Soil carbon presents significant opportunities, but it is hard-going

Eric Barker, 18/07/2023

The Fysh project at Mount Tom, near Gladstone, has become the fourth to receive carbon credits for sequestering carbon in its soil.

WHILE the Australian soil carbon industry is starting to get off the ground and credits are being issued, some of the ongoing challenges it will face were unpacked at a three-day conference which started in Brisbane this week.

Monday’s Soil Carbon Summit showcased some of the significant private investment soil carbon has attracted – with it being an opportunity to earn carbon credits and make developments to grazing operations at the same time.

The ongoing theme was that the Australian carbon market was going to be increasingly reliant on supply of soil carbon credits. Carbon Link’s Chris McCosker and Agriprove’s Matthew Warnken showed the opportunities with credits already being issued and more on the way.

The main catch is that they are long-term projects, requiring landholders to keep up certain activities and keep carbon in the ground for 25 years through droughts and any other events outside the producer’s control.

Queensland University of Technology Associate Professor Dave Rowlings said he also saw opportunities in soil carbon. However, he said producers needed to be aware of the 25 year ‘permanence’ period and the possibility of paying credits back if they lose carbon.

“Ultimately, carbon needs to stay in the ground for 25 years to prove that soil carbon increases have been the result of improved management,” Assoc Prof Rowlings said.

Dave Rowlings

“But this is the big challenge, because you can’t make producers wait for 25 years to be paid. So, they get paid in five-year increments, which is normally only one weather cycle.”

How much influence does management have?

Assoc Prof Rowlings has been measuring the influence of management changes to soil carbon using flux towers, which monitor the flows of CO2, and core samples.

“Flux towers are great pieces of technology, we can ignore the last 10,000 years of soil history and we can focus on the changes in CO2 with the change in management,” he said. “We are also using a paired approach with a control paddock so we can scientifically tease out any management impact from short-term seasonal conditions, something the carbon aggregators aren’t required to do”.

He showed the data from a project near Goondiwindi, which had measured significant increases in soil carbon.

“The increases we measured there are massive, they blow any other scientific numbers out of the window,” he said.

“It just shows our limited understanding of how dynamic these systems are and that there is a huge potential there. The question is, how much of it was management, how much of it was to do with the record rainfall following three La Ninas in a row and how can we separate the two?”

Most of the scientific literature on soil carbon has been about the top 30cm of the soil and the soil carbon industry believes a lot of the changes come at depth – with Carbon Link’s latest projects measuring down to 1.2m and recording that 44pc of its increase was at depth.

Assoc Prof Rowlings was asked about this in a panel session, to which he said adding depth added a layer of complication for scientists and carbon aggregators using soil coring.

“Things get messy when you get down to those depths, you have a lot of carbonates and you need to remove them which creates another source of error. There’s also more gravel and the bulk density increases,” he said.

Rafael Wood

“The reality is that 90pc of the activity happens between 0 and 30cm, it is where most of our nutrients are and it is where our root turnover is. We have measured to depth before, but the reason that most of the science has been done from 0 to 30cm is because that is where the action is.”

Assoc Prof Rowlings put out a plea to the carbon developers in the room and the Clean Energy Regulator to make the soil carbon data they are generating publicly available so the scientific community can increase its knowledge on how much management can influence soil.

Buyers aware of the challenges

Market Advisory Group’s Raphael Wood said many soil carbon buyers were aware of the challenges soil carbon presents.

“You need to get a good handle on how many ACCUs per hectare per anum and the volatility of that – note that it can fluctuate, and it almost certainly will with climatic conditions and land management practices,” Mr Wood said.

“Investors and buyers of ACCUs are worried about this, they want some assurance that you are going to produce what you say you are going to produce if you are looking for long-term forward contracts.

“I think when it all settles down you should be getting a premium for soil carbon credits, it is high integrity and can create a lot of supply. I would just say to do your homework and modelling of forward pricing like any other commodity.”









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