in a converted long range fuel tank in Avenger NZ2504 and dropped it over the concrete runway at Ohakea. (NZ2504 is now preserved in the Royal New Zealand Air Force Museum). The superphosphate was too powdery but a more granular form was found before final trials measuring distribution pattern of spread by air on 16 September 1948. The results were considered very promising. Trials proceeded to hill country at Te Mata near Raglan, and were extended to three other sites. For 1949 a Research and Development flight was formed under Stan Quill, equipped with the three Avengers and a Douglas DC-3, while instructions were sent to England to modify 2 RNZAF Miles Aerovans then on the production line to carry one-ton hoppers. A ground convoy of station wagon, car, one-ton truck, jeep, fuel tanker and radio van supported them. The 1948 fuel tank was replaced by a hopper with sides angled at 60° with a vibrating rod to loosen the superphosphate. Large-scale topdressing started on 14 March 1949 spreading clover-super mix. The "Topdress III" trials culminated on 21 May 1949 with a demonstration drop on 11 different properties close to Masterton in front of large numbers of farmers and press. These trials were calculated to have spread 2.5 cwt/acre (31,000 kg/km2) at an all-up cost of 15 shillings ($1.50) per acre (4047 m2), despite the use of inappropriately over-powered combat aircraft. Further public displays were given to cabinet ministers on 30 August at Johnsonville, on 9 September at Ohakea and at a 17 September Air Force Day air show. As these trials were a resounding success, in addition to the Aerovans, 12 Bristol Freighters then under construction for the RNZAF were modified to take superphosphate hoppers. Following these successful trials, in 1950, farmers' groups lobbied the government to have the RNZAF provide subsidised topdressing with the Bristol freighters and even advocated using large Handley Page Hastings. But by this time government work was being overtaken by private enterprise as ex-airforce pilots bought New Zealand-built De Havilland Tiger Moth biplanes cheaply, placed a hopper in the front seat and went into business flying from the paddocks of any farmer willing to pay. The government became reluctant to spend money on interfering with the increasing number of commercial operators. Research in other nations Australia The first experimental topdressing in Australia was done by a private Tiger Moth in 1948. Great Britain Faced