Automatic Irrigation Systems

Home Grown  by Keith Reed
Summer is here! Since irrigation is such a critical issue to properly managing an Oklahoma landscape, automatic irrigation systems can be marvelous things. A properly designed and well maintained system can be a very beneficial tool. When used correctly, they will even save water versus irrigating the same area with hose and sprinkler. Include drip irrigation as a part of that system and your efficiency will increase even more.

Three major issues limit the value of irrigation systems. Poor design, lack of maintenance, and improper controller operation. Poor design and lack of maintenance are significant problems and are beyond the scope of this newspaper article. Controller operation, although intimidating to some, is a little more straight-forward. It also happens to be where the greatest difference in long term plant health and water savings can be seen. Today we’ll talk about the two most common problems, “water everything every day” and “set it and forget it”.

For purposes of this discussion, we will talk in generalities and averages. There are exceptions to almost every rule, and landscape irrigation certainly has its share. For the most part, your landscape should not require daily irrigation. Mature turf should be able to get by on two (or three at the most) irrigations a week. Mature perennials and woody plants should do fine on one or two irrigations a week.

Many soils in Payne County are notoriously tight and receive water slowly. A common complaint is “my water will just run off” if I try to put enough on to last three days. In this case, a water/soak/water cycle is needed. Water for a period, allow the water to soak in, and repeat. This would still be considered one irrigation. Most modern controllers have this option built in but it may be disguised as “multiple start times”.

As you know, water needs for our plants vary wildly from week to week. If we get adequate rain, do not irrigate. Your controller has an internal memory and turning it off should not have any effect on your programming. If it does not have this feature, consider upgrading to a better unit. Of course, there is always the issue of remembering to turn it back on. Sorry, but I don’t have any advice on this; you will have to work that out your own. Another option is to install a rain sensor unit.

This simple device detects rainfall and automatically turns the controller off for a pre-determined number of days. These units are inexpensive and easy to install. It will also be necessary to adjust the watering time as temperatures rise throughout the summer. This can be done by changing run times on individual stations. Admittedly, this can be tedious and sometimes confusing. Another option is to use the “water budget” or “seasonal adjust” feature. This allows you to vary your run time based on a percentage. For example, if you have a zone set to run 30 minutes in May, it may need to run for 60 minutes in August. The water budget feature would allow you to double all your run times by simply adjusting from 100% to 200%. Conversely, as fall approaches and the weather begins to cool, you can adjust down as the water needs change.

It is my hope that this article will encourage you to become comfortable in managing your irrigation system. If it all seems a little too mystifying and you need more information, or if you would be interested in attending a workshop on the subject, please contact Keith in the Extension Office. Look for an article soon talking about drip irrigation in greater detail.

Keith Reed is the Horticulture Educator in the Payne County OSU Extension office. You can contact him via email at keith.reed@okstate.edu, call 405-747-8320, or stop by the office at 315 W. 6th in Stillwater.

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