Abstract: The mixing head comprises a pair of opposed, spaced apart, generally vertical discs that are generally aligned with the direction of travel, although they are slightly angled so as to be wider apart at their front ends than at their rear ends. The discs are rotatably mounted to a free floating frame. Each disc has a plurality of radially extending, elongated, broad, rigid, chisel-like teeth which extend from the disc central portion out beyond its circumferential rim. The discs are driven to rotate against the direction of travel. When rotating, the disc and teeth formations operate to cut down into the coil and excavate it in portions carried by the teeth. The portions are moved inwardly by the angled formations and then thrown and dropped to the rear. The furrow formed has a flat-topped ridge overtopped with a loose mix of excavated soil and humus. The furrow is a good growing site for implanted seedlings.