The pilot had been flying for about 1 hour in the local area and was returning from the practice area at 1100 feet AGL. In preparation for landing he advanced the mixture to full rich and the engine lost power. He tried emergency procedures but the engine did not respond. The pilot stated that he moved the throttle and the mixture back and forth and switched fuel tanks, but the engine did not respond. He made a left turn and landed in a cornfield. The owner of the aircraft examined the engine but did not find evidence to explain the reported engine failure. At the time of the accident the surface temperature was 78°F and the dew point was 63°F. According to the carburetor icing probability chart, that combination of temperature and dew point is conducive to moderate carburetor icing at cruise power and serious icing at descent power. The pilot said he had not used carburetor heat during the flight.