The pilot of the aerial application flight attempted a takeoff on runway 27 (2640 feet by 100 feet, turf) during which the airplane hit a bump 2/3 down the runway, became airborne, and then descended into a corn field. The airplane impacted the cornfield upright and sideways resulting in a deformed fuselage and substantial damage. The pilot stated in his recommendation not to takeoff at a heavy weight on a wet runway. The density altitude at the time of the accdient was approximately 2,854 feet mean sea level.