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What is EC?

Learn more about electrical conductivity, EC measuring and EC management

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What is EC?

Electrical conductivity or "EC" is a measure of the “total salts” concentration in the nutrient solution (drip, slab or drain).

It is expressed in milliSiemens per linear centimeter (mS/cm) or microSiemens per linear centimeter (mS/cm) where 1mS = 1000µS. The conductivity of a given solution can change with temperature for this reason most nutrient solution analysis is carried out at 20oC.

The higher the “total salts” concentration in a substrate the higher the EC. An EC will only be registered when inorganic ions are present in solution. Examples of inorganic fertiliser ions are N, P, K, Ca, Mg, etc. Urea, an organic molecule, will not contribute to the EC of a solution because it cannot conduct electricity the way a calcium (Ca) ion or a nitrate-nitrogen (NO3-N) ion can.

The required EC for optimum plant growth will depend on the crop and variety being grown the physiological stage of plant development and the prevailing environmental conditions both inside and outside the greenhouse.

Why is it important to monitor EC?

The EC of the nutrient solution influences the growth and development of the plant. During the winter months a higher EC is used as this restricts the uptake of water. As a result, the cells in the plant do not elongate or "grow" as much. They remain smaller and have a thicker, stronger cell wall. The plant then appears darker, shorter and with smaller leaves.  In this situation, the plants put relatively more energy into the formation of flowers and fruit (a generative response).  If the EC is too low in poor light conditions (i.e. winter), the plant will produce too much leaf growth and too little fruit growth and hence will be too vegetative.

Conversely, a high EC under high light conditions (summer) will restrict water absorption too much and therefore the ability of the plant to cool itself via transpiration. Consequently, the crop will become stressed.

The EC also influences production and fruit quality. In general, a higher EC in the root zone environment leads to lower production and smaller fruit size. This is because the cells in the fruits take up less water, which results in a lower fresh weight. However, a higher EC results in better fruit taste. Therefore a compromise must be struck between fruit quality, yield and the vegetative and generative development for the crop.

It is important therefore to maintain the correct delta EC within the root zone environment (measured as the difference between the slab EC and drip EC). The value for delta EC differs for each crop type and time of year. For more details please refer to the crop specific water management guidelines for the Master™ slab by clicking here.

 

 

Monitoring the EC in the slab

Monitoring EC in the slab is an essential part of weekly nutritional monitoring and should be undertaken on a daily basis. Sampling should take place in a number of representative slabs in order for a meaningful and accurate assessment to be made. Sampling is easy, simply push a syringe into the slab and extract a small quantity of nutrient solution (100 ml) and place this into the cup of the EC meter for a direct reading. Calculate the value for delta EC and plot this on a graph this will make it easier to identify trends. Alternatively the slab EC can be monitored directly over the course of the day and the results graphed automatically using GroSens. GroSens also measures and produces a graphical output of the slab water content and slab temperature. GroSens makes EC management easier. 

Tips for accurate EC measuring using a portable meter

  • Calibrate the EC meter regularly using standard solutions.
  • Check the battery status, low batteries in portable EC meters are often a cause of error.
  • Always take measurements at the same time each day this will allow easier interpretation of the result.
  • Store the meter in a cool dry place.
Learn more about GroSens

Our EC Whitepapers

Monitoring nutrient balance, pH & EC in the root zone

The nutrient solution's composition is crucial for crop growth, and Grodan's stone wool substrates offer growers total control. Stone wool does not interact with individual elements during the cultivation cycle. However, nutrient uptake varies with growth, impacting the balance, pH, and EC in the root zone. Regular analysis, combined with daily monitoring, grants complete control over crop nutrition. This precision prevents mistakes in plant and fruit quality, optimizing water and fertilizer inputs while minimizing environmental impact from drain water flushing. Grodan's approach empowers growers to fine-tune cultivation cycles for maximum efficiency and sustainability, ensuring a well-controlled and environmentally conscious crop management system.

Downlaod whitepaper

Steering and control of EC and WC in the slab under summer conditions

Achieving optimal slab Electrical Conductivity (EC) and Water Content (WC) becomes crucial as the longest day approaches in the growing season. This period is marked by heightened stress and demands on both the crop and the substrate. Maintaining the proper 'rhythm' between the slab and the crop is essential for maximizing production and ensuring high fruit quality.

As the crop reaches its peak fruit load, the focus shifts to preserving fruit quality and ensuring the crop's survival through the challenging summer months and into autumn. The emphasis on these aspects is particularly crucial during this stressful phase of the growing cycle. The overarching goal is to create an environment that supports the crop's well-being and productivity.

To optimize slab EC and WC, growers must carefully manage the nutrient levels and moisture content in the substrate. The slab's electrical conductivity is a measure of the nutrient concentration, and it needs to be adjusted to meet the specific requirements of the crop at this stage. Precise control of the water content is equally important, as the crop's demand for water fluctuates during this critical period.

Striking the right balance in EC and WC ensures that the crop receives the appropriate nutrition while maintaining an optimal water supply. This balance is instrumental in sustaining the crop's health and productivity, especially when facing the challenges associated with the prolonged daylight hours and increased environmental stress.

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Making informed decisions in respect to water and EC management

This article emphasizes the strategic approach to root zone steering within a 24-hour period following the 6 Phase model. It underscores the importance of a substrate adaptable to irrigation session length. While the provided tables offer examples, the article stresses the need to generate standardized graphics from the GroSens system and climate computer, incorporating WC and EC alongside radiation metrics. Correctly scaling these graphics is crucial for detailed insights. Examining the graphic over shorter periods reveals specific details, while analyzing trends requires a broader focus over 7 or 10 days. Ultimately, these graphics offer essential management information to inform decisions, ensuring an effective and well-informed root zone steering strategy. When reading the graphic look for the key triggers in the decision making process should changes be required:

  • What was the light sum at irrigation start time? 
  • At what light intensity was drain realised? 
  • Was EC lowest when radiation intensity was highest? 
  • What was the light intensity when the last irrigation was given? 
  • How many joules remained until sunset? 
  • What was the decrease in WC overnight?

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Steering WC & EC at the start of the cultivation

Effective root management is crucial from the onset of cultivation. Cutting drain holes may seem mundane, but their accuracy is irreversible; thus, precision is paramount. Developing a comprehensive plan early on, including understanding the optimal water content (WC%) and electrical conductivity (EC) limits for your chosen slab type and crop, empowers informed decisions during the cultivation's steering phase. This proactive approach ensures that root development is optimized, contributing to healthier plants and higher yields. By recognizing the significance of these foundational tasks and adhering to best practices, growers can lay a solid groundwork for successful cultivation outcomes.

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Learn more about EC management

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EC – important parameter for irrigation strategy

The electrical conductivity (EC) unit is commonly employed for analyzing fertilizer component concentrations in hydroponic growth’s nutrient solution or root zone. This involves measuring the electrical conductivity of a solution to determine the cumulative ions necessary for plants (e.g., NO3-, Fe3+) and ballast components (e.g., Na+). The EC value is usually expressed in either millisimens (mS/cm) or microsimens (µS/cm).

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To avoid common fruit quality issues such as BER in tomato and pepper it is important to have EC under control in time and stable between days.

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Effect of early stop time and gift/radiation on EC behaviour

Grodan advises on maintaining stable substrate EC as light levels and temperatures increase, ensuring optimal crop growth.

We are a global leader in the supply of innovative stone wool substrate solutions for the professional horticultural based on Precision Growing principles.

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