On August 14, 2008, at 1045 central daylight time, a Bell helicopter 47G-3B, N47AH, collided with the terrain following a loss of control while taking off from a support truck in Kenyon, Minnesota. The pilot was not injured and the helicopter was substantially damaged. The aerial application flight was being operated under Title 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed and no flight plan was filed. The local flight was originating at the time of the accident. The pilot reported he had flown several aerial application flights earler in the day and that the humidity had increased as the weather cleared. He stated that the initial takeoff was normal. The pilot stated that when he was about 100 yards from the support truck, the rotor rpm began to decay and the helicopter settled into a soybean field. The spray boom caught in the crop and the helicopter pitched forward which resulted in the main rotor blades contacting the ground. The aft section of the tailboom, including the tail rotor, separated from the helicopter. The pilot reported there was no mechanical malfunction/failure with the helicopter. He did report that he should have decreased his load due to the weather conditions.