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This investigation examines the effect of clamshell ash (CSA) and lime additives on the physico-mechanical characteristics of kaolinite clay soil stabilized at the optimum silica fume content. Laboratory tests were performed to assess plasticity, shrink-swell characteristics, compaction characteristics, unconfined compressive strength (UCS), shear strength characteristics, mineralogical and morphological microstructure characteristics of stabilized soil specimens. The kaolinite clay soil was stabilized at its optimum silica fume content (6%) to produce the highest strength and was altered with three non-identical proportions of clamshell ash and lime (3%-9%). Cylindrical soil specimens, 76 mm in height and 38 mm in diameter, were moulded and treated for curing periods of 1, 7, 14, and 30 days to examine the strength of the altered soil. The findings revealed that, adding clamshell ash and lime significantly alters the plasticity, shrink-swell, maximum dry unit weights, and optimum moisture contents of the silica fume-stabilized soil. In terms of strength, the beneficial effects of CSA and lime additives were found to be more significant with more extended curing periods. Incremental increases in curing periods resulted in further enhancements in UCS, cohesion, and internal friction angle, indicating continued strength development over time. Microstructural analysis using field emission scanning electron microscopy and X-ray diffraction provided insights into the interparticle bonding mechanisms and microstructural changes induced by the addition of CSA and lime. The emergence of cementitious phases and pozzolanic responses between soil particles and stabilizers contributed to the densification and strengthening of the stabilized soil matrix. The findings of this study provide valuable insights into the potential of clamshell ash and lime additives to enhance the engineering properties of kaolinite clay soil stabilized with silica fume. These results have implications for sustainable soil stabilization practices, offering a promising approach to improve the performance of soils for various engineering applications, including construction and geotechnical projects. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful thermophilic composting of shrimp sludge through self-heating. • Clean nitrogen (ammonia) recovered used for high-value microalgae cultivation. • Shrimp sludge compost application as soil conditioner for enhanced mango growth. Due to the rapid growth of the aquaculture industry, large amounts of organic waste are released into nature and polluted the environment. Traditional organic waste treatment such as composting is a time-consuming process that retains the ammonia (NH 3) in the compost, and the compost produced has little economic value as organic fertilizer. Illegal direct discharge into the environment is therefore widespread. This study investigates the recovery of NH 3 through thermophilic composting of shrimp aquaculture sludge (SAS) and its application as a soil conditioner for the growth of mango plants. A maximum composting temperature of 57.10 °C was achieved through self-heating in a 200 L bench-scale reactor, resulting in NH 3 recovery of 224.04 mol/ton-ds after 14 days. The addition of calcium hydroxide and increased aeration have been shown to increase NH 3 volatilization. The recovered NH 3 up to 3 kg-N can be used as a source of clean nitrogen for high-value microalgae cultivation, with a theoretical yield of up to 34.85 kg-algae of microalgae biomass from 1 ton-ds of SAS composting. Despite the high salinity, SAS compost improved mango plant growth and disease resistance. These results highlight the potential of SAS compost as a sustainable source of clean nitrogen for microalgae cultivation and soil conditioner, contributing to a waste-free circular economy through nutrient recycling and sustainable agriculture. [ABSTRACT FROM AUTHOR]

The principle of sustainable fertilisation in modern agriculture, which ensures that the soil is maintained in a fertile state requires the search for alternatives to manure fertilisation for products based on humic substances to increase the organic matter content of soils.The advantage of leonardite over conventional natural and organic fertilisers is mainly due to its high content of organic matter and humic substances (humic and fulvic acids). Leonardite, due to the presence of humic acids in it, can be suitable for soil amendment and yield of barley. In the conducted studies, the yield increase after adding Rosahumus fertilizer to the soil at a rate of 6 kg.ha−1 + NPK (Nitrogen, Phosphorus, Potasssium) was found to be 11% compared to the control (NPK).There were no changes in the Corg. content of the soil as a result of the application of Rosahumus fertilizer with NPK. The fertilizer only slightly modified the fractional composition of humus. In the future, we should expect an increase in the use of leonardite-derived humic substances in fertilizers and soil conditioners to stabilize soil organic matter. [ABSTRACT FROM AUTHOR]

In this study, the effects of some soil conditioners (zeolite, hydrogel, peat) on the yield, yield components, and water use efficiency (WUE) of soybean (Glycine max L.) were investigated in two different irrigation regimes. The study was handled in a polycarbonate-greenhouse located in Hatay Mustafa Kemal University, Türkiye, according to a completely randomized factorial design with three replications using the Agroyal variety of soybean as plant material. In a control group, three doses of hydrogel (40, 80, 120 kg ha−1), zeolite (500, 1000, 1500 kg ha−1), and peat (500, 1000, 1500 kg ha−1) were used as treatments under two irrigation regimes as I1 (irrigation made when the water fell up to %10 of the field capacity) and I2 (irrigation made when the water fell up to %50 of the field capacity). It was observed that some doses of the soil conditioners have a positive effect on the examined parameters. However, deficit irrigation decreased or inhibited the positive effect of soil conditioners. According to the results, zeolite application gave the most beneficial results under both two-irrigation management. [ABSTRACT FROM AUTHOR]

Organic polymers have been extensively studied over the last decades, and most of the research focused on the mechanical performance of the soils treated with polymer at different dosages without addressing the effects of the unique polymer characteristics such as molecular weight and concentrations of polymer solutions. This paper investigates an anionic polyelectrolyte, sodium polystyrene sulfonate (PSS) as a soil stabilizer. The effects of the molecular weight of PSS, concentrations of PSS solutions, and the dosages on the strength of a siliceous sandy subgrade soil are examined. Fracture toughness of the PSS-treated soil is determined and discussed based on semicircular bending test. Three molecular weights (1,000,000, 200,000, and 70,000 g/mol) along with solution concentrations of 10%, 17%, 23%, and 30% by weight are considered. The dosages of PSS solutions at 2%, 4%, 6%, and 8% by weight of dry soil are discussed. All the dosages studied showed strength improvement of the sandy soil that increased with concentrations of the PSS solutions as well as the increasing dosages. PSS with the highest molecular weight performed the best among all three molecular weights. The addition of the organic polymer also improved the fracture toughness of the soil, indicating better resistance to crack propagation. The stabilization mechanism in terms of particle linkage and aggregation morphology are examined using scanning electron microscope. Aggregation of the fine soil particles and binding between the fine and coarse soil grains are observed and discussed, which contribute to the improvement of mechanical strength of the soil. [ABSTRACT FROM AUTHOR]

AbstractThe soil can be managed to improve plant nutrition and resilience under water scarcity. The objective of this study was to evaluate the contribution of soil conditioners, controlled-release fertilizers, and water availability levels to mitigate water scarcity and improve the nutrition of coffee plants. The experiment was conducted in a greenhouse under a randomized block design with four replicates in a factorial scheme (2 irrigation levels × 2 fertilizer types × 5 soil conditioners) of analysis of variance. The factors under study were two irrigation levels (low—40% of water holding capacity, and high—80% of water holding capacity), fertilizer type (conventional and controlled-release), and soil conditioners (coffee husk, gypsum, water-retaining polymer, organic compost, and control without soil conditioner), The characteristics assessed were soil fertility, soil moisture, and nutrient foliar contents. Multivariate analytical methods were used to interpret the results. Soil moisture, chemical attributes, and leaf nutrient contents were analyzed. There was a similarity in the clusters formed by the controlled-release fertilizer treatments, which contribute to plant nutrition. Even under water restriction, the treatments with coffee husk and organic compost were clustered along with soil moisture, favoring the absorption of nutrients. Soil cover with organic compounds improved soil moisture, even under low water availability, which favored plant fertility and nutrition. [ABSTRACT FROM AUTHOR]

Excessive fertilizer input, low nutrient use efficiency, soil quality, and environmental degradation hinder greenhouse vegetable production. Integrated agronomic strategies of soil, crop, and nutrient management are needed to sharply improve the vegetable yield and simultaneously maintain sustainable production. A three-season field experiment was conducted from 2015 to 2018, aiming to evaluate the effect of integrated soil–crop system management (ISSM) on the agronomy, environment, and economy of greenhouse vegetable systems in the Yangtze River Basin, China. Three treatments were included in the experiment: (1) farmers' current practice (FP), based on a local farmers' survey; (2) soil remediation treatment (SR), the application of soil conditioner and compost fertilizer instead of chicken manure; (3) ISSM, a combination of soil conditioner, reducing plant density, and using formula fertilizer as well as increasing the fertilization times. The results indicated that ISSM (47.7 Mg ha−1) improved the pepper yield by 17% relative to farmers' current practice (FP, 40.7 Mg ha−1). Soil remediation (SR), as a single approach, mainly made a contribution to improving the yield (by 6.9%) and nutrient use efficiency while reducing apparent nitrogen (N) losses. Higher yields were mainly attributed to increasing the fruit number per plant. On average, apparent N losses were reduced by 245 kg N ha−1 per season for ISSM compared to FP. In addition, higher net profits were obtained under SR and ISSM relative to FP. Overall, both SR and ISSM have advantages for the agronomy, environment, and economy in greenhouse vegetable production, but ISSM would be the optimal choice to achieve higher yields with lower environmental impacts. [ABSTRACT FROM AUTHOR]

Small slaughterhouses generate biowaste, which for economic reasons, is generally destined for composting. Inoculating appropriate microorganisms can improve biodegradation efficiency and mitigate odor generation during the composting process and can give rise to composts with neutral or pleasant odors. Therefore, the aim of this study was to compare the odor intensity reduction of compost generated with and without a formulated inoculum (Saccharomyces cerevisiae, Bacillus subtilis, and Rhodopseudomonas palustris). A set of experimental data was collected and analyzed according to the German "Verein Deutscher Ingenieure" odor protocol. The results showed that adding microorganisms was effective in reducing unpleasant odors in all three composts generated from swine, cattle, and poultry slaughterhouse by-products during both summer and winter seasons. Additionally, soil odor was predominant in composts that were inoculated in the two tested seasons (i.e., summer and winter). On the other hand, composts without inoculation had odors similar to peat for swine compost, ammonia for cattle compost, and manure for poultry compost, regardless of the season tested. Overall, composting process with appropriate inoculum can help in the correct disposal of slaughterhouse wastes by transforming organic matter into composts, which can have economic and environmental value as a soil conditioner and/or fertilizer. [ABSTRACT FROM AUTHOR]

An initial investigation into the utilization of recycled plant and animal residues as soil amendments (SAs), including compost, biochar, and soil conditioner, was conducted using alfalfa crops. This study evaluated the impact of SAs on alfalfa seed germination, resulting in an 87% germination rate for biochar, 82% for soil conditioner, and 82% for compost. In comparison, untreated seeds displayed a 78% germination rate. After successful germination, the SAs were employed to enhance soil health, with a focus on water conservation and increased forage yield. The study used sandy-textured soil with moderate alkalinity, very slight salinity, slight calcareousness, and high permeability. The germination trial confirmed that SAs usage did not hinder seed germination, even for salt-sensitive crops like alfalfa. Two field experiments were carried out in Al-Wafra, using different application rates of compost, biochar, and soil conditioner at 5, 7.5, and 10 tons per hectare. The results highlighted the positive impact of SAs application on increasing forage production, with varying degrees of enhancement, and confirmed a 40% reduction in water usage compared to treatment without SAs but under 100% irrigation (100% ETc). In conclusion, SAs show promising potential for local forages intensification and water conservation. [ABSTRACT FROM AUTHOR]

In response to the environmental concerns posed by cadmium (Cd) contamination, the application of nano‐submicron mineral‐based soil conditioner (MSC) as a potential soil amendment has garnered interest due to its promising Cd mitigation properties. In this study, we aimed to investigate the solidification capacity and mechanism of Cd in MSC and examine the phase and morphology changes following solidification. Systematic experiments were conducted to assess the solidification capacity of MSC for Cd, revealing an impressive efficiency of nearly 100 % even at Cd concentrations of approximately 800 mg/L. The solidification efficiency was found to be positively correlated with the pH value, significantly declining as the environment shifted from pH>7 to pH<7. Notably, under alkaline conditions (pH>7), Cd solidification in MSC was primarily attributed to the Cd‐OH complex formed on the surface of MSC and aided by cation‐exchange reaction. In contrast, under acidic conditions (pH<7) and exposure to extreme Cd concentrations, Cd(OH)Cl precipitation became the dominant mechanism for solidification. Interestingly, the presence of KCdCl3, a water‐soluble phase, did not significantly contribute to the overall solidification efficiency. These findings provide valuable insights into the solidification mechanism of Cd in MSC and offer potential implications for soil remediation efforts targeting Cd contamination. [ABSTRACT FROM AUTHOR]

This study was carried out in Bolu conditions in 2021 to see the effect of poultry ash, which has the potential to be a nutrient in terms of being rich in minerals and is also a soil conditioner, on the yield and quality characteristics of potato (Solanum tuberosum L.). In the study, the conventional production method of 8 kg/da P + 20 kg/da N application was tried with six different ash amounts (0, 500, 1000, 1500, 2000 kg/da poultry ash + 20 kg/da N). According to the values obtained from the study, the highest plant height (cm), the number of main stems (pieces), the specific gravity (g) 1500 kg/da ash application, the number of tubers per plant (pieces) from farmer conditions; average tuber weight (g), french fries oil rate (%), protein rate (%), big tuber rate (%) 2000 kg/da; chips oil rate (%), small tuber rate (%), dry matter rate (%) in the control plot where there was no application; Tuber yield per decare (kg/da), medium tuber ratio (%), marketable tuber ratio (%), were obtained from 1000 kg/da poultry ash application. [ABSTRACT FROM AUTHOR]

Volcanic tuffs rich in chabazite zeolites have been extensively examined for their potential to enhance soil properties and increase fertilizer efficiency, both in their natural state and when enriched with nitrogen (N). However, there is a scarcity of data regarding their utilization in acidic sandy soil, particularly when used alongside organic fertilizers. This paper presents the findings of a 50-day laboratory incubation study that investigated the dynamics of N pools in an acidic sandy-loam agricultural soil treated with various N sources. These sources included urea, N-enriched chabazite zeolite tuff, and pelleted composted manure applied at a rate of 170 kg N/ha. Additionally, the N sources were tested in combination with chabazite zeolite tuff mixed into the soil to assess its role as a soil conditioner. The results revealed distinct behaviours among the tested N sources, primarily impacting soil pH and N dynamics. Soil fertilized with manure exhibited slow N mineralization, whereas N-enriched zeolite displayed a more balanced behaviour concerning net NO3−-N production and NH4+-N consumption. Both N-enriched zeolite and urea temporarily altered the soil pH, resembling a "liming" effect, while pelleted manure facilitated a prolonged shift towards neutral pH values. Considering the water adsorption capacity of zeolite minerals, caution is advised when adjusting water content and employing combustion methods to measure soil organic matter in zeolite-treated soil to avoid potential inaccuracies. In summary, N-enriched chabazite zeolite tuff emerged as a valuable N source in acidic sandy-loam soil, offering a promising alternative to synthetic fertilizers and showcasing a sustainable means of N recycling. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effect of the application of different organic matter, UGmax soil conditioner and simplifications in potato cultivation on the content of dry matter, starch and sugars in tubers of the medium-early edible cultivar 'Satina' after harvest and after long-term storage. The highest dry matter (173.4 g kg−1) and starch (124.6 g kg−1 f. m.) content was obtained with the simultaneous application of a manure with soil conditioner at 100% mineral fertilization. In the case of sugars, the withdrawal of the soil conditioner from the crop proved most beneficial, for total sugars on the stubble intercrop (5.06 g kg−1 f. m.) and for reducing sugars (1.99 g kg−1 f. m.) in the case of straw treatment. Each protection reduction applied resulted in a significant reduction in starch content. In this regard, the withdrawal of herbicides with the simultaneous application of manure and UGmax proved most beneficial. Long-term storage of tubers caused a significant reduction in their quality in terms of dry matter and starch content (average by −3.6 and −2.3%, respectively) and an increase in total and reducing sugars (average by 11.8 and 9.6%, respectively). The decrease in dry matter and starch content was significantly influenced by the 50% reduction in NPK fertilization applied during the growing season, while the application of soil conditioner with full protection contributed to the increase in reducing sugars after storage at 28.9 pts%. Our research is in line with current trends of used potato cultivation technologies focused mainly on environmental protection, so the results of this study can provide a basis for validation for researchers currently engaged in such evaluation. [ABSTRACT FROM AUTHOR]

Manganese toxicity is a major obstacle to agriculture in acid soils. Dark pericarp disease (DPD) is a newly spread physiological disorder induced by excess Mn in litchi, leading to undesirable fruit appearance and substantial economic loss. In this work, broadcast of alkaline soil conditioner in winter, followed by foliar sprays of ascorbic acid and sulfur solution at fruit development, was adopted to examine the effect of these combinations on DPD alleviation in a litchi orchard, with DPD morbidities of 70~85% in recent ten years. The combination of soil conditioner broadcast and foliar water spray was used as the control. At harvest, DPD incidence was significantly decreased by sulfur spray (3.3 ± 1.0%) and slightly reduced by ascorbic acid spray (10.7 ± 8.0%) compared to the control (12.9 ± 7.6%). Soil pH and available Mn were significantly increased and reduced by the soil conditioner broadcast. Sulfur spray significantly inhibited Mn uptake but enhanced the accumulation of Mg, Ca, sugars and cyanidin-3-rutinoside in the pericarp, leading to improved fruit pigmentation. Antioxidase activities were regulated to resist Mn stress by sulfur spray. The spray of ascorbic acid could not mitigate DPD as expected, probably due to the dose used. Conclusively, this study provides a practicable approach to mitigate Mn phytoavailability in acid soils. [ABSTRACT FROM AUTHOR]

Fine-grained soils present engineering challenges. Stabilization with marble powder has shown promise for improving engineering properties. Understanding the temporal evolution of Unconfined Compressive Strength (UCS) and geotechnical properties in stabilized soils could aid strength assessment. This study investigates the stabilization of fine-grained clayey soils using waste marble powder as an alternative binder. Laboratory experiments were conducted to evaluate the geotechnical properties of soil–marble powder mixtures, including Atterberg's limits, compaction characteristics, California Bearing Ratio (CBR), Indirect Tensile Strength (ITS), and Unconfined Compressive Strength (UCS). The effects of various factors, such as curing time, molding water content, and composition ratios, on UCS, were analyzed using Exploratory Data Analysis (EDA) techniques, including histograms, box plots, and statistical modeling. The results show that the CBR increased from 10.43 to 22.94% for unsoaked and 4.68 to 12.46% for soaked conditions with 60% marble powder, ITS rose from 100 to 208 kN/m2 with 60–75% marble powder, and UCS rose from 170 to 661 kN/m2 after 28 days of curing, molding water content (optimum at 22.5%), and composition ratios (optimum at 60% marble powder). Complex modeling yielded R2 (0.954) and RMSE (29.82 kN/m2) between predicted and experimental values. This study demonstrates the potential of utilizing waste marble powder as a sustainable and cost-effective binder for soil stabilization, transforming weak soils into viable construction materials. [ABSTRACT FROM AUTHOR]

Soil mulches and conditioners have been shown to improve soil moisture conservation, infiltration, and seed germination and survival, but their interactive effects with sporadic rainfall and the existing vegetation have rarely been considered. In an experimental field study, we assessed the effects of soil additives (sawdust and hydrogel) and mulches (river sand and plant debris) on seedling emergence and survival of Astragalus nigricans Barneby, in the rangelands of Mashhad, northeast Iran. We also assessed any effects on soil moisture and temperature several days after rain in July 2017 and May 2018 and weed composition, density, and diversity. The most successful treatment was hydrogel, associated with earlier seedling emergence for A. nigricans, greater seedling survival, and biomass production. Sawdust and sand treatments were useful for root proliferation and seedling emergence in the spring of the first season, but they led to high seedling mortality under drought. Debris of Artemisia khorasanica shoots was the most efficient and consistent treatment for soil moisture conservation and temperature stability in both years, but its possible allelopathic effects led to high seedling mortality and a long delay (41 days) on seedling emergence. Plant debris also negatively affected the density, richness, and diversity of nontarget plant species. Despite differences among different rainfall events, mulch treatments have an important role in regenerating degraded rangelands. [ABSTRACT FROM AUTHOR]

The incorporation of waste materials into cementitious binders serves as a strategy to diminish waste volume and lower carbon emissions. This study presents an in-depth evaluation of calcium carbide residue and coal fly ash as alternative binders. The assessment of raw materials emphasized their chemical composition and potential for pozzolanic reactions. Based on these factors, the optimal ratio of Ca/(SiO2 + Al2O3) in the raw materials was determined to be 1.5. Therefore, this study was designed to vary the raw material composition with a CaO/(SiO2 + Al2O3) ratio ranging from 1.7 to 0.9. Upon investigating the effect of the raw material proportion on the compressive strength of pastes and mortars, the composition yielding the highest compressive strength was selected for its potential application as a stabilizer for loess soil. A mixture of calcium carbide residue and coal fly ash with a Ca/(SiO2 + Al2O3) ratio of 1.5 resulted in the highest compressive strength at long curing periods in both pastes and mortars. Mineralogical and microstructural analyses revealed several products, beyond those formed from the pozzolanic reactions, that occurred and enhanced the compressive strength of samples. The highest performing mixture of carbide residue and coal fly ash was then used to stabilize loess soil at 10–25 wt%. The unconfined compressive strength, along with mass and strength loss due to wetting and drying cycles, was also studied. It was observed that the unconfined compressive strength of the stabilized soils remained consistent after six wet-dry cycles but decreased after twelve cycles due to microcracks. The findings suggest that carefully designed mixtures based on the chemical interactions of calcium carbide residue and coal fly ash can offer a sustainable, efficient approach for soil stabilization, potentially revolutionizing construction practices. [ABSTRACT FROM AUTHOR]

Soil stabilization, crucial for enhancing the stability and engineering properties of soil, has been the subject of extensive research utilizing mechanical and chemical methods. This study delves into the challenges faced in traditional soil subgrade stabilization methods, stemming from factors such as soil erosion, inadequate load-bearing capacity, and susceptibility to environmental conditions. These challenges have prompted the exploration of innovative solutions for road subgrade soil stabilization. Our primary motivation stems from the limitations of conventional techniques and the pressing need to address issues like resource exploitation and environmental pollution. Geopolymers, specifically alkaline-activated materials, have emerged as a promising alternative for soil stabilization. This research investigates the effects of geopolymer blended with rice husk ash (RHA) and fly ash (FA) on various geotechnical properties of natural and admixed black cotton soil. The soil is replaced with admixtures ranging from 0% to 30% of blended geopolymer by weight. The study provides a comprehensive analysis, focusing on quantifiable improvements in soil properties through numerical results. The investigations consistently reveal that the application of geopolymer as a soil stabilizer results in notable improvements in the geotechnical properties like index properties, strength properties, resistance to penetration (CBR), etc., of problematic soil. Comparative analysis with traditional methods underscores the superiority of the proposed geopolymer blend, showcasing its innovation, sustainability, and cost-effectiveness. The findings of this study contribute to the advancement of soil stabilization techniques, specifically in the context of geopolymer applications. For future work, this study suggests an in-depth exploration of geopolymer-stabilized soil's long-term durability and environmental impact. Additionally, further research could focus on optimizing the geopolymer blend ratios for varying soil types and environmental conditions. [ABSTRACT FROM AUTHOR]

Mediterranean agriculture asks for sustainable strategies to prevent actual soil organic matter decline rates. Composting agri-food by-products for application in farmland, besides contributing to a circular economy at regional or local scales, may improve soil resistance to physical degradation. Aggregate stability (AS) is a crucial property for building up such resistance. Olive pomace is an abundant by-product of the olive oil industry that may be valorized through composting. This study aimed to assess the influence on AS of olive-pomace-based composts (OPC) applied to a sandy loam Leptosol and a clay loam Fluvisol. To assess the effects of compost characteristics on AS, three OPCs resulting from different olive pomace proportions in the composting raw material (44, 31, and 25% by volume) were applied to aggregate samples in three doses (10, 20, and 40 t.ha−1, plus control) with fine and coarse grain sizes. Controlled laboratory conditions subjected samples to daily wetting-drying cycles during a 30-day experiment. AS was measured by wet sieving. OPC application significantly increased AS in the Leptosol amended with fine (+15% vs. control) and coarse (+19%) grain-size compost. In well-aggregated Fluvisol, amendment induced a significant increase in AS only in the compost coarse grain size (+12%). The application dose significantly affected AS, with 10 t.ha−1 being the best-performing dose. OPC applications in weakly aggregated soils are seemingly an encouraging soil management practice for improving soil resistance to physical degradation and reducing soil organic matter decline rates in Mediterranean farmland. [ABSTRACT FROM AUTHOR]

This document is a discussion of a research paper titled "Probing the Stochastic Unconfined Compressive Strength of Lime–RHA Mix Treated Clayey Soil." The paper explores the use of lime and rice husk ash as binders to stabilize clayey soil. The authors conducted tests to measure the unconfined compressive strength of soil-binder specimens with varying amounts of rice husk ash and lime. They used artificial neural networks and Gaussian process regression to analyze and predict the data. The discussers raise questions about the influence of suction on the strength of the blends and the effect of dry density, suggesting further evaluation of these factors. [Extracted from the article]

The conducted investigation encompassed the comprehensive integration of mechanical, environmental, chemical, and microstructural evaluations of a composite amalgamating sandy soil and a synthetic polymer at two distinct concentrations (2.5% and 5%) across multiple curing intervals (0, 1, 2, 4, 7, 15, 30, and 45 days). The studied soil originates from an environmentally significant protected area in Brazil. The implementation of mechanisms for soil improvement in the region must adhere to technical criteria without causing environmental harm. Direct shear testing was conducted, permeability was assessed, and microstructure analysis and XRD and XRF/EDX studies of both the soil and composites were conducted. It was observed that longer curing times yielded improved results in shear stress, friction angle, and cohesive intercept, with SP_5% exhibiting the highest values compared with the soil and SP_2.5%. Adding the polymeric solution to the soil contributed to cementation and cohesion gains in the substrate. Through microstructural characterization, the polymer's role as a cementing agent for the grains is evident, forming a film on the grains and binding them together. Based on the analyses and studies conducted in the research, it can be concluded that there is technical feasibility for applying the polymeric solution at both dosages in geotechnical projects. [ABSTRACT FROM AUTHOR]

To ensure adequate nutrition for the growth of maize (Zea mays L.) in sustainable agriculture, it is necessary to apply bio-agent soil conditioner and manure. This study aims to determine the effect of doses of bioagent-ameliorant and chicken manure on growth and yield components. The research was conducted in highland with an altitude 800 m above sea level. This study used an experimental method with two sets of experiments, namely experiments using one and two-cobs maize cultivars. The experiment used a randomized block design (RBD) with two treatment factors and three replications. The first treatment factor was the dose of bioagent ameliorant, which consisted of 3 levels, namely 0, 7.5, and 15 kg/ha, while the second factor was the dose of chicken manure, which consisted of 3 levels, namely 0.5 and 10 tons/ha. The observed growth components were plant height and number of leaves, while the yield components observed were cob length, cob diameter, cob weight per plant, and cob weight per plot. In research on two-cob maize experiment, there was no interaction effect between doses of soil conditioner and chicken manure, while the interaction effect on plant height occurred in one-cob maize experiment. The single effect of ameliorant doses could not increase all components of growth and yield, both in one and two-cob maize cultivars. The single effect of doses of chicken manure increased number of leaves, cob length, cob weight per plant, and cob weight per plot in one-cob maize cultivar, while increased plant height in two-cob maize cultivar. [ABSTRACT FROM AUTHOR]

Fertilizer is one of the crucial inputs to maximize nutrients needed by plants, especially rice. However, insufficient ameliorant application may affect the fertilizers' effectiveness. Humic acid is believed as one of the ameliorants to improve soil conditions resulting in higher nutrient availability. The study aimed to evaluate the effect of combining humic acid and micronutrients on growth, production, and nutrient contents in rice. Three treatments were applied, i.e., control (without humic acid), humic acid, and humic acid + micronutrients. The result showed that both humic acid treatments produced the highest number of tillers, humic acid application solely stimulated the highest root length, and humic acid + micronutrients stimulated the highest plant height, and fresh and dry biomass weight. Grain weight was not affected by treatments, but humic acid + micronutrients gave a higher weight of milled grain and number of filled grains. Humic acid application solely resulted in plant biomass and grains having higher N, P, and K contents. Overall, the application of humic acid + micronutrients is recommended to increase rice production. [ABSTRACT FROM AUTHOR]

Humic substances are naturally occurring materials composed of complex biogenic mixtures of substituted aromatic and aliphatic hydrocarbon core materials derived from the degradation and decomposition of dead plant and animal matter. They are ubiquitous in both terrestrial and aquatic systems constituting biotic pools and are characterized by unique properties; they are amphiphilic redox compounds with exceptional chelating features. Humic substances play a crucial role in both agriculture and the environment as carbon sequestrators, soil improvers, plant health promoters, as well as stabilizers of soil aggregates and regulators of organic/inorganic nutrients bioavailability. This review article attempts to summarize current knowledge about the molecular nature and characterization techniques employed for the study of humic substances worldwide as the chemistry of their components differs markedly and depends on natural processes, several abiotic and biotic factors, the origin of the organic matter, and their complexation with inorganic, e.g., metal-ion, compounds. This work is equally concerned with the association of humic substances with dyes, a notorious pollutant, responsible for various environmental issues generally arising from the discharge of untreated effluents into soils and water bodies. Azo dyes, in particular, negatively affect soil microbial communities, as well as plant germination and growth. The aim is to feature the potential contribution of humic substances as novel materials for environment-friendly and sustainable processes. [ABSTRACT FROM AUTHOR]

Feacal sludge (FS) management is a growing concern in the Global South. Research has shown that FS has a potential for reuse in agriculture due to its high nutrient content. However, it contains many pathogens which present a public health and environmental risks when it is applied to land without proper treatment. Composting is one of the viable options for sanitizing FS biosolids before reuse in agriculture as a soil conditioner. However, pathogen die-off during FS composting and factors responsible for pathogen survival in compost are not well understood. Therefore, we conducted a systematic review to better understand pathogen inactivation during FS composting. The results revealed that although most pathogens are inactivated by the temperature generated during composting, spore-forming bacteria, helminths, and viruses are likely to survive the process. The findings indicated that although temperature-time is the major factor responsible for pathogen inactivation during composting, other factors (change in pH, moisture content, turning frequency, nutrient depletion, toxic by-products) and mechanisms (indigenous microbial activities, microbial antagonistic effect, antibiotic action) also have an influence. In addition, most studies on pathogen inactivation during FS composting are usually based on the use of indicator microorganisms and there are limited studies on specific pathogens. Hence, further research on virus, protozoa and antimicrobial resistance inactivation during FS composting as well as the role of factors and mechanisms involved in the composting process is needed. This research will generate vital formation to inform the design, operation, and optimization of FS composting facilities to produce pathogen-free compost. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of different types of natural cellulose-based fillers on the properties of Xanthan gum (XG) in order to develop novel bio-based soil conditioners (SCs) that could be used in forestry and agricultural applications. Rheological measurements highlighted that SCs with cellulose fillers characterized by a high aspect ratio and low oxide ash content exhibited an average increase of 21% in yield stress compared to neat Xanthan gum. The presence of cellulose fillers in the composites resulted in a slower water release than that of neat XG, limiting the volumetric shrinkage during the drying process. Furthermore, an analysis of the water absorption and water retention capacity of soils treated with the different SCs was carried out, demonstrating that the addition of 1.8 wt.% of SC with optimized composition to the soil led to an increase in water absorption capacity from 34% up to 69%. From the soil water retention curves, it was observed that the addition of SCs significantly increased the amount of water effectively available for plants in the area between field capacity and permanent wilting point (100–1000 kPa). From practical experiments on grass growth, it was observed that these SCs improved the water regulation of the soil, thus increasing the probability of plant survival under drought conditions. [ABSTRACT FROM AUTHOR]

A quantitative study of the biodegradability of polymer soil conditioners is necessary for a reasonable prediction of their stability and functioning in soils. For this purpose, a new methodological approach based on PASCO (USA) equipment was proposed. This approach allows recording continuous kinetic curves of CO2 emission in laboratory experiments based on incubation of composite gel-forming soil conditioners. Several characteristic types of respiration curves have been identified, and new physically based models have been proposed for their description with subsequent calculation of the half-lives of composite hydrogels. For the traditionally considered non-biodegradable acrylic superabsorbents of soil water, the possibility of rapid biodegradation was shown for the first time in the case of the addition of a biologically active compost extract into their liquid phase. With this treatment, which brings laboratory experiments closer to real soil conditions, the half-lives of both the well-known European Aquasorb and Zeba superabsorbents and the Russian Aquapastus hydrogel decreased by an order of magnitude from the initial values of 2–6 years to 0.1–0.3 years. In practice, this can negatively affect the profitability of using such materials for soil conditioning due to their rapid destruction and loss of functionality. The addition of silver ions into innovative Aquapastus composite superabsorbents at a dose of 0.1% or 10 ppm in swollen gel structures effectively reduces their biodegradability, prolonging the half-life to 10 years or more, which is twice the German standard DüMV 05.12.12 of the stability of polymer ameliorants. [ABSTRACT FROM AUTHOR]

• Renewable energy is essential to support biowaste valorization; • Soil conditioner outperforms peat in 14/18 categories, with notable carbon savings; • Cogeneration resulted to be preferable with respect to biomethane upgrading; • Local suppliers and the electricity mix have a role in achieving carbon neutrality. The recent large-scale urbanization and industrialization resulted in an impressive growth of solid waste generation worldwide. Organic fraction generally constitutes a large fraction of municipal solid waste and its peculiar chemical properties open to various valorization strategies. On this purpose, life cycle assessment is applied to an innovative industrial system that processes 18 kt/y of agricultural and livestock waste into a high-quality soil conditioner. The high-quality soil conditioner production system consists of a series of processes, including anaerobic digestion and vermicomposting, allowing the generation of a peat-like material with high carbon content, porosity, and water-holding capacity. The presence of a photovoltaic plant and a cogeneration plant, fed with the biogas produced in the anaerobic digestion, makes the system entirely self-sufficient from the national grid and generating a surplus of electricity of 1177MWh/y. The high-quality soil conditioner showed better environmental performances in 15 out of 18 impact categories when compared to alternative scenarios. In particular, the high-quality soil conditioner and the related biowaste management resulted in a carbon saving of around 397 kg CO 2 eq/ton compared with a scenario involving the employment of peat in place of the high-quality soil conditioner and a traditional biowaste management, and 165 kg CO 2 eq/ton compared with a scenario where cogeneration is replaced by biomethane upgrading. This study demonstrates the possibility of using organic waste as an environmentally sustainable and renewable source for energy and carbon to soil conditioning. [ABSTRACT FROM AUTHOR]

• • Seaweed compost and Pseudomonas koreensis on tomato in saline soils were compared. • • SC + HCH2-3 affected the rhizosphere soil properties and enzyme activities. • • SC + HCH2-3 had significant effects on Pseudomonas , Bacillus and Azospira abundances. • • Seaweed compost and Pseudomonas koreensis can be used as a potential soil conditioner. This study investigated the effects of waste seaweed compost and rhizosphere bacteria Pseudomonas koreensis HCH2-3 on the tomato seedlings growth in coastal saline soils and chemical properties, enzyme activities, microbial communities of rhizosphere soil. Microcosmic experiment showed that the seaweed compost and rhizosphere bacteria (SC + HCH2-3) significantly alleviated the negative effects of salinity on the growth of tomato seedlings. SC + HCH2-3 amendment significantly increased the plant height and root fresh biomass of tomato seedling by 105.59% and 55.60% in the coastal saline soils, respectively. The soil properties and enzyme activities were also dramatically increased, indicating that the nutrient status of coastal saline soil was improved by SC + HCH2-3 amendment. In addition, Proteobacteria, Actinobacteriota and Firmicutes were the dominant phyla in the rhizosphere soil after adding seaweed compost and rhizosphere bacteria P. koreensis HCH2-3. The relative abundances of Massilia , Azospira , Pseudomonas and Bacillus increased in treatment SC + HCH2-3. Especially, the beneficial bacteria genera, such as Pseudomonas , Bacillus and Azospira , were significantly correlated with the increases of contents of total nitrogen, nitrate nitrogen and ammonium nitrogen in tomato rhizosphere soil samples. Consequently, adding waste seaweed compost and rhizosphere bacteria P. koreensis HCH2-3 into coastal saline soil was suggested as an effective method to relieve salt stress of tomato plants. [ABSTRACT FROM AUTHOR]

In this study we investigated the efficacy of a novel material parthenium weed (Parthenium hysterophorus L.) biochar (PBC), iron doped zinc oxide nanoparticles (nFe-ZnO), and biochar modified with nFe-ZnO (Fe-ZnO@BC) to adsorb heavy metals (HMs) and reduce their uptake by wheat (Triticum aestivum L.) in a highly chromite mining contaminated soil. The co-application of the applied soil conditioners exhibited a positive effect on the immobilization and restricted the HMs uptake below their threshold levels in shoot content of wheat. The maximum adsorption capacity was because of large surface area, cation exchange capacity, surface precipitation, and complexation of the soil conditioners. The scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) showed porous smooth structure of parthenium weed derived biochar that helped in HMs adsorption, increase the efficiency of soil fertilizers and nutrients retention which help in the enhancement soil condition. Under different application rates the highest translocation factor (TFHMs) was obtained at 2 g nFe-ZnO rate followed the descending order: Mn > Cr > Cu > Ni > Pb. The overall TFHMs was found <1.0 indicating that low content of HMs accumulation in roots from soil slight transferred to shoot, thus satisfying the remediation requirements. Wheat is considered as an important staple food which is grown in a chromite mining contaminated soil containing toxic HMs releasing from weathering of mafic and ultramafic rocks in the study area. The present research work is significantly beneficial in identifying the efficiency of treatment technologies to immobilize toxic HMs in soil. Parthenium weed derived biochar and biochar modified with nFe-ZnO (Fe-ZnO@BC) reduce the HMs uptake by wheat plant. [ABSTRACT FROM AUTHOR]

This research evaluated several methods to help reduce pivot ruts or wheel tracks on pivots. On-farm trials were established at nine site-years with corn (Zea mays L.), alfalfa (Medicago sativa L.) and wheat (Triticum aestivum L.) during 2020–2022 in Utah and Idaho. The eight-boom design (i.e., Advantage booms) had mostly positive crop responses but did not reduce wheel track depth. The part circle (PC) method provided much shallower tracks at one site, but it also lowered crop yield. At other sites there were minimal effects to yield and quality with the PC method, but the early-season, shallow wheel tracks did not usually last through the heaviest time of irrigating. The low energy precision application (LEPA) method was the most reliable method for maintaining crop yield and quality, while improving wheel tracks. The single boom method often maintained crop quality, but it also often reduced yield, and did not improve wheel tracks compared with the nontreated controls. The polyacrylamide had few effects on crop yield and quality, or wheel track depth. There was no approach in the study that maintained yield and reduced pivot track depth compared with no treatment in every scenario, but the LEPA method displayed the greatest potential for uniformly irrigating the area near the wheel track to maintain crop yield and quality, while minimizing water entering the track, to help reduce burdensome pivot ruts. Thus, LEPA may be one of the most effective sprinkler modifications for reducing pivot tracks and adequately irrigating the area around the track. This research evaluated how several sprinkler modifications and a soil conditioner help reduce pivot ruts or wheel tracks on pivot irrigation systems. On-farm research trials were established at six fields with corn, alfalfa, and wheat during 2020–2022 in Utah and Idaho. The eight-boom sprinkler modification had mostly positive crop responses but did not reduce wheel track depth. The part circle (PC) sprinkler method sometimes reduced wheel rut depth but came at the expense of lost crop production. The low energy precision application (LEPA) sprinkler method was the most reliable method for maintaining crop yield and quality, while improving wheel tracks. The single boom method often reduced yield and did not improve wheel tracks compared with the nontreated tracks. The polyacrylamide soil conditioner had few effects on crop yield and quality, or wheel track depth. There was no approach in the study that maintained yield and reduced pivot track depth compared with no treatment in every scenario, but the LEPA method displayed the greatest potential for uniformly irrigating the area near the wheel track and maintaining crop yield and quality. Thus, LEPA may be one of the most effective tools for reducing pivot tracks and adequately irrigating the area around the track. [ABSTRACT FROM AUTHOR]

A field experiment was conducted in sandy soil under New EL-Salheya conditions, Egypt, to investigate the effect of yeast industrial waste (YIW) and farmyard manure (FYM) both of them alone and combination at 3 different mixtures from studied soil amendments as well as control (without soil amendments) to enhance some chemical and physical properties of sandy soil and corn grain yield. The results demonstrated that soil pH, ECe, Bd, PR, and HC decreased by increasing application of YIW and FYM both of them alone and 3 different mixtures, while the OC, available NPK and MWHC were increased. Also, the results demonstrated that the application treatments of the YIW and FYM increased the corn grain yield. The average increases of corn grain yield were 64.77, 116.73, 182.21, 147.69 and 89.32% with the application treatments of YIW and FYM at T2, T3, T4, T5 and T6, respectively, relative to control. The more effective treatment caused highly increased in corn grain yield was applied mixture treatment of 20 m³ ha-1 YIW+20 Mg ha-1 FYM (T4). So, we can say that the application mixtures from YIW and FYM are considered effective in improvement sandy soil properties and productivity, which reduces environmental pollution from those wastes in the event that they are not used as a soil conditioner. [ABSTRACT FROM AUTHOR]

As a good carbon source and soil conditioner, biochar is widely used in acidic soils but seldom in alkaline soils due to its high pH. In this study, cotton straw biochar was modified with five different acidic materials to obtain wood-vinegar- (WBC), monosodium-glutamate (MSG)-wastewater- (MBC), citric-acid- (CBC), phosphoric-acid- (PBC), and nitric-acid-modified biochars (NBC), and three dosages were used for each modifier. The pristine and modified biochars were characterized with scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy. The biochar properties such as pH, specific surface area (SSA), and elemental contents were measured. In addition, the technique for order preference by similarity to ideal solution (TOPSIS) model based on entropy weight was used to evaluate the application potential of the biochars in alkaline soils. The FTIR spectra showed that modification with the five acidic materials, MSG wastewater in particular, resulted in more oxygen-containing functional groups such as O-H, C=O, and C-O on the biochar surface. In addition, acid modification greatly decreased the pH: phosphoric acid modification significantly decreased the pH of cotton straw biochar by 5.71–7.88 units. For the same modifier, a higher dosage (i.e., a smaller biochar:modifier ratio) led to a larger decrease in the pH of cotton straw biochar. The magnitudes of increase in total soluble salt content followed the general order of CBCs > PBCs > WBCs > NBCs > MBCs. The SSA, average pore diameter, and total pore volume of biochar were changed as well. Modification using wood vinegar and MSG wastewater significantly decreased the SSA of cotton straw biochar by 15.58–16.24 m2 g−1 (82.7–86.2%) and 15.87–16.80 m2 g−1 (84.2–89.2%), respectively, whereas modification using citric acid and nitric acid significantly increased the SSA of cotton straw biochar by 4.51–4.66 m2 g−1 (23.9–24.7%) and 0.55–54.21 m2 g−1 (2.9–287.7%). The evaluation based on entropy weight TOPSIS model suggested that the MBCs have the highest potential for application in alkaline soils. This study presents a theoretical basis for evaluation of biochar application potential, demonstrates a way of improving biochar application potential, and provides a support for beneficial utilization of agricultural and industrial wastes such as cotton straw, wood vinegar, and MSG wastewater. [ABSTRACT FROM AUTHOR]

The discharge of phosphorus from rural wastewater causes eutrophication, so phosphorus removal is regarded as an important part of water treatment. In this study, corn biochar (BC) was prepared at pyrolysis temperature of 450 °C, and then Al-Fe dual-decorated biochar (AFBC) was obtained through a two-step modification method (AlCl3 immersion before FeCl3 immersion) on the base of BC. The characterization results showed that Fe and Al were decorated on corn biochar in the form of FeOOH, Fe2O3, and AlOOH. Compared with Al/Fe mono-decorated biochar (ABC/FBC), AFBC exhibited superior phosphate removal performance in a wide pH range (pH 4.0–11.0). The adsorption behavior of AFBC was a spontaneous exothermic process, and conformed to the Langmuir and pseudo-second-order kinetic models. The adsorption mechanism was dominated by the electrostatic attraction and coordination between metal (hydrogen) oxide on biochar surface and phosphate. In the dynamic adsorption-desorption experiment, AFBC could reduce total phosphorus (TP) from 5.54 mg/L to 0.5 mg/L within 40 BV of actual rural wastewater. In addition, using phosphate-loaded AFBC as a soil conditioner promoted the growth of ryegrass, and it also provided an effective method to achieve bio-waste resource utilization and phosphorus reuse. [ABSTRACT FROM AUTHOR]

A composite rapid soil stabilizer (CRSS) is used to rapidly solidify sludge, endowing it with characteristics of fast setting, fast hardening, and high strength. The effects of freeze–thaw (FT) cycles, CRSS content, and moisture condition of the sample on physical and mechanical properties of the solidified sludge were studied through FT cycle tests, and the microscopic evolution mechanism during FT cycles was analyzed. The research results showed that with the increase of FT cycles, the mass of solidified sludge gradually increased, and the unconfined compressive strength (UCS) first increased and then decreased. With the increase in CRSS content, the appearance of the sample was more complete, and final losses in the mass and strength were smaller. After 25 FT cycles, the DR20 sample lost only 0.33% in mass and only 6% in strength. The moisture condition of the samples before FT cycles had a significant effect on the durability against FT cycles, and increasing the content of CRSS could offset the FT erosion caused by high moisture content. After 25 FT cycles, the number of pores in the sample, the most probable pore size, and the cumulative pore volume increased. Macroscopic and microscopic analyses revealed the microscopic evolution mechanism, especially the strength evolution mechanism, of the solidified sludge resistance to FT cycles. Thus, CRSS-solidified sludge exhibits good durability against FT cycles, which lays a theoretical foundation for its application. [ABSTRACT FROM AUTHOR]

Constructing on soft clay entails engineering challenges, such as significant volumetric changes; hence, stabilizing such problematic soil is essential. Since using lime in stabilizing soil is not recommended in some regions (e.g., Manitoba, Canada) due to some environmental concerns, there is a pressing need to explore suitable alternatives. This study investigates the efficiency of stabilizing soft clay using nano-modified cementitious binders (cement, slag, and nano-silica), reinforced with a new class of fibers (basalt fiber pellets). The mechanical and durability properties of the mixtures have been tested in terms of California bearing ratio, unconsolidated–undrained triaxial stresses, and freezing–thawing resistance. Thermogravimetry and scanning electron microscope analyses were performed to interpret the bulk trends. The results showed significant improvement for soft clay specimens stabilized with the nano-modified cementitious binders and reinforced with the pellets. This demonstrates the potential of the proposed reinforced binders for field applications involving the stabilization of soft soils. [ABSTRACT FROM AUTHOR]

The use of different marine residues found in the great biodiversity of the Peruvian coast, such as crushed mollusk shells or fan shells, can be used as mechanical stabilizers for clay soils due to a change in granulometry. In this article, we reviewed 70 research studies indexed in different databases such as Scopus, Scielo, Ebsco, Proquest, Springer Link, and ScienceDirect, whose publication has not exceeded seven years, with the objective of carrying out a systematic review of the use, effect and influence of marine debris as soil stabilizers. For this purpose, the analyses of the mechanical and also physical properties of such mixtures in different marine debris were reviewed compared to the various types of stabilizers currently used. These evaluated results indicate, that the Pacific razor clam shell offers a lower bearing capacity compared to the fan shell when stabilizing clayey soil. However, the shredded output of both types of marine debris can meet the need for clay subgrade stabilization. Based on the review, it was determined that the addition of different types of shredded marine debris reduces water absorption by capillarity, increasing the resistance and bearing capacity of the soil. [ABSTRACT FROM AUTHOR]

Soil plays a vital role in agriculture by providing essential nutrients, water, and support for crop growth. Therefore, the maintenance of healthy soil is imperative for the sustainability of agriculture and the assurance of food security. However, soil quality has been undermined by a range of factors, encompassing adverse environmental conditions, the impact of climate change, and inappropriate human activities. To address these issues, soil conditioners have been used to remedy soil quality. Alginate, a polysaccharide derived from brown algae, emerges as a promising soil conditioner due to its attributes of being biodegradable, non-toxic, cost-effective, easy to handle, and capable of forming gels with ease. When employed as soil conditioners, both alginate and its derivatives have demonstrated the capacity to enhance water retention in soil, augment nutrient availability, improve soil structure, and offer effective mulch films. This review aims to provide a comprehensive discussion on the utilization of alginate as a soil conditioner, covering alginate's properties, mechanisms of action, and diverse applications to enhancing soil quality and agricultural productivity. [ABSTRACT FROM AUTHOR]

The construction of infrastructure in coastal areas requires stabilizers to improve the characteristics of weak cohesionless geomaterials. Ordinary portland cement (OPC) is typically used to improve these geomaterials and provide a reliable foundation for infrastructure. However, the production of OPC is energy-intensive and has a high carbon footprint. Recently, geopolymers (GPs) have received attention as a sustainable alternative to OPC due to their low carbon footprint and ability to provide good mechanical properties. Their low carbon footprint is mainly attributed to the feasibility of using various waste and local materials such as fly ash (FA) and calcined clays for synthesizing GP. This study focused on investigating the effectiveness of metakaolin-based GPs as a stabilizer for cohesionless soils that are typically found in coastal areas. Its effectiveness was evaluated through unconfined compressive strength (UCS) and resilient modulus (MR) obtained from repeated load triaxial (RLT) tests. In addition, scanning electron microscopy (SEM) and magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy were conducted to characterize the structure of the stabilized cohesiveness soils. The strength test results showed that the addition of 20 wt.% GP was effective in improving the UCS of cohesionless soils over 115 times after 3-day curing. The RLT test indicated that treated specimens with 20 wt.% GP had similar resilient moduli as soil samples treated with 4 wt.% OPC. Micro-characterization tests confirmed that the continuous network of GP gels significantly improved the UCS of GP-treated soils. Therefore, this study has shown that GPs are an effective and eco-friendly solution for improving the cohesionless geomaterials common in coastal areas. [ABSTRACT FROM AUTHOR]

There has been an inclination towards using sustainable and environmentally friendly soil stabilizers to reduce the carbon footprint resulting from the production process of ordinary Portland cement. Polymers soil stabilizers have proven to be effective towards improving the strength of marginal soil. Despite this significant improvement, certain polymers are susceptible to the action of wetting, which results in a loss in strength. Thus, this study aims to investigate the mechanical properties and the durability of polymer-modified dune sand. Poly(vinylidene fluoride) (PVDF) polymer was used as the soil stabilizer in varying concentrations of 3, 6, 9, and 12%. The efficacy of the polymer was evaluated by conducting unconfined compressive strength (UCS) and direct shear tests. The durability test was divided into two categories: constant soaking and cyclic wetting–drying. Changes in the morphology of the sand as a result of polymer inclusion were investigated by scanning electron microscopy (SEM). The result showed that the UCS, shear strength and cohesion increased with polymer concentrations, while the frictional angle did not change significantly. The polymer-modified sand specimens lost about 60–75% of their strength after being submerged in water for 7–21 days. However, there was no reduction in strength for specimens subjected to 3 and 7 wetting–drying cycles. The action of drying following each wetting cycle reactivated the bond properties of the PVDF polymer. SEM confirmed the presence of the polymer links between the sand grains after constantly soaking. The loss of strength, in this case, can be linked to the presence of water molecules within the structure of the polymer-sand matrix. In conclusion, the PVDF polymer exhibits potential as an effective stabilizer against water susceptibility and elevated temperature. [ABSTRACT FROM AUTHOR]

In response to climate change, wood pellets have been increasingly utilized as a sustainable energy source. However, their growing utilization increases the production of wood pellet fly ash (WA) by-products, necessitating alternative recycling technologies due to a shortage of discharging landfills. Thus, this research seeks to utilize WA by developing a new sustainable construction material, called wood pellet fly ash blended binder (WABB), and to validate its stabilizing performance in natural soils, namely weathered granite soil (WS). WABB is made from 50% WA, 30% ground granulated blast-furnace slag (GGBS), and 20% cement by dry mass. WS was mixed with 5%, 15%, and 25% WABB and was tested for a series of unconfined compressive strength (qu), pH, and suction tests at 3, 7, 14, and 28 days. For the microstructural analyses, XRD, SEM, and EDS were employed. As the WABB dosage rate increased, the average qu increased by 1.88 to 11.77, which was higher than that of compacted WS without any binder. Newly cementitious minerals were also confirmed. These results suggest that the effects of the combined hydration mechanism of WABB are due to cement's role in facilitating early strength development, GGBS's latent hydraulic properties, and WA's capacity to stimulate the alkaline components of WABB and soil grains. Thus, this research validates a new sustainable binder, WABB, as a potential alternative to conventional soil stabilizers. [ABSTRACT FROM AUTHOR]

This article presents an experimental study to analyze the mechanical properties of a soil stabilized with ordinary Portland cement (OPC) under a sustainable approach consisting of a significant substitution of OPC for sugarcane bagasse ash (SCBA) to reduce the quantity of cement used in the stabilization, reaching the necessary mechanical requirements for its use as a subgrade layer. Soil specimens were elaborated with 3%, 5%, and 7% OPC as a stabilizing agent by weight of the soil. These mixtures were then partially substituted with 25%, 50%, and 75% SCBA, with these percentages being by weight of the stabilizer (OPC). Compaction, compressive strength, and California bearing ratio (CBR) tests were performed to evaluate the mechanical properties of the specimens. The results indicate that a 25% substitution of OPC by SCBA shows a similar performance to the mixture with only Portland cement, so a reduction in OPC use can be made. Further, with a substitution of 100% OPC by SCBA, the CBR of natural soil without stabilizers is improved. [ABSTRACT FROM AUTHOR]

The sustainable management of coffee plants can enhance crop growth and yield, improving the plant environment due to the increase in soil's water storage, leading to a healthier and more productive crop. This study aimed to evaluate the combined effect of soil coverings, soil conditioners, and controlled-release fertilizer on the growth and yield of coffee plants in the first productive biennium. The factors under study were arranged in a 3 × 2 × 5 split plot-factorial experiment, totaling 30 treatments, in a randomized block design with three replications. In the plots, three soil managements were randomized (soil cover in the rows with polyethylene film, soil cover with the ecological management of Urochloa decumbens, and conventional management of spontaneous vegetation). In the subplots, two types of fertilizers used in the fertilization of coffee plants (conventional and controlled-release fertilizer) were tested. In the main plot were tried four soil conditioners (coffee husk, agricultural gypsum, water-retaining polymer, organic compound) and the control without conditioner. Using Urochloa decumbens + coffee husk/organic compound + controlled-release fertilizers resulted in higher growth and yield of the coffee plants. So, sustainable techniques resulted in better plant nutrition and ensured increasing yields, without the effect of bienniality. [ABSTRACT FROM AUTHOR]

Organic farming has emerged as a sustainable approach for increasing crop production while maintaining soil fertility. This eco-friendly practice relies on the use of various living microbes such as Rhizobia, arbuscular mycorrhiza fungi (AMF) and partially or fully decomposed biological materials like manure, compost, litter, coir, moss, and similar products used as soil supplements and/or conditioners for augmenting soil fertility. The present study was designed to evaluate the effect of these amendments on soil physico-chemical characteristics, and on germination and growth of marigold (Tagetes erecta) seedlings raised on these soils. The experiment was carried out in pots filled with garden soil amended with compost, moss, coir and NPK while un-amended garden soil served as control. Analysis of soil samples with organic materials show a slight change toward basic pH while inorganic fertilizer made the soil acidic. All the amendments led to increase in electrical conductivity while modulation of soil texture resulted in change in percolation rate. Amendments also resulted in changes in the soil nutrient content (organic C, N, P, K, Mg, Cu and Zn). However, coir and moss amendments did not bring about much change in nutrient status of the soil. There were notable changes in growth of marigold expressed in increased fresh weight, root length, shoot length as well number of nodes and number of leaves in amended soils. The study indicates that though coir and moss did not bring much change in nutrient status of soil but they altered the particle size for improved percolation. [ABSTRACT FROM AUTHOR]

A widespread method of sewage sludge disposal is still simple storage in sludge lagoons. Subsequent thermal utilization is hardly possible because sludge properties change over time and energy content is reduced. Use as a soil conditioner in agriculture or landscaping is usually not possible due to high heavy metal contents. This paper describes a method in which a 10-year-old accumulated sewage sludge can be utilized as technical soil by mixing it with pyrolized fresh sewage sludge. For this purpose, physicochemical and toxicological characteristics of sewage sludge of different storage periods were identified, processes of thermal destruction of sewage sludge analyzed, toxicological characteristics of solid products of thermal sludge treatment determined, and the possibility of using the sewage sludge–pyrolysate mixture as technical soil was assessed. Results show that the gross calorific value of fresh and one-year stored sewage sludge is with approx. 15,000 kJ/kg dry basis sufficient to produce pyrolysate autothermally. It is also shown that when the pyrolysis residue is mixed with fresh or 1-year old sewage sludge, heavy metals can be immobilized and thus the leaching of heavy metals significantly reduced by up to 75%. The method described can thus be a possible option for recycling accumulated sewage sludge. [ABSTRACT FROM AUTHOR]