A reverse-rotational-rotary tiller with special shaped blades was used for experiments to investigate the dynamic interaction between soil and machinery. This tiller provided tilled clods without re-tilling especially from clayey fields, and the clods provided good samples for evaluating the dynamic interaction between the soil and the blades during the cutting process of approximately 10 ms. The clods obtained in the heavy clay field tests show zigzag contours, large periodic cracks, undulating free surfaces and smoothly cut surfaces. New details of rotary soil cutting considering clod formation are presented. The clod shape is confirmed to be of a fractal pattern in terms of the contour, crack and crack area distribution.
