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Academic literature on the topic 'Soils Soil structure'

Author: Grafiati

Published: 4 June 2021

Last updated: 27 January 2023

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Journal articles on the topic "Soils Soil structure"

Rengasamy, P., and KA Olsson. "Sodicity and soil structure." Soil Research 29, no. 6 (1991): 935. http://dx.doi.org/10.1071/sr9910935.

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Sodic soils are widespread in Australia reflecting the predominance of sodium chloride in groundwaters and soil solutions. Sodic soils are subject to severe structural degradation and restrict plant performance through poor soil-water and soil-air relations. Sodicity is shown to be a latent problem in saline-sodic soils where deleterious effects are evident only after leaching profiles free of salts. A classification of sodic soils based on sodium adsorption ratio, pH and electrolyte conductivity is outlined. Current understanding of the processes and the component mechanisms of sodic soil behaviour are integrated to form the necessary bases for practical solutions in the long term and to define areas for research. The principles of organic and biological amelioration of sodicity, as alternatives to costly inorganic amendments, are discussed.

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Aliboeva, M. A. "Morphological Structure Of Mountain Soils." American Journal of Agriculture and Biomedical Engineering 03, no. 12 (December 30, 2021): 33–37. http://dx.doi.org/10.37547/tajabe/volume03issue12-08.

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This article discusses morphological structure of mountain soils. The mountainous regions of the Republic of Uzbekistan are located mainly in Tashkent, Surkhandarya, Samarkand, Jizzakh, Syrdarya, Fergana Valley and Navoi regions, and differ from each other in their greenery, charm and structure. Mountain soils are distributed sequentially according to the law of vertical zoning, depending on the altitude above sea level. The soil cover in these regions is characterized by their development (evolution), genesis, agrochemical, agrophysical properties and, most importantly, morphological structure. Each region has its own natural factors, which directly affect the development and morphological structure of the soil cover.

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JavidSharifi, Behtash, and Sedigheh Gheisari. "EFFECTS OF STRUCTURE HEIGHT ON SEISMIC DEMAND OF MOMENT-RESISTING REINFORCED CONCRETE FRAMES CONSIDERING SOIL-STRUCTURE INTERACTION." NED University Journal of Research XVIII, no. 1 (January 1, 2021): 15–32. http://dx.doi.org/10.35453/nedjr-stmech-2020-0006.

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Forces and displacements induced in a building due to structural responses to earthquake excitation are called seismic demands which depend upon the input motion, structural characteristics, site effects and the interaction of structure with soil. Structural response of three laterally non-controlled moment-resisting reinforced concrete frame structures with three different soil conditions are have been investigated in this paper. The soil conditions include loose soil, medium soil and rigid ground. The soil-structure interaction of low-, mid- and high-rise frame structures with the above mentioned soil types was analysed by performing nonlinear response history analyses. A set of eleven earthquake motions was employed in the analyses and maximum structural seismic demands for the frame structures were calculated. It was found that pressure-independent relatively loose sandy soils are not very critical for low-rise structures. On the other hand, pressure-independent relatively loose sandy soils and pressure-independent medium sandy soils are highly critical for mid-rise and high-rise structures, respectively. Categorisation of the soils is performed based on the value ranges of a series of constitutive parameters. Further, fixity of the base is most effective in controlling storey displacements until approximately one-third of the structure height. Medium soil leads to highest maximum base shears in low-rise structures while fixed-base and medium cases, and fixed base state control the behaviours of mid-rise and high-rise structures, respectively.

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Zhai, Zhanghui, Yaguo Zhang, Shuxiong Xiao, and Tonglu Li. "Undrained Elastoplastic Solution for Cylindrical Cavity Expansion in Structured Cam Clay Soil Considering the Destructuration Effects." Applied Sciences 12, no. 1 (January 3, 2022): 440. http://dx.doi.org/10.3390/app12010440.

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Soil structure has significant influences on the mechanical behaviors of natural soils, although it is rarely considered in previous cavity expansion analyses. This paper presents an undrained elastoplastic solution for cylindrical cavity expansion in structured soils, considering the destructuration effects. Firstly, a structural ratio was defined to denote the degree of the initial structure, and the Structured Cam Clay (SCC) model was employed to describe the subsequent stress-induced destructuration, including the structure degradation and crushing. Secondly, combined with the large strain theory, the considered problem was formulated as a system of first-order differential equations, which can be solved in a simplified procedure with the introduced auxiliary variable. Finally, the significance and efficiency of the present solution was demonstrated by comparing with the previous solutions, and parametric studies were also conducted to investigate the effects of soil structure and destructuration on the cavity expansion process. The results show that the soil structure has pronounced effects on the mechanical behavior of structured soils around the cavity. For structured soils, a cavity pressure that is larger than the corresponding reconstituted soils when the cavity expands to the same radius is required, and the effective stresses first increase to a peak value before decreasing rapidly with soil structure degradation and crushing. The same final critical state is reached for soils with different degrees of the initial structure, which indicates that the soil structure is completely destroyed during the cavity expansion. With the increase of the destructuring index, the soil structure was destroyed more rapidly, and the stress release during the plastic deformation became more significant. Moreover, the present solution was applied in the jacking of a casing during the sand compact pile installation and in situ self-boring pressuremeter (SBPM) tests, which indicates that the present solution provides an effective theoretical tool for predicting the behavior of natural structured soils around the cavity.

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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.

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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.

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Timofeeva, Yulia, Elena Sukhacheva, Boris Aparin, Vitaly Terleev, Aleksandr Nikonorov, and Luka Akimov. "Soil structure of sand quarries territory." E3S Web of Conferences 157 (2020): 02017. http://dx.doi.org/10.1051/e3sconf/202015702017.

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Anthropogenic activities are one of the leading factors of soil differentiation. Significant changes in the soil cover occur as a result of the construction of quarries. The mining industry causes the complete degradation of soils in large areas, the change of the natural soil cover and elevation around the quarries, the destruction of vegetation, disturbs biodiversity of the territory and the death of ecosystems. Soil cover structures of mining quarries have been considered on the example of the Leningrad region such as a natural conditions and environmental peculiarities typical for the whole Russian North-West area. Decoding and diagnostic signs of anthropogenic transformed soils were determined. The type and degree of transformation of the component composition, the contrast and heterogeneity of the soil cover, intercomponent connections, the shape and figure of the internal organization of the of soil cover structures have been identified. The complexity of the anthropogenic transformed soils cover is illustrated by “key site”.

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Cotching, W. E., and K. C. Belbin. "Assessment of the influence of soil structure on soil strength/soil wetness relationships on Red Ferrosols in north-west Tasmania." Soil Research 45, no. 2 (2007): 147. http://dx.doi.org/10.1071/sr06113.

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The relationship of soil wetness to soil strength in Red Ferrosols was compared between fields of well structured to degraded soil structure. Soil structure was assessed using a visual rating. Soil resistance measurements were taken over a range of soil wetness, using a recording penetrometer. Readings were taken as the soil dried by evapotranspiration after both irrigation and rainfall events. The influence of soil wetness on penetration resistance was greater on fields with degraded structure than on well-structured fields. In fields with degraded structure, the wetter the soil, the smaller were the penetration resistance values. Field soil structure score was negatively correlated with the slope of the line relating soil wetness and penetration resistance at 150–300 mm depth. The structurally degraded fields had a highly significant relationship between penetration resistance and soil wetness at 150–300 mm depth. In well-structured fields, variations in soil wetness had less effect on penetration resistance. These results indicate that visual assessment can be used with confidence to assess Ferrosol structure. The implications for soil management are that fields with degraded soil structure have greater resistance to root growth at drier moisture contents than well-structured fields. Consequently, farmers need to keep degraded soils wetter with more frequent irrigation than well-structured soils, to ensure optimum plant growth.

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Wilpert, Klaus von. "Forest Soils—What’s Their Peculiarity?" Soil Systems 6, no. 1 (January 6, 2022): 5. http://dx.doi.org/10.3390/soilsystems6010005.

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Mankind expects from forests and forest soils benefits like pure drinking water, space for recreation, habitats for nature-near biocenoses and the production of timber as unrivaled climate-friendly raw material. An overview over 208 recent articles revealed that ecosystem services are actually the main focus in the perception of forest soil functions. Studies on structures and processes that are the basis of forest soil functions and ecosystem services are widely lacking. Therefore, additional literature was included dealing with the distinct soil structure and high porosity and pore continuity of forest soils, as well as with their high biological activity and chemical soil reaction. Thus, the highly differentiated, hierarchical soil structure in combination with the ion exchange capacity and the acid buffering capacity could be described as the main characteristics of forest soils confounding the desired ecosystem services. However, some of these functions of forest soils are endangered under the influence of environmental change or even because of forest management, like mono-cultures or soil compaction through forest machines. In the face of the high vulnerability of forest soils and increased threads, e.g., through soil acidification, it is evident that active soil management strategies must be implemented with the aim to counteract the loss of soil functions or to recover them.

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Xu, Bin Bin. "Influence of Soil Structure on the Mechanical Response of Soft Soil." E3S Web of Conferences 38 (2018): 03027. http://dx.doi.org/10.1051/e3sconf/20183803027.

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Usually the natural sedimentary soils possess structure more or less, which makes their mechanical response much different from the fully remolded soils. In this paper, the influence of soil structure on the mechanical response such as compressibility, shear, permeability is literately reviewed. It is found that the compressibility and consolidation behavior of structured and remolded soils can be divided clearly before or after the structural yield stress. The stress-strain relationship can be divided into two segments before and after the structural yield stress. Before the yield stress, the curve is elevating and after the yield stress the curve is decreasing. The increasing rate of pore water pressure increases after the soil reached yield stress.

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Saye, Steven R., Bryan P. Kumm, and Alan J. Lutenegger. "Estimating overconsolidation ratio (OCR) in structured and unstructured cohesive soil with field vane tests referencing soil index properties." Canadian Geotechnical Journal 58, no. 1 (January 2021): 125–41. http://dx.doi.org/10.1139/cgj-2019-0414.

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Estimation of the preconsolidation stress and overconsolidation ratio (OCR) in uniform cohesive soils using a field vane is variably impacted by the combined effects of soil type and plasticity, geologic history, structured vs. unstructured behavior, and the presence of sand or organic matter. Published empirical correlations for cohesive soils consider the effects of soil type and plasticity, but significant variability can occur with changes in soil structure and organic matter content for specific instances. The adaption of the “stress history and normalized soil engineering properties” (SHANSEP) format improves the characterization of overconsolidated soils using field vane tests by applying a proposed empirical approach to identify structured soils from unstructured soils and updating the SHANSEP-based approach to separately evaluate structured and unstructured soils. Validation of the correlation coefficients for individual projects will be needed as the approach is applied to new geologic materials and with potentially different field vane equipment and laboratory testing procedures used to characterize the soils. This additional testing provides an opportunity to improve the correlations for specific conditions and reduce the variability in the OCR assessments.

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Dissertations / Theses on the topic "Soils Soil structure"

Grieger, Gayle. "The effect of mineralogy and exchangeable magnesium on the dispersive behaviour of weakly sodic soils /." Title page, table of contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phg8478.pdf.

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Nelson, Paul Netelenbos. "Organic matter in sodic soils : its nature, decomposition and influence on clay dispersion." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phn4281.pdf.

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Bibliography: leaves 147-170. Aims to determine the influence of sodicity on the nature and decomposition of organic matter; and the influence of organic matter and its components on the structural stability of sodic soils.

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Barzegar, Abdolrahman. "Structural stability and mechanical strength of salt-affected soils." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phb296.pdf.

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Copies of author's previously published articles in pocket inside back cover. Bibliography: leaves 147-160. This thesis outlines the factors affecting soil strength and structural stability and their interrelationship in salt-affected soils. The objectives of this study are to investigate the influence of clay particles on soil densification and mellowing, the mellowing of compacted soils and soil aggregates as influenced by solution composition, the disaggregation of soils subjected to different sodicities and salinities and its relationship to soil strength and dispersible clay and the effect of organic matter and clay type on aggregation of salt-affected soils.

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Duval, Jean. "Assessing porosity characteristics as indicators of compaction in a clay soil." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59275.

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Persistent soil compaction by heavy-axle-load vehicles is a growing concern for the long-term productivity of clay soils. For optimum soil management, however, we must be able to evaluate adequately soil structural damages. This study compares different methods of assessing soil structure as affected by compaction and subsoiling treatments in a clay soil under corn production.
The tests used were: total porosity as calculated from densimeter readings and from soil cores; structural porosity; water desorption characteristics; and soil profile examination. These tests were performed in three layers of 20 cm and evaluation was based on their practicality and their ability to differentiate between treatments and to correlate with corn yield.
The results confirm that total porosity is a poor indicator of compaction in the subsoil. In soil profile assessments, ped descriptions were preferable to examination of pores. Water content and saturation deficit at $-$4.0 and $-$100 kPa were the best indicators of treatments and plant response.

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Li, Xu. "Dual-porosity structure and bimodal hydraulic property functions for unsaturated coarse granular soils /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202009%20LI.

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Miller, Kendall Mar 1958. "INTERPRETIVE SCHEME FOR MODELING THE SPATIAL VARIATION OF SOIL PROPERTIES IN 3-D (AUTOCORRELATION, STOCHASTIC, PROBABILITY)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276981.

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Wick, Abbey Foster. "Soil aggregate and organic matter dynamics in reclaimed mineland soils." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1400961671&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Chen, Chien-chang. "Shear induced evolution of structure in water-deposited sand specimens." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/22724.

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Reeve, Jennifer Rose. "Soil quality, microbial community structure, and organic nitrogen uptake in organic and conventional farming systems." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Summer2007/j_reeve_071207.pdf.

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Harris, Mark Anglin. "The effects of green manure on soil structure in calcareous sodic and non-sodic soils /." Title page, Contents and Summary only, 1995. http://web4.library.adelaide.edu.au/theses/09A/09ah315.pdf.

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Books on the topic "Soils Soil structure"

Fanning, Delvin Seymour. Soil. New York: Wiley, 1989.

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Zitong, Gong, Zhang Ganlin, and Qi Zhiping, eds. Hainan dao tu xi gai lun. Beijing: Ke xue chu ban she, 2004.

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Di︠u︡karev, A. G. Landshaftno-dinamicheskie aspekty taezhnogo pochvoobrazovanii︠a︡ v Zapadnoĭ Sibiri. Tomsk: Izd-vo Nauch.-tekhn. lit-ry, 2005.

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The soil as a reactor: Modelling processes in the soil. Cremlingen, West Germany: Catena Verlag, 1987.

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M, Huang P., Senesi N, and Buffle J. 1943-, eds. Structure and surface reactions of soil particles. Chichester: Wiley, 1998.

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V, Andrianova L., Nikhileeva T. P, and Dugarov V. I, eds. Statisticheskie modeli stroenii͡a︡ i svoĭstv pochv Zabaĭkalʹi͡a︡ i ikh chislennai͡a︡ klassifikat͡s︡ii͡a︡ dli͡a︡ prikladnykh t͡s︡eleĭ: Na primere gidrotermicheskikh parametrov. Ulan-Udė: Rossiĭskai͡a︡ akademii͡a︡ nauk, Sibirskoe otd-nie, Buri͡a︡tskiĭ nauch. t͡s︡entr, In-t biologii, 1993.

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Ershov, I͡U︡. I. doktor biologicheskikh nauk., ed. Strukturoobrazovanie v torfi͡a︡nykh pochvakh. Novosibirsk: "Nauka," Sibirskoe otd-nie, 1992.

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Dupigny, Lesley-Ann. An analysis of textural variability in a forest soil: Final draft of Bachelor of Science thesis. [Toronto: Scarborough Campus, University of Toronto, 1989.

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Schaetzl, Randall J. Soils: Genesis and geomorphology. Cambridge, UK: Cambridge University Press, 2005.

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1961-, Anderson Sharon, ed. Soils: Genesis and geomorphology. Cambridge: Cambridge University Press, 2005.

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Book chapters on the topic "Soils Soil structure"

Ali Maroof, M., Danial Rezazadeh Eidgahee, and Ahmad Mahboubi. "Particle Morphology Effect on the Soil Pore Structure." In Lecture Notes in Civil Engineering, 1–10. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1260-3_1.

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AbstractThe soil fabric can be expressed as a network model. Granular media voids connectivity and constriction size distribution may lead to movement of air, fluids, and solids in the soil, and therefore affect the chemical, physical and mechanical properties of soils. Understanding the soil voids areas and their interconnection might be helpful in understanding different phenomena such as transport in porous media, water retention, fluid flow in the soil, soil contamination, internal erosion, suffusion, and filtration. In addition, specifying the soil voids interconnectivity can help researchers and practical engineers to provide the best rehabilitation and remediation approaches. The pore network was investigated in the current study, assuming the soil particles to be similar to discrete spheres and particles with different shapes. Also, based on the modelling techniques, the profiles of pore connectivity and constriction size distribution were assessed.

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Papagiannakis, A. T., S. Bin-Shafique, and R. L. Lytton. "Retaining Structure-Unsaturated Soil Interaction." In Unsaturated Soils: Research and Applications, 269–74. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31343-1_34.

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Lazebnik, George E., and Gregory P. Tsinker. "Stiff Foundations on Cohesive and Nonhomogeneous Soils." In Monitoring of Soil-Structure Interaction, 153–64. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-5979-5_9.

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Levy, Guy J., and David N. Warrington. "Polyacrylamide Addition to Soils: Impacts on Soil Structure and Stability." In Functional Polymers in Food Science, 9–31. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781119108580.ch2.

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Poulsen, Tjalfe G. "Gas Permeability in Soils as Related to Soil Structure and Pore System Characteristics." In Quantifying and Modeling Soil Structure Dynamics, 155–85. Madison, WI, USA: American Society of Agronomy and Soil Science Society of America, 2015. http://dx.doi.org/10.2134/advagricsystmodel3.c7.

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Feda, J. "Mechanisms of Collapse of Soil Structure." In Genesis and Properties of Collapsible Soils, 149–72. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0097-7_8.

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Miroshnychenko, Mykola, Oleksandr Kruglov, Pavlo Nazarok, and Stanislav Kovalenko. "Identification of the Structure of Soil Cover by Magnetic Susceptibility." In Soils Under Stress, 57–68. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-68394-8_6.

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Desai, C. S. "Dynamic Soil-Structure Interaction with Constitutive Modelling for Soils and Interfaces." In Finite Element Methods for Nonlinear Problems, 191–207. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82704-4_11.

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Hinojosa, M. Belén, Roberto García-Ruiz, and José A. Carreira. "Utilizing Microbial Community Structure and Function to Evaluate the Health of Heavy Metal Polluted Soils." In Soil Biology, 185–224. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02436-8_9.

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Booltink, H. W. G., J. Bouma, and P. Droogers. "Use of Fractals to Describe Soil Structure." In Physical Nonequilibrium in Soils Modeling and Application, 157–93. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003076094-6.

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Conference papers on the topic "Soils Soil structure"

Bryant, John T., Derek V. Morris, Sean P. Sweeney, Michael D. Gehrig, and J. Derick Mathis. "Tree Root Influence on Soil-Structure Interaction in Expansive Clay Soils." In Shallow Foundation and Soil Properties Committee Sessions at ASCE Civil Engineering Conference 2001. Reston, VA: American Society of Civil Engineers, 2001. http://dx.doi.org/10.1061/40592(270)7.

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Hajjat, Jumanah, Marcelo Sánchez, and Guillermo Avila. "Unsaturated and Saturated Soil-Structure Interface Effect on Cracking Behavior of Soil." In Second Pan-American Conference on Unsaturated Soils. Reston, VA: American Society of Civil Engineers, 2018. http://dx.doi.org/10.1061/9780784481707.037.

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Zhang, Xiong, and Jean-Louis Briaud. "Coupled Hydro-Mechanical Stress Soil-Structure Interaction Simulation." In Fourth International Conference on Unsaturated Soils. Reston, VA: American Society of Civil Engineers, 2006. http://dx.doi.org/10.1061/40802(189)181.

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Tugzhzhav, Oyuunchimeg, Uyanga Munkhzhargal, and Munkhnasan Sarantuyaa. "SOME GEOCHEMICAL FEATURES OF SOILS IN THE JARGALANT REGION IN WESTERN MONGOLIA." In Treshnikov readings – 2021 Modern geographical global picture and technology of geographic education. Ulyanovsk State Pedagogical University named after I. N. Ulyanov, 2021. http://dx.doi.org/10.33065/978-5-907216-08-2-2021-75-78.

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The article examines the patterns of distribution and basic characteristics of the main soil types, reveals the geochemical structure of soils of the arid territory in the central part of the Great Lakes Basin, for example, the region of the DJargalant mountain based on the fundamental theoretical foundations of world soil geography and soil geochemistry. The establishment on this basis of the features of structures within the high mountain, low mountain landscapes and landscapes of the lakeside plain.

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Yin, Ling Ling, King Him Lo, and Su Su Wang. "Effect of Pile-Soil Interaction on Structural Dynamics of Large MW Scale Offshore Wind Turbines in Shallow-Water Western GOM." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-42320.

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The effect of pile-soil interaction on structural dynamics is investigated for a large offshore wind turbine in the hurricane-prone Western Gulf of Mexico (GOM) shallow water. The offshore wind turbine has a rotor with three 100-meter blades and a mono-tower structure. Loads on the turbine rotor and the support structure subject to a 100-year return hurricane are determined. Several types of soil are considered and modeled with a distributed spring system. The results reveal that pile-soil interaction affects dynamics of the turbine support structure significantly, but not the wind rotor dynamics. Designed with proper pile lengths, natural frequencies of the turbine structure in different soils stay outside dominant frequencies of wave energy spectra in both normal operating and hurricane sea states, but stay between blade passing frequency intervals. Hence potential resonance of the turbine support structure is not of concern. A comprehensive Campbell diagram is constructed for safe operation of the offshore turbine in different soils.

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Williams, Peter J., Thomas L. White, and J. Kenneth Torrance. "The Significance of Soil Freezing for Stress Corrosion Cracking." In 1998 2nd International Pipeline Conference. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/ipc1998-2054.

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The microstructure of soils (the arrangement of pores and voids, aggregation and surface characteristics of particles) is substantially modified by freezing. Soils so modified differ, in a number of important properties, from soils not previously frozen. Furthermore, each time a soil is frozen there is a redistribution of particles, moisture and solutes. Corrosion of buried pipes is known to be related to the ground conditions. Accordingly the particular nature of frozen ground needs consideration in this respect. Studies of microstructure of samples of freezing, frozen and unfrozen soils, many obtained from a full-scale experimental study of the effects of freezing on a buried pipeline, have provided an explanation for measured changes in bulk geotechnical properties of the materials. The microstructure viewed by optical microscopy, reveals the soil structure as having a complex and striking dependence on freezing history. Scanning electron microscopy shows further details in clay rich soils. Freezing at temperatures occurring in nature normally does not convert all the soil water to ice. The effects of particle surface forces is to reduce the freezing point of the water nearest a mineral surface. The distribution of solutes is radically altered, with pockets of high concentration interconnected by a liquid phase of varying concentration. A variety of other effects, relating to chemical and mechanical properties of soils subjected to freezing, have been demonstrated or can be postulated. Some of these are important in corrosion phenomena. The stresses that have been shown to occur in a pipe as a result of frost heave in the freezing soil, will also tend to increase the possibility of stress corrosion cracking.

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Aparin, Boris. "REHABILITATION AGRICULTURE SYSTEMS ON DEGRADED SOILS IN THE HUMID ZONE." In Land Degradation and Desertification: Problems of Sustainable Land Management and Adaptation. LLC MAKS Press, 2020. http://dx.doi.org/10.29003/m1670.978-5-317-06490-7/35-39.

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Most of the arable soils that became deposits at the turn of the 21st century have lowered their agroecological potential. This is due to degradation processes, which manifest in various forms depending on the structure of the soil cover, types of anthropogenic impact, and farming systems used. Assessing theagroecological potential of degraded soils is becoming more complicated due to global climate change. Thus, the problem arises of developing rehabilitation soil-conservation farming systems adapted to climate change and modern socio-economic conditions.

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Pishchulina, L., A. Sergeeva, and Lidiya Yablonskih. "SOIL MONITORING OF THE FOREST PARK ZONE OF THE CITY OF LISKI VORONEZH REGION." In Reproduction, monitoring and protection of natural, natural-anthropogenic and anthropogenic landscapes. FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov, 2022. http://dx.doi.org/10.34220/rmpnnaal2021_86-89.

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The article presents information on the results of monitoring the ecological state of soils of the green infrastructure of the small town of Liski. It has been established that in the city and suburban areas, mainly soddy-forest sandy soils are widespread, which are a background component of the structure of the soil cover of natural landscape complexes. The analysis is carried out and the characteristics of the physicochemical and chemical properties of soddy forest soils are given. It is shown that the soils of the suburban area have more favorable properties than similar soils of the urban area.

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Chen, Zheng-han, Xiang-wei Fang, Shu-guo Sun, Gang Li, Yun Xie, and Zai-hua Lu. "Test Research on Structure-Damage Evolution and Thermal-Mechanical Characteristics of Unsaturated Expansive Soil." In Fourth International Conference on Unsaturated Soils. Reston, VA: American Society of Civil Engineers, 2006. http://dx.doi.org/10.1061/40802(189)145.

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Mirshekari, Morteza, and Majid Ghayoomi. "Challenges in the Seismic Modelling of Soil-Structure Systems with Unsaturated Soils Using Geotechnical Centrifuge." In Geotechnical and Structural Engineering Congress 2016. Reston, VA: American Society of Civil Engineers, 2016. http://dx.doi.org/10.1061/9780784479742.177.

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Reports on the topic "Soils Soil structure"

Shenker, Moshe, Paul R. Bloom, Abraham Shaviv, Adina Paytan, Barbara J. Cade-Menun, Yona Chen, and Jorge Tarchitzky. Fate of Phosphorus Originated from Treated Wastewater and Biosolids in Soils: Speciation, Transport, and Accumulation. United States Department of Agriculture, June 2011. http://dx.doi.org/10.32747/2011.7697103.bard.

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Beneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levelsBeneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levels that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction.

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Wells, Aaron, Tracy Christopherson, Gerald Frost, Matthew Macander, Susan Ives, Robert McNown, and Erin Johnson. Ecological land survey and soils inventory for Katmai National Park and Preserve, 2016–2017. National Park Service, September 2021. http://dx.doi.org/10.36967/nrr-2287466.

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This study was conducted to inventory, classify, and map soils and vegetation within the ecosystems of Katmai National Park and Preserve (KATM) using an ecological land survey (ELS) approach. The ecosystem classes identified in the ELS effort were mapped across the park, using an archive of Geo-graphic Information System (GIS) and Remote Sensing (RS) datasets pertaining to land cover, topography, surficial geology, and glacial history. The description and mapping of the landform-vegetation-soil relationships identified in the ELS work provides tools to support the design and implementation of future field- and RS-based studies, facilitates further analysis and contextualization of existing data, and will help inform natural resource management decisions. We collected information on the geomorphic, topographic, hydrologic, pedologic, and vegetation characteristics of ecosystems using a dataset of 724 field plots, of which 407 were sampled by ABR, Inc.—Environmental Research and Services (ABR) staff in 2016–2017, and 317 were from existing, ancillary datasets. ABR field plots were located along transects that were selected using a gradient-direct sampling scheme (Austin and Heligers 1989) to collect data for the range of ecological conditions present within KATM, and to provide the data needed to interpret ecosystem and soils development. The field plot dataset encompassed all of the major environmental gradients and landscape histories present in KATM. Individual state-factors (e.g., soil pH, slope aspect) and other ecosystem components (e.g., geomorphic unit, vegetation species composition and structure) were measured or categorized using standard classification systems developed for Alaska. We described and analyzed the hierarchical relationships among the ecosystem components to classify 92 Plot Ecotypes (local-scale ecosystems) that best partitioned the variation in soils, vegetation, and disturbance properties observed at the field plots. From the 92 Plot Ecotypes, we developed classifications of Map Ecotypes and Disturbance Landscapes that could be mapped across the park. Additionally, using an existing surficial geology map for KATM, we developed a map of Generalized Soil Texture by aggregating similar surficial geology classes into a reduced set of classes representing the predominant soil textures in each. We then intersected the Ecotype map with the General-ized Soil Texture Map in a GIS and aggregated combinations of Map Ecotypes with similar soils to derive and map Soil Landscapes and Soil Great Groups. The classification of Great Groups captures information on the soil as a whole, as opposed to the subgroup classification which focuses on the properties of specific horizons (Soil Survey Staff 1999). Of the 724 plots included in the Ecotype analysis, sufficient soils data for classifying soil subgroups was available for 467 plots. Soils from 8 orders of soil taxonomy were encountered during the field sampling: Alfisols (<1% of the mapped area), Andisols (3%), Entisols (45%), Gelisols (<1%), Histosols (12%), Inceptisols (22%), Mollisols (<1%), and Spodosols (16%). Within these 8 Soil Orders, field plots corresponded to a total of 74 Soil Subgroups, the most common of which were Typic Cryaquents, Typic Cryorthents, Histic Cryaquepts, Vitrandic Cryorthents, and Typic Cryofluvents.

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Fuchs, Marcel, Jerry Hatfield, Amos Hadas, and Rami Keren. Reducing Evaporation from Cultivated Soils by Mulching with Crop Residues and Stabilized Soil Aggregates. United States Department of Agriculture, 1993. http://dx.doi.org/10.32747/1993.7568086.bard.

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Field and laboratory studies of insulating properties of mulches show that the changes they produce on the heat balance and the evaporation depend not only on the intrinsic characteristics of the material but also on the structure of air flow in boundary layer. Field measurements of the radiation balance of corn residue showed a decrease of reflectivity from 0.2 to 0.17 from fall to spring. The aerodynamic properties of the atmospheric surface layer were turbulent, with typical roughness length of 12 to 24 mm. Evaporation from corn residue covered soils in climate chambers simulating the diurnal course of temperature in the field were up to 60% less than bare soil. Wind tunnel studies showed that turbulence in the atmospheric boundary layer added a convective component to the transport of water vapor and heat through the mulches. The decreasing the porosity of the mulch diminished this effect. Factors increasing the resistance to vapor flow lowering the effect of wind. The behavior of wheat straw and stabilized soil aggregates mulches were similar, but the resistance to water of soil aggregate layer with diameter less than 2 mm were very large, close to the values expected from molecular diffusion.

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Avnimelech, Yoram, Richard C. Stehouwer, and Jon Chorover. Use of Composted Waste Materials for Enhanced Ca Migration and Exchange in Sodic Soils and Acidic Minespoils. United States Department of Agriculture, June 2001. http://dx.doi.org/10.32747/2001.7575291.bard.

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Restoration of degraded lands and the development of beneficial uses for waste products are important challenges facing our society. In addition there is a need to find useful and environmentally friendly applications for the organic fractions of municipal and other solid waste. Recent studies have shown that composted wastes combined with gypsum or gypsum-containing flue gas desulfurization by-products enhance restoration of sodic soils and acidic minespoils. The mechanism by which this synergistic effect occurs in systems at opposite pH extremes appears to involve enhanced Ca migration and exchange. Our original research objectives were to (1) identify and quantify the active compost components involved in Ca transport, (2) determine the relative affinity of the compost components for Ca and competing metals in the two soil/spoil systems, (3) determine the efficacy of the compost components in Ca transport to subjacent soil and subsequent exchange with native soil cations, and (4) assess the impacts of compost enhanced Ca transport on soil properties and plant growth. Acidic mine spoils: During the course of the project the focus for objective (1) and (2) shifted more towards developing and evaluating methods to appropriately quantify Ca2+ and Al3+ binding to compost derived dissolved organic matter (DOM). It could be shown that calcium complexation by sewage sludge compost derived DOM did not significantly change during the composting process. A method for studying Al3+ binding to DOM was successfully developed and should allow future insight into DOM-Al3+ interactions in general. Laboratory column experiments as well as greenhouse experiments showed that in very acidic mine spoil material mineral dissolution controls solution Al3+ concentration as opposed to exchange with Ca2+. Therefore compost appeared to have no effect on Al3+ and Ca2+ mobility and did not affect subsoil acidity. Sodic alkaline soils: Batch experiments with Na+ saturated cation exchange resins as a model for sodic soils showed that compost home cations exchanged readily with Na+. Unlike filtered compost extracts, unfiltered compost suspensions also significantly increased Ca2+ release from CaCO3. Soil lysimeter experiments demonstrated a clear impact of compost on structural improvement in sodic alkaline soils. Young compost had faster, clearer and longer lasting effects on soil physical and chemical properties than mature compost. Even after 2 growing seasons differences could still be observed. Compost increased Ca2+ concentration in soil solution and solubility of pedogenic CaCO3 that is highly insoluble under alkaline conditions. The solubilized Ca2+ efficiently exchanged Na+ in the compost treated soils and thus greatly improved the soil structure.

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Russo, David, and William A. Jury. Characterization of Preferential Flow in Spatially Variable Unsaturated Field Soils. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7580681.bard.

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Preferential flow appears to be the rule rather than the exception in field soils and should be considered in the quantitative description of solute transport in the unsaturated zone of heterogeneous formations on the field scale. This study focused on both experimental monitoring and computer simulations to identify important features of preferential flow in the natural environment. The specific objectives of this research were: (1) To conduct dye tracing and multiple tracer experiments on undisturbed field plots to reveal information about the flow velocity, spatial prevalence, and time evolution of a preferential flow event; (2) To conduct numerical experiments to determine (i) whether preferential flow observations are consistent with the Richards flow equation; and (ii) whether volume averaging over a domain experiencing preferential flow is possible; (3) To develop a stochastic or a transfer function model that incorporates preferential flow. Regarding our field work, we succeeded to develop a new method for detecting flow patterns faithfully representing the movement of water flow paths in structured and non-structured soils. The method which is based on application of ammonium carbonate was tested in a laboratory study. Its use to detect preferential flow was also illustrated in a field experiment. It was shown that ammonium carbonate is a more conservative tracer of the water front than the popular Brilliant Blue. In our detailed field experiments we also succeeded to document the occurrence of preferential flow during soil water redistribution following the cessation of precipitation in several structureless field soils. Symptoms of the unstable flow observed included vertical fingers 20 - 60 cm wide, isolated patches, and highly concentrated areas of the tracers in the transmission zone. Soil moisture and tracer measurements revealed that the redistribution flow became fingered following a reversal of matric potential gradient within the wetted area. Regarding our simulation work, we succeeded to develop, implement and test a finite- difference, numerical scheme for solving the equations governing flow and transport in three-dimensional, heterogeneous, bimodal, flow domains with highly contrasting soil materials. Results of our simulations demonstrated that under steady-state flow conditions, the embedded clay lenses (with very low conductivity) in bimodal formations may induce preferential flow, and, consequently, may enhance considerably both the solute spreading and the skewing of the solute breakthrough curves. On the other hand, under transient flow conditions associated with substantial redistribution periods with diminishing water saturation, the effect of the embedded clay lenses on the flow and the transport might diminish substantially. Regarding our stochastic modeling effort, we succeeded to develop a theoretical framework for flow and transport in bimodal, heterogeneous, unsaturated formations, based on a stochastic continuum presentation of the flow and a general Lagrangian description of the transport. Results of our analysis show that, generally, a bimodal distribution of the formation properties, characterized by a relatively complex spatial correlation structure, contributes to the variability in water velocity and, consequently, may considerably enhance solute spreading. This applies especially in formations in which: (i) the correlation length scales and the variances of the soil properties associated with the embedded soil are much larger than those of the background soil; (ii) the contrast between mean properties of the two subdomains is large; (iii) mean water saturation is relatively small; and (iv) the volume fraction of the flow domain occupied by the embedded soil is relatively large.

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Workman, Austin, and Jay Clausen. Meteorological property and temporal variable effect on spatial semivariance of infrared thermography of soil surfaces for detection of foreign objects. Engineer Research and Development Center (U.S.), June 2021. http://dx.doi.org/10.21079/11681/41024.

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The environmental phenomenological properties responsible for the thermal variability evident in the use of thermal infrared (IR) sensor systems is not well understood. The research objective of this work is to understand the environmental and climatological properties contributing to the temporal and spatial thermal variance of soils. We recorded thermal images of surface temperature of soil as well as several meteorological properties such as weather condition and solar irradiance of loamy soil located at the Cold Regions Research and Engineering Lab (CRREL) facility. We assessed sensor performance by analyzing how recorded meteorological properties affected the spatial structure by observing statistical differences in spatial autocorrelation and dependence parameter estimates.

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Snyder, Victor A., Dani Or, Amos Hadas, and S. Assouline. Characterization of Post-Tillage Soil Fragmentation and Rejoining Affecting Soil Pore Space Evolution and Transport Properties. United States Department of Agriculture, April 2002. http://dx.doi.org/10.32747/2002.7580670.bard.

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Tillage modifies soil structure, altering conditions for plant growth and transport processes through the soil. However, the resulting loose structure is unstable and susceptible to collapse due to aggregate fragmentation during wetting and drying cycles, and coalescense of moist aggregates by internal capillary forces and external compactive stresses. Presently, limited understanding of these complex processes often leads to consideration of the soil plow layer as a static porous medium. With the purpose of filling some of this knowledge gap, the objectives of this Project were to: 1) Identify and quantify the major factors causing breakdown of primary soil fragments produced by tillage into smaller secondary fragments; 2) Identify and quantify the. physical processes involved in the coalescence of primary and secondary fragments and surfaces of weakness; 3) Measure temporal changes in pore-size distributions and hydraulic properties of reconstructed aggregate beds as a function of specified initial conditions and wetting/drying events; and 4) Construct a process-based model of post-tillage changes in soil structural and hydraulic properties of the plow layer and validate it against field experiments. A dynamic theory of capillary-driven plastic deformation of adjoining aggregates was developed, where instantaneous rate of change in geometry of aggregates and inter-aggregate pores was related to current geometry of the solid-gas-liquid system and measured soil rheological functions. The theory and supporting data showed that consolidation of aggregate beds is largely an event-driven process, restricted to a fairly narrow range of soil water contents where capillary suction is great enough to generate coalescence but where soil mechanical strength is still low enough to allow plastic deforn1ation of aggregates. The theory was also used to explain effects of transient external loading on compaction of aggregate beds. A stochastic forInalism was developed for modeling soil pore space evolution, based on the Fokker Planck equation (FPE). Analytical solutions for the FPE were developed, with parameters which can be measured empirically or related to the mechanistic aggregate deformation model. Pre-existing results from field experiments were used to illustrate how the FPE formalism can be applied to field data. Fragmentation of soil clods after tillage was observed to be an event-driven (as opposed to continuous) process that occurred only during wetting, and only as clods approached the saturation point. The major mechanism of fragmentation of large aggregates seemed to be differential soil swelling behind the wetting front. Aggregate "explosion" due to air entrapment seemed limited to small aggregates wetted simultaneously over their entire surface. Breakdown of large aggregates from 11 clay soils during successive wetting and drying cycles produced fragment size distributions which differed primarily by a scale factor l (essentially equivalent to the Van Bavel mean weight diameter), so that evolution of fragment size distributions could be modeled in terms of changes in l. For a given number of wetting and drying cycles, l decreased systematically with increasing plasticity index. When air-dry soil clods were slightly weakened by a single wetting event, and then allowed to "age" for six weeks at constant high water content, drop-shatter resistance in aged relative to non-aged clods was found to increase in proportion to plasticity index. This seemed consistent with the rheological model, which predicts faster plastic coalescence around small voids and sharp cracks (with resulting soil strengthening) in soils with low resistance to plastic yield and flow. A new theory of crack growth in "idealized" elastoplastic materials was formulated, with potential application to soil fracture phenomena. The theory was preliminarily (and successfully) tested using carbon steel, a ductile material which closely approximates ideal elastoplastic behavior, and for which the necessary fracture data existed in the literature.

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Furey, John, Austin Davis, and Jennifer Seiter-Moser. Natural language indexing for pedoinformatics. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/41960.

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The multiple schema for the classification of soils rely on differing criteria but the major soil science systems, including the United States Department of Agriculture (USDA) and the international harmonized World Reference Base for Soil Resources soil classification systems, are primarily based on inferred pedogenesis. Largely these classifications are compiled from individual observations of soil characteristics within soil profiles, and the vast majority of this pedologic information is contained in nonquantitative text descriptions. We present initial text mining analyses of parsed text in the digitally available USDA soil taxonomy documentation and the Soil Survey Geographic database. Previous research has shown that latent information structure can be extracted from scientific literature using Natural Language Processing techniques, and we show that this latent information can be used to expedite query performance by using syntactic elements and part-of-speech tags as indices. Technical vocabulary often poses a text mining challenge due to the rarity of its diction in the broader context. We introduce an extension to the common English vocabulary that allows for nearly-complete indexing of USDA Soil Series Descriptions.

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VanderGheynst, Jean, Michael Raviv, Jim Stapleton, and Dror Minz. Effect of Combined Solarization and in Solum Compost Decomposition on Soil Health. United States Department of Agriculture, October 2013. http://dx.doi.org/10.32747/2013.7594388.bard.

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In soil solarization, moist soil is covered with a transparent plastic film, resulting in passive solar heating which inactivates soil-borne pathogen/weed propagules. Although solarization is an effective alternative to soil fumigation and chemical pesticide application, it is not widely used due to its long duration, which coincides with the growing season of some crops, thereby causing a loss of income. The basis of this project was that solarization of amended soil would be utilized more widely if growers could adopt the practice without losing production. In this research we examined three factors expected to contribute to greater utilization of solarization: 1) investigation of techniques that increase soil temperature, thereby reducing the time required for solarization; 2) development and validation of predictive soil heating models to enable informed decisions regarding soil and solarization management that accommodate the crop production cycle, and 3) elucidation of the contributions of microbial activity and microbial community structure to soil heating during solarization. Laboratory studies and a field trial were performed to determine heat generation in soil amended with compost during solarization. Respiration was measured in amended soil samples prior to and following solarization as a function of soil depth. Additionally, phytotoxicity was estimated through measurement of germination and early growth of lettuce seedlings in greenhouse assays, and samples were subjected to 16S ribosomal RNA gene sequencing to characterize microbial communities. Amendment of soil with 10% (g/g) compost containing 16.9 mg CO2/g dry weight organic carbon resulted in soil temperatures that were 2oC to 4oC higher than soil alone. Approximately 85% of total organic carbon within the amended soil was exhausted during 22 days of solarization. There was no significant difference in residual respiration with soil depth down to 17.4 cm. Although freshly amended soil proved highly inhibitory to lettuce seed germination and seedling growth, phytotoxicity was not detected in solarized amended soil after 22 days of field solarization. The sequencing data obtained from field samples revealed similar microbial species richness and evenness in both solarized amended and non-amended soil. However, amendment led to enrichment of a community different from that of non-amended soil after solarization. Moreover, community structure varied by soil depth in solarized soil. Coupled with temperature data from soil during solarization, community data highlighted how thermal gradients in soil influence community structure and indicated microorganisms that may contribute to increased soil heating during solarization. Reliable predictive tools are necessary to characterize the solarization process and to minimize the opportunity cost incurred by farmers due to growing season abbreviation, however, current models do not accurately predict temperatures for soils with internal heat generation associated with the microbial breakdown of the soil amendment. To address the need for a more robust model, a first-order source term was developed to model the internal heat source during amended soil solarization. This source term was then incorporated into an existing “soil only” model and validated against data collected from amended soil field trials. The expanded model outperformed both the existing stable-soil model and a constant source term model, predicting daily peak temperatures to within 0.1°C during the critical first week of solarization. Overall the results suggest that amendment of soil with compost prior to solarization may be of value in agricultural soil disinfestations operations, however additional work is needed to determine the effects of soil type and organic matter source on efficacy. Furthermore, models can be developed to predict soil temperature during solarization, however, additional work is needed to couple heat transfer models with pathogen and weed inactivation models to better estimate solarization duration necessary for disinfestation.

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Dolgopolova, N. V., I. Ya Pigorev, and V. V. Grudinkina. METHODOLOGY OF DESIGNING CROWNS, AGROCHEMICAL CHARACTERISTIC OF SOILS AND THE OPTIMUM STRUCTURE OF SOWING AREAS IN ADAPTIVE LANDSCAPE AGRICULTURE (ON THE EXAMPLE OF CENTRAL BLACK SOIL). ФГБОУ ВО Курская ГСХА, 2018. http://dx.doi.org/10.18411/issn1997-0749.2018-06-14.

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