THE PILOT OF THE CESSNA AG TRUCK STATED THAT HE DEPARTED WITH 50 GALLONS OF FUEL AND FLEW FOR ONE AND A HALF HOURS, CONDUCTING AGRICULTURAL OPERATIONS. HE STATED THAT HE HAD A POWER LOSS DURING A PULL UP AND MADE A FORCED LANDING ATTEMPT. A TOTAL OF APPROXIMATELY FOUR GALLONS OF FUEL WERE DRAINED FROM THE AIRCRAFT WHEN IT WAS RECOVERED, AND THE ENGINE WAS RUN WITH NO APPARENT MECHANICAL DISCREPANCIES NOTED.