On July 26, 2001, about 0830 central daylight time, an Ag-Cat Corporation G-164B, N80083, piloted by a commercial pilot, sustained substantial damage when it impacted the ground and nosed over during a forced landing following a loss of engine power near Wallace, Nebraska. The 14 CFR Part 137 aerial application flight was not on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The pilot reported no injuries. The local flight originated from a private airstrip near Wallace, Nebraska at 0820. A postaccident examination of the airplane was conducted. The wings had been removed for transport from the accident site. The transport crew reported to the Federal Aviation Administration inspector that there was a small quantity of fuel in the wing fuel tanks at the time of the wing removal. The aircraft engine was visually examined and no anomalies were found. Subsequent to the visual examination of the engine, a temporary fuel system was fabricated to facilitate an engine operational check. The engine operated at low and mid-range power settings with no operational problems found. The pilot reported to a Federal Aviation Administration Inspector that he was unsure of the fuel quantity at the time of the accident. In his written report, the pilot reported having 71.7 gallons of fuel on board at the last takeoff. The pilot said that he had just initiated a pull-up to about 100 feet to return to the airport when there was a total power failure. He said that he checked the magnetos with no change and then executed a forced landing in a, "...soft summer fallow field."