Linkages between food system and socioecological nitrogen flows

This project aims to analyze the changing role of food production and consumption as a driver of N flows during the transition from an agrarian to an industrial society, and the exploration of its future role in coming decades. Management of nitrogen flows is central to this transition, as it allowed for surges in biomass production due to land intensification. This has allowed to substantially reducing per-capita land requirements for food production, despite growing calorie and animal product intake in the course of industrialization. At the same time, the links between regional food consumption and food supply changed significantly. Changes in N management for food production as well as changes in diet are strongly influenced by day-to-day decision-making processes of farmers, consumers and other actors. Biophysical and socioeconomic framework conditions are the main drivers and constraints for the option space for each of these decisions that in their sum determine future developments. The project aims to develop a fully integrated socioecological model called NFC (Nitrogen and Food flow Changes) to study historical and possible future changes of nitrogen stocks and flows in the Upper Austrian Enns valley. NFC will be used to analyze trajectories of N flows in the time period of 1830-2030. NFC-model will endogenously represent (a) decisions of relevant actors, (b) spatially explicit changes in land use and land cover and (c) socioeconomic as well as ecological stocks and flows of nitrogen (with adequate spatial as well as temporal resolution). The main goal of NFC is to further our understanding of the interplay of socioeconomic and natural drivers in influencing stocks and flows of N, one of the most important chemical elements due to its multiple roles as plant nutrient, as pollutant (NO x , NH 4 ) and as a potent greenhouse gas (N2 O). The project aims to explore the option space for future developments, which depends on both internal choices and on changes in the framework conditions, thereby supporting local, regional and even supra-regional decision-making. The principal outcome of the project will be a model-based integrated understanding of past states and trajectories and future option space, grounded in historical evidence. Moreover, the project will support Long-Term Socio-Ecological Research (LTSER) by providing a method for integrating concepts and data from social sciences, humanities and natural sciences into a coherent system and thereby facilitate integrated analysis of processes of society-nature interaction.

The use of nitrogen fertilizers in agriculture accelerates plant growth and results in higher yields. At the same time, however, influencing the natural nitrogen cycle has other consequences: Unused fertilizer enters the groundwater and poses a health risk as nitrate, and in the chemical compound nitrous oxide (N2O) plays a central role in climate change. The conditions under which food is produced have changed considerably in recent centuries. The use of nitrogen depends on many factors. Agricultural subsidies and food prices play a role. The social situation on the farm, such as the workload and the life stage of the people working there, also have a significant influence on how land use is managed. Many of these conditions have changed significantly in recent decades, and will continue to change in future. In the ALISEN project, we developed an integrated socio-ecological model to investigate changes in nitrogen flows in the Enns Valley (Austria) in order to represent decisions of relevant actors, spatially explicit changes in land use and socio-economic as well as ecological nitrogen flows. On the one hand, the research question aims at deepening the understanding of the mentioned processes in the past. On the other hand, the focus is on the option space for future developments, which depends on both internal decisions and changes in the framework conditions, and thus supports local, regional and even supra-regional decision-making processes. We have developed a decision model for the period up to 2050. The projected spatially high-resolution land use changes are used as inputs to the soil modelling tool LandscapeDNDC to quantify changes in nitrogen use efficiency. The resulting scenarios show a slight reduction of nitrogen use efficiency for arable land until 2050 because organic farming increases and the remaining cropping systems show an intensification. The nitrogen use efficiency on grassland shows an apparent increase because of the disproportionate decrease in intensive grassland, which has a considerably lower nitrogen use efficiency as compared to extensive grassland. The decision model developed in ALISEN can provide results of land use change at scales appropriate to process-based soil modelling such as LDNDC and has thus provided a methodological innovation in coupling socio-economic decision models with ecosystem models. Furthermore, the method of participatory modelling - aiming to integrate social and scientific knowledge - has its strength in structuring communication about future scenarios and recommendations for action from different actors involved in transdisciplinary research.