Many indicators have been developed to determine when and how much to irrigate to improve the irrigation efficiency. The relative available soil water (RASW) is an indicator that can be easily calculated but takes the availability of soil water to crops equally throughout the root zone profile...

Plant water stress is linked to both above- and below-surface parameters; with above-surface parameters being generally easier to measure. Models utilizing above-surface parameters, such as canopy temperature to identify plant water stress, frequently employ the crop water stress index (CWSI)....