As young children, we learn plants need water. As we grow older and more experienced as growers, we learn how much water they need to thrive.
The next level of education is learning how what is in that water affects plants and their growth. Looking beyond the basics – and specifically at dissolved oxygen – at the most recent Cultivate conference were a panel of experts: Dr. Ping Yu, assistant professor and ornamental Extension specialist, University of Georgia; Kurt Becker, EVP of Commercial Products Sales & Marketing with Dramm Corporation; Andrew Van Geest, irrigation and automation specialist with Zwart Systems; and Justin Leavitt, business development manager with Moleaer.
Defined by the EPA, “Dissolved oxygen (DO) is the amount of oxygen that is present in water. Water bodies receive oxygen from the atmosphere and from aquatic plants. Running water, such as that of a swift moving stream, dissolves more oxygen than the still water of a pond or lake.”
Becker said, “Dissolved oxygen tools are easy to find and use – they take stock of the oxygen levels in your water.” And the good news is, your water source doesn’t need a lot of DO to be beneficial to plants – just more than 20 ppm.
Van Geest explained you’ll naturally see 2 to 3 ppm in wells and 8 to 10 ppm in ponds (from rain) as well as in municipal water.
To get an accurate reading, measure your DO where your water is being drawn from, even if that means a 30-foot-deep line. You have to look at your water source holistically, Becker said, as the levels of oxygen are different at different depths.
The type of irrigation, its timing and the temperature all affect DO level as well, Yu added. “The higher the temperature, the lower the DO.”
She also suggested growers water at regular intervals to cut down on fluctuations in DO.
You can add splashing to water to add oxygen to your ponds, but too much can release its oxidation reduction potential (ORP). ORP measures the ability of a body of water to cleanse itself or break down waste products accumulating in it.
“Low ORP means low quality water,” Leavitt said. He suggested getting meters for both DO and ORP. “Measure ORP and DO at the source and at the output to look for other issues.”
Van Geest noted that low DO invites pathogens to thrive; DO above 20 ppm greatly reduces them.
“This industry kills more plants with overwatering than with underwatering,” Becker said. “Having more oxygen in the water helps if too much water is used.”
Ultimately, measuring and properly using DO unlocks different opportunities, according to Leavitt.
“Water touches every part of your business. These measurements are incredibly important,” he concluded.
by Enrico Villamaino
