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1
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.
Testo completo
2
Odell, Simon Paul. "Microbial reclamation of alkaline sodic soils /". Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09ASOP/09asopo23.pdf.
Testo completo
3
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.
Testo completoAbstract (sommario):
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.
4
Nathan, Muhammad. "Clay movement in a saline-sodic soil toposequence". Title page, contents and summary only, 2001. http://web4.library.adelaide.edu.au/theses/09A/09an274.pdf.
Testo completoAbstract (sommario):
Includes bibliographical references (leaves 78-86) In the Herrmanns sub-catchment in the Mt. Lofty Ranges (near Mt. Torrens) soil sodicity was the dominant factor in causing clay to disperse in the eroded area along the foot slopes, wheras in non-eroded areas of the mid-slopes and on the stream banks, the dispersive power of sodicity was attenuated by the flocculative power of other soil properties.
5
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.
Testo completo
6
Fotovat, Amir. "Chemistry of indigenous Zn and Cu in the soil-water system : alkaline sodic and acidic soils". Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phf761.pdf.
Testo completoAbstract (sommario):
Copies of author's previously published articles inserted. Bibliography: leaves 195-230. In this study the soil aqueous phase chemistry of Zn and Cu in alkaline sodic soils are investigated. The chemistry of trace metal ions at indigenous concentrations in alkaline sodic soils are reported. Metal ions at low concentrations are measured by the graphite furnace atomic absorption spectrometry (GFAAS) technique.
7
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.
Testo completoAbstract (sommario):
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.
8
Chorom, Mostafa. "Behaviour of alkaline sodic soils and clays as influenced by pH and particle change". Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phc551.pdf.
Testo completoAbstract (sommario):
Copies of author's previously published articles inserted. Bibliography: leaves 173-196. The objective of this thesis is to investigate the factors affecting swelling and dispersion of alkaline sodic soils containing lime and the ways to manage these soils to improve their physical condition. Studies on pure clay systems are included to understand the fundamental process involved in swelling and dispersion of pure and soil clays.
9
Suriadi, Ahmad. "Structural stability and Na-Ca exchange selectivity of soils under sugarcane trash management". Title page, Contents and Abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09ASOM/09asoms961.pdf.
Testo completo
10
Nawar, Niman K. "Reclamation of saline-sodic soils by poly (vinyl alcohol)". Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258170.
Testo completo
11
Breker, Maria Christine. "Influence of Amendments on Chemical and Biological Properties of Sodic Soils". Thesis, North Dakota State University, 2016. https://hdl.handle.net/10365/28268.
Testo completoAbstract (sommario):
Improving productivity of sodic soils has become a concern in North Dakota because of the desire for more land for producing crops. Field and incubation studies were conducted to determine the impacts of different amendments (flue-gas desulfurization gypsum, sugar beet processing by-product lime, and langbeinite) on the chemical and biological properties of two sodic soils. The field study evaluated the amendment effects on the chemical conditions of the soil and the impact on alfalfa yield and quality. Differences were not observed in percent sodium (%Na) in the first 17 months and alfalfa yield was not impacted by the treatments except for the high rate of langbeinite. The incubation study investigated the effects of amendments on both the chemical and biological properties of the soil. Spent lime increased the cumulative respiration but was not impacted by gypsum or langbeinite. Labile carbon (C) was negatively correlated with %Na and electrical conductivity (EC).North Dakota Soybean Council
12
Armstrong, Andrew Shaw Braidwood. "Salt and water dynamics in saline and sodic clay soils". Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330126.
Testo completo
13
Misra, Dinesh. "Early tree-soil-root relationships of Prosopis, Eucalyptus, and Azadirachta planted on sodic soils". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0026/MQ50395.pdf.
Testo completo
14
Johnston, Christopher R. "Soil chemical and physical changes resulting from irrigation with coalbed natural gas co-produced water effects of soil amendments and water treatments /". Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445033651&sid=10&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Testo completo
15
Hoyningen, Huene Bernhard von. "Subirrigation of maize using saline-sodic water". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41782.
Testo completoAbstract (sommario):
A field subirrigation experiment, using saline-sodic water, was carried out on a loamy sand soil in southwestern Quebec. The experimental field was divided into 16 plots with 4 treatments; saline-sodic water, "fresh" water, controlled drainage and non-irrigated. Each treatment had four replicates. Maize yield, hydraulic conductivity, salt concentration, and salt movement through the soil were recorded in all plots.No significant difference in maize yield occurred between plots irrigated with saline-sodic or fresh water in any of the three years. Irrigated maize plots yielded approximately 30% more than non-irrigated plots.
Hydraulic conductivity reductions in the saline plots were noted in May 1986, after the first snowmelt. From statistical analysis carried out, it appears that the saline-sodic water had an effect on hydraulic conductivity, significant at the 0.05 level.
From the measurements taken from piezometer stations, located throughout the field, salt concentrations and salt movement through the saturated soil profile were determined. Using salt concentration data from both irrigation water and soil water, an average effective field porosity was calculated with a computer program. The results obtained were within 4% of those obtained in laboratory tests. Moreover, the program was then used to model the salt balance of the soil from May 85 to May 87. Results indicated that most salts were removed with the rainfall and snowmelt of the winter months of 85/86 and 86/87.
16
Gebrekidan, Heluf Tedla. "Evaluation of the potential use of langbeinite (potassium sulfate / magnesium sulfate) as a reclaiming material for sodic and saline sodic soils". Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187424.
Testo completoAbstract (sommario):
Soil sodicity/salinity and scarcity of water are important constraints of agricultural development in arid lands. Excessive exchangeable sodium of sodic and saline sodic soils cause swelling of clays and dispersion of colloidal particles, and results in poor soil-water-air relationships. Reclaiming sodic and saline sodic soils involves the displacement of exchangeable sodium and its subsequent leaching from the root zone. This further depends upon the choice of chemical or cation to exchange for sodium and the quality and availability of water for leaching. Therefore, a series of experiments including soil characterization, laboratory batch studies, column leaching studies and greenhouse crop response studies were conducted to evaluate the potential use of langbeinite as a reclaiming material for saline sodic soil. Both the Grabe clay loam and the Guest clay soils met the requirements of a saline sodic soil category. The Grabe clay loam was more strongly saline sodic than the Guest clay soil, and was therefore used in the subsequent studies. In the batch studies involving a 1:1 soil:water extracts, langbeinite proved to be more efficient than gypsum in replacing exchangeable Na especially at higher levels of applied amendments. In the column studies, the amount of exchangeable Na displaced due to gypsum and langbeinite was the same when high amount (4 pore volumes) of water was used for leaching. However, langbeinite removed considerably higher amounts of sodium than gypsum with the use of lower volumes of leaching water. Accordingly, savings of over 9 acre-inch of irrigation water per acre of reclaimed land can be realized by using langbeinite over gypsum to lower the ESP of the soil to about 10% when both amendments are applied at a rate of 12 tons/ha. The hydraulic conductivity (HC) of the soil increased significantly due to application of both gypsum and langbeinite and decreased due to leaching with increasing pore volumes of water. Although steady state HC was not attained with the use of gypsum, the HC of the soil treated with gypsum was higher than the langbeinite treated soil after leaching with 4 pore volumes of water. Similarly, seed germination and dry matter yield of lima bean plants responded to the application of gypsum and langbeinite and leaching both with Safford irrigation water and Tucson tap water. Such responses both to the amendments and volumes of leaching water were of a higher magnitude with langbeinite than with gypsum.
17
Dikinya, Oagile. "The effects of self-filtration on saturated hydraulic conductivity in sodic sandy soils". University of Western Australia. School of Earth and Geographical Sciences, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0051.
Testo completoAbstract (sommario):
[Truncated abstract] Self-filtration is here defined as particle detachment and re-deposition causing re-arrangement of the particles and therefore pore space which affects water flow in soil by decreasing hydraulic conductivity. This is of particular important in soils which are susceptible to structural breakdown. The objective of this thesis was to examine the dynamics of the self-filtration process in sodic sandy soils as affected by ionic strength and soil solution composition. The temporal changes of hydraulic conductivity and the elution of fine particles from soil columns were used as the main criteria to assess selffiltration. Two porous media exhibiting significantly different structural cohesion were examined, one a loamy sand (Balkuling soil) from agricultural land use and the second a mining residue from mineral sands operations . . . The effects of the composition of mixed calcium (Ca) and sodium (Na) ions in solution (sodium adsorption ratio (SAR)) on the exchange behaviour and saturated hydraulic conductivity were examined by carrying out batch binary exchange and saturated column transport experiments. A strong preference for Ca2+ ions in the exchange complex was observed for both soils. Generally K/Ko was found to decrease with increasing sodium adsorption ratio with the more structured Balkuling soil maintaining K/Ko for SARs 3 and 5 at an electrolyte concentration of 100 mmol/L. However measurements at the critical threshold and turbidity concentrations at a SAR of 15 revealed structural breakdown of the pore matrix system attributed to various extents of slaking, swelling, dispersion and decreases of pore radii as a result of selffiltration during leaching. These experiments illustrate the wide range of complex interactions involving clay mineralogy, solution composition and structural factors which can influence the extent of mobilization, transport and re-deposition of colloidal particles during the leaching process in soil profiles.
18
Dikinya, Oagile. "The effects of self-filtration on saturated hydraulic conductivity in sodic sandy soils /". Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0051.
Testo completo
19
Alfatesh, Ibrahim Yahya 1956. "Sodium, calcium, and magnesium changes in soils upon application of saline-sodic waters". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/191889.
Testo completoAbstract (sommario):
The purpose of this research was to study the effects of different types and amount of saline-sodic waters on the cation concentration changes in solution extracts, drainage waters, and on the exchange complex of two soils differing in their textures, exchange properties, and lime content. The composition of solution extracts, drainage waters and exchange phases of both soils was closely related to the cationic composition of the irrigation waters. Salt accumulation in the soils increased with increasing salinity of the applied water. Salts were distributed uniformally with depth after 8 and 11 applications. Exchangeable sodium was directly related to the SAR of the applied solutions. The SAR of soil leachates and solution extracts increased as the amount of salt and applied water increased. The two soils responded differently to the type and amount of the applied water. Both soils released some Ca and Mg to the soil solution from the dissolution of primary minerals and cation exchange reaction. Both soils were affected by the salinity and sodicity of the applied solution.
20
Marwan, M. M. "Changes in physical and chemical properties of saline-sodic soils during removal of salts by leaching with water". Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234663.
Testo completo
21
Bhojvaid, Padam Parkash. "Dynamics of soil-plant relationships after afforestation of sodic soils with Prosopis juliflora, Swartz DC, in Haryana, India". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35112.pdf.
Testo completo
22
Jayasekera, Samudra. "An investigation into modification of the engineering properties of salt affected soils using electrokinetics". Thesis, University of Ballarat, 2008. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/34198.
Testo completoAbstract (sommario):
Soil salinity (due to ingress of excess amounts of dissolved salts in soil pores) and soil sodicity (due to excess amounts of sodium ions attached to the clay surface) are significant forms of land degradation in many parts of the world in particular in arid and semi arid regions. In Australia, soil salinity has long been identified as the major form of land degradation and the greatest environmental threat. Saline soils cover almost 6% of Australia’s land mass and impose severe threats on agricultural productivity and built infrastructure with an estimated annual loss of $250 million. In recent years, ‘soil sodicity’ is recognised as a far more significant form of land degradation and a severe environmental problem both in terms of affected land area and impact on the environment than is salinity as a problem in Australia. One third of Australian land mass is occupied by sodic soils costing an estimated $2 billion each year in lost production alone, with further significant impacts on the economy due to extensive damage to infrastructure facilities and the environment. [...]Doctor of Philosophy
23
Jayasekera, Samudra. "An investigation into modification of the engineering properties of salt affected soils using electrokinetics". University of Ballarat, 2008. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/15710.
Testo completoAbstract (sommario):
Soil salinity (due to ingress of excess amounts of dissolved salts in soil pores) and soil sodicity (due to excess amounts of sodium ions attached to the clay surface) are significant forms of land degradation in many parts of the world in particular in arid and semi arid regions. In Australia, soil salinity has long been identified as the major form of land degradation and the greatest environmental threat. Saline soils cover almost 6% of Australia’s land mass and impose severe threats on agricultural productivity and built infrastructure with an estimated annual loss of $250 million. In recent years, ‘soil sodicity’ is recognised as a far more significant form of land degradation and a severe environmental problem both in terms of affected land area and impact on the environment than is salinity as a problem in Australia. One third of Australian land mass is occupied by sodic soils costing an estimated $2 billion each year in lost production alone, with further significant impacts on the economy due to extensive damage to infrastructure facilities and the environment. [...]Doctor of Philosophy
24
Amini, Sevda. "Carbon Dynamics in Salt-Affected Soils". Thesis, Griffith University, 2015. http://hdl.handle.net/10072/366584.
Testo completoAbstract (sommario):
Salt-affected soils are soils with high concentrations of dissolved mineral salts in their profiles to the extent that such dissolved salts adversely affect crop production. Globally 75 countries have been recognized as having vast areas of salt-affected lands. Australia, United States, Turkey, India, Iran, Iraq, Mexico, Syria, Pakistan, and China are countries with serious salinity problems. In a recent estimate, nearly 831 million hectares of land are salt-affect worldwide. Salt-affected soils mostly exist in arid and semiarid regions of the world and many salt-affected wastelands have been productive lands in the past. Worldwide about 95 million hectares of soils are under primary salinization (i.e salinity occurs naturally in soils and water) whereas 77 million hectares suffer from secondary salinization (as a result of human activities and ever rising groundwater table). Also, 23% of arable lands of the world are affected by salinity while further 10% are saline sodic soils. In Australia sodicity affects about 17 million hectares of land. The key objectives of this study were to 1) study the effects of chemical (Gypsum) and organic (plant material) amendments on carbon dynamic in soil aggregate. 2) evaluate the effects of an organic amendment (Alkaline biochar) on chemical, biological and C stocks of “saline soils” with different salinity levels. 3) study the effects of two types of biochar (Acidic and Alkaline) as an organic amendment on physical, chemical, biological and C stocks of a “saline-sodic” soil. 4) and finally, study the effect of vegetation cover on carbon dynamics in different depths of saline-sodic soils (phytoremediation).Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment.
Science, Environment, Engineering and Technology
Full Text
25
Sessoms, Holly Nicol. "Water use potential and salt tolerance of riparian species in saline-sodic environments". Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/sessoms/SessomsH0805.pdf.
Testo completo
26
Muller, Felicity. "The effect of sodicity severity and depth on irrigated cotton production at Hillston, New South Wales". Thesis, Faculty of Agriculture, Food & Natural Resources, 2006. http://hdl.handle.net/2123/912.
Testo completo
27
Wamono, Anthony Walekhwa. "Effects of Calcium Based Surface Amendments on Hydraulic Conductivity and Selected Physical Properties of Subsurface Drained Sodic Soils". Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25661.
Testo completoAbstract (sommario):
Managing excess soil water in agricultural fields in the Northern Great Plains through subsurface drainage increases the risk of sodification in high-risk soils. Leaching sodic soils with low electrical conductivity (EC) water, rainfall, may result in the swelling of soil, dispersion of clay particles and consequently the breakdown of soil structure leading to changes in physical and mechanical properties of soils (e.g., reduced infiltration, hard-setting and reduced trafficability). In this dissertation, the effectiveness of calcium amendments of gypsum and spent lime, a byproduct of the processing sugar beets, with water-management treatments of free drainage (FD) and no drainage (ND) on improving physical properties of the soil were examined.
The first objective was to evaluate the effects of drainage and surface treatments on the penetration resistance (PR). The second objective was to use infiltration tests with a mini-disk tension infiltrometer and a Cornell sprinkle infiltrometer to investigate changes in hydraulic properties. Lastly, a drawbar dynamometer was used to measure draft on a chisel plow as it was pulled across the plots by a tractor equipped with an auto-guidance system and instrumentation interfaced with the controller area network of the tractor.
The results show that the PR values of plots with gypsum application at high rate of 22.4 Mg ha-1 (GH) were significantly higher than other surface amendments. GH increased the hydraulic conductivity of the soil matrix compared to spent lime application at rate of 22.4 Mg ha-1 (SL); however, the overall flow of water through the soil profile, including the soil matrix and the macropores, was not affected. Both GH and gypsum application at high rate of 11.2 Mg ha-1 (GL) lowered the drawbar power requirements compared to spent lime application. For many farmers, drainage enables early planting and the adding of ameliorants will safeguard against further sodification of their fields.USDA
Natural Resources Conservation Service
Conservation Innovation Grants program, under the project entitled, "Reducing Sodification in High Risk Northern Great Plains Soils," agreement number 69-3A75-12-185
North Dakota Agricultural Experiment Station
CNH Industrial Engineering Test Center (Fargo, North Dakota)
North Dakota Water Resources Research Institute
28
Wentworth, Fitzwilliam Stephen Neville. "Improving the sustainability of irrigated maize (Zea mays) on sodic soils in the Lachlan Valley of New South Wales". Thesis, The University of Sydney, 2001. https://hdl.handle.net/2123/27799.
Testo completoAbstract (sommario):
In recent years, the expression “Sustainable Agriculture” has entered public discourse on
social, economic, and ecological issues, especially in the context of analysing the
negative effects of certain crop production practices. For example, efficient irrigation is
now essential due to the ever-changing political environment in respect to water access.
Furthermore, interest in alternative weed control methods has grown with an emphasis
on reducing tillage and pesticide use.
To achieve a sustainable agro-industry, new systems for crop production must be found.
One such system, for irrigated maize on sodic soils in the Lachlan Valley was
hypothesized and tested in the research reported here. This system incorporated the use
of drip irrigation on permanent beds, with the use of residue retention through zero
tillage and the use of legume cover crops over winter. Growth, yield and water use
efliciency of maize grown under different irrigation methods were measured in order to
provide information towards the formulation of guidelines for best irrigation practice
management. The new cropping system was compared to the standard practices of the
Lachlan Valley such as flood irrigation and conventional tillage.
In an experiment conducted to compare four irrigation methods border check (B)
irrigation used 6.3ML of irrigation water; drip (D) irrigation reduced this volume by 52%
and furrow (F) and permanent bed (P) irrigation had intermediate water requirements.
From 15 DAS, crop LAI and dry matter were lowest in B and highest in D compared
with other irrigation methods. Despite the large difi‘erences in crop growth, grain yields
were similar in all treatments except B, which was reduced by up to 15%. The water use
efficiency of yield ranged from 1.80 (in border check) to 4.05 (in drip) t/Ml due to the
large differences in the quantity of water applied to each treatment.
During the production of the legume cover crop over winter, dry matter yields were
lower than expected from the literature. Poor growth may have been attributable to
herbicide residues remaining in the soil from the maize crop. Experiments were
conducted to test the tolerance of the clover species Trifolium subterraneum cv.
Nungarin, Trifolium balansae cv. Paradana and Trifolium vesiculosum cv. Zulu to the
herbicides atrazine and metolachlor, that are commonly used in maize production
systems in the district. All three clover species showed low tolerances to the herbicides,
with subterranean clover showing the highest tolerance. Substantial retardation of
growth occurred in the subterranean clover with atrazine concentrations of less that 1%
of the recommended rate (9 g ai/ha).
Sustainable production of irrigated maize on sodic soils in the Lachlan Valley of New
South Wales will involve the adoption by farmers of Best Irrigation Management
Practices (BIMP’s). Such practices identified in the literature or by experimentation in
this thesis include the following: i) the application to soil of gypsum and lime; ii) the use
of permanent beds for cropping, and preferably with drip irrigation; iii) the production of
a winter cover crop; and, iv) the use of zero-tillage where practical.
Management of cropping systems will continue to be influenced strongly by economic
factors, as growers try to remain viable. Soil erosion, continuous cropping and soil
fertility, interactions between crops, and nitrogen cycling and management must be
addressed. Farming practices which include reduced tillage, crop rotation, opportunity
cropping, legumes and fertilizers can be better utilised by farmers to improve
sustainability and subsequently profitability.
29
PESSOA, Luiz Guilherme Medeiros. "Analysis of salt affected soils in semiarid landscapes of Pernambuco, Brazil". Universidade Federal Rural de Pernambuco, 2012. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5229.
Testo completoAbstract (sommario):
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The sodification and salinization of soil are the main types of degradation of semiarid of Pernambuco. In extreme cases, the vegetation does not develop in these soils, making them desertified. Consequently, there is an abandonment of these areas. Nowadays, a may does not exist identifying these areas for Pernambuco state, which could be done through tools such as Remote Sensing and GIS. This study was conducted in order to identify and diagnose areas affected by salinization and sodification in the semiarid area of Pernambuco. A study was conducted in the laboratory to understand the spectral behavior of different types of salts in two representative soils. These soils were leached with saline solutions of CaCl2.2H2O, MgCl2.2H2O, KCl and NaCl at concentrations of 0.5, 1 and 2 mol L-1. There was an increase in reflectance of crusts with increasing wavelength; however, there was a reduction in the reflectance with increasing salt concentrations of the solution applied to the four kinds of salts, in both soils. The intensity of reflectance was increased in the salts studied: NaCl > KCl > MgCl2.2H2O > CaCl2.2H2O, where the Arenosol showed higher reflectance in relation to Fluvisol, between concentrations and different salts. Afterward, with the intent to understand the spectral behavior of different salt levels and their correlation with the soil properties, a field investigation was conducted in which soil samples were collected from four representative watersheds: Brígida, Terra Nova, Pajeú and Moxotó that have varying degrees of salinity and sodicity within the semiarid region of Pernambuco. It was observed that there was an increase in reflectance with increasing wavelength to the spectral response in all salinity and sodicity levels and the variable Exchangeable Sodium Percentage (ESP) had good correlation coefficients obtained with the positive spectral reflectance bands in virtually all soil sample tested, while the variable fine sand obtained negative coefficients. For the identification of these areas affected by salts and sodium, a map showing the spatial distribution of pH, electrical conductivity, ESP and sodium adsorption ratio (SAR) was done using a GIS tool. This study indicates that strongest association between cations and anions was the formation of sulfate and chlorides species where Na+ ions (exchangeable and soluble), HCO3- and Cl- ions are those that contribute most to the increase of salinity and sodicity in soils of the semiarid state of Pernambuco. The most area affected by sodium exchangeable and soluble is located especially on Moxotó watershed by the ESP and SAR levels. The Moxotó watershed indicated the worst levels of degradation by salinity and sodicity among the others. The EPIC model was used to assess how different management practices can predict corn yield and the soil salinity status. Three soil profiles from Moxotó watershed were used and the scenarios simulated included drip, furrow irrigation, and trigger irrigation (0.1 and 1 levels). This study found that the best irrigation strategy for corn yields grown was drip irrigation and trigger irrigation at a level of 0.1. However, for low water content applied, the trigger irrigation 1 should be used. Finally, with the intent to describe soil profiles in some critical areas, four soil profiles were evaluated. Soil samples were collected from the municipalities of Ibirimim, Parnamirim and Serra Talhada in Pernambuco. The soils studied have profiles with characteristic features of the Neossolos Flúvicos and Cambisolos soil. A strong relationship with these orders salinity problems in the semiarid region of Pernambuco was determined. The profiles in the study had high levels of salts and sodium with increasing depth. Furthermore, the predominance of fine particles in salt affected soils have been a factor which tended to complicate the recovery of these soils.
A sodificação e salinização do solo são os principais tipos de degradação do semi-árido de Pernambuco. Em casos extremos , a vegetação não se desenvolve nestes solos , tornando-as degradadas. Conseqüentemente, há um abandono destas áreas. Hoje em dia, pode não existir a identificação dessas áreas para o estado de Pernambuco , o que poderia ser feito por meio de ferramentas como o sensoriamento remoto e SIG. Este estudo foi realizado a fim de identificar e diagnosticar as áreas afetadas pela salinização e sodificação no semi-árido de Pernambuco. Um estudo foi realizado no laboratório para entender o comportamento espectral de diferentes tipos de sais em dois solos representativos. Estes solos foram lixiviados com soluções salinas de CaCl2.2H2O, MgCl2.2H2O, KCl e de NaCl em concentrações de 0,5, 1 e 2 mol L -1. Houve um aumento na reflectância de crostas com o aumento do comprimento de onda, no entanto, houve uma redução na reflectância com concentrações crescentes de sal da solução aplicada aos quatro tipos de sais , em ambos os solos. A intensidade de reflectância aumentada nos sais estudados: NaCl > KCl > MgCl2.2H2O > CaCl2.2H2O, onde o Arenosol apresentaram maior reflectância em relação ao Fluvissolo, entre as concentrações de sais e diferentes. Depois, com a intenção de entender o comportamento espectral de diferentes níveis de sal e sua correlação com as propriedades do solo, uma investigação de campo foi conduzido em que as amostras de solo foram coletadas a partir de quatro bacias representativas: Brígida , Terra Nova, Pajeú e Moxotó , que têm diferentes graus de salinidade e sodicidade na região semi-árida de Pernambuco. Observou-se que houve um aumento na reflectância com o aumento do comprimento de onda para a resposta espectral em todos os níveis de salinidade e sodicidade e a variável percentagem de sódio trocável (ESP ) tinha bons coeficientes de correlação obtidas com as bandas positivas de reflectância espectrais em virtualmente todas as amostras de solo testado enquanto a variável areia fina obteve coeficientes negativos. Para a identificação destas áreas afetadas por sais e sódio, um mapa que mostra a distribuição espacial de pH, condutividade elétrica, relação de adsorção de sódio ( SAR) e ESP foi feito usando uma ferramenta GIS. Este estudo indica que a forte associação entre cátions e ânions foi a formação de sulfato e espécies cloretos onde Na + íons ( trocável e solúvel), HCO3 - e Cl- íons são aqueles que mais contribuem para o aumento da salinidade e sodicidade dos solos do semi-árido estado de Pernambuco. A área mais afetada por sódio trocável e solúvel está localizado especialmente no Moxotó divisor de águas pelos níveis SAR e ESP. O divisor de águas Moxotó indicou os piores níveis de degradação de salinidade e sodicidade entre os outros. O modelo EPIC foi usado para avaliar a forma como as diferentes práticas de gestão pode prever o rendimento do milho e do estado da salinidade do solo. Três perfis de solo Moxotó na bacia, foram utilizados e os cenários simulados incluído por gotejamento, irrigação por sulco e irrigação trigger ( 0,1 e 1 níveis). Este estudo concluiu que a melhor estratégia de irrigação para a produção de milho cultivados era de irrigação por gotejamento e de irrigação gatilho a um nível de 0,1. No entanto, para um baixo teor de água aplicada, a um gatilho de irrigação deverão ser utilizados . Finalmente, com a intenção de descrever perfis de solo em algumas áreas críticas, foram avaliadas quatro perfis de solo. As amostras de solo foram coletadas a partir dos municípios de Ibirimim, Parnamirim e Serra Talhada, em Pernambuco. Os solos estudados têm perfis com características do Neossolos Flúvicos e Cambisolos solo. A forte relação com estas ordens de problemas de salinidade na região semi-árida de Pernambuco foi determinado. Os perfis no estudo tinham níveis elevados de sais e sódio com o aumento da profundidade. Além disso, a predominância de partículas finas em solos afetados por sais ter sido um fator que tende a complicar a recuperação desses solos.
30
King, Lyle A. "Land application with saline-sodic coalbed natural gas co-produced waters in Wyoming's Powder River Basin impacts to soil and biological properties /". Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1221694361&sid=3&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Testo completo
31
Nascimento, Alexandre Ferreira do. "Relações pedologia-geomorfologia-sedimentologia no Pantanal Norte". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-06072012-103745/.
Testo completoAbstract (sommario):
As relações entre os solos, material de origem e feições geomórficas são importantes para a compreensão da distribuição dos solos na paisagem e o entendimento de sua variabilidade espacial, sobretudo em ambientes úmidos (wetlands) de natureza sedimentar complexa. Procurou-se descrever e caracterizar os ambientes deposicionais de uma área de estudo, a Reserva Particular do Patrimônio Natural (RPPN) SESC Pantanal, buscando na sedimentologia e na geomorfologia que sistemas deposicionais e/ou erosivos formaram a paisagem e dessa forma interpretar as alterações ocorridas no relevo e nos sedimentos responsáveis pela gênese dos solos nesta parte do Pantanal Norte. Primeiramente foram realizados os estudos geomorfológicos com auxílio de ferramentas de sensoriamento remoto, expedições ao campo e sobrevoo da área. Nos compartimentos identificados foram realizadas tradagens mecanizadas profundas para se observar a arquitetura e a distribuição dos sedimentos. Os solos de 3 transeções representativas da área foram descritos, coletados e analisados, de forma a se determinar a configuração lateral e vertical dos horizontes e camadas, assim como a classificação pedológica e as evidências de processos pedogenéticos e sedimentares. A paisagem da RPPN SESC Pantanal foi modelada desde o Pleistoceno superior pela atividade de sistemas deposicionais distributários dominados por rios, caracterizados pela sucessiva construção e abandono de lóbulos deposicionais. O leque aluvial do rio São Lourenço é responsável pela maior parte dos depósitos e das formas do relevo observadas na área de estudo, enquanto que a planície do rio Cuiabá tem menor contribuição e se restringe à parte oeste. De maneira geral, os solos de canais antigos são Neossolos Quartzarênicos, de planície aluvial são Gleissolos, Plintossolos ou Neossolos/Cambissolos flúvicos, de diques e Murundus são Planossolos. Os nódulos de ferro e manganês podem ocorrer nos solos das porções elevadas e baixas (canais, diques e planícies antigas). Os mosqueados são mais contrastantes nas porções baixas (planícies antigas) e progressivamente se tornam menos evidentes à medida que se caminha para as porções elevadas (diques). Os contrastes e gradientes texturais são observados em todos os solos que possuem textura média ou mais fina, independente da porção do relevo, resultado da combinação de processos pedogenéticos e sedimentares. A argiluviação é evidente em todos os solos, porém com intensidade variável. A elevada porcentagem de sódio trocável ocorre com maior frequência nos solos das porções elevadas que não sofrem inundação (diques e murundus), contudo, é observado também em locais com ligeira influência de lâmina dágua. Dessa forma, por meio da abordagem solo x paisagem é possível identificar o controle geológico na distribuição e formação dos solos, como é o caso da presença de Neossolos Quartzarênicos nos canais antigos e a formação de contrastes texturais, e o controle pedogenético condicionado pelo relevo, como vem a ser o acúmulo de sódio. A abordagem integradora entre geomorfologia, sedimentologia e pedologia é indispensável para o entendimento da distribuição, variabilidade espacial e gênese de solos no Pantanal. Fora dessa ótica se torna difícil entender e estabelecer o papel efetivo da geogênese e da pedogênese nesse ambiente.Relationships between soils, parent material and geomorphic features are important to understand the distribution of soils in the landscape. This approach gains more importance when the landscape in study is too complex, e.g., wetlands constructed by depositional systems. Hence, the goal of this work was describe and characterize depositional environments of an unit of fauna and flora preservation (RPPN SESC Pantanal - nonprofits), searching for sedimentary and geomorphology evidences to know which depositional and/or erosional systems have shaped the landscape and then, to set up its relationship with weathering and changes in the system due to pedogenesis. Preliminary geomorphologic studies were developed using remote sensorial tools, fieldworks and flights over the studied area. In each Geomorphic features identified were done drilling procedures to assess the architecture and distribution of their sediments. Three representative soil sequences were described, sampled and analyzed to determine the lateral and vertical boundaries of horizons and layers, as well to find evidences of pedologic and sedimentological processes. Since late Pleistocene the landscape of the RPPN SESC Pantanal has been shaped by distributaries fluvial systems in which rivers were actives. The alluvial fan of the São Lourenço River was responsible by the most shapes and sediments observed in the studied area, while floodplain of the Cuiabá River had minor contribution and it is restricted to western part. Overall, the soils in the paleochannels are Arenosols; in paleofloodplains are Gleysols, Plinthosols or Fluvisols; in paleolevee and Murundus are Planosols. The mottles are common in the low portion of the relief (paleo-foodplain) and become progressively less apparent in the higher portions (paleo-levees). The textural horizons and vertical textural contrasts are observed in the soils of all geomorphic features that have loamy or finer textures, formed by pedogenic and geological processes. The clay illuviation is present in all those soils with textural horizons but in different intensities. The high levels of exchangeable sodium are observed in the soils located in the relief nonflooded (paleo-levee and murundus features). However, it can be also found in places with low flood. Therefore, the approach soil-landscape allows understanding the geological processes controlling the soil genesis and its distribution, as Arenosols in the paleochannels and the formation of textural contrasts. Moreover, it is possible to assess factors of soil formation (relief and whether) controlling the sodium accumulation. Thus the integration of geormorphology, sedimentology and pedology is needful to understand the distribution, spatial variability and genesis of soils in the Pantanal. Without this approach it seems hard to understand and establish the role of pedogenic and geological processes in this environment.
32
Silvertooth, J. C. "Saline and Sodic Soil Identification and Cotton Management". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001. http://hdl.handle.net/10150/147010.
Testo completo
33
Leal, Rafael Marques Pereira. "Efeito da irrigação com efluente de esgoto tratado em propriedades químicas de um latossolo cultivado com cana-de-açúcar". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-02072007-112919/.
Testo completoAbstract (sommario):
Já há muito tempo, a irrigação de cultivos agrícolas é praticada e considerada uma alternativa interessante e útil à disposição dos efluentes gerados pelas estações de tratamento de esgoto doméstico. Como qualquer outro resíduo, o uso agrícola implica em algumas vantagens, tais como o fornecimento contínuo de umidade e de determinados nutrientes, mas também desvantagens, ocasionando a adição de sais e de possíveis patógenos e contaminantes orgânicos. Apesar da utilização de efluente de esgoto tratado ser parte integrante da gestão hídrica em muitos países, até o presente momento não se conhece nenhum outro estudo onde se utilizou e avaliou os efeitos do mesmo na irrigação da cultura da cana-de-açúcar em condições tropicais. Para este fim, amostras de solo foram coletadas e analisadas em 3 diferentes épocas. A irrigação se estendeu por aproximadamente 16 meses. O arranjo experimental foi o de blocos com parcelas subdivididas no tempo, com 5 tratamentos e 4 repetições. Os tratamentos empregados foram: (i) Controle sem aplicação de nitrogênio (N) mineral e sem irrigação; (ii) T100 a T200, 50% da dose de N recomendada via fertilização mineral e irrigação com, respectivamente, 100, 125, 150 e 200% da demanda hídrica da cultura. A produtividade foi, por ocasião do primeiro corte, positivamente influenciada pela irrigação com efluente secundário de esgoto tratado (ESET). Alterações na nutrição da cultura da cana foram pouco evidentes (teores foliares, colmo e caldo). O ESET ocasionou ligeira amenização tanto da acidez ativa (pH) quanto potencial (H+Al) Os efeitos mais pronunciados da irrigação ocorreram para os parâmetros indicadores da sodicidade/salinidade do solo, com incrementos significativos nas concentrações de sódio (Na) trocável, Na solúvel, percentual de sódio trocável (PST) e condutividade elétrica da solução do solo (CE). Estes aumentos, por sua vez, estão relacionados aos elevados teores de Na do efluente em associação com as baixas concentrações de cálcio (Ca) e magnésio (Mg), relação expressa pelos valores de razão de adsorção de sódio (RAS) do efluente. Alterações nas concentrações dos demais cátions também ocorreram, entretanto, foram menos características. As perspectivas quanto à utilização do ESET na irrigação da cana-de-açúcar são bastante promissoras, haja vista a crescente importância da cultura e a predominância do cultivo em condições de sequeiro. Entretanto, a manutenção da produtividade da cultura em patamares elevados implicará, necessariamente, a adoção de práticas específicas de manejo a fim de superar as limitações impostas pelos incrementos dos indicadores de salinidade e sodicidade do sistema solo-planta.Since long ago agricultural irrigation has been practiced and considered as an interesting and beneficial alternative to the disposal of domestic sewage effluent. As all other residues, agricultural use implies both advantages, supplying crops continuously with water and some needed nutrients, and also disadvantages, through addition of salts and possible pathogens and organic contaminants. Although domestic sewage effluent is part of an integrated water management on many countries, none similar research is known involving sugarcane irrigation in tropical conditions. Three soil sampling campaigns were conducted. Soil samples were analyzed for quantifying acidity and exchangeable cations. Irrigation was applied for approximately 16 months. The experimental design was composed of a complete block, with five treatments and four replicates. Applied treatments where: (i) Control-no irrigation and no mineral-N applied; (ii)T100-T200, addition of 50% of the recommended mineral-N fertilization and irrigation with 100%, 125%, 150% and 200% of the crop water demand, respectively. Plant yield was positively affected by secondary-treated sewage effluent (STSE) irrigation. A small amelioration of the actual and potential soil acidity was observed for the highest dose of irrigation. The dominant effect of irrigation corresponded to increased concentrations of salinity-sodicity indicators, such as exchangeable sodium (Na), soluble Na, sodium saturation (ESP) and electrical conductivity of soil solution (EC). These increments are related to high Na concentrations for the applied effluent together with low calcium (Ca) and magnesium (Mg), relation expressed and defined by sodium adsorption ratio (SAR). Changes for other exchangeable cations also occurred, although not as clear and defined as for Na. Perspectives for STSE irrigation for sugarcane are promising, considering the growing importance of sugarcane crop and the very low cultivated area that is actually irrigated in the São Paulo State. However, the maintenance of crop productivity at high levels will necessarily imply the adoption of specific management practices suitable for ameliorating the limitations imposed by increasing salinity-sodicity parameters of the soil-plant system.
34
Speirs, Simon Douglas. "Characterising soil structural stability and form of sodic soil used for cotton production". Thesis, The University of Sydney, 2006. http://hdl.handle.net/2123/5817.
Testo completoAbstract (sommario):
In eastern Australia, Vertosols are widely utilised for the production of irrigated cotton (Gossypium hirsutum) due to their inherent fertility and large water–holding capacity. However, irrigated agriculture in eastern Australia is faced with a decline in the availability of good quality irrigation water sources i.e. waters with low electrolyte concentrations and small Na+ contributions. Consequently, alternative water resources that contain larger contributions of Na+ are becoming increasingly relevant as potential irrigation sources. It is known that the application of Na+ rich waters as irrigation has the potential to increase the Na+ content of the soil, and that this will affect the structural condition of Vertosols. However, the extent to which these poor quality water resources will influence the structural characteristics of different Vertosols is unknown. In addition to this knowledge gap, there is currently no suitable predictor of dispersive behaviour for this soil type, particularly where Vertosols are irrigated with different water quality solutions. The research conducted in this study aimed to characterise the impact of different increments of water quality on the structural stability of different Vertosols. Once this was concluded, the study looked to assess the impact of irrigation water quality on the structural stability, structural form and soil water retention properties of intact soil columns. Knowledge of the structural stability of the soils investigated was then used to derive a model describing the impact of water quality on the structural stability of different cotton producing soils. To achieve the aims nine different soil profiles were sampled from the Bourke, lower Gwydir, Hillston and lower Namoi cotton–producing regions. Eight of these soils are Grey and Black Vertosols with clay phyllosilicate suites dominated to different extents by 2:1 expanding clays, and the ninth soil is an illitic Red Vertosol containing small contributions of 2:1 expanding clays. The soils investigated have ESPs that range between 1 and 10, ECs of 0.1 to 1.2 dS m-1 and CECeff values that are largest for those soils that contain more 2:1 expanding clays. This study shows that the clay phyllosilicate suite of different Vertosols is the primary determinant of structural stability, structural form and soil water retention properties. For example, the Gwydir and Namoi soils contain more 2:1 expanding lattice phyllosilicate clays, have the largest CECeff values of all nine soils and are the most dispersive after all applied immersion treatments. The Bourke and Hillston soils contain less 2:1 expanding lattice clay, have smaller CECeff values and are generally more stable. Irrigation of structurally–intact soils with solutions of larger SARw resulted in larger exchangeable Na+ contents for each soil (and larger ESPs) and smaller contributions of exchangeable Ca2+ and Mg2+. For each soil, larger ESPs are reflected by decreased stability, but generally the soils dominated by 2:1 expansive clays are much less stable than the soils containing smaller contributions of these clay mineral types. Irrigating the structurally–intact Vertosols dominated by 2:1 expansive clays generally resulted in structural form attributes that do not indicate any impact of the applied water treatments, but the Vertosols with less of these mineral types tend to have less desirable structural form attributes after irrigation with solutions of larger Na+ content. Similarly, where the water retention properties of two soils were assessed, the illitic Red Vertosol has less structural pore space after treatment using the large SARw solutions, while the other soil (a Black Vertosol dominated by 2:1 expansive clays) does not show any differences between water retention properties that can be linked to irrigation water quality. These results were clarified for the water retention properties by the assessment of pore–solid space relations, which show both these soils to contain less solid space after irrigation with clean water or solutions of large SARw. This is attributed to increased swelling of clays in the presence of larger Na+ contributions, but both soils have different structural arrangements as shown by the water retention properties and structural form assessment. The red illitic Vertosol shows signs of structural collapse, while the black Vertosol maintains its structural arrangement. Finally, a model describing the structural stability of different Vertosols was developed from the stability assessment of soils, both in different water quality treatments and after the irrigation of structurally–intact columns. The model presented uses a surface response function to describe the impact of increased ECw and SARw of irrigation solutions on soil stability after immersion according to specific soil physico–chemical attributes. In this model increased exchangeable Na+, SAR and a larger CECeff (and consequently, an increased proportion of 2:1 swelling clays) are associated with increases in clay dispersion, while a smaller Ca2+:Mg2+ ratio, EC and less total clay are associated with decreases in clay dispersion.
35
Speirs, Simon Douglas. "Characterising soil structural stability and form of sodic soil used for cotton production". Faculty of Agriculture, Food and Natural Resources, 2006. http://hdl.handle.net/2123/5817.
Testo completoAbstract (sommario):
Doctor of Philosophy(PhD)In eastern Australia, Vertosols are widely utilised for the production of irrigated cotton (Gossypium hirsutum) due to their inherent fertility and large water–holding capacity. However, irrigated agriculture in eastern Australia is faced with a decline in the availability of good quality irrigation water sources i.e. waters with low electrolyte concentrations and small Na+ contributions. Consequently, alternative water resources that contain larger contributions of Na+ are becoming increasingly relevant as potential irrigation sources. It is known that the application of Na+ rich waters as irrigation has the potential to increase the Na+ content of the soil, and that this will affect the structural condition of Vertosols. However, the extent to which these poor quality water resources will influence the structural characteristics of different Vertosols is unknown. In addition to this knowledge gap, there is currently no suitable predictor of dispersive behaviour for this soil type, particularly where Vertosols are irrigated with different water quality solutions. The research conducted in this study aimed to characterise the impact of different increments of water quality on the structural stability of different Vertosols. Once this was concluded, the study looked to assess the impact of irrigation water quality on the structural stability, structural form and soil water retention properties of intact soil columns. Knowledge of the structural stability of the soils investigated was then used to derive a model describing the impact of water quality on the structural stability of different cotton producing soils. To achieve the aims nine different soil profiles were sampled from the Bourke, lower Gwydir, Hillston and lower Namoi cotton–producing regions. Eight of these soils are Grey and Black Vertosols with clay phyllosilicate suites dominated to different extents by 2:1 expanding clays, and the ninth soil is an illitic Red Vertosol containing small contributions of 2:1 expanding clays. The soils investigated have ESPs that range between 1 and 10, ECs of 0.1 to 1.2 dS m-1 and CECeff values that are largest for those soils that contain more 2:1 expanding clays. This study shows that the clay phyllosilicate suite of different Vertosols is the primary determinant of structural stability, structural form and soil water retention properties. For example, the Gwydir and Namoi soils contain more 2:1 expanding lattice phyllosilicate clays, have the largest CECeff values of all nine soils and are the most dispersive after all applied immersion treatments. The Bourke and Hillston soils contain less 2:1 expanding lattice clay, have smaller CECeff values and are generally more stable. Irrigation of structurally–intact soils with solutions of larger SARw resulted in larger exchangeable Na+ contents for each soil (and larger ESPs) and smaller contributions of exchangeable Ca2+ and Mg2+. For each soil, larger ESPs are reflected by decreased stability, but generally the soils dominated by 2:1 expansive clays are much less stable than the soils containing smaller contributions of these clay mineral types. Irrigating the structurally–intact Vertosols dominated by 2:1 expansive clays generally resulted in structural form attributes that do not indicate any impact of the applied water treatments, but the Vertosols with less of these mineral types tend to have less desirable structural form attributes after irrigation with solutions of larger Na+ content. Similarly, where the water retention properties of two soils were assessed, the illitic Red Vertosol has less structural pore space after treatment using the large SARw solutions, while the other soil (a Black Vertosol dominated by 2:1 expansive clays) does not show any differences between water retention properties that can be linked to irrigation water quality. These results were clarified for the water retention properties by the assessment of pore–solid space relations, which show both these soils to contain less solid space after irrigation with clean water or solutions of large SARw. This is attributed to increased swelling of clays in the presence of larger Na+ contributions, but both soils have different structural arrangements as shown by the water retention properties and structural form assessment. The red illitic Vertosol shows signs of structural collapse, while the black Vertosol maintains its structural arrangement. Finally, a model describing the structural stability of different Vertosols was developed from the stability assessment of soils, both in different water quality treatments and after the irrigation of structurally–intact columns. The model presented uses a surface response function to describe the impact of increased ECw and SARw of irrigation solutions on soil stability after immersion according to specific soil physico–chemical attributes. In this model increased exchangeable Na+, SAR and a larger CECeff (and consequently, an increased proportion of 2:1 swelling clays) are associated with increases in clay dispersion, while a smaller Ca2+:Mg2+ ratio, EC and less total clay are associated with decreases in clay dispersion.
36
Udy, Sandra. "Assessing Amendment Treatments for Sodic Soil Reclamation in Arid Land Environments". DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7670.
Testo completoAbstract (sommario):
Plugged and abandoned well pads throughout the Uintah Basin face reclamation challenges due to factors including a harsh climate, invasive species, and high salt loads. Finding ways to alleviate soil sodicity could improve soil reclamation success. Gypsum, sulfur, activated carbon, and Biochar are being applied to improve soil parameters negatively impacted by sodicity, but the direct impact of these amendments on Uintah Basin soils is still largely unknown. The aim of this study was two-fold. (1) Evaluate the effectiveness of gypsum, sulfuric acid, Biochar, activated carbon, and combinations of these amendments in reducing the impact of soil sodicity of the Desilt and Conglomerate soils by measuring amendment impact on percent dispersion, saturated hydraulic conductivity, crust bulk density, infiltration, and crust formation. (2) Compare a crust bulk density method using ImageJ to the clod wax density method and a modified linear extensibility percent equation to the linear extensibility percent equation to assess whether the novel methods can be used to accurately measure and calculate soil crust bulk density and shrink swell potential while reducing human error and analysis time.
37
Jassogne, Laurence. "Characterisation of porosity and root growth in a sodic texture-contrast soil". University of Western Australia. School of Plant Biology, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0092.
Testo completoAbstract (sommario):
In Australia a class of soils known as sodic duplex soils covers approximately 20% of the continent. Their defining characteristic is a sharp texture contrast between the A (or E) and B horizon. The upper B horizon at the point of contact with the E horizon is often highly sodic and of such a high strength that root growth and proliferation, water conductivity, aeration, water storage and water uptake are restricted. Roots growing in these soils rely on channels created by previous roots or cracks arising from shrink swell forces associated with seasonal wetting and drying. It has been suggested that by increasing the number of these channels in the subsoil, the structure and permeability of the subsoil would be increased as would be the number of preferential pathways for following generation roots. A biological approach for improving soil macroporosity would be to use plants that can grow through that hostile layer creating new channels. This is known as the primer plant concept. This concept is based on a better understanding of root soil interactions. It is accepted that root growth is influenced by the soil structure and the soil structure is influenced by root growth. However, a lot of these dynamics are still unknown. This project aims to contribute to improving that knowledge by investigating the use of modern techniques to study plant/root interactions in duplex soils. First macroporosity and mesoporosity were characterized in three dimensions using medical computer tomography and micro-tomography. Then the imaging methodology was improved by using a local and adaptive threshold technique based on indicator kriging instead of a global threshold. Using this new methodology, changes in porosity were analysed in intact samples when three different plant species were grown for 12 weeks. The plants were canola (Brassica napus); lucerne (Medicago sativum) and saltbush (Atriplex nummularia) hypothesizing saltbush would change the porosity more because it is a native plant species based on the primer plant concept. The results showed that the porosity changed significantly after root growth but no ii differences were found between plant species. The changes could also not all be attributed to root growth because cracks were also formed after 12 weeks. Therefore, the living roots were visualized and characterized using a new tracing algorithm 'rootviz'. This revealed that saltbush was growing more roots down through the profile. Lucerne seemed to grow roots down the profile as well but to a lesser extend. Both of these plants seemed to have more geotropic features than canola that seemed to grow more laterals and had a more exploratory behaviour.
38
Bailey, Danielle L. H. "Properties of soil profiles over sodic mine spoil 16 years after construction". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60410.pdf.
Testo completo
39
Alsharari, Musaed Amish. "Reclamation of fine-textured sodic soil using gypsum, langbeinite, and calcium chloride". Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/282872.
Testo completoAbstract (sommario):
The effects of various application rates of gypsum (Aqua-cal = finely ground gypsum), langbeinite (K₂SO₄.2MgSO₄), and CaCl₂ (anhydrous) on exchangeable Na removal and saturated hydraulic conductivity of a sodic soil were investigated under laboratory batch studies and laboratory column leaching studies. The research involved four phases of studies. Characterization of the soil and irrigation water indicated that the soil sample is sodic (ESP=35.3), ECₑ = 3.36 dS/m), and the irrigation water is moderately saline (EC = 2.2 dS/m). The laboratory batch studies showed that CaCl₂ and langbeinite treatments were more efficient in the displacement of Na than gypsum which increased with increasing application rate. In contrast, with gypsum, Na displacement increased to a maximum at an application rate of 7 tons/ha; then, no further increase in displacement was observed above that level. In the column leaching studies, applied amendments at equivalent rates of 7 tons/ha each and leaching with 5 pore volumes of irrigation water resulted in a total Na displacement of 60%, 80%, and 84% for gypsum, langbeinite, and CaCl₂, respectively. Moreover, the SAR of the soil was reduced significantly in the above treatments from 34.5 in the beginning of leaching to 6.80 for gypsum (G7), from 41.8 to 5.60 for langbeinite (L₇), and from 32.6 to 2.5 for CaCl₂(7). When amendments were applied at higher rates (G7 tons/ha gypsum and 13 tons/ha of each of CaCl₂ and langbeinite), the % total Na displaced was 60%, 100%, and 94% for gypsum, langbeinite, and CaCl₂, respectively. The corresponding SAR values at the end of reclamation were 6.80, 4.50, and 5.50 for gypsum, langbeinite, and CaCl₂, respectively. The combination treatments significantly improved the reclamation at 0.05 level as compared to the G7 treatment alone and saved more leaching water and displaced higher exchangeable Na as compared to the gypsum treatment (G7) alone. Saturated hydraulic conductivity (Ks) studies indicated that Ks was increased significantly when the amendments were applied at equivalent weights (7 tons/ha) and at higher application rates as compared to the control. The Ks of the gypsum treated soil (G7) was significantly higher than Ks of langbeinite and CaCl₂ treated soil at both equivalent rates and when applied at higher rates L13 and CaCl₂(13).
40
Ezlit, Younes Daw. "Modelling the change in conductivity of soil associated with the application of saline-sodic water". University of Southern Queensland, Faculty of Engineering and Surveying, 2009. http://eprints.usq.edu.au/archive/00006387/.
Testo completoAbstract (sommario):
[Abstract]: Scarcity of fresh water has led to use of low quality waters (high sodicity and salinity) that were considered unsuitable for irrigation in the past. Mismanagement of irrigation using this water can increase the potential for soil degradation and limit crop production in the long term. Irrigation using highly saline-sodic water requires appropriate management to avoid long term development of sodicity and salinity problems. The main factors that control the sodicity and salinity problems are maintenance of sufficientleaching and avoidance of soil structure degradation due to sodicity. The management options are determined by complex factors such as soil type and condition, water quality, irrigation practice and crop type.Investigating the management options for using highly saline-sodic water in irrigation experimentally is costly and time consuming. However, it could be done using anappropriate modelling tool that can handle the degradation of soil structure due to sodicity along with the chemical reaction system within the soil profile. UNSATCHEM has been widely used to model sodicity and salinity effects under irrigation. It has a feature to deal with soil structure degradation along with water and solute movement, major ion chemistry, CO2 production and movement and heat transfer under sodic conditions. It uses a hydraulic conductivity reduction function torelate the change of chemical properties to the change in hydraulic properties of the soil. However, the evaluation of the hydraulic conductivity reduction function underhigh sodicity during simulation has not been done. Hence, the core of this research project has been to improve quantification of soil structure degradation under sodicconditions and enhance the modelling of water and solute movement under sodic conditions. The hydraulic conductivity reduction function incorporated inUNSATCHEM was evaluated using data obtained from soil column experiments.Columns of two local soils were used in an experiment to investigate the effect on soil structural stability of different amendments to highly saline-sodic water rich withbicarbonates (EC = 4.6 dS/m and SAR = 117). The column experiments were used to examine the effect of reducing water pH to different levels using sulphuric acid andcombined gypsum and dilution treatments. It was found that reducing the pH of highly saline-sodic water did not enhance soil structural stability as the water applied hasnaturally high relative sodium concentrations. However, the application of diluted highly saline-sodic water amended with gypsum showed no significant effect on soil structure and permeability. It is concluded that different amendments associated with appropriate irrigation management can be applied to sustain irrigation and prevent long term salinity and sodicity problems.The data from the column experiments was used to evaluate the quantification of the soil structure degradation in UNSATCHEM. The resultant simulations for the soilcolumns showed that the estimated outflow and hydraulic conductivity were less than the experimental measurements, which suggested that the soil structure degradationwas not accounted for properly. The sodicity effect was accounted for in UNSATCHEM by a reduction function, which is a combined function of the McNeal (1968) clay swelling model and the Simunek et al. (1996) pH effect equations. The empirical pH effect equation accounts for the reduction of the conductivity due to increasing pH and clay swelling. The evaluation of UNSATCHEM under highly sodic conditions suggests that the hydraulic conductivity reduction function is limiting the UNSATCHEM performance.Consideration of the first term of the hydraulic conductivity reduction function (i.e. the McNeal (1968) clay swelling model) has highlighted the weaknesses of the McNeal model and led to develop a generic clay swelling model (GCSM). Calibration of the GCSM using the data of McNeal showed good agreement between the estimated and measured relative conductivity data. Further calibration of the GCSM using relative conductivity data obtained for five local soils also showed good agreement between the model estimation and the measured data.Coding of the generic clay swelling model into UNSATCHEM and re-simulating the column experiments showed that the modelling process is improved compared with theUNSATCHEM version containing the McNeal (1968) clay swelling model. However, the outflow and conductivity values produced were still less than measured values. This result suggested that further investigations are required to identify the effect of pH on the change of hydraulic conductivity, cation exchange capacity, and the exchangeable sodium percentage. Further research is also required regarding bicarbonate chemistry duringapplication of highly saline-sodic water.
41
He, Yangbo. "Sodic Soil Swelling and Dispersion and their Implications for Water Movement and Management". Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27543.
Testo completoAbstract (sommario):
North Dakota has over 1.9 million ha of sodium-affected soils, influencing water movement and crop production. This dissertation consists of four studies examining different aspects of sodic soils. The first study surveys sodium adsorption ratio (SAR) methods to determine which is the most reliable. The second and third studies investigate the dispersion and swelling functions of sodic soils. The final study examines field spatial distribution of Na in order to propose management strategies. Analytical approaches for converting alternative to standard approaches are needed. The SAR was determined from many non-standard techniques. One hundred soils were used, SARe and 1:5 soil/water SAR1:5 determined using shaking, stirring, and a USDA-NRCS method were compared. Three of the methods influenced the SAR1:5 values. Electrical conductivity (EC), SAR, and Ca/Mg ratios influence dispersion. Three pure clay minerals (montmorillonite, kaolinite and illite) were pretreated by variable Na and cation ratios and absorbance was determined using spectrophotometer for dispersion. Calcium-Mg ratios across the same SAR did not influence clay dispersion. Dispersion increased with higher SAR and reduced EC whereas no dispersion for kaolinite. Swelling is associated with hydration of clays, which forces clay tactoids to separate. Four soil series from North Dakota field sites were used. To assess swelling, field capacity (FC) was used as proxy. The study found that soil Na and soluble salt concentrations were two important chemical factors influencing FCW. The FCW increases with increased SAR and lower levels of EC. These results indicate that maintaining an EC level above 4 dS m-1 may mitigate swelling, which is an issue considered in tile drainage. Over- and under-application of amendments in sodic soils was studied in a 8.1 ha sodic soil field. At each site, samples were taken from two depths; electromagnetic (EM38) and elevation readings were done. Elevation was significantly correlated with soil variables except for Na%. The EM38 was reliable to express soil EC and was correlated with Na% and dispersion. Therefore, conducting the EM38 and RTK may allow site-specific management of Na. Improved knowledge of sodic soils dispersion, swelling, and field distribution will benefit researchers and farmers in managing their fields.NRCS Conservation Innovation Grant
China Scholarship Council
North Dakota Water Resources Research Institute
42
AragÃo, Ana Paula Bezerra. "Techno-economical analysis of the reclamation of a sodic soil in the Irrigated Perimeter Curu-Pentecoste-CE". Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=5281.
Testo completoAbstract (sommario):
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoNo Nordeste semi-Ãrido, as maiores incidÃncias de Ãreas salinizadas sÃo observadas nas terras intensamente cultivadas com o uso da irrigaÃÃo nos PerÃmetros Irrigados, sobretudo aqueles com o mÃtodo por superfÃcie. O experimento foi realizado no NÃcleo D do PerÃmetro Irrigado Curu-Pentecoste - CE. A pesquisa teve como objetivo avaliar o efeito da subsolagem do solo associada com tratamentos quÃmicos e biolÃgicos, na melhoria das condiÃÃes de transmissÃo de Ãgua no perfil do solo, de atributos fÃsicos e quÃmicos do solo, na produtividade do feijÃo-de-corda [Vigna unguiculata (L.) Walp.] cultivar Epace 11 alÃm dos indicadores de rentabilidade da recuperaÃÃo de um solo sÃdico irrigado por sulcos. Utilizou-se o delineamento experimental de blocos inteiramente casualizados com cinco tratamentos e cinco repetiÃÃes. Os tratamentos foram T0: testemunha; T1: 40 t.ha-1 de matÃria orgÃnica; T2: 20 t.ha-1 de gesso; T3: 20 t.ha-1 (gesso) +40 t.ha-1 (M.O); T4: 10 t.ha-1 (gesso) + 20 t.ha-1 (M.O). Os resultados permitiram as seguintes conclusÃes: 1. A produtividade do feijoeiro com o uso de melhoradores quÃmicos foi superior em 120% à produtividade sem o uso destes melhoradores e inferior em 18% à produtividade da cultura em solos sem problemas de salinidade do PerÃmetro. 2. As maiores produtividades do feijoeiro estÃo associadas a maiores profundidades do lenÃol freÃtico. O incremento de produtividade do feijoeiro com a profundidade do lenÃol freÃtico ocorreu a uma taxa crescente. 3. A aplicaÃÃo de 20 t.ha-1 de gesso e 40 t.ha-1 de matÃria orgÃnica proporcionou jà no primeiro ano, a reduÃÃo da percentagem de sÃdio trocÃvel do solo, inicialmente de um valor mÃdio superior a 50% para um valor convergente de 2%. 4. LimitaÃÃo quanto à cota de saÃda dos drenos laterais orientam para a instalaÃÃo do sistema de drenagem subterrÃnea do tipo intercepÃÃo, embora os gradientes hidrÃulicos mÃdios do movimento de Ãgua subterrÃnea sejam bem inferiores a 1%. 5. A taxa relacionada entre o valor bruto da produÃÃo gerado exclusivamente pela cultura do feijoeiro e o custo da recuperaÃÃo do solo, demonstra que a renda gerada pela cultura contribui em 12% com o custo da recuperaÃÃo do solo sÃdico. 6. O processo de recuperaÃÃo demonstra uma boa viabilidade a uma taxa de 12% ao ano e alta viabilidade a uma taxa de juros de 6% ao ano, revelando que a essa taxa todo o investimento realizado serà recuperado e remunerada e ainda um lucro extra igual a R$ 5.328,85.
In the semi-arid part of Northeastern Brazil, the highest incidences of salinized areas are observed in land subjected to intense irrigated cultivation, in the âPerÃmetros Irrigadosâ (irrigated perimeters), particularly those where is used the surface method. The experiment was performed in the âNÃcleo Dâ (D Core) of the âPerÃmetro Irrigado Curu-Pentecoste - Ceâ. The research aimed at evaluating the effect of the subsoiling of the treated area combined with the application of chemical and biological treatments in the same area. Specifically, it aimed at evaluating the effect of the said combination (a) in the improvement of the hydraulic properties in the profile of the soil, (b) in the improvement of the productivity of the cowpea [Vigna unguiculata (L.) Walp.] of the Epace 11 cultivar and (c) in the indicators of profitability of the recovery of a sodic soil irrigated by furrows. We used a randomized complete block experimental design with five treatments and five replications. The treatments were T0: control, T1: 40 t ha-1 of organic matter, T2: 20 t ha-1 gypsum T3: 20 t ha-1 (gypsum) + 40 t ha-1 (MO) T4: 10 t ha-1 (gypsum) + 20 t ha-1 (MO). The results allowed the following conclusions: 1) The grain yield with the use of chemical enhancers was 120% higher than the productivity without those enhancers and 18% lower than the productivity (of the same cultivation) in soils without salinity problems. 2) The highest bean yields are associated with the largest values of water table depth, the increase in grain yield with the depth of the water table occurring at a rate increasing with the same depth. 3) The application of 20 t ha-1 gypsum and 40 t ha-1 Organic matter, no later than in the first year, reduced the percentage of exchangeable sodium in the soil, from an initial average above 50% to a convergent value of 2%. 4) The limitation on the elevation of the outflow of lateral drains indicate the necessity of the installation of an underground drainage system of the interception type, even if the average hydraulic gradient of the of groundwater flow is well below 1%. 5) The rate between the gross value of production generated by the cowpea crop and the cost of remediation of soil, shows that the the crop contributes with 12% of the cost of soil sodium remediation . 6) The recovery process shows a good feasibility at a rate of 12% per year and high viability at a rate of interest of 6% per year, revealing that at that rate all the investment will be recovered and paid, plus yelding an extra profit of R$ 5,328.85.
43
Santos, Alex Paulus Ribeiro dos. "Efeito da irrigação com efluente de esgoto tratado, rico em sódio, em propriedades químicas e físicas de um argissolo vermelho distrófico cultivado com capim-Tifton 85". Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-27092004-165932/.
Testo completoAbstract (sommario):
A escassez natural de água doce no mundo tem sido agravada pela poluição dos cursos de água. Os sistemas de tratamento de esgotos geram resíduos, dentre eles, o efluente de esgoto tratado, que quando lançado em rios, tem causado impacto ambiental. O uso do efluente de esgoto tem sido considerado uma prática importante para minimizar os impactos negativos aos corpos dágua, sendo que o uso agrícola tem ganhado popularidade em muitos países. Além de se constituir em fonte de água para culturas agrícolas e florestais, o efluente possui elementos essenciais para a nutrição de plantas. No entanto, apesar dos benefícios concretos com o aproveitamento do efluente de esgoto tratado na agricultura, a presença de alguns constituintes como, por exemplo, o Na, pode trazer sérias restrições ao seu uso. O aumento do teor de Na no solo provocado pela irrigação com efluente pode causar toxidez para algumas culturas e modificar propriedades do solo. O presente estudo teve como objetivo verificar os possíveis efeitos da irrigação com efluente em algumas propriedades químicas e físicas de um ARGISSOLO VERMELHO Distrófico cultivado com capim-Tifton 85 no município de Lins/SP. Para atingir o objetivo citado foram realizados estudos que visaram: (i) monitorar a qualidade do efluente, da água de irrigação e da solução do solo quanto à alcalinidade, condutividade elétrica (CE), pH, razão de adsorção de sódio (RAS) e quanto às concentrações de Na, Ca, K, Mg e Al; (ii) monitorar o pH do solo, a acidez potencial (H+Al), os teores dos cátions Na, K, Ca, Mg e Al trocáveis no solo; (iii) verificar a possível ocorrência de dispersão de argilas do solo devido à adição de Na via efluente de esgoto tratado e (iv) determinar a produção de massa seca do capim-Tifton 85 irrigado com água e com efluente. A irrigação com água e efluente foi realizada durante de seis meses por um sistema de irrigação por aspersão convencional, sendo que os volumes adicionados foram determinados com base na manutenção da umidade do solo para desenvolvimento do capim que teve crescimento diferenciado entre os tratamentos. O delineamento experimental foi o de blocos completos casualizados em parcelas subdivididas no tempo, com cinco tratamentos e quatro repetições. Tanto o efluente quanto a água apresentaram altos valores de RAS, porém, os menores valores foram observados para o efluente. A acidificação do solo e da solução ocorreu após irrigação com água e efluente. O Al trocável aumentou devido a redução do pH. Tanto a água quanto o efluente ocasionaram aumento do teor de Na no solo, devido à elevada concentração desse elemento na água e no efluente. A dispersão de argilas ocorreu em toda a área e o aumento com o tempo foi mais pronunciado em superfície o que está de acordo com o maior aumento do percentual de sódio trocável (PST) e da RAS da solução do solo. O efluente foi eficiente em suprir o capim-Tifton com água, não resultando em prejuízo de acúmulo de massa seca em relação ao tratamento de irrigação com água.The natural scarcity of freshwater in the world has been aggravated by the pollution of the watercourses. The systems of treatment of sewage generate residues, such as treated sewage effluent, that when launched into rivers, has caused environmental impact. The use of the sewage effluent has been considered an important practice to minimize the negative impacts on the water supplies, and its use in agriculture has gained popularity in many countries. Besides being a water source for agricultural and forest cultures, the effluent contains essential elements for plant nutrition. However, despite the benefits of the use of treated sewage effluent in agriculture, the presence of some constituent such as Na brings restriction to its use. The level of Na in the soil may increase by means of the irrigation with effluent, and it may cause toxicity to some cultures and modify soil properties. The present study had the objective to verify the possible effects of the irrigation with effluent on some chemical and physical properties of a Typic Hapludults cultivated with Tifton 85 grass in the city of Lins/SP. The studies carried out aimed at: (i) monitoring the quality of the effluent, the irrigation water and the soil solution in relation to the alkalinity, electrical conductivity (EC), pH, sodium adsorption ratio (SAR) and in relation to the concentrations of Na, Ca, K, Mg and Al; (ii) monitoring the pH of the soil, the potential acidity (H+Al), the levels of Na, Ca, K, Mg cations and exchangeable Al in the soil; (iii) verifying the possible occurrence of clay dispersion in the soil due to addition of Na through treated sewage effluent and (iv) determining the production of dry mass of Tifton 85 grass. The irrigation with water and effluent was carried out for six months by the use of a sprinkler irrigation system, being that the added volumes had been determined on the basis of the maintenance of the humidity of the soil for the development of grass that had growth differentiated between the treatments. The experimental design was a split plot scheme of randomized blocks subdivided in time, with five treatments (A, E1, E2, E3 and E4) and four replications. Both effluent and water presented high values of SAR, however, lower values were observed for the effluent. The acidification of the soil and the solution occurred after the irrigation with water and effluent. The exchangeable Al increased due to the reduction of pH. Both water and effluent increased the level of Na in the soil, due to the high concentration of this element in the water and in the effluent. The dispersion of clay occurred in all the area, and the increase in time was higher in the surface in accordance with the highest increase of exangeable sodium percentage (ESP) and SAR of the soil solution. The effluent was efficient in supplying Tifton grass with water, not resulting in dry mass accumulation losses in relation to the treatment of irrigation with water.
44
Harris, Mark Anglin. "The effects of green manure on soil structure in calcareous sodic and non-sodic soils". 1996. http://web4.library.adelaide.edu.au/theses/09A/09ah315.pdf.
Testo completo
45
Nathan, Muhammad. "Clay movement in a saline-sodic soil toposequence". Thesis, 2001. http://hdl.handle.net/2440/109032.
Testo completoAbstract (sommario):
In the Herrmanns sub-catchment in the Mt. Lofty Ranges (near Mt. Torrens) soil sodicity was the dominant factor in causing clay to disperse in the eroded area along the foot slopes, wheras in non-eroded areas of the mid-slopes and on the stream banks, the dispersive power of sodicity was attenuated by the flocculative power of other soil properties.Thesis (M.Ag.Sc.) -- University of Adelaide, Dept. of Soil and Water, 2002
46
Grieger, Gayle. "The effect of mineralogy and exchangeable magnesium on the dispersive behaviour of weakly sodic soils". Thesis, 1999. http://hdl.handle.net/2440/19524.
Testo completo
47
Barzegar, Abdolrahman. "Structural stability and mechanical strength of salt-affected soils / by Abdolrahman Barzegar". Thesis, 1995. http://hdl.handle.net/2440/18670.
Testo completoAbstract (sommario):
Copies of author's previously published articles in pocket inside back cover.Bibliography: leaves 147-160.
xvi, 160 leaves, [6] leaves of plates : ill. ; 30 cm.
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.
Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1996
48
Chorom, Mostafa. "Behaviour of alkaline sodic soils and clays as influenced by pH and particle change / Mostafa Chorom". Thesis, 1996. http://hdl.handle.net/2440/18887.
Testo completoAbstract (sommario):
Copies of author's previously published articles inserted.Bibliography: leaves 173-196.
xviii, 197 leaves : ill. (some col.) ; 30 cm.
The objective of this thesis is to investigate the factors affecting swelling and dispersion of alkaline sodic soils containing lime and the ways to manage these soils to improve their physical condition. Studies on pure clay systems are included to understand the fundamental process involved in swelling and dispersion of pure and soil clays.
Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1996
49
Fotovat, A. "Chemistry of indigenous Zn and Cu in the soil-water system : alkaline sodic and acidic soils / by Amir Fotovat". 1997. http://hdl.handle.net/2440/19068.
Testo completoAbstract (sommario):
Copies of author's previously published articles inserted.Bibliography: leaves 195-230.
xx, 320 leaves : ill. (some col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
In this study the soil aqueous phase chemistry of Zn and Cu in alkaline sodic soils are investigated. The chemistry of trace metal ions at indigenous concentrations in alkaline sodic soils are reported. Metal ions at low concentrations are measured by the graphite furnace atomic absorption spectrometry (GFAAS) technique.
Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1998
50
Thomas, Mark. "Multiscale prediction of saline-sodic land degradation processes in two South Australian regions". 2007. http://hdl.handle.net/2440/57337.
Testo completoAbstract (sommario):
Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library.In this thesis, the distribution of saline-sodic properties forming part of a complex pattern of soils in two varied upland agricultural regions in South Asutralia were predicted at multiple scales using DSM and allied approaches.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1283986
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2007