Global warming potential of wheat production in Western Australia: a life cycle assessment

Abstract

This study presents a greenhouse gases (GHG) life cycle assessment of one tonne of wheat transported to port in south-western Australia; including emissions from pre-farm, on-farm and post-farm stages. The pre-farm stage included GHG emissions from agricultural machinery, fertiliser and pesticide production. The on-farm stage included GHG emissions from diesel use, liming, and nitrous oxide (N2O) emissions from N fertiliser applications. The post-farm stage included grain storage and transportation to the port. GHG emissions decreased from 487 to 304 kg CO2-equivalents when we used regional specific data for N2O emissions instead of the IPCC default value for the application of synthetic N fertilisers to land (1.0%).. Fertiliser production in the pre-farm stage contributed significantly (35%) to GHG, followed by the on-farm CO2 emissions (27%) and the emissions from transportation of inputs and the wheat (12%). Nitrous oxide emissions from paddock represented 9% of the total GHG emitted. We recommend utilizing regionally specific data for soil N2O emissions, rather than international default values, when assessing GHG for agricultural production systems.