To Measure Is To Know

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If Plants Could Talk...About EC



Spotty Nutrition Management Leads to Unsellable Plants

In today's tough economy, greenhouse growers are under intense pressure to grow plants precisely, consistently and flawlessly – but also cost-effectively. And yet many growers still encounter plant nutrition problems that threaten their profitability. Why? Because their focus is on fixing problems instead of preventing problems. Prevention achieved through nutrition management is the key to a better business model.

Proactive Nutrition Management Can Lead to Greater Profitability

"Chlorotic" and "lack of feed" are common industry terms referring to incorrect fertilizer nutrient levels. The easiest way to measure fertilizer level is to check Electrical Conductivity (EC).

EC is the measure of total dissolved salts in a solution, the factor that influences a plant's ability to absorb water. In horticultural applications, monitoring salinity helps manage the effects of soluble salts on plant growth. EC is a meaningful indicator of water quality, soil salinity and fertilizer concentration. Therefore, knowing EC levels can help plant production and lead to more cost-effective use of plant inputs and less shrinkage. The presence of high salt levels is a sign that adjustments are needed – before damage shows up in plants.

Popular EC measurement techniques are saturated media extract (SME) and 1:2 or 1:5 dilution procedures. These involve removing substrate media samples from plants, adding water, waiting 20 to 60 minutes, and then filtering out the solids to arrive at readings as shown in the following chart:

Soluble Salt Guidelines for Greenhouse Growth Media
Using Various Media-to-Water Ratios

COMMENTS SME mS/cm 1:2 mS/cm 1:5
Very low levels. Indicates very low nutrient status. 0 - .74 0 - .25 0 - .12
Suitable range for seedlings and salt sensitive plants. .75 – 1.99 .25 - .75 .12 - .35
Desirable range for most established plants. Upper range may reduce growth of some sensitive plants. 2.00 – 3.49 .75 – 1.25 .35 - .65
Slightly higher than desirable. Loss of vigor in upper range. Okay for plants requiring high nutrients. 3.50 – 5.00 1.25 – 1.75 .65 - .90
Reduced growth and vigor. Wilting and marginal leaf burn. 5.00 – 6.00 1.75 – 2.25 .90 – 1.10
Severe salt injury symptoms with crop. 6.00+ 2.25+ 1.10+

These traditional techniques provide good results, but are time-consuming and sampled plants can be injured. That's why most growers don't bother.

Is there a better technique? One that growers can adopt? Absolutely! The good news is that EC can be measured with little time, effort or expense with the right diagnostic tool.

Instant and Accurate Direct EC Measurements with the FieldScout Direct Soil EC Probe


FAST – No need for tedious soil sampling and soil preparation techniques.
EASY – No need to collect media samples.
ACCURATE – With direct measurement technology, you can take readings right on the spot and get a truly accurate picture of a plant's growing environment.
PLANT-FRIENDLY – Growing plants are not disturbed or sacrificed via sample collection.

probe2Key features:

  • The FieldScout Direct Soil EC probe permits instant, accurate measurement of salts in soil media
  • 0 to 19.9 mS/cm (Accuracy ± 2%, resolution 0.01 mS/cm)
  • Automatic temperature compensation
  • Includes case, battery and EC calibration standard

Get results in three easy steps:

  • Step 1 – Water (because the growing medium must be moist for proper measuring).
  • Step 2 – Wait 30 minutes.
  • Step 3 – Take your measurement.
  • It's that simple!

See how the FieldScout Direct Soil EC Probe
works in our
online video!

Have questions?
Call us toll free: (800) 248-8873


"Be proactive and prevent shrinkage! Spend just 30 to 60 minutes per week assessing plant nutrition by checking EC levels, and then correct any detected problems."