Laurence cites the work that I was involved in at Silsoe Research Institute (SRI) and the early days of Cranfield University. Looking at the environmental burdens of producing 10 food commodities in England and Wales. The paper cited looks at the main arable crops wheat, oilseed-rape, and potatoes . Read more about his project here Environmental Burdens of Agricultural and Horticultural Commodity Production – LCA (IS0205)