A ground engaging agricultural blade, coulter, or disc having a central opening adapted to be attached to an implement for rotation about a substantially horizontal axis of rotation; the coulter or disc have an outer periphery; and plurality of step plane notches disposed in the outer periphery. The blade can be used with a hub disposed around the central opening or a spacer spool on a shaft extending through the central openings of adjacent blades, the spacer spools extending radially outwardly by a distance.