The misconception of Australian agriculture being inefficient and unsustainable is deeply concerning for me. Images of dusty ploughed fields and dying sheep and trees are misleading. On the contrary, if there was an Olympics for conservation agriculture Australian farmers would win gold!
Far from being inefficient and unsustainable, Australia is leading the world in conservation agriculture techniques. Conservation agriculture which emerged from the “dustbowl” years of the 1930s is based on three key principles – minimal soil disturbance, permanent soil cover, and a diversity of plant species. I call it the three R’s – reduce tillage, retain crop residues, rotate crops.
Three developments brought Australian farming from the tillage-based agriculture that dominated from the 1800s up to the 1980s to the conservation farming revolution:
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The development of herbicides. These chemicals have been refined and are now effective at targeting specific weeds with minimal environmental impact. Before herbicides, farmers’ only option for weed control was ploughing the soil to kill the weeds and to prepare a seedbed for planting. Soils had to be ploughed repeatedly because every time it rained new weeds emerged.
The evolution of more effective and efficient machinery to sow through crop residue into undisturbed soil. Herbicides allowed crops to be grown without ploughing, but machinery designed to sow into soft, bare, cultivated soil had to be redesigned to sow into undisturbed soil and through a mulch of residue left from the previous crop. Farmers led the innovations in machinery to make this happen.
The introduction of broadleaf rotation crops (lupins, peas, canola) to underpin weed and disease control in conservation agriculture systems. Rotating crops is necessary for conservation agriculture. Weeds and diseases will build up in the residue and be carried from one crop to the next if the same crop is grown year after year. In addition, weeds soon become resistant to herbicides if the same herbicide is used repeatedly. By rotating the types of crop that grow, the diseases of one crop cannot build up and the types of herbicides used for the weeds can be changed each year. Legume rotation crops (peas and lupins) also make their own nitrogen which reduces the need for fertiliser.
But we didn’t stop in the 1980s.
Farmers can now manage their fields down to centimetre accuracy. Precision agriculture is continuing the revolution, introducing controlled traffic, zone management and in-crop sensing to improve farming systems’ efficiency and sustainability.
Controlled traffic is where farmers keep all of the machinery on the same tracks in the field (up and back instead of round and around) so that only those areas are compacted by the wheels. This reduces compaction on the field, reduces wasted spray and fertiliser due to overlaps, and makes the tractor much more fuel efficient because it is driving on harder soil. Better growth of crops in the un-compacted area compensates for the narrow tracks.
Harvesters can also stay on these tracks - with GPS guidance and an ability to measure crop yield on the run - can produce yield maps to show the farmer which parts of the field are performing better than others. Different amounts of fertiliser or other inputs can then be applied to the different zones, further increasing efficiency. Colour sensing monitors fitted to tractors can even sense how green the crop is and adjust the amount or fertiliser that is applied as the tractor is passing over the crop.
So it is now possible with GPS and optical sensing for farmers to deliver nutrients or herbicides exactly where they are needed in the paddock within a 2cm margin of error. This not only reduces costs to the farmer but reduces the impact of these chemicals and residues on the environment.
There are still many challenges for the future. These include managing herbicide resistant weeds that can emerge when the same herbicides are used repeatedly as the only form of weed control. Rye-grass is one of the most challenging weeds for no-till systems in Australia. Careful management - including rotating the types of herbicides that are used, destroying the seeds through collection at harvest time and growing vigorous crops that can out-compete the weeds - are all part of the integrated management required. Diseases that can be carried on crops residues and roots can also create problems, but selecting resistant varieties, rotating crops and judicious use of fungicides provide good control options.
Crop yield has doubled in the last 30 years under conservation agriculture systems. But there is still more scope to improve yields as there remains a considerable gap of 30-50% between the potential yield in experimental plots and what is being achieved on farms. Though some of this difference relates to pure economics and risk that farmers have to consider, new innovations to increase yield without higher risk are emerging.
We are breeding new varieties to take advantage of the conservation farming techniques, such as wheat varieties with longer coleoptiles to emerge through the mulch of stubble and vigorous shoots and roots to compete better with weeds. New rapid real-time environment and crop sensing technology will provide quicker analysis of soil and crop conditions and allow farmers to make more timely decisions about fertiliser and other inputs.
As much of the change to farming with conservation agriculture is in the soil, a new focus on root-soil biology research rather than on the above-ground parts of the plant may provide new ways to improve crop performance under these new conservation systems. Though soil improvements such as earthworms and organic matter are welcome, not all of the organisms that build-up are “crop-friendly”. We need to understand how to avoid the effects of the disease and inhibitory organisms while capturing the benefits of better soil.
Finally the “Holy Grail” for farmers – improving accuracy of weather and seasonal forecasting - is being made possible by information being gathered internationally about the ocean temperatures and how they influence our climate. Better forecasts allow farmers to better match crops and inputs to the seasonal condition. They can grow better crops with less input and reduce their financial risks as well as those to the environment.
Much of my research success can be attributed to the strong relationships I have developed over the years with farmers and farm consultants who are often first to alert us to interesting factors affecting their crops and the difficulties encountered when introducing conservation farming techniques. They are genuinely committed to preserving and improving their land and providing safe and nutritious food and we should be aware and proud of the world-leading revolution in conservation agriculture they have achieved in 30 years.
If you want to know more you can watch the public lecture I gave at the Academy of Sciences here or explore my work at CSIRO here.