Does somebody know why in Cropwat 8.0, in the section Crop water requirements, the column : Irrigation requirements doesn't always correspond to the difference between the column ETc and the column Effective Rianfall?
There is an online study which explains the difference and how the values need to be interpreted. The study refers exactly to the irrigation requirements and its parameters. You can visit the official website of the application to read this study and understand the difference.
