Schwenke, Graeme D

Brock, Philippa M

Haigh, Bruce M

Herridge, David F

2018

To contribute to national greenhouse gas emissions (GHG) reduction targets, grain growers need strategies that minimise emissions associated with grain production. We used life cycle assessments (LCAs) with field-measured production inputs, grain yields and proteins, legume nitrogen (N₂) fixation, and soil nitrous oxide (N₂O) and methane (CH4) emissions, to explore mitigation strategies in 3-year crop sequences in subtropical Australia. The sequences were: canola plus 80 kg/ha fertiliser nitrogen (80N)-wheat 85N-barley 65N (CaNWtNBaN), chickpea 0N-wheat 85N-barley 5N (CpWtNBa), chickpea 0N-wheat 5N-chickpea 5N (CpWtCp), and chickpea 0N-sorghum 45N (CpSgN). We also assessed the impacts of split fertiliser N application and urea coated with DMPP, a nitrification inhibitor, on the LCA for the CaNWtNBaN sequence. Total pre-farm plus on-farm GHG emissions varied between 915 CO₂-e/ha (CpSgN) and 1890 CO₂-e/ha (CaNWtNBaN). Cumulative N₂O emitted over the 3-year study varied between 0.479kg N₂O-N/ha (CpWtCp) and 1.400 kg N₂O-N/ha (CaNWtNBaN), which constituted 24-44% of total GHG emissions. Fertiliser production accounted for 20% (CpSgN) to 30% (CaNWtNBaN) of total emissions. An extra 4.7 kg CO₂-e/ha was emitted for each additional kg N/ha of applied N fertiliser. Three-year CH4 emissions ranged from 1.04 to 0.98 kg CH4-C/ha. Split N and DMPP strategies could reduce total GHG emissions of CaNWtNBaN by 17 and 28% respectively. Results of the study indicate considerable scope for reducing the carbon footprint of subtropical, dryland grains cropping in Australia.

Soil Research, 56(7), p. 724-736

1838-6768

1838-675X

https://hdl.handle.net/1959.11/27126

CSIRO Publishing

Greenhouse gas emission reductions in subtropical cereal-based cropping sequences using legumes, DMPP-coated urea and split timings of urea application

Journal Article

Publication