On March 11, 2004, about 1000 Pacific standard time, an Ayers Thrush S2R-600, N8520V, experienced a total loss of engine power and made an off airport landing in a plowed field near Calipatria, California. Farm Aviation, Inc., was operating the airplane under the provisions of 14 CFR Part 137. The commercial pilot, the sole occupant, was not injured; the airplane sustained substantial damage. The local flight departed Cliff Hatfield Memorial Airport, Calipatria, about 1000. Day visual meteorological conditions prevailed, and a flight plan had not been filed. In a written statement, the pilot reported that prior to takeoff, he loaded the airplane with chemical application and had the left tank filled with fuel. During his takeoff roll, all engine instruments showed normal indications. After the airplane was airborne, he felt the engine lose power. The instrument gauges continued to show normal indications. He decided to open the dump gate in an effort to release the chemical load, and prevent the airplane from stalling. The airplane lost complete power, and the pilot began to search for adequate terrain to land. During touchdown in a field, the airplane bounced back into the air and veered to the left, crossing several field rows. Upon returning back down onto the terrain, the airplane ground looped. After the accident the pilot found out that prior to departure, the airplane was refueled with Jet-A fuel, as opposed to the required Avgas. The pilot reported no preimpact mechanical malfunctions or failures with the airplane. During a telephone interview with the National Transportation Safety Board investigator-in-charge (IIC), the operator stated that, while at the fuel island, a new employee had mistakenly filled the fuel truck with Jet-A fuel. The employee then used the Jet-A fuel in the truck to refuel the airplane. In an effort to help avoid similar problems, the operated has ordered new nozzles for the fueling points to help distinguish the Jet-A tank from the Avgas tank.