EC index in coir growing medium

We know that in the soil, the growing medium has a number of indicators that affect the growth of plants and often includes common criteria such as pH, salinity (understood as factors directly related to the growth of plants). EC), acidity and nutrient content in the soil that plants can exchange and absorb. Each type of crop will require certain indexes or index correlations.

Among the indicators in the soil, or the medium, or the growing solution, you will often hear pH and EC. These are probably the 2 most important indicators.

  This is a well-treated coir product with a very low EC <0.5ms/cm.

EC is a very important indicator in growing media, especially coir. So let's find out what EC is and why it's so important.

EC is the electrical conductivity of a substance, it is an acronym for Electrical Conductivity. The EC index measures the electrical conductivity of a solution or a substance (possibly in a growing medium).

 

In solution, water used in hydroponic agriculture, in automatic irrigation or fertilization systems contains many dissolved salt molecules, it can exist as positive ions, negative ions, or cations, anions... The existence of these salt molecules in solutions (the moisture of the substrate) makes it capable of conducting electricity.

This can be understood that in solutions with a lot of salt, EC will be high, solutions with less salt, EC will be lower.

Therefore EC is an important indicator to determine the total salt content of the solution, but it does not help us to determine the ionic composition of the water. It is understandable that we can determine the EC in the substrate (or the substrate after hydration) is 0.5ms/cm, but we do not know how much Potassium (K+) or Na+ ions are present in the solution. .

There are some elements that act like fertilizers like Urea that do not increase or decrease EC. Specifically, even if the Urea content is increased, the EC index will not change.

Measuring EC
EC index in growing coir medium To measure EC, we can use a measuring pen to determine the EC index in nutrient solution, the unit of EC is mS/cm (milisiemens/cm) or μS/ cm (microsiemens/cm). Convert 1 mS/cm = 1,000 μS/cm.

Back to the growing coco peat growing medium, the lower the EC index, the better the salt treated coco peat. And readings below or above 0.5mS/cm are standard readings. For plants that require good handling of salinity, an EC value of < 0.5 mS/cm is required.

Reference:

Classification of soil salinity by conductivity (EC) (Maas and Hoffman, 1977)

Soil salt sensitivity of EC plants (dS/m) Soil salinity
Plants are very sensitive < 0.95 Very little salinity
Plants are moderately susceptible 0.95 – 1.90 Salty
Low salt tolerance 2.0 – 4.5 Moderate salinity
Moderate salinity tolerance 4.6 – 7.7 Moderate salinity
High salinity tolerance 7.8 - 12.2 High salinity
Too salty for plants > 12.2 Very salty