Zone tillage tool and method

A method of tilling soil in an elongated zone in a farm field, which comprises:

• (a) providing a tool frame that carries a rotary coulter disc for rotation about a substantially horizontal axis of rotation, wherein the coulter disc has a toothed circumference defined by a plurality of circumferentially spaced teeth and notches between the teeth, wherein the teeth and the notches have edges that are sharpened to collectively form a sharpened toothed slicing edge extending substantially completely around the circumference of the coulter disc, and further including a plurality of shovel bits carried on the coulter disc with the shovel bits being circumferentially spaced around the circumference of the coulter disc;
• (b) moving the tool frame forwardly along the zone to be tilled;
• (c) rolling the coulter disc in engagement with the soil in the zone while the tool frame is moving forwardly with the sharpened toothed slicing edge on the circumference of the coulter disc cutting a slit in the soil in the zone and also cutting through any crop residue lying atop the soil in the zone as the slicing edge cuts the slit;
• (d) lifting and loosening the soil in the zone, while the tool frame is moving forwardly, with a series of rearwardly and upwardly directed soil scooping actions, wherein the soil scooping actions are produced by the shovel bits carried on the coulter disc as well as by the rolling action of the coulter disc which progressively inserts and removes the shovel bits into and out of the soil in the zone as the coulter disc rotates;
• and
• (e) performing the soil scooping actions at soil depths of more than 6 inches.