High Clay Research Articles

Modeling Cork Yield, Thickness, Price, and Gross Income in the Portuguese Cork Oak Montado

The cork oak (Quercus suber L.) woodlands, known as montados in Portugal, hold significant economic, cultural, social, and environmental value. They are found in the Mediterranean Sea basin, particularly in the Iberian Peninsula, and sustain various activities like silvopastoralism, with cork being a primary product. Despite its economic significance, challenges such as climate change threaten its sustainability. This study aimed to analyze the edaphoclimatic variables affecting cork yield, thickness, price, and gross income in the Alentejo region of Portugal. A total of 35 farmers were selected for the data collection included in this study. Multivariable linear regressions were performed to establish relationships between cork yield, thickness, price, and gross income as dependent variables, various edaphoclimatic factors, and tree densities. A higher tree density correlates with an increased cork yield but a decreased cork thickness. Soil pH affects cork yield and thickness, with a lower pH favoring higher cork yields but thinner cork. A higher clay and silt content in horizon soil C enhances cork thickness and raises the price but reduces the cork yield. Higher accumulated precipitation and temperatures contribute to higher yields and thicknesses of cork. It is concluded that the relationships between the dependent and the independent variables are complex but partially explainable. Understanding these relationships is paramount to ensure sustainable management practices are adopted that are capable of addressing issues raised in the current context of climate change.

The effectiveness of fly ash and fly ash-cement mixtures as stabilizing materials for high plasticity clay

Abstract The increasing activity of burning coal as fuel for Steam Power Plants (PLTU) will increase the amount of fly ash waste, urging the industry to maximize waste utilizations as, for instance, a stabilizing material for high plasticity clay. This research examined the effectiveness of clay + fly ash and clay + fly ash + cement stabilization in increasing the strength of road subgrade. The results showed that fly ash and fly ash + cement improved clay properties, demonstrated by the value of unsoaked CBR (5.78%) and soaked CBR (3.11%) of unstabilized clay. Clay + 20% fly ash yielded optimum CBR value (23,13%), and stabilizing clay subgrade on a 50-meter section using 20% fly ash at a cost of IDR 18,329,675. The mix of 40% fly ash + 15% cement yielded optimal CBR value (42.70%) at a cost of IDR 18,359,435.00. The evaluation of soil properties and cost analysis, shows that the most efficient mixture variation is 40% fly ash and 15% cement for clay stabilization.

Characterising geomaterial shakedown and related deformation accumulation from cyclic triaxial tests

Permanent deformation accumulation in soils and unbound granular materials under repetitive loading leads to surface rutting in roads and deterioration of track geometry in railways, eventually requiring costly and disruptive maintenance. Cyclic or repeated load triaxial tests are a convenient test method to characterise the permanent deformation behaviour of different soils under high numbers of load repetitions and a large volume of data is available. Existing empirical functions either take no account of shakedown, leading to an over-prediction of deformations at a high number of load cycles, or those that do take account of shakedown contain a high number of regression parameters that make them difficult to use. A simple empirical function with only one input parameter is proposed to characterise the accumulation of permanent axial strain in cyclic triaxial tests on a wide range of geomaterials undergoing shakedown deformations. It is shown to give predictions of a similar accuracy to existing functions at low numbers of load cycles and increased accuracy at high numbers of load cycles. It is shown to be applicable to soils ranging from a high plasticity clay to a rail ballast, across a range of stress states, stress history and strain levels provided that ratcheting deformations do not occur. The single input parameter has a physical meaning and is related to the permanent deformation required to reach the shakedown condition. Since the proposed function predicts the slowing rate of deformation accumulation towards shakedown not covered by the commonly-used existing functions, it could lead to more economical designs of applications involving high numbers of load repetitions. Its broad application to both coarse granular materials and fine-grained soils should streamline the design of applications involving layers of both these material types without the need to change empirical function.

Behavior of CBR value of laterite soil mixed with metakaolin

Laterite soil is a material widely used for civil engineering purposes in South Kalimantan. Most laterite soil has low bearing capacity due to high clay and plastic content, causing cracks and damage, especially when mixed with a fairly high volume of water. Therefore, this study aimed to improve the soil through stabilization using metakaolin. An experimental study was conducted using laterite soil from Mount Kupang, Cempaka Village, Banjarbaru. This soil wasmixed with metakaolin on various percentage variations of the mixture, namely 2%, 4%, 6%, 8%, and 10% of the weight. The incubation period of the sample commences from 3, 7, and 14 days. Some of the test conducted include soil consistency limits (Atterberg limit test), soaked laboratory, and unconfined compressive strength (UCT). The result showed an effect on the characteristics of laterite soil mixed with metakaolin. The Plasticity Index (PI) value of laterite soil experienced a constant decrease due to the influence of methakoline by 14.75%. The soaked CBR value increased in a mixture of 2 to 8% metakaolin, but there was a decrease in the case of 10% at a curing time of 3, 7, and 14 days. Furthermore, the maximum soaked CBR value in laterite soil samples was mixed with 10% metakaolin at a curing period of 14 days and experience a percentage increase of 43.47%. The maximum qu value also increased by 42.02% in a mixture of 8% metakaolin and decreased in a 10% metakaolin at a curing time of 14 days.

A Correlation Relating the Residual Strength Parameters to the Proportions of Clay Fractions and Plasticity Characteristics of Overburden Sediments from the Open-Pit Mine Drmno

One of the prerequisites for the safe exploitation of surface mines is the stability of the working and final slopes of the mine. In order to ensure this, it is necessary to carry out detailed field and laboratory geomechanical tests of the soil and, based on the obtained results, make calculations related to stability analyses. The results obtained in this way are used for dimensioning the slope of exploitation slopes (excavation). Landslides occur when the ultimate shear strength is reached, and therefore, the adequate definition of shear strength parameters is one of the essential prerequisites for successfully solving the stability problem. Unlike earlier tests in Serbia, when the residual shear strength parameters were determined based on the usual conventional methods (direct shear apparatus, triaxial apparatus), this time, in addition to the direct shear apparatus, a ring shear apparatus was also chosen for testing. The paper shows the method of determining the residual shear strength parameters of high plasticity gray clays and siltstones of roof sediments from open pit mine Drmno, using direct and ring shear apparatus. The results show that the residual angle of internal friction for gray clays obtained with the ring shear apparatus is 9.9–10.8°, and for the siltstone, it is 11.8–12.9°, both of which are lower than the values obtained with the direct shear apparatus. In addition, correlations between the residual parameters of soil shear resistance and some physical indicators (plasticity index, clay content) are provided, showing high correlation coefficients. The proposed correlations should be used only when time and financial constraints prevent the execution of actual tests to determine residual shear strength, as concrete experimental procedures provide a much more reliable assessment of the residual strength properties of the soil.

Investigation of the pore structure characteristics and fluid components of Quaternary mudstone biogas reservoirs: a case study of the Qaidam Basin in China

Quaternary mudstone biogas reservoirs in the Qaidam Basin have shown great potential. However, complex pore structures with high clay contents and high heterogeneity limit the understanding of the storage and migration principles of these reservoirs. In this paper, HPMI and nitrogen adsorption experiments, in combination with NMR experiments under water saturation, centrifugation, various drying temperatures and other conditions, were adopted to determine the pore structure characteristics. Specifically, the reservoir space types and pore radius distribution characteristics were clarified. The cutoff values for different types of pores were identified based on the water-saturated mudstone NMR T2 spectra for full aperture distribution scales jointly characterized by mercury injection and nitrogen adsorption experiments. Furthermore, the three pore components and the saturation of different fluids were obtained. The research results indicate that the mudstone biogas reservoir has developed various reservoir spaces, and the pore size is primarily in the micronanometer range. The average total porosity reaches 27.28%, but the proportion of movable water pores is only 9.23% with poor fluid mobility, and the fluids in the pores are mostly capillary-bound water and clay-bound water. Among the different lithologies, argillaceous sand is more likely to become a good production layer.

Study on combination of surfactant and acid for depressure and increasing injection oil displacement in heterogeneous sandstone reservoirs

This study addresses the challenges faced by unconventional tight sandstone reservoirs, including low porosity, permeability, high clay content, and complex wettability, which lead to increased flow resistance and injection pressures. The research aims to optimize depressure and increasing injection methods by investigating the effects of various two-phase and three-phase displacement systems, employing experimental treatments including acids, alkalis, and surfactants. Nuclear magnetic resonance, computed tomography, scanning electron microscopy, inductively coupled plasma, and wettability tests are utilized to investigate the mechanisms of these treatments. Key findings indicate that weak alkaline ethylenediaminetetraacetate tetrasodium and weak acids like hydroxyethylidene diphosphonic acid and acetic acid can cause significant pore blockage, while hydrochloric acid can dissolve pore minerals, achieves a high depressure rate of 89.42%. Although surfactants exhibit a negative effect in two-phase displacement systems, they demonstrate considerable potential in three-phase displacement. Surfactants can modify the wettability of rock surfaces, reduce oil saturation, and improve water phase permeability, resulting in a depressure rate of 11.68%. Notably, the combination of surfactants and HCl enhances the depressure rate to 60.82% and improves oil displacement efficiency from 26.12% to 57.96%. The optimal formulation identified is “0.5% unconventional agent (CNI-A) +3% HCl,” which improves oil displacement capacity and alleviates injection pressure, providing valuable insights for the management of heterogeneous sandstone reservoirs.

An Experimental Study on the Compressibility of Clays Reinforced with Basalt Fiber

The use of basalt fiber has become quite common in soil reinforcement works, which emerged as an alternative to traditional soil improvement methods and are carried out using different types of fibers. Basalt fiber, whose raw material is basalt rock, is preferred in soil reinforcement works due to its features such as high strength, economical, environmentally friendly, natural and abundant. In this study, the effects of basalt fiber reinforcement on the compressibility of high plasticity bentonite clay were examined. Bentonite clay was reinforced with 24 mm long basalt fiber at different rates between 0.5% and 5.0%, and standard proctor tests were carried out on these mixtures. With experimental studies, maximum dry density (γdmax) and optimum water content (Ꞷopt) values were determined and the effects of basalt fiber reinforcement on these parameters were evaluated. According to the test results, while γdmax values increased up to 2.5% basalt fiber reinforcement ratio, Ꞷopt values decreased. In samples with basalt fiber ratio greater than 2.5%, γdmax values decreased and Ꞷopt values increased. The results obtained showed that the basalt fiber ratio at which bentonite can be compressed best is 2.5%, and basalt fiber reinforcement at rates greater than this ratio negatively affects the compressibility.

Particle size characteristics of sliding-zone soil and its role in landslide occurrence: a case study of the Lanniqing landslide in Southwest China

In landslide studies, particle size is a key quantitative indicator, reflecting the formation and development of the sliding zone. It plays a crucial role in understanding the mechanisms and evolutionary processes that lead to landslide occurrences. Precise measurement of particle size is crucial. This study centered on soil samples from the Lanniqing landslide in Southwest China. To begin, seven distinct methods were used to preprocess the soil samples. Next, the particle size frequency distribution was measured using the Mastersizer 2000 laser particle size analyzer. Key parameters, including median particle size, mean particle size, sorting coefficient, skewness, and kurtosis, were then compared and analyzed to determine the most appropriate preprocessing method for evaluating the characteristics of the soil samples. The mechanism of landslide occurrence was subsequently analyzed by examining the particle size characteristics, mechanical properties, and mineral composition of the soil samples. The results suggested that method C provides the most reliable analysis of particle size characteristics in soil samples. The observed coarsening of coarse particles, along with a significant increase in clay content within the sliding zone, indicates that the sliding surface has undergone multiple shear and compression events. The interplay of the upper traffic load and slope cutting at the front edge set the stage for the Lanniqing landslide, prompting the initial development of potential sliding surfaces. Rainfall acts as a catalyst for slope instability. The high clay content, combined with the formation of a low-permeability layer rich in clay minerals on the sliding surface, leads to excessive pore water pressure and mineral lubrication. These factors inherently trigger and accelerate the occurrence of the landslide.

Effect of Chloride Solution on Liquid Limit, and Plasticity Index of Soil in Selected Sites in Erbil /North Iraq

This study is an attempt to investigate the effect of NaCl, CaCl2, KCl, and NH4Cl solutions with different concentrations (2.5%, 5%, 7.5%) on the liquid limit, plastic limit, and plasticity index of Sarbasty and Mamwastayan soil samples /Erbil Governorate. The soil samples' liquid and plastic limits were found by using the cone penetrometer method. The Results showed that the soil's liquid, plastic limits, and Plasticity index decreased with increasing salt solution concentration. Maximum reduction of liquid limit and plastic limit in Sarbasty was from 53.6 to 34.3 and in Mamwastayan from 35.9 to 27.2, both accomplished by adding a concentration of 7.5% of KCl and CaCl2 respectively. According to the Unified Soil Classification System, the Sarbasty soils were classified as high plasticity clay (CH), and Mamwastayan low plasticity clay (CL). After adding different concentrations of salt solution to the soil, the Sarbasty soil classification changed from CH to CL. Mineralogically these soils are composed of non-clay minerals of calcite and quartz and clay minerals consisting of Montmorillonite, Chlorite, swelling Chlorite, Kaolinite, Illite, Palygorskite, and Illite- Chlorite. Sarbasty soil was the most effective salt chloride solution than the Mamwastayan soil sample swelling.

Exploring soil pedogenesis through frequency-dependent magnetic susceptibility in varied lithological environments

AbstractThe use of percent frequency-dependent magnetic susceptibility (χfd%) is well-established for detecting superparamagnetic (SP) components in fine-grained soils and sediments. This study employs χfd% as a direct indicator of pedogenetic processes in soils from the Moroccan Rif region. Three soil transects (T1, T2, and T3), each comprising four soil cores with depths reaching 100 to 120 cm, were sampled from distinct lithological formations within an area subject to moderate to intense erosion. A total of 272 soil samples were collected and analyzed using MS2 Bartington Instruments, providing values to calculate χfd% and identify ultrafine ferrimagnetic minerals (SP, < 0.03 μm). In Quaternary fluvial terraces (T1) soils, approximately 60% of the samples indicate a mixture of SP, multidomain (MD), and Single Stable Domain (SSD) magnetic grains, while 30% contained coarser MD grains. Only 10% of the samples exhibit predominantly superparamagnetic (SP) grains. Soils on marly substrates (T2) showed 90% of samples with a combination of SP, MD, and SSD, and just 10% had SP grains. In contrast, soils from Villafranchian sandy deposits displayed χfd% values exceeding 10% in over 50% of samples, indicating that almost all iron components consist of SP grains. Physico-chemical analyses of the soils in profiles T1, T2, and T3 reveal distinct characteristics, including variations in clay content, organic matter, nutrient levels, and proportions of free and total iron. These results are important for understanding soil evolution and pedogenesis, with profiles T1 and T3 showing advanced development marked by high mineral iron, clay, and organic matter content. In contrast, profile T2 reflects a weak stage, influencing nutrient availability and contributing to overall soil dynamics in the respective profiles. The results of this study suggest that magnetic susceptibilities in these samples primarily originate from pedogenetic sources, revealing significantly advanced pedogenesis compared to T1 and T2 soils. The findings of this study align with previous research on soil erosion and degradation in the region, demonstrating that soils developed on terraces and marly substrates are more degraded and less stable than those on sandy substrates. This study underscores the utility of magnetic susceptibility as a rapid and effective indicator for initial soil assessment and gauging the degree of pedogenesis.

Geological and Engineering Integration Fracturing Design and Optimization Study of Liushagang Formation in Weixinan Sag

The Weixinan Sag in the Beibuwan Basin is rich in shale oil resources. However, the reservoirs exhibit rapid phase changes, strong compartmentalization, thin individual layers, and high-frequency vertical variations in the thin interbedded sandstone and mudstone. These factors can restrict the height of hydraulic fracture propagation. Additionally, the low-porosity and low-permeability shale oil reservoirs face challenges such as low production rates and rapid decline. To address these issues, the Plannar3D full 3D fracturing model was used to simulate hydraulic fracture propagation and to study the main controlling factors for fracture propagation in the second member of the Liushagang Formation. Based on the concept of geological–engineering integration, a sweet spot evaluation was conducted to identify reservoirs with relatively better brittleness, reservoir properties, and oil content as the fracturing targets for horizontal wells. The UFM model was then applied to optimize fracturing parameters. This study indicates that the matrix-type oil shale has a high clay mineral content, resulting in a low Young’s modulus and poor brittleness. This makes hydraulic fracture propagation difficult and leads to less effective reservoir stimulation. In contrast, hydraulic fractures propagate more easily in high-brittleness interlayer-type oil shale. Therefore, it is recommended to prioritize the extraction of shale oil from interlayer-type oil shale reservoirs. The difference in interlayer stress is identified as the primary controlling factor for cross-layer fracture propagation in the study area. Based on the concept of geological–engineering integration, a sweet spot evaluation standard was established for the second member of the Liushagang Formation, considering both reservoir quality and engineering quality. Four sweet spot zones of interlayer-type oil shale reservoirs were identified according to this evaluation standard. To achieve uniform fracture initiation, a differentiated segment and cluster design was implemented for certain high-angle sections of well WZ11-6-5d. Interlayer-type oil shale was selected as the fracturing target, and the UFM was used for hydraulic fracture propagation simulation. Fracturing parameters were optimized with a focus on hydraulic fracture characteristics and the estimated ultimate recovery (EUR). The optimization results were as follows: a single-stage length of 50 m, cluster spacing of 15 m, pump injection rate of 10 m3/min, fluid intensity of 25 m3/m, and proppant intensity of 3.5 t/m. The application of these optimized fracturing parameters in field operations resulted in successful fracturing and the achievement of industrial oil flow.

The impact of pore heterogeneity on pore connectivity and the controlling factors utilizing spontaneous imbibition combined with multifractal dimensions: Insight from the Longmaxi Formation in Northern Guizhou

The heterogeneity of shale pores, a crucial factor in the occurrence and migration of shale gas, exerts a significant impact on the pore connectivity. Pores exhibiting a range of structural attributes to the complexity of pore connectivity. A comprehensive study into the impact of pore heterogeneity on pore connectivity in shale is lacking. This study aims to explore the impact of pore heterogeneity on pore connectivity in shale and the primary controlling factors of pore connectivity. Shale pore connectivity, pore structures, mineral composition, and geochemical parameters were assessed using various tests, including spontaneous imbibition, adsorption, mercury intrusion capillary pressure (MICP), focus ion beam-scanning electron microscopy (FIB-SEM), sulfur and carbon analysis, vitrinite reflectivity, and X-ray diffraction (XRD). Pore heterogeneity was quantitatively analyzed using the multifractal dimensions method. Results show that the increased heterogeneity of pore structure and surface roughness facilitating the potential for increased connectivity. The presence of well-developed micro-mesopores within the organic matter, alongside numerous disconnected and independent pores, contributes to an increase in pore heterogeneity. Micro-mesopore structures have a more pronounced impact on pore heterogeneity than macropores. The heterogeneity of the pores is predominantly influenced by variations in the PV and SSA of micro-mesopores. Furthermore, the heightened heterogeneity of pore structure (D1) and surface roughness (D2) leads to a more complex pore structure with increased roughness, promoting the potential for enhanced connectivity through additional throats and facilitating the formation of secondary microfractures. Shale cores characterized by high total organic carbon (TOC) content, porosity, and clay mineral content are conducive to improved pore connectivity. Conversely, the increase of thermal evolution maturity of shale in the over-mature stage is not conducive to the increase of pore connectivity. Thermal evolution maturity, TOC content, and clay mineral are key factors that control pore heterogeneity, further affecting the connectivity of shale pores. High pore connectivity is conducive to spontaneous imbibition capacity and the formation of hydraulic microfractures, promoting the migration of shale gas.

Research and Practice of Sand Control Completion Technology Optimization in Western H Oilfield

Abstract In view of the problems of poor reservoir physical properties, high clay content, loose cementation, shallow burial, low compaction degree, low temperature in the middle and deep oil layers during the development process of unconsolidated sandstone reservoirs in the western H oilfield, the original sand control technology has poor adaptability and short sand control validity period., this paper carried out research on the optimization of sand control completion technology. In the study, a series of optimization studies were conducted, including analysis of acoustic time difference in sand producing layers, simulation of sand control formation compaction, optimization of gravel filling particle size, and sand control tools. A high-strength artificial wellbore and cyclic gravel filling sand control completion process suitable for different sand producing well conditions were developed and applied in practice. The research results and on-site practice indicate that the high-strength artificial wellbore sand control completion technology has good adaptability in low-temperature and long wellbore sand production wells; The cyclic gravel filling sand control completion technology has the advantages of simple construction, low cost, and low probability of major repairs in conventional shallow sand producing wells; The complementary advantages of the two processes effectively solve the problem of sand damage in H oilfield. Since 2021, the optimized sand control completion technology has been applied 46 times in H oilfield, with an average recovery oil production of 3.4t per well and an average effective period of over 500 days for sand control. The overall input-output ratio is 1:2.8, achieving good benefits and having high promotion and application value.

Modified Low-Field NMR Method for Improved Pore Space Analysis in Tight Fe-Bearing Siliciclastic and Extrusive Rocks

Abstract Understanding the filtration and storage properties of tight reservoirs is crucial for efficient resource exploitation, particularly in unconventional formations. This study presents two low-field nuclear magnetic resonance (LF-NMR) techniques: standard cut-off and modified differential approaches combined with mercury injection capillary pressure (MICP) and X-ray diffraction (XRD) studies to evaluate porosity and pore size distribution (PSD) in such formations. The differential technique involves subtracting the dry sample signal from a 100% water-saturated one, allowing the chemically bound water compound to be eliminated and facilitating PSD analysis. Through the application of the percolation theory, we established a power–law relationship between LF-NMR transverse relaxation time (T2) and MICP pore-throat diameter, enabling the derivation of PSD and pseudo capillary pressure curves. Our methodology was validated on a sample set representing tight sandstones, conglomerates, and extrusive rocks with high clay and iron mineral content, demonstrating the superior accuracy of the modified differential method in estimating effective porosity and absolute PSD in comparison with the standard approach. While the use of the percolation theory in PSD conversion was successful for rocks with unimodal distributions, it often failed for rocks with larger voids. The study also revealed that the relationship between the LF-NMR transverse relaxation times and MICP pore sizes is both nonlinear and challenging to describe with a universal equation, especially in the presence of para- and ferro-magnetic elements in the rock matrix. Despite obstacles to the complete elimination of the influence of these minerals on the T2 distribution, employing the modified differential LF-NMR method significantly mitigated this effect and offered a precise and noninvasive way of characterizing the petrophysical properties of tight reservoir rocks. Consequently, our studies offer a significant step toward a more precise assessment of pore structures in unconventional reservoirs that could be translated into more efficient strategies for locating geothermal heat and hydrocarbon resources.

Integrated geological quality evaluation using advanced wireline logs and core data: a case study on high clay shale oil reservoir in China

Abstract In the unconventional energy sector, shale oil is increasingly recognized as a crucial supplement to production. In recent years, China has made significant advancements in the development of shale oil. A unique type of pure shale reservoir in the Songliao Basin, distinct from established shale oil reservoirs worldwide, has emerged as a focal point for exploration and research endeavors. This kind of shale exhibits enhanced heterogeneity, high clay content, intricate rock electricity relationship, posing significant challenges to formation evaluation. This study introduces conversion coefficients for the elements and minerals, a decision tree model, a variable T2 cutoff value method, and 2D NMR cluster analysis, all based on the integration of microimaging, spectroscopy, and 2D NMR logging. These novel approaches facilitate a comprehensive geological quality evaluation of key parameters, including mineral composition, lithology, effective porosity, total organic carbon content, fluid composition, and saturation characteristics within pure shale formations from the Songliao Basin. The established petrophysical model has been validated by core analysis data and successfully applied in exploration wells. Through systematic petrophysical analysis, the optimal landing point for horizontal wells was identified based on the identification of the best reservoir quality interval with high movable oil and oil saturation. The subsequent drilling of horizontal wells demonstrated the reliability of petrophysical evaluation in terms of oil production. This integrated evaluation method for pure shale holds reference significance for similar shale reservoirs in other blocks in the future.

Effects of farmyard manure and chemical fertilizer application rates on soil biology, cotton and fiber yield

Organic and inorganic fertilizers have significant effect on plant physiology, yield per unit area, available plant nutrient contents and extracellular enzyme activities of soils. This study was carried out in field conditions in arid and semi-arid regions between 2020-2021 years, May 01. The effects of farmyard manure (FM) (20, 40, 60 Mg ha-1) and chemical (CF) (350 kg urea ha-1, 100, 200, 300 kg DAP ha-1) fertilizers applied at different rates on plant nutrient (N, P, K, Ca, Mg, Fe, Cu, Zn and Mn) contents, SPAD value and NDVI of cotton plants, seed cotton yield and soil enzymes (urease, catalase, dehydrogenase, alkaline phosphatase) were investigated. The results showed that FM applications significantly (p<0.01) increased the plant macro and micronutrients compared to CF applications, except for N (200 + 150 kg urea ha-1), Zn and Cu (300 kg DAP + 200 + 150 kg urea ha-1) in the 2021 cotton growing season. Mineralization of FM is slow under natural conditions; therefore, the use of FM alone is not sufficient to meet the nutrient needs of high yielding varieties. Urease and dehydrogenase activities increased significantly in FM treated soils compared to CF, while no significant (p<0.01) increase was recorded in alkaline phosphatase and catalase activities. Farmyard manure is a useful management practice for increasing soil biological activity. Physiological parameters of NDVI, SPAD and seed cotton yield significantly increased in FM treated soils compared to CF applications. The increase in cotton yield was 29.15%, in NDVI value was 22.38% and in SPAD value was 121.7%. The main issues with cotton in the area are the low organic carbon content of the soils, high clay content, arid and semi-arid soils, and their detrimental impact on the uptake of particular nutrients (N, P and B).

Batch Electrocoagulation Process for the Removal of High Colloidal Clay from Open-Cast Coal Mine Water Using Al and Fe Electrodes

Open-cast coal mining operations can produce water with high amounts of total suspended solids (TSS). We tested the use of electrocoagulation for the removal of colloidal clay from mine water. Monopolar batch electrocoagulation was performed at the laboratory scale using Al and Fe electrodes and varying the DC current (0.5, 1, and 2 A) and contact time (15, 30, and 45 min). Aluminum electrode electrocoagulation with a current of 2 A and a contact time of 15 min had the greatest TSS removal efficiency (99%), with concentrations decreasing from 5,400 to 23 mg/L. The greatest removal (98 and 99%, respectively) was obtained using an Al electrode with an electric current of 0.5 and 1 A, with 30 min of contact time. With an Fe electrode, the greatest efficiency was achieved with a current of 2 A and a contact time of 30 min. The TSS removal efficiency reached 98% while the concentration dropped to 66 mg/L, followed by 89% and 95% for the 0.5 A-45 min and 1 A-15 min variations, respectively.

Utilizing Magnesium Carbonate Induced by CO2 to Modify the Performance of Plastic Clay

Highly plastic clays pose significant challenges in engineering projects. Various techniques have been employed to enhance their properties, though many face difficulties related to implementation and environmental impact. This study examines the effect of CO2-induced magnesium carbonate on improving the geotechnical behavior of plastic clay. CO2-induced magnesium carbonate was produced via mineral carbonation and used to improve the behavior of highly plastic natural clay. CO2 gas was injected into a sodium hydroxide solution to produce carbonate ions (CO32−). Magnesium carbonate was precipitated on a laboratory scale by adding magnesium sulfate solution to the carbonate ion solution. Clayey soil samples were obtained from test pits in the Meyghan Plain near Arak, Iran. The clay samples were treated with different percentages of the produced magnesium carbonate. Various parameters of the treated and untreated samples, including index properties, unconfined compressive strength, consolidation behavior, and swelling potential, were studied. It was found that the liquid limit and plasticity index of the treated clay decreased as the magnesium carbonate content increased. The soil classification changed from high plastic clay (CH) to low plastic silt (ML) with the addition of 15% magnesium carbonate to the highly plastic clay. The unconfined compressive strength of the treated clay increased. Additionally, the consolidation behavior and swelling index of the treated clay improved as the magnesium carbonate content increased. This study confirms that CO2-induced magnesium carbonate is a promising material for improving the behavior of highly plastic clays, offering a sustainable approach to environmental management.

Effectiveness of Anaerobic Soil Disinfestation for Weed and Nematode Management in Organic Sweetpotato Production

Weeds and nematodes are particularly problematic in organic sweetpotato production due to a lack of effective pesticides. Anaerobic soil disinfestation (ASD) has the potential to fit into current pest management practices as an alternative to pesticide application. Greenhouse studies were conducted at the Clemson Coastal Research and Education Center (CREC) in Charleston, SC, to investigate the impact of carbon source amendment and a no carbon source treatment, and soil type on cumulative anaerobicity, weed control, nematode population, and sweetpotato vigor. Microcosms were filled with one of three different soil types (Charleston—loamy/native; Blackville—high coarse sand content; and Clemson—high clay content) and were mixed with cottonseed meal (CSM) or no carbon amendment. The pots were then sealed with plastic totally impenetrable film (Tif) for 6 weeks, followed by the transplanting of sweetpotato (cv Bayou Belle) slips. The results suggested that the CSM-treated microcosms spent more time under anaerobic conditions than those treated with the no carbon amendment. The microcosms that experienced a longer duration of anaerobicity had a lower percent weed cover (49%), fewer nematode egg masses, and a lower gall index when compared to microcosms which experienced a shorter duration of anaerobicity. Significantly higher instances of leaf necrosis were observed in the sweetpotato slips sown in the CSM-treated microcosms. The addition of CSM as a carbon source to facilitate ASD resulted in similar above-ground biomasses of the sweetpotato plants compared to the treatments containing no carbon amendment. However, a significantly lower below-ground biomass of the sweetpotato plants was observed in the CSM-treated microcosms.