Know your Conductivity – a step toward higher yield in blueberry production

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Blueberries

(Vaccinium sect.Cyanococcus)

Are one of the most famous fruit due to their health benefits and high commercial consumption. In recent years the demand for berries is growing from day to day.

The most famous varieties include:

Bluecrop

Darrow

Duke 

Eliot

Patriot

Spartan

The blueberry production is very specific as plant has a very sensible root system that requires particularly specific care in order to develop and produce fruit yield. Therefore, it is difficult to adjust all the cultivation parameters to the plant’s requirements and it is possible that some plants are destinated to failure.

Blueberry plants need a soil with specific physical and chemical characteristics to grow.

Prior to selecting appropriate blueberry sortiment, take in consideration soil quality as well as climate & geographic characteristics.

If decision is made to plant in soil, you have be sure that your soil is suitable for selected blueberry variety and that can provide chemical and physical support.

If you decide to play soiless, take in consideration to choose appropriate compacted substrate.

Chemistry is everywhere

Blueberries are one of the most sensitive options for production and require specific care in balance of chemical parameters.

Blueberries need primarily plenty of sun, air, water, and nutrients to grow. But how can you make sure your plants have enough nutrients? Measuring different aspects of soil can tell you exactly what you need and what you are missing, and help you to foster strong and healthy plants.

Testing the pH, moisture content, and temperature are a healthy start. Monitoring phosphates, nitrates, calcium, and potassium are all primary components to plant growth. Other minor nutrients are needed as well.

One way to help keep track of all these nutrients is by testing the electrical conductivity of your soil. Electrical conductivity can tell you if you need more nutrients, or if you have too much. This will save you time and money when managing your plants.

What is Electrical Conductivity?

Electrical conductivity (EC) measures how well a substance can transmit an electrical current. Small charged particles, called ions, help to carry the electrical charge through a substance. These ions can be positively or negatively charged. The more ions available, the higher the conductivity; fewer ions would result in lower conductivity. EC is typically reported in milliSiemans per centimetre (mS/cm).

In literature there is different ways to express conductivity, conversion is made as following:

1 dS/m = 1 mS/cm = 1000 μS/cm= 1 mmho/cm

Irrigation and Fertilizers

Usually, people only think of things such as the ocean as salty, but did you know soil can be salty too? These salts can be a problem if the electrical conductivity, or total dissolved solids, are too high.

Salts are very conductive and will raise the EC of your soil. Water used to irrigate crops will directly affect the quality of the soil by either increasing or diluting available salts and nutrients. This, in turn, affects the electrical conductivity.

Natural rains will dilute the amount of salt near the roots of plants. This helps to keep the plant from getting “burned” by excess salts and nutrients. This means that the plant’s roots are essentially clogged by the salts and nutrients. They become unable to take up salts, which can stunt its growth.

If irrigation water has a high salt content it can accumulate in fields, increasing the salinity and electrical conductivity. 

The addition of fertilizer is a good way to encourage crops to reach optimal growth. It is possible to have too much of a good thing, though. Fertilizers introduce nutrients and salts into the growing medium. These ions will attribute to a higher electrical conductivity. It’s important to be mindful of the electrical conductivity of your growing medium. Add too much fertilizer and you can increase the salinity and EC past safe limits.

Blueberries are highly sensitive to high conductivity value and your yield will be directly affected.

Optimal EC values to obtain for blueberries is 1 mS/cm at which you can anticipate the highest yield, after which bluberries experience a siginificant decrease in yield.

Blueberry cultivation EC (mS / cm) Yield decrease % (approx) Yield / kg (experimental example)
0.5
25
1450
1.0
10
1900
1.5
25
1250
2.0
50
1170

Soil pH & Electrical Conductivity

When soil pH and the electrical conductivity of your soil interact, interesting things happen. The pH of your soil tells you how basic or acidic it is, which can influence the electrical conductivity results.

pH is the measurement of ions as well, but specific ions. Positively charged hydrogen ions cause a substance to be more acidic, while negatively charged hydroxyl ions cause a substance to be more basic. As these ions carry charges, they can also carry electricity.

The more acidic or basic something is, the more ions there are. The more ions, the higher the electrical conductivity is. Therefore, the more acidic or basic your soil is, the higher the EC will be. The closer your pH is to being neutral, the less it will affect the electrical conductivity of your soil.

Choosing an EC Testing Method

There are several available methods of testing the electrical conductivity in production:

You can test the:

  • drip water
  • drain water (should never exceed 2.0 mS/cm, normally drain water has almost double higher EC than directly taken in supstrate)
  • pore water (the water found in the soil),
  • the total or bulk conductivity of the soil,
  • conductivity of the supstrate (or soilless media)

Hanna Tip:

When measuring EC in soil & soilless medium, take measurements right next to the plants as well as further away. Moisture, nutrients, and pH can vary greatly across a planted area. This means a little more work, but you will appreciate being able to get results that better represent your planting area.

HI98331
Direct Soil EC Tester Soil Test™

The Soil Test™ Direct Soil EC Tester – HI98331 is a rugged and reliable pocket-sized tester that offers quick and accurate readings. The Soil Test™ Direct Soil EC Tester – HI98331 features a stainless steel penetration probe for direct measurement of conductivity in soils. With a compact size, single button operation, and automatic calibration, Soil Test is an excellent choice for taking direct conductivity measurements in soil.

HI9814
pH/EC/TDS/Temp meter

HI9814 is a durable, portable pH, conductivity, total dissolved solids and temperature meter for most measurements encountered in hydroponics, aquaponics or general agriculture applications. All operations and settings, are made through only two buttons and the housing is waterproof and rated for IP67 conditions. User-selectable features include selectable TDS factors of 0.5 and 0.7 as well as auto-off after 8 minutes or 60 minutes to prolong battery life.

MONITORING – 24/7 pH&EC measurements

HI981420
Monitor for Hydroponic Nutrients Groline

The HI981420 GroLine Monitor for Hydroponic Nutrients provides around-the-clock, continuous monitoring of pH, conductivity (EC & TDS), and temperature in hydroponic nutrient solutions. Quick to setup, simple to use, this monitor was designed with Hydroponics, Aquaponics, and Greenhouses in mind. Make your nutrient solution easy to manage with the GroLine Monitor.

  • Get 24/7 pH&EC measurements for consistent yields every time.
  • Good Laboratory Practice (GLP) feature for professional accuracy.
  • Calibrate pH and EC with a single Quick Cal solution.
HI981421
Monitor for Hydroponic Nutrients GroLine 
with inline multiparameter probe   
The Monitor for Hydroponic Nutrients, HI981421 GroLine provides around-the-clock, continuous monitoring of pH, conductivity (EC & TDS), and temperature in hydroponic nutrient solutions. Quick to setup, simple to use, this monitor was designed with Hydroponics, Aquaponics, and Greenhouses in mind. Make your nutrient solution easy to manage with the GroLine Monitor.

  • Get 24/7 pH&EC measurements for consistent yields every time.
  • Good Laboratory Practice (GLP) feature for professional accuracy.
  • Calibrate pH and EC with a single Quick Cal solution.

Irrigation automatisation & control

In blueberry production it is essential to establish the frequency of watering so that the plant does not undergo root suffocation and through water stress. The blueberry plant has a very delicate root system which doesn’t tolerate high moisture very well.
If ratios of applied irrigation cycles vs. nutrients cycles are not carried correctly, huge losses in yield could occur.

With proper irrigation the quality and quantity of blueberries can be significantly enhanced.

Correct irrigation

Is not a simple process: the quantity of water must be sufficient for blueberry plants, and if not, photosynthesis and overall growth is impeded. However, if the amount of water is more than required, plant growth may become excessive, producing a tall, softer and/or damaged product.

We design and manufacture a complete, ready-to-install, ferti-irrigation system for our customers.

At first, we collect the information and requests of the agronomist to create a system that corresponds to the actual needs of the customer.  Afterward, we analyze the existing infrastructures to be able to interface our systems with the fixture already installed.

Finally, we produce the customized system and proceed with the installation, commissioning, and training of the personnel in charge.

Our ferti-irrigation systems have multiple applications:

  • Outdoor farming
  • Indoor (soil) farming
  • Hydroponics
  • Aeroponic

Our fertigation system integrates Hanna Instruments process equipment with high-quality industrial products to create two types of systems:

  • Direct injection of nutrients
  • Mixing tank

Fertigation Controller

The Fertigation Controller can control the quantity of irrigation water based on time or volume. Different sectors can be irrigated at different times during the day with different water quantities.

With the Fertigation Controller, each irrigation program provides control of pH and conductivity. When necessary, a specific program performs a pH correction by the introduction of an acid or base into the irrigation water. pH control is based on multiple sensor input and a specific set point, while conductivity control is directly related to the level of fertilization.

When the Fertigation Controller commands the addition of 1 to multiple fertilizers in the irrigation stream, conductivity sensors continually monitor the conductivity of the stream and the overall amount of fertilization is maintained based on a specified set point (limit). The Fertigation Controller can command the addition of multiple (1 to 4) fertilizers to irrigation water. The percentage of each fertilizer is set up by the user and controlled by a specific program based on the conductivity set point.

If a pH or conductivity control problem arises, the program generates an alarm to inform the user. All operations of both control processes are stored in the memory.

The Fertigation controller performs all necessary operations, monitoring, control of irrigation, and fertilization processes. These operations are conducted continuously throughout the day, month and year.

To use and manage the system properly, all the necessary control values must be set (setup mode). During monitoring operations (consulting mode) the user can obtain information about how the system and irrigation process are functioning. Furthermore, the history of all operations for the current and previous days can be accessed.