Plants need oxygen. That oxygen is also found in the irrigation water that the plants receive. With high temperatures, like in Europe last summer, the oxygen content in the water decreases. By adding oxygen to the irrigation water, the grower is keeping the oxygen level up to standard.
"At 0 degrees Celsius you have the maximum oxygen content. That is 14 milligrams per liter water", says Lub Kramer of Aquamar. "The more the temperature rises, the greater the decrease in the oxygen content. At 20 degrees you're only halfway with 7 milligrams. A plant needs at least 6 milligrams. The substances that you add, like fertilizers, also use oxygen. At high temperatures, the oxygen content drops quickly. It is important to maintain the level of the oxygen content at increasing temperatures."
Five liters of oxygen per minute
Aquamar recently developed the Pro-Vida, a machine that adds pure oxygen to the water through nano bubbles. Nano bubbles are minuscule air bubbles. "The bubbles do not float upwards straight away, but remain in the water, so they can be effective and can reach their goal. The pressure inside the bubble is practically the same as outside it," Lub explains. "The oxygen transfer rate is then up to 80,000 times higher and 1,200% more efficient. The machine can add 5 liters of oxygen per minute to the water. We can thus increase the oxygen content of water at 20 degrees, by 160%. The more oxygen the plant receives, the better the plant thrives."
The Pro-Vida is currently being tested at Interjensen, a lamb’s lettuce breeder in Rilland. Lub says: "Normally he’s at the 90 per cent oxygen level but now he reaches 160. It was the temperature that bothered him most. At 22 degrees the oxygen content was 6 milligrams. With the deployment of the Pro-Vida he achieves 10 to 12 milligrams.”
The Provida has been running now for two months in his greenhouse and has proved its capabilities during the hot summer months. "In the summer, it's important to keep the water as cool as possible," says Rienk. "From high temperatures you are more likely to suffer from biofilm. With this device we keep the oxygen level up to standard. We are now always certain that the water leaves the water treatment room with sufficient oxygen. So far we have been very satisfied with it."