4
Electrical conductivity (EC) is an important
parameter in evaluating irrigation water and fertilizer
solutions. Crops can be damaged if irrigated with
water with a high conductivity. The quality of
irrigation water has been classified into 5 separate
categories (See Appendix 2, p. 19). EC is also an
indicator of the strength of fertilizer solutions. In
greenhouse applications and other situations
requiring frequent fertilization, EC should be checked
regularly to ensure the plants are getting sufficient
nutrients while avoiding the effects of salt toxicity.
See Appendix 1 (p. 18) for a list of preferred EC
values for some common plants. Typically, younger
plants will require lower EC than mature plants.
The stainless steel soil EC probe is designed to be
inserted directly into soil. The sensing surface is
composed of 2 pairs of electrodes on the probe tip.
Additionally, the probe is narrow in diameter so it can
be used effectively in plug trays.
Because EC readings are affected by moisture
content, it is important that soil moisture content
does not differ significantly between readings. An
easy way to achieve this condition is by taking
measurements approximately 30 to 60 minutes after
an irrigation. This should ensure the soil moisture
level has approximately reached field capacity.
The probe should be inserted in the root zone. The
measurement region is at the tip of the probe. For
turf, the root zone is approximately
2”
-
4”.
For
vegetables and small plants, this is about
8”
-
12”.
EC Probe
