Greenhouse gas mitigation potential and profitability of practices on Australian grain farms

Abstract

Australian farm owners are being encouraged to mitigate emissions of greenhouse gases such as carbon dioxide (CO2) and nitrous oxide (N2O). However, trade-offs exist between mitigation strategies as practices that sequester carbon (hence reducing CO2 emissions) may increase N2O emissions. Further, the amount of CO2 (via carbon sequestration) or N2O emitted may change with time and vary with location characteristics including weather and soil type. In this study the net global warming potential and financial effect of on-farm practices designed to abate greenhouse gas emissions was assessed for a case study farm in the Western Australian wheatbelt (low carbon soil-low rainfall environment). The usual farm management formed the baseline against which alternative scenarios aimed at mitigating greenhouse gas production were evaluated for a 100 yr period. Simulated yield and nitrogen fertiliser rates from the APSIM model were used to estimate the annual gross margin. Scenarios that involved retention instead of burning stubble or adding additional organic matter decreased the net global warming potential without reducing gross margins. Scenarios that used a lower nitrogen fertiliser rate than the baseline resulted in a decrease in yield and profitability with little effect on net global warming potential.