Which statement best describes how weather-based controls optimize irrigation efficiency?

• A. They irrigate on a fixed calendar regardless of weather.
• B. They rely only on soil moisture sensors.
• C. They require manual input daily.
• D. They use ET data and rainfall to adjust schedules for water savings.

Answer: (D)

Weather-based irrigation controls optimize efficiency by using weather information to match irrigation to what the crop actually needs. They rely on evapotranspiration (ET), which estimates how much water the crop loses to the atmosphere under current conditions (temperature, humidity, wind, solar radiation), and on rainfall data. By comparing ET-driven water demand with any rainfall and stored soil moisture, the system automatically adjusts irrigation schedules, applying water when demand is high and reducing or skipping when rain has occurred or ET is low. This targets water delivery to the plant’s real needs, reducing waste, runoff, and overwatering.

Other approaches don’t capture this adaptive, weather-driven logic: a fixed calendar ignores changing conditions; relying only on soil moisture sensors misses the broader plant water demand driven by weather; manual daily input prevents automation and responsiveness.