Abstract
ECH2O 5TE is an useful dielectric soil mois-ture sensor for a field soil. However, it is reported that the sensor outputs are affected by the electrical conductivity (EC) of the soil and the soil temperature (T). The objec-tive of this study was to evaluate effects of the EC and T on the sensor outputs based on a laboratory EC calibra-tion and a temperature calibration according to field data measured in a sand dune field. Result of the laboratory ex-periment showed that a single calibration equation could be adapted to the data for the soil water EC (ECw) < 10 dS m−1 with the soil bulk EC (ECb) < 0.50 dS m−1. As-suming a linear relation between the sensor output change(ΔRAW) and the temperature change (ΔT) under a constant soil moisture condition as α = ΔRAW/ΔT, α values were estimated based on the field data. Whereas estimated αwas 0.8 ◦C−1 ∼ 1.2 ◦C−1 for ECw ∼ 0.1 dS m−1, it signifi-cantly increased from 1.0 ◦C−1 to 2.2 ◦C−1 for ECw > 2.5 dS m−1.
