Agri-food-energy system metabolism: a historical study for northern France, from nineteenth to twenty-first centuries

Abstract

We reconstruct the metabolism of cereal grain production and processing systems in the Seine river basin at four time points between 1860 and 2010 in terms of nitrogen and energy flows, on the basis of statistical data and modeling components. We integrate agricultural, nutrient and energy issues into a joint agri-food-energy system approach. Grain production and processing grew apart from a state of high local integration on the basis of local renewable energy and nitrogen sources to a state of national-scale energy and grain market integration. The grain production volume increased 6-fold under the effect of agricultural industrialization, while the local grain processing capacity dropped along with the decrease in local flour demand. Nitrogen use efficiency (NUE) increased from about 50% in the nineteenth century to about 66% today, and the fossil energy inputs to the system increased from 0.05 to 0.15 GJ/GJ of flour output. Nitrogen loss is today lower than in the early-twentieth century, but its embodied fossil energy content is five times higher, highlighting potential energy benefits from further NUE increase. The energy transition to fossil fuels marked the disruption of an agro-industrial regime founded on renewable energy self-provision and biological nitrogen fixation and helped mastering the system working conditions by reducing its intermittency.