Utilização da técnica da reflectometria no domínio do tempo para medidas de condutividade elétrica aparente de um solo
Year: 2006
Type: dissertation
Abstract: Measurements of solute concentrations at soils are essential to optimize\nirrigation and fertilizer application, to study surface runoff and erosion and to\nevaluate soil salinity. For this purpose, Time Domain Reflectometry is a\ndielectric technique that has been shown to give accurate water content and\nelectrical conductivity values. Used under both laboratory and field conditions,\nthis a non-destructive essay takes simultaneous measurements of electrical\nconductivity and soil water content, using a single probe and testing only one\nsample region. Although there are many ways in which electrical conductivity\nmay be obtained with Time Domain Reflectometry equipment, few of them are\ncharacterized by simplicity and straight forwardness. Because of that, this study\naimed to evaluate different methods to determine electrical conductivity at\nsolutions and soils. A sequence of laboratory experiments was conducted in\ndeformed soil samples of an Oxisol from West Parana State, arranged in\ncolumns 0,30 m height, with an internal diameter of 0,19 m. The three â wire\nprobes, with manual assembling and without impedance-matching transformer,\nwere vertically installed in soil columns, considering as a control one the column\nwhich soil received only distilled water. The others treatments were defined\naccording to the sodium chloride content: 0,01; 0,03; 0,05; 0,07; 0,09; 0,10 and\n0,15 N. The electrical conductivity was determined using waveforms collected\nwith specific software and there wasnât signal attenuation. It was found a linear\nrelationship between the bulk electrical conductivity and the pore water\nelectrical conductivity under constant water content. It was concluded that soils\nwith significant iron contents display an atypical dielectric behavior that limits\nthe applicability of the equipment for measuring not only soil moisture but bulk\nelectrical conductivity also.
Author: Alice Leal Terres Oro
Language: Portuguese
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2787418066