Farm dams a climate risk
Deakin study’s greenhouse gas surprise
WORLD- FIRST research conducted on farms around the region has found greenhouse gas emissions from farm dams are a significant contributor to man-made climate change.
And researchers say emissions could be slashed significantly with targeted changes to farming practices.
The Deakin University study sampled agricultural dams, and found Victoria’s dams produced the equivalent to the carbon dioxide emissions of 385,000 extra cars on the state’s roads.
The research was funded and carried out in collaboration with the Corangamite Catchment Management Authority, and used dams between Geelong and Ballarat.
Carbon dioxide and methane emissions from other water bodies, such as lakes, wetlands and reservoirs have been well studied, but “the emissions of highly abundant, small-scale agricultural dams have until now remained unknown”, lead author Quinn Ollivier, a PhD candidate at Deakin’s Blue Carbon Lab, said.
Mr Ollivier said while his study found farm dams had one of the highest emissions per square metre of all freshwater ecosystems, they were not currently accounted for in any greenhouse budgets.
“We found that nutrient management in farming areas would result in a major reduction in CO2-equivalent emissions, so this is an enormous opportunity for government to work with landholders,” Mr Ollivier said.
“Landholders may be able to reduce emissions by something as simple as re-plantation of native plants along dam edges. This could help to reduce the nutrients entering the dam and therefore the greenhouse gases coming out.”
Emission rates were significantly higher in livestock-rearing farm dams when compared to cropping farm dams.
“We estimate that by reducing nitrate nutrient levels by 25 per cent — through activities like minimising excess fertilisation and containing animal effluent — we may be able to reduce the emissions of some farm dams by up to half.”
Freshwater ecosystems, such as farm dams, play a significant role in global carbon cycling through the breakdown of organic material and the release of greenhouse gases.