It is made of a hot galvanized tank which permits the penetration of controlled quantities of fertilizers into the water. The percontage of the penetration of fertilizers is determined by the difference of pressure between the inlet flow of the water and its evacuation from the tank. The pressure difference is controlled by the intermediate valve in the rain-wing or similar. The quantity of the fertilizer outlet (time of evacuation from the tank) depends both on the pressure lowering and the diameter of inlet and outlet pipes of the tank. When the fertilizer is solid, its outlet time will be longer than liquid fertilizers; moreover it varies according to the type of fertilizer. It is used in drip installations a lot.