On August 3, 2012, about 0919 central daylight time, a Weatherly 620B, N2008S, sustained substantial damage when it impacted the ground following a loss of engine power during takeoff from a field near Holcomb, Kansas. The pilot received minor injuries. The aircraft was owned and operated by Farmers Aviation, Inc., under the provisions of 14 Code of Federal Regulations Part 137 as an agricultural application flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight was originating at the time of the accident.The pilot reported that he completed a preflight examination and pre-takeoff run-up of the airplane with no anomalies noted. He stated that the takeoff roll was normal and the airplane lifted off in a reasonable distance. He did notice about a 30 rpm drop during takeoff compared to other takeoffs but the engine speed was still within the normal operating range. After gaining about 50 feet of altitude the airplane started losing power. The pilot attempted to drop the chemical load in an effort to stay airborne but the airplane impacted an open field about one mile north of the airstrip. The pilot stated that he thought the engine had lost almost all power by the time the airplane impacted the field. The pilot did not mention using carburetor heat during the pre-takeoff run-up or during the power loss event. Examination of the airplane and engine revealed no preimpact anomalies that would explain the loss of engine power. Subsequent re-examination of the engine also revealed no anomalies. The carburetor and magnetos were sent to the NTSB investigator-in-charge for further examination. The carburetor was disassembled and no anomalies were noted. The right magneto was broken due to the impact; however, no anomalies were detected upon examination. The left magneto was intact and produced spark when rotated. At 0854, the weather conditions recorded at the Garden City Regional Airport, Garden City, Kansas, about 15 miles east of the accident site included a temperature of 22 degrees Celsius and a dew point of 19 degrees Celsius. According to the carburetor icing chart found in Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35, entitled "Carburetor Icing Prevention", the reported temperature and dew point fall in the range of susceptibility for icing during glide and cruise power settings, and within the range of susceptibility for serious icing during glide power.