Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/20172
Title: Annual crop legumes may not mitigate greenhouse gas emissions because of the high carbon cost of nitrogen fixation
Contributor(s): Herridge, David  (author)orcid ; Brock, Philippa M (author)
Publication Date: 2016
Handle Link: https://hdl.handle.net/1959.11/20172
Abstract: A large uncertainty in constructing grain cropping Life Cycle Assessments (LCAs) is the effect of a particular crop, or sequence of crops, on soil C stocks. We propose that the C cost of legume N₂ fixation, estimated to be ca. 20 kg CO₂/kg N fixed, will be expressed as reduced residue C returned to the soil and a possible net loss of soil C. Published pre-farm + on-farm greenhouse gas (GHG) emissions associated with N-fertilised wheat (60N) and canola (100N) and N₂-fixing field pea, grown in Australia's southern grains region, were combined with modelled effects of the same crops on soil C stocks. When effects of the crops on soil C were assumed to be neutral, canola had the highest emissions at 840 kg CO₂-e/ha with field pea the lowest (530 kg CO₂-e/ha). When estimated changes in soil C were included in the LCAs, canola's GHG emission were totally offset (-100 kg CO₂-e/ha), compared with a more than doubling of emissions for field pea to 1270 kg CO₂-e/ha. This is somewhat counter-intuitive to current thinking that the substitution of fertiliser N with legume fixed N is an effective strategy for GHG emissions mitigation and highlights the need for simple, accurate methodologies for determining net changes in soil C for individual crops.
Publication Type: Conference Publication
Conference Name: INI 2016: 7th International Nitrogen Initiative Conference, "Solutions to improve nitrogen use efficiency for the world", Melbourne, Australia, 4th - 8th December, 2016
Conference Details: INI 2016: 7th International Nitrogen Initiative Conference, "Solutions to improve nitrogen use efficiency for the world", Melbourne, Australia, 4th - 8th December, 2016
Source of Publication: Proceedings of the 2016 International Nitrogen Initiative Conference, "Solutions to improve nitrogen use efficiency for the world", p. 1-4
Publisher: International Nitrogen Initiative
Place of Publication: online
Field of Research (FOR): 070302 Agronomy
050204 Environmental Impact Assessment
Socio-Economic Outcome Codes: 960504 Ecosystem Assessment and Management of Farmland, Arable Cropland and Permanent Cropland Environments
Peer Reviewed: Yes
HERDC Category Description: E1 Refereed Scholarly Conference Publication
Other Links: http://www.ini2016.com/pdf-papers/INI2016_Herridge_David.pdf
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Appears in Collections:Conference Publication
School of Environmental and Rural Science

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