The apparatus is intended for the breaking of ground used for the cultivation of plants with a probe, whereby by means of a rapid closing valve compressed air and by means of an injector valve a substance may be introduced into the soil in an impact like manner. The rapid closing valve is arranged in the upper area and the injector valve in the lower area of an intermediate reservoir for the substance. The rapid closing valve is followed by an injector tube with a compressed air outlet. The injector tube may be raised in case of an open rapid closing valve with a delay in time from an injector valve seat of the intermediate reservoir to release the injector valve.