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The calcareous materials used in constructing the Phaya Thon Zu temple at the Bagan historical sites in Myanmar are mortars, plasters, and stuccos. Among them, the mortars and plasters are a mixture of original and new materials used for recent conservation treatments. In this study, the making techniques were examined through analysis of calcareous materials by production period. All calcareous materials have a mineral composition similar to soil, except calcite. Stuccos have the most refined aggregates, homogeneous particle size, and the highest lime and organic contents. They were designed to improve ease of carving and weathering resistance, considering the unique characteristics of the stuccos. Because all calcareous materials were mixed with soil, the origin of the clay materials was analyzed. It was concluded that the mortars were produced by mixing clay and sandy soil, and the original mortars showed characteristics similar to soil. It is highly possible that sandy soil from around the Htillominlo temple was used to produce new plasters, and it is estimated that a mixture of clay soil was used for the original plasters and stuccos. A clear provenance interpretation of the original and raw materials used for each construction and the mixing ratio of clay materials need to be discussed through experiments, along with the estimated provenance area of the raw calcareous materials. [ABSTRACT FROM AUTHOR]

Coix lacryma-jobi L., an annual or perennial plant belonging to the Poaceae family, has long been cultivated as a food and medicine plant in China. In recent years, coix cultivation for high yields and good quality has become a research hotspot in Southwest China. Soil optimization is essential for improving crop growth. To ensure the robust establishment of coix plants, eight soil substrates, prepared from three typical soils, i.e., red clay soil, peat soil, and sandy soil, were used to cultivate two local coix varieties (Pu coix from Fujian Province, China; Qi coix from Hebei Province, China), and the plant growth and root coixol content of the two coix varieties were investigated. It was found that coix plants could maintain growth when cultivated with peat soil or sandy soil, but red clay soil was unfavorable for coix growth. The mixtures of sandy soils and peat soils resulted in synergistic benefits for coix growth and root coixol levels over the effects of sandy soil or peat soil alone. In conclusion, the mixtures of sandy soils and peat soils with appropriate proportions (sandy soils/peat soils = 2:1) were suggested as an ideal soil substrate for coix cultivation. The results provide valuable guidance for the establishment of coix plants, which could contribute to high yields and good quality in coix cultivation. [ABSTRACT FROM AUTHOR]

Bacterial leaf streak caused by Xanthomonas vasicola pv. vasculorum (Xvv) is an emerging disease in several corn-producing regions around the world. In Brazil, there is a lack of information on the survival of this bacterium in soil and crop residues. Thus, the objective of this study was to determine the survival of Xvv in soil and also in infected corn crop residues under the humid subtropical climate of southern Brazil. The survival of Xvv in soil was initially investigated in sandy and clayey soils maintained at 20, 25 and 30 °C under controlled conditions. The survival of the bacterium under field conditions was studied in artificially infested clayey soil. The survival of Xvv in corn crop residues was investigated in infected residues maintained on the soil surface or buried in the soil at 20 cm deep. Under controlled conditions, regardless of the type of soil, the bacterium survived longer at 20 °C than at higher temperatures. The bacterium survived for 40 days in clayey soil kept at 20 °C and four days in sandy soil maintained at 30 °C. Under field conditions, the survival of Xvv in the soil was only for 48 h and in infected corn crop residues for up to 15 days in the samples maintained on the soil surface. In samples of infected corn residues buried in the soil, the bacterium was only detected at the time the experiment was set up. In general, the results obtained in this study revealed that Xvv survives for a short period of time in soil and in infected corn crop residues under humid subtropical conditions. Therefore, soil and corn residues may not be highly important sources of primary inoculum for the development of bacterial leaf streak on corn crops under these conditions. [ABSTRACT FROM AUTHOR]

The timing of nitrogen fertilizer application in vineyards can determine the amount of nitrogen (N) absorbed, distributed, and accumulated in grapevine organs. The study aimed to evaluate the annual contribution of N from urea, applied at different times in Cabernet Sauvignon, grown in sandy and clayey soil in a subtropical climate. The sandy soil received 21.42 kg N ha−1 and the clayey soil 30 kg N ha−1, both enriched with 3% excess 15N atoms, applied at different times. The N derived from the fertilizer in grapevines, at all times of N application, and in sandy and clayey soil did not exceed 8%, with the highest values being observed in annual organs, especially in the leaves. The application of N marked at the phenological stages of IBB (50% at beginning of budbreak + 50% at full budbreak) enabled greater absorption of N derived from the fertilizer by the vines grown in both sandy and loamy soil. The N present in the annual organs (leaves, berries, stalks, and shoots) and in the perennial organs (stems and canes) of Cabernet Sauvignon grown in sandy and clayey soil was derived in greater percentages from the soil. [ABSTRACT FROM AUTHOR]

Interactions between adjacent piled-raft foundations may induce additional settlement and cause the tilt of the structure. This case study investigates the long-term performance of a large piled-raft foundation system supporting high and heavy alumina solution storage tanks based on field measurements and three-dimensional (3D) numerical simulations. To properly consider the interactions among rafts, piles, and soils; the elastoplastic behavior of clayey and sandy soils; and the consolidation behavior of soil after construction, a 3D finite-difference code was utilized for the numerical modeling. Two undrained mechanical analyses were conducted to simulate the installation of foundations/tanks and the filling of alumina solution into the tanks, while two coupled hydromechanical analyses were performed to model the period between the two undrained stages and the stage after tank filling, respectively. The predictive capability of the numerical model was checked by comparing the simulation results first with single pile load test data and then with in situ settlement measurements at different locations of the piled-raft foundations. The long-term behavior of the piled-raft foundations was further investigated by analyzing various aspects including the axial force variation along the pile at different locations, the time-settlement relation at monitoring locations, the vertical effective stress increment and displacement of soil, and the differential settlement between monitoring locations. Based on the simulations, the tilt of the platform was mainly due to the superposition of additional stresses near the centerline of the two rows of piled-raft foundations. Finally, parametric studies were conducted to investigate the interactions among the piled-raft foundations at different pile length configurations. The results show that by properly increasing the length of the piles near the centerline of the two rows of piled-raft foundations, the differential settlement of the platforms can be mitigated. [ABSTRACT FROM AUTHOR]

Tomato is valued for its nutritional importance and contribution to countries' GDP. Despite the importance of tomatoes, tomato cultivation remains a challenge in some cities, particularly Kumba, Cameroon. This results from a vast knowledge gap for a suitable variety and agronomic management practices. Thus this work was set out to investigate the response of three tomato varieties under organic, foliar, and granular inorganic fertilization at the Kumba I subdivision. This work comprised two factors; variety having three levels (Cobra F1, Rio Grande, and Kiara tomato varieties) and fertilization having four levels (control, NPK 20:10:10 granular fertilizer, Foliar NPK 20:10:10 inorganic fertilizer, and Poultry manure) given twelve treatment combinations replicated three times randomly in a factorial design. Data was collected on soil physicochemical properties, plant growth parameters and fruit yield. The results showed that the variety did not significantly affect soil physicochemical properties, but soil physicochemical properties were significantly affected by fertilization. Poultry manure had the best OC (5.22 %), Ntot (1.73 g/kg), and Pavail (14.63 mg/kg), while K was highest (2.93 meq/100g) in NPK 20:10:10 granular fertilization. Rio grande, in combination with poultry manure, had the best plant growth; plant height (77.3 cm), number of branches (17), number of leaves (197), and leaf area (47.1 cm2). Cobra F1, in combination with foliar NPK 20:10:10 granular and poultry manure, had the best fruit yield; 13.42 tha-1 and 13.56 tha-1, respectively while Kiara variety at the control treatment had the lowest yield (8.36 tha-1). Thus Cobra F1 variety in combination with poultry manure yielded the best result from this study and offers the best option for tomato cultivation in the sandy clay soils of Kumba, Cameroon. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) emissions affect the environment, the climate, and human health and originate mainly from agricultural sources like urea fertilizers. Such losses from urea fertilizer can be avoided by different application techniques like incorporation. However, the knowledge of the effect of these techniques on NH3 emissions is very limited and ambiguous since incorporation can also promote nitrous oxide (N2O) emissions. Three different principles of fertilizer incorporation methods were compared in three different soils (sandy, loamy, and clayey) at two moisture levels of 70% and 30% water-holding capacity (WHC), shallow mixing at 2 cm, injection with the slit technique at 5 cm, and deep complete incorporation at 5 cm simulating plow incorporation. The laboratory study was conducted with open dynamic incubation chambers where NH3 emissions were monitored with washing bottles while N2O emissions were studied with gas chromatographic (GC) measurements. The highest cumulative NH3 emissions occurred at low soil moisture levels in sandy soil (34% of the N applied). A maximum reduction in emissions by 87% was achieved with slit injection and 82% with deep injection compared to standard surface application. The reduction effect was positively related to increasing clay content. N2O emissions were delayed and highest from sandy soil. Overall, all urea incorporation techniques showed great potential for mitigating NH3 emissions on the clayey soil; for sandy and drier soils, only deeper or closed slot injection were consistently effective. However, connected to the surface incorporation at the higher moisture level, a relevant increase in N2O emissions compared to surface application was observed. Therefore, an increase in N2O emissions by urea incorporation may rule out specific incorporation techniques for NH3 emissions reduction from field-applied urea. In agricultural practice, a lower reduction in NH3 by fertilizer incorporation can be assumed in sandy soils or under dry soil conditions, as well as a more challenging technical implementation. [ABSTRACT FROM AUTHOR]

This study evaluates a binary mixture of fly ash and lime as a stabilizer for natural soils. A comparative analysis was performed on the effect on the bearing capacity of silty, sandy and clayey soils after the addition of lime and ordinary Portland cement as conventional stabilizers, and a non-conventional product of a binary mixture of fly ash and Ca(OH)2 called FLM. Laboratory tests were carried out to evaluate the effect of additions on the bearing capacity of stabilized soils by unconfined compressive strength (UCS). In addition, a mineralogical analysis to validate the presence of cementitious phases due to chemical reactions with FLM was performed. The highest UCS values were found in the soils that required the highest water demand for compaction. Thus, the silty soil added with FLM reached 10 MPa after 28 days of curing, which was in agreement with the analysis of the FLM pastes, where soil moistures higher than 20% showed the best mechanical characteristics. Furthermore, a 120 m long track was built with stabilized soil to evaluate its structural behavior for 10 months. An increase of 200% in the resilient modulus of the FLM-stabilized soils was identified, and a decrease of up to 50% in the roughness index of the FLM, lime (L) and Ordinary Portland Cement (OPC)-stabilized soils compared to the soil without addition, resulting in more functional surfaces. [ABSTRACT FROM AUTHOR]

Compressed stabilized soil block is a sustainable building material primarily made up of stabilized damp soil compressed under pressure. Soil properties and the type of the stabilizer used in producing compressed soil blocks have a significant impact on the quality and behavior of the soil blocks. This study presents the physical and mechanical behavior of lime-cement-stabilized compressed interlock soil blocks produced from two types of natural soil. The two types of soil have different index properties and mineral oxide compositions. Lime-cement combination and cement standalone was used as a binder in the production of test sample blocks depending on the index properties of the soil. 2%lime + 6%cement, 3%lime + 8%cement, and 4%lime + 10%cement were used for the soil block produced from silty clay soil of medium plasticity index. On the other hand, 6%, 8%, and 10% cement by dry mass of soil were used to stabilize silty sand soil. The behaviors of the blocks, such as dry density, the initial rate of water absorption, saturated absorption of water, compressive strength, and stress-strain relation, were examined. The result shows that the compressed soil blocks produced from lime-cement-stabilized silty clay soil has a low rate of initial water absorption and a low dry unit weight when compared to cement-stabilized sandy soil blocks. Soil blocks produced from cement-stabilized silty sand soil attain greater compressive strength by more than 50% of the compressive strength of silty clay soil blocks stabilized by a combination of lime and cement at 60 days after production. The initial tangent modulus of the soil blocks produced using a manual compressing machine from a clay soil stabilized by the lime-cement proportions of 2%L + 6%C, 3%L + 8%C, and 4%L + 10%C is about 1,700 MPa–2,300 MPa with a dry density greater than 1,660 kg/m3. [ABSTRACT FROM AUTHOR]

Co-application of fertilisers and biofertilisers increases solubility and concentration of nutrient elements in the soil. However, information on the effect of P fertiliser and rhizobium inoculation on the concentration of mineral elements in the rhizosphere of field-grown chickpea in contrasting soil types is lacking. We assessed the effect of phosphorus fertiliser, rhizobium inoculation, and rhizobium inoculation plus P fertilizer on the concentration of nutrients in the rhizosphere of 2 chickpea genotypes (ACC#1 & ACC#5) at clay and sandy soil sites in two consecutive years. ACC#5 accumulated higher amounts of rhizospheric nutrients than ACC#1 in both soil types despite the variable response to fertiliser treatment. Rhizobium inoculation plus P fertiliser resulted in higher accumulations of rhizosphere N (7-219%), P (20-348%), K (9-365%), Ca (2-155%) and Zn (15-259%) compared to the other fertiliser treatments suggesting an additive effect of P fertiliser and rhizobium inoculation. Moreover, the effect of fertiliser treatments was more pronounced in the clay than the sandy soil. Our investigation is the first to document the effects of fertiliser treatment, genotype, and soil type on the accumulation of rhizosphere nutrients in field-grown chickpea. However, we propose further studies, incorporating more cultivars and environments, before making practical recommendations. [ABSTRACT FROM AUTHOR]

The selectivity and efficacy of protoporphyrinogen oxidase (PROTOX) inhibitor herbicides in cassava varieties depend on product formulation, dosage, and soil texture. The aim of this study was to assess the selectivity and efficacy of flumioxazin and sulfentrazone in the cassava variety 'IPR B36' and the clone 'VN 117'. Two experiments were carried out: one in a clayey soil and one in a sandy soil. Both experiments were laid in a split-plot randomized block design with three replicates. The two cassava varieties were used as main plots, with subplots consisting in 10 treatments including, flumioxazin at 50, 75, 100, and 125 g ha-1; sulfentrazone at 250, 500, 750, and 1000 g ha-1; one weed-free control, and one unweeded control. Flumioxazin (=75 g ha-1) and sulfentrazone (=250 g ha-1) achieved mean weed control rates > 70 and 90% in both types of soil for up to 90 days after application. Flumioxazin exhibited fewer residual effects on the cassava varieties than sulfentrazone, particularly in clayey soil. Flumioxazin was selective to the different cassava varieties planted in both soil types, whereas sulfentrazone was more selective in clayey soil. PROTOX inhibitors were effective in controlling weed growth in cassava plots, and there were no varietal differences in herbicide selectivity; however, the use of sulfentrazone should be restricted to maximum spray rates of 250 g ha-1 in sandy soils. [ABSTRACT FROM AUTHOR]

The priming effect (PE) induced by exogenous organic substrate input plays an important role in the soil carbon balance. However, little is known about how the chemical complexity of different exogenous organic substrates and soil type regulate the PE. Therefore, we conducted a 72-day incubation experiment involving the addition of three 13C-labelled substrates (glucose, starch and cellulose) to two forest soils with contrasting textures (i.e., a fine-textured clay soil and a coarse-textured sandy soil). Cellulose had a lag phase in the mineralization process but induced greater PE compared to glucose and starch in both soils. Moreover, exogenous organic substrate input generally induced negative PE and net soil C gain in the clay soil, but positive PE and net soil C loss in the sandy soil. The negative PE in the clay soil was negatively correlated with exogenous C mineralization, indicating that preferential substrate utilization was the mechanism controlling PE in the clay soil. However, the positive PE in the sandy soil was positively correlated with exogenous C mineralization, microbial biomass C (MBC), cellulase activity and soil inorganic N content, suggesting that co-metabolism was the mechanism regulating PE in the sandy soil. The significant difference in PE between the clay and sandy soils was mainly attributed to their significant differences in soil MBC, dissolved organic C (DOC) and SOC contents, followed by soil texture (particularly the clay content), available N content and pH. Overall, our results demonstrate that soil type is much more important than substrate type in regulating the PE and that the clay soil has a greater C storage potential than the sandy soil following the input of exogenous organic substrates. [ABSTRACT FROM AUTHOR]

Mat foundations are most typically used in locations featuring weak soils such as soft clays and silts, particularly when building in demanding geotechnical conditions. Because of their poor engineering characteristics and significant difficulties associated with workability, these soils are often removed or avoided by excavating down to a specific depth. However, if thick layers are present, their removal becomes unpractical, costly, and creates inconvenience during construction. To overcome this issue, various reinforcement strategies can be adopted. In this study, the use of stone columns under mat foundations was investigated via numerical modeling. Two scenarios were compared: one in which stone columns were installed without any soil removal and another in which a layer of soft ground was removed and the foundation was installed without any ground treatment. Numerical results showed the clear beneficial effect of stone columns, which can significantly reduce settlements even in the presence of a thick deformable soil layer. [ABSTRACT FROM AUTHOR]

Processes of soil restoration in anthropogenically disturbed soils is an urgent topic in modern ecology and nature management. Being mediator between mineral soil composition and plant vegetation, soil microbial community is important factor of soil restoration processes. Analysis of main soil nutrition components followed by 16S amplicon sequencing are sufficient methods for primary analysis of novel locations. Here is the primary analysis in a novel location in Northwest Europe (Russia). Main nutrition parameters (pH, P, Na and NH4+) and 16S rDNA Illumina amplicons were explored in abandoned soils from sandy pit quarry (2 sites) and refractory clay mining dumps (4 sites). Microbial communities of mature soils and dumps are variable and different in terms both nutritional and microbial components. pH, N and TOC are strong predictors for microbial composition. Dumps of refractory clays pQ_2 are non-developed soils, highly acidic and form specific microbial community. Differences between dumps and mature soils in both pre-quaternary and quaternary soils are connected with specific bacterial taxa. Those taxa are connected more with plant composition, not the soil properties themselves. The exact changes in microbial community are unique for different soils and areas. [ABSTRACT FROM AUTHOR]

Easily found in humid and shady places, Maranta sobolifera has spread in agricultural areas. However, the lack of information on the development of the species in different environments makes it difficult to understand its adaptive capacity. This paper evaluated the morphophysiological changes of M. sobolifera plants to sun exposure and soil textures. In a completely randomized experimental design and split plots, the main plots corresponded to light exposure and the subplots to soil textures. Gas exchange indices, stomatal density, chlorophyll a, b and total contents, macronutrients and dry mass were evaluated. The lower incidence of luminosity increases the photosynthetic rate by an average of 43% and 33% in clayey and sandy soils, respectively. Stomatal density was higher in full sun, while chlorophyll contents a and b were higher in shaded plants. The N and K contents in leaves, stems and roots were higher in shaded plants by up to 37%. The P content in the stem was 69% and 48% higher in plants grown in clayey and sandy soil, respectively. Dry mass was 26% higher in shaded plants compared to plants grown in full sun. In clayey soil, the total dry mass was 42% higher in relation to plants in sandy textured soil. It is concluded that M. sobolifera plants show morphophysiological changes (>stomatal density) that help adapt to full sun. However, under the canopy of agricultural crops, this species can compete intensely for nutrients, especially in clayey soils. [ABSTRACT FROM AUTHOR]

Images from unmanned aerial vehicles (UAV) can serve as a baseline for studies in weed science, complementing observations obtained in the ground. The objective of this work was to determine soybean (Glycine max (L.) Merr.) plant injury caused by pre-emergence herbicides in sandy and clayey soils, using a low-cost UAV. The experiment was conducted in a randomized complete block design, with four replicates and seven treatments consisted of herbicides (diclosulam, chlorimuron, sulfentrazone, flumioxazin, and S-metolachlor), hand weeded and untreated treatments. Ground-based evaluations were carried out to assess soybean crop injury, plant stand, leaf chlorophyll content, plant height, canopy distance and grain yield. Images were taken using a UAV equipped with an RGB (red green and blue) camera. Soybean plants sprayed with diclosulam had lower plant reflectance in the R (98.9), G (147.1) and B (74.3) range than the other treatments in sandy soil. In clayey soil, hand weeded treatment had higher plants (30.8 cm) and untreated favored smaller plants (24.9 cm) compared to herbicide treatments. In sandy soil, soybean yield of all treatments was similar, however in clayey soil, soybean yield treated with chlorimuron and flumioxazin was higher than 5000 kg ha-1 and better than the others treatments. The nutrient-poor soil (sandy) may have aggravated the plant injury caused by herbicides and explain the lower yield observed compared to clayey soil. It was determined soybean plant injury caused by pre-emergence herbicides with the use of unmanned aerial vehicles, providing complementary results to ground-based measurements, indicating the potential of this technology for low-cost evaluations in weed science. [ABSTRACT FROM AUTHOR]

Water availability explains a large part of the spatial and temporal yield variability of ware potato in the Netherlands. Climate change is projected to lead to greater variability in water availability. Therefore, an accurate simulation of crop yield as a function of water availability is of high importance. Many crop models can simulate water-limited potato yields, but as detailed experimental data on drought and oxygen stress are scarce, models are often not well calibrated and evaluated. We set up a large experiment and an on-farm observational trial to calibrate and evaluate the simulation of water-limited yield of different potato cultivars across the Netherlands. In addition, we investigated the required model complexity to accurately simulate water-limited potato yields. The crop growth model WOFOST was used for simulations either as a single model or coupled with SWAP. Yields were simulated applying either only drought stress or by including both drought and oxygen stress. We employed two methods for simulating oxygen stress in SWAP-WOFOST. The calibration improved accuracy of simulated water-limited yields as demonstrated in our model evaluation. Both on sandy and clayey soils, water-limited yields were best simulated using SWAP-WOFOST while simulating oxygen stress using a process-based method in combination with a rooting density that decreases linearly with rooting depth. On sandy soils, the bottom boundary condition of free drainage was applicable. On clayey soils measured groundwater levels (or soil water pressure heads when measurements are not available) should be used as bottom boundary condition. On sandy soils both WOFOST and SWAP-WOFOST may be used, as results were similar. On clayey soils, WOFOST is less suitable, as it cannot simulate capillary rise. SWAP-WOFOST however has many options and parameters, which can result in large differences in results. Hence, a careful model set up and evaluation is required for each application. • The models WOFOST and SWAP-WOFOST have been recalibrated for water-limited potato yields. • On clayey soils with shallow groundwater levels SWAP-WOFOST outperformed WOFOST. • On clayey soils there seemed to be an effect of oxygen stress on yield. • Effects of oxygen stress were smallest in WOFOST, and largest in SWAP-WOFOST using a process-based method. • On sandy soils there was an inconsistent benefit of using SWAP-WOFOST over WOFOST. [ABSTRACT FROM AUTHOR]

The liquefaction phenomenon may originate in fine sandy - silty type of soils subjected to dynamic effects, low plasticity clays and even in soils with gravels based on the magnitude of applied acceleration. The mechanical or chemical soil improvement techniques have been used to prevent this problem. The mixing or grouting operations of sodium polyacrylate, which has a high-water absorption capacity, is one of the chemical soil improvement techniques. The frost behavior of this material, which turns into a gel form when react with the water in the environment, is not known in the permafrost areas. Within this purpose, sandy specimens including 5.00%, 10.00%, 15.00%, and 20.00% sodium polyacrylate gel as well as reference ones, were frozen at -20C° and unconfined compression tests were applied. Moreover, the tests were repeated for additional specimens containing 5.00% bentonite clay by weight. Although the unconfined compressive strength of all samples improved according to the increase in the amount of water with the gel content, about 14.00% lower values were obtained in specimens containing bentonite. On the other hand, the unit strain values of frozen samples without bentonite increased, while reduction observed in samples with bentonite. The viscous structure, that is in gel form inside the soil, dissipates volume increase during the freezing process and prevents the frost heave problem. However, the loss of bearing capacity should be considered in case of insufficient saturation in liquefaction sensitive sandy soils improved with sodium polyacrylate. [ABSTRACT FROM AUTHOR]

Deinking paper sludge (DPS) soil amendments have potential as a climate change mitigation strategy. Understanding how DPS application affects carbon mineralization in different soil textures is crucial but has not been well investigated. We performed a 120 days incubation experiment to evaluate the effect of soil texture and DPS amount on CO2 emissions. Three different textures were tested: silty clay, sandy-silt and sandy with three DPS doses: 0, 30 and 60 t.ha-1. Results showed that DPS mineralization without soil seemed very rapid with a high mineralized carbon amount (more than 2.500 gC.kg-1DPS), but did not reach the stable phase. For amended soils, soil texture effects are marked at the end of incubation. The cumulative carbon mineralization depended significantly on soil texture and DPS doses with a significant interaction. Among all soils with different dose application, the highest cumulative carbon mineralization was revealed for silty-clay soil by applying 30 t.ha-1 as well as 60 t.ha-1 of DPS. However, the lowest values occurred for sandy soil. Only this latter achieved the stabilization phase after 120 days and therefore stopped CO2 emission. The highest potential mineralization rate (C0) was achieved for silty-clay soil by applying the two DPS doses. The mineralization rate (C0*k) was two times higher for this soil than the sandy soil. The kinetic deviation of carbon mineralization applying the highest DPS doses (60 t.ha-1) is similar for the four studied soils because of C-decomposition blockage. These findings highlight the necessity to consider the combined effects of the DPS amount and soil texture for assessing C release in DPS-amended soils. [ABSTRACT FROM AUTHOR]

Soil evaporation concerns water and our life support sources, which are important for agriculture or for climate change prediction science. A simple instrument based on the nonsteady-state (NSS) technique for soil evaporation measurement appears suitable. However, because the NSS chamber technique is highly invasive, special care should be provided to correct the wind speed influence on the evaporation process. Soil evaporation is a complex process that involves many soil and air characteristics. Measurement chamber installation on the soil and its head deployment may perturb these characteristics. We therefore had to minimize differences or to correct the measurements. Most of the differences between bare soil and soil with a deployed chamber head can be minimized, except for the wind speed influences that are not reproducible inside a chamber head. Meanwhile, as the wind influences depend on numerous variables that are not monitorable in real time, a self-calibrating chamber with a corresponding protocol called the Autocalibrated Soil Evapo-respiration Chamber (ASERC) was developed to make the measurements easily corrigible on bare soil with a unique variable (wind speed, WS), regardless of the soil composition, soil texture, and other soil or air meteorological variables. A simple protocol followed by this chamber allows us to determine the soil evaporation wind speed susceptibility (Z) and to correct the measurements achieving 0.95 as the coefficient of determination. Some interesting findings on sandy and clayey soil evaporation measured during laboratory calibration and "slow" sensor simulation will also be reported in the two appendices. [ABSTRACT FROM AUTHOR]

The physical and mechanical behavior of soil polymer composites tightly depends on the properties and structures of both soil and polymer. This study aims to investigate the effect of glass transition temperature as one of the most important characteristics of adhesive resins of acrylic polymers on the geotechnical behavior of soils that have not been fully covered by previous studies. To achieve that, three similar copolymers of methyl methacrylate-co-butyl acrylate with different glass-transition temperatures of 1°C, 33°C, and 51°C were synthesized, and two representative specimens of cohesive (kaolinite clay) and noncohesive (sand) soils were chosen to perform a full investigation of the consequential changes in the physical and mechanical behavior. A series of laboratory tests, including the Atterberg limits tests, the unconfined compressive strength tests, direct shear tests in soaked and unsoaked conditions, swelling tests, and odometer tests, were conducted on untreated and treated soils with synthesized polymers. The results showed a salient enhancement in the cohesion and the unconfined compressive strength value of both soils. However, the polymer with a glass-transition temperature near to ambient temperature led to a greater increase in the compressive and shear strength of stabilized soil among its peers. Samples treated with the polymer having the lowest glass transition temperature revealed a more compression index (i.e., obtained from odometer tests) and lower unconfined compressive strength. It is also observed that the swelling index and swelling pressure decreased marginally with increasing the glass transition temperature. [ABSTRACT FROM AUTHOR]

In recent years, the use of helical piles as a deep foundation option for structures has increased dramatically because they offer definite advantages over other solutions. The present study undertook a comprehensive investigation of the axial compressive behavior of helical piles in both sandy and clayey types of soil using finite element (FE) modeling. Since the helices of helical piles are more likely to disturb the soil adjacent to the pile, first some approaches are proposed to consider the effect of soil disturbance during a helical pile installation in numerical models. The numerical models have been validated and calibrated through full-scale compressive loading results using the ABAQUS software. The validated numerical models were used to investigate the load transfer mechanism of a typical helical pile in different types of sandy and clayey soil, and the numerically obtained ultimate bearing capacities were compared with the theoretical ones. Based on the comparison, it was found that the theoretical procedure overpredicts the ultimate capacity of helical piles in medium and dense sand. Additionally, different geometrical aspects of a typical helical pile were investigated using FE modeling in order to employ perfect geometry for studying the compressive behavior of a helical pile group with a square grid arrangement. The results revealed that the shape of the block failure mechanism in clayey soil differs from that in sandy soil. The acquired shapes are used to suggest a theoretical method for calculating the ultimate bearing capacity of a helical pile group based on the block failure mechanism. [ABSTRACT FROM AUTHOR]

A generalized water retention curve (WRC) model in a wide suction range considering the initial void ratio is presented in this paper. Both capillary and adsorbed water in soil pores are considered. Based on the experimental results that the adsorbed water content w a is not dependent on the initial void ratio, a new degree of saturation equation of adsorbed water is established. Meanwhile, a new degree of saturation equation of capillary water at various initial void ratios is proposed with a void ratio-related expression of the air entry value. Compared to Lu's model, only one parameter b is introduced in the established model, which can be easily calibrated using WRCs under two initial void ratios. The measured WRC results of 5 soils are used to verify the proposed model in comparison with the other 3 widely used WRC models. The soil used in the model validation covers a wide range of soil types from sandy soil to clay soil, including clayey silty sand, sandy clay till, clayey silt, expansive soil and lateritic soil. The proposed model is well verified for its ability to describe soil water retention characteristics in a wide suction range at various initial void ratios. [ABSTRACT FROM AUTHOR]

This study is a part of an extended investigation that aims to clarify the nemastatic activity of two commercial formulations of resistance inducers; Bio-arc and Nemastrol against Meloidogyne incognita infected sugar-beet in vitro and in vivo. Generally, data indicate that the ability of all individuals of the stage juveniles to penetrate the roots and develop into the next stage with a shortage of the duration of the life cycle in sandy soil compared to clayey soil. The results showed that Nemastrol caused a significant reduction in the percentage of penetration of M. incognita at the second-stage juveniles. Bio-arc ranked the second one comparing to control in clayey and sandy soil. The duration of developmental four juvenile stages, as well as egg-laying females, have a clear reduction with Nemastrol in clayey and sandy soil more than Bioarc comparing to control. The length of the life cycle varies, as treatments by Nemastrol were longer than Bio-arc in clayey and sandy soil (2-24 and 9-24 days), respectively. Besides, Nemastrol showed a poor formation of irregular giant cells devoided from the cytoplasm and contained less number of nuclei. [ABSTRACT FROM AUTHOR]

Two field experiments were conducted to evaluate the effect of foliar application of salicylic acid (SA) on the growth, yield and quality characters of five sugar beet varieties (MARWA KWS, SUGAR KING, MiRAGE, DREEMAN and ESTORA KWS) under two types of soil in the two different locations in Nubaria and Sakha regions during 2018/2019 and 2019/2020 seasons. The experiments were conducted in split-split plot design in the three replications, where the main plots assigned by the two soil types (sandy soil in Nubaria and clay soil in Sakha), while the subplots were occupied by the three foliar application concentrations of SA (control, 1000 and 2000 ppm) and the five sugar beet varieties (Marwa kws, Sugar king, Mirage, Dreeman and Estora kws) were allocated randomly the sub-subplots. The results revealed that the foliar application of 2000 ppm SA significantly influenced the top fresh mass and root biomass of sugar beet plants. Conversely, the increasing concentration of SA led to significant differences in fresh mass, sugar yield, and sucrose % as well as purity % of sugar beet in both seasons. The Dreeman and Estora kws exhibited better performance in terms of root length under Nubaria conditions. The interaction effect between the three factors gave the maximum levels of increment for most of the studied characters, particularly for the cultivar ESTORA KWS. [ABSTRACT FROM AUTHOR]

In savannas, partitioning of below‐ground resources by depth could facilitate tree–grass coexistence and shape vegetation responses to changing rainfall patterns. However, most studies assessing tree versus grass root‐niche partitioning have focused on one or two sites, limiting generalization about how rainfall and soil conditions influence the degree of rooting overlap across environmental gradients.We used two complementary stable isotope techniques to quantify variation (a) in water uptake depths and (b) in fine‐root biomass distributions among dominant trees and grasses at eight semi‐arid savanna sites in Kruger National Park, South Africa. Sites were located on contrasting soil textures (clayey basaltic soils vs. sandy granitic soils) and paired along a gradient of mean annual rainfall.Soil texture predicted variation in mean water uptake depths and fine‐root allocation. While grasses maintained roots close to the surface and consistently used shallow water, trees on sandy soils distributed roots more evenly across soil depths and used deeper soil water, resulting in greater divergence between tree and grass rooting on sandy soils. Mean annual rainfall predicted some variation among sites in tree water uptake depth, but had a weaker influence on fine‐root allocation.Synthesis. Savanna trees overlapped more with shallow‐rooted grasses on clayey soils and were more distinct in their use of deeper soil layers on sandy soils, consistent with expected differences in infiltration and percolation. These differences, which could allow trees to escape grass competition more effectively on sandy soils, may explain observed differences in tree densities and rates of woody encroachment with soil texture. Differences in the degree of root‐niche separation could also drive heterogeneous responses of savanna vegetation to predicted shifts in the frequency and intensity of rainfall. [ABSTRACT FROM AUTHOR]

This study investigates the condition of commercial miscanthus fields, growers' concerns and reasons for growing the crop and also the modelling of a realistic commercial yield. Juvenile and mature Miscanthus × giganteus crops of varying age are surveyed in growers' fields across mid‐England. We record in‐field plant density counts and the morphology of crops of different ages. Mature crops thrive on both clay and sandy soils. Plants surveyed appear robust to drought, weeds and disease, the only vulnerability is rhizome condition when planting. Mature miscanthus planted pre‐2014 continues to develop, spreading into planting gaps and growing more tillers. In stands planted post‐2014, improved planting techniques reduce planting gaps and create a reasonably consistent planting density of 12,500 plants/ha. The main reason for growers' investment in miscanthus is not financial return, but relates to its low requirement for field operations, low maintenance cost and regeneration. This offers practical solutions for difficult field access and social acceptability near public places (related to spray operations and crop vandalism). Wildlife is abundant in these fields, largely undisturbed except for harvest. This contributes to the greening of agriculture; fields are also used for gamebird cover and educational tours. This crop is solving practical problems for growers while improving the environment. Observed yield data indicate gradual yield increase with crop age, a yield plateau but no yield decrease since 2006. In stands with low planting densities, yields plateau after 9 years. Surveyed yield data are used to parameterize the MiscanFor bioenergy model. This produces options to simulate either juvenile yields or a yield for a landscape containing different aged crops. For mature English crop yields of 12 t ha−1 year−1, second‐ and third‐year juvenile harvests average 7 t ha−1 year−1 and a surrounding 10 km by 10 km area of distributed crop age would average 9 t ha−1 year−1. [ABSTRACT FROM AUTHOR]

• Agroforestry complexity and soil texture influence ecosystem service provision. • P and Ca cycling through litter and stable soil carbon stocks are synergistic. • Sandy soils are most suited for complex agroforestry. • Agroforestry Complexity Index encompassing diversity, density and management. Agroforestry systems are often promoted as solutions to address land degradation and climate change. However, agroforestry is an umbrella term for a large variety of systems and it is not clear how their degree of complexity influences their provision of soil-based ecosystem services, such as soil organic carbon (SOC) storage and nutrient cycling. Furthermore, a knowledge gap remains whether agroforestry systems perform equally well on all soil types. The objectives of this study were 1) to assess the links between agroforestry complexity, nutrient cycling and SOC fractions, and 2) to assess how soil texture influences these relationships in Brazilian agroforestry systems. We sampled 59 agroforestry plots across 30 sites in Sao Paulo state, Brazil, and 8 monocrop sites (6 pastures and 2 crop monocultures). The 38 sites represented a soil textural gradient, ranging from very sandy to very clayey (clay content range 25 – 620 g kg−1). An Agroforestry Complexity Index (ACI) was defined based on tree species richness, stem density and pruning management. Nutrient (N, P, K, Ca, Mg) and C contents were determined in litter and soil (0–30 cm depth) samples, and mineral-associated organic C (MAOC) and particulate organic C (POC) in soil samples were assessed as well. ACI was positively associated with C, N, P, Ca and Mg stocks in litter, and these litter nutrients were in turn positively associated with the corresponding soil nutrient stocks. Associations between soil nutrients and MAOC were stronger on sandy soils than on clayey soils, particularly for P, Ca and Cation Exchange Capacity (CEC). For POC, robust relationships with nutrients were only found on sandy soils. Structural Equation Models indicated causal relationships between agroforestry complexity, P and Ca cycling, and MAOC and POC stocks in topsoils. Our results indicate that nutrients effectively cycle from in situ mulch into plant-available soil pools and highlight the synergies between nutrient cycling and stable C stocks that can be achieved in complex agroforestry systems. These synergies seem to be particularly strong on sandy soils (<15 % clay). [ABSTRACT FROM AUTHOR]

The use of pre-emergent herbicides with prolonged residual effect on the soilis one of the factors that provide great efficiency in the control of the weeds. This study objected to evaluate the residual activity of the formulated mixture diuron + hexazinone + sulfometuron-methyl in different doses in soils of sandy and clayey textures. Two experiments were realized out, one for each soil, adopting the factorial scheme 2 x 8 + 1 with three repetitions. Two doses (0.605 + 0.170 + 0.014 and 1.072.07 + 0.302 + 0.025 kg ha-1 of diuron + hexazinone + respectively) at eight times (0, 20, 40, 60, 80, 100, 120 and 140 days, between the application of the formulated mixture and the bioindicator sowing) and another control without application. At 20 and 40 days after sowing of the bioindicator Cucumis sativus, phytotoxification was carried out. Using the non-linear log-logistic model, the t1/2 of the formulated mixture was determined for the two soils studied. In the soil of clay texture, t1/2 of 101 days was obtained, while for the sandy soil the t1/2 of the formulated mixture was of 52 days, for both doses. The prolonged residual effect on clayey soils may be an essential tool in the management of weeds in sugarcane. However, in sandy soils, smaller doses should be used because of the lower residual effect of the mixture and, consequently, avoid environmental contamination. [ABSTRACT FROM AUTHOR]

One of the most damaging species in sunflower crops in Brazil is the hairy beggartick (Bidens pilosa L). The large number of seeds, the various vegetative cycles during the year, the staggered germination and the scarcity of selective and effective herbicides to control this weed in sunflower are some of attributes that hinder the control of hairy beggartick populations. Two experiments were carried out to evaluate the control of hairy beggarticks, as well as sunflower tolerance to herbicides. The treatments were as follows: S-metolachlor (1,200 and 2,400 g ai ha-1), flumioxazin (60 and 120 g ai ha-1), and sulfentrazone (150 and 300 g ai ha-1) and two controls (weedy and weed-free check). The selectivity of the herbicides was higher at low doses. Flumioxazin and sulfentrazone caused injury to sunflowers at the highest doses and mainly in sandy soils. Although S-metolachlor did not cause visual symptoms of injury, the higher dose reduced sunflower yield. The herbicides sulfentrazone and flumioxazin provided satisfactory control of hairy beggartick plants in both types of soils. S-metolachlor presented medium control of hairy beggarticks in clay soil; however, its efficiency was slightly higher when applied in sandy soil. The most efficient herbicide for controlling hairy beggartick plants was flumioxazin, followed by sulfentrazone. [ABSTRACT FROM AUTHOR]

This paper presents the influence of temperature on the residual strength by analyzing shearing tests carried out in a temperature- and velocity-controlled ring shear apparatus. Temperature was applied in steps of cooling and heating ranging between 6 °C and 50 °C at a constant shearing velocity of 0.442 mm/min. Additional tests include the evaluation of the strength at 0.890 mm/min before and after the imposed temperature change. Six basic soil types characterized by different mineralogy, grain size and plasticity, as well as, mixture soils having different proportions of sand and clay, are evaluated and the results are interpreted in terms of their properties. The experimental results reveal that the temperature effect becomes relevant when fine particles and plasticity increase being negligible in the case of the sandy soil. Shear strength reacts immediately to temperature changes and a new residual strength establishes soon. The temperature effect is symmetric. An increase in temperature leads to a decrease in strength, and an equal and opposite trend is observed when temperature decreases. The magnitude of the strength variation is significant in clayey soils. For the case of high plasticity soils, the residual friction angle variation observed during cooling and heating (±50 °C) is around 2°. The strain rate effect evaluated in a smaller number of tests indicated a strain rate strengthening in all the materials tested except for the case of the sandy soil, which also was not reactive to temperature changes. The experiments are calibrated with a velocity, state, and temperature-dependent friction model. • Influence of temperature on residual shear strength have been characterized. • Heating leads to decrease in friction and cooling leads to an increase for high shearing rates. • Relevance of residual friction change with respect of temperature correlates with the soil plasticity. • No effect of temperature was measured for the clean sand tested. • The friction constitutive model developed by Chester (1994) can reproduce the tests performed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Soil sampling methods were assessed using 720 samples at two locations. • Calculated composite sampling decreased significant effects especially in sandy soils. • Sampling in-row resulted in greater crop effect on research results. • Soil enzyme activities required more samples compared to other soil properties. • A Monte Carlo simulation can be used to estimate needed sample size. A wide variety of soil sampling methods have been adopted, yet limited research has addressed how sampling methods can impact research results particularly for spatially variable soil properties. To address these concerns, we intensively sampled two existing soil health trials in Texas for analysis of soil extracellular enzymatic activities (EEAs), permanganate oxidizable C (POXC), soil organic C (SOC), and pH. The data generated was used to quantify the effect of composite sampling, sampling position (in-row vs between-row), and number of samples on statistical results. We compared a Monte Carlo simulation approach with a traditional power analysis to quantify the impact of the number of samples on our results. Calculated composite sampling resulted in lower statistically significant results compared to discrete sampling, demonstrating lower sensitivity of composite sampling. Sampling in-row resulted in greater values specifically for EEAs, pH, POXC, and SOC. Simulation generated estimated number of samples were mainly driven by the effect size and spatial variation. EEAs were highly variable, resulting in a higher estimated number of samples as compared to other soil properties such as POXC and SOC. In our study with two sites, soil with greater clay content resulted in overall lower estimated number of samples compared to a relatively sandy soil, demonstrating a greater sampling requirement for sandy soil. The simulation approach had a weak correlation with traditional power analysis. The simulation predicted lower estimated number of samples when compared to power analysis, which can help save cost in the long run. Overall, factors like composite sampling, sampling in-row vs between-row, and number of samples taken did impact research results. The impact of these sampling strategies on soil parameters of interest needs to be investigated to achieve the most accurate research results in soil science. [ABSTRACT FROM AUTHOR]

Emissions of greenhouse gases (GHGs), such as carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) have great impact on global warming and atmospheric chemistry. Biochar addition is a potential option for reducing GHGs emissions through carbon (C) sequestration and N 2 O mitigation. However, the influences of biochar on C and nitrogen (N) transformations in soil are still unclear, resulting in a poor understanding of the mechanisms of N 2 O mitigation effects of biochar. Here we carried out two soil incubation experiments to investigate the influence of two common biochars addition (corn cob and olive pulp) with ammonium sulfate on CO 2 and N 2 O emissions from two contrasting soil types (acidic sandy and alkaline clay soil). Furthermore, four extracellular enzymes activities that related to C and N cycling, i.e. cellobiohydrolase, chitinase, xylanase and β-glucosidase, were analyzed to gain insights into the underlying mechanisms of biochar’s effects on CO 2 and N 2 O evolutions. Contrasting effects of two biochars on CO 2 and N 2 O emissions were observed in the two different soils. The corn biochar addition had no significant effect on CO 2 and N 2 O emissions in the alkaline clay soil, but significantly decreased CO 2 emissions by 11.8% and N 2 O emissions by 26.9% in the acidic sandy soil compared to N-fertilizer only treatment. In contrast, olive biochar addition showed no significant effect on CO 2 emissions but decreased N 2 O emissions by 34.3% in the alkaline clay soil, while in the acidic sandy soil addition of olive biochar triggered about a twofold higher maximum CO 2 emission rate and decreased N 2 O emissions by 68.4%. Up to 50–130% higher specific CO 2 emissions (per unit of C-related enzyme activity: cellobiohydrolase, chitinases and β-glucosidase) were observed after addition of olive biochar compared to corn biochar addition in the acidic sandy soil. We concluded that biochar’s effects on N 2 O and CO 2 emissions are more pronounced in acidic soils. Alkaline biochar’s N 2 O mitigation potential in acidic soils seems to be dependent on soil NO 3 − content as drastically higher N 2 O emissions were measured in early phase of the experiment (where soil NO 3 − was high) and significantly lower N 2 O fluxes were obtained in later phases (with lower soil NO 3 − content). [ABSTRACT FROM AUTHOR]

• Thermal conductivity for frozen soil is higher than that of unfrozen soil. • Higher thermal conductivity of frozen and unfrozen soils at higher clay content. • Current models cannot predict correctly thermal conductivity of frozen sandy soil. Thermal conductivities of five sandy soils subjected to freezing-thawing and drying-wetting cycles were determined. Specimens were prepared at five different clay contents of 0, 5, 10, 15, 20% prior to compaction at the Proctor maximum dry density. Soil specimens were saturated prior to freezing-thawing and drying-wetting experiments. During a freezing-thawing cycle, soil's thermal conductivity and unfrozen water content were measured at different temperatures ranging from -3 °C to 0 °C. During a drying-wetting cycle, soil's thermal conductivity was measured at different water contents. The experimental results were then compared with predictions by two of the most appropriate existing models, namely De Vries's and Johansen's models, in order to provide insights into the effects of clay content on soil thermal conductivity at (saturated and unsaturated) unfrozen and frozen states. [ABSTRACT FROM AUTHOR]

Theoretical curves for different values of HT ht , 0.6, 0.8, and 1.0 are superimposed on the graph and can be seen to encapsulate the data. Yet, even without these separate curves, Wroth ([14]) noted that the parameter HT ht would track well with I ' i alone according to CSSM, and recommended the approximation HT ht (5) Graph: Fig. [Extracted from the article]

Recent research into the behaviour of soils has shown that it is in fact much more complex than can be described by the mechanics of saturated soils. Nowadays the trend of investigations has shifted towards the unsaturated state. Despite the significant progress that has been made so far, there are still a lot of unanswered questions related to the behaviour of unsaturated soils. For this reason, in the field of geotechnics some new concepts are developed, which include the study of soil suction. Most research into soil suction has involved clayey and silty material, whereas up until recently no data have been available about measurements in very stiff preconsolidated sandy silt. Very stiff preconsolidated sandy silt is typical of the Krško Basin, where it is planned that some very important geotechnical structures will be built, so that knowledge about the behaviour of such soils at increased or decreased water content is essential. Several different methods can be used for soil suction measurements. In the paper the results of measurements carried out on very stiff preconsolidated sandy silt in a Bishop - Wesley double-walled triaxial cell are presented and compared with the results of soil suction measurements performed by means of a potentiometer (WP4C). All the measurement results were evaluated taking into account already known results given in the literature, using the three most commonly used mathematical models. Until now a lot of papers dealing with suction measurements in normal consolidated and preconsolidated clay have been published. Measurements on very stiff preconsolidated sandy silt, as presented in this paper were not supported before. [ABSTRACT FROM AUTHOR]

Heavy metal contaminated soils pose a serious threat to the environment, and preparing ceramsite using contaminated soils was proposed as an effective method to address this threat in this study. Specifically, two typical soils (i.e., contaminated clay and sandy soil) were mixed with different ratios and calcined at temperature 1000–1200 °C to prepare ceramsite. Special attentions were paid to evaluating the immobilization of heavy metals in ceramsite and identifying the corresponding immobilization mechanisms. Using the leachability of heavy metals from ceramsite as evaluation criteria, the optimum mixing ratio of clay/sandy soil and sintering temperature were determined as 0.6:0.4 and 1200 °C. Moreover, based on the spectroscopic characterizations and thermodynamic calculation, high sintering temperature well facilitated the liquid phases formation, promoting the reactions between heavy metals and aluminosilicates and the valence state conversion of heavy metals. Accordingly, heavy metals were well immobilized in ceramsite by forming thermodynamically stable minerals, being encapsulated in solid matrix, and transforming to valence states with low mobility. The leaching conditions including pH and temperature had minimal effect on the immobilization of heavy metals in ceramsite. In summary, ceramsite prepared by contaminated soils was environmentally friendly and had good potential in engineering application as building materials. [Display omitted] • Co-utilization of polluted clay and sandy soil for ceramsite production is presented. • The optimum ratio of clay/sandy soil and sintering temperature are 0.6:0.4 and 1200 °C. • The immobilization effectiveness of heavy metals in ceramsite is evaluated. • The immobilization mechanism of heavy metals in ceramsite is determined. [ABSTRACT FROM AUTHOR]

The permanent deformation of the road subgrade soil accumulated during passage of the cyclic loads is mainly due to the post-compacting and plastic flow mechanisms according to a study by the National Cooperative Highway Research Program in 2004. The main objective of the paper is to develop a relationship between the parameters a an d b of a power model and the usual physical properties of subgrade soils. The parameters a and b are assumed to represent the post-compacting and plastic deformation, respectively. Highlighting the link between the parameters a and b and the mechanisms of permanent deformation was the basic assumption which helped developing correlations. Data collected on nine different samples of soils characterized and having undergone cyclic triaxial tests permanent deformation were used to develop relationships. A distinction was made between the relationship parameter for clay and sandy soils. Indeed, clay soils with lower air permeabilities behave differently when compared to post-compaction sandy soils. However, a single relationship was developed for the parameter b, because the observed behavior appears similar for clay and sandy soils. Both correlations have coefficients of determination about 0.6. Also, comparison of the measured and predicted permanent deformation was done on the clay of St-Narcisse and sand of Fossambault. The results are generally good, despite a case of discrepancy observed. [ABSTRACT FROM AUTHOR]

Sandy soils are well known as being droughty, erodible, infertile and non economical. The main objective is to vegetate the desert with a water consumption as low as possible. Two field experiments were conducted during 2012/2013 and 2013/2014 seasons. The experiments were carried out in Developing Agricultural System Project, Sinai Station, Sinai Governorate to study the effect of' nanoclay flakes treatments on revegetation of sandy soil under sprinkler irrigation system with Egyptian clover var Gemmiza 1. The experiments were designed as a split-plot design with four replications, the main plots included the source of irrigation dates after 3, 5, 7 and 9 days, the subplot had nanoclay doses (0, 8.5, 17 and 25 kg/plot) at soil depth 10 cm. The results indicated that the water requirement for the Egyptian clover ranged from 2800- 3000 m3/fed of water depending on climate and the growing period, Evaportranspiration increases from establishment of flowering stage (5-7mm/day), the irrigation interval of 7 days showed the highest forage yield, the dose of 17Kg/plot nanoclay flakes had significant effect on forage yield. Also, the obtained results revealed that yield components have been increased due to the nanoclay treatment with high significancy compared to the untreated area by increasing the availability of water for crop use by 50%. Treating the sandy soil with clay nano flakes resulted in significant differences in Egyptian clover yield and led to increasing the nitrogen, phosphorus, potassium, contents and decreasing the water consumption rate by 50%. [ABSTRACT FROM AUTHOR]

The objective of this investigation was to define the zoning of soil liquefaction potential for the Guillermón Moncada Popular Council in the municipality of Santiago de Cuba. The engineering and geological conditions and seismic peculiarities favoring a seism to take place were assessed. The safety factor was re-calculated after determining possible maximum intensity values based on seismic magnitudes that can trigger the soil of the investigated area to liquefy. A scheme of the area's soil susceptibility to liquefaction was obtained. Based on this result, it was concluded that the sectors that are most likely to experience soil liquefaction if an earthquake of magnitudes ranging between 7,75 and 8 occurs are located towards the center-east of the Popular Council with sandy-clayey soils being predominant. This information is very useful for the location and planning of engineering construction works in the area. [ABSTRACT FROM AUTHOR]

The genus Aneura is represented in Poland by two species - A. pinguis and A. maxima. A. pinguis in contrast to A. maxima is a complex of cryptic species temporarily named A. pinguis species: A, B, C, and E. All species of the A. pinguis complex and A. maxima differ in their geographic distribution and habitat preferences. A. pinguis species A grows mainly on humus over limestone rocks in the Western Carpathians, A. pinguis species B occurs mainly on clay soil in Bieszczady Mts. and in clayish areas of lowlands, A. pinguis species C grows both in lowlands and mountains and it occupies mostly wet sandy soils, on the shores of oligotrophic lakes and river and mountain stream banks, A. pinguis species E is connected with calcareous rocks in flowing water in mountains. A. maxima grows over the country - both in lowlands and mountains, in marshes situated on the river banks. [ABSTRACT FROM AUTHOR]

Crude oil products are among the most common pollutants of soils which can drastically affect the engineering properties of soils. In the current study, a series of laboratory tests were conducted to investigate the interaction between crude oil and sandy soil with clay and the effect of crude oil, crude oil residence time, absorbent additives type and content, microwave power, specimen weight, maximum grain size and fine grain fraction on the removal efficiency of pollution through microwave radiation to extract optimum values for potential and high efficiency in hydrocarbon removal. The present study also investigated geotechnical properties, including cohesion, internal friction angle, shear strength in three conditions before and during pollution and after cleanup utilizing direct shear and static triaxial tests. The results showed that the presence of clay particles, oil content and saturation effect in the soil could significantly control the engineering soil behavior. In the presence of 4% crude oil in direct shear tests, the whole oil content is accumulated on clay particles due to the high specific area of clay particles, reducing the cohesion and the internal friction angle. By contrast, beyond the 4% of crude oil, sand particle in the soil was the controlling factor of the whole behavior of the mixture. In triaxial tests, the trend of soil parameters is almost similar to direct shear tests by increasing crude oil, except that, with an increase of 4% of oil, the friction angle of the soil increases due to the presence of a large number of flocculated clay particles. • Microwave heating was considered as a potential option to remediate the polluted soil. • The highest removal efficiency was obtained from effective microwave parameters. • Soil strength parameters were evaluated before, during and after cleanup. • Clay particles, oil and water in the soil control the polluted soil behavior. [ABSTRACT FROM AUTHOR]

Compensation grouting is often employed as a mitigation technique to reduce the settlements induced by tunneling. The efficiency of compensation grouting, defined as the ratio of the volume of heave induced at the ground surface to the volume of injected grout, is strongly dependent on grout properties, injection characteristics, and soil properties. In clayey soils, site observations and laboratory tests show high values of compensation efficiency immediately after injection. However, the efficiency can decrease with time if positive excess pore-water pressures develop in the soil during the injection process. Conversely, in sandy soils, a loss of volume occurs because of pressure filtration of the grout during and soon after the injection process, which reduces the compensation efficiency. This paper describes an analytical model that can be used to evaluate the volume loss produced by pressure filtration of cement-bentonite grouts as a function of soil, grout, and injection parameters. The magnitude of pressure filtration is evaluated as the grout efficiency, which is given by the ratio of the volumes of the final grout body to the injected grout. Results show that the grout efficiency increases with decreasing soil permeability and with increasing grout bentonite content. The result of a grout injection test on a silty soil is back-analyzed using this approach in which the grout efficiency is first evaluated through the proposed filtration model and then used to calibrate a numerical simulation of the test. The good agreement between experimental data and computed results shows that prediction of the efficiency of compensation grouting can be improved using the proposed approach. [ABSTRACT FROM AUTHOR]

The addition of clay to lime-amended biosolids has been proposed as a soil amendment (LaBC) for remediating acidic-sandy soil. We investigated whether the presence of clay in LaBC altered soil microbial processes over a 30-week period. Aerobic-incubation and CO respiration assays were used to monitor water repellence and chemical and microbiological properties of amended soil. Dry LaBC was applied at equivalent wet weight of 50, 100 and 150 t ha. In addition, dry components of LaBC (lime, clay, lime + clay (LAC) and lime + biosolids (LAB)) were applied separately at rates equivalent to their fractions within LaBC. Inclusion of clay in LaBC was effective in eliminating water repellence at all application rates. Inclusion of clay in LaBC decreased nitrogen (N) release from the biosolids (by 58 %), even at 50 t ha, but only during the first 2 weeks of incubation. LaBC consistently decreased soil microbial respiration compared with LAB alone when applied at 150 t ha thereby protecting organic matter decomposition. There was no significant N release with lime and clay amendment alone or in combination (LAC) in the absence of the biosolids. There may be a complex interaction between clay, lime and organic matter, but each may have had a role in altering N release from biosolids at different times during the 30-week incubation. Addition of clay to LAB increased its effectiveness in remediating this water-repellent, acidic-sandy soil and prolonged the N release from the biosolids following soil amendment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Biogas residues and cattle slurry shifted bacterial community in sandy, clay and organic soils. [•] Biogas residues and cattle slurry reduced substrate-induced respiration in organic soil. [•] Biogas residues and cattle slurry affected soil microbial system, differently. [ABSTRACT FROM AUTHOR]

137Cs is one of the most persistent radioactive contaminants in soil after a nuclear accident. It can be taken up by plants and enter the human food chain generating a potential human health hazard. Although a large amount of literature has highlighted the role of the different processes involved in Cs uptake by plants, there is still no simple way to predict its transfer for a specific plant from a particular soil. Based on the assumption that the concentration ratio (CR) of Cs can be predicted from one plant taxon if the CR of another taxon is known and taken as reference, whatever the supporting soils, a series of plant/soil Cs transfer experiments were performed on Rhizotest during 21 days using three soils with different textures, clay and organic matter contents and two plants (millet and mustard) with potentially contrasting Cs uptake capacity based on their phylogeny. CRs of each plant varied by 2–3 orders of magnitude depending on the soil and contrary to expectations, the CRs of mustard were either higher (for clay soil), equal (for clay-loam soil) or lower (for sandy soil) than the one of millet. Considering Cs availability in soils and defining a new CR based on the amount of Cs available in the soil (CR avail) decreased the range of variation in CR between the different soil types for a given plant by one order of magnitude. Differences in Cs (and K) translocation to shoots, possibly specific to millet within Poales, could partly explain the relative CRs of millet and mustard as a function of soils. • Soil/plant Cs transfer experiments on Rhizotests with three soils and two plants. • The Cs CR of mustard is not always the highest, contrary to plant phylogeny predictions. • Differences in CRs may partly relate to the translocation capacities of millet. • Calculating CR based on the available Cs pool in soils reduce the range of CR variation. [ABSTRACT FROM AUTHOR]

This paper proposes a combined-loading elastoplastic constitutive model (CL model) for a unified description of the mechanical behavior of soil materials, including clay, sand, and intermediate soil. This mathematical model combines the super-subloading yield surface Cam-clay model and the non-associated Drucker–Prager (DP) model. The first model introduces the skeleton soil structure concept into the Cam-clay model based on critical-state soil mechanics. It describes the mechanical behavior of naturally deposited clay more accurately than the existing model does. The non-associated DP model considers the frictional properties of granular materials and is widely used to describe the undrained shear behavior, particularly that of sandy soil. The newly proposed model is one in which these two independently existing models simultaneously or independently work in loading states according to the loading criterion, which can be derived as a natural result from plastic multipliers. This framework allows for a unified description of a wide range of soil materials, including naturally deposited clayey soils and sandy soils. [ABSTRACT FROM AUTHOR]

Abstract: We determined the effects of nitrification capacity and environmental factors on landfill methane oxidation potential (MOP) using an aged refuse in laboratory batch assays and compared it with two different types of soils. The nitrogen conversion in the three experimental materials after 120 h incubation yielded first-order reaction kinetics at an initial concentration of 200 mg kg−1 NH4 +–N. The net nitrification rate for the aged refuse was 1.50 (p < 0.05) and 2.08 (p < 0.05) times that of the clay soil and the sandy soil, respectively. The net NO3 −–N generation rate by the aged refuse was 1.93 (p < 0.05) and 2.57 (p < 0.05) times that of the clay soil and the sandy soil, respectively. When facilitated by ammonia-oxidizing bacteria during CH4 co-oxidation, the average value of the MOP in the aged refuse at a temperature range of 4–45 °C was 2.34 (p < 0.01) and 4.71 (p < 0.05) times greater than that of the clay soil and the sandy soil, respectively. When the moisture content ranged from 8 to 32% by mass, the average values for the MOP in the aged refuse were 2.08 (p < 0.01) and 3.15 (p < 0.01) times greater than that of the clay soil and the sandy soil, respectively. The N2O fluxes in the aged refuse at 32% moisture content were 5.33 (p < 0.05) and 12.00 (p < 0.05) times more than in the clay and the sandy soil, respectively. The increase in N2O emissions from a municipal solid waste landfill can be neglected after applying an aged refuse bio-cover because of the much higher MOP in the aged refuse. The calculated maximum MOP value in the aged refuse was 12.45 μmol g−1 d.w. h−1, which was much higher than the documented data. [Copyright &y& Elsevier]

Plant availability and risk for leaching and/or runoff losses of phosphorus (P) from soils depend among others on P concentration in the soil solution. Water-soluble P in soil measures soil solution P concentration. The aim of this study was to understand the effect of wheat residue char (biochar) addition on water-soluble P concentration in a wide range of biochar-amended soils. Eleven agricultural fields representing dominant soil texture classes of Swedish agricultural lands were chosen. Concentrations of water-soluble P in the soils and in biochar were measured prior to biochar incorporation to soils in the laboratory. Experiments with three dominant soil textures-silt loam, clay loam, and an intermediate loam soil with different rates of biochar addition (i.e., 0.5, 1, 2, and 4 %; w/ w) showed that the highest concentration of water-soluble P was achieved at an application rate of 1 %. At higher application rates, P concentrations decreased which coincided with a pH increase of 0.3-0.7 units. When the 11 soils were amended with 1 % ( w/ w) biochar, water-soluble P concentrations increased in most of the soils ranging from 11 to 253 %. However, much of the water-soluble P added through the biochar was retained (33-100 %). We concluded that wheat residue char can act as a source of soluble P, and low and high additions of biochar can have different effects on soil solution P concentration due to possible reactions with Ca and Mg added with biochar. [ABSTRACT FROM AUTHOR]