Abstract:
Electrical conductivity (EC) measurements are often used
to identify and address soil salinity issues in irrigated cropping
systems. In this study, measurements of soil solution
EC (EC-sol) collected in ceramic suction cups (SCs), wetting
front EC (EC-wf) collected in Fullstop wetting front
detectors (WFDs) and soil bulk EC (EC-bulk) measurements
made using ECH2O-TE sensors and converted to
EC-sol, were compared. As a result of different methods of
measurement and different components of soil waterflow
being sampled, variations in EC measurement between
SCs and WFDs were observed. EC-sol was usually higher
than EC-wf, as expected for this system, due to incomplete
mixing between the draining and resident soil water during
infiltration. For periods of high solute leaching, however,
the opposite can occur, indicating that WFDs are sampling
when solutes are first mobilised at the beginning of the
leaching event. The ECH2O-TE sensors were less effective
in measuring the short-term EC dynamics but were
able to detect general changes in soil salinity. This could
reflect difficulties estimating soil EC-sol from measured
EC-bulk, especially at low soil water contents. Each of
these instruments show good potential for application to
guide salinity management practices, but a more detailed
study on a range of soils subjected to different watering
regimes is needed to further improve interpretation of EC
measurements and their application.
