However, using this indicator alone for irrigation scheduling is not recommended if a maximum yield is desired. This indicator is inferior for modern agriculture due to the inability to determine the actual crop water use. However, ignoring it at the critical growth stages may lead to yield reduction. Using the growth stage as a field indicator in irrigation scheduling should be coupled with more sensitive and accurate methods of determining the crop water use such as soil moisture measurements and ET data. The main advantage of this indicator is to provide direct and visual feedback from the crop.
Different Crops have different water requirements and respond differently to water stress.
Crop sensitivity to water stress varies from one growth stage to another. Table 1 is a summary of critical growth stages during which major Crops in Colorado are especially sensitive to water stress. A good irrigation scheduling scheme should consider sensitivity of the crop to water stress at different growth stages. The goal of any irrigation scheduling scheme is to keep the water content in the root zone above this allowable depletion level. This ensures that the crop will not suffer from water stress and will produce maximum potential yield.