Witnesses reported that the agricultural airplane attempted to depart the private airstrip with a load of potash, but that the airplane "never made it off the ground" and impacted crops and terrain located at the end of the runway. The airplane nosed over and came to rest inverted. The rudder was crushed and the engine separated from the airframe. The pilot did "not remember any of the accident." The accident flight was one of several flights completed that day and the day before. The estimated weight of the airplane at the time of takeoff was 11,200 lbs, and the airplane's maximum gross weight was 12,500 lbs. The runway is approximately 1/2 mile in length with 1,600 feet of asphalt and the remaining runway is grass/turf. Postaccident examination revealed no anomalies with the airplane.