When an aircraft is used for dusting or spraying large areas with pesticides it is known as aerial application, or more popularly as crop dusting. Commonly practiced for crops such as corn, wheat, barley and soybeans, this technique saw had exceptional success in handling desert locusts in India and East Africa.
The first known aerial application of agricultural materials, however, was to sow seeds. In 1906, John Chaytor used a hot air balloon with mobile tethers to spread seed over a swamped valley in New Zealand.
Modern crop dusting — using heavier than air machines to apply pesticides — was the product of the U.S. Agriculture department joining forces with Army Signal Corps. Under the direction of engineer Etienne Dormoy, a United States Army Air Service Curtiss JN4 Jenny was modified. On August 3, 1921, this modified aircraft was piloted by John A Macready, the only three-time recipient of the prestigious Mackay Trophy, to spread lead arsenate to eliminate catalpa sphinx caterpillars near Troy, Ohio.
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The Curtiss Jenny aircrafts, meanwhile, have an interesting history of their own. An estimated 95 per cent of American and British World War I pilots received their flight training in the Jenny. The Jennies were also assigned to fly the first official U.S. airmail and it was for this reason that the 24-cent airmail stamps featuring them were released. A hundred stamps that had the biplane printed upside-down by mistake, are now priced at over $100,000 each!
Getting back to aerial application, it came to be known as crop dusters because of the use of dry chemicals to treat crops. Liquid products, however, increasingly replaced them, be it to fertilise or treat fields for pests.
In the 1970s though, concerns were raised about the use of these aircrafts, regarding the safety of the environment and the people involved. Workers on the ground, called flaggers, were key to the operation as they used flashlights to indicate the area in the ground that the aircraft required to tend to. This exposed them to considerable danger posed by the chemicals that were being sprayed.
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Stringent regulations regarding chemicals that could be used in aerial application came about, including restrictions in the usage of human flaggers when it came to some particular pesticides. With improved chemicals, and advanced technology, including GPS to provide guidance for the person flying the aircraft, significant improvements have been made over the decades.
With increased safety, aerial application has become an indispensable part of the farming industry. They not only allow for coverage of large areas to control pests, but also eliminate the need of wheeled vehicles that might damage the crops. Aerial application has also been employed to provide irrigation in areas which have received rainfall that is lesser than usual, aiding, once again, in enhancing crop production.
ganesh.a.s@thehindu.co.in