On October 12, 1997, about 1205 central daylight time, a Cessna 172P, N945SM, registered to the Mississippi Forestry Commission, nosed over while making a forced landing in a field following loss of engine power at Wiggins, Mississippi, while on a Title 14 CFR Part 91 public use flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the commercial-rated pilot received minor injuries. The flight was originating at the time of the accident. The pilot stated that after takeoff, while climbing through 300 feet, the engine quit. He was able to restore partial power by pumping the engine throttle. He was unable to return to the airport and the aircraft nosed over while making a forced landing in a plowed field. Postcrash examination of the aircraft and engine was performed by an FAA inspector. The aircraft and engine was found to contain uncontaminated fuel and all fuel lines were unobstructed. Each engine control was still connected and operated properly. After the aircraft was recovered from the field, the engine was started and operated to 2,000 rpm with no evidence of failure or malfunction. The engine was not operated to full power due to a bent propeller. After the engine run, the carburetor was removed and disassembled. No evidence to indicated mechanical failure or malfunction was found in the carburetor. (See FAA Inspector Statement). Carburetor icing probability curves showed the aircraft was not operating in conditions conducive to carburetor icing at rated power.