11
SME Measurement
Saturated Media Extract (SME) Measurements
Growth media used in most greenhouse operations
is high in organic material and processed materials
and low in mineral soil. These materials are easier to
handle, are well aerated and have good moisture
-
holding properties, but have limited ability to retain
nutrients. Therefore, tests developed for field soils do
not always yield meaningful results. Saturated Media
Extract (SME) analysis has been shown to eliminate
these problems. The samples should not be dried,
sieved or pulverized as this will affect the growth
medium
properties
and
alter
the
results.
Traditionally, the soil solution from the saturated
medium is extracted by a vacuum pump. However,
the Field Scout Soil & Water EC Meter allows the
saturated sample to be tested directly.
Procedure
-
Moisten the media sample with distilled water to
reach a consistent
“
saturated
”
moisture level.
When saturated, the media should glisten and
slide from the mixing spatula with little or no free
water.
-
Wait 15 minutes and add more water if needed.
The sample should have the consistency of a
paste with slightly more water than if the media
was in a pot and fully irrigated.
-
Power up the meter.
-
Insert the probe tip into the media and read the
results.
