOR]

To achieve the carbonization utilization of Triarrhena lutarioriparia straw and relieve the environmental pressure caused by improper disposal in the Dongting Lake area, the agricultural efficiency of biochar derived from Triarrhena lutarioriparia was clarified. Two typical paddy soils in southern China, namely reddish clayey soil developed from a Quaternary laterite parent material and granitic sandy soil developed from a granite parent material, were selected. Six treatments with different dosage of biochar (0, 1%, 2%, 4%, 6%, and 8% of the soil mass，0-20 cm soil depth) were set. Rice pot experiments were conducted in 2020 to study the effects of different application rates of Triarrhena lutarioriparia biochar on rice nutrient utilization characteristics in two typical soils. The results showed different application rates of Triarrhena lutarioriparia biochar and soil types had certain effects on dry matter accumulation and nutrient uptake by rice organs and aboveground structures. With the addition of biochar, compared with the treatment without biochar, the accumulation of dry matter of rice increased from 0.6% to 18.6% and from 15.5% to 42.4% in the granitic sandy soil and reddish clayey soil, respectively. With the addition of 4% biochar, the accumulation of nitrogen, phosphorus, and potassium nutrients in the rice plant of the treatment increased by 8.6%, 10.5%, and 82.5% in the granitic sandy soil and by 33.8%, 100.0%, and 125.3% in the reddish clayey soil, respectively. The quadratic regression equation and fertilizer – carbon coupling model fitting showed that the optimal addition amounts of biochar in the granitic sandy soil and reddish clayey soil were 2.51% and 4.80% for nitrogen utilization, 4.33% and 7.03% for phosphorus utilization, and 4.67% and 4.81% for potassium utilization, respectively. Therefore, the application of Triarrhena lutarioriparia biochar is conducive to promoting the accumulation and growth of nitrogen, phosphorus and potassium nutrients in rice, and the amount of biochar added and soil conditions are important factors affecting the coupling effect of fertilizer and carbon. [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]

Microbially induced calcium carbonate precipitation (MICP) is one widespread approach to soil clay improvement in sustainable biological engineering in the world. The green and efficient approach can also greatly contribute to a series of environmental and ecological challenges. Among them, urea-producing bacteria can be used to induce calcium carbonate precipitation for better soil consolidation. Bacterially generated urease enzymes can decompose the urea to further promote the binding of Ca2+ and CO32-. Therefore, the calcium carbonate precipitation can be expected to apply to desertification combating. However, the urea-producing bacteria can be limited to environmental adaptability and weak function in a harsh desert environment. Many technical bottlenecks are urgent issues for the sand-fixation using calcium carbonate precipitation induced by urea-producing bacteria. It is a high demand to develop native urea-producing bacteria. In the preliminary research, the strain of Sporosarcina pasteurii was identified from the aeolian soils in the Mu Us desert. In this research, the optimal reaction conditions were determined to verify the sand-fixation effect in the desert soil after optimization. A series of single-factor experiments were designed during 0-72 h with the different experimental gradients by pH (7, 8, 9, and 10), bacterial inoculum (1%, 2%, 3%, 4%, and 5%), the ratio of bacterial and cementing solution (25%, 50%, and 75%), and temperature (30, 35, and 40 ℃). The initial urease activity and calcium deposition rate were tested using the response surface method. The optimal reaction factors and conditions were then determined from the six factors (reaction time, pH, bacterial inoculum, the ratio of bacterial and cementing solution, reaction temperature, and initial urease activity). The sand-fixation experiments were carried out on the aeolian soil from the Mu Us desert under optimized conditions. Mineral morphologies and properties were then characterized by the scanning electron microscope (SEM). The thickness and hardness of the soil consolidated layer, soil particle distribution, soil organic matter and calcium carbonate content were measured to calculate the erodibility factor (EF) under soil wind erosion. The results showed that: 1) The main reaction drivers of calcium carbonate precipitation were determined as the reaction temperature, reaction time, pH value, as well as the ratio of bacterial and cementing solution. An optimal combination of conditions was achieved at 34.47 ℃, 71.68 h, pH 7.73, and 74.94% ratio. In this condition, the maximum rate of calcium deposition was 42.33%. 2) The calcium carbonate precipitation was obtained in the polycrystalline phase composition with the cubic, rhombic, spherical, and amorphous under the optimized conditions. Diverse calcium carbonate precipitation was formed on the surface of sand grains, or embedded in the sand grains. 3) Sand-fixation by induced calcium carbonate precipitation was significantly enhanced after optimization. The number of sand particles increased significantly (P<0.05), and the thickness and hardness of the soil consolidated layer increased by 5 and 10 times, respectively. The contents of organic matter and calcium carbonate increased significantly, whereas, the wind EF decreased from 0.94 to 0.66. Therefore, the urea-producing bacteria-induced calcium carbonate precipitation can serve as the new effective and favorable sand fixation for desertification combating in the future. It is still necessary to develop the distribution of simultaneous ecological restoration, in order to gradually promote this new technology in large-scale field experiments. Consequently, in the field application, the sand fixation effect can be enhanced to further determine the application time and water under suitable conditions and the soil compaction will be avoided by appropriately breaking. [ABSTRACT FROM AUTHOR]

Based on the soil temperature and humidity data of soybean farmland under conservation tillage in Northeast China in the published article, the impact of conservation tillage measures on the soil hydrothermal status of soybean farmland in Northeast China was quantitatively assessed by using conventional tillage (CT) as a control, no-tillage (NT), reduced tillage (RT), straw mulching (SM), and no-till straw mulching (NTSM) as treatments. The results showed: compared with CT, conservation tillage increased the soil volume water content of 0-170cm soil layer in soybean farmland in Northeast China by 9.2%, and reduced the temperature of the shallow soil layer (0-30cm) by 8.2%. Four conservation tillage could increase soil moisture under different climatic conditions; straw mulching could increase soil moisture content throughout the growth period of soybeans, and the effect on soil hydrothermal was greatest during the nutrition period of soybean, and soil temperature increased with the increase of straw mulching; the magnitude of soil temperature reduction by conservation tillage decreases with the decrease of soil clay particles, the magnitude of soil moisture increased by conservation tillage decreases with the increase of soil depth. Among them, NTSM at different soil depths was the most obvious effect of water storage and moisture retention, and the soil moisture in the soil layer of 0-20cm was increased by 32.9%. In summary, conservation tillage could increase soil moisture but reduce soil temperatures. Temperature, precipitation, growth period, straw mulching amount, soil type and soil depth all had an impact on soil hydro-thermality in soybean farmland under conservation tillage. [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]

• The failure model of stiff-over-soft clay varying with soil parameter. • A new calculation method for ultimate bearing capacity of spudcan. A jack-up platform is prone to a 'punch-through' accident when working on the stiff-over-soft clay foundation. To assess the risk of punch-through, it is necessary to plot the bearing capacity-penetration curve for evaluating the penetration depth of the pile leg or to calculate the ultimate bearing capacity of the spudcan and compare it with the preload. However, accurate prediction of spudcan bearing capacity is not easy. In this paper, the failure mode about the stiff-over-soft clay under different geological conditions when punch-through occurs is discussed using coupled Eulerian lagrangian (CEL) method, varying the strength ratio between soft and stiff soil layers, the thickness of stiff soil relative to the spudcan diameter, and the non-homogeneity factor of soil strength. Based on the soil failure model with varying soil parameters, a new calculation method for ultimate bearing capacity of spudcan is proposed and then verified against existing centrifuge test results. The results show that the shape of soil shear plane in stiff clay is significantly affected by the strength ratio of soil layer and the non-homogeneity factor of soil strength. And the presented new method whose prediction errors compared with centrifuge test results are less than 5%, has better calculation accuracy than the ISO (International Organization for Standardization) method, which is valuable in guiding the calculation of the ultimate bearing capacity of the spudcan and ensuring the safe operation of the jack-up drilling units on stiff-over-soft clay. [ABSTRACT FROM AUTHOR]

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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]

The object of research is the processes of interaction of the cutters of the working body of the chain trench excavator on the basis of the semi-blocked critical depth mode of soil cutting. One of the most problematic places is that the known analytical and experimental models of interaction of multi-scraper chain trench excavators with soil do not determine the parameters and modes of their operation based on critical depth cutting of soils. Therefore, the design of work equipment for given conditions on the basis of such dependencies does not provide the minimum energy consumption and maximum productivity of the work process. The research used the method of analytical calculation of parameters of installation of soil-developing elements and determination of energy performance of multi-scraper chain working body of trench excavator on the basis of semi-blocked critical-depth soil cutting regime. The proposed calculation method allows to determine the parameters of installation of the working body and placement of soil development elements and to quantify the energy performance of multi-scraper chain working body of the trench excavator based on semi-blocked critical depth of soil cutting mode. The obtained method of calculation, in contrast to existing empirical estimates, allows developing options for improving the parameters of multi-scraper chain working body. As a substantiation of this conclusion the conceptual variant of technical realization of the working equipment is offered, namely, allows to prove expediency of the choice of the semi-blocked scheme of arrangement of cutters of critical deep cutting of soil of a working body of a trench multi-scraper excavator. The conducted energy analysis showed that it is more expedient to use a multi-scraper chain working body of a trench excavator on the basis of a semi-blocked critical-depth regime of soil cutting. For example, for soil semi-solid clay with blocked cutting, cutting angle αc = 20–30°, cutter width b = 0.02 m the energy intensity of the working process varies within E = 191–233 kJ/m³; for semi-blocked cutting under the same conditions – E = 187–191 kJ/m³, which is 2–18 % less. [ABSTRACT FROM AUTHOR]

The present study deals with the assessment of surcharge induced consolidation effect on the shear strength of clayey soil and the pile capacity. The study was performed at a construction site located near the coastal area of Tamil Nadu, India. A series of laboratory tests were performed on the disturbed and undisturbed soil samples collected from the site after doing few in-situ tests. The pile capacity was estimated as per the Indian Standards using the properties of soil assessed from the geotechnical investigation and compared with that of field load test on pile. The bored piles were cast upto a depth of 16 m which pass through clayey soil with soft to hard consistency and rest on very dense sandy soil layer. Due to very low subgrade reaction modulus of top soil layer, the lateral capacity of 450 mm diameter pile tested was lesser than the designed. Hence, the design was revised with the 600 mm diameter pile. From the detailed load test program on the 600 mm diameter piles during fixed interval of time, it was found that the site development by 2 to 3 m earth filling induced the consolidation and improved the shear strength of the soil upto a depth of 5 m. The vertical and lateral load capacity of pile was also improved to a maximum of 15% and 70%, respectively after 2 years. The results of the investigation proved the importance of time-dependent behaviour study on the pile capacity assessment. [ABSTRACT FROM AUTHOR]

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.)

The jack-up platform is prone to punch-through accidents during the installation and preloading. How to effectively predict the bearing capacity of spudcan is a major concern in the industry. This paper reports a new method for predicting spudcan penetration curves on stiff-over-soft clay based on numerical results. A three-dimensional nonlinear numerical model of "spudcan-seabed" is established using the CEL method of ABAQUS software with the remolding softening characteristic of saturated clay considered. A comprehensive parametric study is carried out to analyze the soil deformation beneath the spudcan and the spudcan bearing characteristics at both peak and post-peak of the penetration curve, varying the strength ratio between soft and stiff soil layers, the thickness of the stiff soil relative to the spudcan diameter, and the non-homogeneity of soft soil strength. Based on these numerical solutions, the formulas for calculating the bearing capacity and penetration depth of spudcan are established, and then the detailed procedure is given for constructing the penetration curve, at which the peak bearing capacity accounts for the vertical movement of soil under the spudcan. Finally, the comparison of the calculation results with centrifuge tests demonstrates the effectiveness of the new method in predicting the spudcan bearing capacity-penetration curve. • A new calculation method for bearing capacity of spudcan. • The movement variation of soil beneath a spudcan at both peak and post-peak of penetration curve. • Evaluation method of soil plug height. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the extent and causes of soil compaction of the apple orchards in the Weibei Dry Highland. Nine 'Red Fuji' apple orchards with number of planting years in the ranges of <10‐year, 10–20‐year and >20‐year were included. Soil bulk density, porosity, penetration resistance, organic matter (SOM), clay, water and soil aggregate size distribution were determined. The results showed that the subsoil (20–30 cm) of apple orchards was compacted. The bulk density and packing density (PD) of subsoil increased sharply by an average of 17.9% and 18.0%, respectively, relative to topsoil (0–10 cm), and the porosity decreased by 17.0%. The depths of the soil layer with penetration resistance exceeding 1,000 kPa became shallower with increased planting years. Compared with <10‐year apple orchards, the bulk density, PD and soil penetration resistance in 10–20‐year and >20‐year apple orchards were increased, respectively, by 5.3%, 5.3% and 29.3%, but the porosity decreased by an average of 8.2%. Compared with topsoil, the water‐stable aggregates of >0.25 mm and the mean weight diameter of wet sieve aggregates (MWDW) of compacted soil were 57.6% and 25.4% lower, respectively. Soil clay content increased with soil depth from 0 to 60 cm, but the SOM showed an opposite trend. Additionally, there was a dry soil layer at a depth of 20–40 cm. Thus, the factors affecting the soil compaction process were determined to be inferior agglomeration ability of soil, internal soil desiccation, and the downward migration of soil clay particles. [ABSTRACT FROM AUTHOR]

Civilian and military shooting range facilities cause environmental issues in several countries due to the accumulation of Potentially Toxic Elements; as a result of weathering of ammunitions accumulated into the soils. The contents and distribution of Cu, Ni, Pb and Zn were analyzed in 12 soils in an abandoned clay target shooting range at two different depths (0–15 and 15–30 cm). Single extractions (CaCl2 and DTPA) and Tessier sequential extraction were conducted to assess the PTE mobility and the PTE distribution in the different soil geochemical fractions at both depths. High total contents of Pb were found at both soil depths, while Cu, Ni and Zn showed lower significance levels. Copper, Ni and Zn are mainly associated with the residual fraction (> 95% of total content in all cases). However, Pb was highly associated with exchangeable fractions (21–52%), showing a high mobility at both depths. With moderate-high contents of organic matter (6–12%), the studied soils have acidic values and low levels of Al, Fe and Mn oxides that favors the migration of Pb through the soil profile and potential transformation to more mobile forms (Pb0 to Pb2+ and Pb4+). Although Pb reduced downward mobility in soils, due to the specific conditions of these facilities and the lead source (weathering of ammunition), risk assessment studies on clay-target shooting and firing range facilities should study the potential migration of Pb through the soil profile. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology 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.)

In the present study, the draft requirement of five tyne duck foot plough was studied on clay soil for different soil moisture content, depth of operation and forward speed of tractor using a specially designed three-point hitch dynamometer. The designed dynamometer was matched with the tractors having category II or III hitch systems. The data acquisition system adopted for the dynamometer had NI WSN-3214 Strain Nodes, NI 9792 WSN real-time Gateway and NI LAB View 2013 software. A data logger program was developed for the three-point hitch dynamometer. The investigation was carried out at that three levels soil moisture content (10-13%, 14-16% and 17-20%), at three different depth of operation (15, 20 and 25 cm) and three levels of the forward speed of tractor (3, 5 and 7 km h-1). The designed dynamometer performed well in all the levels of the experiment. The results showed that draft force required for five tyne duck foot plough was increased (408 kg) with an increase in soil moisture content (17-20%), whereas it was increased (408 kg) with an increase in depth of operation (25 cm) and forward speed of tractor (7 km h-1). The suitable sweep, the forward speed of operation, depth of operation and soil moisture content that influenced the draft force and energy consumption for tillage operation of duck foot type plough were identified and developed duck foot plough was better coverage with better soil operation. [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]

Cable stayed bridge has the highest popularity because of its aesthetic look & architectural marvelous. Although the analysis and construction, complicities are at its top because of its higher flexibility. In that case, the response of the bridge as a whole i.e the structure, the foundation, and the soil underlying and surrounding the foundation become more predominant because of load transfer mechanism and overall bridge behavior. The post-failure analysis deduces that soil-structure interaction (SSI) is a very pivotal phenomenon influencing the dynamic response of massive structures. Soil-structure interaction (SSI) analysis evaluates the collective response of the above three linked systems. Here, an attempt is made to understand the SSI effect for H shape pylon Cable stayed Bridge; for that FEM model is prepared with different foundation depth and different soil conditions. The effect of SSI is sitespecific, it cannot be generalized. The depth of the foundation plays a vital role in bridge response. SSI effect increases time period of the structure by about 5-8 %. Bridge founded on stiff and soft clayey soil proves a more rigid connection as compared to sandy soil. [ABSTRACT FROM AUTHOR]

In order to clarify the effect of mixed planting in the dynamics of phosporus (P), we assessed the fractions of this element in mixed plantings of Eucalyptus urophylla × E. grandis (Urograndis) and Acacia mangium in a tropical soil clay, analysing changes in the fractions of P and examining the correlation of these changes with the fractions of soil organic matter. Pure stands of Urograndis (E) and A. mangium (A) (0A:100E and 100A:0E) and mixed stands of the two species (50A:50E and 37A:66E) were established. The fractionation of P, the granulometric fractionation of organic matter and the labile carbon (POXC) were determined at soil depths of 0–5 and 5–10 cm. Regarding the availability of P, organic parts contributed 34.6% to 38.1% relative to the total P, with the highest percentages being observed for the moderately labile fraction. Highest levels of labile organic P were observed in the mixed plantations. About soil carbon (C), the highest levels of the more labile C fractions were recorded in plantations in which Acacia was present. Mixed plantations were found to show a greater balance between labile P and C fractions. The C fractions warrant particular attention in future studies, notably those related to the emission of greenhouse gases. [ABSTRACT FROM AUTHOR]

Short‐term (5 years) impact of tillage and residue management practices on physical properties and organic carbon (OC) of a silty clay soil was evaluated in a rice–wheat rotation in the Indo‐Gangetic Plains of Bihar. The experiment had three conservation agriculture (CA) practices: one full (direct‐seeded rice (DSR)–no‐tilled wheat (NTW)–no‐tilled mung bean (NTMB); fCA) and two partial (puddled transplanted rice (PTR)–NTW–conventionally tilled mung bean (CTMB); pCA1 and unpuddled transplanted rice (UPTPR)–conventionally tilled potato+maize (CTP + M)–NTMB; pCA2), which were evaluated against full conventional practice (puddled transplanted rice (PTR)–conventionally tilled wheat (CTW); TA). Subsurface compaction reduced and soil aggregation improved under both full and partial CA. Macro‐ and water‐stable aggregates increased to a large extent (26 and 11%, respectively) in full CA and to a lesser extent in partial CA, mostly due to increase in coarse macroaggregate (2–8 mm) contents in the 0–10 and 10–20‐cm depth soil layers. Steady‐state infiltration rate nearly doubled under full CA, with larger pore volume recorded in 10–20 and 20–30‐cm depth soil layers. The CA increased OC associated with all size fractions of aggregates in the surface soil layer (0–10 cm), but a higher amount of C was associated with macroaggregates, indicating relative stabilization of OC in the soil under CA. Change in bulk soil OC was larger in the 0–10‐cm depth soil layer in favour of CA, which also had an 11% increase in OC stock in the 0–30‐cm depth soil layer. Improvement in soil physical condition did not effectively translate into increased rice or wheat yields, but the system productivity increased largely. Highlights: Conservation agriculture (CA) resulted in 11–12% higher macro‐aggregation compared to conventional practice (CT).Macro‐ and total pores reduced in the 0–10 cm depth soil layer but increased in the 10–20 cm depth soil layer under CA.CA resulted in 27–35% higher aggregate‐associated OC content and 11% increase in OC stock at 0–30 cm.Full/partial CA improved soil physical condition and the productivity of rice–wheat systems in the Indo‐Gangetic Plains. [ABSTRACT FROM AUTHOR]

In savannas, partitioning of below‐ground resources by depth could facilitate tree–grass coexistence and shape vegetation responses to changing rainfall patterns. However, most studies assessing tree versus grass root‐niche partitioning have focused on one or two sites, limiting generalization about how rainfall and soil conditions influence the degree of rooting overlap across environmental gradients.We used two complementary stable isotope techniques to quantify variation (a) in water uptake depths and (b) in fine‐root biomass distributions among dominant trees and grasses at eight semi‐arid savanna sites in Kruger National Park, South Africa. Sites were located on contrasting soil textures (clayey basaltic soils vs. sandy granitic soils) and paired along a gradient of mean annual rainfall.Soil texture predicted variation in mean water uptake depths and fine‐root allocation. While grasses maintained roots close to the surface and consistently used shallow water, trees on sandy soils distributed roots more evenly across soil depths and used deeper soil water, resulting in greater divergence between tree and grass rooting on sandy soils. Mean annual rainfall predicted some variation among sites in tree water uptake depth, but had a weaker influence on fine‐root allocation.Synthesis. Savanna trees overlapped more with shallow‐rooted grasses on clayey soils and were more distinct in their use of deeper soil layers on sandy soils, consistent with expected differences in infiltration and percolation. These differences, which could allow trees to escape grass competition more effectively on sandy soils, may explain observed differences in tree densities and rates of woody encroachment with soil texture. Differences in the degree of root‐niche separation could also drive heterogeneous responses of savanna vegetation to predicted shifts in the frequency and intensity of rainfall. [ABSTRACT FROM AUTHOR]

This article presents the performance of the short-term bearing capacity on soft clay soil treated by Kenaf geotextile under vertical loading via a small-scale modelling test at unit gravity. The ground model was formulated by consolidating kaolin in a rigid testing compartment. In the loading test, the strip footing was represented by a rigid footing. For the treated case, a series of tests were performed to examine the effects of the burial depth of the Kenaf geotextile on the bearing capacity of the soft soil. The Kenaf geotextile was laid beneath the rigid footing (at the ground surface) and at 50, 75 and 100 mm depth from the soil surface. All the measured results of the Kenaf geotextile treated ground were compared with the untreated ground. The incorporation of Kenaf fibre geotextile was observed to enhance the bearing capacity of soft cohesive clay up to 281% depending upon the depth of the installed geotextile. The geotextile at the surface provided the highest bearing capacity and sustained the highest displacement at failure. The outcome of this research will promote the use of natural fibre geotextiles as sustainable earth reinforcement in temporary earthwork applications. [ABSTRACT FROM AUTHOR]

Soil cracks are an important physical property of expanded clay soils accompanied by distinctive morphological features such as Galgi and Silkensides as a result of the expansion and contraction processes by moistening and drying the soil which effect on water movement and its flow into the soil body, Three experiments were conducted to study the pattern of soil cracks formation and to show the extent of the effect of adding sand and sheep residues on the cracks forms. Some morphological characteristics resulted from the cracking process such as Number of separate pieces, Cracks length, Cracks width, Thickness of hard part, Area of cracked pieces and Crack pattern were calculated in this study. The morphological description of the cracks showed a clear difference in their forms and the width of the cracks in proportion to the depth of the cracks with their width. The results showed a decrease in the width and length of the cracks with an increase in the addition of sand and sheep residues. Significant differences appeared in values of Crack Intensity Factor (CIF) when adding sheep residues by 6% compared with 6% sand and control treatment. The value of CIF was (2.25%, 2.60% and 3.78%) for sheep residues, sand and control respectively, thus it affected the behavior and pattern of soil cracks. [ABSTRACT FROM AUTHOR]

Purpose: Land subsidence has caused serious geological damage in many countries, including China. Soil pore number, size, shape, and pore size distribution affect soil deformation and thus land subsidence. Quantification of complex pore structures in different soil types and at various soil depths, however, remains cumbersome. The objective of this study was to quantify pore characteristics of three different soil types using computed tomography (CT) technique, investigate the effects of soil depth, examine the relationships between various parameters, and preliminarily determine the pore deformation pattern. Materials and methods: Undisturbed soil samples (70 mm diameter × 50 mm height) of clay, silt, and silty clay soils were collected from two 300-m-deep engineering geological boreholes on both sides of the Xi'an D7 ground fissure. One hundred CT images were acquired for each soil sample. Soil pore characteristics and morphological parameters, including porosity, macroporosity, coarse mesoporosity, microporosity, number of pores, number of macropores (diameter > 1000 μm), number of coarse mesopores (diameter 200–1000 μm), number of micropores (diameter < 200 μm), circularity, structure model index, degree of anisotropy, and the Euler number, were analyzed. Results and discussion: Micropores were generally regularly shaped and the main contributors to the total number of pores, whereas macropores were mostly elongated and contributed to total porosity. With increasing depth, the most noticeable changes appeared in silt soil and the least noticeable in clay soil. The alternate pore deformation pattern was significant in silt and silty clay soils. Conclusions: Soil depth significantly influenced all soil pore parameters, whereas soil type significantly affected the remaining parameters, except circularity and degree of anisotropy. The elongated macropores in silt and silty clay soils favor land subsidence in the Xi'an area. The present results can help optimize the groundwater exploitation layer, reducing soil compaction and land subsidence in this area. [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]

Siagona europaea and Poecilus pantanellii are two carabid beetles strictly bound to clay soils typical of the Italian Apennines. The first exhibits a very flat body whereas the other has more "normal" proportions, suggesting a very different use of space. We tested the use of space of both species using three sets of live pitfall traps put in place at different depths in the clay soil of a Mediterranean Hedysarum pasture. Poecilus pantanellii is a very early spring breeder and more than 90% of its individuals show epigean locomotory activity. Siagona europaea's activity begins later, when the clay fissures become larger and deeper, and in the months of June and July about 80% of its population lives in the subterranean soil crevices. Morphometric measurements support these space use strategies: P. pantanellii has a wider antenna/eye angle and shorter antennae, indicating a possible visual component in prey recognition, as well as a thicker body and robust trochanters linked to "wedge pushing"; whereas S. europaea has longer antennae and a smaller antenna/eye angle suitable for olfactory-tactile prey recognition, and also has an extremely flat body and small trochanters. In the summer individuals climb up and down in the crevice system of clays searching for their specialised prey (worker ants exploring the space around their ant nests). [ABSTRACT FROM AUTHOR]

The Ruczaj district in Kraków is the potential building area of high flat blocks for inhabitants. This area is built of the gypsum basement covered by the soil and impermeable clay beds with several meters of thickness. The flat blocks must be set on the textured gypsum layer. In the result of the rainfall and static pressure of the blocks, the water with SO42− increases up to the groundwater level, become the great threat for the flat blocks. The water creates specific hydrogeological conditions occurring in the zone of the building's foundations. To eliminate the mentioned threat, we should determine precisely the thickness of the soil and impermeable clay as well as the depth of the gypsum basement. Based on the electromagnetic parameters of the geological formations, the Ground Conductivity Meter and DC resistivity methods were used to solve the mentioned problems. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Protection & Pathology 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.)

Many factors including climate, type of rootstock, soil properties, geological factors, plant nutrition and irrigation affect the quantity and quality of orange fruit. In this study, the relations between citrus orchards conditions, their soil properties and leaf elements concentration and fruit quality were evaluated. The experiment was conducted as a randomized complete block design and soil, fruit and leaf samples were collected from six different regions of Darab, Fars, Iran. After fruit sampling, land properties such as physiographic features, slope, gravel, altitude and soil physical and chemical properties such as percent of sand, silt, clay, organic matter, calcium carbonate, pH and electrical conductivity and also N, P, K, Fe and Zn availability were determined. Several morphological and qualitative characteristics of fruit including, rind and flesh weight, rind thickness, length, diameter, fruit granulation, flavor, sugar and fruit juice acidity were determined. The contents of N, P, K, Fe and Zn in the collected leaves were determined. Three random samples were taken for each orchard and each replicate consisted of one tree. Results showed that fruit weight was correlated with the land slope, soil pH, electrical conductivity, soil organic matter content, soil N, P and K and leaf K content. Rind thickness showed a significant positive correlation with parameters such as land slope, electrical conductivity, organic matter, silt, clay and soil N, P and Zn and leaf N and K content. However, there was a significant negative correlation between rind thickness and soil gravel and sand contents. The relations between fruit granulation and soils calcium carbonate, gravel, organic matter content and soil K concentration were significant. TSS to TA ratio in fruit juices had significant negative correlation with land altitude, soils silt, calcium carbonate contents and leaf K content. Generally, many soil properties had significant effects on fruit quality but it seems that soil texture, organic matter, pH, P and K were more effective on fruit quality. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation of torpedo anchors penetrating into sand-overlying-nonhomogeneous clay deposit, with the main objective of predicting the anchor embeddment depth after it penetrates through the top sand layer. The behavior of the torpedo anchor and soil failure mechanisms during the installation process are analyzed using large deformation finite element (LDFE) methods. To validate the numerical models, comparisons are made with data from existing centrifuge and field tests. An extensive parametric study is then conducted, exploring a wide range of soil properties, soil layer thickness, anchor velocities, and parameters related to torpedo anchor geometry. Two intriguing findings emerge from the analysis. Firstly, there is an evolving soil failure, with the strain-softening region expanding in the clay near the boundary between the two soil layers. Secondly, the velocity profile during both the acceleration and deceleration stages varies with different sand layer thicknesses, displaying a nonlinear relationship with the anchor's final embedment depth. Based on the findings, a simple design procedure is developed to account for the influencing factors on the anchor installation depth. This procedure is expected to be valuable for engineers seeking to estimate the behavior of torpedo anchor installations in sand-overlying-nonhomogeneous clay soil deposits. • The installation of torpedo anchors in sand-overlying-nonhomogeneous clay is explored through the CEL analyses. • The installation depth, velocity profiles and failure patterns of the anchor are studied through parametric analyses. • A design procedure is proposed for predicting the anchor penetration depth in sand-overlying-nonhomogeneous clay deposit. [ABSTRACT FROM AUTHOR]

The species of the genus Urochloa has been highlighted in the crop-livestock integration and practices such as the type of seed used, and the depth of sowing are fundamental for the establishment and production of the pasture. The objective of this research was to evaluate the emergence and growth of plants of Urochloa brizantha cv. Marandu, originating from seeds incrusted or not, sown in different depths and soils. The experimental design was a randomized block design with four replications. The treatments were arranged in a 2x5 factorial scheme, composed of two types of seeds (incrusted or not) seeded in five depths (0; 1; 2.5; 5; 10cm) in medium textured and clayey soils. Plants of U. brizantha from seeds incrusted and cultivated in medium textured soil presented higher emergence, but lower growth in relation to the plants coming from non-incrusted seeds. In soils of clayey texture, the use of incrusted seeds promoted a greater speed of emergency, but less growth of the plants. The sowing of U. brizantha at 1.0 and 2.5 cm depth provided a higher emergence speed, regardless of soil texture and type of seed. After forage cutting, the greatest tillering of regrowth was observed in plants from non-encrusted seeds and sown in soil up to 2.5 cm deep. At regrowth, there was no effect of treatments on forage yield. [ABSTRACT FROM AUTHOR]

Rice-wheat rotation area, with heavy clay soil texture, that it is wheat planting area accounts for more than 37% of the total wheat sowing area in China as one of the major grain production bases, and rice-wheat rotation is the main cropping pattern in this region. Meanwhile, because of the shortage crop stubble and more rainfall in autumn, which lead to serious wet damage during the tilling and seeding stage for this field. Currently, most of the existing no-tillage and less-tillage seeding equipment for wheat sowing in rice stubble areas were optimized and developed on the basis of traditional contact-type wheat seeding technology, which lead to adhesion and serious blockage phenomenon, as well as increasing of operating resistance and power consumption during working. Therefore, a innovative technical proposal of non-contact type pneumatic seeding technology that could avoid contacting between sowing parts and soil was introduced in this paper, which in order to solve the problems of soil adhesion, blockage, drag increment as well as poor sowing quality for wheat seeders under the condition of sticky heavy loam clay in rice-wheat rotation areas. Experiment that utilized a self-made platform for wheat pneumatic seeding was conducted, which could rip wheat seed into the soil condition of clean seed bed without straw and stubble mulching by high pressure accelerating airflow. During the pneumatic seeding experiment, keeping a certain pneumatic seeding height HG and incident angle α between the accelerating tube and topsoil surface, high-pressure gas was injected from the upper apex of the air nozzle and ejected from the bottom of it, which a stable high-speed airflow was formed in the accelerator tube (the length of the accelerator tube is 600 mm and the diameter is 10 mm). Then wheat seeds were put into the seed entrance and absorbed at a high speed under the negative air pressure of the ejector, during which the rubber sleeve could protect wheat seeds from damaging. After mixing with airflow, wheat seeds were accelerated by high-speed air flow in the accelerating tube. Finally, the wheat seeds flew out and ripped into the soil at a certain incident angle and high pneumatic seeding velocity. At the same time, high-speed photography technology was used to study the parameters of pneumatic seeding velocity, vertical velocity and pneumatic seeding depth under six levels (15°, 30°, 45°, 60°, 75°, 90°) of incident angles, and pneumatic seeding experiments under five different accelerating air pressures of 0.2 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa and 1 MPa for each incident angle were carried out respectively. Pneumatic seeding experimental results showed that: For pneumatic seeding in soil without straw and stubble mulching, when the incident angle increases continuously, wheat seeds can achieve higher vertical component of pneumatic seeding velocity deeper and pneumatic seeding depth at the same accelerating air pressures, the probability of horizontal slip and bounce of wheat seeds after touching soil show an decreasing trend, and pneumatic seeding depth has a positive correlation with pneumatic seeding velocity under each incident angle. Moreover, wheat seeds show various pneumatic seeding depth and soil impact effect without damage after pneumatic seeding. When the incident angles and the vertical component of pneumatic seeding velocity were more than 45° and 25 m/s respectively, wheat seeds can be completely ripped into the soil and the emergence rate is more than 86%. The best pneumatic seeding effect achieved as incident angle is 90°. In order to realize wheat vertical pneumatic seeding in field operation, the horizontal component of pneumatic seeding velocity should be equal to the operating speed of seeder and the vertical component of pneumatic seeding velocity should be greater than 25 m/s, which the seeder operating speed shows positively and negatively correlated with pneumatic seeding velocity and incident angle, respectively. The experimental results can provide basic data and technical support for the development of non-contact wheat seeding equipment in rice-wheat rotation area. [ABSTRACT FROM AUTHOR]

Lemon (Citrus limon), a species of the genus Citrus, is an economically significant crop and extensively cultivated in Iran, especially in Fars Province. Very little information is currently available on the changes in the different forms of soil potassium under the influence of lemon tree plantations or the associated mineralogical changes. The objective of this study was to investigate the status of different forms of K and the transformation of K-bearing minerals in the rhizosphere in lemon orchards of varying ages. Results demonstrated that the amounts of soluble, available, exchangeable, and nonexchangeable K in the control were higher than those in the lemon orchards of all the age range studied. The highest reduction in the different forms of soil K was measured for the 50-year-old orchard. The nonexchangeable K was significantly lower in the 20- and 50-year-old lemon orchards as compared with the control soil. Soil potassium concentration was observed to decrease with increasing soil depth. Our findings also indicated that vermiculitization of illitic clay minerals occurred due to both root potassium uptake and root activities in the rhizosphere of lemon trees. Shallower soil depths in the orchards were found to contain a higher illite content, while the vermiculite and interstratified I/S content increased with depth, except in the case of the 5-year-old orchard. Our findings also show that soils under lemon orchards of different ages exhibit differences in their K availability and, further, that vermiculitization might take place as a result of long-term cultivation despite the application of potassium fertilizers. [ABSTRACT FROM AUTHOR]

The installation of jet grouting columns in fine-grained soils can cause significant disturbances to nearby structures, thereby undermining the reliability of this powerful technology. The high-pressure injection of large volumes of grouting materials coupled with the limited exhaust capacity of the boreholes often cause ground surface upheavals and lateral displacements. The problem appears particularly for horizontal columns injected at relatively shallow depths and in fine-grained soils. Systems employed to control the pressure in the injection cavity and fasten the spoil discharge represent an effective method to mitigate the ground disturbance. However, although the principle is well understood, there is no reliable analytical solution to predict ground movements caused by horizontal jet grouting and the resulting spoil discharge. This paper presents a simple calculation scheme to estimate ground movements induced by horizontal jet grouting. The method considers the jetting parameters, soil properties, and volume of discharged spoil. Further, a new equation is derived to calculate the radius of the plastic zone considering the discharged spoil. The proposed method is applied to interpret the observations obtained in two real case studies. The comparison of the calculation results and measured data confirms the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Despite the great importance of potassium applied as a fertilizer in the orange orchards, no information is currently available regarding the rate of potassium release from rhizosphere and the bulk soils of such trees. The objectives of this study were to investigate the weathering of micaceous minerals and their non-exchangeable K release and also, to examine the status of different forms of K in the rhizosphere and bulk soils of orange orchards with different ages in Darab, Fars Province. Samples were, accordingly, taken from the rhizosphere and bulk soils of orange orchards with the ages of 5, 10 and 20 years; also, virgin soils (control) were obtained from three soil depths including 0-30, 30-60, and 60-100 cm. Water soluble, exchangeable and nonexchangeable K, and the clay mineralogy of the soils were determined. The results demonstrated that the concentration of soluble and exchangeable K in the cultivated soils was less than that in the control soil and that the concentration of nonexchangeable K in the soils of 20-year-old orchards was less, than that in other soils. Soluble and exchangeable K values decreased with depth in all soils. Clay mineralogy investigation also showed that the quantity of illite decreased and that of smectite and illite-smectite increased as the age of orange trees was raised. With increasing the age of orange trees and root development, more potassium could be taken up from soil and more changes occurred in the soil minerals. In order to avoid a very high decline in the reserved K in the soils under orange trees, particularly in the orchards with older trees, K fertilization has to be taken more seriously based on the soil testing results. [ABSTRACT FROM AUTHOR]

Soil displacement is the most important performance indicator for seed openers, as it affects the uniformity of seeding depth. In this study, a hoe opener was modeled using Particle Flow Code in 3 Dimensions (PFC3D), a discrete element modeling software program. The objective was to simulate soil displacement in terms of soil throws. To validate the model, an air drill with hoe openers was tested in a field with clay soil at a working depth of 38 mm and travel speed of 8 km h-1. Soil throw resulting from the hoe opener was measured. To calibrate the model, a virtual soil shear test was created within PFC3D, and the output soil shear torque was compared to the torque measured in the same field. The result showed that the calibrated effective modulus, a critical micro-parameter of model particles, was 5.692 × 107 Pa. With this calibrated value, the simulated soil throws agreed well with the measured throws, with a relative error of 15%. The model was used to compare different hoe opener designs: single-shoot spread, double-shoot side-band, double-shoot paired-row, and tripleshoot openers. Among all these openers, the side-band opener resulted in the least lateral soil throw, and the paired-row opener resulted in the lowest vertical soil throw but the highest lateral throw. The developed model was effective for examining the effects of opener geometry on soil displacement. [ABSTRACT FROM AUTHOR]

Summary: We compared water and solute movement between a ridge and furrow geometry and that of flat soil with a mathematical model. We focused on the effects of two physical processes: root water uptake and pond formation on the soil surface. The mathematical model describes the interaction between solute transport, water movement and surface pond depth. Numerical simulations were used to determine how solutes of varying mobility and rates of degradation penetrated into the two soil geometries over a growing season. Both the ridge and furrow or flat soil geometries could reduce solute leaching, but this depended on several factors. Rain immediately after a solute application was a key factor in determining solute penetration into soil. In cases with delayed rain after a solute application, solutes in ridge and furrow geometries collected adjacent to the root system, resulting in reduced solute penetration compared to the flat soil geometry. In contrast, substantial rain immediately after a solute application resulted in ponding where water infiltration acted as the dominant transport mechanism. This resulted in increased solute penetration in the ridge and furrow geometry compared to the flat soil geometry. Highlights: We studied solute movement controlled by ponding in ridge and furrow and flat fields.We found the ridged soil could impede or increase leaching compared to the flat soil.Solute hot‐spots formed in ridge and furrow soil because of root water uptake.Time between solute application and rainfall is a key factor for solute penetration. [ABSTRACT FROM AUTHOR]

Variations in soil radon concentrations are a potential precursor of earthquake and volcanic events. However, the unclear migration and variation mechanisms of radon concentrations in soil still limit its effective application. To elucidate the temporal variation and its possible influence factors on radon concentrations at different soil depths, a case study was performed at a suburban site in Beijing. A long-term continuous measurement system consisting of ten radon-in-soil monitors at depths from 0.1 to 5.0 m and other meteorological sensors was employed. The monitoring was carried out from January 8th to July 29th, 2022, covering 3445 h in total. Radon concentrations generally increased with soil depth. Diurnal variation of soil radon concentrations at depths of 1.2 and 1.6 m in winter and spring was observed, and a negative correlation between the soil radon concentration and the residual air pressure was found. This finding indicates a possible air exchange channel between the soil and the atmosphere at the study site. In addition, the soil radon concentration at 4.0 m depth was unexpectedly lower than that of neighboring depths and was steady throughout the measurement period. This is attributed to a possible clay layer in the soil structure at 4.0 m depth. The results of this field study indicate that the complexity of temporal variation of soil radon concentrations should be considered for its application in predicting earthquake and volcanic events. • Continuous monitoring of radon concentrations in ten soil depths to 5.0 m. • Bi-periodic diurnal variation of radon concentrations at 0.8–3.0 m depth. • Negative correlation between radon concentration and air pressure. • Air exchange channel between soil and atmosphere might exist. [ABSTRACT FROM AUTHOR]

The exterior surfaces of cast iron pipes buried in clay soils for up to 129 years show clustering of pits of similar depth at progressively greater overall corrosion pit depth. Within experimental accuracy, the pit depth increments are approximately constant over the whole range of pit depth for each soil. They increase with lower soil pH and appear insensitive to other soil properties and to burial period. These new findings are interpreted relative to pitting electrochemical potential and compared with field observations for pitting in marine corrosion of steel. Implications for modelling maximum pit depth development are considered. [ABSTRACT FROM AUTHOR]

• Impact of timber residue management on soil arthropods is poorly understood. • Immediate impact on soil arthropod diversity did not differ among management types. • Soil arthropods partially recovered irrespective of management practice. • Soil biological activity recovered by ∼ 50 % after 6 months. • Long-term assessment is required to determine sustainable management practices. To sustainably manage soils, we need to understand the impact of management practices on soil biota. A major disturbance in commercial tree plantations is the management of the woody residue that remains in situ after harvesting. We examine the impact of different harvest residue management practices on soil biota in a forestry landscape in KwaZulu-Natal, South Africa on nutrient-rich clay soils. We assess four different management practices and unmanaged grassland at three time periods: prior to implementation of residue management, directly after implementation, and six months after implementation. Management practices are 1) on-site retention of unburned harvest residue, 2) residue removal off site, 3) high-intensity burning and 4) low-intensity burning of residue. We examine the response of ant and springtail taxonomic and functional diversity, assemblage composition, and soil biological activity. We also assess whether soil biological activity at different soil depths differs among treatments. Across all sites, all biotic responses declined in the post-treatment, but recovery of the focal arthropods after six months was low regardless of the type of residue management practice. At each time period, ant and springtail taxonomic and functional diversity showed no difference among management practices. Soil biological activity showed minor differences between practices after implementation overall, and at different soil depths, and recovery was similar between residue management practices after six months. After six months, soil biological activity recovered to ∼ 50 % in all sites. Thus, in the short term, soil biota in this region are not differentially impacted by different residue management practices, despite major variations in conditions. We recommend further assessments in different soil types and over a longer period to assess the full impact of slash management on these functionally important soil arthropods. [ABSTRACT FROM AUTHOR]

PHC pipe pile cooperated with jacked method is widely used in recent years. The excess pore water pressure of pile-soil interface caused during jacked PHC pipe driving would produce important effect on jacked pile construction and bearing characteristics. Two full scale jacked-in piles are penetrated into the clayey soil and studied by monitoring the law of generation and dissipation of excess pore water pressure. The law of excess pore water pressure with penetration depth and time is also analyzed. From this test results, excess pore water pressure of the pile-soil interface increases to the peak and then begins to decrease, but it remains large. The excess pore water pressure of S1 test pile pile-soil interface decreases from 201.4 kPa to 86.3 kPa, and decreases from 374.1 kPa to 114.3 kPa for S2 test pile. The excess pore water pressure of pile-soil interface rises first at the initial stage of consolidation, and it dissipates when the hydraulic gradient between pile-soil interface and soil around the pile disappears. The dissipation degree of excess pore water pressure reaches from 75% to 85%. The proposed solution provides certain engineering significance for jacked pile construction and bearing capacity design in the clayey foundation. • Through on-site monitoring of the distribution and dissipation of excess pore water pressure at the pile-soil interface, the stress characteristics of the pile-soil interface during the PHC pipe pile sinking process were studied. • The maximum ratio of excess pore water pressure of pile-soil interface to effective pressure of overlying soil is 1.08, and gradually decreases along the pile. • The excess pore water pressure at the pile-soil interface caused by pile sinking is approximately linearly increased with the depth of the soil. • Studying the generation and dissipation of excess pore water pressure at pile-soil interface is helpful to reveal the important characteristics and bearing capacity of pile-soil interface during pile-sinking. [ABSTRACT FROM AUTHOR]