For more general information about agricultural aircraft

Agricultural aircraft

An agricultural aircraft is an aircraft that has been built or converted for agricultural use - usually aerial application of pesticides or fertilizer ; in these roles they are referred to as "crop dusters" or "top dressers"...

, see aerial application

Aerial application

Aerial application, commonly called crop dusting, involves spraying crops with fertilizers, pesticides, and fungicides from an agricultural aircraft. The specific spreading of fertilizer is also known as aerial topdressing....

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Aerial topdressing is the spreading of fertilisers such as superphosphate over farmland with the use of aircraft. Aerial topdressing was developed in New Zealand in the 1940s and was rapidly adopted elsewhere in the 1950s.
The first known aerial application

Aerial application

Aerial application, commonly called crop dusting, involves spraying crops with fertilizers, pesticides, and fungicides from an agricultural aircraft. The specific spreading of fertilizer is also known as aerial topdressing....

 of agricultural materials was by John Chaytor, who in 1906 spread seed over a swamped valley floor in Wairoa

Wairoa

Wairoa is a town in New Zealand's North Island. It is the northernmost town in the Hawke's Bay region, and is located on the northern shore of Hawke Bay at the mouth of the Wairoa River and to the west of Mahia Peninsula...

, New Zealand, using a hot air balloon

Hot air balloon

The hot air balloon is the oldest successful human-carrying flight technology. It is in a class of aircraft known as balloon aircraft. On November 21, 1783, in Paris, France, the first untethered manned flight was made by Jean-François Pilâtre de Rozier and François Laurent d'Arlandes in a hot air...

 with mobile tethers.

The first known use of a heavier-than-air machine in aerial topdressing occurred on 3 August 1921 when as the result of advocacy by Dr Coad, a USAAC Curtiss JN4 Jenny piloted by John A.