Harrow downforce adjustment

A tillage implement, comprising:

• an implement frame;
• and
• a harrow attachment supported by the implement frame, including:
• a harrow drawbar configured to mount to a frame member of the tillage implement;
• at least one harrow rank having a rank bar supporting a plurality of harrowing tools;
• a pivot link pivotally coupling the at least one harrow rank to the drawbar to allow the at least one harrow rank to trip by pivoting upward toward the drawbar from a home position in which the at least one harrow rank is farthest away from the drawbar;
• a downforce spring coupled to the drawbar and configured to be in a fixed length state when the at least one harrow rank is in the home position and in a variable length state when the at least one harrow rank is tripped, when in the variable length state the downforce spring applies a biasing force to the at least one harrow rank away from the drawbar, and when in the fixed length state the biasing force is removed;
• and
• an adjustment mechanism coupling the downforce spring to one of the at least one harrow rank and the pivot link in one of a plurality of adjustment locations, having openings with centers arranged along a radius extending from a mounting location of the downforce spring, in each of which the at least one harrow rank is in the home position and the downforce spring is in the fixed length state.