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Controlling Electrical Conductivity in Fertigation

 

Measuring conductivity is a great way to check your nutrient levels. Spot checking is great, but why not monitor and adjust automatically? In this way you can monitor multiple points in your growing operation all at once. Read on to learn more about electrical conductivity and fertigation systems.

What is EC Controlled Injection System and How is it Better?

Fertigation is one of the most efficient ways for growers to fertilize their crops because all the essential mineral nutrients are applied at their ideal concentration and in the proper balance. Fertigation is a powerful tool, but must be carefully monitored. There are two ways to check your fertigation program: electrical conductivity (EC) and foliar nutrient levels. The best way to determine if your fertilizer injector is working properly is to monitor the EC of the various fertilizer solutions and irrigation water (final mix).  

The best, most precise and efficient way to measure and maintain this vital balance is by knowing the EC (Electrical Conductivity) value of not only your incoming water supply but more importantly, your nutrified irrigation water.  In addition, direct EC measurement of the growing media and the root system is now becoming more prevalent in agriculture and hydroponics.  That being said, and agreed upon by growers and leaders in the industry; the logical question is, would it not be best to also control the injection of nutrients based on EC as well?  The answer is, of course!

Volumetric injectors can do a decent job of injecting nutrients base on waterline flow and set ratios but the actual salt concentrations are not measured directly leaving the grower to verify it later. In essence volumetric injectors are “blind” to the actual concentrations of the various fertilizers being injected.   In a way, using a volumetric injection system is like trying to analyse and control the condition of your blood by measuring your pulse.  However, with EC control the actual salt levels of the fertilizers and micronutrients are measured directly and immediately which correlates to the actual concentration of the fertilizers (nutrients). Apart from these advantages, the efficiency of injection is greatly increased, while substantially reducing costs.  The condition of the incoming water source is continuously monitored allowing for automatic adjustments in nutrient injection base on any changes that may occur.  This dynamic capability is virtually impossible for the standard volumetric injector.   Unlike flow-driven systems of the past, the HANNA Fertigation System continuously measures the actual EC and pH of the flow-through, and precisely adjusts the concentration of fertilizer into the system.   

 

The Advantages of Direct Independent Nutrient Injection

Some fertilizer concentrates (stock solutions) can interact to form insoluble compounds and precipitates. Care must be taken to ensure these concentrates remain separate.   Fertilizers containing calcium must not be mixed with fertilizers containing sulfates or phosphates while in concentrated form.  The HI10000 utilizes separate and independent nutrient injectors that completely isolate concentrates until they are introduced into the irrigation stream where they are diluted and precisely mixed. 

Ca(NO3)2 (Calcium Nitrate) + (NH4)2SO4 (Ammonium Sulfate) > CaSO4  (Precipitate of Calcium Sulfate)

When precipitates form, they tie up key nutrients and make them unavailable to the plants.  Precipitates also cause clogging of the irrigation lines and fouling of irrigation equipment.

 

No More Complicated Pump Injectors

The advantage of Venturi Injectors over volumetric pumpers…  Venturi injectors are a highly efficient way to introduce liquid or gas into water. They are ideal for dosing chemicals, aerating water, and fertigation.

Venturis work on a principle of differential pressure. Water flows into the Venturi at a higher pressure and exits at a lower pressure. This pressure differential creates a vacuum at the suction port located on the side of the injector. This suction draws liquid or air directly into the water stream. The greater the difference in pressure, the greater the vacuum and ultimately the greater the efficiency of mixing.  Unfortunately, many Venturis currently manufactured have somewhat limited application and require varying pressure differentials to meet the requirements of vast flow ranges and fertilizer application requirements.

Hanna Instruments has produced a Venturi injector specifically for Fertigation that maximizes suction and mixing without requiring massive pressure differential.  The Hanna Venturi was designed to be extremely efficient and functional over a vast flow range that is specific to the needs of Growers.

Advantages of the Hanna Venturi

  •         No moving parts
  •         Virtually no maintenance
  •         Unlimited life expectancy
  •         Injection rate as high as 1600 l/h
  •         Union fittings for quick connection
  •         Chemically resistant to all fertilizer and acids typically used in Fertigatio

 

What Else to Check?

Controlling your pH to Optimize Alkalinity

For alkalinity control, the acids commonly available to growers include phosphoric, sulfuric, nitric, and citric. The most effective and widely used acid is Sulfuric Acid; however, this is one of the most hazardous acids to use. For low amounts of alkalinity removal, Phosphoric Acid may be the acid of choice. However, care must be taken when using this acid because Phosphorus levels will increase. Nitric Acid is theoretically ideal because it adds nitrate nitrogen; but it fumes and is highly oxidizing, making it very difficult to handle. Citric Acid is a weak organic acid and a solid, making it safer than the other three; but it is much less effective, and therefore more expensive to use.   In any Facility the water flowing to your crops is inarguably the life blood of the operation.  The most important factors in the capability of your water to effectively provide nutrients to plants are pH and Alkalinity.  Hanna produces the most advance pH control and Fertigation systems on the market that will precisely adjust the pH and alkalinity of you irrigation water “in-tank” or “in-line” over a vast flow range.  

This guarantees optimal growth, maximized yields and efficient use of nutrients eliminating waste.  When properly automated with Hanna pH control and Fertigation Systems, Commercial Greenhouses, Hydroponics Operations, Grow Rooms, Living Walls, and Vertical Farming Facilities can create an environment where the nutritional uptake of the root system is always maximized.  Automating this process will create reliable precision and accuracy, reduce fertilizer and labor costs, increase crop yields and plant health, and provide a safe work environment for staff. Hanna has customizable options to equip all size operations.  HIACID is a standalone pH control system that can accommodate small and large facilities using any commercially available acid.  HI10000 can accommodate facilities with flow rates from 5 GPM to 750 GPM and the HI5000 and HI2500 are available for growers with smaller operations. This level of flexibility coupled with remote access can provide quality of life benefits to the grower and staff, allowing the entire pH and Fertigation process to be monitored and controlled from anywhere in the world.

When in doubt, measure your EC!

Let us help you in your testing needs. For assistance in choosing the best fertigation option, please contact us using one of the channels below.

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Mike Bogolawski

Written by Mike Bogolawski

Mike has been working at Hanna for over 20 years, and strives to deliver unmatched support and service. He will work with you from product selection to final installation and training. His goal is to continue to bring you the highest quality products as well as continual service and support ensuring you the best results, saving time and money. Mike can be reached at 401-744-4713 or mbogolawski@hannainst.com.

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