No-tillage and conservation farming practices in grain growing areas of Queensland - a review of 40 years of development

Early agricultural practices in Queensland inadvertently led to accelerated soil erosion. During the 1940s, the Queensland Government initiated a soil conservation service that worked with the principles of matching land use with its capability, as well as runoff management using earth structures such as contour banks and grassed waterways. A concerted effort began in the 1960s to develop and adapt farming systems that maximised retention of crop residues to maintain surface cover to complement the earthworks. Investigation and promotion of farm machinery capable of dealing with high stubble levels commenced in the mid-1970s. Demonstrations of the benefits of reduced and no-tillage conservation farming practices for improved productivity and soil conservation also began at this time. The combined research, development and extension efforts of farmers, grower organisations, agribusiness and government agencies have contributed to an increase in the understanding of soil–water–crop interactions that have led to the adoption of no-tillage and conservation farming practices in Queensland. In 2005, the overall area under no-tillage was ~50% of the cropping land in the main grain growing areas of southern and central Queensland, but was potentially as high as 85% among some groups of farmers. Conservation farming practices, in their many forms, are now regarded as standard practice, and the agricultural advisory industry is involved considerably in providing advice on optimum herbicide application and crop rotation strategies for these practices. Factors hindering greater adoption of no-tillage include: farmer attitudes and aspirations, machinery conversion or replacement costs, buildup of soil and stubble-borne plant diseases, use of residual herbicides that may limit crop options, dual use of land for grazing and cropping, herbicide resistance, buildup of hard-to-kill weeds, the need for soil disturbance in some situations, and concerns by farmers about the effects of herbicides on the environment and human health. Developments that may aid further adoption of no-tillage systems include: ongoing machinery modifications that allow greater flexibility in the cropping systems, refinement of controlled traffic farming and precision agriculture, improved crop resistance or tolerance to plant diseases associated with stubble retention, availability of more crop options and rotations, development of a broader spectrum of effective herbicides and the use of genetic modification technologies to breed herbicide-resistant crops.