How a broken bolt on Yorke Peninsula changed farming around the world
In the 1860s and 1870s, South Australia and Victoria sold land cheaply to anyone willing to farm it. Much of that land was covered in mallee scrub.
Farmers cut the scrub and burnt it, but it grew straight back. Mallee regrows from a woody root under the ground, so the stumps stayed put. Ploughs of the time had rigid blades that stopped dead on a stump or snapped. Digging stumps out by hand cost more than the land was worth. The government offered £200 to anyone who could solve the problem.
An accident in the paddock
In 1876, blacksmith and farmer Richard Bowyer Smith was ploughing rough ground near Kalkabury on Yorke Peninsula when a bolt on his plough broke.
Instead of jamming, the loose blade lifted over a hidden root and dropped back into the soil. Richard and his younger brother Clarence turned that accident into a design. Each blade was hinged and worked on its own. It swung up over an obstacle, and a weight pushed it back down to keep cutting.
They named the plough Vixen. It won first prize at the Moonta show in November 1876 and was patented in February 1877.
Laughed at, then proven right
Farmers laughed at the idea of planting wheat with stumps still in the paddock. Richard also lost control of his patent and struggled for years. Parliament finally named him the inventor in 1882 and paid him £500.
Clarence opened a factory at Ardrossan in 1880. It grew to 70 workers making 14 ploughs a week. The plough opened up millions of hectares across South Australia, Victoria and New South Wales, bringing new towns, railways and ports. The factory is now a museum.
An idea that kept going
The clever part was the principle: a tool that moves out of the way of an obstacle, then goes back to work by itself. It was fitted to disc ploughs from 1906. The weight became a spring, and later hydraulics. Australian companies still sell stump jump ploughs and harrows under that name.
There was a cost. Clearing land that fast left light, sandy soils exposed to wind and water. Farmers later learned to build contour banks and plough across the slope.
The coin
The $1 Stump Jump Plough coin is part of the Royal Australian Mint's 2026 Bright Ideas collection.