The aircraft was engaged in spreading superphosphate from a strip on the property being treated. The pilot said that during the takeoff the aircraft became airborne prematurely due to surface undulations. In order to keep the aircraft flying he attempted to lower a little more flap, but inadvertently selected "flaps up", resulting in the aircraft settling onto the strip. Although the pilot realised his error and reselected takeoff flap, he was too late to prevent the tail of the aircraft from striking the boundary fence. He could see the left tailplane was damaged and determined the left elevator was missing by observing the ground shadow of the aircraft. The aircraft was able to be flown for a safe landing.