Although Australia is mostly arid, the nation is a major agricultural producer and exporter, with over 325,300 employed in agriculture, forestry and fishing as of February 2015. Agriculture and its closely related sectors earn $155 billion-a-year for a 12% share of GDP. Farmers and grazers own 135,997 farms, covering 61% of Australia's landmass. Across the country there is a mix of irrigation and dry-land farming. The success of Australia to become a major agricultural power despite the odds is facilitated by its policies of long-term visions and promotion of agricultural reforms that greatly increased the country's agricultural industry. The CSIRO, the federal government agency for scientific research in Australia, has forecast that climate change will cause decreased precipitation over much of Australia and that this will exacerbate existing challenges to water availability and quality for agriculture. There are three main zones: the high rainfall zone of Tasmania and a narrow coastal zone (used principally for dairying and beef production); wheat, sheep zone (cropping (principally winter crops), and the grazing of sheep (for wool, lamb and mutton) plus beef cattle) and the pastoral zone (characterised by low rainfall, less fertile soils, and large scale pastoral activities involving the grazing of beef cattle and sheep for wool and mutton). An indicator of the viability of agriculture in the state of South Australia is whether the land is within Goyder's Line. History Agriculture in Australia has a lively history. Aboriginal Australians have been various described as hunter-gatherer-cultivators and proto-farmers, as there is evidence that farming activities were undertaken prior to the arrival of Europeans, including tilling, planting and irrigating. However, these practices were non-industrialised and complementary to hunting, gathering and fishing. Whether the people could be termed agriculturalists is controversial. In 1788, the first European settlers brought agricultural technology from their homelands which radically changed the dominant practices. After some initial failures, wool dominated in the 19th century and, in the first half of the 20th century, dairying increased in its popularity driven by technological changes like canning and refrigeration. Meat exports were very significant in the development of Australian agriculture. By 1925 there were 54 export freezing works, capable of killing 6000 cattle and 90,000 sheep and lambs daily. Initially meat for British markets had to be frozen, but later beef could be exported chilled. Production Australia's main agricultural products are very contrasting crops: sugar cane (typical of tropical countries), wheat and