There is provided a method of planning irrigation, comprising: performing for a certain interval of time: computing a value of a crop evapotranspiration parameter indicative of an amount of water consumed by a reference crop, computing a value of a potential evapotranspiration parameter indicative of weather conditions associated with the field of the reference crop, computing a value of a dynamic crop coefficient for the reference crop based on the crop evapotranspiration parameter and the potential evapotranspiration parameter, and providing the dynamic crop coefficient computed for the certain time interval of time of the reference crop that corresponds to a target time interval of a target growing season of the target crop, wherein the target crop is growing in a target field which is geographically distinct from the reference field, and outputting instructions for irrigation of the target crop according to an irrigation plan based on the dynamic crop coefficient.
