Introduction
Congratulations on the purchase of your FieldScout Direct Soil EC Meter. This instrument has been
specifically designed for direct measurement of salts in
soil media as well as water or nutrient solutions. This manual describes how to use your meter and keep it
working accurately for many years. Please read it thoroughly to get effective performance from your
meter. The salinity of the soil solution, irrigation water or fertilizer solution is an important parameter
affecting the root zone environment. Any of these factors can have a significant effect on plant growth
and physiology. The easiest way to monitor salinity is by measuring the electrical conductivity (EC). EC
is strongly correlated to the salinity of the soil solution. EC measurement is also affected by temperature
and, to a lesser degree, by soil moisture content.
Use this portable EC meter and probe to measure salinity in greenhouse soil media right on the spot
without tedious soil sampling and preparation. Greenhouse production managers can compare readings
from plant to plant and fine-tune their fertility program
because measurements can be made directly in a plug tray cell without cannibalizing the seedlings. Turf
managers can monitor for high salt levels on golf course greens and determine when to flush (leach) salts
before turf quality declines. The meter comes with the Field Scout Soil/Water EC probe. This single,
stainless steel probe has a specially
designed conical tip. It can measure liquid EC (water or nutrient solutions) or in-situ soil salinity. The
probe automatically compensates for temperature.
EC Probe
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 3, p. 21). 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 2 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”. Wait until the meter reading stabilizes before withdrawing the probe. Taking
several measurements will allow a representative average to be computed.
Important: Do not touch the sensor tip with your fingers. The oils on the skin will affect
the probe’s measurement accuracy.
