On April 18, 1997 at 1000 central daylight time (cdt), an Air Tractor, AT-401, N1008P, was substantially damaged during takeoff from the Highmore Airport, Highmore, South Dakota. The aircraft was loaded with fertilizer and executing a takeoff from runway 12 (2,800'x150'), when it collided with a fence and flipped over. The Air Transport rated pilot received minor injures in the accident. The 14 CFR Part 137 flight was operating in visual meteorological conditions and no flight plan had been filed. A transcript of a recorded interview with the pilot conducted three days after the accident was obtained by the investigator in charge (IIC). The pilot reported that the airplane was filled with 100 gallons of fuel and approximately 2,400 pounds of fertilizer. The pilot reported that the takeoff seemed normal, and that no discrepancies with the engine or airframe were noted during the taxi, run up, or takeoff roll. The pilot reported that the airplane was lifted off approximately 1,900 feet down the runway and the airplane did not seem to want to climb after lift off. The pilot reported that he realized he was not going to clear the approaching fence, and he executed an emergency dump of the fertilizer. The pilot believed that the right wing contacted the fence first, then the airplane's landing gear contacted the road which crossed the runway's end. When the pilot was asked what he believed might have caused the accident he reported that "... it might have been a shift in the wind. Maybe the runway condition being a little soft." The pilot had flown from the airport the two day previous to the accident, and no rain was reported the day prior to the accident. A inspection of the airplane and its engine was conducted following the accident by a representative of the Federal Aviation Administration (FAA). The only discrepancy found was that two cylinders on the airplane's engine did not have compression. When these cylinders were removed from the engine, oil similar to smoke oil was found under their valves. The two cylinders which had the valves which were not seating were the cylinders which were laying inverted following the accident, and were at the lowest point of the engine. The FAA representative who examined the accident aircraft reported that similarly loaded aircraft departing under similar conditions were using approximately 80 percent of the available runway. The FAA inspector reported that the first fence the airplane hit was approximately six feet high.