Guest essay by Eric Worrall
A new study attacks the practice of using fertiliser to produce high wheat yields for bread, claiming that current use of fertiliser is “unsustainable”, due to the energy required to manufacture the fertiliser.
How to reduce the environmental impact of a loaf of bread? (Update)
With an estimated 12 million loaves sold in the UK every day, bread remains a staple of the British diet. In a groundbreaking study researchers from the University of Sheffield have now calculated the environmental impact of a loaf of bread and which part of its production contributes the most greenhouse gas.
Dr Liam Goucher, N8 Agrifood Research Fellow from the University of Sheffield who carried out the study, said: “Consumers are usually unaware of the environmental impacts embodied in the products they purchase – particularly in the case of food, where the main concerns are usually over health or animal welfare.
“There is perhaps awareness of pollution caused by plastic packaging, but many people will be surprised at the wider environmental impacts revealed in this study.
“We found in every loaf there is embodied global warming resulting from the fertiliser applied to farmers’ fields to increase their wheat harvest. This arises from the large amount of energy needed to make the fertilizer and from nitrous oxide gas released when it is degraded in the soil.”
“The findings raise a very important issue – whose responsibility is it to bring about the implementation of these interventions: the fertiliser manufacturer, the farmer, the retailer or the consumer?
“There is a growing recognition for a range of industrial processes of the notion of extended producer responsibility – the producer being responsible for downstream impact, expanded to the idea of shared producer and consumer responsibility. The consumer is key, whether being persuaded to pay more for a greener product or by applying pressure for a change in practice.”
Co-author Professor Duncan Cameron, Co-director of the P3 Centre for Translational Plant and Soil Science explains: “The fertiliser problem is solvable – through improved agronomic practices”.
“These harness the best of organic farming combined with new technologies to better monitor the nutritional status of soils and plants and to recycle waste and with the promise of new wheat varieties able to utilise soil nitrogen more efficiently”.
The abstract of the study;
The environmental impact of fertilizer embodied in a wheat-to-bread supply chain
Liam Goucher, Richard Bruce, Duncan D. Cameron, S. C. Lenny Koh & Peter Horton
Food production and consumption cause approximately one-third of total greenhouse gas emissions, and therefore delivering food security challenges not only the capacity of our agricultural system, but also its environmental sustainability. 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 impacts. 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) tool, 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.
Read more: http://www.nature.com/articles/nplants201712
Sadly the full study is paywalled. But in a world where millions of people are still on the edge of starvation, and where millions more have only just gained access to the benefits of modern fertiliser, talking about restrictions, shared responsibility and presumably financial penalties to make fertiliser less accessible in my opinion is unconscionable.