In one embodiment of a trailing arm assembly, the trailing arm assembly includes a frame bracket attachable to a planter towing frame, a first frame, and a four bar parallel linkage connecting the frame bracket and the first frame with a first pivot and a second pivot on the frame bracket and a first pivot and a second pivot on the first frame. The trailing arm assembly also includes an adjustable biasing member extending from the parallel linkage to the frame bracket. The parallel linkage is connected between the first frame and the frame bracket such that the parallel linkage maintains a parallel orientation of the first frame. The adjustable biasing member is adjustably connected to a portion of the parallel linkage.