THE PILOT LANDED THE LAND/SEAPLANE IN THE GRAIN FIELD AFTER EXPERIENCING A TOTAL LOSS OF POWER. THE LANDING WAS UNEVENTFUL. PERSONNEL FROM THE AIRPORT FIXED BASE OPERATOR BROUGHT THE PILOT 10 GALLONS OF GAS WHICH HE PUT INTO THE FUEL TANKS. THE PILOT DEPARTED THE FIELD, BUT THE AIRPLANE'S LEFT AMPHIBIAN SKID STRUCK THE HIGH VEGETATION COVERED BARBED WIRE FENCE.