The 5,002-hour pilot reported that as he advanced the throttle to increase engine power while on final approach for landing, "none was available." The airplane settled within tall grass just short of the runway. Subsequently, the airplane rolled into a 10-15 foot deep gulley and came to rest upright. No anomalies were noted during the examination of the airframe. The engine was successfully run and was found to be free of anomalies. The reason for the loss of engine power was undetermined.