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1
Várallyay, Gy. "Soil-water stress". Cereal Research Communications 37, n. 2 (giugno 2009): 315–19. http://dx.doi.org/10.1556/crc.37.2009.suppl.7.
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Keller, T., J. Arvidsson, J. B. Dawidowski e A. J. Koolen. "Soil precompression stress". Soil and Tillage Research 77, n. 1 (maggio 2004): 97–108. http://dx.doi.org/10.1016/j.still.2003.11.003.
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Arvidsson, J., e T. Keller. "Soil precompression stress". Soil and Tillage Research 77, n. 1 (maggio 2004): 85–95. http://dx.doi.org/10.1016/j.still.2004.01.003.
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Xu, Bin Bin. "Influence of Soil Structure on the Mechanical Response of Soft Soil". E3S Web of Conferences 38 (2018): 03027. http://dx.doi.org/10.1051/e3sconf/20183803027.
Testo completoAbstract (sommario):
Usually the natural sedimentary soils possess structure more or less, which makes their mechanical response much different from the fully remolded soils. In this paper, the influence of soil structure on the mechanical response such as compressibility, shear, permeability is literately reviewed. It is found that the compressibility and consolidation behavior of structured and remolded soils can be divided clearly before or after the structural yield stress. The stress-strain relationship can be divided into two segments before and after the structural yield stress. Before the yield stress, the curve is elevating and after the yield stress the curve is decreasing. The increasing rate of pore water pressure increases after the soil reached yield stress.
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Richards, BG. "The role of lateral stresses on soil water relations in swelling clays". Soil Research 24, n. 4 (1986): 457. http://dx.doi.org/10.1071/sr9860457.
Testo completoAbstract (sommario):
The moisture characteristic of a swelling soil is the result of complex interaction between the soil water potential and imposed mechanical stresses. This can give rise to soil water profiles which cannot be interpreted by soil water theories for non-swelling soils. Agricultural soil physics has been concerned primarily with highly structured surface soils, and has developed simple theories for the effects of stress on soil water relations in swelling soils. These simple theories ignore the effect of lateral stress in the soil. Civil engineers, on the other hand, dealing mainly with less complex soils at depth, have developed more complex theories for the effect of three-dimensional stress states on soil water relations. This paper shows how the effect of three-dimensional stress can and should be included in soil water studies of swelling soils, and gives examples to demonstrate the possible magnitude of such effects.
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Shevchenko, A. V., I. G. Budzanivska, T. P. Shevchenko e V. P. Polischuk. "Stress caused by plant virus infection in presence of heavy metals". Plant Protection Science 38, SI 2 - 6th Conf EFPP 2002 (31 dicembre 2017): 455–57. http://dx.doi.org/10.17221/10522-pps.
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Due to increased heavy metal content in Ukrainian soils, purpose of the work was to study relations between presence of heavy metals in soil and their effect on development of phytoviral infection. Experiments were conducted in Nicotiana tabacum – Potato virus X model system. Soluble salts of Cu, Zn and Pb were deposited in soil separately at the limiting concentrations simultaneously with virus infection of plants. Infected plants grown on usual soil showed symptoms of disease on 16 dpi as well as plants grown on soil with metals deposited. Contrary, combined effect of heavy metals and virus infection caused an increase of chlorophyll content comparing with control plants, therefore effect of heavy metals partially compensated the effect of virus infection on experimental plants.
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Gao, Xiaojing, Qiusheng Wang, Chongbang Xu e Ruilin Su. "Experimental Study on Critical Shear Stress of Cohesive Soils and Soil Mixtures". Transactions of the ASABE 64, n. 2 (2021): 587–600. http://dx.doi.org/10.13031/trans.14065.
Testo completoAbstract (sommario):
HighlightsErosion tests were performed to study the critical shear stress of cohesive soils and soil mixtures.Linear relationships were observed between critical shear stress and cohesion of cohesive soils.Mixture critical shear stress relates to noncohesive particle size and cohesive soil erodibility.A formula for calculating the critical shear stress of soil mixtures is proposed and verified.Abstract. The incipient motion of soil is an important engineering property that impacts reservoir sedimentation, stable channel design, river bed degradation, and dam breach. Due to numerous factors influencing the erodibility parameters, the study of critical shear stress (tc) of cohesive soils and soil mixtures is still far from mature. In this study, erosion experiments were conducted to investigate the influence of soil properties on the tc of remolded cohesive soils and cohesive and noncohesive soil mixtures with mud contents varying from 0% to 100% using an erosion function apparatus (EFA). For cohesive soils, direct linear relationships were observed between tc and cohesion (c). The critical shear stress for soil mixture (tcm) erosion increased monotonically with an increase in mud content (pm). The median diameter of noncohesive soil (Ds), the void ratio (e), and the organic content of cohesive soil also influenced tcm. A formula for calculating tcm considering the effect of pm and the tc of noncohesive soil and pure mud was developed. The proposed formula was validated using experimental data from the present and previous research, and it can reproduce the variation of tcm for reconstituted soil mixtures. To use the proposed formula to predict the tcm for artificial engineering problems, experimental erosion tests should be performed. Future research should further test the proposed formula based on additional experimental data. Keywords: Cohesive and noncohesive soil mixture, Critical shear stress, Erodibility, Mud content, Soil property.
8
Wang, Dong Lin. "Experimental Study on Soil Water Characteristic Curve of Compacted Unsaturated Soil". Advanced Materials Research 168-170 (dicembre 2010): 1285–88. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1285.
Testo completoAbstract (sommario):
Soil water characteristic curve is one of important topics of unsaturated soils. Pressure plate extractor and GDS unsaturated triaxial apparatus are used to study influencing factors including types of soils and net mean stress. Through method of least-squares, Fredlund five-parameter model were employed to fit soil-water characteristic curves. The results show that model provided a satisfactory fit to the experimental data. Through an analysis of influencing factors, we find that not only physical condition of samples but also external stress condition can affect the shape of soil water characteristic curve.
9
Lukács, A., G. Pártay, T. Németh, S. Csorba e C. Farkas. "Drought stress tolerance of two wheat genotypes". Soil and Water Research 3, Special Issue No. 1 (30 giugno 2008): S95—S104. http://dx.doi.org/10.17221/10/2008-swr.
Testo completoAbstract (sommario):
Biotic and abiotic stress effects can limit the productivity of plants to great extent. In Hungary, drought is one of the most important constrains of biomass production, even at the present climatic conditions. The climate change scenarios, developed for the Carpathian basin for the nearest future predict further decrease in surface water resources. Consequently, it is essential to develop drought stress tolerant wheat genotypes to ensure sustainable and productive wheat production under changed climate conditions. The aim of the present study was to compare the stress tolerance of two winter wheat genotypes at two different scales. Soil water regime and development of plants, grown in a pot experiment and in large undisturbed soil columns were evaluated. The pot experiments were carried out in a climatic room in three replicates. GK Élet wheat genotype was planted in six, and Mv Emese in other six pots. Two pots were left without plant for evaporation studies. Based on the mass of the soil columns without plant the evaporation from the bare soil surface was calculated in order to distinguish the evaporation and the transpiration with appropriate precision. A complex stress diagnosis system was developed to monitor the water balance elements. ECH<sub>2</sub>O type capacitive soil moisture probes were installed in each of the pots to perform soil water content measurements four times a day. The irrigation demand was determined according to the hydrolimits, derived from soil hydrophysical properties. In case of both genotypes three plants were provided with the optimum water supply, while the other three ones were drought-stressed. In the undisturbed soil columns, the same wheat genotypes were sawn in one replicate. Similar watering strategy was applied. TDR soil moisture probes were installed in the soil at various depths to monitor changes in soil water content. In order to study the drought stress reaction of the wheat plants, microsensors of 1.6 mm diameter were implanted into the stems and connected to a quadrupole mass spectrometer for gas analysis. The stress status was indicated in the plants grown on partly non-irrigated soil columns by the lower CO<sub>2</sub> level at both genotypes. It was concluded that the developed stress diagnosis system could be used for soil water balance elements calculations. This enables more precise estimation of plant water consumption in order to evaluate the drought sensitivity of different wheat genotypes.
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Oh, Seboong, Ki Hun Park, Oh Kyun Kwon, Woo Jung Chung e Kyung Joon Shin. "On the Hypothesis of Effective Stress in Consolidation and Strength for Unsaturated Soils". Applied Mechanics and Materials 256-259 (dicembre 2012): 108–11. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.108.
Testo completoAbstract (sommario):
The hypothesis on effective stress of unsaturated soils is validated by consolidation strength results of triaxial tests for the compacted residual soil. The effective stress can describe the unsaturated soil behavior, which was defined from shear strength or from soil water characteristic curves. Since the effective stress from consolidation agrees with that from the shear strength, the effective stress from soil water retention curve could describe the unsaturated behavior consistently on both consolidation path and stress at failure. The effective stress can describe the entire unsaturated behavior from consolidation to failure.
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Handayani, Tri, e Kazuo Watanabe. "The combination of drought and heat stress has a greater effect on potato plants than single stresses". Plant, Soil and Environment 66, No. 4 (30 aprile 2020): 175–82. http://dx.doi.org/10.17221/126/2020-pse.
Testo completoAbstract (sommario):
Several research groups have examined the effects of drought stress and heat stress on potato, but few investigations of the effects of combined drought-heat stress have been reported. Using five potato lines, the potato plants’ responses to drought stress, heat stress, as well as combined drought-heat stress were studied, to get the insight in phenotypic shift due to abiotic stresses. The experiment was conducted as a growth room experimental under non-stress and abiotic stresses (drought, heat, and combined drought-heat) conditions. The results demonstrated that potato plants responded to the abiotic stresses by decreasing their plant height, leaf size, cell membrane stability, and relative water content (RWC). However, increasing their leaf chlorophyll content under drought and combined drought-heat stresses. Generally, the combined drought-heat stress had a greater effect on the tested traits. The potato line L1 (84.194.30) showed the lowest level of wilting in all three types of abiotic stress, supported by a small RWC change compared to the control condition; L1 is thus considered relatively tolerant to abiotic stress. The potato lines’ different responses to each type of abiotic stress indicate that the potato lines have different levels of sensitivity to each abiotic stress.
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Sultanov, Karim, Pavel Loginov, Sabida Ismoilova e Zulfiya Salikhova. "Wave processes in determining mechanical characteristics of soils". E3S Web of Conferences 97 (2019): 04009. http://dx.doi.org/10.1051/e3sconf/20199704009.
Testo completoAbstract (sommario):
Mechanical characteristics of soils under dynamic and static loads are determined in laboratory conditions on special devices. Dynamic loads in the devices are initiated by an impact on a soil sample. Under the impact the waves are initiated in soil; they significantly affect the stress-strain state of soil samples placed in the device. Depending on the parameters of the impact load in the device, in different sections of soil sample there arise the stress-strain states, different in quality and quantity. Mechanical characteristics of soil, determined by this stress-strain state, also differ. The effect of stress-strain state of soil on its mechanical characteristics can be estimated theoretically. The initiation of the wave process and dynamic stress-strain state in soil sample placed in the device can be theoretically examined in detail. In this regard, the wave problem is set, which corresponds to the statement of experiments on the device of dynamic loading of soil. The law of soil strain is taken as an elastic-viscoplastic one. Numerical solution of wave equations is obtained by the finite difference method. Based on the analysis of stress-strain state of soil in various sections, obtained by numerical calculations, the condition is derived under which the effect of wave processes on mechanical characteristics of soils is eliminated. This condition (formula) establishes the relationship between the wavelength, the velocity of wave propagation in soil, the thickness of the soil sample in the device and the duration of dynamic load.
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Randall K. Wood e Eddie C. Burt. "Soil-Tire Interface Stress Measurements". Transactions of the ASAE 30, n. 5 (1987): 1254–58. http://dx.doi.org/10.13031/2013.30554.
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Wigginton, N. S. "Global soil resources under stress". Science 348, n. 6235 (7 maggio 2015): 644–46. http://dx.doi.org/10.1126/science.348.6235.644-j.
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Rastija, M., V. Kovacevic, D. Rastija e D. Simic. "Manganese and zinc concentrations in maize genotypes grown on soils differing in acidity". Acta Agronomica Hungarica 58, n. 4 (1 dicembre 2010): 385–93. http://dx.doi.org/10.1556/aagr.58.2010.4.7.
Testo completoAbstract (sommario):
Drought and soil acidity are two major abiotic stress factors limiting maize production worldwide, generating imbalances in the manganese (Mn) and zinc (Zn) status in plants. This study was conducted to determine the effects of drought stress on the Mn and Zn status in maize genotypes grown on acid and non-acid soils and how the Mn and Zn status affects the changes in grain yield caused by drought stress and soil acidity. Seventeen genotypes were grown at two locations differing in soil acidity in Eastern Croatia in 2003 and 2004. Positive values of an aridity index indicated drought stress in 2003. The genotypes had much higher Mn and Zn concentrations on acid soil than on nonacid soil: more than twice as high in both seasons for Zn and about 6 and 9 times higher in normal and in dry seasons, respectively, for Mn. This demonstrates that drought combined with soil acidity led to the excessive accumulation of Mn in maize plants. However, variation was observed between the maize genotypes for the Mn accumulation on soils differing in acidity when drought occurred. Some genotypes accumulated Mn on acid soil irrespective of drought. The Mn and Zn status had no discernible effect on the changes in grain yield caused by drought stress and/or soil acidity.
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Liu, Wei Zheng, Jun Hui Zhang e Hao Zhang. "Analysis on Pile-Soil Stress Ratio of Composite Foundation with Sparse Capped-Piles under Lime-Soil Embankment Load". Applied Mechanics and Materials 501-504 (gennaio 2014): 124–31. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.124.
Testo completoAbstract (sommario):
The combined effect of the embankment fill, piles and caps, and foundation soils on the load transfer characteristics of sparse capped-piled embankment is very significant. Using the modified cylindrical shear stress transfer model based on Marston soil pressure theory, a new calculation method for pile-soil stress ratio of sparse rigid pile composite foundation incorporating the arching effect in lime-soil and soil-pile interaction was presented. The presented method is verified by comparison between analytical solutions and the observed results from a practical project. In addition, a parametric study was also conducted to evaluate the influence of the embankment height, the cohesion of fill and pile-soil stiffness ratio on the pile-soil stress ratio.
17
Shu, Rongjun, Lingwei Kong, Bingheng Liu e Juntao Wang. "Stress–Strain Strength Characteristics of Undisturbed Granite Residual Soil Considering Different Patterns of Variation of Mean Effective Stress". Applied Sciences 11, n. 4 (20 febbraio 2021): 1874. http://dx.doi.org/10.3390/app11041874.
Testo completoAbstract (sommario):
Granite residual soil is one of the most frequently encountered problem soils in tropical regions, whose mechanical behavior heavily depends on the pattern of variation of mean effective stress (p’) during shearing, which can be classified into three categories: increasing-p’, constant-p’, and decreasing-p’. Unfortunately, so far, the stress–strain strength characteristics of granite residual soils have been studied mainly under increasing-p’ stress paths, although it is very likely to encounter stress paths with decreasing p’ in practice, especially in excavation engineering. Moreover, most pertinent research has focused on remolded granite residual soils, whereas undisturbed specimens have not yet received enough attention. In this paper, stress path triaxial tests considering different patterns of variation of mean effective stress were conducted on an undisturbed granite residual soil. Subsequently, a variable termed loading angle was introduced to quantitatively represent stress path. The influences of stress path on the Mohr–Coulomb strength parameters, deformation characteristics, ductility, and shearing stiffness were analyzed, with an emphasis on the role of pattern of variation of mean effective stress. The experimental results show that friction angle of the soil increases while cohesion decreases with the increase in loading angle. The increase in loading angle leads to less volume contraction and smaller failure strain. During shearing, the soil exhibited a less brittle response under stress paths with smaller loading angles. The initial secant shear modulus first decreased and then increased as the loading angle increased, with the minimum shearing stiffness occurring at a certain loading angle lying between 90° and 123.7°.
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Nishimura, Tomoyoshi, Yasunari Hirabayashi, Delwyn G. Fredlund e Julian K.-M. Gan. "Influence of stress history on the strength parameters of an unsaturated statically compacted soil". Canadian Geotechnical Journal 36, n. 2 (25 settembre 1999): 251–61. http://dx.doi.org/10.1139/t98-098.
Testo completoAbstract (sommario):
Unsaturated soils are generally near the ground surface and are commonly overconsolidated due to environmental effects. The stress state variables for an unsaturated, in situ profile consist of the net total stress, (σ - ua), and matric suction, (ua - uw), where σ is the total stress (in three directions), ua is the pore-air pressure, and uw is the pore-water pressure. These stress state variables control the behavior of the unsaturated soil. A total stress ratio, TSR, was used in this study as a measure of the stress history. The total stress ratio is defined as the ratio of the compaction pressure to the current confining pressure. Shear tests were conducted using a modified direct shear apparatus on a statically compacted unsaturated soil subjected to various total stress ratios with controlled matric suction. The shear strength parameters (i.e., ϕ', ϕb, and c') for an unsaturated soil were measured using the modified direct shear apparatus. The total stress ratio influences the shear strength parameter ϕb of a compacted soil. The shear strength parameter ϕb decreases with matric suction regardless of the loading history. For a compacted soil with a total stress ratio of 1.0, ϕb was higher than that for the soil tested at a total stress ratio greater than 1.0, regardless of increase in matric suction, and was shown to be influenced by loading history.Key words: unsaturated soil, shear strength, stress history, compacted soil, direct shear test, matric suction.
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Bowen, Hayden J., e Misko Cubrinovski. "Effective stress analysis of piles in liquefiable soil". Bulletin of the New Zealand Society for Earthquake Engineering 41, n. 4 (31 dicembre 2008): 247–62. http://dx.doi.org/10.5459/bnzsee.41.4.247-262.
Testo completoAbstract (sommario):
When evaluating the seismic performance of pile foundations in liquefiable soils, it is critically important to estimate the effects of cyclic ground displacements on the pile response. Advanced analyses based on the effective stress principle account for these effects in great detail by simulating the process of pore pressure build-up and associated stress-strain behaviour of soils. For this reason, the effective stress method has been established as a principal tool for the analysis and assessment of seismic performance of important engineering structures.
In this paper, effective stress analysis is applied to a case study of a bridge pier founded on piles in liquefiable soil. The study examines the likely effects of liquefaction, cyclic ground displacements and soil-structure interaction on the bridge foundation during a strong earthquake. A fully coupled effective stress method of analysis is used to compute the dynamic response of the soil-pile-bridge system. In the analysis, an elastoplastic deformation law based on a state concept interpretation is used for modelling nonlinear behaviour of sand. The seismic performance of the pile foundation is discussed using computed time histories and maximum values of ground and pile displacements, excess pore water pressure and pile bending moments. The advantages of the effective stress analysis are discussed through comparisons with a more conventional pseudo-static analysis of piles.
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Huang, Hua, Min Huang e Jiangshu Ding. "Calculation of Tangent Modulus of Soils under Different Stress Paths". Mathematical Problems in Engineering 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/1916761.
Testo completoAbstract (sommario):
During excavation of foundation pit, soils of different sites may undergo different unloading paths. This study focuses on the tangent modulus of soil under different stress paths and provides theoretical basis for the deformation calculation of soil. In this paper, conventional triaxial compression test and K0 consolidation unloading test were conducted with mucky soil and silty clay to obtain the deformation characteristics of soils under different stress paths. Experiment results show that the soil samples exhibit distinct stress-strain characteristics under different stress paths, but they all show nonlinearity. The initial tangent modulus increases as the consolidation confining pressure intensifies. Then, based on the test data, the power function relationship between initial tangent modulus and confining pressure under unloading was verified. Simultaneously, a hyperbola function to express stress-strain relation of soils under the K0 consolidation unloading condition was proposed and proved. Finally, the formulas of the tangent modulus under K0 consolidation unloading were established referring to the derivation of that in Duncan–Chang model. The theoretical calculation results agree well with the test results. It can expand the use of the Duncan–Chang model and improve its application to engineering practice.
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Machado, Antônio L. T., e Carlos R. Trein. "Characterization of soil parameters of two soils of Rio Grande do Sul in modeling the prediction of tractive effort". Engenharia Agrícola 33, n. 4 (agosto 2013): 709–17. http://dx.doi.org/10.1590/s0100-69162013000400010.
Testo completoAbstract (sommario):
The interaction between the soil and tillage tool can be examined using different parameters for the soil and the tool. Among the soil parameters are the shear stress, cohesion, internal friction angle of the soil and the pre-compression stress. The tool parameters are mainly the tool geometry and depth of operation. Regarding to the soils of Rio Grande do Sul there are hardly any studies and evaluations of the parameters that have importance in the use of mathematical models to predict tensile loads. The objective was to obtain parameters related to the soils of Rio Grande do Sul, which are used in soil-tool analysis, more specifically on mathematical models that allow the calculation of tractive effort for symmetric and narrow tools. Two of the main soils of Rio Grande do Sul, an Albaqualf and a Paleudult were studied. Equations that relate the cohesion, internal friction angle of the soil, adhesion, soil-tool friction angle and pre-compression stress as a function of water content in the soil were obtained, leading to important information for use of mathematical models for tractive effort calculation.
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Murray, Edward J. "An equation of state for unsaturated soils". Canadian Geotechnical Journal 39, n. 1 (1 febbraio 2002): 125–40. http://dx.doi.org/10.1139/t01-087.
Testo completoAbstract (sommario):
The enthalpy within a soil system under equilibrium conditions is investigated theoretically. Terzaghi's effective stress equation for a saturated soil is first examined and the approach extended to determine the enthalpy associated with the air, water, and solid phases, and the interactions between the phases, in an unsaturated soil. An equation of state is developed which links the stress state variables (p ua) and (ua uw) to the specific volume (v) and specific water volume (vw) and thus to the volumes of the phases. The equation is shown to provide a logical interpretation of the average volumetric "coupling" stress p'c within unsaturated soils which highlights the significance of the dual stress regime and bimodal structure. The new equation is compared with previously reported experimental data on kaolin and a lateritic gravel. The agreement is good and it provides insight into unsaturated soil strength and deformation behaviour and clarifies various previously identified anomalies.Key words: partial saturation, unsaturated soils, thermodynamics, effective stress, equation of state, critical state.
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Li, Shuang, Yun Xie, Gang Liu, Jing Wang, Honghong Lin, Yan Xin e Junrui Zhai. "Water Use Efficiency of Soybean under Water Stress in Different Eroded Soils". Water 12, n. 2 (30 gennaio 2020): 373. http://dx.doi.org/10.3390/w12020373.
Testo completoAbstract (sommario):
Soil erosion could change the effective storage of soil moisture and affected crop water use efficiency (WUE). To quantitative study differences in the WUE of soybean and the crop’s response to water stress for soils with different degrees of erosion in northeastern China, three erosion degrees—(1) lightly, (2) moderately and (3) severely—eroded black undisturbed soils and four years (from 2013 to 2016) of soybean pot experiments were used to control soil water content (100%, 80%, 60%, and 40% field capacity (FC)) and observe the crop growth processes. To study the relationships between erosion–water use–productivity, the following results were achieved: (1) the optimal water content was 80% FC for lightly eroded soil (L) and 100% FC for both moderately (M) and severely (S) eroded soil. Yield (Y) was best in M with the value of 3.12 t ha−1, which was 4.6% and 85.5% higher than L and S, respectively. Under the conditions of adequate water supply, there was no significant change in Land M, but the values were significantly different for the S ( p < 0.05). (2) Y and biomass (B) were sensitive to water stress except in the branching stage. (3) The values of WUEY and WUEB for the three eroded soils were the best at 80% FC. The stress coefficient (SF) values of the three eroded soils were not significantly different. In the flowering and pod formation stage, the SF reached the maximum under waterlogging stress. While the water shortage stress reached the maximum in the seed filling stage, the soil water content decreased by 10%, and the WUEB decreased by 15%, which was 2.5 times more powerful than the waterlogging stress. This study indicated the change in soybean growth with respect to the water response caused by soil erosion, and provided a scientific basis and data for the reasonable utilization of black soil with different erosion intensities. The results also provided important parameters for the growth of simulated crops.
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Banjac, Borislav, Miodrag Dimitrijevic, Sofija Petrovic, Velimir Mladenov, Dusana Banjac e Biljana Kiprovski. "Antioxidant variability of wheat genotypes under salinity stress in situ". Genetika 52, n. 3 (2020): 1145–60. http://dx.doi.org/10.2298/gensr2003145b.
Testo completoAbstract (sommario):
Crop cultivation under the open-field conditions depends on a variety of biotic and abiotic factors which cause plant stress and deterioration. Due to high soil salinity, some soils can be an unfavourable growing environment for most plants. As a low productivity soil type, solonetz soils are a stressful growing environment, causing plant deterioration. Plants have developed a complex antioxidative defense system as a precaution against oxidative stress caused by high soil salinity. The trial was set up on a halomorphic soil type-solonetz. The research included ten cultivars, one local population of hexaploid wheat (Triticum aestivum ssp. aestivum L.) and one cultivar of triticale (Triticosecale W.). The activity of enzymatic and non-enzymatic antioxidants in plant antioxidative defense system was detected during the trial, as well as lipid peroxidation. The analysis of biochemical markers was done in the flowering stage, and then in the milk maturity phase. Research results of the tested components revealed the highest stress tolerance exhibited by genotypes Banatka and Bankut 1205. Understanding the process of oxygen radical production by the plant tissue contributes to breeding wheat cultivars for better stress tolerance. Selection of genotypes better adapted to growing conditions in solonetz soils could facilitate a more economically justifiable wheat production, and promote utilization of the lower-quality soil types in agriculture.
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Erb, W. A., A. D. Draper e H. J. Swartz. "Relation between Moisture Stress and Mineral Soil Tolerance in Blueberries". Journal of the American Society for Horticultural Science 118, n. 1 (gennaio 1993): 130–34. http://dx.doi.org/10.21273/jashs.118.1.130.
Testo completoAbstract (sommario):
The relationship between moisture stress and mineral soil tolerance was studied by placing 10 blueberry (Vaccinium) clones in a Berryland sand soil high in organic matter (Berryland) and a Galestown sandy clay loam soil (Galestown) and subjecting them to one of two moisture regimes. The Berryland and Galestown soils represent an excellent blueberry soil and a mineral soil, respectively. A moderate degree of water stress influenced biomass partitioning in blueberries in a similar manner as stress induced by culture on mineral soil. Berryland control plants on Berryland partitioned more biomass into leaves and produced more dry matter and leaf area than plants on Galestown or those moisture stressed. Net assimilation rate and relative growth rate were not significantly different between soil or moisture treatments. The primary reason for the reduction in absolute growth rate due to soil type or moisture stress was a significantly lower leaf area duration on Galestown soil and in-moisture stressed plants. Clones differed in instantaneous transpiration, leaf conductance, and apparent photosynthesis and the ability to partition biomass into various plant parts. By selecting for increased leafiness, a high photosynthetic rate, and a more energy efficient root system, improvement in mineral soil tolerance should be possible.
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Zhao, Xiaolong, Jungao Zhu e Hanbing Bian. "Applicability of UH model to coarse-grained soil". MATEC Web of Conferences 295 (2019): 03007. http://dx.doi.org/10.1051/matecconf/201929503007.
Testo completoAbstract (sommario):
Large-scale triaxial, K0 compression and constant stress ratio path tests were carried out on two kinds of coarse-grained soils. Stress-strain relationships of these tests were simulated by using UH model for sands to study the applicability of the model to different stress paths of coarse-grained soil, and the results were compared with those of Duncan’s E-B model. It is shown that the mechanical behaviors of coarse-grained soil can be well described by the UH model, and overall its capacity to reflect stress-strain relationship under different stress paths is better than that of Duncan’s E-B model. Finally, the UH model and Duncan’s E-B model were used for stress-deformation analysis of a core rockfill dam. The applicability of UH model for sands to coarse-grained soil was verified.
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Tang, C., e N. C. Turner. "The influence of alkalinity and water stress on the stomatal conductance, photosynthetic rate and growth of Lupinus angustifolius L. and Lupinus pilosus Murr." Australian Journal of Experimental Agriculture 39, n. 4 (1999): 457. http://dx.doi.org/10.1071/ea98132.
Testo completoAbstract (sommario):
A glasshouse experiment examined the effect of water stress on the growth of Lupinus angustifolius L. and Lupinus pilosus Murr. grown on an acid sandy soil, a limed sandy soil and an alkaline clay soil. Decreasing soil water content decreased the stomatal conductance and photosynthetic rate, and reduced plant growth. The responses of both species to water stress were generally similar in the sand and limed soils, but in the alkaline soil, L. angustifolius grown with limited water had markedly lower conductances and photosynthetic rates than the plants in the other soils at equivalent soil water contents. In adequately watered plants, the lupin species differed substantially in their growth response to soil types. Whereas the growth of L. pilosus was unaffected, the shoot dry weight of L. angustifolius grown on the limed and alkaline soils for 25–44 days was reduced by 32–54 and 44–86%, respectively, compared with the growth in the acid soil. The poor growth of L. angustifolius appeared to be primarily due to its poor root growth. In the alkaline soil, water stress reduced rather than stimulated root growth. The results suggest that, in the field, the limited root growth of L. angustifolius on alkaline soils will exacerbate water deficits when the topsoil dries out in the latter part of the season.
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Абжалимов, Раис, e Rais Abzhalimov. "The pattern of distribution of vertical stress of swelling of soil under foundations and underground structures". Construction and Architecture 4, n. 3 (31 ottobre 2016): 60–67. http://dx.doi.org/10.12737/21848.
Testo completoAbstract (sommario):
Examines the pattern of distribution of vertical stress of swelling of soil under foundations and underground structures, stress-strain state (VAT) system, "swelling soil-Foundation - structure" for the strip Foundation and VAT for a square Foundation when uneven wetting of the Foundation soil. Provides recommendations for selection of type of foundations on swelling soils.
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PK, Srivastava, M. Gupta, A. Pandey, V. Pandey, N. Singh e Tewari SK. "Effects of sodicity induced changes in soil physical properties on paddy root growth". Plant, Soil and Environment 60, No. 4 (8 aprile 2014): 165–69. http://dx.doi.org/10.17221/926/2013-pse.
Testo completoAbstract (sommario):
A study was conducted to investigate the influence of sodicity induced changes in soil physical properties on paddy root growth in the normal agriculture, semi-reclaimed and sodic soils. The root growth (length, length density, biomass and distribution pattern) were unfavourably affected by the soil physical properties (bulk density, soil aggregate stability, available water content, hydraulic conductivity and soil water retention potential) in the case of sodic soil. The microbial biomass carbon, bacterial, fungal population and dehydrogenase activity showed the lower values in the case of sodosol compared to the normal soil. These soil biological properties tend to sustain paddy root growth in normal and semi-reclaimed soils. Principal component analysis revealed that soil physical properties accounted for 98.2% of total variance in root growth. The study revealed that salt stress induces changes in soil physical properties limiting paddy root growth in the salt affected soils. It is important to reclaim sodosols to alleviate salt induced physical stress for optimum paddy root growth.
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Gould, Scott J. F., Jayantha Kodikara, Pathmanathan Rajeev, Xiao-Ling Zhao e Stewart Burn. "A void ratio – water content – net stress model for environmentally stabilized expansive soils". Canadian Geotechnical Journal 48, n. 6 (giugno 2011): 867–77. http://dx.doi.org/10.1139/t10-108.
Testo completoAbstract (sommario):
A new mathematical model is presented that describes the shrinkage curve of environmentally stabilized soils. Environmentally stabilized soils are defined as those that have undergone a sufficient number of wet–dry cycles to reach a stable soil structure. The model is applicable for fitting to soils that exhibit all typical zones of soil shrinkage behaviour and to those soils that do not exhibit structural and (or) residual shrinkage behaviour. The fitting parameters in this model are directly related to features of the shrinkage curve and have direct relevance to soil mechanics theory and practice. The model is applied to data from 20 different datasets reported in literature with excellent fitting achieved. This model is extended to incorporate the effect of net stress, creating a surface describing soil volumetric behaviour in response to changes in water content and net stress.
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Shaw, E. Ashley, e Diana H. Wall. "Biotic Interactions in Experimental Antarctic Soil Microcosms Vary with Abiotic Stress". Soil Systems 3, n. 3 (27 agosto 2019): 57. http://dx.doi.org/10.3390/soilsystems3030057.
Testo completoAbstract (sommario):
Biotic interactions structure ecological communities but abiotic factors affect the strength of these relationships. These interactions are difficult to study in soils due to their vast biodiversity and the many environmental factors that affect soil species. The McMurdo Dry Valleys (MDV), Antarctica, are relatively simple soil ecosystems compared to temperate soils, making them an excellent study system for the trophic relationships of soil. Soil microbes and relatively few species of nematodes, rotifers, tardigrades, springtails, and mites are patchily distributed across the cold, dry landscape, which lacks vascular plants and terrestrial vertebrates. However, glacier and permafrost melt are expected to cause shifts in soil moisture and solutes across this ecosystem. To test how increased moisture and salinity affect soil invertebrates and their biotic interactions, we established a laboratory microcosm experiment (4 community × 2 moisture × 2 salinity treatments). Community treatments were: (1) Bacteria only (control), (2) Scottnema (S. lindsayae + bacteria), (3) Eudorylaimus (E. antarcticus + bacteria), and (4) Mixed (S. lindsayae + E. antarcticus + bacteria). Salinity and moisture treatments were control and high. High moisture reduced S. lindsayae adults, while high salinity reduced the total S. lindsayae population. We found that S. lindsayae exerted top-down control over soil bacteria populations, but this effect was dependent on salinity treatment. In the high salinity treatment, bacteria were released from top-down pressure as S. lindsayae declined. Ours was the first study to empirically demonstrate, although in lab microcosm conditions, top-down control in the MDV soil food web.
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Junaideen, Sainulabdeen Mohamed, Leslie George Tham e Chack Fan Lee. "Instability of Compacted Residual Soil". Geosciences 11, n. 10 (24 settembre 2021): 403. http://dx.doi.org/10.3390/geosciences11100403.
Testo completoAbstract (sommario):
Static liquefaction of loose sands has been observed to initiate at stress ratios far less than the steady-state stress ratio. Different collapse surface concepts largely based on undrained triaxial test results have been proposed in the literature to explain the above instability phenomenon of loose sands. Studies of the instability behavior of fill material derived from residual soils remain limited. The present study investigated the instability behavior of a compacted residual soil using the conventional undrained triaxial tests and specially equipped constant shear triaxial tests. The test results were characterized in the p’: q: v space using the current state parameter with respect to the steady-state line for the residual soil. A modified collapse surface that has gradients varying with p’ and v was proposed for the loose residual soil to represent the instability states of undrained loading. Under constant shear stress conditions, the soil can mobilize stress ratios higher than those defined by the modified collapse surface. An instability surface was therefore presented for the instability states reached in static loading. Further, an alternative method of deducing the instability surface from the undrained stress paths was introduced.
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Zhou, Qi, Shuang Song, Xin Wang, Chao Yan, Chunmei Ma e Shoukun Dong. "Effects of drought stress on flowering soybean physiology under different soil conditions". Plant, Soil and Environment 68, No. 10 (17 ottobre 2022): 487–98. http://dx.doi.org/10.17221/237/2022-pse.
Testo completoAbstract (sommario):
Soybean is highly sensitive to drought stress during its flowering period. Heinong84 (HN84) and Hefeng46 (HF46) were planted in clay loam, silty loam, and sandy clay. We studied the effects of drought stress on the content of membrane lipid peroxides in flowering soybean leaves, the activity of antioxidant enzymes, and the activity of key enzymes of nitrogen metabolism under different soil conditions. Our results showed that soybean had clear physiological responses to drought stress. With increasing drought stress, the malondialdehyde, glutathione reductase, and glutathione peroxidase levels in soybean leaves increased continuously. Superoxide dismutase, peroxidase, glutamine synthase, and glutamate synthase levels increased with drought stress, reaching a maximum under moderate drought stress and then decreased; nitrate reductase activity decreased continuously. Under the condition of sufficient water, the performance of soybean in the three soils is almost the same, but there are differences under drought stress; particularly, soybean grown in clay loam shows the strongest drought resistance. In summary, the physiological state of soybean is easily affected by drought stress, which varies greatly among different cultivars and in different soil types.
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Lo, Irene M. C., Jianhong Zhang, Liming Hu e Shanzhi Shu. "Effect of Soil Stress on Cadmium Transport in Saturated Soils". Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management 7, n. 3 (luglio 2003): 170–76. http://dx.doi.org/10.1061/(asce)1090-025x(2003)7:3(170).
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Morsy, Amr M., e Jorge G. Zornberg. "Soil-reinforcement interaction: Stress regime evolution in geosynthetic-reinforced soils". Geotextiles and Geomembranes 49, n. 1 (febbraio 2021): 323–42. http://dx.doi.org/10.1016/j.geotexmem.2020.08.007.
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Rabinovich, Mikhail. "Calculation of thermal stress-strain state of soil base under the building on permafrost soil". E3S Web of Conferences 97 (2019): 04056. http://dx.doi.org/10.1051/e3sconf/20199704056.
Testo completoAbstract (sommario):
Article presents problem statement and solution for joint calculation of temperature regime and stress-strain state of permafrost soils under building footing, with consideration of thermal impact from on-surface and buried high-temperature utilities. Based on a series of optimization tasks, a design model for stress-strain state has been developed, solutions of test problems have been obtained and analyzed to determine the degree of influence of temperature stresses and relation of the deformation characteristics of frozen soil in the negative temperature spectrum on the stress distribution and settlement values of frozen soil base under the building.
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Alias, Asmidar, Mohd Jamaludin Md Noor e Abdul Samad Abdul Rahman. "Prediction of Stress-Strain Response Using Rotational Multiple Yield Surface Framework in Malaysian Residual Soil". Key Engineering Materials 843 (maggio 2020): 132–37. http://dx.doi.org/10.4028/www.scientific.net/kem.843.132.
Testo completoAbstract (sommario):
Soil settlement is normally quantified using conventional soil volume change models which are solely based on the effective stress and the role of shear strength is ignored due to the difficulties to incorporate in the framework. The Rotational Multiple Yield Surface Framework (RMYSF) is a soil volume change model developed from the standpoint of the interaction between the effective stress and shear strength. RMYSF incorporates the development of mobilised shear strength within the body of the soil whenever the soil is subjected to anisotropic compression. Currently the framework has been applied to predict the soil anisotropic stress-strain behaviour at any effective stress. This paper present the enhancement of this volume change framework using normalisation of axial strain with the understanding that the failure axial strain is not unique, but increases as the effective stress increases. This technique has essentially produced a better accuracy in the prediction of the stress-strain response for Malaysian residual soils. A series of drained tri-axial tests under various effective stresses has been conducted using specimens of 50mm diameter and 100mm height and from the stress-strain curves the inherent mobilised shear strength envelopes at various axial strains have been determined. These mobilised shear strength envelopes were then applied for the prediction of the soil stress-strain response. An excellent agreement between the predicted and the actual stress-strain curves has been achieved.
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Sheng, Daichao, Delwyn G. Fredlund e Antonio Gens. "A new modelling approach for unsaturated soils using independent stress variables". Canadian Geotechnical Journal 45, n. 4 (aprile 2008): 511–34. http://dx.doi.org/10.1139/t07-112.
Testo completoAbstract (sommario):
Although a number of constitutive models for unsaturated soils exist in the literature, some fundamental questions have not been fully answered. There are questions related to (i) the change of the yield stress with soil suction, (ii) modelling slurry soils, and (iii) the smooth transition between saturated and unsaturated soil states. This paper addresses these questions by proposing an alternative modelling approach. The paper first presents a volumetric model for unsaturated soils. This volumetric model is then used to derive the yield surface in the suction – mean stress space. Hysteresis associated with soil-water characteristic curves is then formulated in the same framework of elastoplasticity. It is shown that volume collapse during wetting and plastic shrinkage during initial drying are both direct results of a suction-dependent hardening law. The proposed model seems to be more flexible in modelling different types of unsaturated soils than most models in the literature. The model can be applied to soils that are dried or loaded from initially slurry conditions, for soils that have low to high air-entry values, and for compacted soils as well.
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Hou, Yaling, Wenzhi Zeng, Menglu Hou, Zhao Wang, Ying Luo, Guoqing Lei, Bo Zhou e Jiesheng Huang. "Responses of the Soil Microbial Community to Salinity Stress in Maize Fields". Biology 10, n. 11 (29 ottobre 2021): 1114. http://dx.doi.org/10.3390/biology10111114.
Testo completoAbstract (sommario):
To investigate the diversity and structure of soil bacterial and fungal communities in saline soils, soil samples with three increasing salinity levels (S1, S2 and S3) were collected from a maize field in Yanqi, Xinjiang Province, China. The results showed that the K+, Na+, Ca2+ and Mg2+ values in the bulk soil were higher than those in the rhizosphere soil, with significant differences in S2 and S3 (p < 0.05). The enzyme activities of alkaline phosphatase (ALP), invertase, urease and catalase (CAT) were lower in the bulk soil than those in the rhizosphere. Principal coordinate analysis (PCoA) demonstrated that the soil microbial community structure exhibited significant differences between different salinized soils (p < 0.001). Data implied that the fungi were more susceptible to salinity stress than the bacteria based on the Shannon and Chao1 indexes. Mantel tests identified Ca2+, available phosphorus (AP), saturated electrical conductivity (ECe) and available kalium (AK) as the dominant environmental factors correlated with bacterial community structures (p < 0.001); and AP, urease, Ca2+ and ECe as the dominant factors correlated with fungal community structures (p < 0.001). The relative abundances of Firmicutes and Bacteroidetes showed positive correlations with the salinity gradient. Our findings regarding the bacteria having positive correlations with the level of salinization might be a useful biological indicator of microorganisms in saline soils.
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Saye, Steven R., Bryan P. Kumm e Alan J. Lutenegger. "Estimating overconsolidation ratio (OCR) in structured and unstructured cohesive soil with field vane tests referencing soil index properties". Canadian Geotechnical Journal 58, n. 1 (gennaio 2021): 125–41. http://dx.doi.org/10.1139/cgj-2019-0414.
Testo completoAbstract (sommario):
Estimation of the preconsolidation stress and overconsolidation ratio (OCR) in uniform cohesive soils using a field vane is variably impacted by the combined effects of soil type and plasticity, geologic history, structured vs. unstructured behavior, and the presence of sand or organic matter. Published empirical correlations for cohesive soils consider the effects of soil type and plasticity, but significant variability can occur with changes in soil structure and organic matter content for specific instances. The adaption of the “stress history and normalized soil engineering properties” (SHANSEP) format improves the characterization of overconsolidated soils using field vane tests by applying a proposed empirical approach to identify structured soils from unstructured soils and updating the SHANSEP-based approach to separately evaluate structured and unstructured soils. Validation of the correlation coefficients for individual projects will be needed as the approach is applied to new geologic materials and with potentially different field vane equipment and laboratory testing procedures used to characterize the soils. This additional testing provides an opportunity to improve the correlations for specific conditions and reduce the variability in the OCR assessments.
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Chegenizadeh, Amin, e Hamid Nikraz. "Shear Test on Reinforced Clay". Advanced Materials Research 250-253 (maggio 2011): 3223–27. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.3223.
Testo completoAbstract (sommario):
Composite soils have been widely used in civil engineering applications, especially in slopes, embankment dam and landfills. This paper aims to investigate effect of fiber inclusion on shear stress of composite soil (i.e. clay composite). A series of laboratory direct shear tests carried out to evaluate fiber effect on strength behavior of composite clay. Clay was selected as soil part of the composite and plastic fiber was used as reinforcement. The fiber parameters differed from one test to another, as fiber length were changed from 20 mm to 65 mm and fiber content were varied from 0.7% and 2%.Normal stress kept constant at 150 kpa. For each test, stress_ displacement graph derived and the results were compared. The results proved that inclusion of fiber affected shear stress behaviour of clay composite so that increasing in fiber content and length caused increasing in shear stress.
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Wilson, Christopher George, Keith E. Schilling e Thanos Papanicolaou. "Evaluating Causal Factors That Influence the Spatial and Temporal Variability of Streambank Erosion in Iowa". Journal of the ASABE 65, n. 6 (2022): 1465–73. http://dx.doi.org/10.13031/ja.14894.
Testo completoAbstract (sommario):
Highlights Critical shear stress and erodibility were quantified for Iowa streambanks at regional and seasonal scales. Variations in critical shear stress and erodibility were apparent across landform areas. Values of critical shear stress in northern Iowa were less than those in southern Iowa. Seasonal variations in critical shear stress and erodibility are due to soil moisture and freeze-thaw cycles. Abstract. Streambank erosion exhibits high variability both spatially and temporally, and few studies have attempted to characterize the causal factors of the variability at regional and seasonal scales. This study combines geotechnical field measurements with historical trends of soil moisture and temperature to quantify the spatial and temporal variability of critical shear stress and erodibility in streambanks of the Major Land Resource Areas of Iowa (MLRAs). The data suggest that till-derived soils in north-central and northeast Iowa lack cohesion compared to loess-derived soils in southern Iowa. Thus, critical shear stress values from the northern parts of the state were significantly less than those from western and southern Iowa. A multivariate regression equation was developed using properties of texture and bulk density to quantify critical shear stress values for all stream bank soil series in the state. The cumulative distribution functions of these values visually reflect the separation between the critical shear stress values of the different MLRAs, with the loess-derived soils in western and southern Iowa having similar, overlapping patterns, in contrast to MLRAs in north central and northeast Iowa with the till-derived soils. Temporally, the critical shear stress reaches minimum values during March when soil moisture is high and there are several freeze-thaw events. This is most apparent with bank soils in eastern Iowa. Keywords: Cohesion, Critical shear stress, Erodibility, Sediment, Streambank erosion.
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Carducci, Carla Eloize, Geraldo César de Oliveira, Walmes Marques Zeviani, Henrique Aparecido Laureano, Samara Martins Barbosa, Eduardo da Costa Severiano e Nilton Curi. "Preconsolidation stress of gibbsitic and kaolinitic Oxisols under a multipractice conservationist coffee system". Semina: Ciências Agrárias 42, n. 3 (19 marzo 2021): 1049–68. http://dx.doi.org/10.5433/1679-0359.2021v42n3p1049.
Testo completoAbstract (sommario):
Our goal was to analyze the impact of a multipractice soil conservationist system on coffee production in tropical soils (LATOSSOLO VERMELHO-AMARELO caulinítico/kaolinitic Haplustox and LATOSSOLO VERMELHO-gibbsítico/gibbsitic Acrustox) in Minas Gerais, Brazil. In the experimental area, the soil management involved a set of multiple conservationist practices during cultivation for more than 3.5 yrs. Soil samples were collected at 0-5, 10-15, and 20-25 cm depths at two positions: planting rows and between rows. The soil physical and mechanical properties were determined, with a focus mainly on the preconsolidation stress model (preconsolidation stress versus matric tension). For the purpose of analysis, a split-split plot experimental design was implemented. A linear mixed regression model (LMR) was fitted, and Wald’s test was performed (P < 0.05). An improvement of soil physical quality for both Oxisols was observed at the planting row position. The effects of multipractice soil management after 3.5 yrs of cultivation in association with increased gibbsite content could promote new soil structure organization, as revealed by LMR, resulting in more resilient soils (between rows) and increasing the resistance to external pressures on gibbsitic Acrustox. Overall, the findings herein are in concordance with global trends towards conservationist practices that may alleviate soil compaction in agricultural systems to maintain environmental sustainability.
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Mustikarini, Eries D., G. Ibnu Prayoga, R. Santi, Siti Khodijah e T. Lestari. "Tolerance of F6 Red Rice Lines against Iron (Fe) Stress". Jurnal Lahan Suboptimal : Journal of Suboptimal Lands 10, n. 1 (5 aprile 2021): 64–77. http://dx.doi.org/10.36706/jlso.10.1.2021.511.
Testo completoAbstract (sommario):
Dryland area in Indonesia reaches 108.8 millions ha (69.4%) of the total dry land with the potential to expand the area of food crops reaching 7.1 million ha, which is dominated by ultisol and oxisol soil types. Plant constraint cultivation on ultisol soil types is the acidic soil pH with high Al and Fe levels. One of the efforts that can be made to cultivate plants on ultisol soil is the selection of plants that are tolerant of Fe stress. This study aimed to determine a tolerance level and F6 red rice lines that were tolerant of iron (Fe) stress in ultisol soils. The experimental design used was factorial Completely Randomized Design (CRD) consisting of 2 factors, the first factor consisted of 12 treatments (10 test lines and 2 comparison varieties) and the second factor was iron stress with concentrations (0 ppm and 551,55 ppm). The stress was applied after 3 WAP. The stress resistance test to iron (Fe) should that all lines of red rice F6 on ultisol soils have a score of 1 which indicates the stress tolerance of Fe at a concentration of 551,55 ppm Fe. The 23A-56-30-25-12 and 23A-56-30-25-13 lines were the best lines that were tolerant of 551,55 ppm iron (Fe) stress with the highest growth and yield. The lines tested can be developed on ultisol soils because they are tolerant of Fe.
45
Harris, H. D., e D. M. Bakker. "A soil stress transducer for measuring in situ soil stresses". Soil and Tillage Research 29, n. 1 (febbraio 1994): 35–48. http://dx.doi.org/10.1016/0167-1987(94)90100-7.
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Theocaris, P. S., G. A. Papadopoulos e B. Badalouka. "Soil structure interactions to stress pulses traveling through the soil". Soil Dynamics and Earthquake Engineering 10, n. 7 (ottobre 1991): 348–56. http://dx.doi.org/10.1016/0267-7261(91)90024-t.
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Tremblay, Hélène, Serge Leroueil e Jacques Locat. "Mechanical improvement and vertical yield stress prediction of clayey soils from eastern Canada treated with lime or cement". Canadian Geotechnical Journal 38, n. 3 (1 giugno 2001): 567–79. http://dx.doi.org/10.1139/t00-119.
Testo completoAbstract (sommario):
The method of soil stabilization is well known and has been used throughout the world for many decades to improve some soil properties. Although many researchers have studied the effect of adding a cementing agent to a soil, not many of these researchers have explored the effect of treatment on the resulting properties of high water content soils like dredged material. Also, there has been little work concerning the prediction of the mechanical changes to the soil. Therefore, this paper summarizes the results of a research project conducted to define the general mechanical behavior of high water content clayey soils from eastern Canada treated with lime or cement, in terms of compressibility. In the light of this research, the general compressibility behavior has been obtained, defined by relationships between initial void ratio, additive content, and vertical yield stress for a given inorganic or organic soil. These relationships have been normalized on the basis of the one-dimensional compression curve of the remolded and reconstituted untreated soil to give a simple method for predicting the vertical yield stress of a treated soil for any initial void ratio and its resistance to compression.Key words: stabilization, compressibility, yield stress, clayey soils, lime, cement.
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Sivapullaiah, P. V., A. Sridharan e H. N. Ramesh. "Strength behaviour of lime-treated soils in the presence of sulphate". Canadian Geotechnical Journal 37, n. 6 (1 dicembre 2000): 1358–67. http://dx.doi.org/10.1139/t00-052.
Testo completoAbstract (sommario):
Lime has been used extensively to improve the shear strength of fine-grained soils. It has been recently reported that the presence of sulphate causes abnormal volume changes in lime-stabilized soil. The paper presents the strength behaviour of lime-treated montmorillonitic natural black cotton soil in the presence of varying sulphate contents after curing for periods of up to 365 days. Alteration of soillime reactions in the presence of sulphate affects the strength development by cementation. Consequently, the stressstrain behaviour effective stress paths of soil cured with sulphate are similar to those of normally consolidated soil rather than cemented soils. The reduction in shear strength due to a reduction in effective cohesion intercept occurs for lime-treated soil cured with sulphate for long periods.Key words: clays, cohesion, fabric, friction, shear strength.
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Wei, Hongjian, Yongqi Wang, Juming Zhang, Liangfa Ge e Tianzeng Liu. "Changes in Soil Bacterial Community Structure in Bermudagrass Turf under Short-Term Traffic Stress". Agriculture 12, n. 5 (6 maggio 2022): 668. http://dx.doi.org/10.3390/agriculture12050668.
Testo completoAbstract (sommario):
Bermudagrass (Cynodon dactylon (L.) Pers.) is an extensively utilized turf grass for football fields and golf courses. Traffic stress is one of the most important stresses affecting the life of turf, which leads to a decrease in turf quality and changes in the soil microbial community structure. The structural change in soil bacterial community is an important reference for turf growth, maintenance, and restoration. Tifgreen bermudagrass turf and Common bermudagrass turf were applied with traffic treatment by a traffic simulator with moderate intensity to explore soil bacterial community structural changes in turf under traffic stress. The environmental factors including turf quality indicators and soil properties were measured, and the association of the soil bacterial community diversity with the environment factors was analyzed. As a result, traffic treatments significantly changed the soil properties and bacterial community composition in two bermudagrass species at the phylum and genus level. Actinobacteria, Chloroflexi, and Verrucomicrobia showed significantly high abundance in turf soils under traffic stress. The soil bacterial ACE, Chaol, and Shannon indexes of two bermudagrass species under traffic stress were significantly lower than non-traffic stress. The bacterial community structure was highly correlated with some turf quality indicators and soil properties under traffic stress. Our results illustrate that compared to Common bermudagrass, Tifgreen bermudagrass had better turf quality under traffic stress and less changes in its bacterial community structure, perhaps Tifgreen bermudagrass is a better choice of grass for sports turf as opposed to Common bermudagrass.
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HONDA, Michinori, Atsushi IIZUKA, Katsuyuki KAWAI e Daizo KARUBE. "Stress-Strain Relationship for Unsaturated Soil." Doboku Gakkai Ronbunshu, n. 659 (2000): 153–64. http://dx.doi.org/10.2208/jscej.2000.659_153.
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