Tillage operation aims to create a favorable environment for seed germination of agricultural crop production practices. Physio-mechanical properties of soil directly affecting soil behaviors and determinants in initial conditions affecting soil failure. An absence in understanding how soil physio-mechanical properties affect agrotechnical operations at different tillage depths, especially in study area, and lacks insights into their associations and practical implications for optimizing tillage and soil health. This study presents an experimental investigation of the physio-mechanical properties of agricultural soil in Bukito Kebele, Loka Abaya woreda of Sidama Regional state, Ethiopia. The objective was to identify these properties under varying agro-technical soil depth conditions. Randomized Complete Block Design (RCBD) field experimental design was spotted to take soil samples using appropriate sample equipment and further lab analysis was conducted. Loka Abaya farm soil is loam, offering balanced texture for drainage, water retention, and nutrient availability. Moisture content reaches a maximum of 24.36%, with a linear relationship between soil depth and moisture content. The Atterberg limits of the soil (LL: 37.5-40%, PL: 25-27.5%, PI: 10-15%) indicate low plasticity and low clay content, consistent with loamy or silty soils. The results also show that soil cohesion is low in the topsoil (surface layers) but increases significantly at depths of 10-15 cm. Soil resistance decreases with depth due to reduced compaction and increased pore space in subsurface layers. Bulk density peaks at 1.28 g/cm3 at 10 cm depth due to high organic matter decomposition, then decreases to 1.20 g/cm3 at 15-20 cm, likely from reduced organic matter and root activity in subsurface layers. Correlations analysis reveals that soil moisture strongly increases with depth (r = 0.99, p < 0.01), indicating that deeper tillage may be necessary in arid regions to access moist soil layers. Sandy soils, which show a strong link between plastic limit and sand percentage (r = 0.97, p < 0.01), require adequate moisture during tillage to prevent erosion. Moist, cohesive soils are less compacted (r = - 0.92, p < 0.05) and easier to till, while cohesive soils resist penetration (r = - 0.90, p < 0.05), highlighting the need for efficient tillage equipment to minimize energy use. Overall, soil moisture, texture, and cohesion are critical factors for optimizing tillage practices and enhancing soil health. The study's site-specific nature limits its broader applicability, its focus on physical properties few mechanical property, overviews chemical and biological aspects, and further research is required to understand the long-term impacts of tillage on soil structure and productivity.

This study investigates the mechanical properties and damage processes of cement-consolidated soils with Pisha sandstone geopolymer under impact loading using the Hopkinson lever impact test. The mechanical properties of cement-cured soils containing Pisha sandstone geopolymer were examined at various strain rates. The relationship between strain rate and strength of the geopolymer-cemented soil was established. As the strain rate increased, the coefficient of power increase for the Pisha sandstone geopolymer cement-cured soil initially rose before gradually stabilizing. The pore structure of the crushed specimens was analyzed using Mercury intrusion porosimetry. Based on the observed pore changes under impact loading, the pore intervals of the geopolymer-cemented soil were defined. A fitting model linking strain rate and porosity was developed. As strain rate increased, the porosity of the specimens first increased and then decreased, with larger internal pores gradually transforming into smaller ones. The highest porosity was observed at a strain rate of 64.67 s- 1. Crushing characteristics of the cement-cured soils under impact loading were determined through sieving statistics of the crushed particles. The average particle size of the fragments decreased as the strain rate increased. The fractal dimension initially decreased and then increased with the rise in strain rate, reaching its lowest value at a strain rate of 64.67 s- 1. Based on the dynamic mechanical properties, microscopic porosity, and fracture characteristics, the critical strain rate and damage form for cement-consolidated soils with Pisha sandstone geopolymer under impact loading were determined. This study offers valuable insights for the practical application of Pisha sandstone geopolymer cement-cured soils in engineering.

True triaxial tests were conducted on artificially frozen sand. The effects of the intermediate principal stress coefficient, temperature and confining pressure on the strength of frozen sand were studied. The stress-strain curves under different initial conditions indicated a strain hardening. In response to increases of either the intermediate principal stress coefficient or the confining pressure or to a decrease of temperature, the strength typically increased. Furthermore, a new strength criterion was proposed to describe the strength of artificially frozen sand under a constant b-value stress path, combining the strength function in the p-q and pi planes. Considering the low confining pressure, the strength criterion in the p-q plane fitted the linear relationship in the parabolic strength criterion well. The strength criterion in the pi plane was combined with stress invariants, and a new strength criterion was established. This criterion considers unequal tension and compression strength, and integrates temperature. Test results indicated its validity. All parameters of the strength criterion could be easily determined from the triaxial compression and triaxial tensile tests.

Enhancing the structural stability of Pisha sandstone soil is an important measure to manage local soil erosion. However, Pisha sandstone soil is a challenging research hotspot because of its poor permeability, strong soil filtration effect, and inability to be effectively permeated by treatment solutions. In this study, by adjusting the soil water content to improve the spatial structure of the soil body and by conducting unconfined compressive strength and calcium ion conversion rate tests, we investigated the effect of spatial distribution differences in microbial-induced calcium carbonate deposition on the mechanical properties of Pisha sandstone-improved soil in terms of the amounts of clay dissolved and calcium carbonate produced. The results demonstrate that improving the soil particle structure promotes the uniform distribution of calcium carbonate crystals in the sand. After microbial-induced carbonate precipitation (MICP) treatment, the bacteria adsorbed onto the surface of the Pisha sandstone particles and formed dense calcium carbonate crystals at the contact points of the particles, which effectively enhanced the structural stability of the sand particles, thereby improving the mechanical properties of the microbial-cured soils. The failure mode of the specimen evolved from bottom shear failure to overall tensile failure. In addition, the release of structural water molecules in the clay minerals promoted the surface diffusion of calcium ions and accelerated the nucleation and crystal growth of the mineralization products. In general, the rational use of soil structural properties and the synergistic mineralization of MICP and clay minerals provide a new method for erosion control in Pisha sandstone areas.

This study examines the behavior of anisotropically consolidated granular assemblies under undrained cyclic true triaxial loading paths. To achieve this, the Discrete Element Method (DEM) is conjugated with the Coupled Fluid Method (CFM) to account for fluid-solid interaction in undrained conditions. The examined loading paths include two phases: anisotropic consolidation and undrained cyclic true triaxial loading. During consolidation, samples are sheared at various Lode angles to reach a spectrum of initial static shear stress levels. In the second stage, undrained cyclic loading is applied with constant shear stress amplitudes at various Lode angle values. The results indicated that the monotonic and cyclic Lode angle, initial static shear stress, and amplitude of deviatoric stress have pronounced effects on the secant shear modulus degradation and the rate of excess pore water pressure generation of granular assemblies. In tandem with macro-scale observations, the evolution of the microstructure within assemblies is analyzed using the coordination number, redundancy index, inter-particle contact fabric tensor, and particle orientation fabric tensor. The micro-scale findings confirm that the anisotropy induced by changes in the loading direction significantly impacts the shear strength of the assemblies. Additionally, the fabric of assemblies aligns along the preferential direction corresponding to the major principal stress, influencing the dilative response.

Soil nitrogen-hydrolyzing enzymes catalyzes a key rate-limiting step in regulating the circulation of soil nutrient elements. The response of soil nitrogen (N)-hydrolyzing enzyme activities to environmental changes has been investigated in different geographic scales or ecosystems. Global warming has increased the frequency of soil freeze-thaw (FT) events, resulting in drastic changes in soil enzyme activities. Clarifying the changes in soil N-hydrolyzing enzymes under freeze-thaw conditions is essential for improving the N cycling and utilization efficiency in soil. However, how soil N-hydrolyzing enzymes respond to FT remains unclear. This study was aimed to analyze the influence of FT on soil N-hydrolyzing enzyme activity in Mollisols. The results showed that soil physicochemical properties and enzyme activities were changed after freeze-thaw events, and freeze-thaw temperature (FTF) had a greater impact on these properties than the number of freeze-thaw cycles (FTC). Correlation analysis showed that total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and pH were the major factors affecting enzyme activities in FT events. Soil N-hydrolyzing enzyme activity was mainly regulated by environmental factors, which can directly and indirectly affect the soil enzyme activity. In the soil ecosystem, pH, TOC, TN and TP were important factors in counteracting damage to enzyme activity from FT effects and a suitable environment and adequate nutrients can limit damage to enzymes from FT events. The findings will better predictions the changing patterns of climate change on soil N-hydrolyzing enzyme activity.

Modifying lateritic soils, which are widely distributed in humid and rainy regions around the world, for embankment construction is a practical necessity for highway and railway projects. These embankments are susceptible to infiltration of rainfall, wetting and vibration from earthquakes and traffic. Further study is required to investigate the dynamic response characteristics of these embankments under combined action of wetting and vibration. Two scaled-down physical models of embankments were built: one with unmodified lateritic soils, which are typical soils with high liquid limit in central-southern China, and the other with lateritic soils modified with lime at a content of 8%. A self-designed model test system was used to conduct model tests of both embankments under combined action of wetting and vibration. White noise excitation was employed to quantitatively compare the two types of embankments in terms of variations of dynamic properties, such as natural frequency and damping ratio, with wetting degrees. Three types of seismic waves-Chi_Chi, NCALIF and SFERN-were used to quantitatively compare the two types of embankments in terms of variations of dynamic response parameters, including PGA amplification effect, pore water pressure and earth pressure, with wetting degrees and acceleration amplitudes. The test results reveal significant differences in dynamic properties and responses of the two types of embankments. Compared to the unmodified embankment, the damping ratio and PGA amplification factor of the modified embankment are reduced by up to 53.5% and 37.5%, respectively, resulting in an effective mitigation of the combined action of wetting and vibration. Test values of natural frequency, damping ratio, PGA amplification factor, dynamic pore water pressure and dynamic earth pressure of both types of embankments are presented. The research findings provide a theoretical basis for highway and railway construction and for revision of technical specifications in regions with widespread lateritic soils.

This study investigates the stress-strain relationship and damage evolution mechanism of alkali-activated coal gangue powder-based geopolymer solidified loess under uniaxial compression. Uniaxial compression tests were conducted on specimens with different mix proportions and curing ages, followed by the development of a damage constitutive model based on damage mechanics theory. The experimental results demonstrate that the compressive strength of the solidified loess increases with extended curing periods and higher binder content. By integrating Lemaitre's strain equivalence principle with a composite power function, a damage constitutive model was derived. The model exhibits strong consistency with experimental stress-strain curves, thereby validating its rationality and the accuracy of elastic coefficient determination. These findings provide critical insights into the damage evolution patterns during uniaxial compression failure of alkali-activated coal gangue powder-based geopolymer-modified loess. Furthermore, this study establishes a theoretical framework and offers practical references for characterizing damage constitutive relationships in geopolymer-stabilized soils.

Intensive agriculture development and achievement to higher profitability has inflicted permanent damage on agroecosystems. Rapid deterioration of structure and functional properties in agroecosystems has intensified the need for research on agroecosystem health and management. To assess the health status of wheat agroecosystems in the agricultural lands of Bandar-e-Turkmen county (Golestan province, Iran), we were used the variables of weed and natural enemies biodiversity, soil health (carbon and organic matter, microbial respiration, earthworm, soil salinity, and acidity), environmental indexes (environmental effects of pesticides (EIQ) and nitrate leaching) and vegetation indexes (RVI, cultivar type, and grain yield). In this study, thematic layers were prepared in ArcGIS and overlayed according to three scenarios. Then final layer was classified into three classes of health. Based on the results, only 8.47% (5 fields) were located in the first health class. These fields were characterized by high grain yield, low weed biodiversity, minimal pesticides use, optimal soil conditions, high RVI, and the presence of earthworms and natural enemies. Also, we found that 42 fields (71.19%) were placed in the second health class. Increase of biodiversity and population of weeds, lower grain yield, and reducing the quantity and quality of soil variables were important factors that reduced the health degree of these fields. Based on the results, 20.34% of the area (12 fields) in the central and western parts of the county was placed in the unhealthy class. It seems that increasing the environmental restrictions, including salinity higher than 6 ds/m, high weed diversity, increasing the consumption of harmful and dangerous pesticides with high environmental impact, and less grain yield than the potential of cultivars, were the main reasons for placing these fields in the unhealthy class. Also, the most important factors of decreasing the health degree of fields, frequency of weeds, increasing consumption of chemical pesticides, low soil organic matter, absence of earthworms, and decreasing grain yield were identified. Generally, management of weeds, implementation of crop rotation, preservation of plant residues on the soil surface, and development of conservation agriculture can help to improve the health indicators of wheat agroecosystems.

The Metro Jet System (MJS), widely utilized for reinforcing weak foundations, relies critically on the mechanical properties of its piles to ensure effective soil stabilization. Unlike laboratory-scale tests that often overlook real-world constraints and soil heterogeneity, this study conducted full-scale field experiments to replicate in-situ MJS pile formation. Core samples extracted post-construction were analyzed to evaluate the effects of cement content, radial non-uniformity, and surrounding soil characteristics on compressive strength, stress-strain behavior, and failure modes. Complementing the experiments, discrete element numerical simulations were employed to microscopically validate the mechanisms underlying macroscopic observations. The research findings indicate that the stress-strain relationship of the pile specimens exhibits strain-softening behavior, and post-peak brittleness of the specimens increases with higher cement content. The mechanical properties of the pile body specimens are significantly influenced by cement content and distance from the pile center, with less correlation to the strength of the surrounding strata. Higher cement content, shorter distance from the pile center, and increased strength are observed to be interrelated. Numerical simulation results show that as cement content increases, the rate of reduction in the coordination number of the specimens decreases. In the early stages of numerical experiments, the rate of increase in the number of cracks becomes progressively lower. A numerical model considering cement content for the mechanical properties of the piles was established, demonstrating good predictability for pile compressive strength. These results underscore the necessity of full-scale testing for reliable in-situ performance assessment and provide actionable insights for optimizing MJS pile design in geotechnical engineering.