"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.
"We broadly categorise carbon in the soil as being labile (liable to change quickly) or stable depending on how quickly they break down and convert into carbon dioxide," he said.
"Labile carbon like crop residue, mulch and compost is likely to last two or three years, while stable carbon like agrichar will last up to hundreds of years.
"This is significant for farmer costs because one application of agrichar may be the equivalent of compost applications of the same weight every year for decades.
"For the environment, it means soil carbon emissions can be reduced because rapidly decomposing carbon forms are being replaced by stable ones in the form of agrichar."
Unfortunately, agrichar is not widely available. BEST Energies Australia, a company involved with NSW DPI in the trials, has a pilot plant at Gosford which is producing minimal amounts for research purposes.
"We are hoping the technology will take hold and pyrolysis plants will be built where there is a steady stream of green or other biomass waste providing clean energy that is carbon negative," Dr Van Zwieten said.
"But until pyrolysis plants are up and running, the availability of agrichar for
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Contact: Joanne Finlay
joanne.finlay@dpi.nsw.gov.au
61-263-913-171
New South Wales Department of Primary Industries
31-May-2007