Soil Volume Research Articles

Within-field extrapolation away from a soil moisture probe using freely available satellite imagery and weather data

Recognition of the importance of soil moisture information to the optimisation of water-limited dryland cereal production has led to Australian growers being encouraged to make use of soil moisture sensors. However, irrespective of the merits of different sensing technologies, only a small soil volume is sensed, raising questions as to the utility of such sensors in broadacre cropping, especially given spatial variability in soil water holding capacity. Here, using data collected from contrasting sites in South Australia and Western Australia over two seasons, during which either wheat or barley were grown, we describe a method for extrapolating soil moisture information away from the location of a probe using freely-available NDVI time series and weather data as covariates. Relationships between soil moisture probe data, cumulative NDVI (ΣNDVI), cumulative net precipitation (ΣNP) and seasonal growing degree days (GDD) were significant (P < 0.0001). In turn, these could be used to predict soil moisture status for any location within a field on any date following crop emergence. However, differences in ΣNDVI between different within-field zones did not fully explain differences in the soil moisture from multiple sensors located in these zones, resulting in different calibrations being required for each sensor or zone and a relatively low accuracy of prediction of measured soil moisture (R2adj ~ 0.4–0.7) which may not be sufficient to support targeted agronomic decision-making. The results also suggest that at any location within a field, the range of variation in soil moisture status down the soil profile on any given date will present as greater than the spatial variation in soil moisture across the field on that date. Accordingly, we conclude that, in dryland cereal cropping, the major value in soil moisture sensors arises from an enhanced ability to compare seasons and to relate similarities and differences between seasons as a guide to decision-making.

Cohort Marsh Equilibrium Model (CMEM): History, Mathematics, and Implementation

AbstractMarsh accretion models predict the resiliency of coastal wetlands and their ability to store carbon in the face of accelerating sea level rise. Most existing marsh accretion models are derived from two parent models: the Marsh Equilibrium Model, which formalizes the biophysical relationships between sea level rise, dominant macrophyte growth, and elevation change; and the Cohort Theory Model, which formalizes how carbon mass pools belowground contribute to soil volume expansion over time. While there are several existing marsh accretion models, the application of these models by a broader base of researchers and practitioners is hindered because of (a) limited descriptions of how empirically derived ecological mechanism informed the development of these models, (b) limitations in the ability to apply models to geographies with variable tidal regimes, and (c) a lack of open‐source code to apply models. Here, we provide for the first time an explicit description of a mathematical version of the Cohort Theory Model and a numerical version of a combined model: the Cohort Marsh Equilibrium Model (CMEM) with an accompanying open‐source R package, rCMEM. We show that, through this “depth‐aware” model, we can capture how tidal variation impacts broad patterns of marsh accretion and carbon sequestration across the United States. The application of this model will likely be imperative in predicting the fate and state of coastal wetlands and the ecosystem services they provide in an era of rapid environmental change.

Traditional gold mining in the highlands of Ethiopia: Its effect on soil loss and possible reclamation measures

Traditional gold mining (TGM) is among the off-farm income sources of smallholder communities in the highlands of Ethiopia. However, information on their impact on land degradation, taking soil loss as a key indicator, was scant. Hence, this study aimed at i) analyzing local communities’ attitudes toward TGM practice, ii) TGM impact on soil loss, and iii) possible restoration measures for the degraded gold-mined landscapes. For the evaluation of community perceptions, 96 beneficiaries were selected from three gold mining sites following stratified random sampling techniques. Soil loss measurement was done through measurement of i) the mass of soil excavated and transported to the river (TR) from 96 individuals and ii) soil volume excavated in 45 excavated soil pits (EP). Descriptive statistics and one-way ANOVA were used to analyze soil loss data, while community perception was analyzed qualitatively. The survey results indicated that the average soil loss from TR and EP were 6,075.97±8.9 t ha-1 yr-1 and 32,549.99±753.68 t ha-1, respectively. The magnitude of soil loss also showed a significant (p&lt;0.001) difference among the three sites. Due to a lack of awareness and hiding the reality, most of the gold miners believe that TGM practice has no negative impact on the soil resource, and no post-mined reclamation strategy is implemented. It can be concluded that the existing TGM practices are not done in an environmentally friendly approach and result in adverse soil loss. Hence, stabilizing the topography of the mined sites via backfilling of mined pits and topsoil conservation and amendment measures can be suggested.

Evaluating the role of soil properties on volumetric shrinkage characteristics of marine and inland clays

ABSTRACT Clayey soils that exhibit swelling and shrinkage behaviour have paved the way for various engineering problems such as foundation failure, slope stability issues, failure of earthen dams, cracking of clay liners, etc. The shrinkage behaviour of soil is often quantified by employing various direct and indirect experimental techniques to establish the Soil Shrinkage Curve (SSC), a relationship between soil volume change and moisture content. However, SSC can reveal only the overall volume change and does not exclusively comprehend the variation of volumetric shrinkage in linear and radial directions. Hence, a series of desiccation tests were performed on marine and inland clayey soils of different consistencies to evaluate the contribution of volumetric shrinkage in these orientations. From this study, it has been observed that the linear component of volumetric shrinkage was higher for soil samples with a consistency state between 1.0 and 1.5 times the liquid limit. However, the radial component of volumetric shrinkage was found to be higher at the end of the desiccation test for soils with an initial moisture content at or below the liquid limit. Furthermore, the results obtained from the present study have been utilised to establish the influence of soil properties on radial, linear, and total volumetric shrinkage.

N2 Fixation, N Transfer, and Land Equivalent Ratio (LER) in Grain Legume-Wheat Intercropping: Impact of N Supply and Plant Density.

Intercropping legumes with cereals can lead to increased overall yield and optimize the utilization of resources such as water and nutrients, thus enhancing agricultural efficiency. Legumes possess the unique ability to acquire nitrogen (N) through both N2 fixation and from the available N in the soil. However, soil N can diminish the N2 fixation capacity of legumes. It is postulated that in intercropping, legumes uptake N mainly through N2 fixation, leaving more soil N available for cereals. The latter, in turn, has larger root systems, allowing it to explore greater soil volume and absorb more N, mitigating its adverse effects on N2 fixation in legumes. The goal of this study was to evaluate how the supply of N affects the intercropping of faba beans (Vicia faba L.) and peas (Pisum sativum L.) with wheat under varying plant densities and N levels. We measured photosynthetic traits, biomass production, the proportion of N derived from air (%Ndfa) in the shoot of the legumes, the N transferred to the wheat, and the land equivalent ratio (LER). The results revealed a positive correlation between soil N levels and the CO2 assimilation rate (An), chlorophyll content, and N balance index (NBI) in wheat. However, no significant effect was observed in legumes as soil N levels increased. Transpiration (E) increased in wheat intercropped with legumes, while stomatal conductance (gs) increased with N addition in all crops. Water use efficiency (WUE) decreased in faba beans intercropped with wheat as N increased, but it showed no significant change in wheat or peas. The shoot dry matter of wheat increased with the addition of N; however, the two legume species showed no significant changes. N addition reduced the %Ndfa of both legume species, especially in monoculture, with peas being more sensitive than faba beans. The intercropping of wheat alleviated N2 fixation inhibition, especially at high wheat density and increased N transfer to wheat, particularly with peas. The LER was higher in the intercropping treatments, especially under limited N conditions. It is concluded that in the intercropping of wheat with legumes, the N2 fixation inhibition caused by soil N is effectively reduced, as well as there being a significant N transfer from the legume to the wheat, with both process contributing to increase LER.

The Influence of Differences in Volume Density and Blotong Application on the Physical Properties of Ultisol Soil and Sweet Potato Plant Growth

This study investigates the effects of variations in volume density and blotong application on the physical properties of Ultisol soil and the growth of sweet potato plants. The main objectives of the research are to assess how different levels of volume density and blotong application affect soil characteristics and plant growth. The study employs a qualitative approach, incorporating literature review and library research to explore existing knowledge and methodologies related to soil physics and plant physiology. The research involves conducting experiments where Ultisol soil samples with varying volume densities are treated with different levels of blotong application. Parameters such as soil bulk density, porosity, water retention capacity, and sweet potato plant growth parameters are measured and analyzed. The results reveal significant correlations between volume density, blotong application, and soil physical properties. Higher volume density generally leads to decreased soil porosity and water retention capacity, while blotong application demonstrates a positive impact on soil structure and plant growth. The findings highlight the importance of optimizing soil volume density and implementing blotong application techniques to enhance soil fertility and support healthy plant growth, particularly in Ultisol soil conditions. In conclusion, this research contributes valuable insights into sustainable agricultural practices for improving soil quality and crop productivity, emphasizing the significance of tailored management strategies for different soil types and crops.

Performance investigation of highway bridge pier columns under the sequential effects of fire followed by vehicle collision and subsequent air blast: A numerical investigation

Historically, it has been demonstrated that bridges may be vulnerable to fire, and in many circumstances, resulting damage might not be apparent, and bridges could maintain acceptable levels of serviceability. In the absence of proven assessment tools and given the limited research that addresses bridge fire, research that better understands response and strives to improve highway bridge resiliency to fire is needed. Extending the work carried out during an earlier research stage, the present study focused on investigating performance of bridge pier columns that survive fire under coupled vehicle collision and air blast. Numerical models of single reinforced concrete columns supported by a pile foundation system and surrounded by air and soil volumes were created using LS-DYNA. As explicit solvers such as those available in LS-DYNA are infrequently used for fire analysis, an indirect two-step approach that integrated heat transfer and structural analyses was developed and validated against published fire-induced impact and blast test results. A parametric study that examined the effects of various fire exposure conditions and column diameters was completed. Performance was comprehensively assessed based on various structural response parameters, which included failure modes, lateral displacement, residual axial capacities, and shear demand-to-capacity ratios. Column damage was then categorized into six levels to qualitatively assess column performance under the aforementioned multi-hazards. The developed modeling approach was shown to be viable, and results indicated that larger column diameters could potentially remain in service in their final damage states after being repaired for fire durations of less than 120 min.

Effects of soil on the development, survival, and oviposition of Culex quinquefasciatus (Diptera: Culicidae) mosquitoes

BackgroundWater quality is known to influence the development and survival of larval mosquitoes, which affects mosquito-borne pathogen transmission as a function of the number of mosquitoes that reach adulthood and blood feed. Although water properties are known to affect mosquito development, few studies have investigated the link among soil properties, water quality, and mosquito development. Given the large number of ground-breeding mosquito species, this linkage is a potentially important factor to consider in mosquito ecology. In this study, we explored the effects of different soils on multiple life history parameters of the ground-breeding mosquito species Culex quinquefasciatus (Diptera: Culicidae).MethodsCx. quinquefasciatus larvae were reared in water combined with different soil substrates (sandy, silt, or clay loam textures) at increasing soil to water volume ratios, with and without the addition of organic matter (fish food). Gravid mosquitoes were offered different soil–water extracts to investigate soil effects on oviposition preference.ResultsWithout the addition of organic matter, larval survival and development differed significantly among waters with different soil textures and volumes of substrate. Mosquitoes in water with clay loam soil survived longer and developed further than mosquitoes in other soil waters. Larvae survived for longer periods of time with increased volumes of soil substrate. Adding organic matter reduced the differences in larval survival time, development, and pupation among soil–water extracts. Adult female mosquitoes oviposited more frequently in water with clay loam soil, but the addition of organic matter reduced the soil effects on oviposition preference.ConclusionsThis study suggests soil composition affects larval mosquito survival and development, as well as the oviposition preference of gravid females. Future studies could differentiate abiotic and biotic soil features that affect mosquitoes and incorporate soil variation at the landscape scale into models to predict mosquito population dynamics and mosquito-borne pathogen transmission.Graphical

Changes in preferential flow caused by root effects in black locust plantations of different stand ages in the semi-arid region of the Loess Plateau

Preferential flow significantly influences regional water cycles, and affecting surface and subsurface runoff processes. By comparing soil infiltration characteristics across various forest ages, it can be evaluated how artificial black locust forests on the Loess Plateau contribute to the resilience of soil and water conservation. In this study, we analyzed the spatial distribution characteristics of roots of black locust plants using field investigations and statistical analyses and determined the effects of the root characteristics on the preferential flow in the semi-arid of the Loess Plateau, China. The results showed that the root biomass, root length density, and root volume ratio of young forests were significantly lower than those of middle-aged and mature forests (P < 0.05), and root characteristic parameters varied significantly among different root diameters and soil layers.. The average volume of decayed root channels in mature forests, accounting for approximately 0.16 % in a unit volume of soil, was 3.1 times that of young forests and 4.9 times that of middle-aged forests. Preferential flow increased with forest age in artificial black locust forests. 2–5 mm, 30–40 mm and > 50 mm roots promoted preferential flow to varying degrees, while roots of 5–15 mm inhibited the preferential flow. < 2 mm, 10–30 mm and 40–50 mm roots has no effect on preferential flow (P > 0.05). The size and density of decayed root channels significantly improve soil preferential flow, and the differences among forest ages are linked to the network created by rotten roots. These findings indicate that living roots of different diameters and decayed roots contribute to soil preferential flow to varying extents. The results provided a conceptual basis for understanding the potential impact of vegetation roots on surface runoff during the vegetation restoration ecosystems process in the Loess Plateau.

A new approach for drought index adjustment to clay-shrinkage-induced subsidence over France: advantages of the interactive leaf area index

Abstract. Clay shrinkage, which consists of a reduction in the volume of clay soils during dry periods, can affect buildings and cause subsidence damage. In France, losses due to subsidence are estimated at more than EUR 16 billion for the period 1989–2021 (CCR, 2021) and are expected to increase under the effect of climate warming. This work aims to improve the current understanding of the conditions triggering subsidence by proposing an innovative drought index. We use a daily soil wetness index (SWI) to develop a new annual drought index that can be related to subsidence damage. The SWI is derived from simulations of soil moisture profiles from the interactions between soil–biosphere–atmosphere (ISBA) land surface model developed by Météo-France. The ability of the drought index to correlate with insurance claim data is assessed by calculating the Kendall rank correlation over 20 municipalities in France. The insurance data, aggregated by year and municipality, are provided by the Caisse Centrale de Réassurance (CCR). A total of 1200 configurations of the drought index are considered. They are generated by combining different calculation methods, ISBA simulation settings, soil model layers, and drought percentile thresholds. The analysis includes a comparison with the independent claim data of six additional municipalities and with a record of official “CatNat” (the French national natural disaster compensation scheme) decrees, useful for the analysis. The best results are obtained for drought magnitudes based on SWI values of the 0.8-to-1.0 m deep soil layer, an ISBA simulation with interactive leaf area index (LAI), and consideration of low drought SWI percentile thresholds. Comparison with claim data shows that drought magnitude is able to identify subsidence events while being spatially consistent. This drought magnitude index provides more insight into subsidence triggers while benefiting from advanced land surface modeling schemes (interactive LAI, multilayer soil). This work paves the way for more reliable damage estimates.

Coupled heat and water transfer in heterogeneous and deformable soils: Numerical model using mixed finite element method

We present a generic model framework for coupled heat and water transfer (CHWT) in deformable (non-rigid) soils with spatial variations of soil properties. The model backbone is a mixed finite element method (FEM), which solves the Philip and de Vries (1957) CHWT model and achieves conservation of mass and energy on both local and global scales. Spatial variations occur in soil hydraulic and thermal properties due to transient water content and temperature distributions. Based on the mixed FEM scheme, a gradient measure and a clustering model (“k-means”) are proposed to trace the regions with large spatial variations of soil properties, and an adaptive mesh refinement technique is developed to improve the spatial resolution and simulation accuracy. Deformation perturbates local soil topography and alters transient soil water and temperature regimes in the deformed regions. A quasi-static deformation model is presented, and the deformation effects are incorporated into the mixed FEM scheme. When external load exists, soil deformation is simulated with an updated Lagrangian formulation, and the local water content and temperature variations due to soil volume changes are also updated in the CHWT model. Numerical examples, including thermally induced soil water transfer and water infiltration, illustrate the model ability to provide plausible CHWT results, especially the refined solutions near the wetting fronts and the water content and temperature distributions when the soil is deformable. In conclusion, the proposed model framework provides an effective pipeline to incorporate and process the spatial variations of soil properties and soil deformation in CHWT simulations.

Physical, Chemical and Compaction Characteristics of Slightly Weathered Tephras of New Zealand

The North Island of New Zealand is a region of high volcanic activity, with significant eruptions over the past. Analogous to past events, future volcanic eruptions would produce a considerable volume of ash and granular soils, covering widespread areas and raising concerns for their disposal and storage. Such deposits, primarily airfall tephra, could be potentially used in geotechnical engineering applications such as foundations, roadway embankments and land reclamations. However, before their use as structural fills can be recommended, detailed laboratory investigations of their physical, chemical, compaction, and geotechnical engineering properties (strength, compressibility, collapsibility, liquefaction potential, etc.) must be conducted. Different tephra deposits can be products of different eruptions, so chemical composition analyses can be combined with the physical, compaction, and engineering properties to characterize such deposits. Accordingly, this paper provides useful insights from physical (grain size, specific gravity, and morphology), chemical (elemental and mineralogy using X-ray fluorescence and X-ray diffraction), and compaction tests (maximum dry density, optimum water content, and particle breakage) for eleven selected volcanic tephra samples sourced from the North Island of New Zealand in the Rotorua, Taupo, and Auckland regions.

Deciphering Soil-Plant and Soil-Insect Interactions: A Mathematical Modeling Approach

Abstract The Pev and Rv functions were introduced as a way of summarizing the mechanical phenomenon of root-soil interactions and the effect of root growth on soil volume. The Mohr-Coulomb criterion was applied to the Rv function to demonstrate the relationship between root morphology, soil mechanical properties, and soil stability. The theory of elasticity and plasticity was applied in the analysis of the Bio-Geo Interface, which showed that the force F generated by the roots increased with time due to the growth of the roots and the increase in their volume. The forces acting on the Bio-Geo Interface were represented mathematically through the use of vector arithmetic, which helped to calculate the direction of the forces acting on the system. The Pev function was used to study the evolution of the plant and how it affected the Rv function. The results showed that the interplay between plant growth and soil mechanics is crucial in understanding the behavior of the Bio-Geo Interface, and can provide valuable insights into the interactions between plants and soil in natural and engineered systems. In the study of soil-insect interaction, a mathematical function, Iev, was proposed to represent the insect’s evolution in the soil environment. The function takes into account factors such as food sources and void ratio, which are important indicators of the biological and geotechnical aspects of the soil respectively. Despite the potential impact of insects on the soil environment, it has been concluded that their force resulting from their movement and behavior is negligible according to theories of elasticity and plasticity. This means that the impact of insects on the soil is minimal and does not significantly affect the soil’s mechanical properties. However, the biological aspects of the soil, such as food sources, remain important factors in the study of insect evolution in the soil environment.

A numerical investigation on the effect of rotation on the cone penetration test

The cone penetration test (CPT) is one of the most popular in situ soil characterization tools. However, the test is often difficult to conduct in soils with high penetration resistance. To resolve the problem, a rotary CPT device has recently been adopted in practice by rotating the rod to increase the penetrability, particularly in deep dense sand. This study investigates the underlying mechanism of the rotation effects from a micromechanical perspective using models based on the discrete element method. With rotation, the cone penetration resistance ( qc) decreases by up to 50%, while the cone torque resistance ( tc) increases gradually. These results are also used to successfully assess existing theoretical solutions. The mechanical work required during penetration is observed to keep rising as the rotational velocity increases. Microscopic variables including particle displacement and velocity field show that rotation reduces the volume of disturbed soil during penetration and drives particles to rotate horizontally, while contact force chain and contact fabric indicate that rotation increases the number of radial and tangential contacts and the corresponding contact forces, forming a lateral stable structure around the shaft, which can reduce the force transmitted to the particles below the cone, thus decreasing the vertical penetration resistance.

Back analysis of shear strength parameters of slope based on BP neural network and genetic algorithm

AbstractEfficient and accurate acquisition of slope shear strength parameters is the key to slope stability analysis and landslide prevention engineering design. This paper establishes a back analysis method based on uniform design, artificial neural network, and genetic algorithm. It can obtain the shear strength parameters of slopes based on information such as the radius and center coordinates of the slip surface obtained from on‐site investigations. This method has been applied to engineering practice. The research results indicate that the stability of the waste dump slope is most sensitive to the response of the internal friction angle of the loose body, followed by cohesion, and least sensitive to the response of the soil volume weight. This method can effectively reduce the number of network training samples and efficiently and quickly determine the initial weights of the BP (abbreviation for back‐propagation) neural network. This method can efficiently and quickly conduct back analysis to obtain the shear strength parameters of slopes. Using the obtained shear strength parameters for slope stability calculation, the most dangerous slip surface abscissa error, ordinate error, and slip surface radius error are only 3.59%, 0.95%, and 1.83%. It is recommended to promote the back analysis method of shear strength parameters in engineering practice in the future.

Reducing the dynamic impact of a landslide on buildings and transport structures in the village of Toktogul, Uzgen district of the Kyrgyz Republic

In the Kyrgyz Republic, there is a significant increase in landslide activity against the backdrop of ongoing climate change, especially in the southern mountainous regions of the country. The volume of soil during a landslide in this region can reach tens and hundreds of thousands of cubic meters, and in some cases more. The rate of landslide displacement ranges from several meters per year to several meters per second. The purpose of this study is to unload the landslide area to protect the population, roads and other structures of the village of Toktogul, Uzgen district of the Kyrgyz Republic. This landslide area was studied on the basis of field research on the ground and the results of desk work. The sliding of soil masses in the area can cause destruction and debris of residential and administrative buildings, roads and power lines, as well as injury and death. Considering the equilibrium of the system of forces acting on the subsidence soil mass of the slope section and analyzing them, measures for unloading the landslide body in this section are proposed. The proposed longitudinal profiles of drainage channels to reduce the moisture content of subsidence soil and transverse profiles of developed soil to reduce the weight of subsidence soil are presented. Based on the results of processing research data and analysis, it is recommended to reduce the weight of unstable (subsidence) soil by stepwise development along the slope of the site and transporting it up to 5 km for subsequent brick production. It is also recommended to protect subsidence soil from waterlogging by installing drainage channels. Based on the results of the research, a real project was developed to protect the site from landslides near the village of Toktogul. The proposed measures make it possible to reduce the risk of a landslide in the area under consideration using methods and technical means that are inexpensive and accessible to government agencies and local administrations.

Estimating external exposure from different source geometries in soil contaminated by gamma-ray emitting radionuclides: A computational model combining Monte Carlo simulation and mathematical transformation

A computational model is developed to estimate the external exposure to an arbitrary scenario describing the spatial distribution of the source in a contaminated soil by gamma-ray emitting radionuclides released after nuclear activities. This model welds together a Monte Carlo simulation approach and a mathematical transformation based on Tait–Bryan angles formalism. For Monte Carlo simulation, a source depth dependent optimized geometry describing a semi-infinite soil-cover-air medium of propagation is mathematically derived based on the physical attenuation of the gamma ray in matter. For each primary energy of interest, the proposed mathematical transformation is applied to the output of the Monte Carlo simulation to define the overlapping region between the contaminated soil volume and the proposed optimized volume. This approach made it possible to estimate the human external exposure associated with the scenario under investigation. Several scenarios were studied. The flux energy distribution of the detected radiation and the corresponding dose quantities are calculated. A benchmarking test with a direct Monte Carlo simulation and a comparison with published results in the literature show good agreement validating therefore the presented model.

Shifts from an extensive to an intensive root nutrient‐acquisition mode with stand development of three Pinus species

Abstract Plant roots employ diverse strategies to acquire soil nutrients, including direct nutrient uptake through absorptive fine roots and root hairs, scavenging nutrients by forming symbioses with mycorrhizal fungi, and mining nutrients by releasing root exudates. However, whether these three strategies are differently coordinated among phylogenetically closely related tree species and how this coordination shifts with stand development remains largely unclear. To fill these knowledge gaps, we measured 13 root morphological, architectural, physiological and mycorrhizal traits tightly related to nutrient‐acquisition of three Pinus species (P. sylvestris var. mongolica, P. densiflora and P. tabuliformis) at young (20‐year‐old) and mature (50‐year‐old) stages planted in nutrient‐impoverished sandy soils, in Northeast China. We found that young trees had thinner absorptive fine roots and a higher specific root length than mature trees across three Pinus species, indicating that roots become morphologically less efficient in ‘do it yourself’ scavenging nutrients during stand development. Moreover, young stands had greater root length density and root area index, and mature stands had faster root‐exudation rates, suggesting that young stands rely more on expanding soil volumes to scavenge nutrients and mature stands depend more on root exudation to ‘mine’ nutrients. The three Pinus species exhibited different nutrient‐acquisition strategies at the mature stage; P. densiflora had higher root length density and root area index, and the other two Pinus species had greater ectomycorrhizal colonization rates. Synthesis. Our findings highlight that phylogenetically closely related tree species may exhibit different nutrient‐acquisition strategies and suggest a shift from an extensive nutrient‐acquisition mode depending more on absorptive fine roots to an intensive nutrient‐acquisition mode relying more on root exudation during stand development.

Non-Destructive Evaluation of Material Stiffness beneath Pile Foundations Tip Using Harmonic Wavelet Transform

Pile foundations are used to support superstructures and play an important role in the safety of these structures. The performance of pile foundations generally depends on the conditions of the pile itself and the material under the pile tip(i.e., bottom), especially for end-bearing piles installed in soft soil volumes. Therefore, to assess the performance of existing pile foundations, it is crucial not only to evaluate the structural integrity of the pile itself, but also to assess the ground conditions, such as subsoil stiffness beneath the pile foundation tip. Accessing the subsoil beneath the pile foundation tip is highly challenging in the field. Hence, there is a need for the development of non-destructive pile evaluation methods that allow the assessment of subsoil stiffness beneath the pile tip without direct access to the subsoil. Various non-destructive methods have been developed for pile performance assessment. However, these conventional non-destructive methods are primarily designed for assessing the structural integrity of the pile itself, and there are no existing non-destructive pile integrity testing methods applicable to evaluate the subsoil stiffness beneath the pile tip. In this study, a non-destructive method is developed to evaluate the subsurface soil stiffness beneath pile tip without direct access. The proposed method involves applying impact loading to the easily accessible pile head and measuring the elastic waves propagated within the pile foundation due to the impact loading. These wave signals are then recorded at the pile head. The measured time–history signals are decomposed using harmonic wavelet transform. This allows the obtainment of well-defined magnitude and phase information over time for various individual frequency components composing the wave. In this study, a method is proposed to assess the stiffness of the subsoil beneath the pile tip by simultaneously utilizing the magnitude and phase information of the measured signals obtained through harmonic wavelet transform. To facilitate this, a step-by-step data analysis procedure for evaluating the subsoil stiffness beneath the pile tip is introduced. To validate the proposed method, numerical simulations were conducted using ABAQUS. The experimental data obtained from the numerical simulations were processed using the proposed method to assess the subsoil stiffness beneath the pile. The determined subsoil stiffness was then compared with the exact soil stiffness used in the numerical simulation to evaluate the validity of the proposed method. Through this analysis, the proposed method demonstrated its effectiveness in assessing the subsoil stiffness beneath piles tip installed in weak soil volume.

Совершенствование решения задач оптимизации размещения посевов сельскохозяйственных культур в севооборотах хозяйств Белгородской области с учётом интенсивности смыва почвы

The article proposes a new way to solve the problem of optimizing the placement of agricultural crops on eroded lands in protective crop rotations. Optimality criteria for the problem: the volume of the washed-off soil should strive to a minimum. The required variables – the areas are given as a percentage of the total arable land area and are limited to minimum and maximum values. For the new method, a detailed description of the database compilation matrices in Microsoft Excel and the "Excel Solver" (Solution Search) application add-in is provided. The methodology for calculating the potential soil washout under agricultural crops in crop rotations has been revised, depending on the availability of crops on arable land during the snowmelt period. A unified formula has been developed for washing away soil under spring and winter crops. Keywords: OPTIMIZATION PROBLEMS, STRUCTURE OF ACREAGE, EROSION CONTROL ORGANIZATION OF THE TERRITORY, ECONOMIC AND MATHEMATICAL MODEL, WATER EROSION OF LAND, SOIL FLUSHING