Abstract: A device in the nature of a rotary tiller equipped for traveling through fields as well as uneven terrain, for effectively chopping up encountered clods, vegetation and debris, and mixing same with the soil. We utilize a framework in which either of two different types of bladed, couner-rotating rotors may be effectively mounted, with one type of rotor having a number of outwardly extending teeth that are adapted for penetrating the ground as the tiller device moves thereover. The outermost portion of each tooth is provided with a novel cutting blade, which may interact with a stationary shear bar, with this type of blade being well adapted for chopping up encountered vegetation and for mixing it thoroughly with the soil.