Benefits of maintaining the optimum substrate oxygen level
Low oxygen levels in the growing substrate can play havoc with the health of both vegetable and ornamental plants. Shalin Khosla, greenhouse vegetable specialist at Ontario Ministry of Agriculture, Food and Rural Affairs in Harrow, Ontario, said a substrate oxygen level below 5 parts per million can have a negative effect on plant growth.
“Below 5 ppm oxygen, plants are going to suffer and at 2 ppm the roots are going to die off,” Khosla said. “The optimum substrate oxygen level is 6-8 ppm. If the oxygen level can be increased to 10 ppm is even better.”
Khosla said the temperature of the water can affect the level of oxygen.
“As irrigation water warms up it holds less oxygen,” he said. “Cold water holds more oxygen. Between 6-8 ppm of oxygen is the normal level at a water temperature of 68ºF-77ºF (20ºC-25ºC). As the water warms up to between 82ºF-86ºF (28ºC-30ºC), the oxygen level can drop to 5 ppm or lower because the plant roots are taking up some of the oxygen. Summer tap water, which is usually warmer, will have less oxygen in it.”
Read more at Hort Americas (David Kuack)