The question of what constitutes secondary tillage is particularly important if we are to be a discriminating consumer of the vast array of tools available today. For the sake of clarity, I would suggest that secondary and primary tillage are distinctly different but not necessarily because of surface appearance changes.

The goal of primary tillage should fundamentally effect water and air exchange potential of the plow layer. (For an in-depth look at the anatomy of Primary Tillage- here .)

So secondary tillage tools are highly focused on preparing the surface for planting operations. This may include residue resizing and modest amounts of residue incorporation. Virtually none of these tool designs are capable on a regular basis of penetrating deeply enough to achieve the goals of primary tillage.

link to Besler Choppers

link to Phillips harrow

link to Landoll "To The Max"