The purpose of the flight was to spray a soybean field about 1/2 mile north of the airstrip. There are no known witnesses to the crash, but a person in the area heard the engine 'pop', then engine sound ceased; seconds later the sound of impact was heard. The aircraft struck the ground in a nose down, slight left-wing-low attitude, coming to rest in the impact crater, suggesting a slow forward speed and high vertical rate of descent. There were no other ground contact points. The hopper burst on impact and the Lanate sprayed out ahead of the aircraft in a fan shaped pattern. The pilot's seat belt and shoulder harness webbing failed in overload and the pilot was ejected from the aircraft. The restraints were weathered and blanched in appearance. The propeller showed no evidence of rotation, however, an exam of the engine revealed no evidence of pre-impact malfunction or failure. The fuel tanks had ruptured but there was a lack of fuel odor. The fuel lines, fuel selector and fuel pump contained only residual fuel. The carburetor was broken.