Read at : http://www.dpi.nsw.gov.au/research/updates/issues/may-2007/soils-offer-new-hope
Soils offer new hope as carbon sink
The huge potential of agricultural soils to reduce greenhouse gases and increase production at the same time has been reinforced by new research findings at NSW Department of Primary Industries’ (DPI) Wollongbar Agricultural Institute.
Trials of agrichar - a product hailed as a saviour of Australia’s carbon-depleted soils and the environment - have doubled and, in one case, tripled crop growth when applied at the rate of 10 tonnes per hectare. Agrichar is a black carbon byproduct of a process called pyrolysis, which involves heating green waste or other biomass without oxygen to generate renewable energy.
Tim Flannery, Australian of the Year and renowned scientist, conservationist, writer and explorer, is a major advocate of agrichar and pyrolysis.
In The Bulletin magazine, Flannery recently ranked “fostering pyrolysis-based technologies” fourth among his five steps for saving the planet, because they convert crop waste into fuel and agrichar which can be used to enhance soil fertility and store carbon long-term.
NSW DPI senior research scientist Dr Lukas Van Zwieten said soils naturally turn over about 10 times more greenhouse gas on a global scale than the burning of fossil fuels.
“So it is not surprising there is so much interest in a technology to create clean energy that also locks up carbon in the soil for the long term and lifts agricultural production,” he said.
The trials at Wollongbar have focused on the benefits of agrichar to agricultural productivity.
“When applied at 10t/ha, the biomass of wheat was tripled and of soybeans was more than doubled,” said Dr Van Zwieten.
“This percentage increase remained the same when applications of nitrogen fertiliser were added to both the agrichar and the control plots.
“For the wheat, agrichar alone was about as beneficial for yields as using nitrogen fertiliser only.
“And that is without considering the other benefits of agrichar.”
Regarding soil chemistry, Dr Van Zwieten said agrichar raised soil pH at about one-third the rate of lime, lifted calcium levels and reduced aluminium toxicity on the red ferrosol soils of the trial.
“Soil biology improved, the need for added fertiliser reduced and water holding capacity was raised,” he said.
The trials also measured gases given off from the soils and found significantly lower emissions of carbon dioxide and nitrous oxide (a greenhouse gas more than 300 times as potent as carbon dioxide).
NSW DPI environmental scientist Steve Kimber said an added benefit for both the farmer who applies agrichar and the environment is that the carbon in agrichar remains locked up in the soil for many years longer than, for example, carbon applied as compost, mulch or crop residue.
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Visit www.bestenergies.com or contact Dr Lukas Van Zwieten or Steve Kimber, Wollongbar, (02) 6626 1200.
- Phil Bevan
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