Analyzing a food system transition by nitrogen flow: Aussois a case study of the progressive decoupling of production and consumption

We reconstructed the one-century evolution of the agri-food system of the municipality of Aussois. We considered the nitrogen and money flows. Two periods are distinguished: from 1925 to 1965, characterized by autonomous agro-pastoral systems, while the second period from 1965 to the present, is defined by specialized and intensive grazing systems with an autonomy of 67%. Nitrogen use efficiency almost no changes between the two periods. Only 10% of nitrogen inputs are fixed in the products of the first period and 11% for the second period. Productivity, or the amount of products produced by surface is multiplied by 2.5 to reach today 7.2 kg N/ha/year. Finally, there is an opening of the nitrogen cycle and an economic transition from a low cash flow closely linked to nitrogen flow, to a significant cash flows independent of nitrogen flow.