Farm dams: How small changes can reduce carbon emissions

An untapped resource can reduce on-farm carbon emissions. See how you can make the changes.

Ecologist Dr Martino Malerba with dairy farmer Glenn Duncan at Glenn's dam. Supplied: Melbourne Water

An unexpected discovery in 2018 has led researchers to what they say is an “untapped resource” for reducing carbon emissions on Australian farms.

Deakin University’s Blue Carbon Lab “stumbled across” high greenhouse gas emissions from farm dams three years ago, and is now hoping to develop guidelines that would allow farmers to achieve carbon credits for better managing dams in the future, Deakin University ecologist Dr Martino Malerba said.

Despite their small size, on-farm dams are high emitters of the greenhouse gases, emitting four times more methane than natural water bodies, Dr Malerba said.

But by making a few simple changes, the researchers found farmers can radically reduce methane emissions from dams.

The “key piece of the puzzle” to drive down emissions was to increase the amount of oxygen in the water, Dr Malerba said.

The researchers found that by increasing plant life in and around dams, they could reduce nitrogen and phosphorous levels in the water, allowing oxygen to increase, and cutting methane emissions by 20 per cent.

And with an estimated 1.75 million farm dams around Australia, reducing the emissions they produce could have a big impact, Dr Malerba said.

The interventions they propose are simple: fencing dams, introducing vegetation and installing troughs for cattle.

For third generation dairy farmer Glenn Duncan, reduced carbon emissions were an “unexpected bonus” to a change that radically improved his water quality and increased biodiversity on his property.

Mr Duncan fenced off his dam with funding from Melbourne Water, and has since seen birds and wildlife flock to the property and water quality become much clearer.

“The problem is that when cattle walk through waterways they disturb the soil. They cause huge problems with sediment,” he said.

“Reducing carbon emissions, protecting waterways and preventing erosion all tie together,” he said.

But now that researchers have identified how to reduce emissions from dams, they are facing another challenge, Dr Malerba said.

The research is so new that the National Greenhouse Gas Inventory in Australia doesn’t include emissions from farm dams. “It’s just not on their radar,” Dr Malerba said.

To date no guidelines exist to attribute carbon credits to better managing farm dams, but Dr Malerba said, if guidelines could be established, he estimated farmers could earn between $2000 and $4000 in carbon credits for better managing dams.