The non-instrument rated commercial pilot departed on a maintenance test flight in a single-engine agricultural airplane. During the test flight the airplane's radial engine lost power and the pilot elected to execute a forced landing to a cotton field. The airplane sustained structural damage during the forced landing. There was no fire and the pilot was able to egress the airplane unassisted. The winds at the time of the accident were reported from 040 degrees at 11knots, gusting to 18 knots. The Federal Aviation Administration (FAA) inspector, who traveled to the accident site, confirmed the airplane sustained structural damage during the forced landing. Additionally, the inspector reported that the aircraft ran out of fuel. Despite repeated attempts by the Investigator-In-Charge (IIC), the pilot failed to return a completed Pilot Operator Aircraft Accident Report Form (NTSB Form 6120.1).