An agricultural tool assembly (21) disclosed is used with a planter attachment. Assembly (21) includes a rotary disk (23) mounted on a lower end of a rotary spindle (25). An offset mount for the spindle includes a shank (41) adapted to be received in the vertical slot of a clamp (22) and a sleeve (45) offset from the shank for rotatably supporting the spindle. The sleeve is connected to the shank, using a bifurcated portion comprised of spaced plates (47, 48) connected to the sleeve with a lower pivot member (52) and an upper fastener (58) extending through arcuate slots (61 and 62) in the space plates. The planter attachment has a support frame that disposes the tool assembly (21) ahead of the planter (230) to cut the old crop prior to having the planter deposit the seed.