Evapotranspiration, which includes evaporation and plant transpiration, is a major water expense in farming, especially in dry areas like Xinjiang. Researchers used eddy covariance to measure evapotranspiration in a cotton field with drip irrigation and plastic film. They found that evapotranspiration closely followed net radiation levels throughout the cotton growing season. Water needs were met except during boll opening. Daily evapotranspiration varied from 1.2 to 3.8 mm/d at different growth stages, totaling 514.3 mm for the entire season.