Composting and anaerobic digestion obviously offer many benefits – they reduce pressure on landfill, create soil enhancers and, in the case of AD, even produce energy. And now, as Australian pioneers are finding, they could also play a role in a process of carbon sequestration. The breakthrough comes from Vital Resource Management (VRM), a Queensland-based organisation that produces biotech formulations that are used in both land and waste management. VRM had been using composting accelerants and stabilising agents in managing organic waste for over a decade, but around 2002 decided to take its work in this area further.
Managing Director Ken Bellamy explains that carbon sequestration reduces methane emissions and keeps the carbon locked in the soil: “In the soil, photosynthesis happens by light being captured 
into a phosphorus compound, which in layman’s terms you could think of as a type of fuel,” he explains. “The light is captured into a fast-burning fuel. The bacteria then use that fuel to capture carbon dioxides from the air to make a sugar which is a second-level fuel.”
Bellamy started off using other nutrients for the process but soon alighted on utilising organic waste. “We were looking for a medium and it was very obvious that it should be something that was cost-effective on a large scale. We needed it to be something that was organic based so we didn’t have to synthesise it. Also it had to be cheap, and recycled waste is very cheap.”
And this is where the ‘City to Soil’ programme being trialled by the New South Wales government comes in. Organic waste is collected from households in several towns in New South Wales and taken to a waste recovery site before being delivered to farmers participating in the scheme. The waste first goes through a process that Bellamy calls ‘no shred compost’: “That just means they collect the waste, spread it out, remove any residual contaminants and then inoculate that material with the cultures and then pile it up and leave it. That constitutes an incubation phase.
“Following that phase there is often a secondary incubation phase which involves feeding that material through an anaerobic digester and then producing out of the bottom of that a digestate. This would then be delivered to wherever it was going to be used, usually a farm. Then the cultures of bacteria and the nutrients that are collected and concentrated into that digestate act as a catalyst for photosynthesis in the soil. In effect, microorganisms capture carbon directly from the atmosphere and lock it into the soil.”
Bellamy explains that the process has been tested and trialled thoroughly. “We have seen some fairly dramatic increases in the content of carbon as a percentage of the mass of the soil. There have also been some very encouraging changes in the soil structure and content.” He predicts that by using such methods soil carbon could be increased by one per cent over a five-year period. A one per cent increase equates to the removal of 55 tonnes of CO2 per hectare.  
VRM insists that its technology can work in a range of soil types and suggests that Britain could be an early adopter of this system: “We’re really excited by what’s there in the UK. There is a real basic understanding there that recycling is first cab off the rank if you want to look at how to manage your carbon footprint.
“The management of climate change is really a social undertaking. It’s something that we should all do together. It’s people recycling and doing it in their own backyards that presents the way forward.”