Greenhouse gas abatement on southern Australian grains farms: Biophysical potential and financial impacts. (July 2017)

• Record Type: Journal Article
• Authors: Meier, Elizabeth A.; Thorburn, Peter J.; Kragt, Marit E.; Dumbrell, Nikki P.; Biggs, Jody S.; Hoyle, Frances C.; van Rees, Harm
• Is Part Of: Agricultural systems. Volume 155(2017)
• Page Start: 147
• Page End: 157
• Publication Date: 2017-07
• Subjects: Nitrous oxide emissions -- Soil organic carbon sequestration -- APSIM model -- Gross margins -- Global warming potential -- Carbon dioxide equivalent CO2e; Agricultural systems -- Periodicals; Agriculture -- Environmental aspects -- Periodicals; 338.16
• DOI: 10.1016/j.agsy.2017.04.012
• Languages: English
• ISSNs: 0308-521X

Abstract

Abstract: The agricultural sector generates a substantial proportion of global greenhouse gas (GHG) emissions through emissions of carbon dioxide (CO2 ) and nitrous oxide (N2 O). Changes to agricultural practices can provide GHG abatement by maintaining or increasing soil organic carbon (SOC) stored in soils or vegetation, or by decreasing N2 O emissions. However, it can be difficult to identify practices that achieve net abatement because practices that increase SOC stocks may also increase N2 O emissions from the soil. This study simulated the net on-farm GHG abatement and gross margins for a range of management scenarios on two grain farms from the western and southern grain growing regions of Australia using the Agricultural Production Systems sIMulator (APSIM) model. The soils and practices selected for the study were typical of these regions. Increased cropping intensity consistently provided emissions reductions for all site-soil combinations. The practice of replacing uncropped or unmanaged pasture fallows with a winter legume crop was the only one of nine scenarios to decrease GHG emissions and increase gross margins relative to baseline practice at both locations over the 100-year simulation period. The greatest abatement was obtained by combining this practice with an additional summer legume crop grown for a short period as green manure. However, adding the summer legume decreased farm gross margins because the summer crop used soil moisture otherwise available to the following cash crop, thus reducing yield and revenue. Annual N2 O emissions from the soil were an order of magnitude lower from sandy-well-drained soils at the Western Australian location (Dalwallinu) than at the other location (Wimmera) with clay soil, highlighting the importance of interactions between climate and soil properties in determining appropriate GHG abatement practices. Thus, greatest abatement at Dalwallinu was obtained from maintaining or increasing SOC, but managing both N2 O emissions and SOC storage were important for providing abatement at Wimmera. Highlights: On-farm GHG abatement available in grain cropping systems Greatest GHG abatement available from increased cropping intensity Profitable abatement from green manure legume replacing unimproved pasture/fallows Climate-crop-soil hydrology interactions determined potential abatement. Understanding trade-offs in GHGs essential for identifying abatement tactics