To see the other types of publications on this topic, follow the link: Soil physics. Soils.
Journal articles on the topic 'Soil physics. Soils'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Soil physics. Soils.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Allbrook, RF. "Shrinkage of some New Zealand soils and its implications for soil physics." Soil Research 31, no. 2 (1993): 111. http://dx.doi.org/10.1071/sr9930111.
Full textAbstract:
Aggregates from three New Zealand soils were used to produce shrinkage curves. Each soil had a clay mineralogy dominated by a different mineral, namely allophane, halloysite and kaolinite.The curves showed marked differences. Only the allophanic soil showed structural shrinkage, and only the halloysitic soil showed residual shrinkage. When the slope of the normal shrinkage line is about unity, this indicates the soil is liable to crack- this was only shown by the allophanic soil. The implication for soil physics is that, since all soils with at least a moderate clay content shrink, bulk densities change with moisture and this must be allowed for in such calculations as soil moisture on a volume basis.
2
Richards, BG. "The role of lateral stresses on soil water relations in swelling clays." Soil Research 24, no. 4 (1986): 457. http://dx.doi.org/10.1071/sr9860457.
Full textAbstract:
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.
3
Nofziger, David L., and Jinquan Wu. "Soil Physics Teaching Tools: Steady-State Water Movement in Soils." Journal of Natural Resources and Life Sciences Education 29, no. 1 (2000): 130–34. http://dx.doi.org/10.2134/jnrlse.2000.0130.
Full text
4
Rehman, Obaid ur, Shahzada Munawar Mehdi, Raja Abad, Shahid Saleem, Rizwan Khalid, Sarosh Tariq Alvi, and Asia Munir. "Soil Characteristics and Fertility Indexation in Gujar Khan Area of Rawalpindi." Pakistan Journal of Scientific & Industrial Research Series A: Physical Sciences 64, no. 1 (March 1, 2021): 46–51. http://dx.doi.org/10.52763/pjsir.phys.sci.64.1.2021.46.51.
Full textAbstract:
Soil characteristics of Gujar Khan area of Rawalpindi district were evaluated through physical and chemical analysis. About 3002 soil samples were received/collected from farmers' fields of Gujar Khan during the period between 2012 and 2017 and analysed for texture, electrical conductivity (ECe), pH, organic matter (OM), available phosphorus (AP) and available potash (AK). The analysis results revealed that texture of the soils varied from sandy loam (33.5%) to loam (61.6%). The 98.6% soils had ECe values within the normal range (< 4 dS/m) and almost 74% soil had from 7.5 to 8.5 pH values with an average of 7.76. Thus there was no salinity/alkanity hazard in the area. Generally most of the soils were poor from the fertility point of view. About 96% soils were poor in both OM and AP contents, whereas, 3.0% soils have OM (>0.86%) and 3.4% satisfactory levels and AP (>7.0-14 mg/Kg). However, 62% soils has satisfactory to adequate AK status. The frequency distribution analysis indicated that 45% soils of Gujar Khan and OM content in the range of 0.4-0.6%, 57% and soil have AP in the range of 4.0-6.0 mg/Kg, while 50% and AK in the range of 81-120 mg/Kg. The soil fertility indexes in respect of OM and AP were low (1.0), whereas AK (1.7) indicating a medium fertility status of Gujar Khan soils.
5
Gliński, Jan, Józef Horabik, and Jerzy Lipiec. "Agrophysics - physics in agriculture and environment." Soil Science Annual 64, no. 2 (August 1, 2013): 67–80. http://dx.doi.org/10.2478/ssa-2013-0012.
Full textAbstract:
Abstract Agrophysics is one of the branches of natural sciences dealing with the application of physics in agriculture and environment. It plays an important role in the limitation of hazards to agricultural objects (soils, plants, agricultural products and foods) and to the environment. Soil physical degradation, gas production in soils and emission to the atmosphere, physical properties of plant materials influencing their technological and nutritional values and crop losses are examples of such hazards. Agrophysical knowledge can be helpful in evaluating and improving the quality of soils and agricultural products as well as the technological processes.
6
De Deyn, Gerlinde B., and Lammert Kooistra. "The role of soils in habitat creation, maintenance and restoration." Philosophical Transactions of the Royal Society B: Biological Sciences 376, no. 1834 (August 4, 2021): 20200170. http://dx.doi.org/10.1098/rstb.2020.0170.
Full textAbstract:
Soils are the fundament of terrestrial ecosystems. Across the globe we find different soil types with different properties resulting from the interacting soil forming factors: parent material, climate, topography, organisms and time. Here we present the role of soils in habitat formation and maintenance in natural systems, and reflect on how humans have modified soils from local to global scale. Soils host a tremendous diversity of life forms, most of them microscopic in size. We do not yet know all the functionalities of this diversity at the level of individual taxa or through their interactions. However, we do know that the interactions and feedbacks between soil life, plants and soil chemistry and physics are essential for soil and habitat formation, maintenance and restoration. Moreover, the couplings between soils and major cycles of carbon, nutrients and water are essential for supporting the production of food, feed and fibre, drinking water and greenhouse gas balances. Soils take thousands of years to form, yet are lost very quickly through a multitude of stressors. The current status of our soils globally is worrisome, yet with concerted action we can bend the curve and create win–wins of soil and habitat conservation, regeneration and sustainable development. This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.
7
Zhao, Litong, D. M. Gray, and B. Toth. "Influence of soil texture on snowmelt infiltration into frozen soils." Canadian Journal of Soil Science 82, no. 1 (February 1, 2002): 75–83. http://dx.doi.org/10.4141/s00-093.
Full textAbstract:
This paper describes the influence of soil texture on snowmelt infiltration into frozen soils. Field data collected on frozen, unsaturated agricultural soils of the Canadian Prairies during snow ablation demonstrate: (a) poor association between the amount of infiltration of meltwater released by the seasonal snowcover and soil texture, and (b) small differences in cumulative amounts among soils of widely different textures. A physics-based numerical simulation of heat and mass transfers with phase changes in frozen soils is used to study the mechanics of the infiltration process in representative clay, silty clay loam, silt loam and sandy loam soils. The results of the simulations show that the differences among cumulative snowmelt infiltration into clay, silty clay loam and silt loam soils after 24 h of continuous infiltration are small. Infiltration into a lighter-textured sandy loam after 24 h was on average 23% higher than in the other three soils with most of the increase occurring in the first 5 h of the simulation. Key Words: Soil texture, snowmelt, infiltration, frozen soils
8
Pham, Hung Q., and Delwyn G. Fredlund. "Volume–mass unsaturated soil constitutive model for drying–wetting under isotropic loading–unloading conditions." Canadian Geotechnical Journal 48, no. 2 (February 1, 2011): 280–313. http://dx.doi.org/10.1139/t10-061.
Full textAbstract:
A rigorous volume–mass constitutive model is proposed for the representation of drying–wetting under isotropic loading–unloading conditions for unsaturated soils. The proposed model utilizes concepts arising from soil physics and geotechnical engineering research and requires readily obtainable soils data for soil properties. The model can be used to predict void ratio and water content constitutive relationships (and therefore degree of saturation) for a wide range of unsaturated soils. Various stress paths (i.e., loading–unloading and drying–wetting) can be simulated, and hysteresis associated with the soil-water characteristic curve is taken into account. Two closed-form equations for the volume–mass constitutive relationships are presented for soils starting from slurry conditions. A number of test results (i.e., from experimental programs reported in the research literature) were used during the verification of the proposed volume–mass constitutive model. The volume–mass constitutive model captures key unsaturated soil conditions such as air-entry value, water-entry value, and residual conditions. The proposed model appears to satisfactorily predict unsaturated soil behavior for soils ranging from low compressible sands to high compressible clays.
9
Hartmann, Anne, Markus Weiler, and Theresa Blume. "The impact of landscape evolution on soil physics: evolution of soil physical and hydraulic properties along two chronosequences of proglacial moraines." Earth System Science Data 12, no. 4 (December 4, 2020): 3189–204. http://dx.doi.org/10.5194/essd-12-3189-2020.
Full textAbstract:
Abstract. Soil physical properties highly influence soil hydraulic properties, which define the soil hydraulic behavior. Thus, changes within these properties affect water flow paths and the soil water and matter balance. Most often these soil physical properties are assumed to be constant in time, and little is known about their natural evolution. Therefore, we studied the evolution of physical and hydraulic soil properties along two soil chronosequences in proglacial forefields in the Central Alps, Switzerland: one soil chronosequence developed on silicate and the other on calcareous parent material. Each soil chronosequence consisted of four moraines with the ages of 30, 160, 3000, and 10 000 years at the silicate forefield and 110, 160, 4900, and 13 500 years at the calcareous forefield. We investigated bulk density, porosity, loss on ignition, and hydraulic properties in the form of retention curves and hydraulic conductivity curves as well as the content of clay, silt, sand, and gravel. Samples were taken at three depths (10, 30, 50 cm) at six sampling sites at each moraine. Soil physical and hydraulic properties changed considerably over the chronosequence. Particle size distribution showed a pronounced reduction in sand content and an increase in silt and clay content over time at both sites. Bulk density decreased, and porosity increased during the first 10 millennia of soil development. The trend was equally present at both parent materials, but the reduction in sand and increase in silt content were more pronounced at the calcareous site. The organic matter content increased, which was especially pronounced in the topsoil at the silicate site. With the change in physical soil properties and organic matter content, the hydraulic soil properties changed from fast-draining coarse-textured soils to slow-draining soils with high water-holding capacity, which was also more pronounced in the topsoil at the silicate site. The data set presented in this paper is available at the online repository of the German Research Center for Geosciences (GFZ; Hartmann et al., 2020b). The data set can be accessed via the DOI https://doi.org/10.5880/GFZ.4.4.2020.004.
10
Ermolin, M. S., and N. N. Fedyunina. "MOBILITY OF CERIUM DIOXIDE NANOPARTICLES IN SOILS AT DIFFERENT EXPOSURE SCENARIOS." Industrial laboratory. Diagnostics of materials 85, no. 5 (June 5, 2019): 5–10. http://dx.doi.org/10.26896/1028-6861-2019-85-5-5-10.
Full textAbstract:
Nowadays, widespread application of engineered nanoparticles (ENPs) inevitably leads to their release into the environment. Soils are regarded as the ultimate sink for ENPs. The study on the mobility of ENPs in soils is important in the assessment of potential risks related to their toxicity. The behavior of ENPs depends not only on the parameters of soil, but also on the exposure scenarios, namely, the amount of ENPs trapped in soil. We studied the mobility of cerium dioxide nanoparticles (nCeO2) in soils at different exposure scenarios. The relationship between the mobility of nCeO2and their concentration in the soil within the range 1 – 1000 ìg/g is evaluated. It is shown that the mobility of nCeO2decreases with a decrease in their concentration in the soil and attains the minimum value when the concentration of nCeO2goes below 10 ìg/g. In relative units, only about 0.1 – 0.2% of nCeO2(in aforementioned concentration range) exhibit mobility and can migrate in the soil profile under saturated conditions. The lion’s share of nCeO2(about 99.8%) remains immobile in the soil. Evidently, the vertical transport of nCeO2in soil profile should depend on the volume of released suspensions. In the case of small or moderate wet deposition, nanoparticles will accumulate in upper soil horizons characterized with the highest biological activity and thus can affect the soil inhabitants (plant roots, earthworms, insects, microorganisms, etc.).
11
Benvenuti, Stefano, and Marco Mazzoncini. "Soil Physics Involvement in the Germination Ecology of Buried Weed Seeds." Plants 8, no. 1 (December 29, 2018): 7. http://dx.doi.org/10.3390/plants8010007.
Full textAbstract:
Trials were performed to test the germination ecology of buried weed seeds as a function of physical soil conditions such as of burial depth, texture, and compaction. Indeed, these ecological conditions, due to the adopted agronomic practices, play a crucial role in modulating the seed bank germination dynamics. Experiments were carried out in open fields in confined soils (polypropylene pipes), and in the laboratory in Petri dishes. Sowing depth strongly inhibited the seed germination of the three weed species selected. This inhibition was found to be inversely proportional to the size of the soil particles. Compaction strongly increased the depth-mediated inhibition, especially in soils that were rich in clay particles, and was inversely proportional to the seed size. The physiological nature of the dormancy imposed by burial was investigated. In addition, ungerminated seeds, re-exhumed after deep-sowing for six months, were found to be in deep dormancy, especially after burial in compacted clay soil. This dormancy induction was more pronounced in weed species characterized by small seeds. Critical issues are discussed regarding weed seed bank ecophysiology and their management in sustainable agricultural cropping systems.
12
Arenson, Lukas U., Sarah M. Springman, and Dave C. Sego. "The Rheology of Frozen Soils." Applied Rheology 17, no. 1 (February 1, 2007): 12147–1. http://dx.doi.org/10.1515/arh-2007-0003.
Full textAbstract:
Abstract The rheological behaviour of frozen soils depends on a number of factors and is complex. Stress and temperature histories as well as the actual composition of the frozen soil are only some aspects that have to be considered when analysing the mechanical response. Recent improvements in measuring methods for laboratory investigations as well as new theoretical models have assisted in developing an improved understanding of the thermo-mechanical processes at play within frozen soils and representation of their response to a range of perturbations. This review summarises earlier work and the current state of knowledge in the field of frozen soil research. Further, it presents basic concepts as well as current research gaps. Suggestions for future research in the field of frozen soil mechanics are also made. The goal of the review is to heighten awareness of the complexity of processes interacting within frozen soils and the need to understand this complexity when developing models for representing this behaviour.
13
Hallet, Bernard. "Self-organization in freezing soils: from microscopic ice lenses to patterned ground." Canadian Journal of Physics 68, no. 9 (September 1, 1990): 842–52. http://dx.doi.org/10.1139/p90-122.
Full textAbstract:
Freezing in moist fine-grained soils is a highly nonhomogeneous process. It involves transport of water to freezing sites and growth of distinct ice bodies separated by soil domains free of ice. On a much larger scale, recurrent ice growth and thawing of cold regions produce a rich diversity of patterns in soils; these patterns can be defined by local relief, soil cracks, or segregation of mineral material according to size. This paper reviews the principal spatial structures characteristic of freezing soils and discusses the underlying processes in the broader context of geomorphic self-organization.
14
Nagare, R. M., P. Bhattacharya, J. Khanna, and R. A. Schincariol. "Coupled cellular automata for frozen soil processes." SOIL Discussions 1, no. 1 (May 21, 2014): 119–50. http://dx.doi.org/10.5194/soild-1-119-2014.
Full textAbstract:
Abstract. Heat and water movement in variably saturated freezing soils is a tightly coupled phenomenon. Strong coupling of water and heat movement in frozen soils moves considerable amounts of water from warmer to colder zones. The coupling is a result of effects of sub-zero temperature on soil water potential, heat carried by water moving under pressure gradients, and dependency of soil thermal and hydraulic properties on soil water content. This makes water and heat movement in variably saturated soils a highly non-linear process in mathematical terms. This study presents a one-dimensional cellular automata (direct solving) model to simulate coupled heat and water transport with phase change in variably saturated soils. The model is based on first order mass and energy conservation principles. The water and energy fluxes are calculated using first order empirical forms of Buckingham–Darcy's law and Fourier's heat law, respectively. The water-ice phase change is handled by integrating along experimentally determined soil freezing curve (unfrozen water content and temperature relationship) obviating the use of apparent heat capacity term. This approach highlights a further subtle form of coupling one in which heat carried by water perturbs the water content – temperature equilibrium and exchange energy flux is used to maintain the equilibrium rather than affect temperature change. The model is successfully tested against analytical and experimental solutions. Setting up a highly non-linear coupled soil physics problem with a physically based approach provides intuitive insights into an otherwise complex phenomenon.
15
Li, Wugang, Wenhua Liu, Zhijia Xue, and Xiuli Sun. "A Constitutive Model for Overconsolidated Structured Soils Using Structural Variable." Shock and Vibration 2021 (August 9, 2021): 1–14. http://dx.doi.org/10.1155/2021/5530038.
Full textAbstract:
Due to the influence of soil structure, structured soils exhibit significantly different mechanical behavior compared to the reconstituted soils having the same material. In this work, a theoretical analysis focusing on the mechanical behavior of structured soils is presented. Based on the mechanical behavior of the structured soil, a newly defined variable structural index was used as a measurement of the integrity of soil structure based on the concept of intrinsic compression line of intact structured soils. Furthermore, a novel correlation for the variation in volume of structured soils is established using effective stress and newly defined structural index as the constitutive variables. The novel correlation provided interpretation about the mechanism of compression behavior of the structured soils. Afterwards, the proposed correlation for the variation in volume was extended to triaxial stress state in the framework of subloading surface to include the effect of overconsolidation. Comparisons between the predictions and experimental results validated the proposed constitutive model for structured soils.
16
LI, SHOUJU, and YINGXI LIU. "PARAMETER IDENTIFICATION APPROACHES TO FRACTAL MODEL OF MASS TRANSPORT FOR UNSATURATED SOILS." Modern Physics Letters B 19, no. 28n29 (December 20, 2005): 1727–30. http://dx.doi.org/10.1142/s0217984905010323.
Full textAbstract:
Modeling flow and solute transport in the unsaturated zone requires specifying values for soil hydraulic conductivity. Fractal models describe hierarchical systems and are suitable to model soil structure and soil hydraulic properties. The objectives of the paper are to propose a parameter identification approach and to determine hydraulic parameters using inverse modeling. The inverse problem of parameter identification is formulated as an optimization problem. In order to identify hydraulic parameters of soils efficiently and in a robust manner, the genetic algorithm is presented for the parameter identification of the fractal models. The investigation shows that the proposed inversion procedure is more superior for applying to parameter identification of fractal model of mass transport for unsaturated soils.
17
Onojake, Mudiaga Chukunedum, and Selegha Abrakasa. "Effects of Crude Oil Inundated Soils on the Ecosystem A Case Study." Pakistan Journal of Scientific & Industrial Research Series A: Physical Sciences 60, no. 2 (June 29, 2017): 106–13. http://dx.doi.org/10.52763/pjsir.phys.sci.60.2.2017.106.113.
Full textAbstract:
Crude oil inundated soils were collected from Agbada field after a recorded incidence of oil spillageto ascertain the effects of the oil spill on the soil status. Soil samples were collected from (0-30 cm) depths,using the grid sampling technique. Total petroleum hydrocarbon content (TPH) of the impacted soils rangedfrom 1.81541×103-4.8525040×103 mg/kg. The levels of total organic carbon (%TOC), pH, conductivity,sulphates, nitrates and phosphates were enhanced in impacted soil. The concentration of some trace metalssuch as Cd, Cu, Cr, Pb, Ni, Fe and V were also analysed using atomic absorption spectroscopy. Cd rangedfrom 0.2-0.38 mg/kg, Cu ranged from 4.20-5.20 mg/kg, Cr ranged from 18.40-44.40 mg/kg, Pb rangedfrom 1.20-30.40 mg/kg, Ni ranged from 2.40-2.70 mg/kg, Fe ranged from 17581.77-30273.25 mg/kg andV ranged 0.20-0.30 mg/kg. Most of the trace metals were highly enhanced in the impacted soil. Multivariatestatistical analysis was carried out on the dataset to unveil the variation and relationship among them.Results showed that the first three principal components with the eigen values greater than one (>1.0)represent 93.4% of the total variability, suggesting that three principal components effectively describethe disparity in the data set. It was concluded that soils impacted with high hydrocarbon content; ultimatelyaffect its physicochemical characteristics, which in turn impinge on the agricultural potentials of the soil.
18
González-Teruel, Juan D., Scott B. Jones, Fulgencio Soto-Valles, Roque Torres-Sánchez, Inmaculada Lebron, Shmulik P. Friedman, and David A. Robinson. "Dielectric Spectroscopy and Application of Mixing Models Describing Dielectric Dispersion in Clay Minerals and Clayey Soils." Sensors 20, no. 22 (November 22, 2020): 6678. http://dx.doi.org/10.3390/s20226678.
Full textAbstract:
The number of sensors, ground-based and remote, exploiting the relationship between soil dielectric response and soil water content continues to grow. Empirical expressions for this relationship generally work well in coarse-textured soils but can break down for high-surface area and intricate materials such as clayey soils. Dielectric mixing models are helpful for exploring mechanisms and developing new understanding of the dielectric response in porous media that do not conform to a simple empirical approach, such as clayey soils. Here, we explore the dielectric response of clay minerals and clayey soils using the mixing model approach in the frequency domain. Our modeling focuses on the use of mixing models to explore geometrical effects. New spectroscopic data are presented for clay minerals (talc, kaolinite, illite and montmorillonite) and soils dominated by these clay minerals in the 1 MHz–6 GHz bandwidth. We also present a new typology for the way water is held in soils that we hope will act as a framework for furthering discussion on sensor design. We found that the frequency-domain response can be mostly accounted for by adjusting model structural parameters, which needs to be conducted to describe the Maxwell–Wagner (MW) relaxation effects. The work supports the importance of accounting for soil structural properties to understand and predict soil dielectric response and ultimately to find models that can describe the dielectric–water content relationship in fine-textured soils measured with sensors.
19
Gulidova, Valentina Andreevna, Vladimir Alexandrovich Kravchenko, and Vyacheslav Leonidovich Zakharov. "Optimization of The Soil Agrophysical Properties for Spring Rape on Leached Black Soil." Revista Amazonia Investiga 9, no. 29 (May 18, 2020): 63–68. http://dx.doi.org/10.34069/ai/2020.29.05.8.
Full textAbstract:
An important agronomic task in cultivating spring rape is improving the physical properties of leached black soil, which are extremely important for increasing its productivity. A central role in the physics of these soils is played by studying its density, which helps regulate the soil processes and maintain favorable conditions for spring rape. According to the studies, the highest productivity of spring rape is observed in the case of the arable layer density of 1.00 – 1.10 g/cm3. Moreover, in the case of soil density of 1.10 g/cm3, productivity is better by 5.6 – 8.5 % than in the case of 1.00 g/cm3. The number of seeds per pod has increased especially strongly (by 13.8 %). In the subsurface layer (30 – 40 cm), soil density of 1.10 – 1.20 g/cm3 is optimal for spring rape growth and development.
20
Bieganowski, Andrzej, Grzegorz Józefaciuk, Lidia Bandura, Łukasz Guz, Grzegorz Łagód, and Wojciech Franus. "Evaluation of Hydrocarbon Soil Pollution Using E-Nose." Sensors 18, no. 8 (July 30, 2018): 2463. http://dx.doi.org/10.3390/s18082463.
Full textAbstract:
The possibility of detecting low levels of soil pollution by petroleum fuel using an electronic nose (e-nose) was studied. An attempt to distinguish between pollution caused by petrol and diesel oil, and its relation to the time elapsed since the pollution event was simultaneously performed. Ten arable soils, belonging to various soil groups from the World Reference Base (WRB), were investigated. The measurements were performed on soils that were moistened to field capacity, polluted separately with both hydrocarbons, and then allowed to dry slowly over a period of 180 days. The volatile fingerprints differed throughout the course of the experiment, and, by its end, they were similar to those of the unpolluted soils. Principal component analysis (PCA) and artificial neural network (ANN) analysis showed that the e-nose results could be used to detect soil contamination and distinguish between pollutants and contamination levels.
21
Ranganai, Rubeni Tawanda, Moikwathai Moidaki, and James G. King. "Magnetic Susceptibility of Soils from Eastern Botswana: A Reconnaissance Survey and Potential Applications." Journal of Geography and Geology 7, no. 4 (December 2, 2015): 45. http://dx.doi.org/10.5539/jgg.v7n4p45.
Full textAbstract:
<p class="zhengwen">Soil magnetic properties measurements are relatively fast and inexpensive but have been proved to be sufficient for preliminary investigations in diverse socio-developmental issues. This paper presents results of a reconnaissance study of soil colour and magnetic susceptibility (c) in eastern Botswana, where ~80% of the population resides. The work is a first step to creating a database of rock and soil magnetic properties and to document spatial variations in magnetic properties in the country. These measurements are important as constraints for interpretation of available aeromagnetic data and can also be exploited for environmental soil research (pollution) and land-use planning (agriculture). The soils sampled include derivatives of varying types and provenance such as Archean gneissic granitoids, metamorphosed rocks (granulites), volcano-sedimentary assemblages, Karoo basalts, and alluvial sediments. A soil colour chart was used since soil colours and magnetic properties are diagnostic of its parent rock sources and weathering profiles. Soil magnetic susceptibilities were measured at both low frequency (0.46 MHz, clf) and high frequency (4.6 MHz, chf), thus allowing calculation of frequency-dependent susceptibility (cfd, cfd%) for detecting ultra-fine ferromagnetic minerals.</p>It was found that soils with Hues ranging from 7.5YR to 10YR have appreciable amount of magnetic materials and soils with Hues of 2.5YR are generally nonmagnetic. The results of soil magnetic susceptibility profiles show spatial variation closely related to the variation in basement rocks, which provides excellent evidence that the magnetic susceptibility variation reflects basement rocks or bedrock composition (soil parent material). In relation to the Botswana physiographic units, soils from the hardveld (Precambrian) show the highest susceptibilities, followed by those from the sandveld, with the lowest values being from the alluvial. The frequency dependent magnetic susceptibilities indicate the presence of ultra-fine super-paramagnetic minerals such as magnetite/maghemite. It is suggested that a systematic and continuous programme of rock and soil magnetic measurements would benefit various socio-economic and development priority sectors of Botswana. This also applies to many developing countries in Africa where soil physics and measurement of soil susceptibility in particular, is generally still at an embryonic stage.
22
Xosrov qızı Məcnunlu Musabəyli, Könül. "Status of land use in Mil-Aran Karabakh cadastral region." NATURE AND SCIENCE 11, no. 06 (August 23, 2021): 24–29. http://dx.doi.org/10.36719/2707-1146/11/24-29.
Full textAbstract:
Mil-Aran Karabakh cadastral region includes Barda, Agjabadi, Beylagan, Tartar regions as a whole, Aghdam, Aghdara region and Khojavend plain lands. Gray-meadow, meadow-forest, subasar alluvial meadow, gray, meadow-swamp, chestnut, meadow-chestnut soils are spread in the territory of this cadastral region. Grass-gray soils are transitional and are distributed in the strip between the gray-brown (chestnut) and meadow gray-brown (chestnut) soils of the dry steppes and the gray soils growing in drier conditions. Very large areas of the described lands are used for irrigated agriculture. The subasar regime of rivers and the resulting fresh alluvial sediments play a key role in the formation of subasar meadow-forest soils. During the autumn season, especially during floods, the rhythm of soil formation is repeatedly disrupted. This, of course, is reflected in the properties and morphological structure of these soils. Areas with gray soils have an arid semi-desert and dry steppe climate with an average annual temperature of 13.5-14.60. The temperature of the hot months is much higher. Unlike subasar meadow-forest lands of our republic, subasar-meadow soils are formed under meadows and shrubs. Rich grasses play an important role in enriching these soils with organic matter and ash elements. Meadow-swamp lands are spread in a relatively limited area of the republic. These soils are usually formed in the low and lowlands of the relief. The ecological and geographical features of the meadow-brown soils are in many respects similar to those of the brown soils. However, hydrothermal conditions are distinguished by the large seasonal differences, additional moisture due to surface and ground moisture. Our area is subject to varying degrees of salinization and erosion. We know that saline soils are lands with salts that are easily soluble in water in a 2-meter layer of soil. The effect of groundwater on soil salinization also depends on the degree of mineralization of that water. In this case, the crisis rate of groundwater mineralization is taken. Key words: Groundwater, mineralization rate,salt accumulation, irrigated soils, drainage rate
23
Ekici, A., S. Chadburn, N. Chaudhary, L. H. Hajdu, A. Marmy, S. Peng, J. Boike, et al. "Site-level model intercomparison of high latitude and high altitude soil thermal dynamics in tundra and barren landscapes." Cryosphere 9, no. 4 (July 22, 2015): 1343–61. http://dx.doi.org/10.5194/tc-9-1343-2015.
Full textAbstract:
Abstract. Modeling soil thermal dynamics at high latitudes and altitudes requires representations of physical processes such as snow insulation, soil freezing and thawing and subsurface conditions like soil water/ice content and soil texture. We have compared six different land models: JSBACH, ORCHIDEE, JULES, COUP, HYBRID8 and LPJ-GUESS, at four different sites with distinct cold region landscape types, to identify the importance of physical processes in capturing observed temperature dynamics in soils. The sites include alpine, high Arctic, wet polygonal tundra and non-permafrost Arctic, thus showing how a range of models can represent distinct soil temperature regimes. For all sites, snow insulation is of major importance for estimating topsoil conditions. However, soil physics is essential for the subsoil temperature dynamics and thus the active layer thicknesses. This analysis shows that land models need more realistic surface processes, such as detailed snow dynamics and moss cover with changing thickness and wetness, along with better representations of subsoil thermal dynamics.
24
Simansky, Vladimir, Jan Horak, Martin Juriga, and Dusan Srank. "Soil structure and soil organic matter in water-stable aggregates under different application rates of biochar." VIETNAM JOURNAL OF EARTH SCIENCES 40, no. 2 (June 1, 2018): 97–108. http://dx.doi.org/10.15625/0866-7187/40/2/11090.
Full textAbstract:
The effects of biochar and biochar combined with N-fertilizer on the content of soil organic matter in water-stable aggregates were investigated. A field experiment was conducted with different biochar application rates: B0 control (0 t ha-1), B10 (10 t ha-1) and B20 (20 t ha-1) and 0 (no N), 1st and 2nd levels of nitrogen fertilization on silt loam Haplic Luvisol (Dolna Malanta, Slovakia), in 2014. The N doses of level 1 were calculated on required average crop production using balance method. Level 2 included additional 100% of N in year 2014 and additional 50% of N in year 2016. The effects were investigated during the growing seasons of spring barley and spring wheat in 2014 and 2016, respectively. Results indicate that the B20N2 treatment significantly increased the proportion of water-stable macro-aggregates (WSAma) and reduced water-stable micro-aggregates (WSAmi). Aggregate stability increased only in the B20N1 treatment. The B20N2 treatment showed a robust decrease by 27% in the WSAma of 0.5-0.25 mm. On the other hand, an increase by 56% was observed in the content of WSAma with fractions 3-2 mm compared to the B0N0 treatment. The effect of N fertilizer on WSAma was confirmed only in the case of the B10N2 treatment. The proportion of WSAma with fractions 3-2 mm decreased by 42%, while the size fraction of 0.5-0.25 mm increased by 30% compared to the B10N0 treatment. The content of WSAma with fractions 1-0.5 mm decreased with time. On the contrary, the content of WSAma with particle sizes above 5 mm increased with time in all treatments except the B10N2 and B20N2 treatments. A statistically significant trend was identified in the proportion of WSA in the B10N2 and B20N2 treatments, which indicates that biochar with higher application levels of N fertilizer stabilizes the proportion of water-stable aggregates. In all treatments, the content of soil organic carbon (SOC) and labile carbon (CL) in WSAmi was lower than those in WSAma. A considerable decrease of SOC in the WSAma >5 mm and an increase of SOC in WSAmi were observed when biochar was applied at the rate of 10 t ha-1. Contents of SOC in WSAmi increased as a result of adding biochar combined with N fertilizer at first level. CL in WSA significantly increased in all size fractions of WSA.References Abiven S., Hund A., Martinsen V., Cornelissen G., 2015. Biochar amendment increases maize root surface areas and branching: a shovelomics study in Zambia. Plant Soil, 342, 1-11. Agegnehu G., Bass A.M., Nelson P.N., and Bird M.I., 2016. Benefits of biochar, compost and biochar–compost for soil quality, maize yield and greenhouse gas emissions in a tropical agricultural soil. Sci. Tot. Environ., 543, 295-306. Angers D.A., Samson N., Legere A., 1993. Early changes in water-stable aggregation induced by rotation and tillage in a soil under barley production. Can. J. Soil Sci., 73, 51-59. Atkinson Ch.J., Fitzgerald J.D., Hipps N.A., 2010. Potential mechanisms for achieving agricultural benefits from biochar application to temperate soils: a review. Plant Soil, 337, 1-18. Balashov E., Buchkina N., 2011. Impact of short- and long-term agricultural use of chernozem on its quality indicators. Int. Agrophys., 25, 1-5. Barrow C.J., 2012. Biochar: potential for countering land degradation and for improving agriculture. Appl. Geogr., 34, 21-28. Barthes B.G., Kouakoua E.T., Larre-Larrouy M.C., Razafimbelo T.M., De Luca E.F., Azontonde A., Neves C.S.V.J., De Freitas P.L., Feller C.L., 2008. Texture and sesquioxide effects on water-stable aggregates and organic matter in some tropical soils. Geoderma, 143, 14-25. Benbi D.K., Brar K., Toor A.S., Sharma S., 2015. Sensitivity of labile soil organic carbon pools to long-term fertilizer, straw and manure management in rice-wheat system. Pedosphere, 25, 534-545. Benbi D.K., Brar K., Toor A.S., Singh P., Singh H., 2012. Soil carbon pools under poplar-based agroforestry, rice-wheat, and maize-wheat cropping systems in semi-arid India. Nutr. Cycl. Agroecosys., 92, 107-118. Blanco-Canqui H., Lal L., 2004. Mechanisms of carbon sequestration in soil aggregates. Crit. Rev. Plant Sci., 23, 481-504. Brevik E.C., Cerda A., Mataix-Solera J., Pereg L., Quinton J.N., Six J., Van Oost K., 2015. The interdisciplinary nature of SOIL. SOIL, 1, 117-129. Brodowski S., John B., Flessa H., Amelung W., 2006. Aggregate-occluded black carbon in soil. Eur. J. Soil Sci., 57, 539-546. Bronick C.J., Lal R., 2005. The soil structure and land management: a review. Geoderma, 124, 3-22. Chenu C., Plante A., 2006. Clay-sized organo-mineral complexes in a cultivation chronosequece: revisiting the concept of the “primary organo-mineral complex”. Eur. J. Soil Sci., 56, 596-607. Dziadowiec H., Gonet S.S., 1999. Methodical guide-book for soil organic matter studies. Polish Society of Soil Science, Warszawa, 65p. Elliott E.T., 1986. Aggregate structure and carbon, nitrogen, and phosphorus in native and cultivated soils. Soil Sci. Soc. Am. J., 50, 627-633. Fischer D., Glaser B., 2012. Synergisms between compost and biochar for sustainable soil amelioration, In: Kumar S. (ed.): Management of Organic Waste, In Tech Europe, Rijeka, 167-198. Glaser B., Lehmann J., Zech W., 2002. Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal - a review. Biol. Fertil. Soils., 35, 219-230. Heitkotter J., and B. Marschner, 2015. Interactive effects of biochar ageing in soils related to feedstock, pyrolysis temperature, and historic charcoal production. Geoderma, 245-246, 56-64. Herath H.M.S.K., Camps-Arbestain M., Hedley M., 2013. Effect of biochar on soil physical properties in two contrasting soils: an Alfisol and an Andisol. Geoderma, 209-210, 188-197. Hillel D., 1982, Introduction to soil physics. Academic Press, San Diego, CA , 364 p. Chenu C., Plante A., 2006. Clay-sized organo-mineral complexes in a cultivation chronosequence: revisiting the concept of the “primary organo-mineral complex”. Eur. J. Soil Sci., 56, 596-607. IUSS Working Group WRB., 2014. World reference base for soil resources 2014. International soil classification system for naming soils and creating legends for soil maps. World Soil Resources Reports, 106, FAO, Rome., 112p. Jeffery S., Verheijen F.G.A., Van der Velde M., Bastos A.C., 2011. A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis. Agr. Ecosys. Environ., 144, 175-187. Jien S.H., Wang Ch.S., 2013. Effects of biochar on soil properties and erosion potential in a highly weathered soil. Catena, 110, 225-233. Kammann C., Linsel S., Goßling J., Koyro H.W., 2011. Influence of biochar on drought tolerance of Chenopodium quinoa Willd and on soil-plant relations. Plant Soil, 345, 195-210. Kodesova R., Nemecek K., Zigova A., Nikodem A., Fer M., 2015. Using dye tracer for visualizing roots I pact on soil structure and soil porous system. Biologia, 70, 1439-1443. Krol, A., Lipiec, J., Turski, M., J. Kuoe, 2013. Effects of organic and conventional management on physical properties of soil aggregates. Int. Agrophys., 27, 15-21. Kurakov A.V., Kharin S.A., 2012. The Formation of Water-Stable Coprolite Aggregates in Soddy-Podzolic Soils and the Participation of Fungi in This Process. Eur. Soil Sci., 45, 429-434. Loginow W., Wisniewski W., Gonet S.S., Ciescinska B., 1987. Fractionation of organic carbon based on susceptibility to oxidation. Pol. J. Soil Sci., 20, 47-52. Lynch, J.M., and E. Bragg, 1985. Microorganisms and soil aggregate stability. Adv. Soil Sci., 2, 133-171. MHYPERLINK "about:blank"unkholm L.J., Schjonning P., Debosz K., Jensen H.E., Christensen B.T., 2002. Aggregate strength and mechanical behaviour of a sandy loam soil under long-term fertilization treatments. Eur. J. Soil Sci., 53, 129-137. Paradelo R., Van Oort F., Chenu C., 2013. Water-dispersible clay in bare fallow soils after 80 years of continuous fertilizer addition. Geoderma, 200-201, 40-44. Purakayastha T.J., Kumari S., Pathak H., 2015. Characterisation, stability, and microbial effects of four biochars produced from crop residues. Geoderma, 239-240, 293-303. Rees F., Germain C., Sterckeman T., Morel J.L., 2015. Plant growth and metal uptake by a non-hyperaccumulating species (Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaea caerulescens) in contaminated soils amended with biochar. Plant Soil, 395, 57-73. Saha D., Kukal S.S., Sharma S., 2011. Land use impacts on SOC fractions and aggregate stability in typic Ustochrepts of Northwest India. Plant Soil, 339, 457-470. Six J., Bossuyt H., Degryze S., Denef K., 2004. A history of research on the link between (micro)aggregates, soil biota, and soil organic matter dynamics. Soil Till. Res., 79, 7-31. Six J., Elliott E.T., Paustian K., 2000. Soil macroaggregate turnover and microaggregate formation: A mechanism for C sequestration under no-tillage agriculture. Soil Biol. Biochem., 32, 2099-2103. Soinne H., Hovi J., Tammeorg P., Turtola E., 2014. Effect of biochar on phosphorus sorption and clay soil aggregate stability. Geoderma, 219-220, 162-167. Simansky V., 2013. Soil organic matter in water-stable aggregates under different soil management practices in a productive vineyard. Arch. Agron. Soil Sci., 59(9), 1207-1214. Simansky V., Jonczak J., 2016. Water-stable aggregates as a key element in the stabilization of soil organic matter in the Chernozems. Carp. J. Earth Environ. Sci., 11, 511-517. Simon T., Javurek M., Mikanova O., Vach M., 2009. The influence of tillage systems on soil organic matter and soil hydrophobicity. Soil Till, Res., 105, 44-48. Tiessen H., Stewart J.W.B., 1988. Light and electron microscopy of stainedmicroaggregates: the role of organic matter and microbes in soil aggregation. Biogeochemistry, 5, 312-322. Tisdall J.M., Oades J.M., 1980. The effect of crop rotation on aggregation in a red-brown earth. Austr. J. Soil Res., 18, 423-433. Vadjunina A.F., Korchagina Z.A., 1986. Methods of Study of Soil Physical Properties. Agropromizdat, Moscow, 415p. Vaezi A.R., Sadeghi S.H.R., Bahrami H.A., Mahdian M.H., 2008. Modeling the USLE K-factor for calcareous soils in northwestern Iran. Geomorphology, 97, 414-423. Von Lutzow M., Kogel-Knabner I., Ekschmitt K., Matzner E., Guggenberger G., Marschner B., Flessa H., 2006. Stabilization of organicmatter in temperate soils:mechanisms and their relevance under different soil conditions a review. Eur. J. Soil Sci., 57, 426-445.
25
Protasenya, О. N., L. V. Larchenkov, and M. L. Protasenya. "DEFORMATION MECHANISM OF STRUCTURAL BODY COMPRESSION." Science & Technique 17, no. 1 (February 9, 2018): 29–41. http://dx.doi.org/10.21122/2227-1031-2018-17-1-29-41.
Full textAbstract:
In order to prepare soil for sowing of agricultural crops it is necessary to have a number of engineering structures that ensure its qualitative treatment and protection from erosion. Modern equipment do not fully meet the whole complex of specified requirements. Application of tillage machinery being used for main soil cultivation is directed on suppression (destruction) of natural vegetation which is considered as the strongest competitor to cultivated plants. From the other side, vegetation on the Earth’s surface plays an important role for reliable protection of soil from erosion. Destruction of vegetation throughout the whole period of crop tending leads to the fact that the remaining cultivated plants are not able to protect soil from erosion by such natural aggressive factors as rain storms and strong winds. As a consequence, processes of soil structure destruction and losses of entire soil strata and its fertility occur in the geographical (landscape) envelope. Thus, equipment for primary and secondary soil tillage exerts double impact: from one side, killing of weeds takes place, and on the other hand, there is destruction (erosion) of soil structure and profiles of its geographical envelope. The soil, in the understanding of the earth, is the perfect place that gives life to plants and organisms, has a fertility. For the last 50 years analytical scope of physical processes occurring in the soil has been extended, physical methods for investigation of soil properties and application of technical equipment for assessment of physical-mechanical soil characteristics have got widespread use. However, there is no summative investigation on soil physics which includes and reveals thermodynamics, electrophysics and nuclear physics of soils. At the same time an integrated approach for studying such complicated object makes it possible to understand important nature of some processes occurring in the soil and to develop practical measures for fertility improvement and erosion reduction. The paper considers problems pertaining to deformation mechanism while forming soil structure and its compression under influence of external loadings: magnetic, electric, physico-chemical, gravitational and thermal fields and working organs of tillage tools.
26
Gorban, V. A. "Ecological soil physics as section of ecological soil science." Ecology and Noospherology 26, no. 3-4 (September 7, 2015): 96–105. http://dx.doi.org/10.15421/031523.
Full textAbstract:
Nowadays, there is a general penetration of ecology in other related sciences. Soil science is not an exception. To the evidence of this, the works of soil scientists may serve, that have appeared recently. It is shown that the ecology of soil is a broader area of the genetic soil science, than ecological soil science. In addition to the doctrine of the ecological functions of soil, modern soil ecology also includes the factor ecology and the doctrine of biosphere soil conservation. In modern soil science there are 2 main areas – fundamental, which aims to study all the features of soil as a natural body, and applied that examines various aspects of soil use by man. At the same time it should be noted that most of soil scientists until recently isolated a genetic soil science in two main areas – the genesis and the geography of soils. Academician L. I. Prasolov (1978) was the first who proposed to allocate soil ecology in a separate section of soil science, along with the above directions. V. R. Volobuev (1963) hold on to the similar views. I. A. Sokolov (1993) showed that the section «Soil ecology» is equal to such sections of soil science as the «Genesis of the soil» and «Geography of the soil». N. A. Gorin (2005) hold on to the similar point of view. On this basis, we offer the following vision of the place of soil ecology in the structure of modern soil science. This scheme is based on the allocation of basic research in the areas of soil science by the team of authors under the leadership of the Moscow State University V. A. Kovda and B. G. Rozanov (Pochvovedenie, 1988). The classification of the historic area of soil science is identified with the genesis of soil by us, and pedography – with the geography of soil. The scientific achievements of other fundamental areas (pedognostika, dynamic soil science, regional soil science, history and methodology of science) are widely used to address key issues of historical soil science and pedography. The structure of the direction «Ecology of soil» is developed by academician G. V. Dobrovolsky and E. D. Nikitin (2012). This doctrine of the ecological functions of soil, classification by B. F. Aparin (2012) is a fundamental direction, the theoretical basis of ecological soil science, related to the applied directions. After L. O. Karpachevsky (2005), who considers the ecological functions of soil subject as ecological soil science, we identify the ecological soil science with the doctrine of the ecological functions of soil in some extent. This view is confirmed by the definition of ecological soil science, formulated G. V. Dobrovolsky and G. S. Kust (2012) – «This is a direction in modern soil science, studied the role of soil as a unique habitat of plants, animals, microorganisms, and especially – in human life, in the functioning of the biosphere and the individual ecosystems». From the above definition, it is clear that in this case, the authors believe that the core of ecological soil science is ecological functions of soil, which manifest themselves through their specific role in nature and human life. The subject of the study of ecological soil science, as indicated by L. O. Karpachevsky (2005), is the ecological functions of soil. Modern physics of soil – is the area of soil science that studies the physical properties of the soil and the place in which physical processes are flowing (Voronin, 1986). As you can see from the definition, the ecological functions of soil caused by the physical properties of soil, remain outside the field of soil physics research. For this reason, there is a need for the provision and the development of ecological soil physics, which is based on theoretical and practical achievements of classical physics of soil, and will also pay close attention to research the ecological functions of soil.
27
Simangunsong, David, Satrio Wibowo, and Zufialdi Zakaria. "Bearing Capacity of very Expansive Soils at Jatinangor Area, West Java, Indonesia." MATEC Web of Conferences 147 (2018): 07003. http://dx.doi.org/10.1051/matecconf/201814707003.
Full textAbstract:
Expansive soil is a kind of soil that has ability to shrinkage and swelling. According to Ronny (2014) Jatinangor area has expansive soil that is so very influential in the planning of infrastructure construction. This research aimed to measure the bearing capacity of the very expansive soils in Jatinangor area and to determine the correlation between activity number of soil and its bearing capacity. The method used is to collect the soil physics and mechanics data. Based on the soil mechanics data, the research location is divided into three zones of allowable bearing capacity, those are zone with allowable bearing capacity < 4 T/m2, zone with allowable bearing capacity 4-7 T/m2, and zone with allowable bearing capacity > 7 T/m2. The correlation between activity number and bearing capacity of soil follows the equation qa = -1.9505(A) + 6.957 with correlation coefficient is -0.7911.
28
Kahaer, Yasenjiang, and Nigara Tashpolat. "Estimating Salt Concentrations Based on Optimized Spectral Indices in Soils with Regional Heterogeneity." Journal of Spectroscopy 2019 (September 9, 2019): 1–15. http://dx.doi.org/10.1155/2019/2402749.
Full textAbstract:
Soil salinity is one of the most damaging environmental problems worldwide, especially in arid and semiarid regions. The objectives of this study were to improve the inversion accuracy of soil salt content (SSC) in soils with spectral heterogeneity by using optimized spectral indices. Soil samples at a 0–20 cm depth were taken from Keriya Oasis (98 soil samples), Ugan-Kuqa Oasis (49 soil samples), and Ebinur Lake Basin (57 soil samples). SSC and spectral reflectance (SR) of all the 204 soil samples were determined. To comprehensively analyze the field-collected hyperspectral data, various band combinations were used to calculate a normalized difference spectral index (NDSI) and ratio spectral index (RSI). Then, the relationships between the indices and SSC were examined, and the most robust relationships were demonstrated. The partial least squares regression (PLSR) method was utilized to develop a predictive model of SSC, and the variable importance in the projection (VIP) method was used during modeling. The results revealed that (i) the salinized soils in different regions had apparent differences in both reflectance and spectral curve morphology, but the optimized spectral indices method effectively overcame the regional heterogeneity of salinized soil hyperspectral characteristics, and the correlation with SSC was always kind, with correlation coefficients up to 0.748 at 0.001 level of significance; (ii) the VIP filtering method effectively selected the optimal independent model, and the modeling accuracy was better than the single optimization index (R2Pre = 0.83 and RMSEPre = 2.31 g·kg−1) by using the combination of two optimal indices; (iii) although the global modeling accuracy was significantly lower than the local modeling accuracy due to the inconsistent salt sensitivity bands of salinized soils in different regions, combined with cross-validation analysis, the global model had the ability to predict soil salinization accurately (R2Pre = 0.69 and RMSEPre = 8.45 g·kg−1). The methods developed in this study can be applied in other arid and semiarid areas. Besides, the study also provides examples for aerospace hyperspectral remote sensing of cross-regional soil salinization.
29
Zhai, Yang, Li, Jiang, Ye, Li, Li, and Li. "Fuzzy Coordination Control Strategy and Thermohydraulic Dynamics Modeling of a Natural Gas Heating System for in Situ Soil Thermal Remediation." Entropy 21, no. 10 (October 5, 2019): 971. http://dx.doi.org/10.3390/e21100971.
Full textAbstract:
Soil contamination remains a global problem. Among the different kinds of remediation technologies, in situ soil thermal remediation has attracted great attention in the environmental field, representing a potential remedial alternative for contaminated soils. Soils need to be heated to a high temperature in thermal remediation, which requires a large amount of energy. For the natural gas heating system in thermal remediation, a fuzzy coordination control strategy and thermohydraulic dynamics model have been proposed in this paper. In order to demonstrate the superiority of the strategy, the other three traditional control strategies are introduced. Analysis of the temperature rise and energy consumption of soils under different control strategies were conducted. The results showed that the energy consumption of fuzzy coordination control strategy is reduced by 33.9% compared to that of the traditional control strategy I, constant natural gas flow and excess air ratio. Further, compared to the traditional control strategy II, constant excess air ratio and desired outlet temperature of wells, the strategy proposed can reduce energy consumption by 48.7%. The results illustrate the superiority of the fuzzy coordination control strategy, and the strategy can greatly reduce energy consumption, thereby reducing the cost of in situ soil thermal remediation.
30
MILLÁN, H., M. AGUILAR, J. DOMÌNGUEZ, L. CÈSPEDES, E. VELASCO, and M. GÒNZALEZ. "A NOTE ON THE PHYSICS OF SOIL WATER RETENTION THROUGH FRACTAL PARAMETERS." Fractals 14, no. 02 (June 2006): 143–48. http://dx.doi.org/10.1142/s0218348x06003131.
Full textAbstract:
Fractals are important for studying the physics of water transport in soils. Many authors have assumed a mass fractal structure while others consider a fractal surface approach. Each model needs comparisons on the same data set in terms of goodness-of-fit and physical interpretation of parameters. In this note, it is shown, with some representative data sets, that a pore-solid interface fractal model could fit soil water retention data better than a mass fractal model. In addition to the interfacial fractal dimension, this model predicts the tension at dryness. This value is very close to 106 kPa as theoretically predicted.
31
Zango, Muttaqa Uba, Khairul Anuar Kassim, Abubakar Sadiq Muhammed, Kamarudin Ahmad, and Jodin Makinda. "Desiccation Induced Shrinkage of Compacted Lateritic Soil Treated via Enzymatic Induced Calcium Carbonate Precipitation Technique." Materials Science Forum 1030 (May 2021): 110–23. http://dx.doi.org/10.4028/www.scientific.net/msf.1030.110.
Full textAbstract:
Exploring the biological process to enhance the engineering properties of soil have received enormous recognition in recent years. Enzymatic induced calcium carbonate precipitation (EICP) is one of the bio-inspired methods of utilizing free urease to precipitates calcite from urea and calcium ions for bettering the geotechnical properties of poor soils. In this research, the EICP technique was used to improve the volumetric shrinkage strain of compacted soil liner. In this work, the residual soil was treated with various concentrations of cementations ranging from 0.25 to 1.0 M, and the soil was subjected to Atterberg limit tests, compaction test using British standard light (BSL) and reduced British standard light (RBSL) and desiccation drying volumetric shrinkage strain test. The study's findings revealed a remarkable improvement in the liquid limit and plasticity index of the treated residual soils compared to natural soil. It was also found that the volumetric shrinkage strain of the treated soil reduces progressively from 5.24% of natural to 1.49% at 1.0 M cementation solution when the soils were prepared at 0% OMC and BSL compaction effort. Based on the consideration of permissible VSS of less than 4%, the best treatment was obtained at 1.0 M for both BSL and RBSL prepared samples. Similarly, the best compaction plane is found in the treated with 1.0 M cementation solution.
32
Jabro, J. D., W. B. Stevens, W. M. Iversen, B. L. Allen, and U. M. Sainju. "Irrigation Scheduling Based on Wireless Sensors Output and Soil-Water Characteristic Curve in Two Soils." Sensors 20, no. 5 (February 29, 2020): 1336. http://dx.doi.org/10.3390/s20051336.
Full textAbstract:
Data-driven irrigation planning can optimize crop yield and reduce adverse impacts on surface and ground water quality. We evaluated an irrigation scheduling strategy based on soil matric potentials recorded by wireless Watermark (WM) sensors installed in sandy loam and clay loam soils and soil-water characteristic curve data. Five wireless WM nodes (IRROmesh) were installed at each location, where each node consisted of three WM sensors that were installed at 15, 30, and 60 cm depths in the crop rows. Soil moisture contents, at field capacity and permanent wilting points, were determined from soil-water characteristic curves and were approximately 23% and 11% for a sandy loam, and 35% and 17% for a clay loam, respectively. The field capacity level which occurs shortly after an irrigation event was considered the upper point of soil moisture content, and the lower point was the maximum soil water depletion level at 50% of plant available water capacity in the root zone, depending on crop type, root depth, growth stage and soil type. The lower thresholds of soil moisture content to trigger an irrigation event were 17% and 26% in the sandy loam and clay loam soils, respectively. The corresponding soil water potential readings from the WM sensors to initiate irrigation events were approximately 60 kPa and 105 kPa for sandy loam, and clay loam soils, respectively. Watermark sensors can be successfully used for irrigation scheduling by simply setting two levels of moisture content using soil-water characteristic curve data. Further, the wireless system can help farmers and irrigators monitor real-time moisture content in the soil root zone of their crops and determine irrigation scheduling remotely without time consuming, manual data logging and frequent visits to the field.
33
Nagare, R. M., P. Bhattacharya, J. Khanna, and R. A. Schincariol. "Coupled cellular automata for frozen soil processes." SOIL 1, no. 1 (January 14, 2015): 103–16. http://dx.doi.org/10.5194/soil-1-103-2015.
Full textAbstract:
Abstract. Heat and water movement in variably saturated freezing soils is a strongly coupled phenomenon. The coupling is a result of the effects of sub-zero temperature on soil water potential, heat carried by water moving under pressure gradients, and dependency of soil thermal and hydraulic properties on soil water content. This study presents a one-dimensional cellular automata (direct solving) model to simulate coupled heat and water transport with phase change in variably saturated soils. The model is based on first-order mass and energy conservation principles. The water and energy fluxes are calculated using first-order empirical forms of Buckingham–Darcy's law and Fourier's heat law respectively. The liquid–ice phase change is handled by integrating along an experimentally determined soil freezing curve (unfrozen water content and temperature relationship) obviating the use of the apparent heat capacity term. This approach highlights a further subtle form of coupling in which heat carried by water perturbs the water content–temperature equilibrium and exchange energy flux is used to maintain the equilibrium rather than affect the temperature change. The model is successfully tested against analytical and experimental solutions. Setting up a highly non-linear coupled soil physics problem with a physically based approach provides intuitive insights into an otherwise complex phenomenon.
34
Marchiori, Leonardo, André Studart, António Albuquerque, Victor Cavaleiro, and Abílio P. Silva. "Geotechnical Characterization of Water Treatment Sludge for Liner Material Production and Soft Soil Reinforcement." Materials Science Forum 1046 (September 22, 2021): 83–88. http://dx.doi.org/10.4028/www.scientific.net/msf.1046.83.
Full textAbstract:
A water treatment sludge (WTS) was characterized in order to evaluate if its properties would be suitable for use as liner of earthworks or for strengthening a clay soil. A WTS and a clayey soil was characterized in terms of granulometry, cumulative volumes, specific surface, density, plastic limit, liquid limit, water content, hydraulic conductivity, and characteristics of compaction (optimal water content and dry density). This study aimed to exhibit and evaluate these investigated parameters of WTS, soft soil and mixed proportions between the materials for liners’ material production while evaluating soft soils’ reinforcement feasibility. The results have shown WTS’s contribution with its fine granulometry and compaction characteristics, indicating filling properties and possible feasibility as soft soils additions for liners’ material production while being applicable for soils‘ reinforcements, corroborating with existing literature on the subject. Thus, the currently developed investigation has exposed WTS as a potential addition for these applications while also attending society’s new demands towards a more sustainable future.
35
KISHNÉ, A. SZ, C. L. S. MORGAN, H. C. CHANG, and L. B. KISH. "VIBRATION-INDUCED CONDUCTIVITY FLUCTUATION MEASUREMENT FOR SOIL BULK DENSITY ANALYSIS." Fluctuation and Noise Letters 07, no. 04 (December 2007): L473—L481. http://dx.doi.org/10.1142/s0219477507004112.
Full textAbstract:
Soil bulk density is a physical property of soils that affects water storage, water and nutrient movement, and plant root activity in the soil profile. The ability to quantify soil bulk density using vibration-induced conductivity fluctuation was investigated with possible field applications in the future. The AC electrical conductance of soil was measured using a pair of blade-like electrodes while exposing to periodic vibration. The blades were positioned longitudinally and transversally to the direction of the induced vibration to enable the calculation of a normalized index. This normalized index was expected to provide data independent from the vibration strength, and to reduce the effect of soil salinity and water content. Simulations on a simplified resistor lattice indicate that the ratio of transversal and longitudinal fluctuation decreases as soil bulk density increases. The experiment was conducted on natural and salinized fine sand at two moisture conditions and four compaction levels. The blade-shaped electrodes improved electrode-soil contact compared to cylindrical electrodes, and thereby, reduced measurement noise. Dry sand measurements showed an inverse correlation between the normalized conductivity fluctuation and soil bulk density for both longitudinal and transversal fluctuation. The wet natural and salinized soils performed very similarly as hypothesized, but their normalized VICOF response was not associated with bulk density changes. This lack of sensitivity might be attributed to the heavy electrodes and/or the specific vibration method used. The effects of electrode material, vibration method and soil properties on the experiment need further study.
36
Shang, Min, Qiang Xu, Shu Cai Li, and Lan Xin Zhang. "Research on Engineering Geology Properties of Residual Diorite in Jinan, Shandong Province, China." Advanced Materials Research 594-597 (November 2012): 434–38. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.434.
Full textAbstract:
Residual soils are weathering products of rocks that are commonly found under unsaturated conditions. Residual soil is one of special soils, and its engineering geology property is usually different because of the difference of resource rock type, the geology environment and weathering condition. By the means of analysis of the data attained by the methods of field exploration, laboratory test and testing in-situ, the physical and mechanical properties of the residual diorite in Jinan were studied deeply. It is proved that the stratigraphic section of the soil can be classified as two layers on the perpendicular direction. Considering the inhomogeneity of the residual soil mass and the widely divergence of the value of mechanics properties, the suggestion value of c, Φ , a, Es, fak were put forward for further guiding the engineering practice , on the base of physics and mechanics properties tests and the region practice experience. At the same time, it is pointed out that, at that region, the interlayer and inhomogeneity of the weathering layers should be emphasized in the process of projecting and constructing when the residual diorite acts as the foundation of the construction or one of the geologic layers.
37
Daly, K. R., S. D. Keyes, and T. Roose. "Determination of macro-scale soil properties from pore scale structures: image-based modelling of poroelastic structures." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, no. 2215 (July 2018): 20170745. http://dx.doi.org/10.1098/rspa.2017.0745.
Full textAbstract:
We show how a combination of X-ray computed tomography (X-CT) and image-based modelling can be used to calculate the effect of moisture content and compaction on the macroscopic structural properties of soil. Our method is based on the equations derived in Daly & Roose (2018 Proc. R. Soc. A 474 , 20170141. ( doi:10.1098/rspa.2017.0141 )), which we have extended so they can be directly applied to the segmented images obtained from X-CT. We assume that the soils are composed of air-filled pore space, solid mineral grains and a mixed phase composed of both clay particles and water. We considered three different initial soil treatments, composed of two different compaction levels and two different moisture contents. We found that the effective properties of the soils were unaffected by compaction over the range tested in this paper. However, changing the moisture content significantly altered the hydraulic and mechanical properties of the soils. A key strength of this method is that it enables the optimization or even design of soils composed from different constituents, with specific mechanical and hydraulic properties.
38
Bull, D. J., J. A. Smethurst, I. Sinclair, F. Pierron, T. Roose, W. Powrie, and A. G. Bengough. "Mechanisms of root reinforcement in soils: an experimental methodology using four-dimensional X-ray computed tomography and digital volume correlation." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2237 (May 2020): 20190838. http://dx.doi.org/10.1098/rspa.2019.0838.
Full textAbstract:
Vegetation on railway or highway slopes can improve slope stability through the generation of soil pore water suctions by plant transpiration and mechanical soil reinforcement by the roots. To incorporate the enhanced shearing resistance and stiffness of root-reinforced soils in stability calculations, it is necessary to understand and quantify its effectiveness. This requires integrated and sophisticated experimental and multi-scale modelling approaches to develop an understanding of the processes at different length scales, from individual root–soil interaction through to full soil-profile or slope scale. One of the challenges with multi-scale models is ensuring that they sufficiently closely represent real behaviour. This requires calibration against detailed high-quality and data-rich experiments. This study presents a novel experimental methodology, which combines in situ direct shear loading of a willow root-reinforced soil with X-ray computed tomography to capture the three-dimensional chronology of soil and root deformation within the shear zone. Digital volume correlation (DVC) analysis was applied to the computed tomography dataset to obtain full-field three-dimensional displacement and strain information. This paper demonstrates the feasibility and discusses the challenges associated with DVC experiments on root-reinforced soils.
39
Thabeng, Olaotse Lokwalo, Elhadi Adam, and Stefania Merlo. "Spectral Discrimination of Archaeological Sites Previously Occupied by Farming Communities Using In Situ Hyperspectral Data." Journal of Spectroscopy 2019 (October 17, 2019): 1–21. http://dx.doi.org/10.1155/2019/5158465.
Full textAbstract:
This study investigates the ability of field spectra measurements to discriminate between soils from non-sites (natural soils) and from archaeological sites, such as middens (rubbish-dumping areas) and animal byres. First, we tested whether there is a difference in the concentration of elements between different soil types using analysis of variance while random forest (RF) and forward variable selection (FVS) methods were used to select important soil elements for the classification of the archaeological sites. In the second approach, we evaluated the ability of field spectroscopy reflectance measurements to discriminate among nonsites, middens, vitrified dung, and nonvitrified dung byres. The guided regularised random forest (GRRF) was used to identify important wavelengths for the discrimination of abovementioned archaeological and nonarchaeological soils. Thereafter, the selected soil elements and wavelengths were used as input variables in the RF classification algorithm to classify the nonsites, middens, vitrified dung, and nonvitrified dung. The findings reveal that there is a significant difference in the composition of chemical elements and spectral signatures of nonsites, middens, vitrified dung, and nonvitrified dung. In summary, high classification accuracies achieved when using field spectroscopy data prove that remote sensing techniques can be used to exploit the spectral differences among the abovementioned soil types in mapping archaeological feature characteristics of farming communities’ settlements.
40
Capparelli, Giovanna, Gennaro Spolverino, and Roberto Greco. "Experimental Determination of TDR Calibration Relationship for Pyroclastic Ashes of Campania (Italy)." Sensors 18, no. 11 (November 1, 2018): 3727. http://dx.doi.org/10.3390/s18113727.
Full textAbstract:
Time domain reflectometry (TDR) is one of the most widely used techniques for indirect determination of soil volumetric water content (θ). TDR measures the relative dielectric constant (εr) which, in a three-phase system like the soil, depends on water, air, and solid matrix dielectric constants. Since dielectric constant of water is much larger than the other two, εr of bulk soil mainly depends on water content. In many cases, the application of TDR requires a specific calibration of the relationship θ(εr) to get quantitatively accurate estimates of soil water content. In fact, the relationship θ(εr) is influenced by various soil properties, such as clay content, organic matter content, bulk density, and aggregation. Numerous studies have shown that pyroclastic soils often exhibit a peculiar dielectric behavior. In Campania (Southern Italy) wide mountainous areas are covered by layered pyroclastic deposits of ashes (loamy sands) and pumices (sandy gravels), often involved in the triggering of landslides induced by rainwater infiltration. Reliable field measurements of water content of such soils are therefore important for the assessment of landslide risk. Hence, in this paper, the θ(εr) relationship has been experimentally determined on samples of typical pyroclastic soil of Campania, collected around Sarno, reconstituted with different porosities. The aim of the study is to identify specific calibration relationships for such soils based not only on empirical approaches. In this respect, a three-phase dielectric mixing model with a variable exponent is introduced, and the variable value of the exponent is related to the different dielectric properties of bond and free water within the soil pores.
41
Al-Ghamdi, Hanan. "Determination of the Activity Concentrations of Radium Isotopes in Soils of Some Farms in the Saudi Eastern Province and Estimation of Radiation Dose." Journal of Computational and Theoretical Nanoscience 15, no. 2 (February 1, 2018): 736–38. http://dx.doi.org/10.1166/jctn.2018.7153.
Full textAbstract:
In this study, Surveillance monitoring in nine farms at the eastern province in Saudi Arabia has been carried out to assess the radiological hazards from radium isotopes in soil. The 226Ra and 228Ra were measured by high purity germanium detector after been extracted from large volume irrigation water samples using strong cation exchange resin. The activity concentrations of 226Ra and 228Ra in the surface soil samples were measured by gamma spectrometry and their mean activities were 17.2 and 11.3 Bq/kg dry weight respectively. Good correlation was found between the radium content in soils and the sand component of the soil, and also between the combined radium isotopes (226Ra and 228Ra) in the irrigation water and soil. The absorbed dose rate from external gamma radiation due to the combined radium in soils and the corresponding annual effective dose were estimated and found to be lower than the corresponding world average values. On the basis of the current results, we may conclude that the presence of such activity of the combined radium isotopes in the soils of the investigated farms may not pose any radiological hazards to the public.
42
CHE, AILAN, XIANQI LUO, JINGHUA QI, and DEYONG WANG. "STUDY ON CORRELATION BETWEEN SHEAR WAVE VELOCITY AND GROUND PROPERTIES FOR GROUND LIQUEFACTION INVESTIGATION OF SILTS." International Journal of Modern Physics B 22, no. 31n32 (December 30, 2008): 5705–10. http://dx.doi.org/10.1142/s0217979208051042.
Full textAbstract:
Shear wave velocity (V s ) of soil is one of the key parameters used in assessment of liquefaction potential of saturated soils in the base with leveled ground surface; determination of shear module of soils used in seismic response analyses. Such parameter can be experimentally obtained from laboratory soil tests and field measurements. Statistical relation of shear wave velocity with soil properties based on the surface wave survey investigation, and resonant column triaxial tests, which are taken from more than 14 sites within the depth of 10 m under ground surface, is obtained in Tianjin (China) area. The relationship between shear wave velocity and the standard penetration test N value (SPT-N value) of silt and clay in the quaternary formation are summarized. It is an important problem to research the effect of shear wave velocity on liquefaction resistance of saturated silts (sandy loams) for evaluating liquefaction resistance. According the results of cyclic triaxial tests, a correlation between liquefaction resistance and shear wave velocity is presented. The results are useful for ground liquefaction investigation and the evaluation of liquefaction resistance.
43
Pachepsky, Ya, K. Rajkai, and B. Tóth. "Pedotransfer in soil physics: trends and outlook — A review —." Agrokémia és talajtan 64, no. 2 (December 2015): 339–60. http://dx.doi.org/10.1556/0088.2015.64.2.3.
Full textAbstract:
Parameters governing the retention and movement of water and chemicals in soils are notorious for the difficulties and high labor costs involved in measuring them. Often, there is a need to resort to estimating these parameters from other, more readily available data, using pedotransfer relationships. This work is a mini-review that focuses on trends in pedotransfer development across the World, and considers trends regarding data that are in demand, data we have, and methods to build pedotransfer relationships. Recent hot topics are addressed, including estimating the spatial variability of water contents and soil hydraulic properties, which is needed in sensitivity analysis, evaluation of the model performance, multimodel simulations, data assimilation from soil sensor networks and upscaling using Monte Carlo simulations. Ensembles of pedotransfer functions and temporal stability derived from “big data” as a source of soil parameter variability are also described. Estimating parameter correlation is advocated as the pathway to the improvement of synthetic datasets. Upscaling of pedotransfer relationships is demonstrated for saturated hydraulic conductivity. Pedotransfer at coarse scales requires a different type of input variables as compared with fine scales. Accuracy, reliability, and utility have to be estimated independently. Persistent knowledge gaps in pedotransfer development are outlined, which are related to regional soil degradation, seasonal changes in pedotransfer inputs and outputs, spatial correlations in soil hydraulic properties, and overland flow parameter estimation. Pedotransfer research is an integral part of addressing grand challenges of the twenty-first century, including carbon stock assessments and forecasts, climate change and related hydrological weather extreme event predictions, and deciphering and managing ecosystem services. Overall, pedotransfer functions currently serve as an essential instrument in the science-based toolbox for diagnostics, monitoring, predictions, and management of the changing Earth and soil as a life-supporting Earth system.
44
Jong van Lier, Quirijn de. "Revisiting the S-index for soil physical quality and its use in Brazil." Revista Brasileira de Ciência do Solo 38, no. 1 (February 2014): 1–10. http://dx.doi.org/10.1590/s0100-06832014000100001.
Full textAbstract:
The S-index was introduced in 2004 in a publication by A.R. Dexter. S was proposed as an indicator of soil physical quality. A critical value delimiting soils with rich and poor physical quality was proposed. At present, Brazil is world leader in citations of Dexter's publication. In this publication the S-theory is mathematically revisited and extended. It is shown that S is mathematically correlated to bulk density and total porosity. As an absolute indicator, the value of S alone has proven to be incapable of predicting soil physical quality. The critical value does not always hold under boundary conditions described in the literature. This is to be expected because S is a static parameter, therefore implicitly unable to describe dynamic processes. As a relative indicator of soil physical quality, the S-index has no additional value over bulk density or total porosity. Therefore, in the opinion of the author, the fact that bulk density or total porosity are much more easily determined than the water retention curve for obtaining S disqualifies S as an advantageous indicator of relative soil physical quality. Among the several equations available for the fitting of water retention curves, the Groenevelt-Grant equation is preferable for use with S since one of its parameters and S are linearly correlated. Since efforts in soil physics research have the purpose of describing dynamic processes, it is the author's opinion that these efforts should shift towards mechanistic soil physics as opposed to the search for empirical correlations like S which, at present, represents far more than its reasonable share of soil physics in Brazil.
45
Matua, Vakhtang, and Sergey Karpenko. "Influence of the Stabilizing Additive "ANT" and Soil Stabilizers «LSCS» and «PSCS» for the Strength Characteristics of Highly Dispersed Soils." Materials Science Forum 1043 (August 18, 2021): 121–25. http://dx.doi.org/10.4028/www.scientific.net/msf.1043.121.
Full textAbstract:
The article deals with the use of local highly dispersed unsuitable soils for the construction of foundations and pavements instead of imported expensive conditioned stone materials. A variant of solving this problem is proposed by strengthening weak (subsiding) soils with modern stabilizing additives and soil stabilizers.
46
WANG, CHING-JONG. "SIMULATION OF COLLISION CONTACTS AMONG DISJOINED SOIL-STRUCTURE BODIES UNDER SEISMIC MOTIONS." International Journal of Modern Physics B 22, no. 09n11 (April 30, 2008): 1544–51. http://dx.doi.org/10.1142/s0217979208047055.
Full textAbstract:
Structure bodies and surrounding soils in certain types of bridges and tunnels may be prone to collisions during earthquake. A dynamic system composed of discrete and finite elements is developed using explicit formulation for equations of motion, and nonlinearities in soils and at interfaces of disjoined regions are implemented. Time history solutions are carried out to examine the plastic deformation in soils as well as the integrity of structures. Two case studies are presented in which collisions among disjoined regions are anticipated in the event of extremely large earthquakes. Case one is based on a replica from a quake-stricken bridge, to illustrate that a backfill with moderate soil strength may be used as an energy-dissipating buffer to contain the shaken loose decks. The other case involves an underground subway station box with slurry walls alongside, to exemplify the seismic resistance of the dual-wall system.
47
Fang, Qian, Hanlie Hong, Lulu Zhao, Stephanie Kukolich, Ke Yin, and Chaowen Wang. "Visible and Near-Infrared Reflectance Spectroscopy for Investigating Soil Mineralogy: A Review." Journal of Spectroscopy 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/3168974.
Full textAbstract:
Clay minerals are the most reactive and important inorganic components in soils, but soil mineralogy classifies as a minor topic in soil sciences. Revisiting soil mineralogy has been gradually required. Clay minerals in soils are more complex and less well crystallized than those in sedimentary rocks, and thus, they display more complicated X-ray diffraction (XRD) patterns. Traditional characterization methods such as XRD are usually expensive and time-consuming, and they are therefore inappropriate for large datasets, whereas visible and near-infrared reflectance spectroscopy (VNIR) is a quick, cost-efficient, and nondestructive technique for analyzing soil mineralogic properties of large datasets. The main objectives of this review are to bring readers up to date with information and understanding of VNIR as it relates to soil mineralogy and attracts more attention from a wide variety of readers to revisit soil mineralogy. We begin our review with a description of fundamentals of VNIR. We then review common methods to process soil VNIR spectra and summary spectral features of soil minerals with particular attention to those <2 μm fractions. We further critically review applications of chemometric methods and related model building in spectroscopic soil mineral studies. We then compare spectral measurement with multivariate calibration methods, and we suggest that they both produce excellent results depending on the situation. Finally, we suggest a few avenues of future research, including the development of theoretical calibrations of VNIR more suitable for various soil samples worldwide, better elucidation of clay mineral-soil organic carbon (SOC) interactions, and building the concept of integrated soil mapping through combined information (e.g., mineral composition, soil organic matter-SOM, SOC, pH, and moisture).
48
Nazarious, Miracle Israel, María-Paz Zorzano, and Javier Martín-Torres. "Metabolt: An In-Situ Instrument to Characterize the Metabolic Activity of Microbial Soil Ecosystems Using Electrochemical and Gaseous Signatures." Sensors 20, no. 16 (August 11, 2020): 4479. http://dx.doi.org/10.3390/s20164479.
Full textAbstract:
Metabolt is a portable soil incubator to characterize the metabolic activity of microbial ecosystems in soils. It measures the electrical conductivity, the redox potential, and the concentration of certain metabolism-related gases in the headspace just above a given sample of regolith. In its current design, the overall weight of Metabolt, including the soils (250 g), is 1.9 kg with a maximum power consumption of 1.5 W. Metabolt has been designed to monitor the activity of the soil microbiome for Earth and space applications. In particular, it can be used to monitor the health of soils, the atmospheric-regolith fixation, and release of gaseous species such as N2, H2O, CO2, O2, N2O, NH3, etc., that affect the Earth climate and atmospheric chemistry. It may be used to detect and monitor life signatures in soils, treated or untreated, as well as in controlled environments like greenhouse facilities in space, laboratory research environments like anaerobic chambers, or simulating facilities with different atmospheres and pressures. To illustrate its operation, we tested the instrument with sub-arctic soil samples at Earth environmental conditions under three different conditions: (i) no treatment (unperturbed); (ii) sterilized soil: after heating at 125 °C for 35.4 h (thermal stress); (iii) stressed soil: after adding 25% CaCl2 brine (osmotic stress); with and without addition of 0.5% glucose solution (for control). All the samples showed some distinguishable metabolic response, however there was a time delay on its appearance which depends on the treatment applied to the samples: 80 h for thermal stress without glucose, 59 h with glucose; 36 h for osmotic stress with glucose and no significant reactivation in the pure water case. This instrument shows that, over time, there is a clear observable footprint of the electrochemical signatures in the redox profile which is complementary to the gaseous footprint of the metabolic activity through respiration.
49
Koven, C. D., E. A. G. Schuur, C. Schädel, T. J. Bohn, E. J. Burke, G. Chen, X. Chen, et al. "A simplified, data-constrained approach to estimate the permafrost carbon–climate feedback." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2054 (November 13, 2015): 20140423. http://dx.doi.org/10.1098/rsta.2014.0423.
Full textAbstract:
We present an approach to estimate the feedback from large-scale thawing of permafrost soils using a simplified, data-constrained model that combines three elements: soil carbon (C) maps and profiles to identify the distribution and type of C in permafrost soils; incubation experiments to quantify the rates of C lost after thaw; and models of soil thermal dynamics in response to climate warming. We call the approach the Permafrost Carbon Network Incubation–Panarctic Thermal scaling approach (PInc-PanTher). The approach assumes that C stocks do not decompose at all when frozen, but once thawed follow set decomposition trajectories as a function of soil temperature. The trajectories are determined according to a three-pool decomposition model fitted to incubation data using parameters specific to soil horizon types. We calculate litterfall C inputs required to maintain steady-state C balance for the current climate, and hold those inputs constant. Soil temperatures are taken from the soil thermal modules of ecosystem model simulations forced by a common set of future climate change anomalies under two warming scenarios over the period 2010 to 2100. Under a medium warming scenario (RCP4.5), the approach projects permafrost soil C losses of 12.2–33.4 Pg C; under a high warming scenario (RCP8.5), the approach projects C losses of 27.9–112.6 Pg C. Projected C losses are roughly linearly proportional to global temperature changes across the two scenarios. These results indicate a global sensitivity of frozen soil C to climate change ( γ sensitivity) of −14 to −19 Pg C °C −1 on a 100 year time scale. For CH 4 emissions, our approach assumes a fixed saturated area and that increases in CH 4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH 4 emission increases of 7% and 35% for the RCP4.5 and RCP8.5 scenarios, respectively, which add an additional greenhouse gas forcing of approximately 10–18%. The simplified approach presented here neglects many important processes that may amplify or mitigate C release from permafrost soils, but serves as a data-constrained estimate on the forced, large-scale permafrost C response to warming.
50
IL'ICHEV, ANDREJ T., GEORGE G. TSYPKIN, DAVID PRITCHARD, and CHRIS N. RICHARDSON. "Instability of the salinity profile during the evaporation of saline groundwater." Journal of Fluid Mechanics 614 (October 16, 2008): 87–104. http://dx.doi.org/10.1017/s0022112008003182.
Full textAbstract:
In this paper we investigate salt transport during the evaporation and upflow of saline groundwater. We describe a model in which a sharp evaporation–precipitation front separates regions of soil saturated with an air–vapour mixture and with saline water. We then consider two idealized problems. We first investigate equilibrium configurations of the freshwater system when the depth of the soil layer is finite, obtaining results for the location of the front and the upflow of water induced by the evaporation. We then develop a solution for a propagating front in a soil layer of infinite depth and investigate the gravitational stability of the salinity profile which develops below the front, obtaining marginal linear stability conditions in terms of a Rayleigh number and a dimensionless salt saturation parameter. Applying our findings to realistic parameter regimes, we predict that salt fingering is unlikely to occur in low-permeability soils, but is likely in high-permeability (sandy) soils under conditions of relatively low evaporative upflow.