The environmental impact of fertilizer embodied in a wheat-to-bread supply chain


Food production and consumption cause approximately one-third of total greenhouse gas emissions13, and therefore delivering food security challenges not only the capacity of our agricultural system, but also its environmental sustainability47. Knowing where and at what level environmental impacts occur within particular food supply chains is necessary if farmers, agri-food industries and consumers are to share responsibility to mitigate these impacts7,8. Here we present an analysis of a complete supply chain for a staple of the global diet, a loaf of bread. We obtained primary data for all the processes involved in the farming, production and transport systems that lead to the manufacture of a particular brand of 800 g loaf. The data were analysed using an advanced life cycle assessment (LCA) tool9, yielding metrics of environmental impact, including greenhouse gas emissions. We show that more than half of the environmental impact of producing the loaf of bread arises directly from wheat cultivation, with the use of ammonium nitrate fertilizer alone accounting for around 40%. These findings reveal the dependency of bread production on the unsustainable use of fertilizer and illustrate the detail needed if the actors in the supply chain are to assume shared responsibility for achieving sustainable food production.

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Figure 1: The wheat-to-bread supply chain.
Figure 2: Process group environmental impact.
Figure 3: Environmental impact of ammonium nitrate fertilizer in comparison to other process groups.


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We thank the Grantham Foundation for the Protection of the Environment for their generous support. L.G. was supported in part by Impact, Innovation and Knowledge Exchange (IIKE) funds from the University of Sheffield and pump priming funding from the P3 Centre. We also gratefully acknowledge the support of our commercial partners.

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P.H. and S.C.L.K. conceived the study, R.B. negotiated with the commercial partners and L.G. carried out the collection and analysis of the data. All authors were involved in the interpretation of the findings and the writing of the paper.

Corresponding author

Correspondence to Peter Horton.

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The authors declare no competing financial interests.

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Supplementary Information

Supplementary Figures 1–6, Supplementary Table 1. (PDF 539 kb)

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Goucher, L., Bruce, R., Cameron, D. et al. The environmental impact of fertilizer embodied in a wheat-to-bread supply chain. Nature Plants 3, 17012 (2017).

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