The 16,000-hour commercial pilot allowed the turbine powered agricultural airplane to get too low over the wheat field he was spraying. The landing gear of the airplane became entangled in the wheat crop and the airplane decelerated abruptly. The airplane nosed over and came to rest in the inverted position. There was no fire and the pilot was able to egress from the airplane unassisted. The pilot stated on the NTSB Form 6120.1 (Pilot/Operator Accident/Incident Report) that he allowed the aircraft to get too low and was unable to recover. An on scene investigation performed by a Federal Aviation Administration (FAA) inspector determined that there were no mechanical problems. The pilot confirmed the same finding. The airplane sustained structural damage to the fuselage and wings. Weather at the time of the mishap was reported as wind from 110 degrees at 5 knots, visibility of 10 statute miles, temperature 12 degrees Celsius, dew point 8 degrees Celsius, and an altimeter setting of 30.37 inches of Mercury.