Temporal and spatial variability of the cropping limit in South Australia

Since its establishment in 1865, Goyder’s Line in South Australia has represented the division between land suitable for cropping and land seen as viable for grazing. Despite this, current cropping areas extend beyond Goyder’s Line. In this study, the 220 mm growing season (April to October) rainfall isohyet is used as a proxy for Goyder’s Line to assess its temporal and spatial variability. Using indices of the El Niño Southern Oscillation, Indian Ocean sea surface temperature variability, Southern Annular Mode and subtropical ridge, it is shown that climate state significantly influences the location of the 220 mm growing season rainfall isohyet. This implies that the boundary between viable and non-viable cropping areas (i.e. Goyder’s Line or ‘nature’s limit’) is non- stationary. These results also indicate the key influences on South Australia’s climate and have important implications globally for agricultural practices operating in or bordering semi-arid environments.