title: Determination of soil pore water salinity using an FDR sensor working at various frequencies up to 500 MHz.
abstract: This paper presents the application of a frequency-domain reflectometry (FDR) sensor designed for soil salinity assessment of sandy mineral soils in a wide range of soil moisture and bulk electrical conductivity, through the determination of soil complex dielectric permittivity spectra in the frequency range 10-500 MHz. The real part of dielectric permittivity was assessed from the 380-440 MHz, while the bulk electrical conductivity was calculated from the 165-325 MHz range. The FDR technique allows determination of bulk electrical conductivity from the imaginary part of the complex dielectric permittivity, without disregarding the dielectric losses. The soil salinity status was determined using the salinity index, defined as a partial derivative of the soil bulk electrical conductivity with respect to the real part of the soil complex dielectric permittivity. The salinity index method enables determining the soil water electrical conductivity value. For the five sandy mineral soils that have been tested, the relationship between bulk electrical conductivity and the real part of dielectric permittivity is essentially linear. As a result, the salinity index method applied for FDR measurements may be adapted to field use after examination of loam and clayey soils.
authors.affiliation: Institute of Agrophysics, Polish Academy of Sciences, ul. Doświadczalna 4, 20-290 Lublin, Poland. a.wilczek@ipan.lublin.pl
authors.forename: Andrzej
authors.initials: A
authors.lastname: Wilczek
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Szypłowska
authors.forename: Wojciech
authors.initials: W
authors.lastname: Skierucha
authors.forename: Jolanta
authors.initials: J
authors.lastname: Cieśla
authors.forename: Viliam
authors.initials: V
authors.lastname: Pichler
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Janik
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods*; D058266:Dielectric Spectroscopy; D004553:Electric Conductivity; D004784:Environmental Monitoring; D016014:Linear Models; D011189:Potassium Chloride / Q000737:chemistry; D054712:Salinity; D012987:Soil / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D012987:Soil; D014867:Water; D011189:Potassium Chloride
keywords: complex dielectric permittivity; dielectric spectroscopy; frequency-domain reflectometry; salinity index approach; soil salinity; soil water content