A new low-tech development in soil management may pave the way for no genetically modified food and bypasses fertiliser and pesticide use.
South Australia is the driest state in the world’s driest inhabited continent, and stands to be negatively impacted in the future by climate change. Issues facing its agriculture sector include nutrient-deficient soils with low fertility and poor water-holding capacity. Often these are compacted, inhibiting root growth. Soil quality tends to diminish with depth, and the root zone generally goes down no further than ten centimetres.
In recent years, the state government has been partnering with academia and the sustainable farming sector in agricultural trials that show great promise not only for South Australia but also other Australian regions and dryland areas overseas.
In 2014, three trials were started as part of the New Horizons program, all chosen for their sandy soils. One is at Karoonda in the Mallee region, hosted by the Mallee Sustainable Farming Group. Another has been taking place at Cadgee, near Naracoorte in the south-east of the state. On the Eyre Peninsula, the third has been running at Brimpton Lake, near Mitchell.
New Horizons involves the addition of clay, organic matter and nutrients at a range of soil depths, going down to 50 centimetres. Clay is particularly useful in holding water and aiding nutrient absorption, maximising the beneficial effects from rainfall.
Unfortunately, natural clay is typically found in a layer starting about 30 centimetres down, well below the top 10-centimetre root zone. A set of mechanical shovels attached to the back of a tractor, known as a spader, can get down into the clay, stirring it up and mixing it with the sandy soil above. The resulting mixture creates pathways for roots to extend down to the 50-centimetre mark, facilitating the growth of healthier plants.
Expected benefits include :
- A significant increase in productivity, and therefore farmers’ profits.
- More efficient use of water.
- Improved fertility.
- Long-term carbon storage.
- Reduced soil erosion risk.
Yield increases have so far been very impressive, with 2014 trial results ranging from 111-318 per cent, and the best results obtained in the Mallee region. The following 2015 season showed a 74-226 per cent improvement, with figures depressed by lower than average rainfall.Another benefit was to see germination one week earlier, an advantage when the soil is drying up at the end of the dry season.
Primary Industries and Regions SA is in the process of setting up a paddock-scale demonstration site at its Struan Research Centre, also close to Naracoorte. Organic matter sources will include locally available compost and bean stubble straw. The results from New Horizons stand to benefit about 40 per cent of the state’s broadacre farming area with poor soils, but before it is rolled out to interested farmers, researchers want to be more confident about the techniques, a guarantee of increased yield, and the economics of soil treatment. Despite being expensive, it is hoped that the initial investment will quickly be recouped.
Once underway, South Australia’s authorities hope that soil modification will be a way to reverse population loss from small rural centres by giving them an economic injection that stands to boost the whole local economy.
However, not everybody is happy with these breakthroughs. Grain Producers SA is an advocate of genetically modified food technology and objected to comments by Agriculture Minister Leon Bignell that the impressive yield increases dwarf the promised benefits from genetically modified food crops, and therefore make the crops unnecessary.
South Australia has a moratorium on genetically modified food production that is running until 2019, and the government has stood firm against pressure to lift it. For canola growers, GM-free oil attracts a price premium, with Australia being the world’s sole supplier. New Horizons is an important breakthrough due to its environmentally sound low-tech approach, and through bypassing extra fertiliser and pesticide use that damages the long-term viability of the soil.
New Horizons www.pir.sa.gov.au/major_programs/new_horizons
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