Abstract
The effect of electrical conductivity (EC) on the voltage response of ECH2O soil moisture probe (ECH2O probe) has been investigated by laboratory experiments in salt solutions and saline as well as non-saline soils. The output of the probe decreases noticeably with increasing EC up to 0.24 dS m-1 but increases significantly over higher EC in salt solution and saline soils. However, the effect of soil-water EC is relatively small below 0.5 dS m-1 and may be neglected for practical purposes without significant error. Due to higher probe output in coarse textured soils than in fine textured soils for any particular water content, the salinity effect is much higher in sand than in clay. The calibration function between the volumetric soil-water content and probe output for non-saline soils estimates significantly different soil-water contents for soil-water EC>0.5 dS m-1. Due to less contact of dry soil with the probe and reduced width of electromagnetic field on the probe in wet soils, the ECH2O probe is less sensitive both at low and high soil-water content irrespective of the salinity level.
