The amount of watering needed for turf is measured by which term?

• A. Evapotranspiration
• B. Humidity
• C. Rainfall
• D. Soil pH

Answer: (A)

Watering needs for turf are governed by evapotranspiration, which is the total amount of water lost from the turf area through soil evaporation and plant transpiration. This measure reflects how environmental conditions like temperature, humidity, wind, and sun drive plant water demand. In practice, irrigation is scheduled to replace the ET losses so soil moisture stays in the optimal range for turf health, often using ET0 (reference evapotranspiration) and a turf-specific coefficient to estimate actual water use (ETc). Humidity describes moisture in the air, not how much water the turf requires. Rainfall is a water input the turf receives, not the amount it demands. Soil pH has no direct relation to how much water the grass needs.