No.8 Re-wired: Top-dressing

For most of our history, New Zealand has basically been a big farm, pumping out products for the United Kingdom. It’s a gross over-simplification, but essentially the colony of New Zealand, from its establishment in the early 1800s through to when the UK joined the European Union in the 1970s, was the place that grew the Mother Country’s meat, wool and milk – all from the 40-odd million acres of farmland we are blessed with.

As any farmer will tell you, the constant sowing, growing and reaping of crops will deplete the natural minerals in the soil over time. Leaving aside the wider ecological implications of felling forests to create pastureland, the fact that pastureland becomes less productive is a real challenge to efficiency.

Add to that the fact that sowing seeds, particularly into the hills and vales of steep New Zealand, is difficult, expensive and inefficient: now you’ve got a problem that needs ingenuity and inventiveness. 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 of this feat is often incorrectly quoted as Wairoa: it was in fact 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 (a famous soldier during World War I, later knighted) spread grass seed over the family farm from a hot-air balloon. Most historians credit Alan Pritchard with pioneering what we now call ‘aerial top-dressing’ – 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 the government’s Public Works Department in the 1930s and 1940s. 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, then 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 logbooks of his flights to allow him more time to trial his ideas.

Throughout the period 1939 to 1943 he experi- mented until he had some quite specific and exact results to show that this method of dispersing seeds and fertiliser 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 logbooks, the minister gruffly congratulated him, and told him that if anyone had an issue with it, to send them to him.

With that endorsement, top-dressing was ready for mainstream use. It was the perfect time to start the endeavour – after World War II ended there were a lot of qualified pilots looking for jobs, and a number of surplus planes left over from the war effort. Indeed, at one point it was even suggested that the RNZAF should take on top-dressing as a core function, but despite undertaking some successful trials using DC3s and other air force planes at Ohakea, the private sector took on the task and a successful new approach to farming took off. Known more commonly as ‘crop dusting’ in other parts of the world, top-dressing is still a core part of how we maintain the land. The lush pasturelands of New Zealand – and a number of happily employed private pilots – owe their success to Pritchard and his predecessor Chaytor.