Farrer released numerous new wheat varieties but the best known was Federation, a cross between Purple Straw and Yandilla, which was a Canadian Fife and Indian wheat cross. Named in 1901, by the 1919-20 season Federation comprised some 80 per cent of all the wheat harvested in Australia. Farrer died in 1906 but by then the benefits of wheat breeding had been well established, and the development of wheat breeding programs became a major activity of most departments of agriculture.

The new varieties of wheat gave increased yields, and the yields were further enhanced by the growing use of superphosphate. However, the lack of soil moisture and low soil fertility, particularly a lack of nitrogen, were still a problem. With the movement of wheat growing into the drier regions American experience became more relevant than British and, by the turn of the century, the Americans were looking to science to help dry land farming. At this time the capillarity theory of water movement in soils was in vogue and it was claimed that a dust mulch on ploughed land would prevent water loss from the soil. The theory was wrong but it led to positive improvements in practice. The South Australian Government took a particular interest in possible new systems of dry farming and encouraged research on the topic.

A system of fallowing was developed and it was thought that a fallow of 8-11 months before seeding was most effective. Its benefits were eventually shown to be in removing weeds, and thus preventing water loss through the weeds, and increasing supplies of available nitrogen through promoting the release of soluble nitrogen from organic matter. On the debit side, however, fallowing had a bad effect on soil structure. Nevertheless, with the introduction of fallowing, a further step was taken towards the development of a characteristic system of Australian wheat production.

This development was more or less completed after the 1930s depression. Prior to this, in the 1920s, there had been a rapid expansion of wheat growing into marginal areas. Drought and excessive cropping led to severe soil erosion and Australia suffered its local equivalent of the American dust bowl. Rehabilitation of wheat production required the recognition that some areas were too marginal for cropping and also that superphosphate applications alone were not enough to maintain soil fertility under constant cropping, even with fallowing. Finally, after about 150 years of settlement, a stable, viable system of wheat cropping was evolved. Sheep and other livestock were introduced and wheat was grown in a system which included both a fallow and a rotation, from one to four years or more, under a legume-grass pasture. As a result the wheat growing region became known as the wheat-sheep zone.

Australian Academy of Technological Sciences and Engineering