Whilst cruising at 3,500ft over Bendigo city enroute to Melbourne, the engine commenced vibrating and rattling. The pilot, on his first solo navigation exercise, shut down the engine and made a forced landing onto Bendigo aerodrome. The aircraft touched down on an unprepared area causing the nose landing gear to collapse. The aircraft was recovered and the engine sent to a maintenance organisation for teardown inspection. Other than one unservicable sparking plug , the engine was considered to be within all in-service tolerances, and was undamaged. It is possible that the low time student pilot reacted to the vibration occasioned by the failed sparking plug and shut the engine down when in reality some significant power was available. The subsequent approach had the aircraft landing in an unmade area that overstressed and failed the nose landing gear support structure.