Which irrigation scheduling approach uses local weather data and plant water use to determine irrigation timing?

• A. Calendar-based scheduling
• B. ET-based irrigation scheduling
• C. Fixed-interval scheduling
• D. Soil moisture threshold scheduling

Answer: (B)

Relying on evapotranspiration-based scheduling uses local weather data and the crop’s water use to decide irrigation timing. By estimating how much water the crop loses each day through evaporation and transpiration, you match irrigation to actual plant needs. In hot, dry conditions ET rises, prompting irrigation sooner; in cooler, more humid conditions ET drops, so you can wait longer. This is different from calendar-based or fixed-interval approaches that irrigate on a set date regardless of conditions, and from soil moisture threshold scheduling that focuses on how much water remains in the soil rather than how much the plant is demanding. So, using ET-based scheduling best fits a system driven by local weather and plant water use.