Soil Mixing Research Articles

Ecological and microbiological monitoring of soils in places of mass recreation

Introduction. There are presented results of a comprehensive ecological and microbiological assessment of soils located in the central part of the recreational zone of the city of Petrozavodsk, located in the middle taiga area. The study of chemical and microbiological properties of the soils of the park zone in the spatio-temporal aspect is of great importance for assessing the current state of soils and the trend of their development in conditions of anthropogenic impact, and can be the basis for urban ecological monitoring also. 
 The aim of the study is ecological and microbiological monitoring of soils in places of mass recreation of the urban population (Petrozavodsk).
 Materials and methods. The object of the study was the soils of the plots located in the central part of the city. The soils located on the territory of the Kivach Nature Reserve were selected as a control. The acid-base properties of soils, the content of heavy metals, as well as the state of the microbiotic component of soils were evaluated. Based on the data on the content of heavy metals, the degree of soil contamination with heavy metals was determined. 
 Results. Based on the data of a comprehensive study, the current state of the soils of the recreational zone of Petrozavodsk has been established. The comparative analysis of changes in chemical and microbiological properties, as well as data on the soil pollution coefficient in the space-time interval revealed a decrease in anthropogenic impact on soils. Changing the category of soil pollution is an important tool of environmental protection measures carried out on the territory of the city.
 Limitations. Work in the field of urban-ecological research is complicated by the lack of local regulatory documents that substantiate the hygienic standards for chemicals polluting the soil; limited monitoring points and work with mixed soil samples, which creates a problem of representativeness of the obtained data. 
 Conclusion. The favourable conditions for the formation of soils in the park zone affect on their soil properties, which generally meet the hygienic requirements imposed on them. The established higher indicators of the soil pollution coefficient in certain areas indicate a high anthropogenic pressure in the past, are the basis for continuing research, the need for periodic work, as well as expanding the range of soil indicators used for early diagnosis of their degradation.

Strength, leaching characteristics and microstructure of CGF+P all-solid-waste binder solidification/stabilization Cu(Ⅱ) contaminated soil

Utilizing solid waste-based binder to solidify/stabilize (S/S) heavy metal contaminated soils is a sustainable approach. This paper implemented microscopic tests on Cu(II)-doped paste and macro-microscopic tests on S/S Cu(II) contaminated pure clay-particles soil (P-CS), pure silt-particles soil (P-ST), pure sand-particles soil (P-SD), and their mixed soil (CSSM), respectively, with CGF+P all-solid-waste binders (abbreviated as CGF+P binders) composed of calcium carbide residue (CCR), ground granulated blast furnace slag (GGBS), fly ash (FA), and phosphogypsum (PG). The results showed that the clay-minerals in soil determine the S/S efficiency, and Cu(II) threshold content exist in the presence of clay-minerals and absent without clay-minerals. The strength of P-CS and CSSM containing clay-minerals first increased and then decreased with the increase of Cu(II) content, while the leached Cu(Ⅱ) were lower than 2 mg/kg. The strength of P-ST and P-SD without clay-minerals decreased gradually, and the leached Cu(Ⅱ) concentration far higher than 2 mg/kg. Cu(II) ions are immobilized by CGF+P paste and clay-minerals in soil. The S/S mechanism of Cu(II) by CGF+P binders rely on precipitation, adsorption, encapsulation, chemical compound, and ion exchange, and the immobilized mechanism of Cu(II) by clay-minerals through electrostatic attraction, ion exchange, and physical adsorption. However, the binder paste and clay-minerals have the immobilization capacity on Cu(II) ions, is related to the component of the binder and the type of clay-minerals, respectively. The findings provided useful reference for the design and development of solid waste-based binders suitable for S/S heavy metal contaminated soils.

Quantifying and assessing nitrogen sources and transport in a megacity water supply watershed: Insights for effective non-point source pollution management with mixSIAR and SWAT models

The expansion and intensification of human activities have resulted in excessive nitrogen (N) in rivers, causing worldwide concern. To effectively manage agricultural non-point source pollution and ensure a safe drinking water supply in watersheds, it is crucial to trace and quantify the primary sources and spatial distribution patterns of N. In response to the challenge of unclear sources and agricultural non-point source pollution, this study utilised the Bayesian isotope mixing model and Soil and Water Assessment Toolmodel to identify the dominant nitrate sources and transformation processes. These models were employed to quantify N retention by the mainstream and tributaries in the Bai River Basin, which directly impacts the safety of drinking water in Beijing. Total N (TN) concentrations in the Yunzhou Reservoir (4.22 ± 0.04 mg.L˗1) and Miyun Reservoir (2.88 ± 0.62 mg.L˗1) inlets in autumn and winter were V class (2 mg.L˗1) category as per GB 3838–2002 standards. This implies higher risks of eutrophication and algal blooms exceeding the standards at individual points and seasons in the Bai River. Fertilisers were the main nitrate source in the Bai River Basin, contributing 44.6% during the dry season and 62.9% during the wet season, suggesting that nitrate is more susceptible to leaching and runoff during rainy periods. Rainfall was not a major contributor, with only 3.2% and 2.9% originating from the Hebei and Beijing areas of the Bai River, respectively. Annually, the Bai River Basin exports loads of approximately 629.3 t.a˗1 of TN and 433.7 t.a˗1 of organic N (Org-N) from the Bai River Basin land to the river. The TN and Org-N loads at the final destination in the Miyun Reservoir were 521.3 t.a˗1 and 100.3 t.a˗1, respectively. Of the exported TN and Org-N, 17.16% and 76.87%, respectively, were retained in the river network. Consequently, N transformation occurred in the Bai River, with nitrification–denitrification being particularly dominant. Nitrification was more evident in the nitrate-enriched river.

Soil organic carbon and nitrogen reduction through cattle-path induced erosion in montane grasslands, KwaZulu-Natal, South Africa

The impact of daily cattle migration from homesteads to higher altitude pastures creates severe erosion in the montane grasslands of the predominantly subsistence agricultural rural communities of KwaZulu-Natal, Drakensberg, South Africa. This study quantifies the impact of a degraded cattle path at up, mid and downslope positions on SOC and N distribution in the soil profile and within the soil aggregates. An attempt to evaluate sites of erosion and deposition using excess lead-210 (210Pbex) to support our findings was conducted. On average, the degraded cattle path reduced SOC and N in the bulk soil (by 3–4 times, respectively) and was associated with 53% reduction in aggregate stability and a 14% increase in soil bulk density over the non-degraded reference site. These results reflect the loss of vegetation cover (correlated positively to SOC and N (r ≈ 0.94)), which were triggered by cattle grazing and trampling leading to top-soil loss. Cattle hoofs damage the grass and breakdown soil aggregates, exposing the fertile topsoil particles to detachment and consequential transportation via rill and sheet erosion. This is supported by the loss of 210Pbex in the topsoil of the degraded slope positions relative to the reference site. Consistent down core mixing of 210Pbex activity in degraded slope sites supports evidence of cattle mediated soil mixing. Our findings highlight the accelerated land degradation that results from uncontrolled grazing and movement of cattle on sloping lands in the Okhombe Valley. Developing an integrated management strategy co-led by local communities to develop proactive participatory sustainable land use practices is critical for long-term landscape maintenance and recovery in the region.

Stabilisation of estuarine sediments with an alkali-activated cement for deep soil mixing applications

In this work, an alternative alkali-activated cement (AAC) made of ladle slag precursor mixed with sodium hydroxide and sodium silicate has been developed to enhance the bearing capacity of estuarine soils in coastal conditions via deep soil mixing (DSM). The AAC was optimized to use a low reactivity precursor (ladle slag) and to deal with a contaminated high-water content natural sediment cured under water. The material performance was analysed by comparison to a mixture made with Portland cement and cured in the same conditions. Flexural and unconfined compressive strength tests as well as seismic waves measurements after 3-, 7-, 14- and 28-d curing were performed to obtain a relationship between elastic stiffness and strength with curing time for both mixtures. Remarkably, the AAC mix demonstrated superior strength results, exhibiting almost double flexural and compressive strengths after 28 d compared to the Portland cement mix. The AAC mix also showed a higher rate of stiffness increase than the Portland cement mix, which has a higher initial stiffness at young ages but lower stiffness evolution. Leachate analysis confirmed that the proposed AAC could effectively immobilise any contaminants from soil or precursors. The effect of curing under stress was analysed in triaxial compression tests and found to be insignificant, indicating that laboratory data obtained without stress curing can represent the material's behaviour in a DSM column, which will cure under the weight of the column.

The Effect of Self-Healing Microorganism-Encapsulating Concrete on Enhancing Concrete Compressive Strength

Investigating microbially induced calcite precipitation (MICP) of concrete in bacillus and the durability of crack-filled repair structures were the goals of this work. The purpose of this study was to investigate the self-healing effect of concrete in bacillus and the strength of crack-filled repair structures. The characteristics of calcium carbonate particles and the performance of those penetrating cement were observed using optical microscopy. The cement block pressure test was used to study the factors affecting the healing rate of concrete materials mixed with microorganisms. The results showed that the microorganisms had good microscopic morphology. Microbial mixed soil had good compression resistance, and the ability to play a repairing role in mixed soil composite materials was that organisms could be attached to the concrete tightly. The main fracture behavior of the mixed soil was a small-hole rupture, while no macroscopic damage or large-pore ruptures were observed in the mixed soil matrix. Sporosarcina pasteurii exhibited better potential than Bacillus subtilis and could act as a self-healing agent in the concrete. The test results proved that S. pasteurii produced a colloidal adhesive to fill and repair cracks. The study designed concrete of different densities to create cubes having different compressive strengths, water permeability, and water absorption to further observe the ability of Bacillus to fill the cracks and prevent water penetration. The results showed a 60 % increase in the compressive strength of the coarse aggregate experimental sample and a 36 % decrease in the compressive strength of the fine aggregate experimental sample, relative to the same properties in the control sterile sample. Samples indicating the use of bacteria in the aggregate were denser and less porous. It was proven that the use of microorganisms could achieve self-healing ability in concrete materials, fill up pores, and establish functional effects.

The Effect of Mycorrhiza Inoculation and Organic Fertilization on some Growth and Flowering Qualities of the Chrysanthemum Plant Calendula officinalis L.

The experiment was carried out in the wooden canopy - Faculty of Agriculture-Tikrit University - during the agricultural season 2020-2021 in plastic pots and planted Chrysanthemum seedlings, the seeds of which were grown in Cork dishes on 10/1/2020, the seedlings were transferred to plastic pots with a diameter of 14 cm when 5-4 of the real leaves were formed by 18 repeated treatments three times to make 54 experimental units using the following transactions : 1-inoculation with mycorrhiza fungus of the type Glomus mosseae at two levels (with and without inoculation). 2-using two-level compost(with and without compost) manufactured from printing papers in a ratio of (1: 3), i.e. 3 paper compost and 1 soil, Also an artificial ptomose was used with a ratio of (2-1). And mixed soils (for comparison treatment). 3-use chemical fertilizer with three levels (no fertilizer, half recommendation, full recommendation). The results showed that inoculation with mycorrhiza fungi led to a significant increase in the dry weight rate.

Study of the Effect Developed Chisel Plow on some Soil Properties in Heavy, Clay-Textured Soils

A field experiment conducted in the fields of the College of Agriculture - University of Basrah, Karmat Campus, according to the randomized complete block design (RCBD), to study the effect of height sweeps shank in back row with the developed chisel plow (10 and 20 cm), with three depths (15, 25 and 35 cm) and three lateral distances (20, 25 and 30 cm), on the field performance indicators where the mean weighted diameter, bulk density and total soil porosity are present. In mixed loamy soil with a density of (1.25) g cm3 and a moisture content of (15.17)%, the experiment was designed according to the randomized complete block design (RCBD). The results showed that the improved chisel plow was significantly superior to the normal chisel plow by giving it the lowest mean weighted diameter ratio (higher fracturing), the least density, and the highest porosity, as the weighted diameter decreased significantly when both the lateral distance and the height of sweeps shank increased. The values of the mean weighted diameter (increased smoothing) decreased at a height of 20 cm of sweeps shank, and increased with the increase in lateral distance and depth. Bulk density values decreased at 10 cm height for the rear sweeps shank, and increased with increasing the lateral distance and the depth of plowing. The porosity increased at the height of the sweeps shank 10 cm and the depth of tillage 15 cm, and there was no significant effect of the lateral distance in the porosity.

The Effect of Inoculation with Mycorrhiza Fungi and Organic Fertilization on the Content of Plant Nutrient-Absorbing and Heavy Elements of Chrysanthemum Calendula Officinalis L.

The experiment was carried out in the wooden canopy of the Department of horticulture and garden Engineering - Faculty of Agriculture-Tikrit University - during the agricultural season 2020-2021 in plastic pots and planting Chrysanthemum seedlings, the seeds of which were planted in Cork dishes on 10/1/2020, transferring seedlings to plastic pots with a diameter of 14 cm. When forming from 5-4 real leaves. 1-Use Two-level compost (with and without compost) manufactured from printing papers in a ratio of (1: 3), i.e. 3 paper compost and 1 soil. It will be served by an industrial batmoos with a ratio of (2-1). And mixed soil for (Control). 2-inoculation with mycorrhiza fungus of the type Glomus mosseae at two levels (with and without inoculation. 3-use chemical fertilizer with three levels (without fertilizer, half recommendation and full recommendation) It produces 18 transactions that are repeated three times to make 54 trial units. The results showed that inoculation with mycorrhiza fungi led to a significant increase in the dry weight rate and the relative chlorophyll content of the Chrysanthemum plant, the favorable increase for pollinated plants over non-pollinated plants was (32.3, 7 %) the increase in the absorbing elements nitrogen, phosphorus and potassium (37, 37, 33.3 %) respectively, while inoculation with mycorrhiza fungi reduced the absorption of heavy elements by (45.7,60,40,16.6 %) for the elements zinc, lead, cadmium and arsenic respectively, The results showed the importance of inoculation with mycorrhiza fungi in increasing plant growth by increasing the efficiency of absorption of plant nutrients and reducing the absorption of heavy elements.

The Effect of Biochar and Extract of Organic Fertilizer on the and Yield of Wheat (Triticum aestivum L.)

A field experiment was conducted at the second research station of the Faculty of Agriculture at Muthanna University in mixed soil to study the impact of different levels of biochar and organic fertilizer extract in some growth qualities and the yield of the spelt (Triticum aesativum. L) (plant height and leaf area, biomass, grain yeild, weight of 1000 grain, harvest index). The experiment involved the use of four levels of bio-coal (A0,0%) (A1,1.5%) (A2,2%) (A3,2.5%) volume of biochar added on the basis of the size of the soil, and four levels of organic fertilizer extract (0.20,40,80 L) per hectare and its symbol (B0, B1, B2, B3). Compare averages by LSD test at a morale level of 0.05. The results show that there are moral differences in the addition of biochar and organic fertilizer extract and the overlap between them in plant elevation values. The results also indicate that there is a moral effect on the different levels of biochar and organic fertilizer extract and the overlap between them in the values of the science leaf area. The biochar and organic fertilizer extract and their overlap had a moral effect on the grain and biochar quotient. The results also showed a moral effect of adding biochar and organic fertilizer extract in the values of the harvest index. The results also showed that there were moral differences in the addition of biochar in the weight of 1000 grain

Evaluation of the horizontal cyclic shear stress on the enclosed soil in DSM grid-improved ground by numerical simulation

Deep soil mixing (DSM) grids are widely used as effective countermeasures against liquefaction hazards. A simplified two-dimensional, nonlinear, finite element model involving DSM grid-improved ground is proposed to investigate the shear stress responses of the enclosed soil. A numerical model with several approximations of longitudinal walls was carefully validated by a centrifuge model test. The waist-shaped depth distribution of the horizontal cyclic shear stress acting on the enclosed soil (i.e., the “waist effect”) was revealed and well explained according to the characteristics of dynamic soil-grid interactions. Attention should be given to the increasing shear load sustained by the underlain layer, which may lead to an unexpected failure. A mathematical model for the shear stress reduction ratio was proposed based on a comprehensive numerical parametric analysis considering varying geometry and shear modulus of the DSM grid with a reasonable range. The proposed evaluation method, along with conventional liquefaction-triggering analysis, can be utilized for the seismic design of DSM grids in liquefaction mitigation. The previous design methods without considering the “waist effect” underestimate the overall horizontal cyclic shear stress acting on enclosed soil.

Assessing deep soil mixing for excavation support in Sabkha soils: a numerical study

AbstractExcavation in Sabkha soils, found in coastal regions of Saudi Arabia, presents complex challenges in construction due to their unique geotechnical characteristics. These soils are known for their high compressibility, collapsibility, and variable sediment deposition, rendition them unsuitable for excavation without adequate support systems. As urbanization and industrial activities continue to expand into these areas, the demand for effective excavation support systems becomes gradually critical. This study investigates the feasibility of employing Deep Soil Mixing (DSM) as an excavation support system in Sabkha soils. Utilizing finite element analysis through PLAXIS 3D software, the behaviour of DSM walls in Sabkha soil under various conditions is rigorously simulated. The findings of this research establish that DSM walls can serve as an efficient excavation support system in Sabkha soils, provided that crucial factors, particularly excavation depth, are considered during the design phase. The study demonstrates that properly designed DSM walls, in combination with appropriate anchoring methods, can substantially reduce horizontal displacement and bending moments, ensuring the stability of excavations in Sabkha soils. The research highlights the need for further investigations into the cost-effectiveness of DSM walls in comparison to other excavation support options to evaluate the economic feasibility of using DSM in Sabkha soil applications.

Numerical analysis of a monitored piled-supported embankment of an airport runway

This paper presents a 3D finite element analysis of deep soil mixing column-supported embankments (CSEs) with a geosynthetic platform. The numerical model simulated the CSE for the expansion (≈1.0 km) of the existing runway at the Salgado Filho International Airport, in the city of Porto Alegre. The numerical model using Abaqus software was calibrated by comparing numerical calculations with good quality instrumentation data. Deep Soil Mixing (DSM) columns were used to improve the soil foundation. A novel approach to modeling the geosynthetic is also presented based on the mechanical properties of this material. The load transfer mechanisms and deformation of the column-supported embankments were analyzed by means of numerical and field results. Additional aspects such as the critical height and the pattern of vertical stress distribution in the columns and embankment as well as the stress distribution in the geosynthetic reinforcement were also investigated. The numerical model reproduces the vertical stress measured by the total stress cells installed above the columns and between the columns. The numerical model shows that the soil reaction of the thick compacted layer used as a work platform reduced the arching and membrane effect in the embankment.

Solar-induced chlorophyll fluorescence extraction based on heterogeneous light distribution for improving in-situ chlorophyll content estimation

Accurate estimation of leaf chlorophyll content (LCC) in field for wheat crops is important to provide guidance for precision management. Solar-induced chlorophyll fluorescence (SIF) extraction based on hyperspectral imaging is an effective tool for LCC estimation, which is because SIF is a signal directly and intrinsically related to photosynthetic activity of crops. However, soil background and structural difference always lead to mixing of soil, shadowed and sunlit canopy components, and heterogeneous light distribution among canopy, which increase the complexity of SIF extraction and reduce the LCC estimation accuracy. The purpose of this study is to propose an accurate SIF extraction method by eliminating above challenges to improve the LCC estimation accuracy. Hyperspectral image and LCC measurements were conducted at the jointing and heading stages of wheat crops. Firstly, to eliminate the effect of soil background, two image segmentation methods, excess green index (ExG) and optimized soil-adjusted vegetation index (OSAVI), are compared to extract the crop region. Secondly, to reduce the canopy structure effect, light distribution condition is evaluated by the brightness, which is extracted from intensity component of hue-saturation-intensity color space. Then K-means clustering based on the brightness distribution is utilized to divide the segmented crop region further into shadowed and sunlit regions. Finally, SIF was extracted based on the Fraunhofer line discriminator method at 687 and 761 nm, and was modified by normalization of brightness to reduce the influence of heterogeneous light distribution. The performance of random forest regression models, which are built by extracting SIF based on raw image, segmented crop by ExG segmentation, segmented crop by OSAVI segmentation, and shadowed and sunlit regions, respectively, is compared. Results show the estimation accuracy of the models increases when image segmentation is performed (determination coefficient of prediction set (RP2) = 0.37 for ExG segmentation; RP2 = 0.47 for OSAVI segmentation) compared with raw image (RP2 = 0.30). Moreover, shadowed region clustering based on brightness was optimal region for SIF extraction (RP2 = 0.54) compared with the sunlit region (RP2 = 0.27). The modified SIF at shadowed regions, normalized by the brightness of crops to reduce the effect of heterogeneous light distribution, yields the highest relationship with LCC (RP2 = 0.79), which outperforms SIF normalized by the absorbed photosynthetically active radiation (APAR). The reason is that brightness is more related to LAI, a parameter representing canopy structure, than APAR. It suggests that OSAVI segmentation for soil background effect elimination and SIF extraction considering canopy structure and heterogeneous light distribution facilitate the improvement of LCC estimation accuracy for high-throughput phenotyping in field.

Environmental Life Cycle Assessment of a Novel Hemp-Based Building Material.

The global construction sector contributes a significant share of total greenhouse gas (GHG) emissions. In Australia, infrastructure activity alone generates 18% of the GHG emissions. The use of low-embodied carbon building materials is crucial to decarbonise the construction sector and fulfil national and international climate goals. Industrial hemp (Cannabis sativa L.) is a promising feedstock for low-carbon construction materials because of its carbon sequestration capacity, fast-growing cycles, and technical functionality comparable to traditional materials. This study utilised the life cycle assessment (LCA) guideline ISO 14040:2006 to estimate the carbon footprint (CF) of hemp-based building materials in Western Australia capturing region-specific variations in terms of inputs, soil, productivity, and energy mix. The functional unit was 1 m2 of a hemp-based board, and the system boundary was cradle-to-gate, i.e., pre-farm, on-farm, and post-farm activities. The CF of 1 m2 of hemp-based board was estimated to be -2.302 kg CO2 eq. Electricity from the public grid for bio-based binder production during the post-farm stage was the main contributor to total CO2 eq emissions (26%), followed by urea production (14%) during the pre-farm stage. Overall, the use of electricity from the public grid during the post-farm stage accounted for 45% of total emissions. Sensitivity analysis showed that the CF of hemp-based boards was highly sensitive to the source of energy; i.e., total replacement of the public grid by solar power decreased the CF by 164% (-2.30 to -6.07 kg CO2 eq). The results suggested that hemp-based boards exhibit lower embodied GHG emissions compared to traditional materials, such as gypsum plasterboards.

Mineralization mechanism of organic carbon in maize rhizosphere soil of soft rock and sand mixed soil under different fertilization modes.

This article endeavors to investigate the influence of various fertilization methods on the characteristics of rhizosphere soil and organic carbon mineralization in the mixed soil of Mu Us Sandy land under maize cultivation, with the objective of laying the groundwork for low-carbon agriculture and the development of high-quality farmland. The research focuses on soft rock and sand composite soil with a 1:2 ratio, and it comprises four treatments: no fertilization (CK), only chemical fertilization (CF), only cattle manure application (MF), and only oil residue application (DF). The findings revealed that the use of organic fertilizer substantially elevated nutrient content and enzyme activity in the maize rhizosphere soil. Furthermore, it had a notable influence on both soil aggregate diameter and stability. Specifically, the DF treatment led to a significant increase in both soil aggregate diameter and stability. The mineralization rate of organic carbon in the maize rhizosphere soil could be categorized into two distinct phases: a rapid initial decline followed by a slower release. By the end of the incubation period, the cumulative mineralization of organic carbon in the MF, DF, and CF treatments showed a significant increase of 119.87%, 57.57%, and 24.15%, respectively, in comparison to the CK treatment. Additionally, the mineralization rate constants of the DF and MF treatments experienced a substantial rise, with increments of 23.52% and 45.97%, respectively, when contrasted with the CK treatment. The bacterial phyla Actinobacteriota, Proteobacteria, Chloroflexi, Acidobacteriota, and Firmicutes were dominant in the rhizosphere soil bacterial community. Specific genera such as Nocardioides and Sphingomonas showed significant correlations with organic carbon mineralization. The application of different organic fertilizer can improve soil physical, chemical and biological properties, and promote the mineralization process of organic carbon in maize rhizosphere soil. Notably, the DF treatment exhibited the most favorable outcome, improving the overall quality of maize rhizosphere soil while incurring a minimal loss of unit organic carbon. These findings hold significant implications for optimizing field management practices and augmenting soil quality.

A preliminary report on sculptures and figurative terracottas found at the site of Vlochos, region of Karditsa, Thessaly

The existence of an ancient city at Thessalian Vlochos was first established by the discovery in 1964 of several inscribed stelai at a quarry at the site, which in turn prompted its declaration as a protected archaeological zone. A large spoil-heap with mixed soils and quarry debris had been left after the closure of the quarry, and this was examined and removed as part of the ongoing Greek-Swedish archaeological collaboration at the site. Apart from quarry debris and rubbish, the soils of the heap yielded considerable amounts of pottery and tile, and also architectural members, terracotta figurines, stelai, marble statuettes, and votives. The mixed nature of the soils made all finds ex situ, but the composition of the material provides a transect of the chronology of the site at Vlochos, as well as strong indications of cult, including evidence for the cult of the Thessalian goddess Ennodia.

Core species impact plant health by enhancing soil microbial cooperation and network complexity during community coalescence

Soil microbial communities mix and interact, a widespread phenomenon known as community coalescence. However, in the context of different coalescence degrees, the effects and potential applicability of soil mixing on plant disease resistance have not been studied. Here, we mixed soils from two habitats (healthy and diseased soils) at different mixing ratios for watermelon planting. Rhizosphere soils were collected for amplicon sequencing to study the effects of different degrees of bacterial community coalescence on plant growth and disease resistance, as well as on the characteristics, network complexity and stability of rhizosphere microbial communities. Combined with network and cohesion analyses, we found that mixing in more healthy soil reduced the plant disease index and increased biomass by improving the stability and complexity of the network; positive cohesion, reflecting degree of cooperation, was also negatively correlated with the plant disease index. The rhizosphere from healthy soils enriched the core taxa, Nitrospirillum and Singulisphaera. These core taxa were significantly associated with disease suppression and important for regulating the positive cohesion and modularity of the networks. Overall, these findings revealed that the soil bacterial community coalescence enhanced the stability and complexity of the rhizobacterial network, simultaneously core taxa enhanced microbial potential cooperation and network complexity, ultimately enhancing plant health and biomass. Our results provide insights into the understanding of microbial community coalescence as a potentially effective mechanism for improving plant microbial community function and suggest promising new tools for improving plant fitness via mixing soil microbiota.

Evaluating the Printability and Rheological and Mechanical Properties of 3D-Printed Earthen Mixes for Carbon-Neutral Buildings

This research delves into the vital aspect of adapting local soil properties for 3D printing and explores the mix design of collected earthen materials to tackle challenges in printability, shrinkage, and mechanical properties. Initially, soil samples from six local sites underwent characterization based on Atterberg’s limits, focusing on identifying the most suitable high-clay-content soil. The soil with a higher clay content was used for further study, and its clay type was determined using an X-ray diffraction (XRD) analysis, revealing the presence of 49% kaolinite, 15% nontronite, and 36% illite clay minerals. Four earthen mixes were designed by including stabilizers (i.e., hydrated lime), natural pozzolana, and degradable natural fibers (wheat straw fiber). Subsequently, the study examined their rheological properties, shrinkage behavior, compressive and flexural strength, and printability (including extrudability and buildability). The pure soil mixture excelled in printing quality and mechanical strength, but suffered from cracking and drying shrinkage due to its high nontronite clay content. The existence of 15% nontronite clay mineral in the soil resulted in significant shrinkage and extensive cracking of specimens. However, fiber incorporation effectively mitigated large cracks and reduced shrinkage to as low as 2.6%. Despite initial expectations, introducing lime and pozzolana as soil stabilizers did not improve strength, prevent shrinkage, or improve the printability of soil mixes.

Dark septate endophyte inoculation improved Pb phytoremediation of Jatropha curcas and Reutealis trisperma on gold mine tailings

This study investigated the symbiotic potential of Jatropha curcas and Reutealis trisperma with two isolates of dark septate endophyte (DSE) fungi (Cladosporium sp. and Rhyzopycnis vagum) grown on gold mine tailings media based on their ability to remediate Pb and their morphological, physiological, and anatomical changes. The targeted plants were grown for 12 weeks on different media contained mixed soil and compost, gold mine tailings, and tailing with additional charcoal. The result showed that DSE inoculation increased the height of J. curcas up to 24.1% in contaminated soil compared to control treatment without DSE. All DSE fungi were able to colonize both root plant even under gold mine tailing treatment. DSE inoculation increased chlorophyll content of both plants ranging from 11% to 33% compared to the plants without DSE. Jatropha curcas inoculated with DSE had the potential to be used as phytoremediation plant with a phytoextraction mechanism indicated by higher translocation factor (TF) value. Meanwhile, the R. trisperma was able to be used for phytoremediation categorized as phytostabilization due to lower TF values. The results of this study highlighted the possible role of the DSE symbiotic with J. curcas and R. trisperma to improve the efficiency of phytoremediation in contaminated lands.