In 1906, one John Clervaux Chaytor (b. 1836, d. 1920) became the first person in the world to apply agricultural materials aerially - he went up in his hot air balloon and threw seed into the air so that it would spread over the valley below. The location is often incorrectly quoted as Wairoa, but in fact this happened in Wairau, in Marlborough, on the family farm 'Marshlands'. This mechanism of spreading seed was one the family kept at, and as a young man John's son Edward Chaytor (later knighted, and a famous solider during WWI) spread grass seed over the family farm from a hot-air balloon.
Most historians credit Alan Pritchard with pioneering what we now call 'topdressing' - flying a plane over a patch of ground and releasing fertiliser or seeds (actually often both at the same time) over the land. Pritchard was a pilot with government's Public Works department in the 1930s and 1940s, when he thought of the idea of sowing seeds from his plane after eating grapes while flying, and throwing the seeds out of the window. A few days later he experimented with sowing lupin seeds by sewing a sack of seeds to a downpipe, and flying at different heights to work out the right dispersal rate.
Strictly speaking, his employers didn't really know about his aerial experiments, and he forged the log books of his flights to allow him more time to trial his ideas. Throughout the period 1939 to 1943 he experimented until he had some quite specific and exact results to show that this method of dispersing seeds and fertilizer was extremely economical. After he published his results, a government minister he regularly piloted asked him how he'd worked it all out. When Pritchard admitted what he'd been doing with the log books, the minister gruffly congratulated him, and told him that if anyone had an issue with it, to send them to him.
With that endorsement, topdressing was ready for mainstream use.