With an estimated 12 million loaves sold in the UK every day, bread remains a staple of the British diet.
In a ground-breaking 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.
The group of interdisciplinary researchers from the University’s Grantham Centre for Sustainable Futures, analysed the complete process from growing and harvesting the wheat; milling the grain; producing the flour; baking the bread and the production of the final product, ready to be sold by retailers.
The findings, published in the journal Nature Plants, show ammonium nitrate fertiliser used in wheat cultivation contributes almost half (43 per cent) of the greenhouse gas emissions – dwarfing all other processes in the supply chain.
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.”
How to produce sufficient healthy and affordable food for the world’s growing and more demanding population, whilst protecting the environment is one of the biggest challenges of the 21st century.
Professor Peter Horton FRS, Chief Research Advisor to the Grantham Centre for Sustainable Futures at the University of Sheffield and corresponding author of the paper, said: “With over 100 million tonnes of fertiliser used globally each year to support agricultural production this is a massive problem, but environmental impact is not costed within the system and so there are currently no real incentives to reduce our reliance on fertiliser.
“How to achieve sustainable global food security is not only a technical question but a political economic one, and requires interdisciplinary research of the kind we do here at Sheffield.”
Co-author Professor Duncan Cameron, Co-director of P3 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”.
For more about this story, please visit the website of the Grantham Centre for Sustainable Futures.