Sand Soil Research Articles

Remotely Controlled Armed Surveillance Rover

A remotely operated ground vehicle was designed and developed for use in counter terrorism and counter-insurgency operations by the Indian Army. The Rover can traverse difficult terrain, extreme slopes, inspect suspicious objects (e.g. improvised explosive devices) with a robotic weapon with a camera(even when hidden under a bridge), and give visual feedback to an operator away at a safe distance of certain range. It can be operated using mobile and can be self-triggered when a command is given. Militaries are now equipped with various types of rovers. Rover for assistance and spy purposes are developing. This project represents an application of Rover in the military. This rover is 4-wheeled developed on a rocker-bogie mechanism. According torecent Rover developments, rovers with rocker-bogie mechanismscan glide on rough surfaces, sand, and loose soil easily. Thedegree of freedom for the rover is 4 with the ability to rotate 360°.This rover is equipped with frequency hopping which makes it ananti-hack device. This project is useful for attacking the opponentsin the war without losing our army officers. So by using thisproject we can do war without losing human life on our side.

Abrasive Wear Characteristics of 30MnB5 Steel for High-Speed Plough Tip of Agricultural Machinery in Southern Xinjiang Region

The high-speed plough tip is the core soil-touching component in southern Xinjiang field cultivation, but the interaction of the plough tip with the soil results in severe wear of the tip. The friction behaviour of sand and soil on plough tips was investigated with a homemade rotary abrasive wear tester in a one-factor multilevel test with three parameters: moisture content, velocity/rotational speed and friction distance. The objective was to study the friction behaviour of the sand soil and plough tip and analyse and characterise the wear amount, wear thickness and compressive stress distribution, three-dimensional wear morphology and microscopic wear morphology of the plough tips. The results show that with increasing speed, the wear amount changes more gently; with increasing soil water content, the soil adhesion force and lubricating water film increase so that the wear amount follows a second-order parabolic law; and with increasing friction distance, the wear amount gradually increases, and the wear rate also shows an upward trend when the plough tip is in the abrasive wear stage. The tip makes contact with the firmer soil with higher surface compressive stresses, causing the most wear. As the friction distance increases, sand particles become embedded in the contact surfaces, creating a groove effect along with spalling pits caused by fatigue wear. During the whole wear period, the groove effect is always accompanied by spalling pits appearing repeatedly. The analysis of the wear micromorphology of the plough tip shows that the number of flaking pits gradually decreases in the direction of soil movement, and the form of damage changes from impact wear to plough groove scratches. Abrasive wear interacts with corrosive wear to exacerbate plough tip wear.

Revealing the optimal strategy for tree plantations on controlling soil erosion in China: A meta-analysis

Tree plantation has increased globally, driven by a desire to supply multiple ecosystem services including soil erosion control. However, how to plant trees can more effectively mitigate soil erosion still lacks systematic investigation. Therefore, we conducted a meta-analysis consisting of 412 paired observations from 80 studies to rigorously compare the effects of tree plantations on soil erosion control across different plantation approaches in China. The results showed that plantation age and ground cover type were the primary factors influencing the efficiency of tree plantations on runoff and sediment reduction. Mature plantations (>20 years) showed more efficiency in runoff (80.9 %) and sediment (97.2 %) reduction than young plantations (<10 years). The benefit of tree plantations with grass cover on runoff reduction was 70 %, while the capacity of plantations without ground cover was not significant. In addition, tree plantations in areas with steep slope, low mean annual precipitation, high soil sand content, and low soil organic carbon had better benefits on soil erosion control. Loess Plateau and Karst areas suffer the most severe water erosion in China, with distinct environmental conditions. This paper further revealed the targeted plantation strategy for these two regions: tree plantations in Karst areas should focus on the lithophyticity and drought tolerance of tree species, in the Loess Plateau should consider the trade-off between water consumption and soil erosion control.

The Jyndevad Experiment: Revealing long-term interactions between liming and phosphorus fertilization in a coarse sand soil

The Jyndevad field experiment, initiated in 1942 on a coarse sand soil in South of Denmark, explores the effect of four liming levels (0, 4, 8 and 12 Mg lime ha−1). These were in 1944 combined with two levels of mineral phosphorus (P) fertilizer (0 and 15.6 kg P ha−1 year−1), with or without a high initial dose of 156 kg mineral P ha−1. This study assesses interactions between liming and P fertilization on soil pH, Olsen-P contents and barley yields covering the last three decades. Annual P application improved barley yield regardless of liming, but the optimal liming level differed from year to year. This emphasizes the need for long-term field experiments to detect the complex interactions between liming and P availability on crop performance. The initial high P dose in 1944 and annual P fertilization increased Olsen-P contents in soil. The unlimed soil with pH(CaCl2) values below 4 had the highest Olsen-P content. The Jyndevad Experiment now harbors wide gradients in soil P (Olsen-P contents: 9–82 mg P kg−1 soil) and pH (3.6–6.9), providing a unique research platform for future studies on interactions between liming and P fertilization on coarse sand soils. We present a selection of studies that have used the Jyndevad Experiment to illustrate the research potential of the experiment.

Evaluating the environmental and agronomic implications of bone char and biochar applications to loamy sand based on sorption data

BackgroundThe widely adopted use of charred biomass for agronomic and environmental purposes; and the reported positive and deleterious effects necessitated the need for this study to ascertain the potential causes of the erratic results surrounding the use of charred biomass in agriculture and the environment. A batch sorption experiment was carried out to determine the sorptive and desorptive capacity of bone char and biochar on nitrate, ammonium, phosphate and sulphate concentrations in a loamy sand soil. The potential agronomic and environmental implications of the sorption data were also discussed.ResultsThe results indicated that bone char is richer in nutrient composition than biochar, with 70% more ability to sorb nutrients. The bone char and biochar sorption isotherms conformed to the H-curve isotherm type. Bone char and biochar have multiple layers of adsorption sites. Nutrient adsorption maxima, binding energy, and maximum buffering capacities of the soil were increased with the addition of bone char and biochar. The unamended soil was observed to retain as low as 6% of added nitrate to as much as 58% of added phosphate, while bone char retained 56% of added sulphate, 47% of phosphate, 76% nitrate and 64% of ammonium. Generally, bone char retained 60.6% of the added nutrients, while biochar retained 40.7% of the nutrients. The addition of bone char led to a 45.8% increase in the nutrient retention ability of the soil and a 36.1% increase with the addition of biochar.ConclusionThe nutrient sorption characteristics of biochar should be studied prior to its use as a soil nutrient amendment. It was concluded that bone char or biochar is a potential soil nutrient immobilizer; hence, applications for agronomic purposes should take cognizance of the native soil fertility so as to appropriately add fertilizer input before use.

Comparison of Nitrous Oxide Consumption of Paddy Soils Developed from Three Parent Materials in Subtropical China

Paddy soils developed from various parent materials are widely distributed in the subtropical region in China and have a non-negligible but unclear potential to consume nitrous oxide (N2O) due to long-term flooding. This study selected three of the most common paddy soils in subtropical China, developing from quaternary red soil (R), lake sediment sand (S), and alluvial soil (C), to study their total N2O consumption and total nitrogen (N2) production using N2-free microcosm experiments. These paddy soils were treated with N2O addition (N2O treatment) or helium (He) addition (CK treatment) and incubated under flooding and anoxic conditions. The results showed that three alluvial soils (C1, C2, and C3) consumed over 99.93% of the N2O accumulated in the soil profile, significantly higher than R and S soils (p &lt; 0.05). And the N2 production in three C soils was also significantly higher than other soils, accounting for 81.61% of the total N2O consumption. The main soil factors affecting N2O consumption in C, S, and R soils were soil clay content (p &lt; 0.05), soil sand content (R2 = 0.95, p &lt; 0.001), and soil available potassium (AK) (p &lt; 0.01), respectively. These results indicate flooding paddy soils, no matter the parent materials developed, could consume extremely large amount of N2O produced in soil profiles.

Nitrification inhibitor effect on manganese and phosphorus shoot concentrations in maize under different textured soils from northern Germany

High soil pH can result in Mn2+ and P deficiency, leading to crop yield losses. Therefore, supplying soil with NH4+-N fertilizer in stabilized or unstabilized form can increase soil Mn2+ availability and shoot concentration. Nitrification inhibitors (NIs) have been proposed to lower rhizosphere soil pH, thus improving plant P uptake and preventing P deficiency in soils with high pH. Thus, this study investigated whether NI-stabilized or unstabilized NH4+-N could increase Mn2+ availability in three differently-textured soils (sand, loamy sand, and silt loam) and promote Mn2+ and P shoot concentration in maize. Two greenhouse experiments were conducted to investigate the effects of applying NH4+-N fertilizer with or without the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) combined with different nitrogen (N) sources (calcium nitrate (CN), ammonium nitrate (AN), and ammonium sulphate (AS)). The measured variables were bulk and rhizosphere soil pH and Mn2+ availability, maize biomass, as well as Mn2+ and P shoot concentrations. The results indicated that DMPP-stabilized AS significantly decreased rhizosphere pH by 7.2 % in loamy sand soil texture compared with unstabilized AS. Similarly, only in the loamy sand texture, DMPP-stabilized AS increased Mn2+ availability and shoot concentration by 86 % and 47 %, respectively, relative to unstabilized AS. Furthermore, DMPP-treated AS and AN promoted P shoot concentration by 30 % and 21 % in the loamy sand and silt loam soil textures, respectively, relative to the corresponding N sources without DMPP. Conversely, DMPP did not impact the investigated variables in the sand texture for all N sources. Moreover, AN and AS increased biomass yield, Mn2+ availability, and shoot concentration by 72 %, 30 %, and 46 %, respectively, in relation to the CN fertilizer in the sand soil texture. In conclusion, this study confirmed the effectiveness of DMPP-induced rhizosphere acidification in enhancing Mn2+ and P shoot concentration in loamy sand soil textures, as well as P shoot concentration in fine-textured soil.

Nitrogen source regulates soil nitrification and nitrogen losses more than nitrification inhibitor and herbicide: A laboratory evaluation

AbstractIncreased environmental nitrogen (N) losses have prompted the use of enhanced efficiency nitrogen fertilizers, including nitrification inhibitors. However, the comparative effects of nitrification inhibitors with conventional nitrogen fertilizers and herbicides on soil nitrification and nitrogen losses remain poorly understood. This study evaluated the impact of a nitrification inhibitor (Instinct NXTGEN), two nitrogen sources (broadcast urea vs. injected aqueous ammonia), and a preemergence herbicide (Acuron) on (1) soil nitrification through a 25‐day soil incubation experiment and (2) NH3 volatilization, NO3‐N leaching, and N2O‐N emissions through a 31‐day soil column study in loamy sand soil. In both experiments, treatments included combinations of nitrification inhibitor versus no inhibitor, two nitrogen sources, and preemergence herbicide versus no herbicide. Results revealed that nitrogen source significantly influenced nitrification, with injected aqueous ammonia reducing nitrification by 33% compared to surface broadcast urea. Nitrification inhibitors and herbicide had no effect on soil nitrification. Injected aqueous ammonia reduced NH3 volatilization by 87% compared to surface broadcast urea, but the effect of the nitrification inhibitor on NH3 volatilization was inconsistent across both nitrogen sources. Injected aqueous ammonia led to 39% higher cumulative nitrogen (NO3‐N + NH4‐N) leaching than urea, while the nitrification inhibitor had an inconsistent effect on NO3‐N leaching across both nitrogen sources. No significant differences in N2O‐N emissions were observed among treatments, and the herbicide had no effect on any measured parameters. These findings suggest that nitrogen source plays a more critical role in regulating soil nitrogen losses than nitrification inhibitors or herbicides.

Identification of plant soil water and soil aeration corequisites: A management tool

AbstractPlant‐available soil‐water and adequate soil aeration within the root zone are essential corequisites for successful plant growth. Characterization of these two requirements for plant growth is generally done by independent measurements of water and air phase properties and functions in soil, with limited emphasis on their combined effect. This study investigated soil‐water characteristic (SWC) measurements in vadose soil profiles (up to 117‐cm depth) in six pasture soils to examine the combined behavior of soil‐water and diffusion‐controlled aeration within the root zone. The soil moisture measurements were made over matric potentials ranging from −1 to −1500 kPa using tension table and pressure plate apparatus. The van Genuchten model was used to parameterize the measured SWC curve, while the Millington–Quick model was used to derive soil‐gas diffusivity from measured soil physical properties. Based on two simple indices, derived to represent plant‐available soil‐water and soil aeration status at a given moisture content, we propose an assessment matrix, which illustrates how a soil satisfies the corequisites for successful plant growth, as it drains to different matric potentials upon irrigation. Results show a pronounced effect of soil texture and, to a lesser extent, soil structure on satisfying these corequisites. With the aid of the assessment matrix, we observed that loam, sandy loam textures exhibited a good overall performance, while sand, clay loam, and clay soils struggled to meet these corequisites during drainage.

Drained Bearing Capacity of Strip Footings on Two-Layered Sand Soil Slope

Drained Bearing Capacity of Strip Footings on Two-Layered Sand Soil Slope

Particle tracking-aided digital volume correlation for clay–sand soil mixtures

In this study, a novel, interdisciplinary method is introduced that merges fundamental geomechanics with computer vision to develop an advanced hybrid feature-aided digital volume correlation (DVC) technique. This technique is specifically engineered to measure and compute the full-field strain distribution in fine-grained soil mixtures. A clay–sand mixture specimen composed of quartz sand particles and kaolinite was created. Its mechanical properties and deformation behaviour were then tested using a mini-triaxial apparatus, combined with micro-focus X-ray computed tomography (μCT). The CT slices underwent image processing for denoising, segmentation of distinct phases, reconstruction of sand particles and feature extraction within the soil specimen. The proposed approach incorporated a two-step particle tracking method, which initially uses particle volume and surface area features to establish a preliminary matching list for a reference particle and then use the iterative closest point method for precise target particle matching. The soil specimen's initial displacement field was then mapped onto the DVC method's grid, and further refined through sub-voxel registration by way of a three-dimensional inverse compositional Gauss–Newton algorithm. The proposed method's effectiveness and efficiency were validated by accurately calculating the displacement and strain fields of the soil mixture sample, and comparing the results with those from a traditional DVC method. Given the soil's compositional and microstructural characteristics, these image-matching techniques can be integrated to create a versatile, efficient, and robust DVC system, suitable for a variety of soil mixture types.

Effect of Integrated Organic and Inorganic Fertilizer on, Growth of Garlic (Allium sativum L.)

Field experiments were conducted under loamy sand soil during rabi seasons of 2022-23 and 2023-24 at the Horticulture farm, S.K.N. College of Agriculture, Jobner. The experiment comprised of 28 treatment combinations of organic manures, inorganic fertilizer in main plot and 4 levels of foliar application through organic manures. The treatments with their symbols are described as under (100% RD of N through inorganic fertilizers (V1), 75% Inorganic fertilizers+ 25% vermicompost (V2), 75% Inorganic fertilizers+ 25% poultry manure (V3), 75% Inorganic fertilizer + 25% FYM (V4), 50 % Inorganic fertilizer + 50% vermicompost (V5), 50% Inorganic fertilizer + 50% poultry manure (V6), and 50% Inorganic fertilizer + 50% FYM (V7), were assigned to main plots and four levels of organics (Control ( O0), Vermiwash (O1), Panchgavya (O2), and Cow urine (O3), in sub plots and replicated thrice in split plot design. Garlic variety ‘G-282’ was used as a test crop. On the basis of two years result, application of 100 % inorganic fertilizer and foliar spray of Panchgavya was proved the most superior treatment combination in garlic representing the significantly higher growth parameter plant height of garlic at 60 and 90 days, number of leaf at 60 and 90 days and chlorophyll content.

Effect of Different Herbicides on Weed Dynamics in Wheat (Triticum aestivum L.)

A field experiment was conducted at Research farm, Vivekananda Global University, Jaipur during Rabi, 2023 on loamy sand soil. The experiment comprises 11 treatments of weed management practices in wheat (Weedy check, Weed free, Hand weeding at 30-35 DAS, 2,4-D ester @ 0.75 kg/ha at 30-35 DAS, Sulfosulfuron @ 25 g a.i. at 30-35 DAS, Carfentrazone ethyl @20 g/ha at 30-35 DAS, Metsulfuron methyl @ 4 g/ha at 30-35 DAS, Pinoxaden @60 g a.i./ha 25-30 DAS, Piroxofop- propargyl 15% WP @60g a.i./ha 30-35 DAS, Sulfosulfuron 75% + Metsulfuron 5% WG @ 32g a.i./ha at 30-35 DAS and Clodinafop-propargyl 15% + Metsulfuron methyl 1% @ 32 g a.i./ha at 30-35 DAS) thereby experiment was laid out in randomized block design and replicated thrice. Results showed that application of Sulfosulfuron 75% + Metsulfuron 5% WG @ 32g a.i./ha at 30-35 DAS at 30-35 DAS treatment resulted significant reduction in weed density, weed dry matter in comparison to most of the treatments while highest weed control efficiency and lowest weed index was recorded with the same treatment except weed free treatment. Clodinafop-propargyl 15% + Metsulfuron methyl 1% @ 32 g a.i./ha at 30-35 DAS was next superior treatment.

Modelling permanent strain behaviour of soil for flexible pavement design utilizing LWD measurements

ABSTRACT This study aims to improve understanding of unbound material behavior by modeling permanent strain using Light Weight Deflectometer (LWD) measurements, as part of VTI’s broader LWD research. By comparing permanent strain modelling from LWD data with Repeated Load Triaxial (RLT) tests on silty sand soils, it validates LWD data accuracy and explores material property influences on permanent strain parameters, revealing a clear correlation with water content and stress levels. Using LWD data validated against RLT tests, the study delves into material behaviour understanding under varied conditions, focusing on comparing model parameters of permanent strain prediction derived from LWD and RLT tests. Despite minor differences, both methods produce acceptable values, affirming the modelling approach’s robustness. The findings demonstrate LWD’s potential to improve pavement design by providing insights into permanent strain behavior that supports mechanistic-empirical approaches, leading to more efficient designs and better resource use for improved performance.

Biodegradable microplastics can cause more serious loss of soil organic carbon by priming effect than conventional microplastics in farmland shelterbelts

Abstract Globally, the widespread utilization of plastic products has resulted in the accumulation of microplastics (MPs) in the soil. MPs have the potential to impact the loss of soil organic carbon (SOC). Nevertheless, the influence of different types of MPs on SOC loss remains uncertain. In this study, a 38 day incubation experiment with two kinds of conventional MPs (polyethylene, polypropylene) as well as two kinds of biodegradable MPs (polyhydroxyalkanoate [PHA], polylactic acid [PLA]) were added into three types of soil (loam, sandy loam, and sandy soil) in farmland shelterbelts, and the sources of CO2 emissions was distinguished by the difference in 13C isotope abundance between the biodegradable MPs (PHA and PLA) (−10.02‰ to −9.92‰) and the soil (−24.39‰ to −22.86‰) (&gt;10‰). In conjunction with the structural characterization of MPs, as well as soil physicochemical properties and microbial characteristics, we observed that the conventional MPs did not degrade in short term incubation, but significantly enhance soil‐derived CO2 emissions by altering the dissolved N content (‐N and dissolved total N [DTN]) and reducing microbial biomass carbon content only in sandy loam soil (p &lt; 0.05). Biodegradable MPs degraded significantly, and enhanced soil‐derived CO2 emissions by reducing soil DTN and ‐N contents in loam, sandy loam and sandy soil (p &lt; 0.05). Overall, the input of biodegradable MPs causes a more serious loss of SOC than conventional MPs as the soil sand content increased in short term incubation, which needs to be considered in predicting the global impact of increasing biodegradable MPs pollution. Read the free Plain Language Summary for this article on the Journal blog.

Genetic and environmental drivers of legume cover crop performance: Hairy vetch

AbstractAmong 50 environments in the United States, we screened 35 hairy vetch (Vicia villosa Roth.) lines for traits of interest to cover cropping. We analyzed the influence of genotype, environment, and the genotype‐by‐environment interaction (G × E) on biomass, vigor, winter survival, emergence, flowering time, and nitrogen fixation. To explore how environments and G × E impacted each trait, we associated environment predictions and G × E loadings with weather and soil parameters. Environment had the largest influence on all traits, representing more than half of the variance. Environment predictions were significantly associated with weather and/or soil parameters for each trait. Biomass was associated with growing degree days, winter survival with freezing degree days without snow cover, growth stage with shortwave radiation, and emergence with soil texture. The G × E interaction was larger than genotypic variance for all traits except for winter survival and flowering time. The G × E interaction loadings were associated with soil sand content for biomass, air temperature for fall vigor and emergence, and snow cover for winter survival. Although it represented the smallest proportion of total variance, genetic effects were significant for all traits except for emergence, Ndfa, %N, and C:N. New hairy vetch breeding lines were superior to all commercially available lines for biomass and winter survival. Biomass harvest timing did not significantly change line rank, indicating that top‐performing lines can be used in diverse management systems. To select for high nitrogen contribution to subsequent crops, breeding programs can indirectly select for biomass rather than expensively evaluating symbiotic nitrogen fixation.

Landscape Dynamics and Environmental Fragility Zoning in Hinh River Basin: Insights for protecting natural ecosystems

The landscapes in the Hinh River Basin are crucial and highly sensitive to climate change for the coastal province of Phu Yen and the entire south-central coastal region of Vietnam, offering vital environmental services to its downstream areas. Hinh River Basin has a rich system of rivers and streams and abundant surface water resources. However, it remains one of the region's top localities at risk and a very vulnerable region. This study aims to evaluate the changes in landscape (LC) over 10 years (2010-2023) and predict LC over the next six years using machine-learning (ML) algorithms on Google Earth Engine. To achieve these study goals, we establish: (i) potential environmental fragility (PEF) levels based on: terrain slope; geological domains; river hierarchy; percentage of sand in soil; annual mean precipitations; and (ii) emergent environmental fragility (EEF) levels through the addition of LC parameter to model. The methodology includes integrating the Analytic Hierarchy Process (AHP) into a Geographic Information System (GIS). Results show that three LC types (water, annual industrial crop, forest) are related to extremely high EEF. The predictive model suggests that, by 2030, the forest and annual industrial crop LCs in the study area will increase by around 20%. The analysis results show that there has been an increase in the area of planted forests, which can confirm the futher effectiveness of agricultural, forestry, afforestation and forest protection programmes in the study area (Plan for the implementation of forestry development strategy for the period 2021-2030, with a vision to 2050, Phu Yen Province, No 126/KH-UBND 13/7/2021; and Decision on the approval of the project for planting 15 million trees in Phu Yen Province for the period 2021-2025, No 1646/QĐ-UBND 16/11/2021).

Impact of polyvinyl alcohol application and wheat straw mulching on soil loss and infiltration rate in semi-arid tropics

A study was conducted at Punjab Agricultural University, Ludhiana, Punjab, with the aim of monitoring soil loss and infiltration rate in loamy sand soil. The study focused on the effects of applying polyvinyl alcohol (PVA) and mulch under simulated rainfall conditions. The experimental setup involved testing three levels of PVA (0.5%, 0.75%, and 1.0%), one level of wheat-straw mulch (600 g/m2), and a Control treatment (untreated soil). Each of these treatments was replicated four times. The lowest soil loss (20.9 g/m2) was recorded under the 1.0% PVA treatment, while the highest (120.1 g/m2) was seen under the 0.5% PVA treatment. The 1.0% PVA treatment showed a significant reduction in soil loss compared to the 0.5% PVA, 0.75% PVA, mulch, and Control treatments, with reductions of approximately 82.6%, 45.1%, 81.2%, and 89.6%, respectively. Regarding infiltration rates, the Control treatment exhibited the lowest rate (2.4 cm/h), while the 1.0% PVA treatment displayed the highest rate (9.6 cm/h). Additionally, the use of mulch led to a 44.7% reduction in soil loss compared to the treatment without mulch, likely due to the mitigated impact of raindrops. The infiltration rate was significantly higher (4.8 cm/h) under the mulched treatment compared to the unmulched treatment (2.4 cm/h). Overall, the application of PVA and mulch resulted in a drastic reduction in soil loss, likely attributable to the enhanced stability of soil aggregates, improved infiltration rate, and reduced runoff.

Degradation of Emamectin Benzoate in the Aquaculture Pond Environment under Tropical Climatic Condition

Emamectin Benzoate (EMB), is an anti-parasitic drug, commonly used in aquaculture for prevention and control of parasitic infestations. The drug enters the environment through uneaten feed and faeces, ultimately accumulating in aquaculture pond sediment. Present study reports the influence of abiotic factors like, sunlight exposure (2,454 to 117,500 lux), pH, salinity and soil texture on the degradation of EMB in aquaculture pond water and sediment as per Organization for Economic Cooperation and Development (OECD). Results showed that the degradation of EMB in both water and sediment followed first-order kinetics, resulting in half-life of 5.6 days in water and 12.4 days in sediment when exposed to natural sunlight. Higher degradation of EMB was observed under alkaline conditions (pH 8.5) and at lower salinity (0.5ppt). EMB degradation is accelerated in loamy sand soil when exposed to sunlight. Results of the study suggest that in countries like India, where ample sunlight exposure is prevalent throughout the year, EMB degradation in aquaculture pond environment occurs at a rapid pace reducing the risk of accumulation in water or sediment.

Soil cross breeding: Mechanical strength analysis of intermixed soils used as unfired earth brick

Mechanical strength of brick is significantly influenced by soil properties, deeming some soils unusable. This paper investigates the effect of mixing soils from different sources, Hyogo (a chlorite soil) and Tokyo (an albite soil) from Japan, on the flexural and compressive strength of unfired earth brick. Before conducting strength tests on moulded bricks made from original soil mixes and intermixed soils, both soil samples were individually separated into two portions, sand and fines. To better understand the strength behaviour of the resulting brick specimen, the physical and chemical properties of used raw materials were characterised using various techniques including X-ray computed tomography (X-ray CT) X-ray diffraction (XRD), water and nitrogen sorption, X-ray fluorescence (XRF) and ionic conductivity. The results revealed that the replacement of the fines portions in unadulterated soil mixes induced an increase in flexural and compressive strength for brick specimen made with albite soil, while significant reduction in strength was recorded with brick specimen made with fines portion replaced in chlorite soil. Furthermore, the former intermixed soil exhibited higher strengths than specimen made from unadulterated soils. Chlorite clay minerals comprised of desired properties to enhance performance of albite soil sand particles in a brick composite. This justified the dependence of selected soil parameters that play critical roles in the performance behaviour of the produced bricks. The obtained findings could serve as guidelines to production and performance enhancement of unburnt brick by amalgamating various soils.