On July 16, 2013, about 1700 central daylight time, the pilot of a Piper PA-22-125, N663A, made a forced landing in a cornfield after the engine lost power near Mapleton, Minnesota. The pilot and a passenger were not injured. The airplane was substantially damaged. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed. The flight originated at an undetermined time from Wells (68Y), Minnesota, and was en route to Mankato (KMKT), Minnesota.The following is based on the pilot's accident report, an interview he had with Federal Aviation Administration (FAA) inspectors, the passenger's statement, and witness statements: The pilot said he telephone the Flight Service Station and obtained a weather briefing, then he performed a thorough preflight inspection of the airplane that included draining all three fuel sumps. He said there was no water or sediment in the tanks. No fuel was added. He made one solo flight to regain currency, then flew his father around the city of Wells. The pilot then took his brother and departed for Mankato. North of Mapleton at 2,500 feet, the engine "sputtered." The pilot applied carburetor heat and adjusted the fuel mixture to full rich. The engine continued to sputter. The pilot then switched to the right tank. The engine then "quit." The pilot made a forced landing in a corn field and nosed over. FAA inspectors took fuel samples from both the left and right wing fuel tanks, and from the gascolator fuel line. A substantial amount of water was recovered. According to the inspector, the airplane had been parked outside and there had been recent heavy rainfalls in the area.