feeding a hot, hungry world - agriculture in the face of climate change
Box 3 | Australian agriculture over time
wheat suited to the Australian climate.
Source: stock.xchng www.sxc.hu
Since the beginning of the 20th century, agricultural production in Australia has steadily increased, with distinct jumps in production related to specific advances in the understanding of plant physiology and improved land management developments. Australian farming has seen a shift from the traditional European methods of tillage and ploughing, to the modern methods of no-till and conservation farming.
As early as the 1900s, plant breeders were working on developing new strains of wheat suited to the Australian climate. Improved knowledge of plant phenology – the life cycle of a plant – has enabled farmers to determine the most suitable planting and flowering times to optimise their limited water supply.
In the 1930s, farmers started to use ‘ley’ pastures, where legumes and clover are planted to overcome problems with weeds that would grow in otherwise fallow fields. The legumes also improve the nitrogen content of the soil, providing nutrients for subsequent grain crops. Additionally, these fields provided pasture for sheep, giving rise to a mixed farming method that diversified the farmers’ output, and improved resilience.
Even with the establishment of the ley pastures, the repeated cycles of crop residue burning, cultivation and ploughing that were required to eradicate weeds and prepare seed beds resulted in the deterioration of soil quality over time. Erosion was another big problem.
The 1970s saw the development of herbicides, chemical controls which killed the weeds, meaning manual weed management was no longer required. This significantly helped to increase farm yields. Effective weed control during fallow periods also helps to ensure sufficient reserves of water in the soil at planting times. Old crop residues are now left in place, and they form a mulch layer that helps protect the soil from the impact of raindrops and erosion, retain soil moisture and maintains hospitable soil temperatures for new seedlings. Planting ‘break crops’ of legumes, canola or lupins in between successive crops of wheat helps to reduce the transmission of pests and disease from one crop to the next. These crops also help to improve the nitrogen content of the soil, and also typically leave a smaller amount of residue, making the subsequent seed planting easier.
As part of the continuing shift to conservation farming, new harvesting and seed spreading machinery was also developed that enabled farmers to effectively process the old crop residues and plant new seeds through the crop detritus left on the fields. Other new management techniques include traffic control, where all machinery driving through the fields is kept along the same tracks, which keeps compaction from tractor tyres to an absolute minimum, along with improving fuel efficiency. GPS-guided planting techniques enable farmers to sow seeds in between the rows of previous years’ crops. Farmers are now able to generate digital maps of soil condition and yield and assess which areas of their fields may need preferential application of fertilisers or specific management treatments.
More recent advances in plant breeding have led to the development of plant varieties with longer coleoptiles, the part of the plant shoot that sprouts up to the soil surface. This means the seeds can be sown deeper and access water deeper in the soil.
The way that Australian farmers have transitioned from the traditional European farming techniques of tillage and ploughing to the modern methods of conservation farming illustrates the Australian agricultural sector’s capacity for adaptation. Australia is currently a world leader in the new innovative strategies involved in conservation farming, with nearly 70% of all arable land in Australia devoted to conservation farming methods. Climate change will present challenges to Australian agriculture, but Australian farmers have a proven track record in effective adaptation and application of innovative approaches to continually improve agricultural outcomes (see From dust bowls to food bowls - the conservation farming revolution for more about conservation farming, and Nova - Feeding the future for more about sustainable agriculture).
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Posted May 2013.