University of Sydney scientists to develop easy-to-measure parameters for monitoring carbon dioxide and methane fluxes

Technical officer at the University of Sydney Milad Begheri Shirvan spoke on day two of the Dairy Research Foundation Symposium.

Mr Shirvan's primary expertise is in employing technologies and techniques for monitoring greenhouse gases in pastures and livestock-based systems.

Soil organic methane fluxes in pastures are influenced by a range of environmental factors, including grazing, soil type, soil moisture, soil temperature, and fertiliser application, among other pasture management practices, and can change over time.

Monitoring soil carbon sequestration can be a time-consuming and expensive process.

So scientists are attempting to develop easy-to-measure parameters for monitoring carbon dioxide and methane fluxes to determine soil organic carbon and soil carbon sequestration on-farm.

"We are measuring from pastures and soils as a whole ecosystem," Mr Shirvan said.

"At the same time, we have plans to monitor soil moisture, temperature and biomass.

"Then we can find the most effective parameter to predict fluxes."

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So far, the research has incorporated varying pasture and soil types.

The study involving kikuyu pasture saw eight study chambers in total, with four located in the grazing area while the other four were located in a non-grazing area.

The study chambers were moved to different parts of the paddock at intervals.

The pasture was mulched in December 2021, grazed and fertilised in January 2022, and further grazed in February 2022.

In the grazed are, carbon fluxes were measured for 19 and 10 days after the first and second grazing event, respectively.

"We found carbon uptake was higher in the grazed area compared to the ungrazed area in January," Mr Shirvan said.

"Methane emissions were higher in grazed areas in January but decreased over time.

"When the grazing and slashing occurred together, there were more changes in the paddock and pasture, resulting in less carbon uptake.

"Therefore, the changes in carbon uptake are related to grazing management.

"In conclusion, moderate grazing can improve pasture production and increase soil organic carbon."

The research on carbon dioxide and methane fluxes is ongoing, and researchers have plans to examine various pastures across several years to monitor changes to soil carbon sequestration based on variable environmental factors.