Mastering Irrigation and Fertigation for Soilless Mediums

Four key factors that will take your plants above and beyond

iShence Agtech CTO & Co-founder Shelley Barak explains how to take your plants to the next level with a special emphasis on irrigation.

"Water is life," says the phrase, and rightfully so. But as modern agriculture progresses, one might argue that water precision is the key to a better life. In our case, mastering irrigation and fertigation and operating it with high accuracy will ensure better yield. This is true for any crop in a controlled environment, but the bigger challenge is when you grow in soilless mediums. The attention to water quality, timing, and volume will not be enough, and embracing a more comprehensive approach is inevitable if one wishes to reach the plants' full potential.

Growing without soil means the plants get their nutrients directly from the nutrient-rich water solution and not from the soil itself. An inert medium, such as coco fibers, perlite, rockwool, or other substrates, may physically support the roots, but the medium's only role is in operation. Without the soil functioning as a buffer, the pH of the solution and the nutrient concentration is critical for proper nutrient intake. Plant water and nutrient intake can influence the solution composition. This mandates constant monitoring and replenishment of the water to keep the right balance at all times.

The proper irrigation and fertigation plan must consider the impact of additional environmental parameters as part of the equation. Humidity, CO2, temperature, and light intensity are a few key factors we must consider under intensive indoor conditions. After performing the orchestration with high accuracy, the yield quality and quantity will gain a substantial boost.

4 Key factors for water solution optimization

As mentioned above, when growing without the soil as a buffer, it is critical to maintaining the water solution for proper water and nutrient intake. The key factors are:

1. Nutrient concentration - Nutrients are crucial for plant development. Not enough will adversely affect yield and quality, while too much will cause high osmotic pressure that will hurt the plant's ability to intake water.

2. pH - the pH level is an indicator of water acidity and is critical for nutrient intake, as shown in this image

pH level is an indicator of water acidity and is critical for nutrient intake

3. Oxygen - Plants intake oxygen via their roots, and available oxygen concentration is from both porousness in the growing medium and the oxygen dissolved in the water.

4. Water temperature - Water temperature highly affects dissolved oxygen levels, as shown in the image below

Water temperature highly affects dissolved oxygen levels

For these reasons, irrigation in a soilless medium requires replenishing the water and adjusting its qualities around the clock. Without it, the plants will not maintain optimal nutrients and will underperform. Adding any water to a dry medium will not be enough on its own.

Choosing the right irrigation system

Irrigation systems are a combination of selondis vales, large pumps for water supply, and numerous small dosing pumps injecting nutrients and adjusting pH to the water flow. They are all managed by an irrigation controller.

Choosing the correct dosing pump is a critical step in the overall design and should consider the amount of water needed and nutrient usage. There are basically two types of dosing pumps:

Mechanical Dosing Pumps

Mechanical dosing pumps (such as Dosatron and Tefam) operate using the hydraulic Venturi effect and do not need any electrical connection to run.

Their simple method of operation makes them inexpensive, but they are not very accurate, especially in low flow rates (less than 5 CMH / 3 CFM). They are also not easily adjustable if you want to change the dosing rates.

Generally, they are ideal for nutrients when growing in an open field. But if used to precisely adjust pH levels (as required when growing in soilless medium), they are inadequate.

Electrical Dosing Pumps

Electrical dosing pumps use electricity (12-24DC/110-240AC) to inject nutrients into the water solution using a motor or pulse diaphragm.

They enable higher precision and can be easily integrated into an automation system. They can control dosing rates (ml/liter or ml/gallon) per irrigation with very high accuracy.

They are also ideal for adjusting pH levels when connected to a pH probe and irrigation controller.

Although they are more expensive than simple mechanical pumps (such as Dosatron), their pricing varies according to the flow rate needed. They are an absolute must if you want to irrigate and fertigate with precision indoors.

iShence irrigation system

After countless designs and installations, we've seen time and time again there is no single solution that will fit everyone. Irrigation and fertigation systems must be modular and flexible to enable rapid deployment without compromising specific customer needs.

We use various sensors such as E.C., pH, flow meters, water temperature, water pressure, etc., and feed a constant stream of data into our machine learning algorithm to optimize and monitor the conditions. Our controller has several outputs for controlling different dosing pumps, solenoid valves, and irrigation pumps.

The setup phase is very simple and does not require special technical skills. Users can define each input/output using the iShence mobile app and create their irrigation and fertigation program in minutes.

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