Abstract: An implement for aerating and dethatching golf courses, athletic fields and other sodded fields has multiple aerator units each including a plurality of earth piercing aerator elements mounted on a shaft. Arms of each aerator unit supporting the shafts are independently swingable to move the shafts between horizontal positions and positions inclined from horizontal in accordance with the contour of the ground or encountered soil conditions as the aerator is advanced across the earth. A spring assembly urging each aerator unit toward the ground has structure for causing any upward swinging movement of the arms of each unit to be resisted by the weight of the frame whenever such arms are pivoted upwardly past a predetermined elevation, in order to provide additional force where highly compacted soil conditions are found.