A TRIAL investigating cattle performance on rehabilitated mined land was initiated by Queensland-based miner New Hope Group to improve the company's rehabilitation techniques.
After more than five years of collecting data at its New Acland Mine north-west of Oakey, the grazing trial has helped New Hope to improve its rehabilitation efforts and increase productivity of its rehabilitated mined land.
The trial indicates that cattle grazed on rehabilitated mine land can perform as well as herds in regular pastures.
During the progression of the study, they also learned cattle on their rehabilitated sites could sometimes outperform their counterparts in the non-rehab paddocks, and were able to use the information to finetune their future rehabilitation techniques - an added bonus of the experiment was that it helped the company become the ABA100 Winner of the Australian Business Award for Sustainability last year.
Now, New Hope is a leading example for sustainable mine rehabilitation, as touted by Queensland Resource Council chief executive Ian Macfarlane at the recent Rural Press Club meeting.
This week the Rural Weekly chatted to Outcross director Tom Newsome and University of Southern Queensland scientist Dr John Bennett, to learn about the methodology behind the grazing trial.
Outcross, which is a livestock consultancy business, was hired by New Hope to conduct the independent study on its grazing land, focusing on cattle performance, and USQ scientists looked after the research on soil quality.
Mr Newsome has worked on the project since its beginning in 2011.
"So we have been working with New Hope for six years now. Initially we did a pilot trial for six months, then we looked at the information that came out of the pilot in order to help us design the actual main project of the research," he said.
Mr Newsome was quick to stress they entered the study knowing there would be critical eyes looking for holes in their research.
"We tried to do everything in the best practice methodology so that we could limit the amount of criticism of our research design," he said.
The grazing trial uses angus cattle, mostly coming from the same bloodline and from a single vendor, which graze across fenced-off land that was rehabilitated, from two years ago and right up to 15 years previously. The study imitated a rotational grazing system, Mr Newsome said.
Each beast was performance measured from the time they were inducted into the trial until they were sent to the abattoir for processing.
"We measured their performance, between 12 months to two years, on grass, as well as collecting feedlot performance information and information at the abattoir, with respect to compliance specifications, assessment data and eating quality through MSA systems."
Cattle were also tested for meat contaminants.
"This is what people in the community may be concerned about in regards to cattle grazing on rehabilitated mine sites," he said. "So the results from that was there were no abnormalities, in terms of potential contaminants - we effectively tested a list of all the possible contaminants.
"So we take liver samples and do the containment testing from the liver tissue, which is a more accurate way of doing it than blood testing."
Mr Newsome said the data collected indicated that grazing cattle on rehabilitated mine land was both viable and productive. There were eight occasions when cattle on rehab blocks performed better than those at the control site.
"That's not to say that it has always been the case, because the control has been the highest performing site on a few occasions as well," he said. "So I think it has been a very positive result, in terms of the environmental outcomes ... and in terms of the commercial grazing of rehab land if it's done well.
"As the trial goes on, we will be able to measure sustainability outcomes."
Dr Bennett said the soil results from New Hope's rehabilitated paddocks would be surprising to some.
"What we have seen across all of the rehabilitated sites is that nutrient wise, we are comparable to our control site," he said.
"We are not at the lower end of the range (of soil quality), which is what many people expected for these soils to be when they were rehabilitated."
Researchers ensured the experimental design of their study was rigorous by comparing data to the non-rehabilitated control site.
"We have also taken another 18 benchmark sites, so that's unmined land around the mine site, in which to compare where this control sits in the broader context of the region.
"So, once we have the results back from the rehabilitated land we can look at how they compared to the variables we see in the surrounding region.
"The focus we have had is largely in respect to soil structure and also nutrient movement and availability within the soil."
So far the research has also indicated there were no significant structural differences within the soil - but this is something Dr Bennett stressed needed more thorough research.
"So the soil has maintained its stability, these were non-dispersive stable soils to begin with, but the overall profile structure is destroyed when you remove the profile (with mining). Now, that structure doesn't regenerate in the short-term. We have seen some results of structural evolution, but you don't see the naturally occurring structure.
"So what we have seen is the structure stability of the small soil aggregate is still stable ... but I feel we need more data."
Mr Newsome believed more mine companies would invest into their rehabilitation research, if there were more incentives.
"I think if the government supports these sorts of initiatives, in terms of providing pathways for ultimate relinquishment, then there is more incentive for other mining companies to go down this path of measuring their rehab and investing into their rehab," he said.
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