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Estimation of Soil Solution Electrical Conductivity from Bulk Soil Electrical Conductivity in Sandy Soils
Author(s) -
Amente G.,
Baker John M.,
Reece Clive F.
Publication year - 2000
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2000.6461931x
Subject(s) - soil science , tortuosity , reflectometry , soil water , hydraulic conductivity , electrical resistivity and conductivity , environmental science , diffusion , power function , pedotransfer function , porosity , materials science , mathematics , time domain , thermodynamics , geotechnical engineering , geology , physics , quantum mechanics , computer science , computer vision , mathematical analysis
Studies of solute transport through soil and attendant environmental impacts are hampered by the lack of methods for continuous monitoring of solute concentration. Measurement of bulk soil electrical conductivity (EC b ) using time domain reflectometry (TDR) is a promising technique, but it is indirect, and estimation of solute concentration from such measurements requires a model relating soil solution electrical conductivity (EC w ) to EC b Several models of varying complexity exist, but further testing is required to determine their relative merits and applicability. This study was conducted to determine the efficiency of various models that use different methods of estimating the tortuosity factor, F g , in order to estimate EC w from EC b All models assume that the ratio of EC b /EC w is proportional to soil water content, θ, with F g as the coefficient of proportionality. In this study, two types of models were compared, those in which F g is obtained from soil hydraulic properties and those in which F g is estimated as it is in gas diffusion models, except with θ rather than porosity as the independent variable. Measurements were conducted in a sandy soil, across a range of EC w from 0.10 to 0.56 S m −1 The models in which F g is obtained from soil hydraulic properties did not perform as expected. The results with the gas diffusion analog models were variable; the most successful of these was based on the 1959 model of Marshall, in which F g is a power function of θ, θ b Optimal results were obtained withb = 0.58, not far from Marshall's suggested value of 0.5 for gas diffusion. We conclude that there is no benefit to the use of soil hydraulic properties in estimating EC w from EC b measurements, at least for sandy soils, where simpler relationships appear to provide superior results.