Evapotraspiration - Water Management

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This section will discuss all things water management. Water alone can make or break a good playing surface and is one of our most precious resources. If managed improperly it can not only damage a playing surface but also affect all of the environment around us.

Evapotraspiration (ET) - The amount of water that is transpired from the canopy of the plant combined with the amount of water that evaporates from the soil.

I was first introduced to ET when I worked at Lahontan with Kevin Breen. All of our irrigation was based on this daily number. The goal was to look at the day's ET and replenish 90% of that number back to the soil. This way we would theoretically never have a wet spot. The dry spots were picked up by our hand watering crew, myself, and other management running overhead during the heat of the day to help reduce stress on the plant. By doing this we kept our ET rates around 0.1"-0.2" a day in the arid climate of Lake Tahoe.

Lahontan Golf Club w/Northstar Resort in the background.

 A lot factors into your daily ET. It involves what kind of grasses you are growing, what kinds of soil compositions you are working with, and how efficient your irrigation system is. Some of the small improvements that you do to your irrigation system can make a big difference in the entire system's efficiency.

Let's take a minute to break down all the possible ways your system can be inefficient.

• Worn Nozzles
• Improper nozzle selection
• Improper angle of spray coming from nozzles 
• Keep in mind a 10mph (15kph) wind will reduce efficiency by nearly 50% at best
• Improper pressure to the irrigation head
• Broken/damaged drive units in your irrigation heads
• Worn Pilot Valves causing heads to stick on 
• Sticky Foot Valves causing heads to stick on

As you can see many physical things can be wrong with your irrigation system. Each of these are small issues but when added together can cause all sorts of havoc with your playing surface.  Beyond these physical problems come the digital ones. After all, your irrigation system is controlled by a computer nowadays.