Abstract: A sub-soil injection device injects a soil additive, such as a pesticide, as included in a foam below the surface of soil. It concurrently distributes the foam into soil as the foam is injected resulting in an improved uniformity of distribution of soil additive in soil. The device comprises a tubular structure which mounts into the soil from a vehicle. It has first and second portions, leading and trailing portions, a lumen along its length, lateral portions and a plurality of spaced apart ports. Each port communicates the lumen with the trailing portion. Foam flowing out the ports moves backwardly. A shank structure precedes and shields the leading portion of the member. The shank structure has a forward-facing portion adapted to cut through soil. The shank structure and member are motivated by the vehicle in a forward direction through the soil. An apparatus utilizing the shank structure, the vehicle and a foam generator and a method of depositing a soil additive plowing in of foam are also set forth.