Last updated June 7, 2018 at 10:07 am
Follow the unlikely heroes on a quest to deliver a genuine climate change solution.
A still from Grassroots documentary
Award-winning documentary Grassroots follows the story of a group of scientists, agronomists and farmers on a quest to trap and store carbon in soil.
It could be the only way to avert the global warming crisis – reducing emissions simply isn’t enough to avoid excessive warming.
If we want to meet our Paris Climate Agreement obligations to avoid temperature rise of 2 °C by the end of the century, then we need to avoid pumping out more CO2, while at the same time figuring out ways to remove CO2 from the atmosphere and store it, so it cannot cause further environmental problems.
Geological Carbon Capture and storage
One of the largest scale trials of carbon capture and storage (CSS) in Australia is the Gorgon gas project in Western Australia.
This was expected to be the largest long-term carbon dioxide storage project in the world, with the plan to inject 3-4 million tonnes of CO2 into long term underground geological storage each year.
Earlier this month the project was reported to have released millions of tonnes of CO2 into the atmosphere rather than injecting it underground, due to reported issues with the injection system.
“Despite a lot of investment in demonstration projects, there are no large-scale carbon capture and storage projects currently operating in Australia nor are there any realistic plans on the table to do so,” says Brett Bryan, Professor of Global Change, Environment and Society at Deakin University who developed a Land Use Trade-Off model used by CSIRO in modelling trajectories for Australian land use up to 2050.
“I am a long way from being convinced that converting our aquifers into sparkling mineral water does not simply create an underground catastrophe waiting to happen.
“Most trials of carbon capture and storage to date have failed,” says Bryan.
Environmental carbon capture
An alternative way to reduce atmospheric CO2 is to capture it into biomass by planting trees or increasing the amount of carbon in the soil.
“Trees are great machines for sucking carbon dioxide out of the atmosphere and converting it into habitat for our endangered animal species, reducing soil erosion, and making the place cooler and prettier,” Bryan says. As long as we are careful that they don’t take out our best farmland, trees are a good solution.
But another solution may lie under the soil surface. Soil fungi – or endophytic fungi – live in symbiosis with plants, and recent CSIRO studies have shown the capacity for specific strains of fungi to improve the levels of soil carbon.
They can do this by producing the carbon-based pigment melanin.
The cyclic structure of the melanin molecule, and the anaerobic conditions in the way the fungi aggregate, holds carbon in the soil, potentially as a long-term storage solution.
So spiking crops with an inoculation of this fungi could improve not just carbon capture, but the health and productivity of the soil.
“It probably also makes soils healthier, more fertile, and returns greater profits to farmers. All these are good things for sustainability of our food production systems.” Says Bryan.
Increasing soil carbon is win-win
“Primarily carbon stores water,” explains agronomist Guy Webb, who features in the Grassroots documentary and is co-founder of the not-for-profit research organisation Soil C Quest.
“It does lots of other functions in terms of nutrient holding capacity but soil carbon stores moisture and that’s well established” he says.
Australian agriculture takes place in a lot of marginal areas that can face challenges with soil quality and water availability.
In Australia 39% of soil organic carbon was lost from farmed land between 1860 and 1990. If that trend continues, it threatens long-term ability of farmers to grow our food.
Webb is excited about the process of using melanised endophytic fungi to inoculate seeds for crops to improve soil carbon.
He likens it to the inoculation of pulse and legume crops with Rhizobia bacteria that fix atmospheric nitrogen, a common agricultural practice. Farmers in Australia have recognized the benefit of this for a century.
The Rhizobia bacteria take nitrogen from the air and turn it into a form plants can use, to improve crop growth and yield. Instead of nitrogen, the endophytic fungi would take carbon from the air and fix it into the soil.
“This technique can empower farmers to easily and economically store carbon in their soils” says Webb.
The project is still in the development phase “We hope within 12 months to have a working prototype,” says Webb.
“We’ve just finished a glasshouse project in Orange looking at a couple of different isolates and measuring soil carbon.
“We’re testing some new isolates that we’ve bioprospected. We’re still very cognizant it’s a huge project with lots of avenues to explore with a long way to go before we have a robust inoculum, but there’s lots and lots of interest.”
Beyond the benefits to farmers, the potential to be a significant avenue for carbon capture to mitigate climate change is a real possibility.
Although the total amount of carbon stored per hectare is not likely to be huge, multiplying it by the vast areas of farmland could have an impact.
“It’s upwards of half a billion hectares we’re farming as a species. Soil is our largest terrestrial carbon sink, we need to know how to engage it if we’re going to make a difference,” says Webb.
