ontario sugar beet growers - Atrium - University of Guelph

Capacitance Probes (C-Probes) were installed on June 10,2005 by the Ontario Weather
Network team in the second replicate block in each of the three irrigation regimes. Figs. 2
and 3.
Fig. 2. Installation of a C-Probe showing the two top soil
moisture sensor rings with probe being inserted into a PVC
access tube.
Fig. 3. Location of C-probe connected to Adcon telemetry
device.
A Capacitance Probe (C-Probe)
A C-Probe is a soil moisture-monitoring device that records volumetric soil moisture. The
probes (Model C-probe, Agrilink Holdings Pty Ltd., Australia) are based on frequency
domain reflectometry which takes advantage of the fact that soil electrical capacitance is
highly dependent on soil water content. The C-probes communicate with the logger via
hi-resolution analog signals, allowing a maximum of 6 sensors, (we used 5 sensors at 10,
30,50,70 and 100 cm depths), to be attached to a probe in a single soil profile. The
sensorlprobe combination (shown in Fig. 2) is inserted into a PVC tube inserted into the
soil and the probe performs a measurement whenever requested by the Adcon datalogger
system Fig. 3 (we recorded every 15 minutes). The Ontario Weather Network (OWN)
weather stations used Adcon Telemetry, GmbH radios, which transmit data to a local base
station where the sensor data is logged. The OWN calls into the station and collects the
data where it is plotted and analyzed.
Assessments were taken by rating the early seedling growth of each inbred on June 23
recording the degree of drought spiking, with 0 indicating the plant showed spiking
symptoms, Fig. 4, while a 10 indicated the seedling was not visually effected by the
drought and looked normal, Fig. 5. On the same assessment date the colour of the
seedling foliage was recorded, whether it was a normal green colour, given a rating of 5
with seed corn that had turned yellow a rating of 1 and seedlings turning purple a rating