EQ2-UM-1.3
Page
4
Installation
The
Equitensiometer
should be thoroughly wetted before use, and installed at a horizontal
or slanting angle. Vertical installation may slow the response time, and also lead to
incorrect readings because rainfall running down the side of the probe housing may wet the
soil around the probe excessively. This is particularly important if the probe is being
installed below the soil surface using a probe extension tube. Any gaps between the
Equitensiometer
and soil should be filled with quartz powder suspension. Small changes
to the soil structure surrounding the probe will not affect readings.
It is important to protect the
Equitensiometer
from strong temperature fluctuations and in
particular to avoid exposing the electronics and equilibrium body to different temperatures,
e.g. by installing it with the case in strong sunlight. Avoid flexing the PVC cable at low
temperatures. It is advisable to protect the cable before burying it in conditions where it
may be attacked by soil insects etc.
Soil sampling points
The soil matric potential within a region of soil will be affected by local variations in soil
density and composition, rates of percolation, runoff, evaporation and the uptake of water
by nearby roots. The resultant differences in pressure will equilibrate over time at a rate
which is determined by the local hydraulic conductivity.
It is important to take the degree of variability of these various parameters into account
when deciding on the number of probes to use at any particular location. In particular, if
the soil is known to be very heterogeneous, or the distribution of roots is very non-uniform,
it will be necessary to take measurements from at least three closely-spaced locations.
Extension tubes
Optional extension tubes can be fitted to enable easier withdrawal, and to protect the cable
from damage by animals, etc. Two lengths are available. ML/EX50 is 50cms long and
ML/EX100 is 100cms long. These can be screwed into each other to make longer lengths,
as required. The outside diameter of the extension tubes is 4cms, so an auger of
approximately 5cms is recommended.
Instructions for adding extension tubes:
Carefully remove the black plastic, thread protection cover from the
Equitensiometer
. This
cover protects the extension tube mating thread when extension tubes are not needed. It can
be removed by sliding it up the cable.
Pass the
Equitensiometer
cable through the hole in the extension tube, ensuring that the
female thread in the extension tube is towards
Equitensiometer
. Screw the extension tube
onto
Equitensiometer
and hand tighten only. Repeat this process for additional extension
tubes to make up the length required.
Finally, thread the cable through the black plastic thread protection cover and slide the
cover into place over the male thread on the end of the extension tube. This will minimise
water ingress into the extension tube.
Frost
The
Equitensiometer
will withstand frosts, but any readings taken when the water inside
the probe is frozen will be meaningless.
