The aircraft collided with the ground during a turn-around. The hopper dump valve on the aircraft was found closed after the accident. The fuel tanks were reportedly full (54 gallon capacity) and 120 gallons of Benlate, a non-toxic liquid herbicide, had been loaded aboard N9270R prior to departure. The aircraft was seen in the vicinity of the accident area after it arrived on the scene but no one actually reported seeing the crash or the final swath run. The flight was operated without the assistance of ground personnel. The wreckage path and the position of the wreckage relative to the field were consistent with the pattern expected from a crash following a turn-around maneuver after the pilot made a west-to-east run. No mechanical or physical discrepancies were found that were considered contributory to the accident. All damages noted to the airframe were determined to be impact related. The cage around the pilot's cockpit was intact revealing no impact damage. Pilot's seatbelt and shoulder harness hardware was intact. However, the fabric belts were consumed by fire.