Which statement best describes evapotranspiration (ET) in irrigation management?

• A. ET is the combination of water loss from soil by evaporation and plant transpiration.
• B. ET is the rate of rainfall absorption
• C. ET measures soil salinity
• D. ET is the rate of water runoff

Answer: (A)

Evapotranspiration is the total water loss from a cropped area through both evaporation from the soil surface and transpiration from the plant canopy. This combined loss is what irrigation management aims to replace to meet crop water needs, making it the best description of ET. Weather factors like temperature, humidity, and solar radiation drive ET, while the type of crop and its growth stage determine how much water is transpired. The other ideas describe different processes—rainfall absorption is about how water enters the soil, soil salinity measures salt content, and runoff is water that drains away rather than the water lost to the atmosphere. So, the statement that ET equals the sum of soil evaporation and plant transpiration best captures its role in irrigation planning.