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Data that forecasts ET is now at your fingertips

By |  January 11, 2017 0 Comments

Wouldn’t it be nice to know the forecast ET (evapotranspiration) when making decisions about irrigation? And wouldn’t it be even better if that information were available for free and at your fingertips?

The forecast reference ET (FRET) is available nationwide free of charge on your computer at digital.weather.gov from the National Weather Service (NWS). At the web address you will reach the NWS Graphical Forecasts page. Above and to the left of the displayed U.S. map are two drop-down boxes. One is to select the geographic location of interest, and the second drop-down box is for the weather data of your choice. To find the FRET data, scroll down to Water Resources and select Daily FRET (in). After you make the selection the map will populate with predicted daily FRET.

So, when making irrigation decisions, superintendents now have data that forecasts the ET for the following day and for up to the next seven days. With this data at a superintendent’s fingertips it will be easier to provide the amount of water needed to meet the needs of the turf without overwatering.

Forecast of Reference Crop Evapotranspiration (FRET) is the expected depth of water that would evaporate and transpire from a reference crop under the forecast weather conditions on a daily and weekly basis over the next seven days. The FRET is for short crops with an approximate height of 4.7 inches, similar to full-cover grasses. Research has shown that mowed cool-season turfgrasses on an annual basis use approximately 80 percent (0.8), and mowed warm-season grasses use approximately 60 percent to 70 percent (0.6 to 0.7) of reference ET, so the forecast reference ET value presented will need to be adjusted based on the grass species on the golf course.

It’s hoped that checking daily forecast reference ET on the computer and adjusting irrigation run times accordingly will become part of the routine used when making irrigation decisions.

This is posted in Featured, Research

About the Author: Clark Throssell, Ph.D.

Clark Throssell, Ph.D., is the former director of the Purdue University turf program as well as the former director of research for GCSAA. Throssell is the research editor for Golfdom, focusing on managing the Super Science section of the magazine and website. He also contributes his "Clark Talks Turf" column to Golfdom every month.


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