Abstract: Device and agricultural device, and operation method thereof, for measuring plant water present in vegetation comprising: an microwave emitter of a displaceable beam; a microwave receiver; an electronic data processor connected to receive a signal from the microwave receiver; wherein the microwave emitter is arranged to direct said displaceable beam towards the microwave receiver for measuring attenuation of the beam passing through each of a plurality of locations of the vegetation; wherein the electronic data processor is configured for calculating the attenuation of the displaceable beam between the emitter and receiver to obtain a 2D image corresponding to the measurement of water present in the vegetation. In particular, said beam is displaceable by the device being mounted on a vehicle which is movable along the vegetation to be measured in a horizontal direction, the microwave emitter and microwave receiver being jointly mounted in opposite ends of an arched structure.