While the race is on to discover and develop the most effective ways of reducing methane emissions in cattle, biochar is unlikely to be first in line if the findings of a CSIRO study are anything to go by.
CSIRO research scientist in the gut microbial team, Dr Gonzalo Martinez-Fernandez told a Western Queensland Beef Research committee meeting in Barcaldine in June that the biochars and doses tested in a project for Meat & Livestock Australia didn't offer methane abatement levels that would allow it to be classified as anti-methanogenic for commercial purposes.
There had been interest in biochars as an additive for ruminants because of their anti-methanogenic potential but results from studies in animals were limited and sometimes contradictory.
According to Dr Martinez-Fernandez, biochar, or charcoal made from slow-burning organic matter, had no effect in some studies while others showed effectiveness of between 20 and 40 per cent.
There was also interest in feeding biochar to cattle and sheep because soil health is improved when dung beetles distribute it through the soil.
The CSIRO study tested 14 different, unnamed biochars in five in vitro experiments to see what might be fit for purpose, eventually selecting the two best ones and giving cattle different doses to see what might maximise productivity and minimise emissions, and be incorporated into a palatable diet.
The cattle were put into respiration chambers for measurement purposes.
"Both the biochars we used were able to reduce methane between 8pc and 9 to 12pc, not as much as claimed by some studies," Dr Martinez-Fernandez said.
The variability was driven by the biomass type used, pyrolisis temperature, pre- and post-pyrolisis manipulation, and dose rate.
Then in grazing trials at Lansdown Research Station near Townsville, cattle were supplemented for 60 days.
The extent of the methane reduction under these conditions was lower than what had been measured in the in vitro tests.
"Further research will be required to identify a fit-for-purpose biochar suitable for grazing systems," Dr Martinez-Fernandez concluded.
"The successful candidate would require a much greater methane reduction than we observed under controlled feeding conditions to be suitable to be used as an anti-methanogenic supplement under grazing conditions.
"I am not sure if the MLA would have the appetite to continue investing in biochar."
WQ Beef Research committee member David Counsell said it was good to see producer dollars going towards solid research giving quantifiable outcomes.
Dr Martinez-Fernandez went on to say that in his opinion, there were other supplements that offered greater methane-reducing effects in extensive grazing systems.
The mini-forum tossed around the various benefits of feeding leucaena and desmanthus, and feed additives such as asparogopsis, questioning how much would be needed in a diet to be useful.
Dr Martinez said leucaena was a good legume but a methodology was needed to make it effective.
"The stage of the plant, the time of year means leucaena can produce more or less, which is another challenge," he said.
He told the forum that the issue with asparagopsis would be finding enough red seaweed to harvest to dry for feed.
"That will be a real challenge," he said.
IN OTHER NEWS:
Sally Gall
Based at Blackall, CW Qld, where I've raised a family, run Merino sheep and beef cattle, and helped develop a region - its history, tourism, education and communications. Get in touch at 0427 575 955 if you've got a story idea for me.
Based at Blackall, CW Qld, where I've raised a family, run Merino sheep and beef cattle, and helped develop a region - its history, tourism, education and communications. Get in touch at 0427 575 955 if you've got a story idea for me.
