The pilot reported that when checking the fuel gauges he noted that they were indicating more fuel than should have been on board. He asked airport personnel for a ladder so he could visually check the fuel level, but then he became distracted and forgot to visually check the fuel. After approximately 1 hour 30 minutes of flight the engine lost power. The pilot selected a field in which to land; however, the airplane contacted irrigation equipment during the landing flare. Postaccident inspection of the airplane revealed that the fuel tanks were intact but empty. Both wings and the firewall were substantially damaged.