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1
Hamad, Asal Mahmud, e Mahmood Gazey Jassam. "A Comparative Study for the Effect of Some Petroleum Products on the Engineering Properties of Gypseous Soils". Tikrit Journal of Engineering Sciences 29, n. 3 (15 ottobre 2022): 69. http://dx.doi.org/10.25130/tjes.29.3.7.
Testo completoAbstract (sommario):
Gypseous soils are considered problematic soils because the soil cavities happen during receiving the water or this type of soil and solving gypsum materials and contract in a soil volume. In this study, three types of gypseous soils are used; soil1, soil2, and soil3 with gypsum content (28.71%, 43.6%, and 54.88%) respectively, petroleum products (engine oil, fuel oil, and kerosene) are added to the soils with percentages (3%, 6%, 9%, and 12%) for each product. The result showed that specific gravity, liquid limit, optimum moisture content (O.M.C), and maximum dry density decreased with an increased percentage of product for all types of products. The direct shear (dry and soaked case) results show that increasing the (angle of internal friction and the soil cohesion) for soil1, soil2, and soil3 by adding engine oil and fuel oil. Still, when the soils were treated with kerosene, the angle of internal friction increased while cohesion decreased. The collapse potential for the treated soils increases with increasing gypsum content for all petroleum products. The collapse potential (CP) for (soil1) decreased by 47% when using 6% of the engine oil, 48.8% when using 9% of the fuel oil, and 55% when using 9% of the kerosene. The same percentage of the petroleum products (engine oil, fuel oil, and kerosene) decrease the collapse potential for (soil2), (47%, 46%, and 50%) respectively and decrease the collapse potential for (soil 3), (51%, 47.7%, and 52%) respectively. In the unconfined compressive test applied on (soil1) using maximum density, the results show that the soil strength increased (26% and 10%) when using 6% and engine oil and fuel oil, respectively, while the soil strength decreased by 29% when treated with 9% of kerosene.
2
Mohamed, Ahmed, Saad Saadi, Ibrahim Gart e Fahmy Mohammed. "Assessing the Improvement of Geotechnical Properties of Clayey Soil Using a Substrate Cement Mortar Material, from Ilgin, Konya City, Turkey". Iraqi Geological Journal 57, n. 2A (31 luglio 2024): 162–76. http://dx.doi.org/10.46717/igj.57.2a.12ms-2024-7-22.
Testo completoAbstract (sommario):
The increase in needs and the decrease in places with good, usable foundation soil have made the construction of engineering structures on problematic soils mandatory. Problematic soils generally do not have sufficient bearing capacity and soil strength, which may create an environment prone to high settlement or liquefaction. To investigate potential ways to enhance the compaction, undesirable or problematic plasticity, and soil’s strength characteristics, various geotechnical tests have been carried out on clayey soils and their mixtures treated with a Substrate Cement Mortar (0, 4, 8, and 12% by weight). These tests involved Atterberg limits, dry density, compaction, and shear strength. The obtained results show that the addition of substrate cement materials increased the dry density of soil treated with SCM, which can significantly enhance the soil properties. Meanwhile, adding SCM decreased the soil's plasticity limits. Furthermore, adding 12% Substrate Cement Mortar resulted in the lowest optimum moisture content and the maximum dry unit weight. Soil treated with 12% also exhibits maximum cohesion and shear strength. This research led to the conclusion that the utilization of Substrate Cement Mortar additive is an inexpensive product and has significantly improved the soil’s geotechnical parameters.
3
Pahlevi Munirwan, Reza, e Munirwansyah Munirwansyah. "Assessing slope failure of soil erodibility problem by soil dispersive identification". E3S Web of Conferences 340 (2022): 01006. http://dx.doi.org/10.1051/e3sconf/202234001006.
Testo completoAbstract (sommario):
Dispersive soils are becoming a common building material. Due to their susceptibility to internal erosion and leakage, dispersive soils should only be used in combination with precise engineering measures to avoid catastrophic failures. Dispersive soils stabilization is critical and has been investigated in several studies conducted throughout the world. Erosion is a significant issue in structures built on sloping contours. As was the case with St. 670+250 Lipat Kajang road in Aceh Singkil. Soil erosion happens as a result of water’s dispersion and transport force. Dispersive soil is one of the factors that contribute to an increase in the soil erodibility index. The objective of this research is to develop a method for enhancing the soil’s dispersive qualities. In this investigation, specimens were prepared in three different soil mix plans (10%, 20%, and 30%) and then tested using a pinhole. The quantity of erodibility that happens in Sta. 670 + 250 Lipat Kajang - Aceh Singkil Regency is based on the results of testing the soil's dispersive properties because the soil in this area is highly dispersive.
4
Najafi-Ghiri, M., e A. Abtahi. "Potassium fixation in soil size fractions of arid soils". Soil and Water Research 8, No. 2 (15 maggio 2013): 49–55. http://dx.doi.org/10.17221/52/2012-swr.
Testo completoAbstract (sommario):
Amounts of potassium (K) fixed in soil fractions of 10 calcareous soils of southern Iran were measured to evaluate the contributions of different soil size fractions to K fixation. Soil particles were fractionated after dispersion of the soils with an ultrasonic probe. Potassium fixation analysis was done by addition of 1000 mg K/kg samples. Mineralogy of the size fractions was determined by X-ray diffraction. The clay fractions were dominated by smectite, chlorite, mica, and palygorskite. Potassium fixation capacities ranged from 104 to 148 mg/kg for clay, from 102 to 155 mg/kg for silt, and from 96 to 187 mg/kg for sand fractions. A positive and significant relationship (P < 0.05) was obtained between K fixation capacity and smectite content for the clay fractions. High amounts of K fixed in the sand fraction may be explained by a larger diffusion path of fixed K out of the frayed edges of micaceous and smectitic minerals into the extracting solution, low cation exchange capacity (CEC) of the coarse fraction and thereby the high concentration gradient along solution and interlayers, physical entrapment of K ions in coarse aggregates cemented by carbonates, and by the presence of clay particles in coarse fractions due to incomplete dispersion of coarse aggregates.
5
Cui, Jifei, Yanhao Jin, Yingjie Jing e Yu Lu. "Elastoplastic Solution of Cylindrical Cavity Expansion in Unsaturated Offshore Island Soil Considering Anisotropy". Journal of Marine Science and Engineering 12, n. 2 (9 febbraio 2024): 308. http://dx.doi.org/10.3390/jmse12020308.
Testo completoAbstract (sommario):
An elastoplastic analysis scheme for the cylindrical cavity expansion in offshore islands unsaturated soils considering anisotropy is established. The hydraulic properties and anisotropy caused by stress of unsaturated soils are coupled in an elastoplastic constitutive matrix for unsaturated soil to obtain the governing equations for the cylindrical cavity expansion problem, with an analytical solution that utilizes the original hydro-mechanical state of the soil as the initial conditions. Through a comparative analysis with other analytical solutions, the effectiveness of the new solution is verified. Moreover, the swelling response of the cylindrical cavity expansion in unsaturated soils is examined by systematically analyzing different parameters of the surrounding soil. The findings reveal that the development and rate of anisotropy in normal consolidated soil and over-consolidated soil exert a significant impact on the soil’s mechanical characteristics. Nevertheless, the alteration in the model constant h has little effect on the soil’s mechanical characteristics. The analytical solution introduces anisotropy and broadens the expansion theory of unsaturated soils to yield a more comprehensive theoretical framework for the comprehensive analysis of offshore islands’ unsaturated soils.
6
Ngole-Jeme, Veronica M. "Fire-Induced Changes in Soil and Implications on Soil Sorption Capacity and Remediation Methods". Applied Sciences 9, n. 17 (21 agosto 2019): 3447. http://dx.doi.org/10.3390/app9173447.
Testo completoAbstract (sommario):
Vegetation changes caused by fire events are visible instantly but changes in soils are less apparent, and could be short-term, long-term or permanent in nature. Research has shown that soils undergo changes in their mineralogical, geochemical, physico-chemical and biological properties after a fire event that may vary depending on the intensity and duration of the fire, and the properties of the soil. Some of these properties make significant contributions towards soil’s ability to sorb contaminants. Changes in these properties could affect soil sorption complex and the effectiveness of remediation methods used to clean these soils when contaminated. This review synthesizes available information on fire-induced changes in soil properties affecting soil sorption and the factors which dictate these changes. The implications of changes in these properties on the soil’s natural attenuation capacity and choice of remediation method to clean up fire-affected contaminated soils are also discussed.
7
Sturman, V. I., e A. N. Loginovskaya. "BACKGROUND CONCENTRATION OF HEAVY METALS (LEAD, CADMIUM, ZINC, COPPER, NICKEL, ARSENIC, MERCURY) IN SURFACE SOILS OF UDMURTIA CONTROLLED AT ENGINEERING-ECOLOGICAL RESEARCHES". Bulletin of Udmurt University. Series Biology. Earth Sciences 30, n. 3 (29 ottobre 2020): 285–94. http://dx.doi.org/10.35634/2412-9518-2020-30-3-285-294.
Testo completoAbstract (sommario):
Materials of engineering-ecological researches on various economic objects in Udmurtia are processed and systematized. Average (background) concentration of the heavy metals which are subject to obligatory control at engineering-ecological researches (lead, cadmium, zinc, copper, nickel, arsenic, mercury) for the main associations of soils and most wide-distributed kinds of soils are defined. It is revealed that with decreasing the soil’s podzol content and increasing the soil’s clay content, concentrations of heavy metals naturally raise. In general, similar soils are characterized by similar concentrations of heavy metals and similar ratios of concentration. It is established that excesses of hygienic standards on such elements as nickel, arsenic and to a lesser extent zinc, copper and cadmium, are not only something exclusive in Udmurtia, but also spreading more and more widely, especially in soils of light structure. The received average concentration can be accepted as background one at the subsequent engineering-ecological researches in the region.
8
Islam, ABMS, ZH Khan e AR Mazumder. "Pedogenesis And Characterization Of Some Soils From The Chalan Beel Of Bangladesh". Journal of the Asiatic Society of Bangladesh, Science 40, n. 2 (30 dicembre 2014): 271–81. http://dx.doi.org/10.3329/jasbs.v40i2.46025.
Testo completoAbstract (sommario):
Twenty two soil samples from four pedons representing some established soil series namely Jaonia, Haiti, Taras and Digli from the Chalan beel area of Bangladesh were studied in the field as well as in the laboratory for their pedogenesis and characterization. All the soils are heavy textured with clay contents ranging from 47 to 60 percent. The soils are moderately acidic to neutral in reaction with high base saturation. The soils have developed redoximorphic features including redox concentration and redox depletion due to periodic flooding more than 4 months in the monsoon season. Development of cambic horizon in these soils is the most notable morphogenetic feature. Gleization and weak hydromorphism are the dominant pedogenic processes. At the subgroup level the soiis were classified as Typic Endoaquepts and Aerie Endoaquepts. Finally the soiis are characterized at the family level of soil taxonomy.
Asiat. Soc. Bangladesh, Sci. 40(2): 271-281, December 2014
9
Meier, E. A., P. J. Thorburn e M. E. Probert. "Occurrence and simulation of nitrification in two contrasting sugarcane soils from the Australian wet tropics". Soil Research 44, n. 1 (2006): 1. http://dx.doi.org/10.1071/sr05004.
Testo completoAbstract (sommario):
The concentration of ammonium-nitrogen (NH4+-N) frequently exceeds that of nitrate-N (NO3−-N) in Australian wet tropical sugarcane soils. The amount of mineral N in soil is the net result of complex processes in the field, so the objective of this experiment was to investigate nitrification and ammonification in these soils under laboratory conditions. Aerobic and saturated incubations were performed for 1 week on 2 wet tropical soils. Net NO3−-N increased significantly in both soils during both types of incubation. A second series of aerobic incubations of these soils treated with NH4+-N and inoculated with subtropical nitrifying soils was conducted for 48 days. Nitrification in the wet tropical soils was not significantly affected by inoculation, and virtually all added N was nitrified during the incubation period. Mineral N behaviour of the 48-day incubations was captured with the APSIM-SoilN model. As nitrification proceeded under laboratory conditions and was able to be captured by the model, it was concluded that nitrification processes in the wet tropical soils studied were not different from those in the subtropical soils. Processes that remove NO3− from the soil, such as leaching and denitrification, may therefore be important factors affecting the proportions of NH4+-N and NO3−-N measured under field conditions.
10
Lai, Yongbiao, Songsong Bai, Jian Hou, Zongqing Zhou, Qiangling Wu, Xiaobo Lv, Liming Yang, Weixun Cao e Zhengtao Ren. "A Synthetic Chart for Internal Stability Assessment of Soils Based on Soil PSD Curves". Processes 10, n. 5 (20 aprile 2022): 807. http://dx.doi.org/10.3390/pr10050807.
Testo completoAbstract (sommario):
Awareness of granulated soils’ internal instability is an important parameter when designing granulated filters, and the ability of a granulated soil’s internal stability can be verified using the soil PSD (Particle Size Distribution) curves’ secant slopes. The current work presents a new method to calculate the soil PSD curves’ secant slopes automatically, and a synthetic diagram is presented for the potential examination of the granulated soils’ internal stability. To verify the feasibility and accuracy of this synthetic diagram, 80 specimens of soil were investigated in this work and categorized into two groups: 50 sand–gravel soils and 30 (clay)–silt–sand–gravel soils. The obtained conclusions indicate that the internal stability and instability potentials of sand–gravel soils can be distinguished successfully with a synthetic chart and the Kenney and Lau criterion but cannot be assessed with the Kezdi and Sherard criteria. None of the criteria studied here can be used for the internal stability assessment of silt–sand–gravel and clay–silt–sand–gravel soils.
11
Yu, Yiting, Huimin Peng e Jiangu Qian. "Numerical modeling bearing capacity in wetting unsaturated expansive soils". IOP Conference Series: Earth and Environmental Science 1330, n. 1 (1 maggio 2024): 012055. http://dx.doi.org/10.1088/1755-1315/1330/1/012055.
Testo completoAbstract (sommario):
Abstract To address the load-bearing deterioration of expansive soils uplift pile foundation after moisture absorption, a coupled seepage-soil deformation model for unsaturated expansive soils is implemented into ABAQUS. This modeling work consists primarily of two aspects: (1) The total strain of expansive soils has been decoupled into two parts, i.e., one caused by external loads and calculated by using Mohr-Coulomb plasticity model, and the other induced by wetting swelling and modeled by defining the moisture-swelling relation curve of expansive soils; (2) User-defined field subroutine (USDFLD) is developed by defining suction-dependent soil’s parameters (elastic modulus, cohesion and internal friction angle), and employed to simulate softening behaviors of expansive soils after moisture absorption. he above model is subsequently used to perform 3D finite element modeling and hydraulic-stress coupling analysis on the bearing capacity of pile in expansive soils before and after rainfall. Eventually, the proposed numerical method is validated by simulating a group of full-scale tests.
12
Brodský, L., A. Klement, V. Penížek, R. Kodešová e L. Borůvka. "Building soil spectral library of the Czech soils for quantitative digital soil mapping". Soil and Water Research 6, No. 4 (28 novembre 2011): 165–72. http://dx.doi.org/10.17221/24/2011-swr.
Testo completoAbstract (sommario):
Spectral libraries are the data archives of spectral signatures measured on natural and/or man-made materials. Here, the objective is to build a soil spectral library of the Czech soils (SSL-CZ). Further on, the overall aim is to apply diffuse reflectance spectroscopy as a tool for digital soil mapping. An inevitable part of the library is a metadata database that stores the corresponding auxiliary information on the soils: type of material (soil, parent material), sample preparation, location of the sample with geographic coordinates, soil classification, morphological features, soil laboratory measurements – chemical, physical, and potential biological properties, geophysical features of and climatological information on the sample location. The metadata database consists of seven general tables (General, Spatial, Soil class, Environmental, Auxiliary, Analytical and Spectra) relationally linked together. The stored information allows for a wide range of analyses and for modelling developments of digital soil mapping applications. An example of partial least-square regression (PLSR) modelling for soil pH and clay content with 0.84 and 0.68 coefficients of determination is provided on the subset of the collected data. Currently, the SSL-CZ database contains more than 500 records in the first phase of development. Spectral reflectance signatures are stored in the range of 350 to 2500 nm with a step of 1 nm measured by ASD FieldSpec 3. The soil spectral library developed is fully compatible with Global Soil Spectral Library (Soil Spectroscopy Group).
13
Gerasimova, М. I., e N. B. Khitrov. "Morphological soil description for classifying soils and interpteting their genesis". Dokuchaev Soil Bulletin 86 (15 dicembre 2016): 8–16. http://dx.doi.org/10.19047/0136-1694-2016-86-8-16.
Testo completo
14
Li, Wentao, Runxiang Li, Yin Chen e Henglin Xiao. "Comparison of Two Sulfate-Bearing Soils Stabilized with Reactive Magnesia-Activated Ground Granulated Blast Furnace Slag: Swelling, Strength, and Mechanism". Buildings 13, n. 1 (13 gennaio 2023): 230. http://dx.doi.org/10.3390/buildings13010230.
Testo completoAbstract (sommario):
Sulfate-bearing soils, which causes many engineering problems, e.g., cracking, collapse, and pavement layer settlement, are often encountered in the construction of pavements. Ground granulated blast furnace slag (GGBS)-magnesia (MgO) has been regarded as an effective curing agent in the treatment of sulfate-bearing soil containing gypsum. However, field sulfate-bearing soils usually include other forms of sulfates, such as sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4). Currently, few studies have investigated the effect of the type of sulfate on the properties of sulfate-bearing soil stabilized with GGBS-MgO. In this study, GGBS-MgO was used to treat Ca-sulfate-soil and Mg-sulfate-soil. Swelling, unconfined compressive strength (UCS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) tests were employed to investigate the properties of the stabilized soils. The results showed that when suitable GGBS:MgO ratios were achieved, the swelling of the two types of sulfate-bearing soils could be well suppressed. However, the trend that the swelling varied with the decrease in the GGBS:MgO ratios was opposite between the two soils. The UCS of Mg-sulfate-soils was much lower than that of the Ca-sulfate-soils after the stabilization of GGBS-MgO irrespective of the curing or soaking stage. CSH significantly occurred in Ca-sulfated soils treated by GGBS-MgO. Ettringite was not observed in the soil with GGBS-MgO = 9:1 but was observed in 6:4. Compared to Ca-sulfate-soils, MSH and less CSH were formed in Mg-sulfate-soils stabilized with GGBS-MgO, which caused the lower strength of the stabilized Mg-sulfate-soils. No ettringite was formed in such soils. Hence, the sulfate type contained in the soils had a significant effect on the swelling and strength properties of sulfate-bearing soils with GGBS-MgO, and so the sulfate needs to be identified before the soil’s stabilization.
15
Lim, B. F., e G. A. Siemens. "Unifying framework for modeling swelling soil behaviour". Canadian Geotechnical Journal 53, n. 9 (settembre 2016): 1495–509. http://dx.doi.org/10.1139/cgj-2015-0049.
Testo completoAbstract (sommario):
The destructive effect of expansive soils on infrastructure is one of the classical issues associated with unsaturated soils. Given the continuing challenges associated with swelling soils there is still a need for a practical analysis method. The swelling equilibrium limit (SEL) provides a concept for modeling expansive soil behaviour. The SEL is an upper bound swelling limit, which depends on the soil’s initial state and the boundary conditions upon wetting. The SEL is obtained experimentally from swelling tests performed by applying a range of swelling scenarios from rigid boundary condition to free swelling without confinement. In this paper, improvements to the triaxial swelling apparatus are reported, SELs for two new swelling soils are characterized, and a framework for SEL prediction is developed. The SEL framework is developed to relate SEL parameters to index properties as well as the soil’s initial volume. SEL parameters are correlated to liquid limit, plasticity index, free swell potential, and specific volume. The relationships are used to estimate the SEL for Regina clay, which is shown to agree with experimental data.
16
Kumar, Ashok. "Use of Leptochloa fusca for the Improvement of Salt-Affected Soils". Experimental Agriculture 32, n. 2 (aprile 1996): 143–49. http://dx.doi.org/10.1017/s0014479700026053.
Testo completoAbstract (sommario):
SUMMARYThe grass Leptocloa fusca is very useful on salt-affected soils as it can tolerate extremely saline and alkaline conditions, Since its growth is not affected by gypsum application, planting with Leptochloa is a good biological method for the reclamation of alkaline soils. It is also well adapted to the waterlogging encountered on saline and alkaline soils, and improves the soil's physical, chemical and biological properties so that within two or three years many commercial and forage crops can be grown. Leptochloa excretes salts through specialized glands and is therefore reasonably palatable to farm animals. Because of its vigorous growth on alkaline soils it does not allow satisfactory growth of companion trees, especially in the initial years of soil reclamation.
17
Novák, Tibor. "Afforestation affects vertical distribution of basic soil characteristics and taxonomic status of sodic soils". Plant, Soil and Environment 68, No. 5 (27 maggio 2022): 245–52. http://dx.doi.org/10.17221/53/2022-pse.
Testo completoAbstract (sommario):
Afforestation, settled before 60–90 years and adjacent solonetzic grasslands, representing the natural vegetation cover were compared in this study based on their basic soil characteristics (pH, CaCO3 content, soil organic carbon (SOC), and exchangeable sodium percentage (ESP)) up to 2 m depth. The assumption was that the plantings of arbour vegetation can change soil characteristics of sodic soils not only in superficial layers but even in larger depths. Grasslands and forest soils were compared by standardised depths. Afforested soils showed lower pH in the depth at 0–100 cm, and slightly higher SOC content in subsoil (20–100 cm). CaCO3 content was significantly different (higher) only at the depth of 50–100 cm in afforested soils. Remarkable differences in ESP values were measured. Afforestation had in almost every layer (0–20, 20–50, 50–100 and 150–200 cm) a significant lower ESP value than grassland soil samples from the same depths. As the value of the ESP is relevant from soil classification purposes as well, the leaching of sodium also can change the taxonomic status of the soils from soils with natric horizon, to soils with Sodic or Bathysodic qualifiers.
18
Mokwenye, Ifesinachi I., Paul N. Diagboya, Bamidele I. Oluowolabi, Ikenna O. Anigbogu e Hilary I. Owamah. "Immobilization of toxic metal cations on goethite-amended soils: a remediation strategy". Journal of Applied Sciences and Environmental Management 20, n. 2 (25 luglio 2016): 436–43. http://dx.doi.org/10.4314/jasem.v20i2.26.
Testo completoAbstract (sommario):
The study investigates a simple and viable option to reduce toxic metals mobility and availability in four surface (0–30cm) soils with varying physicochemical properties amended by different percentages of goethite. Batch sorption experiments carried out to study the effectiveness of immobilizing Pb2+, Cu2+, Zn2+ and Cd2+ ions on these soils showed that goethite played vital role in the metals adsorption (≥10% increase in adsorption). Removal of soil iron oxides caused reduced Pb2+ adsorption on soils with high organic matter (≤ 10% decrease in adsorption) with no significant increase in adsorption upon amendment, while soils having low organic matter had enhanced adsorption with amendment. Cu2+ and Cd2+ adsorptions were not enhanced even at 10% goethite amendment. However, Zn2+ adsorption was interestingly different: the soils showed ≥55 % increases upon removal of inherent soil iron oxides without goethite amendment. Goethite amendments further enhanced Zn2+ adsorption on these soils. Generally, both whole and amended soils showed higher preference for Pb2+; the sorption trend is – Pb2+ >Cu2+ >Zn2+ >Cd2+. Goethite amendment of these soils improved Pb2+ and Zn2+ adsorption. Hence, goethite amendment may be an effective method for immobilizing Pb2+ and Zn2+ on these soils and thus reducing their availability to biota. The quantity of goethite required by a soil to attain maximum immobilization varies depending on the metal and the soil’s physicochemical properties; however, Cu2+ and Cd2+ may not be effectively immobilized using goethite amendment.Keywords: Soil; Goethite; Toxic metals; Adsorption, Remediation
19
Mahdy, A. M. "Comparative effects of different soil amendments on amelioration of saline-sodic soils". Soil and Water Research 6, No. 4 (28 novembre 2011): 205–16. http://dx.doi.org/10.17221/11/2011-swr.
Testo completoAbstract (sommario):
A greenhouse experiment was conducted to test the potential of different soil amendments in saline-sodic soils reclamation; to affect the growth response of alfalfa (Medicago sativa L.) plants grown on two saline-sodic soils; and to evaluate the comparative efficiency of different soil amendments for their effects on salinity, sodicity, and pH levels of the soils. To achieve these objectives, two highly saline-sodic soils were selected (Abees, Typic torrifluvents and Elhammam, Typic calciorthids). Different soil amendments were used (compost, anthracite coal powder, water treatment residuals, ferrous sulphate, and a combination of them). The results of the study indicated that pH of Elhammam soil was less affected than pH of Abees soil after the amendment application because of the high calcium carbonate content which acted as a buffer and resisted any appreciable change in soil pH in the alkaline range. The positive effects of all treatments followed the order: T16 > T12 > T13 > T14 = T5 > T11 = T15 > T7 > T8 > T4 = T6 > T9 = T10 > T2 >T3> T1 >T0. The most effective amendment in reducing SAR<sub>e </sub>in the experimental soils was T16. This was due to the presence of Al in WTRs and Fe in ferrous sulphate which enhanced the leaching process, and the presence of high adsorptive capacity materials like WTRs and compost which adsorb more sodium. The positive effects of all treatments for reducing SAR<sub>e</sub> in Abees soil followed the order: T16 > T15 > T14 > T13 > T11 > T12 .While, in Elhammam soil, the order was: T16 > T15 > T14 > T13 = T11>T12 = T5. The removal sodium efficiency (RSE) or percentage of Na-removed from the soils at the end of the experiment was significantly reduced after the application of the amendments. RSE of T16 proved the highest value (76%) among the treatments for the two soils used, followed by T15 and T14. The yield of biomass at T16 significantly increased, the increase being 959% in comparison with T0 in Abees soil, while the increase in biomass yield was 1452% in comparison with T0 in Elhammam soil. However, field tests are necessary to draw the final conclusions.
20
McCracken, Ralph J. "Soils, Soil Scientists, and Civilization". Soil Science Society of America Journal 51, n. 6 (novembre 1987): 1395–400. http://dx.doi.org/10.2136/sssaj1987.03615995005100060001x.
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Koyluoglu, U. "Soil mechanics for unsaturated soils". Soil Dynamics and Earthquake Engineering 12, n. 7 (1993): 449–50. http://dx.doi.org/10.1016/0267-7261(93)90011-f.
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Bertsch, Floria. "Soil fertility of tropical soils". Soil and Tillage Research 37, n. 2-3 (giugno 1996): 208–9. http://dx.doi.org/10.1016/0167-1987(96)85125-7.
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Tobiašová, E., G. Barančíková, E. Gömöryová, B. Dębska e M. Banach-Szott. "Humus substances and soil aggregates in the soils with different texture". Soil and Water Research 13, No. 1 (24 gennaio 2018): 44–50. http://dx.doi.org/10.17221/31/2017-swr.
Testo completoAbstract (sommario):
Humus substances (HS) influence the incorporation of carbon into soil aggregates in many ways. In this study the influence of HS and their fractions in the soil on the proportions of carbon (total organic, labile, non-labile) in water-resistant macro-aggregates (WSA) and differences between the amount of carbon in WSA in coarse-grained (CGS) and fine-grained (FGS) soils with dependence on the proportions of HS in the soil were determined. The experiment included three soils (Haplic Chernozem, Haplic Luvisol, Eutric Cambisol), each of them with two different soil textures (CGS, FGS) from four ecosystems (forest, meadow, urban, and agro-ecosystem). In CGS, higher proportions (52 and 50%) of smaller (< 1 mm) dry-sieved macro-aggregates (DSA) and also WSA were determined, while in FGS, higher proportions (51 and 53%) of larger DSA (> 7 mm) and WSA (> 2 mm) were detected. A negative correlation was recorded between the content of organic carbon in the fractions of WSA and the amount of extracted humic acids (HA) in CGS, and fulvic acids (FA) in FGS. In CGS, the correlation between the carbon content in WSA and HA bound with Ca<sup>2+</sup> and Mg<sup>2+</sup>, which forms humates (HA2), was negative. In FGS, a negative correlation was recorded between the carbon content in WSA and free aggressive FA (FA1a) and free FA and those, which are bound with monovalent cations and mobile R<sub>2</sub>O<sub>3</sub> (FA1) in the soil. In the case of FA1a, a negative correlation was recorded in FGS and also in CGS, however this influence was more marked in CGS than in FGS (by about 21% higher correlation). In CGS, the influence of HA and FA in soil on the content of labile carbon in aggregates was stronger than in FGS. In CGS, a higher proportion of carbon in aggregates was detected in the case of lower stability of HS and HA and, on the contrary, in FGS, a higher content of carbon in aggregates was detected in the case of their higher stability.
24
Vopravil, J., M. Janeček e M. Tippl. "Revised soil erodibility K-factor for soils in the Czech Republic". Soil and Water Research 2, No. 1 (7 gennaio 2008): 1–9. http://dx.doi.org/10.17221/2100-swr.
Testo completoAbstract (sommario):
In the territory of the Czech Republic there are more than 50% of agricultural soils exposed to water erosion; it is a very urgent problem both at present and for the future. It must be solved now when there is still something to be protected. It is rather complicated to describe the soil properties in terms of soil susceptibility to water erosion because it is a complex relation in which many factors participate. For the complex evaluation of all main factors participating in erosion origination it is possible to apply the Universal Soil Loss Equation (USLE). It consists of six factors interacting with each other and participating in the origination of soil erosion. One of these factors is the soil erodibility factor (K-factor), the revision of which for soil conditions of the CR is the subject of this study. In total ca. 5000 soil pits from the whole territory of the country were processed and evaluated in detail. The main results of this study are K-factor values (means and variances) for the soil types, subtypes and varieties (represented in the database) according to the Taxonomic Classification System of Soils of the Czech Republic.
25
Ghadiri, H., D. Connell e R. Parker. "Sorption-desorption and column leaching of strychnine with soil". Soil Research 38, n. 3 (2000): 603. http://dx.doi.org/10.1071/sr99056.
Testo completoAbstract (sommario):
Sorption–desorption of rodenticide strychnine by soil and its leaching through soil columns were studied on 4 typical soils of south-east Queensland. All 4 soils showed a high tendency to sorb strychnine, with the sorption rate higher for clay soils. The sorption capacities of the 4 soils are in the order Kingsthorpe > Warra > Oakey > Roma, which is also the order of decline in their clay contents. The desorption process also closely followed the clay content of the 4 soils. The 2 clay soils of Kingsthorpe and Warra not only sorbed a higher proportion of the applied strychnine at any application rate, they also showed a greater resistance to releasing their sorbed strychnine compared with the 2 silty clay loam soils. The effects of pH and organic matter content on the sorption–desorption of strychnine were inconclusive due to the dominant influence of clay content and the narrow range of these characteristics provided by the soils under investigation. The 2 clay soils of Kingsthorpe and Warra required a significantly higher number of pore volumes of leaching solution to pass through their respective columns for the concentration of strychnine in the effluent to approach that of the leaching solution, compared with the 2 silty clay soils of Oakey and Roma. The pore volumes of the leaching solution necessary for this point to be reached were not in the order of their clay contents, but when the cumulative volume of solution was used instead of the pore volume, the trend followed the clay content of the soils closely. Pore volume may not be an appropriate characteristic for assessing the leachability of strychnine through soil columns when the soil’s clay fraction is of an expanding type, as it is the case for Kingsthorpe soil. No desorption or leaching of strychnine took place in any of the 4 soils aged with a range of strychnine concentrations.
26
Rakhimgaliyeva, Saule, Sonja Tošić, Frank Eulenstein, Uwe Schindler e Elmira Saljnikov. "How withdrawing arable land affected the productive capacity of Haplic Kastanozems after 19 years of fallowing in dry steppes of the Ural piedmont". Zemljiste i biljka 70, n. 2 (2021): 10–32. http://dx.doi.org/10.5937/zembilj2102010r.
Testo completoAbstract (sommario):
The fertile arable lands in the dry steppe zone of the Ural piedmont, which were intensively used for cereal production for 30 years of the last century, have been withdrawn from cultivation and abandoned for the last 20 years. The Republic of Kazakhstan's new strategy to restore the productivity of natural pasture presents a challenge to scientists when it comes to restoring the natural soil properties to the natural pastoral conditions of the dark chestnut soils studied (Haplic Kastanozems). This chapter presents the results of a project devoted to investigating the changes in the soil's physical and chemical morphology due to the past cultivation history of Haplic Kastanozem soils that have been in a fallow state for the last 19 years. Some changes in the soils' morphological characteristics were caused by the changes in the soils' physical properties due to their past long-term cultivation. The changes observed in the soils' agrochemical characteristics were due to the changes in the soils' physical properties and to the past fertilization history. A minor increase in soil salinity was observed due to the greater accumulation of soluble salts in the arable layer of fallow soil compared to its virgin Haplic Kastanozem analogue. The changes and transitions in the vegetation composition need to be investigated further, and techniques should be developed for the accelerated restoration of fallow soils in dry-steppes of Western Kazakhstan.
27
Kocaman, Kadir, Askin Ozocak, Tuncer B. Edil, Ertan Bol, Sedat Sert, Kurban Onturk e Mustafa Ozsagir. "Evaluation of Soil-Water Characteristic Curve and Pore-Size Distribution of Fine-Grained Soils". Water 14, n. 21 (29 ottobre 2022): 3445. http://dx.doi.org/10.3390/w14213445.
Testo completoAbstract (sommario):
A soil’s physical properties, mineral types, and pore structure significantly influence the shape and properties of the soil-water characteristic curve (SWCC). This study investigated the effects of the soil’s physical properties and mineral types on the SWCC and pore-size distribution (PSD). Eight different soils from an alluvial deposit in Istanbul and Adapazarı/Türkiye were used in the study. The test samples were prepared by compaction at optimum water content (OWC) and wet side of optimum water content (wet of OWC). The samples were prepared by consolidation from the slurry. The PSDs of the samples were calculated using the SWCCs and evaluated with scanning electron microscope (SEM) analysis. In addition, the mineral types of all soils were determined by X-ray diffraction analysis. The soil which contains illite-type minerals has higher matric suction than containing kaolin-type. The effect of the clay percentage is more pronounced in silty soils than in plasticity and activity. Soil suction increased with decreasing compaction water content in clayey soils. The air entry water contents rose as the void ratio, liquid limit, clay content, and plasticity increased. The compaction conditions affected the macropore structure more than the micropore structure. In addition, the ratio of macro-micro pore sizes increased with the rise of the compaction water content.
28
Chakravarthy, Thokala, e K. Shyam Chamberlin. "Fly ash and bagasse ash embankment in flexible pavements for the analysis and strengthening of black cotton soil’s strength stabilized properties". E3S Web of Conferences 391 (2023): 01005. http://dx.doi.org/10.1051/e3sconf/202339101005.
Testo completoAbstract (sommario):
Soil stabilization is necessary to increase the soil’s durability, volume stability, and engineering expansion strength. Expansive soils (also known as black cotton soil), a problem that affects the entire world and poses various challenges for civil engineers, are extremely hard while dry but completely lose their strength when wet. In this study, fly ash has been employed to stabilize the soil. Five, ten, twenty, and twenty-five percent of fly ash was used in the experiments. Bagasse ash is an easily accessible byproduct of the sugar cane refining process that has negative environmental effects. In this study, any potential pozzolanic benefits are evaluated while taking into account bagasse ash. material that stabilizes elongated soil In order to examine the soils’ geotechnical characteristics, the experimental investigation focuses on altering the fly ash content of the soils. The goal is to learn more about the characteristics of black cotton soil’s tensile strength. The primary goal of this research is to examine the effects of bagasse ash on the engineering expansive soil’s properties as revealed by various lab tests, and after improving the treated soil through embankment work at various civil engineering activities, such as roadways.
29
Mori Alvez, Cristina, Carlos Perdomo Varela, Pablo González Barrios, Andrea Bentos Guimaraes e Amabelia del Pino Machado. "Lupine Cultivation Affects Soil’s P Availability and Nutrient Uptake in Four Contrasting Soils". Agronomy 14, n. 2 (18 febbraio 2024): 389. http://dx.doi.org/10.3390/agronomy14020389.
Testo completoAbstract (sommario):
A substantial amount of phosphorus (P) in the soil is not readily available for plant uptake. Certain species may enhance P availability from poorly soluble P forms. This study focused on improving our comprehension of the effect of two lupine species (L. albus and L. angustifolius) on soil’s P mobilization and its link with soil acidity variations, comparing the response of the lupine species in terms of plant traits (i.e., aboveground biomass and nutrient uptake) with that of oats (Avena strigosa L.) in four contrasting soils (i.e., available P in soil, soil acidity, soil fertility, and texture). The phosphorus solubilization capacity was assessed on variations of P availability (PBray1) at four points in time, comparing soils with lupine to oat-containing soils and their baseline values. Compared to soils containing oats, at harvest, lupine soils had significantly increased PBray1 concentrations; the maximum average increment was around 5.3 mg kg−1, with L. albus in Sites 1 and 2, which presented higher organic matter (OM) contents than the other two sites. Lupine-induced soil acidification did not fully explain that P increase. Oats exhibited the highest increase in shoot dry weight in response to soil’s P availability, while lupine was the least affected. Nevertheless, L. albus showed similar or higher nutrient uptake than oats across all soils. The manganese (Mn) concentration was high in both lupine species’ shoot biomass; however, within each lupine species, across all soil types tested, these legumes had different Mn accumulation levels depending on the soil acidity. Lupinus albus had a higher ability to mobilize non-labile P in the light-textured soil with a high OM content, achieving comparable and higher plant P status than oats and providing N through biological N fixation (BNF), positioning it as a suitable crop for diversifying Uruguay’s agricultural crop rotation systems.
30
Williams, Stephen E. "A Review and Analysis of Rangeland and Wildland Soil Health". Sustainability 16, n. 7 (29 marzo 2024): 2867. http://dx.doi.org/10.3390/su16072867.
Testo completoAbstract (sommario):
Soil health is focused on intensively managed (IM) soils (often farmed soils), by-passing extensively managed (EM) soils (range lands, deserts, shrub lands, tundra). High economic value products are generated by IM systems. Many EM lands are of cultural, recreational, scenic, or scientific value. However, and despite the fact that they provide forage for domestic and wild animals, they are not always of high economic value. IM and EM soils are evaluated on the same health scales. The contention herein is all soils formed under soil state conditions under the absence of human interventions are inherently healthy. But a given soil has dynamic properties that determine its management as IM or EM. An EM sagebrush steppe soil may be deemed unhealthy as a result of low organic matter and short growing season. An IM grassland steppe soil is healthy as a result of high organic matter and a long growing season. The sagebrush soil, however, provides habitat for culturally important sage grouse. The grassland soil may provide, when plowed, habitat for economically important soybeans. Soil taxonomies can be used to establish inherent health of undisturbed soils. Determining a soil’s dynamic nature is a different construct. Here, four different sets of EM soils were evaluated to showcase their diversity, evaluate levels of health and display their often-unconventional dynamic characteristics. An argument is made that a soil’s health, an inherent condition, is not the same as its dynamic condition (potential to produce goods and services). Soil health changes are usually slowly driven by soil state factors but can be dramatically changed by humans. Otherwise, soil health can be viewed as a near constant ecosystem attribute. The dynamic nature of soils change according to needs placed by humans. EM soils may be healthy but lack attention since their dynamic nature is not traditional and often of low economic value. Evaluation of soil health and dynamic value on EM lands is often exacerbated by information absence. Strategies to circumvent this include sampling design, reference sites and standardized ways of EM soil health determination. A case is made that baselines of soil health can be taken from soil surveys, taxonomic names, and soil data from map units, where such information exists. Certified supplementary information is ambiguously available, but may be crucial. Outdoor living laboratories that feature inherent soil health and dynamic soil alternatives may help circumvent information voids.
31
Sobti, Dr Jaskiran, e Daljeet Sidhu. "Enhancing California Bearing Ratio through Optimized Compaction Efforts: A Study on Alluvial Soils in North India". Journal of Civil Engineering Frontiers 5, n. 01 (24 febbraio 2024): 1–6. http://dx.doi.org/10.38094/jocef50173.
Testo completoAbstract (sommario):
The quantity of soil required for embankment construction is enormous. Often the soil is brought to the site in dumpers in multiple rounds. This to and from movement of the wagons leads to the deterioration of the existing flexible pavement. In the absence of good earth nearby, using existing soils to act as a subgrade material upon meeting the desired strength and stability characteristics is the need of the hour. The California Bearing Ratio (CBR) is an indicator of soil's strength, which further depends on the degree of compaction of soil. In this study, an effort has been made to find the required compaction efforts to achieve maximum CBR value finding its applicability for both conventional flexible and perpetual pavements. Three different types of alluvial soils in North India were tested for CBR with varying compaction efforts using the modified Proctor test. The effect of mixing different soils was also considered to find the effectiveness of mechanically mixing soils on the required compaction efforts. It was observed that there is a constant upsurge in the CBR of soils upon an increase in the percentage compactive effort up to a certain limit. In the case of clayey soils, the rate of increase is less as compared to the well-graded sands. This study also highlights the effect of mechanical mixing of such soils with sandy soils in desired proportions giving rise to amplified values of CBR ratio of the soil blend. The regression analysis was also conducted to examine a correlation between the compactive effort and CBR values and it was best represented by exponential function for different types of soils.
32
Sierra, C. A., M. Müller e S. E. Trumbore. "Modeling radiocarbon dynamics in soils: SoilR version 1.1". Geoscientific Model Development 7, n. 5 (3 settembre 2014): 1919–31. http://dx.doi.org/10.5194/gmd-7-1919-2014.
Testo completoAbstract (sommario):
Abstract. Radiocarbon is an important tracer of the global carbon cycle that helps to understand carbon dynamics in soils. It is useful to estimate rates of organic matter cycling as well as the mean residence or transit time of carbon in soils. We included a set of functions to model the fate of radiocarbon in soil organic matter within the SoilR package for the R environment for computing. Here we present the main system equations and functions to calculate the transfer and release of radiocarbon from different soil organic matter pools. Similarly, we present functions to calculate the mean transit time for different pools and the entire soil system. This new version of SoilR also includes a group of data sets describing the amount of radiocarbon in the atmosphere over time, data necessary to estimate the incorporation of radiocarbon in soils. Also, we present examples on how to obtain parameters of pool-based models from radiocarbon data using inverse parameter estimation. This implementation is general enough so it can also be used to trace the incorporation of radiocarbon in other natural systems that can be represented as linear dynamical systems.
33
Sierra, C. A., M. Müller e S. E. Trumbore. "Modeling radiocarbon dynamics in soils: SoilR version 1.1". Geoscientific Model Development Discussions 7, n. 3 (7 maggio 2014): 3161–92. http://dx.doi.org/10.5194/gmdd-7-3161-2014.
Testo completoAbstract (sommario):
Abstract. Radiocarbon is an important tracer of the global carbon cycle that helps to understand carbon dynamics in soils. It is useful to estimate rates of organic matter cycling as well as the mean residence or transit time of carbon in soils. We included a set of functions to model the fate of radiocarbon in soil organic matter within the SoilR package for the R environment for computing. Here we present the main system equations and functions to calculate the transfer and release of radiocarbon from different soil organic matter pools. Similarly, we present functions to calculate the mean transit time for different pools and the entire soil system. This new version of SoilR also includes a group of datasets describing the amount of radiocarbon in the atmosphere over time, data necessary to estimate the incorporation of radiocarbon in soils. Also, we present examples on how to obtain parameters of pool-based models from radiocarbon data using inverse parameter estimation. This implementation is general enough so it can also be used to trace the incorporation of radiocarbon in other natural systems that can be represented as linear dynamical systems.
34
Xiao, Jian, Junxian Liu, Siyu Wu, Wenhui Liang e Shangdong Yang. "The Characteristics of the Root-Zone Soil’s Biological Properties and Microbial Community Structure in Grafted Star Anise Plantations". Microorganisms 12, n. 3 (20 febbraio 2024): 431. http://dx.doi.org/10.3390/microorganisms12030431.
Testo completoAbstract (sommario):
Extensive management seriously affects the output, quality, and sustainable development of star anise, and grafting is commonly used to improve its production and quality. Although many studies have explored the effects of grafting on soil microorganisms for other plants, there is a lack of research on aromatic plants, especially on the soil ecosystems of star anise plantations. The effect of grafting star anise on the soil’s biological characteristics and microbial composition remains unclear. The soil’s enzyme activities, soil microbial biomass, and microbial community composition in grafted and non-grafted star anise plantations in Guangxi, China were studied using high-throughput sequencing technology. The results showed that the microbial biomass carbon and phosphorus contents in the soils of grafted star anise were significantly lower and the phosphatase activity was significantly higher than in the soils of non-grafted star anise. In comparison with the soils of non-grafted star anise plantations, the proportions of Proteobacteria, Acidobacteria, Actinobacteria, and WPS-2 decreased and the proportions of Chloroflexi, Planctomycetes, and Verrucomicrobia increased in the grafted star anise plantations. Meanwhile, Bacteroidetes was a dominant bacterial phylum unique to the soil of the grafted star anise plantations. Moreover, the proportions of Ascomycota and Basidiomycota increased and the proportions of Mortierellomycota and unclassified_k_Fungi decreased in the soils of the grafted star anise plantations. Furthermore, Basidiomycota and Rozellomycota had significant dominance in the grafted star anise plantations. In general, grafting can improve soil fertility and maintain soil health by promoting soil nutrient cycling and increasing the soil’s microbial diversity.
35
Hall, Robert D. "A COMPARISON OF SURFACE SOILS AND BURIED SOILS: FACTORS OF SOIL DEVELOPMENT". Soil Science 164, n. 4 (aprile 1999): 264–87. http://dx.doi.org/10.1097/00010694-199904000-00006.
Testo completo
36
Egashira, Kazuhiko, Shoko Tsuda, e Katsutoshi Takuma. "Relation between Soil Properties and the Erodibility of Masa Soils (Granitic Soils)". Soil Science and Plant Nutrition 31, n. 1 (marzo 1985): 105–11. http://dx.doi.org/10.1080/17470765.1985.10555221.
Testo completo
37
Terrones-Saeta, Juan María, Daniel Camazón Portela, Ana Teresa Luís, Jorge Suárez-Macías e José Antonio Grande. "Ceramics for Building Structures Made from Contaminated Soils: A Fuzzy Logic Intelligence Approach to Circular Mining". Processes 11, n. 5 (16 maggio 2023): 1512. http://dx.doi.org/10.3390/pr11051512.
Testo completoAbstract (sommario):
Soils contaminated by mining activities are a major environmental concern, and to avoid this type of environmental impact, carrying out high-cost processes is necessary. For this reason, a solution is proposed in this study in order to eliminate the soils contaminated by mining activities and, in turn, prevent the soil’s contaminating elements from causing harm. All this is achieved by using contaminated soils as raw materials for the production of ceramics for bricks. For this purpose, the materials were initially characterized physically and chemically, and different ceramic test pieces were manufactured with different percentages of clay and contaminated soil, subsequently determining the physical properties and the leaching of toxic elements. In this way, it was possible to evaluate, via innovative data mining and fuzzy logic techniques, the influence of the contaminated soil's contribution on the properties of ceramics. Based on this, it was possible to affirm that the contaminated soil incorporation negatively affects the physical properties of ceramics as well as the leaching of polluting elements. The ceramic formed by contaminated soil and clay has a lower compressive strength, and it is associated with lower linear shrinkage and lower density, as well as higher porosity and cold-water absorption. However, the addition of different percentages of contaminated soil (up to 70%) to clay created a ceramic that complied with regulation restrictions. Therefore, it was possible to obtain a sustainable material that eliminates environmental problems at a lower cost and that fits within the new circular mining concept thanks to fuzzy logic techniques.
38
Anderson, Donald J., Kevin W. Franke, Robert E. Kayen, Shideh Dashti e Mahir Badanagki. "The Over-Prediction of Seismically Induced Soil Liquefaction during the 2016 Kumamoto, Japan Earthquake Sequence". Geosciences 13, n. 1 (27 dicembre 2022): 7. http://dx.doi.org/10.3390/geosciences13010007.
Testo completoAbstract (sommario):
Following the M7.0 strike-slip earthquake near Kumamoto, Japan, in April of 2016, most geotechnical engineering experts believed that there would be significant soil liquefaction and liquefaction-induced infrastructure damage observed in the densely populated city of Kumamoto during the post-event engineering reconnaissance. This belief was driven by several factors including the young geologic environment, alluvially deposited soils, a predominance of loose sandy soils documented in publicly available boring logs throughout the region, and the high intensity ground motions observed from the earthquake. To the surprise of many of the researchers, soil liquefaction occurred both less frequently and less severely than expected. This paper summarizes findings from our field, laboratory, and simplified analytical studies common to engineering practice to assess the lower occurrence of liquefaction. Measured in situ SPT and CPT resistance values were evaluated with current liquefaction triggering procedures. Minimally disturbed samples were subjected to cyclic triaxial testing. Furthermore, an extensive literature review on Kumamoto volcanic soils was performed. Our findings suggest that current liquefaction triggering procedures over-predict liquefaction frequency and effects in alluvially deposited volcanic soils. Volcanic soils were found to possess properties of soil crushability, high fines content, moderate plasticity, and unanticipated organic constituents. Cyclic triaxial tests confirm the high liquefaction resistance of these soils. Moving forward, geotechnical engineers should holistically consider the soil’s mineralogy and geology before relying solely on simplified liquefaction triggering procedures when evaluating volcanic soils for liquefaction.
39
Ahmed, Ahmed, Jiby Kurian e Vijaya Raghavan. "Biochar influences on agricultural soils, crop production, and the environment: A review". Environmental Reviews 24, n. 4 (dicembre 2016): 495–502. http://dx.doi.org/10.1139/er-2016-0008.
Testo completoAbstract (sommario):
Given its high pore volume and adsorption capacity, and when applied as an agricultural soil amendment, its ability to enhance the soil’s nutrient- and water- holding capacities, biochar has become a focus of research interest. In most applications, crop productivity is significantly increased after agricultural soils are amended with biochar. In addition to increasing soil quality, the biochar amendments sequester carbon within the soil. However, the long-term effects of amending agricultural soils with biochar are difficult to predict, because the mechanisms behind the increase in productivity of biochar amended soils are not yet fully understood. Long-term detrimental effects on soil and the environment can occur if biochar is applied haphazardly. Current knowledge and the additional experimental work required to thoroughly understand the influence of biochar amendment on the behavior of agricultural soils processes are reviewed. Further, studies on the post production processing of biochar are discussed in the context of the possible engineering of biochar for particular states of soil degradation.
40
Yasseen, Bassam T., e Roda F. Al-Thani. "Endophytes and Halophytes to Remediate Industrial Wastewater and Saline Soils: Perspectives from Qatar". Plants 11, n. 11 (2 giugno 2022): 1497. http://dx.doi.org/10.3390/plants11111497.
Testo completoAbstract (sommario):
Many halophytes are considered to be salt hyperaccumulators, adopting ion extrusion and inclusion mechanisms. Such plants, with high aboveground biomass, may play crucial roles in saline habitats, including soil desalination and phytoremediation of polluted soils and waters. These plants cause significant changes in some of the soil’s physical and chemical properties; and have proven efficient in removing heavy metals and metabolizing organic compounds from oil and gas activities. Halophytes in Qatar, such as Halopeplis perfoliata, Salicornia europaea, Salsola soda, and Tetraena qatarensis, are shown here to play significant roles in the phytoremediation of polluted soils and waters. Microorganisms associated with these halophytes (such as endophytic bacteria) might boost these plants to remediate saline and polluted soils. A significant number of these bacteria, such as Bacillus spp. and Pseudomonas spp., are reported here to play important roles in many sectors of life. We explore the mechanisms adopted by the endophytic bacteria to promote and support these halophytes in the desalination of saline soils and phytoremediation of polluted soils. The possible roles played by endophytes in different parts of native plants are given to elucidate the mechanisms of cooperation between these native plants and the associated microorganisms.
41
Li, Z., e F. M. Kelliher. "Determining nitrous oxide emissions from subsurface measurements in grazed pasture: A field trial of alternative technology". Soil Research 43, n. 6 (2005): 677. http://dx.doi.org/10.1071/sr04106.
Testo completoAbstract (sommario):
Beneath pasture grazed by farmed animals, the soil’s nitrogen (N), oxygen, and temperature regimes can be unevenly distributed in time and space. It is difficult to capture spatial and temporal variation of N2O using conventional emission measurement technology based on gas samples taken in chambers that briefly cover a small area of the soil’s surface. We report the results from field deployment of alternative, non-intrusive N2O emission measurement technology that uses subsurface measurements incorporating the soil processes controlling the net N2O production and gas diffusion rates. During 100 autumn and winter days after dairy cattle urine was applied (650 kg N/ha) to freely and poorly drained pastoral soils near Hamilton, New Zealand (37.8° S, 175.3° E), N2O emissions were determined. The measured values ranged from 0.024 to 1.55 and 0.048 to 3.33 mg N2O-N/m2.h for the freely and poorly drained soils, respectively. Over the 100 days, it was estimated that 0.4 and 1.3% of the applied N was directly emitted to the atmosphere as N2O from the freely and poorly drained soils, respectively.
42
van Mansvelt, Jan Diek, Paul C. Struik, Arie Bos, Willem Daub, Diederick Sprangers, Mara van den Berg, Marieke Vingerhoets e Kees Zoeteman. "Changing Ground: Handling Tensions between Production Ethics and Environmental Ethics of Agricultural Soils". Sustainability 13, n. 23 (1 dicembre 2021): 13291. http://dx.doi.org/10.3390/su132313291.
Testo completoAbstract (sommario):
Soils are an essential element in sustainable food systems and vital for ecosystem services. Soils are degrading, because of urbanization, poor soil management, depletion and mining, over-use of inputs and impacts of climate change. Poor soil management resulted from short-term yield maximization caused by changes in land tenure, property rights and land use. We argue for soil protection based on the concept of soil telos defined as the combined purposefulness in agricultural production and terrestrial ecosystem optimization. It includes the right of mankind to use soils, provided norms and values are respected based on the soil’s usefulness, its natural purposefulness and its right to be protected (including its physical, chemical and biological cycles). Finding a sustainable balance between these values and rights on the one hand and the need to use living soils for agricultural production on the other hand requires a new approach to soil management based on widely accepted norm- and value-driven decisions on unavoidable trade-offs. Reconciling man-made telos and natural telos, requires (i) empowering the soil to achieve its man-made telos (e.g., by restoring degraded soils); (ii) empowering the soil to achieve its natural telos (e.g., by restoring water courses); (iii) raising awareness about the need to reconcile these two teloi (e.g., by acknowledging rights of soils); and (iv) monitoring tools to assess successful reconciliation (e.g., by evaluating soil health).
43
Świdziński, Waldemar, Jacek Mierczyński e Agata Mikos. "Response of Partially Saturated Non-cohesive Soils". Archives of Hydro-Engineering and Environmental Mechanics 64, n. 3-4 (1 dicembre 2017): 187–207. http://dx.doi.org/10.1515/heem-2017-0012.
Testo completoAbstract (sommario):
AbstractThis paper analyses and discusses experimental results of undrained triaxial tests. The tests were performed on non-cohesive partially saturated soil samples subjected to monotonic and cyclic loading. The tests were aimed at determining the influence of saturation degree on soil’s undrained response (shear strength, excess pore pressure generation). The saturation of samples was monitored by checking Skempton’s parameter B. Additionally, seismic P-wave velocity measurements were carried out on samples characterized by various degrees of saturation. The tests clearly showed that liquefaction may also take place in non-cohesive soils that are not fully saturated and that the liquefaction potential of such soils strongly depends on the B parameter.
44
Jiang, Yingying, Zhongxiu Sun, Yubo Zheng, Hongling Wang e Jiaqing Wang. "Establishing a Soil Health Assessment System for Quaternary Red Soils (Luvisols) under Different Land Use Patterns". Agronomy 13, n. 8 (30 luglio 2023): 2026. http://dx.doi.org/10.3390/agronomy13082026.
Testo completoAbstract (sommario):
The health status of Quaternary red soil is a comprehensive reflection of the production and ecological service functions, which directly affects agricultural productivity and ecosystem sustainability. Based on the Cornell Soil Health Assessment (CASH) system frame, a health evaluation system for Quaternary red soils was established including the soil’s physical, chemical, and biological indicators. The soil’s health status under different land use patterns (the buried Quaternary red soil, sparse forest and grassland, grassland, woodland, and arable land) was systematically diagnosed in the low hilly region of western Liaoning Province. The results showed significant differences in the soil health comprehensive index of the Quaternary red soils under different land use patterns (the whole soil), presenting a trend of woodland (0.64) > arable land (0.61) > grassland (0.49) > sparse forest and grassland (0.37) > buried Quaternary red soils (0.33). The woodland and arable land are at a healthy level, the grassland and sparse forest and grassland are at a sub-healthy level, and the buried Quaternary red soil is at an unhealthy level. The health status of the topsoil layer (A) under different land use patterns has a trend of woodland (0.86) > arable land (0.73) > grassland (0.70) > sparse forest and grassland (0.67). This is consistent with the overall health status of the profile, better than that of subsoil layer (B), which presents a trend of arable land (0.41) > grassland (0.40) > woodland (0.38) > sparse forest and grassland (0.34), with relatively poor soil health conditions. Overall, the soil health status of the four land use patterns is better than that of the buried Quaternary red soils, showing an evolution trend towards healthy soil. This indicates that at this stage, human land use activities have to some extent promoted the healthy development of Quaternary red soils. The Quaternary red soils of the woodland have a healthy status, and the land use pattern is suitable and can be scientifically recommended in low mountain and hilly areas.
45
Behrens, T., K. Gregor e W. Diepenbrock. "Separation of soil and canopy reflectance signatures of Mid German agricultural soils". Plant, Soil and Environment 51, No, 7 (19 novembre 2011): 296–303. http://dx.doi.org/10.17221/3589-pse.
Testo completoAbstract (sommario):
Remote sensing can provide visual indications of crop growth during production season. In past, spectral optical estimations were well performed in the ability to be correlated with crop and soil properties but were not consistent within the whole production season. To better quantify vegetation properties gathered via remote sensing, models of soil reflectance under changing moisture conditions are needed. Signatures of reflected radiation were acquired for several Mid German agricultural soils in laboratory and field experiments. Results were evaluated at near-infrared spectral region at the wavelength of 850 nm. The selected soils represented different soil colors and brightness values reflecting a broad range of soil properties. At the wavelength of 850 nm soil reflectance ranged between 10% (black peat) and 74% (white quartz sand). The reflectance of topsoils varied from 21% to 32%. An interrelation was found between soil brightness rating values and spectral optical reflectance values in form of a linear regression. Increases of soil water content from 0% to 25% decreased signatures of soil reflectance at 850 nm of two different soil types about 40%. The interrelation of soil reflectance and soil moisture revealed a non-linear exponential function. Using knowledge of the individual signature of soil reflectance as well as the soil water content at the measurement, soil reflectance could be predicted. As a result, a clear separation is established between soil reflectance and reflectance of the vegetation cover if the vegetation index is known.
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Campora, Marina, Anna Palla, Ilaria Gnecco, Rossella Bovolenta e Roberto Passalacqua. "The laboratory calibration of a soil moisture capacitance probe in sandy soils". Soil and Water Research 15, No. 2 (11 marzo 2020): 75–84. http://dx.doi.org/10.17221/227/2018-swr.
Testo completoAbstract (sommario):
Determining and mitigating landslide risk is a technical-scientific objective, particularly for the protection and proper territorial management and planning. The slope stability depends on the pore pressure distribution, which is influenced by the saturation front propagation through the unsaturated zone, whose monitoring is useful to understand any possible instabilities. Such monitoring may be undertaken by sensors based on the measurement of the relative dielectric permittivity. Reliable relationships between the measurement and the soil moisture are necessary. The main objective of this study is to assess a laboratory calibration protocol for a specific capacitance sensor (Drill & Drop, Sentek Sensor Technologies). Two monogranular sands have been selected for the calibration purpose. The laboratory tests were performed under three relative density values (D<sub>R</sub> equal to 40%, 60% and 80%) for seven volumetric water content values (θ<sub>v</sub> ranging from 0.00% to 36.26%). Based on the experimental measurements, the soil-specific calibration curves were determined at an assigned relative density value; in particular, a simple power law is adopted to describe the probe’s reading as a function of the volumetric water content. The results point out that the relative density values slightly affect the tests, thus, the soil-specific calibration curves are derived based on a simple regression analysis fitting the whole set of the laboratory tests validated for each sand. The calculated coefficient of determination (R<sup>2</sup> = 0.96÷0.99) and root mean square error (RMSE = 1.4%÷2.8%) values confirm the goodness of fit. In order to propose more general fitting curves, suitable for both the investigated sands, multiple linear regressions are performed by considering θ<sub>v</sub> and the mean grain size, D<sub>50</sub> as independent variables; again, the R<sup>2</sup> and RMSE values equal to 0.97 and 2.41%, respectively, confirm the suitability of the calibration curve. Finally, the laboratory calibration curves are compared with the manufacturer-supplied curves, thus, enhancing the need for the soil-specific calibration.
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Vásquez-Nogal, Ismael, Christian E. Hernández-Mendoza, Arely I. Cárdenas-Robles e Eduardo Rojas-González. "Estimating the Soil-Water Retention Curve of Arsenic-Contaminated Soil by Fitting Fuentes’ Model and Their Comparison with the Filter Paper Method". Applied Sciences 12, n. 15 (3 agosto 2022): 7793. http://dx.doi.org/10.3390/app12157793.
Testo completoAbstract (sommario):
Arsenic is a metalloid frequently found in contaminated sites, especially in the soil. In this regard, soil contamination has attracted researchers’ attention because it affects soil suction, which is essential in unsaturated soil mechanics. Due to its reliability and low cost, the filter paper method is frequently used to evaluate soil suction. However, it is laborious and time consuming. As an alternative, different mathematical models have been developed to estimate natural soil’s suction. The objective of this study was to elucidate if Fuentes’ model (using fractal, Mualem, and Burdine restrictions) can be used to estimate the soil-water retention curve of an arsenic-contaminated soil by comparing it with the filter paper method data already reported. The results showed that under natural conditions, Fuentes’ model provided similar results to those obtained by the filter paper method. The model also suggested modification of the soil’s structure, observed by the increase in the soil’s particle diameter after contamination. However, Fuentes’ model was observed to overestimate the suction values for contaminated soils. This observation highlights the necessity to use a soil stabilization method to control the soil’s volume variations. The data also showed that Fuentes’ model overestimated the hydraulic conductivity function of the contaminated soil. Hence, the retention potential does not reflect the behavior of the contaminated soils and can induce misinterpretation of contaminant transport evaluation in soil. Nevertheless, further analyses should be performed to investigate the direct applicability of this model to soils contaminated with other substances.
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Watts, Frank C. "Collecting Soil Monoliths In Sandy Soils". Soil Horizons 34, n. 4 (1993): 105. http://dx.doi.org/10.2136/sh1993.4.0105.
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Landsburg, S., e A. Fedkenheuer. "Reclamation of Soil Sterilant Contaminated Soils". Journal American Society of Mining and Reclamation 1990, n. 1 (1990): 437–44. http://dx.doi.org/10.21000/jasmr90010437.
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Landsburg, S., e A. W. Fedkenheuer. "RECLAMATION OF SOIL STERILANT CONTAMINATED SOILS". Journal American Society of Mining and Reclamation 1990, n. 2 (1990): 437–44. http://dx.doi.org/10.21000/jasmr90020437.
Testo completo