Influence of substrate type and properties on root electrical capacitance
Imre Cseresnyés 1  
,   Eszter Vozáry 2  
,   Sándor Kabos 3  
,   Kálmán Rajkai 1  
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Department of Soil Physics and Water Management, Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences, H-1022 Budapest, Herman Ottó út 15, Hungary
Department of Physics and Control, Szent István University, H-1118 Budapest, Somlói út 14-16, Hungary
Department of Statistics, Eötvös Loránd University, H-1117 Budapest, Pázmány Péter stny. 1/A, Hungary
Imre Cseresnyés   

Department of Soil Physics and Water Management, Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15., H-1022, Budapest, Hungary
Final revision date: 2019-07-26
Acceptance date: 2019-09-05
Publication date: 2020-01-15
Int. Agrophys. 2020, 34(1): 95–101
Three pot experiments were performed on cucumber, maize, soybean and wheat plants to investigate the effects of various substrate types, namely pumice, arenosol and chernozem soil (Exp. 1), of substrate salinity (Exp. 2) and of soil water content (SWC; Exp. 3) on the electrical capacitance measured in root-soil systems. The data were evaluated according to the basic principle of the two-dielectric capacitor model. Statistical analysis indicated that the capacitance measured in root-soil systems was determined by the capacitance of the root system for each combination of plant species and substrate. Furthermore, the results showed that substrate impedance had a negligible influence on the capacitance measured in root-soil systems. Substrate salinity had no direct effect on capacitance measured in root-soil systems, but salt-induced physicochemical changes in plant tissues could have influenced its dielectric properties. Capacitance measured in root-soil systems increased exponentially with soil water content (it ranged from 10 to 48 v/v %), indicating that the measured capacitance was more sensitive to variability in moisture content at high rather than at low water saturation levels. This is not consistent with the general consensus that the capacitance method is unreliable in dry soil and should be used at soil water content close to field capacity. The present results will contribute to the more effective application of the root capacitance technique
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