Soil Structure Research Articles

Nonlinear 3D Finite Element Analysis of a Coupled Soil–Structure System by a Deterministic Approach

Fully coupled soil–structure analyses were performed for a building of strategic importance located in the city of Messina (Sicily, Italy). The structure was built after the destructive 1908 earthquake, also known as the ‘Messina and Reggio Calabria earthquake’, which caused severe ground shaking. A parametric study considering three seismograms of this earthquake was performed. Deep in situ and laboratory investigations allowed the definition of the geometric and geotechnical model of the subsoil. Numerical analyses were performed with PLAXIS3D finite element software (Version 21.01.00.479). The Hardening Soil model with small-strain stiffness was accurately calibrated using laboratory and field data. The dynamic response was investigated in terms of accelerations, response spectra, amplification functions, displacements and stress–strain hysteretic loops. The findings show that many aspects must be investigated for the retrofitting of buildings with shallow foundation in areas characterized by a medium to high level of seismic risk: (i) a key role is played by an accurate investigation of the soil; taking into account the specific conditions of the soil, it was possible to investigate its filtering effects; (ii) the dynamic response of the fully-coupled soil–structure system deviates from the free field-site response analysis; (iii) the results reveal the importance of considering the soil nonlinearity in seismic soil–structure interaction problems.

Investigation on structure, evaporation, and desiccation cracking of soil with straw biochar

AbstractTo investigate the cracking behavior in the evaporation process of the soil surface with biochar as an additive, five experimental groups were established in the natural environment with 0, 12, 60, 120, and 170 g·kg−1 biochar. The results of an investigation on organic matter and aggregations indicate that a high content of biochar can significantly improve the content of organic matter and the amount of soil aggregates. After adding 60 and 170 g·kg−1 biochar, the content of organic matter increased by 19.47% and 84.12%, respectively, and the content of soil aggregates with an average diameter greater than 0.25 mm increased by 16.43% and 38.20%, respectively. The investigation also examines the evaporation and cracking characteristics of soils that contain biochar. The rate of evaporation is approximately a “step” type function with time. The rate of evaporation is observed in three stages: the rapid, decelerating, and final evaporation stages. In the rapid evaporation stage, the initial evaporation rate of the sample that contains biochar is increased on average by 46%. The fractal dimension and cracks rate are decreased by 22.95% and 20.99% with 120 g·kg−1 biochar addition. This means that the increase of soil organic matter after adding biochar plays a crucial role in the stability of aggregates. As a soil conditioner, biochar has the ability to enhance soil water retention capacity and is a sustainable strategy to improve soil properties.

Comprehensive bioremediation effect of phosphorus-mineralized bacterium Enterobacter sp. PMB-5 on cadmium contaminated soil-crop system

Phosphate-mineralizing bacteria (PMBs) have been widely studied by inducing phosphate heavy metal precipitation, but current researches neglect to study their effects on soil-microbe-crop systems on cadmium (Cd) contaminated. Based on this, a strain PMB, Enterobacter sp. PMB-5, was inoculated into Cd contaminated pots to detect soil characteristics, Cd occurrence forms, soil biological activities, plant physiological and biochemical indicators. The results showed that the inoculation of strain PMB-5 significantly increased the available phosphorus content (85.97%−138.64%), Cd-residual fraction (11.04%−29.73%), soil enzyme activities (31.94%−304.63%), plant biomass (6.10%−59.81%), while decreased the state of Cd-HOAc (11.50%−31.17%) and plant bioconcentration factor (23.76%−44.24%). These findings indicated that strain PMB-5 could perform the function of phosphorus solubilization to realize the immobilization of Cd in the complex soil environment. Moreover, SEM-EDS, FTIR, XPS, and XRD analysis revealed that strain PMB-5 does not significantly alter the soil morphology, structure, elemental distribution, and chemical composition, which suggested that remediation of Cd contamination using strain PMB-5 would not further burden the soil. This research implies that PMB-5 could be a safe and effective bioinoculant for remediating Cd-contaminated soils, contributing to the sustainable management of soil health in contaminated environments.

Minor straw return enhances net income in a maize-wheat rotation system

Straw returning to the field is a common agricultural practice in China. Nevertheless, in the maize-wheat rotation system of the semi-arid region in Northwest China, it is essential to investigate the optimal approach for coupling straw return and fertilization in order to enhance soil quality and crop yield. A field trial conducted in the semi-arid region of northwest China from 2019 to 2021 examined eight different combinations of straw return and fertilization rates. The results indicated that while straw return had minimal impact on soil total nitrogen in the 0–60 cm layer, it did increase soil available phosphorus and potassium in the 0–40 cm layer. Additionally, all straw return treatments notably improved soil organic matter and humus content compared to the untreated control (CK). Specifically, applying N and P fertilizers in combination with returning 1/3 of the straw (NP+1/3S) produced in that season significantly boosted soil organic matter and humus content compared to the CK. Moreover, the NP+1/3S treatment led to a substantial enhancement in the grain yield of wheat and maize, as well as their yield components, including an increase in the number of ears/spikes per square meter, the number of grains per ear/spike, and the 100 or 1000-grain weight. The results may be attributed to a combination of factors, including improved nutrient availability, enhanced soil structure, and increased microbial activity due to the incorporation of straw. Economic analysis showed that NP+1/3S had the highest production to investment ratio (ROI), indicating its potential suitability for the region. This study highlights the significance of carefully selecting combinations of straw return and fertilization to maximize soil fertility, crop yield, and economic benefits in agricultural systems.

Role of Hazelnut Husk Compost and Phosphate Solubilizing Bacteria in Improving Productivity and Quality Parameters of Wheat (Triticum aestivum L.) and Their Effects on Some Soil Biological Properties

ABSTRACT Implementing compost can assist in improving soil structure and enable nutrient mobilization to plants that initiate an appropriate soil balance. In a greenhouse experiment, the influence of hazelnut husk compost (HHC), both in single and in combination with the phosphate solubilizing bacteria (PSB) on the wheat yield, yield parameters, and soil biological properties were investigated. A significant increase in yield and its quality parameters was recorded when the soil was treated with different doses of compost and bacteria. It was observed copious improvements in the soil biological properties with these applications. The microbial biomass carbon and total organic carbon ratios (Cmic:Corg) ranged from 1.51 to 2.09, were also remarkable in the organic amended soils. However, in all the treatments, the co-inoculation of bacteria with compost enhanced all the parameters significantly more than their individual applications. The highest yield increase over control (22.12%) was recorded from the integrated application of organic source and bio-fertilizer. This reflects a synergistic relationship between the compost and bacteria that eventually enhanced wheat production. It is therefore concluded that using HHC and PSB in soil can unfold promising possibilities for better soil health, which in the long run can contribute to sustainable food production.

Soil organic matter thermal pools as influenced by depth, tillage, and soil texture – A Rock-Eval® analysis study on the cropland soils of the Swiss Plateau

This study investigated the relationships between the soil organic matter content (SOM), SOM thermal pools, soil properties, and tillage practices, on cropland soils of the central plateau of Switzerland. Soil samples were collected in 45 no-till and conventional tillage fields in five layers from 0 to 40 cm depth. Soil organic carbon content (SOC) and hydrocarbon compound (HC) pools were analysed with Rock-Eval® thermal analysis. In addition, the clay content was determined by sedimentation.The SOM contents were highest in 0–5 cm of no-till soils and the plough pan of tilled soils. SOM was less oxygenated and showed lower degradation under conventional tillage then no-tillage. The proportion of the thermo-stable pool was mainly explained by the SOC:clay ratio, regardless of tillage practices. Below a SOC:clay ratio of 0.08, all pools were decreasing nearly equally with decreasing SOC. Above this ratio, thermo-stable pools increased only slightly, while thermo-labile pools increased linearly with SOC:clay on the full SOC:clay range. The 0.08 SOC:clay threshold in the thermo-stable pools content corresponded to the lower threshold of structure stability determined for Swiss and UK soils, below which, on average, severely degraded structures are observed in the field. These findings suggest that a large proportion of thermo-labile pool is necessary for acceptable to high soil structure quality, to protect the thermo-stable forms from degradation, and to reach the carbon sequestration potential of the soil.

Analytical solution for displacement-dependent active earth pressure considering the stiffness of cantilever retaining structure in cohesionless soil

The safety and cost-effectiveness of retaining structure designs depend on the interrelationships among the displacement, stiffness, and earth pressure. Nevertheless, the classical earth pressure theories do not account for these factors. To address this problem, the present study proposes an active earth pressure solution model that considers retaining structure stiffness and displacement. The model is based on the Modified Coulomb earth pressure theory and assumes a linear relationship between lateral earth pressure and displacement. The proposed model was compared with existing data, and degradation verification was performed. The verification results are in good agreement. According to existing calculation examples, a parameter analysis was conducted, and based on the analysis results, the critical points of rigidity and flexibility for cantilever-retaining structures of concrete materials were proposed. It was found that the resultant magnitude and point of application of the active earth pressure were related to the stiffness of the retaining structure. Further research was conducted on the variation patterns along the depth direction of the retaining structures with different stiffnesses under different displacement conditions. The computational model proposed in this study provides a practical approach for considering the coupled relationship between structural stiffness and active earth pressure in the design of retaining structures.

Soil macropores induced by plant root as a driver for vertical hydrological connectivity in Yellow River Delta

Abstract The protection and management of the wetland should consider the changes in hydrological connectivity caused by the structural modifications of the soil macropores. The main purpose of our work is to clarify and quantify the influence of the soil macropores volume on vertical soil hydrodynamic process mechanically and statistically by taking the form of a case-study in Yellow River Delta (YRD), and further reveal the vertical hydrological connectivity in this area. Based on X-ray computed tomography (CT) and constant head permeability test, the results showed a highly spatial heterogeneity of the soil structure in the YRD, hydraulic parameter (Ks) was negatively correlated with bulk density (BD) and positively with soil macropore volume, soil aeration (SA), and maximum water capacity (MWC). Using Hydrus 1-D software and the Green-Ampt model, we estimated the characteristics of hydrodynamic process in the soil without macropores, then evaluated the effect of the soil macropore on soil hydrological connectivity by comparing the experimental results with the simulation results. We found that increasing soil microporosity improved the convenience of water movement, which would enhance the hydrological connectivity of the region. The results will further help to reveal the eco-hydrological process at vertical scale in soil and provide a theoretical guide for wetland conservation and restoration.

Coupled hydro‐mechanical pore‐scale modeling of biopore‐coated clods for upscaling soil shrinkage and hydraulic properties

AbstractEarthworms and plant roots are vital for macropore formation and stabilization. The organo‐mineral coating of biopore surfaces also regulates macropore‐matrix mass exchange during preferential flow. The influence of finer‐textured burrow coatings on macroscopic soil properties during shrinkage could potentially be assessed by upscaling pore‐scale hydraulic and mechanical simulations. The aim was to investigate the influence of micro parameters (particle size, stiffness, and bond strength) on macro parameters (i.e., shrinkage curve and soil hydraulic properties). Drainage experiments and simulations were carried out using biopore‐coated clod‐size samples compared to those without coating. Simulations were performed using a two‐phase pore‐scale finite volume coupled with discrete element model (DEM‐2PFV). The structural dynamics was characterized by analyzing the pore volume and soil shrinkage curve obtained from numerically determined data. The soil hydraulic parameters were described using uni‐ and bimodal van Genuchten (vG) functions. The drainage simulations revealed hydro‐mechanical dynamics characterized by Braudeau‐shrinkage curve subdomains: The matrix‐only samples, with lower particle bond strength, exhibited relatively higher shrinkage. The coated samples, with higher particle stiffness and bond strength, displayed greater hydro‐mechanical stability. The numerically determined initial value of the saturated hydraulic conductivity (Ks) was about 70 times larger for matrix‐only samples than for coated samples. As expected, for the nonrigid soil structures, constant Ks, α, and n values for bimodal vG model resulted in prediction errors. Upscaling DEM‐2PFV pore‐scale model outcomes quantifies micro‐coating effects on macro hydro‐mechanics. This yields void ratio‐based soil water retention and hydraulic conductivity functions, advancing macroscopic soil hydraulic models and enhancing structured soil flow and transport descriptions.

The performance of partially substituted composite ester materials with weathered red-bed soil in ecological restoration.

Ester materials have become a significant topic in ecological restoration because of their degradability and lack of pollution. However, these artificial materials have issues such as high resource consumption and high cost. Therefore, finding a scientific substitute for ester materials is crucial to reduce costs. This study proposes the use of weathered red-bed soil to partially replace ester materials. Orthogonal coupled compounding and ecological effect tests were performed to analyze the soil improvement mechanism based on the mineral composition, soil structure, and electrical conductivity properties of the weathered red-bed soil. The experimental findings indicated that the soil modified using ester materials exhibited improved strength, water retention, and aeration owing to changes in the soil structure. Plant germination and height increased by 55% and 37 mm, respectively, when using a ratio of 15 g/m2 absorbent ester material, 2.5 g/m2 adhesive ester material, and 5% weathered red-bed soil. Through this approach, the amount of ester material to be used could be further reduced by 75%. The weathered red-bed soil offers improved ecological effects by altering the physical, mechanical, and hydraulic properties of the soil structure. This study presents a theoretical foundation for ecological conservation using weathered red-bed soil as a substitute for certain ester materials.

Soil structure and solute transport pathways in biogas digestate-amended soils

Here, we investigated the effects of biogas digestate application on flow pathways and soil properties in a sandy soil aiming at unraveling phosphorus accumulation and depletion processes in fertilized soils. Dye tracer experiments were conducted to visualize and distinguish between various flow pathways, while X-ray tomography was utilized to characterize the soil structure. The dye tracer experiments revealed differences between the control and the digestate-treated group of soil profiles in the top-soils although no statistical verification was possible amid a single plot per treatment. The stained soil profiles in both treatments indicate extensive areas of homogeneous and heterogeneous matrix flow. However, the digestate-treated group showed a decrease in homogeneous matrix flow and a notable presence of preferential flow with low interaction. The application of biogas digestate impacted various soil properties, including organic carbon content, water drop penetration time, and pH levels. Accordingly, the topsoil experienced an increase in soil organic carbon, water repellency, and a decrease in pH levels. The fraction of macropores also increased in the topsoil of the digestate-treated group, accompanied by an increase in tortuosity.Double lactate-extractable phosphorus (DL-P) distribution varied across the different flow pathways, with higher concentrations detected in matrix flow and a depletion observed in preferential flow regions in both treatments. These findings confirm the close relationship between the type of flow pathway and phosphorus distribution in soils. Additionally, a significant correlation was observed between pH levels and DL-P in the digestate-treated group, indicating potential implications for phosphorus availability. Overall, the results of this study suggest that the long-term application of biogas digestate is likely to improve soil properties as related to soil organic matter content, particularly in the topsoil of sandy soils. The study highlights the significance of the prevailing flow and transport pattern on nutrient distribution, with potential implications for nutrient management in agricultural systems. While the study design presented prevents the unequivocal assignment of differences to treatment effects, our data likely illustrate the impacts of biogas digestate amendment on the investigated sandy soil.Further research should focus on assessing the long-term effects of digestate application in loamy and clayey soils.

Differential response patterns of soil fungal and bacterial communities to typical vegetation types in the Yellow River floodplain ecosystem

Soil microorganisms are one of the primary driving factors of biogeochemical cycles in floodplain ecosystems. Vegetation type has an impact on the activities of soil microorganisms. However, it is currently unclear whether the composition and structure of soil bacterial and fungal communities in floodplain ecosystems have a consistent response pattern to vegetation communities. In this research, Illumina Mi-Seq sequencing technology was employed to study the soil fungal and bacterial communities covered by three typical vegetation communities in the Yellow River floodplain ecosystem. Our results showed that the underground biomass, total carbon (TC) and nitrogen (TN) were significantly different between the three vegetation communities. In the surface soil of summer, the Shannon index of fungi community was the highest in Tamarix chinensis (T. chinensis) and the lowest in Phragmites australis (P.australis). In autumn, the Shannon and Simpson indices of bacterial communities in surface soil were the highest in the P.australis and the lowest in the Sonchus arvensis (S.arvensis), but there was no significant difference in the β-diversity of bacterial community among the three vegetation communities. In autumn, the Chao1 index of fungal community in subsoil was the highest in P.australis and the lowest in S.arvensis, while there was no significant difference in the α-diversity of bacterial community among the three vegetation communities. In addition, there were considerable disparities in the fungal and bacteria community structure in various vegetation soils. Redundancy analysis (RDA analysis) showed that TN, TC, AP, pH, NO3 -, NH4 + and moisture content were key factors driving bacterial community structure, while TP, NH4 +, pH and moisture content were essential factors driving fungal community composition. These outcomes help to improve our understanding of the ecological model of soil fungal and bacterial community in floodplain ecosystems and give assistance in improving the role of an ecological barrier and floodplain service possibilities.

Influence of Shallow Foundations on the Response of Steel Wind Towers

The objective of this study, concerning the soil–structure interaction of shallow reinforced concrete foundations of wind towers with circular cross-sections, was determination in a closed form of the monotonic moment–rotation curve of the soil–foundation complex. This study was based on elastic and plastic analyses of shallow rigid foundations assuming a Winkler soil type including the flexibility of the foundation in the elastic range and the nature of the soil (cohesive and non-cohesive types) through corrective factors of the constant of the Winkler model. The flexibility of the foundations influences the moment–rotation response through the initial rotational stiffness with a coefficient between 1 and 0.7 for a width-to-span ratio between 5 and 2. The nature of the soil is considered through corrective factors of 0.75 and 1.3 of the Winkler constant for cohesive and non-cohesive soil, respectively. Analyses carried out stressed that a possible design valued to be adopted in a steel wind tower with shallow foundations is a diameter of the steel tube 1/15 of the height of the tower, a diameter of foundation 0.75 of the length, and a depth of foundation 1/10 of the diameter and thickness of steel tower ratio diameter equal to 1/10. In this range it was observed that the effects of the soil-to-foundation interaction in the elastic range influences the critical length in the stability of the steel wind tower, with values between 2.5 and 2 (column fixed at the base) in a range of Winkler constant between 0.1 and 1 daN/cm3. Finally, an experimental validation of the proposed model was carried out with the data available from the literature.

Assessment of the impact of the degrees of degradation of pastures on the desert alluvial meadow soils of the village of Zhambyl

The article considers the features of the structure, chemical composition and physical properties of alluvial meadow soils of the pastures of the desert zone of the village of Zhambyl. These soils were formed in the sandy and sandy alluvial deposits of the Shu River. The soils of the floodplain of the river are mainly characterized by high fertility potential. But one of the factors limiting the growth of their potential fertility is the salinity of the soil image and the degree of degradation of pastures. The assessment of soil and plant indicators of pasture degradation in the Zhambyl base area is given. Previously, the area was irrigated and fertilized, and now it is used as a pasture. But due to overgrazing, the alluvial meadow soils of the desert near the village of Zhambyl and the vegetation on their surface have undergone anthropogenic degradation. Studies have shown that as the degradation of pastures increases, the thickness of the humus layer (A+B1) thinns, and the content of humus and nutrients in the soil decreases. The species and botanical composition of plants is undergoing changes, reducing their protection of the soil surface and the productivity of pasture feed. The results obtained are the theoretical foundations for the development of measures to increase soil fertility and productivity of natural vegetation on degraded pastures in the desert zone.

The organic carbon‐to‐clay ratio as an indicator of soil structure vulnerability, a metric focused on the condition of soil structure

AbstractThe soil organic carbon to clay ratio (SOC:clay) is a metric used in soil quality management. In Switzerland and the United Kingdom, for example, threshold values for SOC:clay ratios have been determined to indicate very good (>1:8) to degraded (<1:13) soil structures. A recent article in Soil Use and Management by Poeplau and Don, however, suggested that this metric is ‘strongly biased and misleading’, based on their observation that German sandy soils and heavy clay soils tend to show very high and very low SOC:clay ratios, respectively. An alternative metric was proposed based on the ratio of actual SOC to expected SOC level for a considered area. We offer a commentary on the proposal, arguing that because soil structure quality is overlooked by the approach, it fails to provide appropriate SOC levels for soil health and could lead to soils with highly depleted SOC being classified ‘good’. The SOC:clay ratio, on the other hand, does address soil structure condition, providing a structure vulnerability index, a key function independent of local soil management conditions. When soils are found to have high structure vulnerability, as indicated by the SOC:clay ratio, the cropping practices at the site should be investigated and ways to increase the SOC content considered. Structure condition threshold values may only need to be reassessed if it is shown that the average structure quality observed is not in conformity with the present thresholds, which would be expected for some soils, such as Andosols.

Comparing structural soil properties of boreal clay fields under contrasting soil management

AbstractSoil management significantly affects soil structure. Tillage and grassland renovation may have destructive influences, while conversion of arable land to grassland can improve pore structure and related soil functions. In crop rotations including perennial grasses, soil structure is affected by these counteracting processes. This work aimed to quantify the impacts of different soil management practices on the structure of boreal clay soils. We studied intact topsoil samples taken from two locations by X‐ray computed microtomography, image‐based flow simulations and water retention measurements. At both locations, adjacent field areas with two contrasting soil management histories were compared. Both locations had at least a 30‐year‐old grassland site, which was compared to arable soils either under no‐till management with annual crop rotation or conventional tillage with crop rotation including perennial grasses. Both imaging and water retention measurements showed significant differences in the soil macropore structure between the long‐term grassland and arable no‐till soil such that macroporosity and hydraulic conductivity of the long‐term grassland were higher than those of soil under agricultural production. On the contrary, at the second study location, differences between long‐term grassland and cultivated fields were minor and the long‐term grassland exhibited lower macroporosity. Our results confirm that soil management affects the macropore structure of boreal clay soil and that no‐till annual cropping and periodically tilled crop rotation including perennial phases exert different effects on the soil structure as compared with long‐term grassland.

Linking the humification of organic amendments with size aggregate distribution: Insights into molecular composition using FT-ICR-MS

Soil organic matter (SOM) plays a pivotal role in enhancing physical and biological characteristics of soil. Humic substances constitute a substantial proportion of SOM and their increase can improve crop yields and promote agricultural sustainability. While previous research has primarily assessed the influence that humic acids (HAs) derived from natural water have on soil structure, our study focuses on the impact of HAs on soil aggregation under different fertilizer regimes. During the summer cropping season, maize was cultivated under organic and synthetic fertilizer treatments. The organic fertilizer treatment utilized barley (Hordeum vulgare L.) and hairy vetch (Vicia villosa R.) as an organic amendment five days prior to maize planting. The synthetic treatment included a synthetic fertilizer (NPK) applied at South Korea's recommended rates. The organic treatment resulted in significant improvements in the soil aggregates and stability (mean weight diameter, MWD; p < 0.05) compared to the synthetic fertilizer application. These improvements could be primarily attributed to the increased quantity and quality of HAs in the soil derived from the organic amendment. The amount of extracted HAs in the organic treatment was nearly twice that of the synthetic treatment. Additionally, the organic treatment had a 140 % larger MWD and a 40 % increase in total phenolic content compared to the synthetic treatment. The organic treatment also had an increased macronutrient uptake (p < 0.001), an 11 % increase in aboveground maize biomass, and a 21 % increase in grain yield relative to the synthetic treatment. Thus, the enhancement of HA properties through the incorporation of fresh organic manure can both directly and indirectly increase crop productivity.

The effect of tire inflation pressure and tillage systems on soil properties, growth and yield of maize and soybean in a silty clay loam soil

AbstractSoil compaction causes adverse effects on soil structure and the performance of crops. There is significant literature supporting the hypothesis that reducing tire inflation pressure can help to minimize compaction, but there is no data on the potential benefits of high flexion tires operating at reduced tire pressures in Midwestern United States agriculture. Hence, a field‐scale study was established in Illinois to determine the potential benefits of high flexion tires at low tire pressure (LTP) in comparison with those operated at standard tire inflation pressure (STP) on soil condition, crop growth and yield of maize and soybean for three tillage systems; deep tillage (450 mm), shallow tillage (100 mm) and no‐till. Two adjacent experiments were established in typical maize/soybean and soybean/maize rotations, respectively. The experiment used a 2 × 3 factorial design with five completely randomized blocks. The results showed that the use of LTP tires resulted in lower soil penetrometer resistance for three tillage systems in 2017 and 2018 in the maize field and 2018 in the soybean field. This improved plant establishment and the number of plants per hectare of maize in both 2016 (*p ≤ .05) and 2018 (**p ≤ .01) and plant establishment (***p ≤ .001) and the number of plants per hectare (***p ≤ .001) of soybean in 2018. The penetrometer resistance was higher in the no‐till plots compared to deep and shallow tillage plots in maize and was higher in the deep tillage plots compared to the shallow tillage in the soybean field. The use of LTP tires resulted in an increased grain yield of maize by 4.31% (15.02 Mg ha−1) and 2.70% (14.76 Mg ha−1) in 2017 (**p ≤ .01) and 2018 (*p ≤ .05), respectively, and soybean by 3.70% (4.25 Mg ha−1) in 2018 (*p ≤ .05). The depth of tillage had a significant effect on soybean and maize yields in 2017 (***p ≤ .001) and 2018 (***p ≤ .001), respectively, with higher yields of both soybean and maize in the deep and shallow tillage compared to no‐till plots. The study concludes that the use of the LTP systems can be a potential means of addressing soil compaction and maintaining soil porosity while increasing crop productivity in silty clay loam soils in Central Illinois.

Short‐term effects of double‐layer ploughing reduced tillage on soil structure and crop yield

AbstractSoil tillage is widely acknowledged to affect soil characteristics and agricultural productivity. This research investigates the short‐term effects of various tillage methods on soil physical properties and crop yields at a Central German field site with a dry climate (mean temperature 9.5°C; annual precipitation 470 mm). Three tillage approaches were evaluated: conventional plough tillage (25 cm depth), cultivator tillage (18 cm depth), and double‐layer plough tillage (15 and 30 cm depth). We assessed soil physical properties through standard laboratory analyses, compression tests, soil pore structure via X‐ray computed tomography (X‐ray CT) and crop yields over 3 years. The results indicate that cultivator tillage approach increased soil bulk density relative to conventional tillage, especially in the second year, though this effect diminished over time. Double‐layer plough tillage emerged as a viable short‐term alternative to conventional tillage, achieving comparable soil bulk density. Saturated hydraulic conductivity values were generally higher for soils under conventional tillage or double‐layer plough tillage than for cultivator tillage, highlighting their soil loosening effect. Classical soil analysis methods combined with X‐ray computed tomography provided valuable insights into tillage induced changes to soil structure. Cultivator tillage resulted in a distinct pore structure with reduced macroporosity and pore connectivity. Despite notable soil property variations, crop yields remained consistent across the tillage methods. Overall, double‐layer plough tillage presents a sustainable option, moderately improving soil physical properties while maintaining crop yields. This study highlights the need to assess the short‐term effects of tillage on soils and contributes to the broader dialogue on optimizing tillage strategies for effective soil management and crop production.

Hydraulic Conductivity of Soils: A Comprehensive Review of the Impacts of Chemicals, Soil Salinity, Organic Matter, and Land Use

The contamination of groundwater by toxic heavy metals, organic compounds, and microbiological contaminants is a significant issue worldwide. To address this problem, various methods have been employed, including in-situ remediation and transporting polluted soil or groundwater for final treatment. This study aims to review the impact of soil heterogeneity on in-situ remediation, with a particular focus on subsurface preferential flow that accelerates solute transport. The study highlights the importance of soil hydraulic conductivity in soil production, ecological health, and water resource management. Soil hydraulic conductivity is influenced by soil structure, moisture content, and chemical exposure. The findings of this study emphasize that sustainable soil management and environmental restoration require an understanding of hydraulic conductivity parameters and the implementation of appropriate management strategies.