Submitted by admin on April 22, 2009 - 20:52
History of Aerial Topdressing
It seems that the idea of aerial topdressing goes back at least to 1926. In that year J. Lambert suggested that aerial topdressing of hill land might be worth trying, but his suggestion was rejected as impracticable. That this method of topdressing might be feasible was shown in 1936 by a farmer in Hawke's Bay. He used a light aircraft to oversow clover seed. In 1938 A. Pritchard, then a pilot in the Public Works Department, experimented with sowing lupin seed by air on coastal sand country. A year later fertiliser dropping was tested: the war halted further progress.
After the war the cooperation of the Royal New Zealand Air Force and the Department of Agriculture led to measurements of the distribution pattern of granulated superphosphate spread by air. The results of these tests were quite encouraging. In 1949 a private firm began experimenting with aerial topdressing. Since then expansion has been rapid. The reasons can be enumerated as follows:
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Good prices for wool and meat during and after the war have given the farmer the necessary money.
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The war left a surplus of small training aircraft which could be adapted cheaply to carry fertilisers.
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The war had created the skilled pilots needed for this work.
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The low costs and high speed of spreading fertilisers by air were quickly recognised.
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The simultaneous introduction of clovers into deteriorated pastures by surface seeding proved successful. This made possible the full utilisation of applied fertilisers.
This expansion of aerial topdressing is illustrated in the following table:
| Year | Fertilisers and Lime Applied | Area Topdressed |
| tons (000) | acres (000) | |
| 1950 | 5 | 48 |
| 1952 | 90 | 802 |
| 1954 | 205 | 1,930 |
| 1956 | 405 | 3,850 |
| 1960 | 475 | 3,960 |
| 1961 | 590 | 5,240 |
| 1962 | 620 | 5,607 |
| 1963 | 612 | 5,169 |
| 1964 | 746 | 6,588 |
For the year ending 31 March 1964, aircraft distributed 746,795 tons of fertiliser and lime on New Zealand pastures, or 22 per cent more than in 1962–63. More than half this total (404,958 tons) was dropped in the Auckland area. Altogether, the North Island accounted for 650,358 tons and the South Island for 96,437.
Aircraft now help agriculture in many ways other than in spreading fertilisers. Each year poison baits for rabbits are spread on 80,000–100,000 acres, clover seed is sown, fencing materials are delivered to inaccessible places, and spraying is carried out with insecticides, fungicides, and weedkillers.
