What is the primary function of an ET-based irrigation controller?

What is the primary function of an ET-based irrigation controller?

• A. To run irrigation on fixed schedules only
• B. To measure soil moisture only
• C. To adjust irrigation according to evapotranspiration and plant water needs
• D. To apply fertilizer through irrigation

Answer: (C)

ET-based irrigation controllers adjust watering to what plants actually need by using evapotranspiration data. Evapotranspiration combines water loss from soil evaporation and plant transpiration. By estimating daily or periodic water demand for the specific landscape (using a reference ET value and a crop coefficient), the controller sets irrigation duration and frequency to match that demand. This means watering increases on hot, dry days and decreases when conditions are cooler or wetter, helping conserve water and keep plants healthy. It’s not simply a soil moisture sensor, and it doesn’t apply fertilizer through irrigation—fertigation is a different process. Hence, adjusting irrigation according to evapotranspiration and plant water needs is the best description.

ET-based irrigation controllers adjust watering to what plants actually need by using evapotranspiration data. Evapotranspiration combines water loss from soil evaporation and plant transpiration. By estimating daily or periodic water demand for the specific landscape (using a reference ET value and a crop coefficient), the controller sets irrigation duration and frequency to match that demand. This means watering increases on hot, dry days and decreases when conditions are cooler or wetter, helping conserve water and keep plants healthy. It’s not simply a soil moisture sensor, and it doesn’t apply fertilizer through irrigation—fertigation is a different process. Hence, adjusting irrigation according to evapotranspiration and plant water needs is the best description.