Every drip counts

One of the keys to proper irrigation is conducting a water distribution uniformity (DU) evaluation. It’s a simple procedure you can do yourself, and it should be done twice a year, said Tom Fernandez, extension specialist for the Michigan State University Department of Horticulture.

“Testing uniformity is important because it makes your water application more efficient,” Fernandez said. “If you aren’t providing uniform application, you’ll either overwater parts of your irrigation zone or underwater other parts of your irrigation zone.”

Fernandez and MSU extension colleague Tom Dudek recently released a factsheet (http://msue.anr.msu.edu/uploads/files/6-28FactSheet_WaterApplicationTOM.pdf) that discusses the seven steps to conduct a DU check for micro-irrigation systems.

Chris Howe, assistant general manager and cultural manager of Hortech Inc., improved his irrigation system with a different version of the DU evaluation.

“We put out Dixie cups in a grid pattern in an empty growing area and then turned the irrigation heads on for X minutes,” Howe said. “Then, we measured how much water was collected in each Dixie cup, depending on its proximity to where that water was coming out.”

That information confirmed why plants in one area of an irrigation zone were always dry or why plants in another area within the same zone would get too wet.

“That’s the challenging part about nursery irrigation,” Howe said. “The systems are very inconsistent with the amount of water they place in certain areas.”

Manual vs. automatic
Hortech uses information from the evaluation to adjust daily irrigation, which is managed by a grower. Other than a rainfall override, the nursery doesn’t rely on any automatic settings. Automated programs can save time, but they aren’t for everyone. Hortech grows about 750 different plant and container combinations. Different types of growing media add to the complexity.

“We may have 30 different types of plants and medias within the same irrigation zone,” Howe said. “So it becomes nearly impossible for an automated system to understand all the nuances involved in that one irrigation zone. It takes an experienced grower to observe those blocks and determine how much water it needs based on weather conditions we’ve experienced, the weather forecast we’re anticipating, the maturity of the crop – it becomes quite complex.”
 

— Matt McClellan