The Goyder Line is a line of reliable rainfall in South Australia. It separates land suitable for crops from general grazing land. It originated when the then Surveyor-General of South Australia, George Goyder, evaluated pastoral properties in the north of the State after a period of severe drought.

George Goyder was a surveyor who migrated to Sydney in 1848 and three years later settled in Adelaide. There he entered the civil service and served with the Department of Lands from 1853 until his retirement in 1894. He became South Australia’s Surveyor-General in 1861. Goyder surveyed much of the area between Lake Eyre and Lake Torrens in northern South Australia. He was not always popular with land-holders as his assessments of their property were used to classify grazing leases, rents and rights of renewal.

During the severe drought of 1863-66, Goyder was called upon to reassess the value of many properties that had suffered from the prolonged dry spell. His instructions were to lay down on the map ‘the line of demarcation between that portion of the country where the rainfall has extended, and that where the drought prevails’.  After travelling more than 5,000 km on horseback, he drew what came to be referred to as the Goyder Line. This defined the limits of the land considered safe for agriculture.

The annual rainfall considered to be suitable for crops was 12 inches (30 centimetres) a year. The zone suitable for cropping, between the 20 and 12-inch rainfall lines, became known as the wheat belt.

During the 1870s, good seasons, combined with a scarcity of agricultural land, persuaded the South Australian Government to ignore the Goyder Line and sell land to the north. This experiment did not end well, with poor seasons occurring during the 1880s. Farmers gradually moved back south of the Line.

The Goyder Line is still regarded as important in the discussion of agriculture in marginal country. In 2007 Dr Peter Hayman of the South Australian Research and Development Institute said: “The story of Goyders’ Line is a cautionary tale against over-confidence arising from a few years of above-average rainfall. There has always been a wider fascination with the margin between arable land and the desert and it epitomises risk at a time when we are seeing continuing drought and worrying indicators of climate change.”