Abstract: An impregnator system is described for electronically measuring liquid chemicals from a plurality of independent pumping systems into a fertilizer blending tank or the like. A plurality of electrically driven pumps are provided and have their intakes in communication with sources of different liquid chemicals. Each of the pumps has a discharge line extending therefrom to a main discharge line which extends to the fertilizer mixing container. An electrical flow sensor is provided in the main discharge line for sensing the rate of flow therethrough. A batch control apparatus is operatively connected to the flow sensor and the pumps for initially activating one of the pumps and for deactivating the pump when a preselected volume of liquid chemical has passed through the flow sensor.