Managing carbon in livestock systems: modelling options for net carbon balance (TIAR)

Summary

This study examined the total greenhouse gas (GHG) emissions (tonnes of carbon dioxide equivalents; t CO2e) and GHG emissions intensity of lamb production (kg CO2e/kg dressed weight) of a prime lamb enterprise, located in the Northern Midlands of Tasmania. Using the FarmGas and Framework calculators the GHG emissions intensityof lamb production was estimated at 9.0 and 14.7 kg CO2e/kg dressed weight, respectively. Several management and genetic improvement abatement strategies were assessed. This included reducing the age of joining maiden ewe lambs to 7 months, increasing weaning rates either with or without changes to ewe numbers, improving ewe efficiency or extending ewe longevity. It was estimated that the adoption of these strategies alone could reduce the GHG emissions intensity of lamb production by between 3 and 12%.
​A stochastic modelling technique was adopted to account for the variation that exists in key emission factors when undertaking a deterministic assessment of GHG emissions. This provided an assessment of the confidence level around the mean result and furthermore, highlighted the emission factors which must be described more accurately to improve emissions estimations.  A review of currently available tools to determine their usefulness in estimating farm GHG emissions and changes in emissions resulting from changes in management practices is also provided.