What is ET?

ET is the acronym for evapotranspiration or the sum of water evaporation from the soil and water transpiration through plants. Golf course superintendents use local weather estimates of ET or weather stations on their course to estimate ET each day. The key weather measurements needed to determine ET are solar radiation, air temperature, wind speed, and humidity. When a determined level of ET has occurred over several days, usually measured in inches, the decision is made to replace a fraction of the recorded ET with the irrigation system.