Markets for organic grains are booming but, depending on the approach, mixed farming with organic and biodynamic systems is less productive and profitable than with conventional methods.
These are some of the findings from long-term trials established at the University of Adelaide's Roseworthy Campus in 1989, and supported by growers and the Federal Government through the GRDC.
The trials also pointed to strategies for improved performance in organic systems and indicated that well-managed conventional farming systems, using best recognised practices, may have no negative impact on the soil.
Gross margins after eight years of trials revealed that conventional farming performed 50 per cent better than the organic option, allowing for a 20 per cent premium above the market price for the organic product.
"The low economic returns from sheep grazing pastures over the period of the trial were a major impediment to the productivity and financial viability of the alternative systems, leading to pastures being dropped from rotations as the research progressed. This had an impact on weed and nutrient management within these systems," said project leader Chris Penfold.
He said Asian demand for organic grains is increasing rapidly, and some Australian organic and biodynamic farmers will capitalise on those markets.
Currently the global market for organic foods is expanding at 25 per cent, with premiums for certified product.
Animal manure still the key to fertility
Perhaps surprising to some, the trial showed soil fertility declined under both organic and biodynamic systems, nitrogen (N) and phosphorus (P) levels falling under biodynamic treatments and N under organics after eight years of trials. The conventional farming treatment had 125 per cent more available P than the biodynamic treatments. In the integrated system, phosphorus levels remained the same, while high levels of productivity were maintained.
The organic and biodynamic treatments abided by the requirements of the National Association for Sustainable Agriculture Australia (NASAA) and the Biological Farmers of Australia Grade A certification standard. These standards set allowable inputs and exclude the use of synthetic fertilisers and pesticides.
The integrated and conventional treatments combined minimum tillage/direct drilling 'best practice' methods with pesticides and herbicides. The integrated method used municipal sewage sludge as the principal fertiliser source and the conventional method used synthetic fertilisers.
The trial is a comparison of farming systems, allowing flexibility within rotations. Crop selection is influenced by estimated profitability, predicted weed and pest problems, soil nutrient status and the guidelines established for each system.
The 16 ha trial site has duplex alkaline soils and basal available phosphate of 37 mg/kg. Sustainability was measured from the chemical, physical and biological status of the soil along with the productive and economic performance of each treatment.
Mr Penfold suggested the principal reason for the fertility falls in organic and biodynamic treatments was the high cost of non-chemical fertiliser sources of N and P, making farmers reluctant to apply them at replacement rates or higher.
Ideally, he says, organic farming requires a ready source of composted manure, allowing the application of the large quantities of nutrient required in modern farming. While organic manure can be purchased, transport costs are often a barrier.
Think green manure and lucerne
Mr Penfold says the research points to ways of improving organic farming systems, in particular the potential of green manures to play a larger role in organic rotations.
"Ley periods are essential in organic farming systems, for both weed control and nitrogen fixation, but pastures are likely to be a financial liability as long as premiums for organically produced meat and wool remain elusive," he says. Green manures may be the answer so long as phosphorus does not limit the legume productivity.
"As well as green manures, lucerne either intercropped or as a phase in an organic rotation would improve the water utilisation of the whole farming system. Novel tillage, rotation and weed management systems may be necessary in organic farming."
Mr Penfold says nutrient supply—particularly of P — will remain a concern for organic farming and currently available, commercial microbial activators may have potential to increase the availability of soil-bound phosphates.
Overall, Mr Penfold said more farmers are seeking a 'best of both worlds' approach by implementing some alternative farming practices with conventional systems.
"Many farmers are not comfortable with the high-input approach to farming and are looking for information on farming systems that suit their farming philosophy, while remaining profitable and ecologically sound," he said.
|1988||Regenerated pasture||Regenerated pasture||Regenerated pasture||Regenerated pasture|
|1989||Oats/medic for hay||Oats/medic for hay||Oats/medic for hay||Wheat|
|1990||Wheat crop mulched prior to flowering||Legume-based pasture||Legume-based pasture||Peas|
|1991||Oats/medic/vetch/faba bean green manure||Oats/vetch for hay||Legume-based pasture||Legume-based pasture|
|1993||Chickpeas||Safflower||Faba beans||Faba beans|
|1994||Cereal rye/vetch||Oats/vetch||Wheat (hard)||Wheat (durum)|
|1995||Faba beans||Oats/vetch||Faba beans||Canola|
Program 3.4.2 Contact: M r Chris Penfold 08 8303 7735