Dr. Grady Miller
Dr. Grady Miller

Q&A with Dr. Grady Miller: Irrigation Management

Q: I am looking at ways to better manage irrigation on our baseball field. We hand water the clay, but I want to refine how we schedule irrigation for the turf area. What are some of our options? 

A: This is a great question with lots of options for you to consider. I will only have space to scratch the surface, so you will probably want to consult with irrigation vendors and equipment experts to get more specific information and pricing on some of the options I will mention.

There are three major components to irrigation management – monitoring, irrigation control, and water delivery. These three components can also be further broken down. For example, monitoring may be evaluating turfgrass stress indicators, soil moisture levels, and/or weather conditions. 

Turfgrass stress indicators will often show up in response to soil drying, and provide a visual queue that the turfgrass needs to be irrigated. The indicator will be wilting turfgrass, commonly seen as folded or curled leaves or a bluish-green-color turf. There are often specific locations on each field that show early signs of moisture stress. These areas can be used as indicators that the larger area of the field needs to be irrigated. Research is currently evaluating cameras and sensors to detect stress before it is visible, but this technology is mostly experimental. So, at this point, it is not useful for automation of scheduling irrigation.

Soil moisture monitoring may be accomplished using static, in-ground soil moisture sensors or by using portable sensors. The in-ground sensors may be linked back to your irrigation system controller for automation, and most can be monitored remotely with a smart phone. The most common portable soil moisture sensors use TDR (time domain reflectometry) for quick and accurate measurements with minimal soil disturbance. They are a bit expensive, but for site-specific monitoring they are hard to beat. Some portable instruments have the option to collect geo-referenced data to allow mapping and monitoring over time.

Weather condition monitoring may be used for short-term irrigation adjustment or for predictive modeling of water needs. Many of today’s irrigation controllers employ weather-monitoring devices and scaled-down prediction models to automatically adjust irrigation controller runtimes based on current weather conditions and plant water demands. These are known as ET (evapotranspiration) controllers.

An irrigation controller that can use information from a soil or weather sensor, and automatically make adjustments, is known as a “smart controller.” All irrigation manufacturers have some type of smart irrigation technology in their product line. The newest systems designed around smart technology offer amazing control and monitoring, but older controllers can often be retrofitted to take advantage of sensor technology. Vendors will usually provide the expertise to set up their systems to maximize functionality.

Water delivery is the application rate and distribution uniformity of the water by your irrigation system. These two values are normally measured with an irrigation audit. They are important because they help you to schedule irrigation runtimes and ensure adequate water coverage of the area. If you want to conduct you own audits, there are several extension publications available online to lead you through the process. An audit is a great place to start in your quest to refine your irrigation scheduling, because it can reveal needed component repairs and adjustments while providing data to refine zone runtimes and compensate for poor coverage.

Along with the technologies mentioned, there are several best irrigation strategies that you should review. These are listed in BMP documents available from the STMA. By introducing new technology and initiating a few new strategies, you can have quality turfgrass with minimum water use. And since most of the new technology is automated, it may give you more time to concentrate on other things.

Grady Miller, Ph.D.

Professor and Extension Turf Specialist

North Carolina State University

Send them to Grady Miller at North Carolina State University, Box 7620, Raleigh, NC 27695-7620, or e-mail grady_miller@ncsu.edu

Or, send your question to Pamela Sherratt at 202 Kottman Hall, 2001 Coffey Road, Columbus, OH  43210 or sherratt.1@osu.edu