Portal:New Zealand/Selected article/Week 10, 2006
Aerial topdressing is the spreading of fertilisers such as superphosphate over farm land. Aerial Topdressing was developed in New Zealand in the 1940s and was rapidly adopted elsewhere in the 1950s. Aerial topdressing is distinct from crop dusting, which is the spraying of insecticides and fungicides from the air.
Much of New Zealand's central North Island farm land, given to returned servicemen after World War I, had proven deficient in trace minerals such as cobalt, copper and selenium, forcing difficult topdressing by hand in rough country, or abandoning the land for forestry and the possibility of using aircraft soon occurred. Spreading Superphosphate by agricultural aircraft was independently suggested by two New Zealanders in 1926, but the first trials didn't occur until the late 1930s. By the end of the 1940s, aerial topdressing was an industry.