Ozone in irrigation washes away fungal and bacterial diseases in plants – 2024-04-22 12:42:54

The use of ozone V Agriculture it’s cutting edge. Some field experiments have shown the effectiveness of foliar treatment with ozonated water in the fight against phytopathologies related to fungi and bacteria, writes the Italian publication Agronotizie after a workshop held by Ecofarm Storti entitled “Ozone in irrigation”.

The effects of adding ozone to irrigation water are still debated, although its use to disinfect irrigation system components is extremely effective.

Ozone, biocidal effect and mechanism of action

Ozone is a molecule made up of 3 oxygen atoms bonded together to form a structure with a high oxidation potential (2.07 volts), which is higher than that of chlorine (1.36 volts) and hydrogen peroxide (1, 8 volts). Ozone is therefore highly reactive. Among the products of its breakdown – note that, depending on pH, the half-life at 20 degrees Celsius is approximately 20 minutes – there are molecular oxygen and free oxygen radicals (ROS) – agents that impart strong oxidizing power.

The oxidizing effect of ROS is responsible for the biocidal and disinfecting effects of triatomic oxygen. The elimination of bacteria and fungi is determined by the effect of oxidation of the lipid component of the cell membrane. The strong oxidizing effect is manifested not only on fats (lipids), but also on all macromolecules, with subsequent changes in their structure and function. Moreover, oxidation inactivates many organic and inorganic compounds.

The disinfecting properties of ozone are used in many industrial and healthcare areas, but are also increasingly used in agriculture to treat irrigation water. Solutions that incorporate ozone into the irrigation system offer multiple benefits.

Benefits of adding ozone to an irrigation system

„ The success of using ozonated water for irrigation should be included in the logic of risk prevention” – states Giorgio Zaffani, biotechnologist at Ecofarm, during the workshop “Ozone in Irrigation”. ” Irrigation water, whether it comes from rainwater storage basins, wells or rivers, acts as a trapping agent for micro-organisms also coming from nearby crops and is often a source of crop contamination – continues the expert. From this point of view, ozone water treatment represents a very effective barrier to entry in terms of phytopathology prevention and protection.’ .

The biocidal effect of ozone added to the irrigation system also reduces the need to resort to chemical treatment of crops to control phytopathologies, with a view to sustainability.

Another advantage resulting from the use of irrigation water mixed with ozone is less maintenance on the system itself. Components—sprinklers, pipes, drip lines, and filters—sometimes become clogged due to the formation of bacterial biofilms or blockages from organic matter build-up. The strong oxidizing effect of ozone is effective in breaking down biofilm and organic matter, guaranteeing continuous efficiency of the system over time.

Unlike other chemical molecules with a disinfecting effect, such as chlorine, for example, ozone does not release residues into the environment. The main reaction product is represented by molecular oxygen. The observed effect is an increase in the oxygen content of the water.

Ozone generating machines

The workshop takes a closer look at the architecture of the ozone generator. The short half-life of the ozone molecule, composed of 3 oxygen atoms, does not allow the gas to be stored or transported, it must be generated on site.

Ozone generators are machines that convert oxygen into ozone through an endergonic reaction, i.e. one that requires energy to take place. Atmospheric air, suitably filtered and dried (dew point -50 degrees) can be used as the oxygen source to favor the reaction, avoiding the production of nitrogen oxides (NOx). To avoid such side effects, the use of a pure oxygen solution (95%) at the inlet is widespread, with the additional effect of increasing production yields.

Once the source of oxygen is determined, the reaction is performed by applying a high-voltage electric field. The two atoms of the stable oxygen molecule (O ₂ ) separate and each binds to another molecule of molecular oxygen (O 2 ), forming ozone (O ₃ ).

At this point, the produced gas is injected into the water through a venturi system, followed by a mixing process to reach the desired concentration, which varies depending on the quality of the incoming water and the flow rate of the irrigation system.

The concentrations required for effective action – indicated by Ecofarm, a company of the Storti group, producer of ozone generators for the agricultural sector – are between 700 and 900 millivolts. The unit of measurement in volts indicates the oxidation-reduction potential of ozonated water, i.e. the tendency to gain electrons or to reduce.

A feature of ozone generators is the ability to process large water flows, even up to 200 cubic meters per hour, a characteristic that makes the system suitable for large systems.

Where to place the ozone generator in the irrigation system

Usually, the ozone generator, after being applied and setting the desired concentration, works automatically. That is, the system produces ozone, injects it into the pipes and controls its amount without manual intervention. There are sensors to ensure that there is no ozone leakage from the system, potentially toxic to humans depending on the concentration.

There are various choices of ozone generators for the agricultural sector on the market, more or less customized depending on the needs. Their common feature is ease of implementation and compatibility with existing systems. Therefore, it is not necessary to redesign the irrigation system, it is simply necessary to connect the incoming and outgoing water, placing the ozone generator directly in line or inside an irrigation tank.

In the first case it is not necessary to have a storage tank, in the second the water is purified before entering the pipes, with the positive consequence of limiting the formation of biofilm and any obstructions from organic matter.

A third option is to place the ozone generator inside the tank/pond used as a source of irrigation water. Continuing in this direction, water eutrophication is prevented and dissolved oxygen levels are improved, all to the benefit of invasive species control.