Irrigation Notes - Universal Devices ISY-994i User Manual

17 Irrigation Notes

Example programs can be found in section: 11.4 Irrigation Timer Programs
17.1 Evaporation and Irrigation
17.1.1 What is Evapotranspiration
• ET is an approximation of the amount of water leaving the soil via a combination of
evaporation and transpiration (a fancy word for plants drinking it up).
• The goal of an ET-aware irrigation system is to approximately (despite all the
appearance of precision, we have to remember this) replace this water.
• It does this by tracking the water used/lost from the soil until a threshold is reached
(where the plants would starve for water if much more left without replacement).
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Figure 256: Program Condition Window
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