An apparatus is provided for introducing a discrete, predetermined amount of material into soil at a plurality of predetermined points in the soil which includes a container for holding the material to be introduced into the soil, and tubing in fluid communication with the container at a first end thereof. At least one electrically controlled injector is provided in fluid communication with a second end of said tubing. Also, at least one shank is provided, which includes a base, and an injector mounting member attached to a surface of the base that is adapted for detachably mounting the electrically controlled injector onto the base. In addition, a controller is provided for activating the electrically controlled injector to introduce the material into the soil. Accordingly, enhanced control of the injection of the material into soil is achieved, and maintenance can be performed easily.