A dosing unit, for the controlled delivery of a solid material, including a silo, for containing the material to be delivered, having on the bottom a discharge mouth, said discharge mouth being circular, at least one extraction auger arranged inside said silo and operable in rotation around a vertical axis, at least one scraper member, located inside said silo and associated with said discharge mouth operable in rotation around said vertical axis, first actuation means of the extraction auger and second actuation means of the scraper member, at least one shutter component positioned below the discharge mouth, and moving means operatively connected to the shutter component to move it with respect to the discharge mouth.